ISO 18610:2016

Fine ceramics (advanced ceramics, advanced technical ceramics) — Mechanical properties of ceramic composites at ambient temperature in air atmospheric pressure — Determination of elastic properties by ultrasonic technique

ISO 18610:2016 specifies an ultrasonic method to determine the components of the elasticity tensor of ceramic matrix composite materials at room temperature. Young's moduli shear moduli and Poisson coefficients, can be determined from the components of the elasticity tensor. It applies to ceramic matrix composites with a continuous fibre reinforcement: unidirectional (1D), bidirectional (2D), and tridirectional (×D, with 2 This method is applicable only when the ultrasonic wavelength used is larger than the thickness of the representative elementary volume, thus imposing an upper limit to the frequency range of the transducers used.

Céramiques techniques (céramiques avancées, céramiques techniques avancées) — Propriétés mécaniques des céramiques composites à température ambiante sous air à pression atmosphérique — Détermination des propriétés élastiques par méthode ultrasonore

L'ISO 18610:2016 spécifie une méthode ultrasonore pour déterminer les composantes du tenseur d'élasticité des composites à matrice céramique à température ambiante. Les modules de Young, les modules de cisaillement et les coefficients de Poisson peuvent être déterminés à partir des composantes du tenseur d'élasticité. L'ISO 18610:2016 s'applique aux composites à matrice céramique à renfort fibreux continu unidirectionnels (1D), bidirectionnels (2D) et tridirectionnels (× D, avec 2 Cette méthode est uniquement applicable lorsque la longueur d'onde ultrasonore utilisée est supérieure à l'épaisseur du volume élémentaire représentatif, ce qui impose une limite supérieure à la gamme de fréquences des traducteurs utilisés.

General Information

• Status: Published
• Publication Date: 18-Sep-2016
• ICS: 81.060.30 - Advanced ceramics
• Technical Committee: ISO/TC 206 - Fine ceramics
• Drafting Committee: ISO/TC 206/WG 4 - Composites
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 14-Mar-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 18610
First edition
2016-09-15
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Mechanical properties of ceramic
composites at ambient temperature
in air atmospheric pressure —
Determination of elastic properties by
ultrasonic technique
Céramiques techniques (céramiques avancées, céramiques techniques
avancées) — Propriétés mécaniques des céramiques composites
à température ambiante sous air à pression atmosphérique —
Détermination des propriétés élastiques par méthode ultrasonore
Reference number
ISO 18610:2016(E)
ISO 2016
---------------------- Page: 1 ----------------------
ISO 18610:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2016 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 18610:2016(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 5

5 Significance and use .......................................................................................................................................................................................... 6

6 Test equipment....................................................................................................................................................................................................... 7

6.1 Immersion tank with temperature measurement device .................................................................................. 7

6.2 Holder of the probes and test object .................................................................................................................................... 7

6.3 Probes ............................................................................................................................................................................................................. 7

6.4 Pulse generator ....................................................................................................................................................................................... 7

6.5 Signal display and recording system .................................................................................................................................... 7

7 Test object .................................................................................................................................................................................................................... 7

8 Test object preparation ................................................................................................................................................................................. 8

9 Test procedure ........................................................................................................................................................................................................ 8

9.1 Choice of frequency ............................................................................................................................................................................. 8

9.2 Establishment of the test temperature .............................................................................................................................. 9

9.3 Reference test without test object .......................................................................................................................................... 9

9.4 Measurement with the test object .......................................................................................................................................... 9

9.4.1 Determination of the bulk density and thickness ............................................................................... 9

9.4.2 Mounting of the test object ..................................................................................................................................... 9

9.4.3 Acquisition of different angles of incidence ............................................................................................. 9

10 Calculation ...............................................................................................................................................................................................................10

10.1 Delay .............................................................................................................................................................................................................10

10.2 Calculation of the propagation velocities ......................................................................................................................10

10.3 Calculation of the refracted angle, θ ...............................................................................................................................10

10.4 Identification of the elastic constants, C .....................................................................................................................10

10.4.1 Basic considerations ..................................................................................................................................................10

10.4.2 Calculation of C ........................................................................................................................................................12

10.4.3 Calculation of C , C and C ........................................................................................................................12

22 23 44

10.4.4 Calculation of C , C and C ........................................................................................................................12

11 13 55

10.4.5 Calculation of C and C ...................................................................................................................................12

12 66

10.5 Polar plots of the velocity curves .........................................................................................................................................13

10.6 Calculation of the quadratic deviation and the confidence interval ......................................................14

10.7 Calculation of the engineering constants ......................................................................................................................14

11 Test validity .............................................................................................................................................................................................................15

11.1 Measurements ......................................................................................................................................................................................15

11.2 Criterion of validity for the reliability of the C components ......................................................................15

12 Test report ................................................................................................................................................................................................................15

Annex A (informative) Example of a presentation of the results for a material with

orthotropic symmetry .................................................................................................................................................................................17

Bibliography .............................................................................................................................................................................................................................19

© ISO 2016 – All rights reserved iii
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ISO 18610:2016(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,

as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the

Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.

The committee responsible for this document is ISO/TC 206, Fine ceramics.
iv © ISO 2016 – All rights reserved
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INTERNATIONAL STANDARD ISO 18610:2016(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Mechanical properties of ceramic composites
at ambient temperature in air atmospheric pressure
— Determination of elastic properties by ultrasonic
technique
1 Scope

This document specifies an ultrasonic method to determine the components of the elasticity tensor of

ceramic matrix composite materials at room temperature. Young’s moduli shear moduli and Poisson

coefficients, can be determined from the components of the elasticity tensor.

This document applies to ceramic matrix composites with a continuous fibre reinforcement:

unidirectional (1D), bidirectional (2D), and tridirectional (×D, with 2 < × ≤ 3) which have at least

orthotropic symmetry, and whose material symmetry axes are known.

This method is applicable only when the ultrasonic wavelength used is larger than the thickness of

the representative elementary volume, thus imposing an upper limit to the frequency range of the

transducers used.

NOTE Properties obtained by this method might not be comparable with moduli obtained by ISO 15733,

ISO 20504 and EN 12289.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 3611, Geometrical product specifications (GPS) — Dimensional measuring equipment: Micrometers for

external measurements — Design and metrological characteristics

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

EN 1389, Advanced technical ceramics — Ceramic composites — Physical properties — Determination of

density and apparent porosity
3 Terms and definitions

For the purposes of this document, the terms and definitions given in CEN/TR 13233 and the

following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
© ISO 2016 – All rights reserved 1
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ISO 18610:2016(E)
3.1
stress-strain relations for orthotropic material

elastic anisotropic behaviour of a solid homogeneous body described by the elasticity tensor of fourth

order C , represented in the contracted notation by a symmetrical square matrix (6 × 6)

ijkl

Note 1 to entry: If the material has at least orthotropic symmetry, its elastic behaviour is fully characterized

by nine independent stiffness components C , of the stiffness matrix (C ), which relates stresses to strains, or

ij ij

equivalently by nine independent compliance components S of the compliance matrix (S ), which relates strains

ij ij

to stresses. The stiffness and compliance matrices are the inverse of each other.

If the reference coordinate system is chosen along the axes of symmetry, the stiffness matrix C and the

compliance matrix S can be written as follows:
     
σ C C C 00 0 ε
1 11 12 13 1
     
σ CC C 000 εε
     
2 12 22 23 2
     
σ C CC 000 ε
3 113 23 33 3
     
σ 000 C 00 ε
     
4 44 4
     
σ 000 00C ε
5 55 5
     
σ  000 00 C  ε 
6 66 6
     
     
ε SS S 00 0 σ
1 11 12 13 1
     
ε SS S 000 σσ
  
2 12 22 23  2
     
ε S SS 000 σ
3 113 23 33 3
     
ε 000 S 00 σ
     
4 44 4
     
ε 000 00S σ
5 55 5
     
ε  000 00 S  σ 
6 66 6
     

Note 2 to entry: For symmetries of higher level than the orthotropic symmetry, the C and S matrices have the

ij ij
same form as here above. Only the number of independent components reduces.
3.2
engineering constants

compliance matrix components of an orthotropic material which are in terms of engineering constants:

 
−ν −ν
121 31
00 0
 
11 33
 
−ν −ν
12 1 32
 00 0 
11 33
 
−νν
 
13 23 1
00 0
 E 
 
E E
S =
ij 11 33
 
 
00 0 00
 
 
00 00 0
 
 
00 00 0
 
 12
where
E , E and E are the elastic moduli in directions 1, 2 and 3, respectively;
11 22 33
G , G and G are the shear moduli in the corresponding planes;
12 13 23
ν , ν , ν are the respective Poisson coefficients.
12 13 23
2 © ISO 2016 – All rights reserved
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ISO 18610:2016(E)
3.3
angle of incidence

angle between the direction 3 normal to the test specimen front face and the direction n of the

incident wave
Note 1 to entry: See Figures 1 and 2.
3.4
refracted angle

angle between the direction 3 normal to the test specimen front face and the direction n of propagation

of the wave inside the test specimen
Note 1 to entry: See Figures 1 and 2.
3.5
azimuthal angle

angle between the plane of incidence (3, n ) and plane (2, 3) where n corresponds to the vector oriented

i i

along the incident plane wave and direction 2 corresponds to one of the axes of symmetry of the

material
Note 1 to entry: See Figure 1.
Figure 1 — Definition of angles
© ISO 2016 – All rights reserved 3
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ISO 18610:2016(E)
Figure 2 — Propagation in the plane of incidence
3.6
first critical angle

angle of incidence θ that provides an angle of refraction of 90 degrees of the quasi longitudinal wave angle

3.7
unit vector

vector of length 1 oriented along the propagation direction of the incident plane wave inside the

specimen, with its components n (k = 1, 2, 3):
n =sinsθψin
1 r
n =sincθψos
2 r
n =cosθ
3 r
Note 1 to entry: See Figures 1 and 2.
3.8
propagation velocity
V(n)

phase velocity of a plane wave inside the specimen in dependence on unit vector n (i.e. in dependence

on ψ and θ )
Note 1 to entry: V is the propagation velocity in the coupling fluid.
3.9
delay
δt(n)

difference between the time-of-flight of the wave when the test specimen is in place and the time-of-

flight of the wave in the coupling fluid with the test specimen removed under the same configuration of

the probes in dependence on unit vector n
3.10
bulk density

ratio of the mass of the material without porosity to its total volume including porosity

4 © ISO 2016 – All rights reserved
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ISO 18610:2016(E)
4 Principle

The determination of the elastic properties consists of calculating the coefficients of the propagation

equation of an elastic plane wave, from a set of properly chosen velocity measurements along known

directions.

A thin specimen with plane parallel faces is immersed in an acoustically coupling fluid (e.g. water),

see Figure 3. The specimen is placed between a transmitter (T) and a receiver (R), which are rigidly

connected to each other and have two rotational degrees of freedom. Using appropriate signal

processing, the propagation velocities of each wave in the specimen are calculated.

θ i
Key
1 rotation drive
2 test object
3 pulse generator
4 digital oscilloscope
5 micro-computer
Figure 3 — Ultrasonic test assembly

Depending on the angle of incidence, the wave created by the pulse sent by the transmitter T is refracted

within the material in one (a quasi longitudinal wave QL, or a quasi transverse wave QT), two (QL+ QT or

two quasi transverse waves QT , QT ) or three bulk waves (QL+ QT +QT ) that propagate in the solid at

1 2 1 2
different velocities and in different directions.

The receiver R collects one, two or three pulses, corresponding to each of these waves.

The difference between the time-of-flight of each of the waves and the time-of-flight of the transmitted

pulse in the coupling fluid without the test object is measured. The evaluation procedure is based on

the measurement of the time-of-flight of the quasi-longitudinal and one or both quasi-transverse waves,

and is only valid when the QL and the QT waves are appropriately separated (see Figure 4).

© ISO 2016 – All rights reserved 5
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ISO 18610:2016(E)
05 10 15 20 25
Key Key
Y amplitude Y amplitude
X angle of incidence X time
NOTE Both QL and QT waves are present and can
be distinguished in the positive domain but are
slightly overlapping in the negative domain.

a) Amplitude of the QL and QT waves as a b) Temporal waveform of the QL and QT waves

function of the angle of incidence with at an angle of incidence, θ , close to the critical

overlapping in the region of θ angle, θ
c c

Figure 4 — Example of partial overlapping of QL and QT waves at an angle of incidence θ

From the propagation velocities, the components of the elasticity tensor are obtained through a least

square regression analysis which minimizes the residuals of the wave propagation equations.

Young’s moduli, shear moduli and Poisson coefficients are determined from these components.

5 Significance and use

Only two constants (Lamés coefficients, Young’s modulus and Poisson coefficient, Young’s and shear

moduli, longitudinal and transverse wave velocities) are sufficient in order to fully describe the

elastic behaviour of an isotropic solid body. When anisotropy, which is a specific feature of composite

materials, shall be taken into account, the use of an elasticity tensor with a larger number of independent

coefficients is needed. While conventional mechanical methods allow only a partial identification of

the elasticity of anisotropic bodies, ultrasonic techniques allow a more exhaustive evaluation of the

elastic properties of these materials, particularly transverse elastic moduli and shear moduli for thin

specimens.

Successful application of the method depends critically on an appropriate selection of the central

frequency of the transducers. Frequency shall be sufficiently low for the measurement to be

representative of the elementary volume response, but at the same time high enough to achieve a

separation between the QL and the QT waves.

The determination of elastic properties by the ultrasonic technique described here is based on a non-

destructive dynamic measurement of wave propagation velocities. The determination of the values of

Young’s moduli, shear moduli and Poisson ratios need a single specimen.
6 © ISO 2016 – All rights reserved
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ISO 18610:2016(E)
6 Test equipment
6.1 Immersion tank with temperature measurement device

The temperature of the coupling fluid in the immersion tank should stay constant within ±0,5 °C for the

full duration of the test.

The temperature measurement device shall be capable of measuring the temperature to within 0,5 °C.

This requirement is imposed because the wave propagation velocity in the coupling fluid is temperature

sensitive.
6.2 Holder of the probes and test object

The holder of the ultrasonic probes or the holder of the test object shall allow a rotation to cover the

range of angles of incidence θ between 0° and 90°. Additionally, it shall allow for discrete settings of the

azimuthal angle ± of 0°, 45° and 90°. The accuracy in the measurement of the angles θ and ψ shall be

better than 0,1° and 1°, respectively.

The probes shall be mounted in such a way that their relative position remains fixed during the test.

6.3 Probes

Piezoelectric broad-band probes adapted to the coupling fluid and able to generate longitudinal

ultrasonic waves shall be used. Two probes with similar specifications (e.g. central frequency,

bandwidth) shall be used as transmitter and receiver.
6.4 Pulse generator

The pulse generator shall be selected in accordance with the characteristics of the probes.

It shall be able to generate short-duration (<1 µs) sinusoidal pulses of voltage sufficient to provide a

mechanical pulse by the transducer. The frequency of the exciting pulse shall be chosen, such as

described in 9.1.

The interval between consecutive pulses shall be long compared with the travel time being recorded,

typically greater than 1 ms, so that all signals from the preceding pulse have dissipated before initiating

the next.
6.5 Signal display and recording system

Use any system, for instance, e.g. digital oscilloscope, with a minimum sampling frequency of 100 MHz

that allows the recording of transmitted and received signals. The signal recording system is designed

in order to allow one to see on the display the generated and the detected pulses on the same time-base

and to determine the time-gap separating these two events.
7 Test object

The choice of the geometry of the test object depends on the nature of the material and the

reinforcement structure. The thickness shall be large enough to allow separation of the echoes of the

quasi longitudinal QL and quasi transverse QT waves and shall be representative of the material. The

largest possible thickness is recommended, at least five times the size of the representative volume

element (RVE) in the direction of propagation of the wave. The other dimensions of the test object shall

be at least twice the diameter of the transducer. A test object with parallel faces is mandatory. The two

faces shall be parallel of better than 0,1 mm.
© ISO 2016 – All rights reserved 7
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ISO 18610:2016(E)
8 Test object preparation

The material symmetry axes shall be identified. If machining is required, it shall be performed in such a

way that the material symmetry axes remain known at all times.

Machining procedures that do not cause damage to the test objects shall be clearly defined and recorded.

These procedures shall be followed during machining of the test objects.

NOTE Usually, test objects from plates are cut with their longitudinal axis coinciding with one of the

principal directions of the reinforcement.

One test object is sufficient to perform the test. Multiple measurements can be done on a single test object.

Care shall be taken to avoid chemical interaction between the coupling fluid and the test object.

9 Test procedure
9.1 Choice of frequency

The selection of the appropriate frequency is critical for the application of the method. The frequency

shall be sufficiently low to ensure that the measurement is representative.

NOTE 1 An initial selection of f < 02, , where d is the characteristic length of the RVE in the direction of

normal incidence, is proposed (θ = 0).

Where d is the characteristic length of the RVE in the direction of normal incidence (θ = 0) and V the

propagation velocity inside the specimen and in that direction, is proposed.

NOTE 2 Because of the inverse relationship between wavelength λ and frequency f ( f = ), this corresponds

to a wavelength λ of at least 5d.
For the selected frequency, the following additional criteria should be met:

a) measurable amplitude of the QL wave under normal incidence θ = 0. If the amplitude is too small,

the frequency shall be decreased;

b) time separation of the waves QL and QT when varying the angle of incidence θ [see Figure 4 b)].

This is promoted by increasing the frequency.
A minimum frequency of is recommended.

Because the frequency requirements for meeting the three mentioned criteria may be conflicting, there

are cases where the method is not applicable. In these cases, the only remaining solution is to increase

the thickness of the test object beyond the minimum thickness stipulated in Clause 7.

NOTE 3 For example, for a 2D SiC/SiC with a RVE of 0,5 mm (requiring a minimum thickness of the test object

of 2,5 mm in accordance with Clause 7), the test frequency, in order for the measurement to be representative, is

lower than 2,25 MHz (corresponding to wave velocities of around 5 000 m/s). On the other hand, for obtaining

mode separation, the frequency is higher than = 3MHz . The method can therefore not be applied for the

given thickness of 2,5 mm. An increase in thickness to 3,3 mm allows mode separation at a frequency of 2,25 MHz.

8 © ISO 2016 – All rights reserved
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ISO 18610:2016(E)
9.2 Establishment of the test temperature

Measure the temperature of the coupling fluid at a location between the transducers in the vicinity of

the future position of the test specimen. Perform the reference measurement in accordance with 9.3.

Perform the test in accordance with 9.4.
9.3 Reference test without test object

Record the signals from the transmitter and from the receiver versus time without a test object

mounted.
9.4 Measurement with the test object
9.4.1 Determination of the bulk density and thickness
9.4.1.1 Determination of the bulk density
The bulk density shall be determined in accordance with EN 1389.
9.4.1.2 Measurement of the thickness

The thickness shall be measured in three positions on the test area with a calliper with an inaccuracy

less than 0,02 mm in accordance with ISO 3611.
9.4.2 Mounting of the test object
Mount the test object in the holder.
Measure the temperature in the vicinity of the test object.

Make sure that the measured temperature falls within ±0,5 °C from that of the reference measurement.

The test object shall be oriented perpendicularly to the incoming beam. The inaccuracy of the

perpendicularity between the beam and the specimen shall be below 0,1 mm.

The test specimen shall be mounted in such a way that one of the symmetry axes coincides with ψ = 0°

to within 1°.
9.4.3 Acquisition of different angles of incidence

Set acquisition plane by selecting azimuthal angle ψ = 0°, 45° and 90°. For each acquisition, plane

measurements shall be made of the QL and QT signals at given values of the angle of incidence θ . The

angle of incidence θ varies from 0° up to a maximum defined by a decrease of the amplitude of the QT

wave to approximately one third of its maximum. The number of incidence angles shall be selected to

optimise coverage over the range in which both the QL and QT waves appear.

Over the total range of θ usually a minimum of 20 measurements shall be performed.

The maximum angle θ is also configuration limited.

Only signals recorded at values of θ and ψ meeting the following conditions can be used for subsequent

calculation and evaluation of C :
a) the bulk waves are clearly identified (i.e.
...

DRAFT INTERNATIONAL STANDARD
ISO/DIS 18610
ISO/TC 206 Secretariat: JISC
Voting begins on: Voting terminates on:
2015-07-08 2015-10-08
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Mechanical properties of ceramic composites
at room temperature — Determination of elastic
properties by an ultrasonic technique

Céramiques techniques — Propriétés mécaniques des céramiques composites à température ambiante —

Détermination des propriétés élastiques par une méthode ultrasonore
ICS: 81.060.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 18610:2015(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2015
---------------------- Page: 1 ----------------------
ISO/DIS 18610:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2015 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DIS 18610:2015(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms definitions and symbols ............................................................................................................................................................. 1

4 Principle ........................................................................................................................................................................................................................ 4

5 Significance and use .......................................................................................................................................................................................... 7

6 Apparatus ..................................................................................................................................................................................................................... 7

6.1 Ultrasonic tank with temperature measurement device .................................................................................... 7

6.2 Ultrasonic transducers versus specimen holder ....................................................................................................... 7

6.3 Transducers ............................................................................................................................................................................................... 7

6.4 Pulse generator ....................................................................................................................................................................................... 7

6.5 Signal recording system .................................................................................................................................................................. 8

7 Test specimens........................................................................................................................................................................................................ 8

8 Test specimen preparation ........................................................................................................................................................................ 8

9 Test procedure ........................................................................................................................................................................................................ 8

9.1 Choice of frequency ............................................................................................................................................................................. 8

9.2 Establishment of the test temperature .............................................................................................................................. 9

9.3 Reference test without test specimen ................................................................................................................................. 9

9.4 Measurement with the specimen ............................................................................................................................................ 9

9.4.1 Measurement of the bulk density and of the thickness .................................................................. 9

9.4.2 Mounting of the specimen ....................................................................................................................................... 9

9.4.3 Acquisition of different angles of incidence ............................................................................................. 9

10 Calculation ...............................................................................................................................................................................................................10

10.1 Delay .............................................................................................................................................................................................................10

10.2 Calculation of the propagation velocities ......................................................................................................................10

10.3 Calculation of the refracted angle θ ..................................................................................................................................

r 10

10.4 Identification of the elastic constants, C .......................................................................................................................

ij 11

10.4.1 Basic considerations ..................................................................................................................................................11

10.4.2 Calculation of C ...........................................................................................................................................................

33 12

10.4.3 Calculation of C , C and C ...........................................................................................................................

22 23 44 12

10.4.4 Calculation of C , C and C ...........................................................................................................................

11 13 55 12

10.4.5 Calculation of C and C ......................................................................................................................................

12 66 12

10.5 Polar plots of the velocity curves .........................................................................................................................................13

10.6 Calculation of the quadratic deviation and the confidence interval ......................................................14

10.7 Calculation of the engineering constants ......................................................................................................................14

11 Test validity .............................................................................................................................................................................................................15

11.1 Measurements ......................................................................................................................................................................................15

11.2 Criterion of validity for the reliability of the C components ......................................................................15

12 Test report ................................................................................................................................................................................................................15

Annex A (informative) Example of a presentation of the results for a material with

orthothropic symmetry ..............................................................................................................................................................................17

Bibliography .............................................................................................................................................................................................................................19

© ISO 2015 – All rights reserved iii
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ISO/DIS 18610:2015(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any

patent rights identified during the development of the document will be in the Introduction and/or on

the ISO list of patent declarations received. www.iso.org/patents

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers

to Trade (TBT), see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 206, Fine ceramics (advanced ceramics, advanced

technical ceramics).
iv © ISO 2015 – All rights reserved
---------------------- Page: 4 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/DIS 18610:2015(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Mechanical properties of ceramic composites
at room temperature — Determination of elastic
properties by an ultrasonic technique
1 Scope

This International Standard specifies an ultrasonic method to determine the components of the elasticity

tensor of ceramic matrix composite materials at room temperature. Young’s moduli shear moduli and

Poisson coefficients, can be determined from the components of the elasticity tensor.

This International Standard applies to ceramic matrix composites with a continuous fibre reinforcement:

unidirectional (1D), bidirectional (2D), and tridirectional ( × D, with 2 < × ≤ 3) which have at least

orthotropic symmetry, and whose material symmetry axes are known.

This method is applicable only when the ultrasonic wavelength used is larger than the thickness of

the representative elementary volume, thus imposing an upper limit to the frequency range of the

transducers used.

NOTE Properties obtained by this method might not be comparable with moduli obtained by EN 658–1,

EN 658–2 and EN 12289. (Check for ISO EQUIVALENT)
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.

EN 1389, Advanced technical ceramics — Ceramic composites — Physical properties — Determination of

density and apparent porosity

ISO/AWI 19634, Fine ceramics (advanced ceramics, advanced technical ceramics) — Notations and symbols

of ceramic composites

ISO/IEC 17025:2005, General requirements for the competence of testing and calibration laboratories

ISO 3611, Geometrical product specifications (GPS) — Dimensional measuring equipment: Micrometers for

external measurements — Design and metrological characteristics

EN 12668-1, Non-destructive testing — Characterization and verification of ultrasonic examination

equipment — Part 1: Instruments

EN 12668-2, Non-destructive testing — Characterization and verification of ultrasonic examination

equipment — Part 2: Probes

EN 12668-3, Non-destructive testing — Characterization and verification of ultrasonic examination

equipment — Part 3: Combined equipment
3 Terms definitions and symbols

For the purposes of this document, the terms and definitions given in CEN/TR 13233:2007 and the

following apply.
© ISO 2015 – All rights reserved 1
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ISO/DIS 18610:2015(E)
3.1
stress-strain relations for orthotropic material

elastic anisotropic behaviour of a solid homogeneous body described by the elasticity tensor of fourth

order C , represented in the contracted notation by a symmetrical square matrix (6 × 6)

ijkl

Note 1 to entry: If the material has at least orthotropic symmetry, its elastic behaviour is fully characterized

by nine independent stiffness components C , of the stiffness matrix (C ), which relates stresses to strains, or

ij ij

equivalently by nine independent compliance components S of the compliance matrix (S ), which relates strains

ij ij

to stresses. The stiffness and compliance matrices are the inverse of each other.

If the reference coordinate system is chosen along the axes of symmetry, the stiffness matrix C and the

compliance matrix S can be written as follows:
     
σ C C C 00 0 ε
 1  11 12 13   1
     
σ CC C 00 0 ε
 2  12 22 223   2
     
σ CC C 00 0 ε
     
3 13 23 33 3
     
σ 000 C 00 ε
     
4 44 4
     
σ  0000 C 0  ε 
5 55 5
     
σ  00000 C  ε 
6 66 6
     
     
ε SS S 00 0 σ
1 11 12 13 1
     
     
ε SS S 00 0 σ
     
2 12 22 223 2
     
ε SS S 00 0 σ
     
3 13 23 33 3
     
ε 000 S 00 σ
     
4 44 4
     
ε 000 00S σ
     
5 55 5
     
ε  000 00 S  σ 
6 66 6
     

Note 2 to entry: For symmetries of higher level than the orthotropic symmetry, the C and S matrices have the

ij ij
same form as here above. Only the number of independent components reduces.
3.2
engineering constants

compliance matrix components of an orthotropic material which are in terms of engineering constants:

 
−ν −ν
 1 21 31 
00 0
 
EE E
11 22 33
 
−ν −ν
 
12 1 32
00 0
 
EE E
 
11 22 33
 
−ν −ν
13 23 1
 
00 0
 
 
S = E EE
 
111 22 33
   
 000 00 
 G 
 
 000 0 0 
 
 
000 00
 
 
 
where
E , E and E are the elastic moduli in directions 1, 2 and 3 respectively;
11 22 33
G , G and G are the shear moduli in the corresponding planes;
12 13 23
ν , ν , ν are the respective Poisson coefficients
12 13 23
2 © ISO 2015 – All rights reserved
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ISO/DIS 18610:2015(E)
3.3
angle of incidence

angle between the direction 3 normal to the test specimen front face and the direction n of the incident

wave (see Figure 1 and Figure 2)
3.4
refracted angle

angle between the direction 3 normal to the test specimen front face and the direction n of propagation

of the wave inside the test specimen (see Figure 1 and Figure 2)
3.5
azimuthal angle

angle between the plane of incidence (3, n ) and plane (2, 3) where n corresponds to the vector oriented

i i

along the incident plane wave and direction 2 corresponds to one of the axes of symmetry of the material

(see Figure 1)
Figure 1 — Definition of the angles
n 1
Figure 2 — Propagation in the plane of incidence
© ISO 2015 – All rights reserved 3
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ISO/DIS 18610:2015(E)
3.6
first critical angle

angle of incidence θ that provides an angle of refraction of 90-degrees of the quasi longitudinal wave angle

3.7
unit vector

unit vector oriented along the propagation direction of the incident plane wave inside the specimen,

with its components n (k = 1, 2, 3) (see Figure 1 and Figure 2):n = sinθ sinψn = sinθ cosψn = cosθ

k 1 r 2 r 3 r
3.8
propagation velocity
V(n)

phase velocity of a plane wave inside the specimen in dependence on unit vector n (i.e. in dependence

on ψ and θ )
Note 1 to entry: Vo is the propagation velocity in the coupling fluid.
3.9
delay
δt(n)

difference between the flight time of the wave when the test specimen is in place and the flight time

of the wave in the coupling fluid with the test specimen removed under the same configuration of the

transducers in dependence on unit vector n
3.10
bulk density
bulk density of the specimen without porosity
4 Principle

The determination of the elastic properties consists of calculating the coefficients of the propagation equation

of an elastic plane wave, from a set of properly chosen velocity measurements along known directions.

A thin specimen with plane parallel faces is immersed in an acoustically coupling fluid (e.g. water): see

Figure 3. The specimen is placed between an emitter (E) and a receiver (R), which are rigidly connected

to each other and have two rotational degrees of freedom. Using appropriate signal processing, the

propagation velocities of each wave in the specimen are calculated.
4 © ISO 2015 – All rights reserved
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ISO/DIS 18610:2015(E)
θ i
34 5
Key
1 rotation drive
2 test specimen
3 pulse generator
4 digital oscilloscope
5 micro-computer
Figure 3 — Ultrasonic test assembly

Depending on the angle of incidence, the wave created by the pulse sent by the emitter E is refracted

within the material in one (a quasi longitudinal wave QL, or a quasi transverse wave QT), two (QL+ QT or

two quasi transverse waves QT , QT ) or three bulk waves (QL+ QT +QT ) that propagate in the solid at

1 2 1 2
different velocities and in different directions.

The receiver R collects one, two or three pulses, corresponding to each of these waves.

The difference between the propagation time of each of the waves and the propagation time of the emitted

pulse in the coupling fluid without the specimen is measured. The evaluation procedure is based on the

measurement of the time of flight of the quasi-longitudinal and one or both quasi-transverse waves, and

is only valid when the QL and the QT waves are appropriately separated (see Figure 4).

© ISO 2015 – All rights reserved 5
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ISO/DIS 18610:2015(E)
05 10 15 20 25
θ c
Key
1 amplitude
2 incidence angle

a) Amplitude of the QL and QT waves as a function of the incidence angle with overlapping

in the region of θ
Key
1 amplitude
2 time

b) Temporal waveform of the QL and QT waves at an incidence angle θ close to the critical

angle θ . Both QL and QT waves are present and can be distinguished in the positive domain but

are slightly overlapping in the negative domain

Figure 4 — Example of partial Overlapping of QL and QT waves at an incidence angle θ

From the propagation velocities the components of the elasticity tensor are obtained through a least

square regression analysis which minimises the residuals of the wave propagation equations.

Young’s moduli, shear moduli and Poisson coefficients are determined from these components.

6 © ISO 2015 – All rights reserved
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ISO/DIS 18610:2015(E)
5 Significance and use

Only two constants (Lamés coefficients, Young’s modulus and Poisson coefficient, Young’s and shear

moduli, longitudinal and transverse wave velocities) are sufficient in order to fully describe the elastic

behaviour of an isotropic body. When anisotropy, which is a specific feature of composite materials, shall

be taken into account, the use of an elasticity tensor with a larger number of independent coefficients is

needed. While conventional mechanical methods allow only a partial identification of the elasticity of

anisotropic bodies, ultrasonic techniques allow a more exhaustive evaluation of the elastic properties of

these materials particularly transverse elastic moduli and shear moduli for thin specimens.

Successful application of the method depends critically on an appropriate selection of the central

frequency of the transducers. Frequency shall be sufficiently low for the measurement to be representative

of the elementary volume response, but at the same time high enough to achieve a separation between

the QL and the QT waves.

The determination of elastic properties by the ultrasonic method described here is based on a non-

destructive dynamic measurement of wave propagation velocities. The determination of the values of

Young’s moduli, shear moduli and Poisson ratios need a single specimen.
6 Apparatus
6.1 Ultrasonic tank with temperature measurement device

The temperature of the coupling fluid in the ultrasonic tank should stay constant within ± 0,5 °C for the

full duration of the test.

The temperature measurement device shall be capable of measuring the temperature to within 0,5 °C.

NOTE This requirement is imposed because the wave propagation velocity in the coupling fluid is

temperature sensitive.
6.2 Ultrasonic transducers versus specimen holder

The ultrasonic transducers holder or the specimen holder shall allow a rotation to cover the range of

angles of incidence θ between 0° and 90°. Additionally it shall allow for discrete settings of the azimuthal

angle ± of 0°, 45° and 90°. The accuracy in the measurement of the angles θ and ψ shall be better than

0,1° and 1° respectively.

The transducers should be mounted in such a way that their relative position remains fixed during the test.

6.3 Transducers

Use piezoelectric broad-band transducers adapted to the coupling fluid and able to generate longitudinal

ultrasonic waves. Two transducers with similar specifications (central frequency, bandwidth) are used

as emitter and receiver.
6.4 Pulse generator

The pulse generator shall be selected in accordance with the characteristics of the transducers.

It shall be able to generate short-duration (< 1 µs) sinusoidal pulses of voltage sufficient to provide a

mechanical pulse through the transducer. The frequency of the exciting pulse shall be chosen such as

described in 9.1.

The interval between consecutive pulses shall be long compared with the travel time being recorded,

typically greater than 1 ms, so that all signals from the preceding pulse have been dissipated before

initiating the next.
© ISO 2015 – All rights reserved 7
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ISO/DIS 18610:2015(E)
6.5 Signal recording system

Use any system, for instance: digital oscilloscope, with a minimum sampling frequency of 100 MHz

that allows the recording of emitted and received signals. The signal recording system is designed in

order to allow to see on the display the generated and the detected pulses on the same time-base and to

determine the time-gap separating these two events.
7 Test specimens

The choice of test specimen geometry depends on the nature of the material and the reinforcement

structure. The thickness shall be large enough to allow separation of the echoes of the quasi longitudinal

QL and quasi transverse QT waves, and shall be representative of the material. The largest possible

thickness is recommended, at least five times the size of the representative volume element (RVE) in the

direction of propagation of the wave. The other dimensions of the test specimen shall be at least twice

the diameter of the transducer. A specimen with parallel faces is recommended. The plane parallelism

of the two faces shall be better than 0,1.
8 Test specimen preparation

The material symmetry axes shall be identified. If machining is required, it shall be performed in such a

way that the material symmetry axes remain known at all times.

Machining procedures that do not cause damage to the test specimens shall be clearly defined and

recorded. These procedures shall be followed during machining of the test specimens.

NOTE Usually, plate test specimens are cut with their longitudinal axis coinciding with one of the principal

directions of the reinforcement.

One test specimen is sufficient to perform the test. Multiple measurements can be done on a single

test specimen.

Care shall be taken to avoid chemical interaction between the coupling fluid and the test specimen

9 Test procedure
9.1 Choice of frequency

The selection of the appropriate frequency is critical for the application of the method. The frequency

shall be sufficiently low to ensure that the measurement is representative.

NOTE 1 An initial selection of f < 02, , where d is the characteristic length of the RVE in the direction of

normal incidence, is proposed (θ = 0).

Where d is the characteristic length of the RVE in the direction of normal incidence (θ = 0) and V the

propagation velocity inside the specimen and in that direction, is proposed.

NOTE 2 Because of the inverse relationship between wavelength λ and frequency f ( f = ), this corresponds

to a wavelength λ of at least 5d.
For the selected frequency the following additional criteria should be met:

a) measurable amplitude of the QL wave under normal incidence θ = 0. If the amplitude is too small,

the frequency shall be decreased;

b) time separation of the waves QL and QT when varying the angle of incidence θ [see Figure 4 b)]. This

is promoted by increasing the frequency.
8 © ISO 2015 – All rights reserved
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ISO/DIS 18610:2015(E)
NOTE 3 A minimum frequency of is proposed.

Because the frequency requirements for meeting the three mentioned criteria may be conflicting, there

are cases where the method is not applicable. In these cases the only remaining solution is to increase

the specimen thickness beyond the minimum thickness stipulated in Clause 7.

NOTE 4 For example for a 2D SiC/SiC with a RVE of 0,5 mm (requiring a minimum test specimen thickness of

2,5 mm in accordance with Clause 7), the transducer frequency, in order for the measurement to be representative,

is lower than 2,25 MHz (corresponding to wave velocities of around 5 000 m/s). On the other hand for obtaining

mode separation, the frequency is higher than = 3MHz . The method can therefore not be applied for the

given thickness of 2,5 mm. An increase in thickness to 3,3 mm allows mode separation at a frequency of 2,25 MHz.

9.2 Establishment of the test temperature

Measure the temperature of the coupling fluid at a location between the transducers in the vicinity of

the future position of the test specimen. Perform the reference measurement in accordance with 9.3.

Perform the test in accordance with 9.4.
9.3 Reference test without test specimen

Record the signals from the emitter and from the receiver versus time without a test specimen mounted.

9.4 Measurement with the specimen
9.4.1 Measurement of the bulk density and of the thickness
9.4.1.1 Measurement of the bulk density
Measure the bulk density in accordance with EN 1389.
9.4.1.2 Measurement of the thickness

Measure the thickness in three positions on the test area with a calliper with an accuracy of 0,02 mm in

accordance with ISO 3611.
9.4.2 Mounting of the specimen

Mount the test specimen in the test specimen holder. Measure the temperature in the vicinity of the test

specimen. Make sure that the temperature falls within ± 0,5 °C from that of the reference measurement.

The specimen shall be oriented perpendicularly to the incoming beam. The accuracy of the

perpendicularity between the beam and the specimen shall be 0,1.
The test specimen shall be mounted in such a way that
...

NORME ISO
INTERNATIONALE 18610
Première édition
2016-09-15
Céramiques techniques (céramiques
avancées, céramiques techniques
avancées) — Propriétés mécaniques
des céramiques composites à
température ambiante sous air
à pression atmosphérique —
Détermination des propriétés
élastiques par méthode ultrasonore
Fine ceramics (advanced ceramics, advanced technical ceramics) —
Mechanical properties of ceramic composites at ambient temperature
in air atmospheric pressure — Determination of elastic properties by
ultrasonic technique
Numéro de référence
ISO 18610:2016(F)
ISO 2016
---------------------- Page: 1 ----------------------
ISO 18610:2016(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2016, Publié en Suisse

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni utilisée

sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie, l’affichage sur

l’internet ou sur un Intranet, sans autorisation écrite préalable. Les demandes d’autorisation peuvent être adressées à l’ISO à

l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2016 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 18610:2016(F)
Sommaire Page

Avant-propos ..............................................................................................................................................................................................................................iv

1 Domaine d’application ................................................................................................................................................................................... 1

2 Références normatives ................................................................................................................................................................................... 1

3 Termes et définitions ....................................................................................................................................................................................... 1

4 Principe .......................................................................................................................................................................................................................... 4

5 Signification et utilisation........................................................................................................................................................................... 6

6 Matériel d’essai ...................................................................................................................................................................................................... 7

6.1 Réservoir d’immersion avec dispositif de mesure de la température..................................................... 7

6.2 Support des traducteurs et de l’objet d’essai ................................................................................................................ 7

6.3 Traducteurs ................................................................................................................................................................................................ 7

6.4 Générateur d’impulsions ................................................................................................................................................................ 7

6.5 Système d’enregistrement et d’affichage des signaux .......................................................................................... 7

7 Objet d’essai .............................................................................................................................................................................................................. 7

8 Préparation des objets d’essai ............................................................................................................................................................... 8

9 Mode opératoire de l’essai ......................................................................................................................................................................... 8

9.1 Choix de la fréquence ........................................................................................................................................................................ 8

9.2 Réglage de la température d’essai .......................................................................................................................................... 9

9.3 Essai témoin sans objet d’essai ................................................................................................................................................. 9

9.4 Mesure en présence de l’objet d’essai ................................................................................................................................. 9

9.4.1 Détermination de la masse volumique apparente et de l’épaisseur ................................... 9

9.4.2 Montage de l’objet d’essai ........................................................................................................................................ 9

9.4.3 Acquisition de différents angles d’incidence ........................................................................................... 9

10 Calcul .............................................................................................................................................................................................................................10

10.1 Retard ...........................................................................................................................................................................................................10

10.2 Calcul des vitesses de propagation .....................................................................................................................................10

10.3 Calcul de l’angle réfracté, θ ........................................................................................................................................... ..........10

10.4 Identification des constantes élastiques, (C ) ...........................................................................................................11

10.4.1 Considérations fondamentales .........................................................................................................................11

10.4.2 Calcul de C ....................................................................................................................................................................12

10.4.3 Calcul de C , C et C .........................................................................................................................................12

22 23 44

10.4.4 Calcul de C , C et C .........................................................................................................................................12

11 13 55

10.4.5 Calcul de C et C ....................................................................................................................................................13

12 66

10.5 Tracés polaires des courbes de vitesse ...........................................................................................................................14

10.6 Calcul de l’écart quadratique et de l’intervalle de confiance ........................................................................14

10.7 Calcul des constantes de l’ingénieur .................................................................................................................................15

11 Validité de l’essai ...............................................................................................................................................................................................15

11.1 Mesures ......................................................................................................................................................................................................15

11.2 Critère de validité pour la fiabilité des composantes (C ) de la matrice de rigidité ................15

12 Rapport d’essai ....................................................................................................................................................................................................15

Annexe A (informative) Exemple de présentation des résultats pour un matériau avec

symétrie orthotrope ......................................................................................................................................................................................17

Bibliographie ...........................................................................................................................................................................................................................19

© ISO 2016 – Tous droits réservés iii
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ISO 18610:2016(F)
Avant-propos

L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes

nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est

en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.

L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents

critères d’approbation requis pour les différents types de documents ISO. Le présent document a été

rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www.

iso.org/directives).

L’attention est appelée sur le fait que certains des éléments du présent document peuvent faire l’objet de

droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de

brevets reçues par l’ISO (voir www.iso.org/brevets).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un

engagement.

Pour une explication de la signification des termes et expressions spécifiques de l’ISO liés à l’évaluation

de la conformité, ou pour toute information au sujet de l’adhésion de l’ISO aux principes de l’Organisation

mondiale du commerce (OMC) concernant les obstacles techniques au commerce (OTC), voir le lien

suivant: www.iso.org/iso/fr/avant-propos.html

Le comité chargé de l’élaboration du présent document est l’ISO/TC 206, Céramiques techniques.

iv © ISO 2016 – Tous droits réservés
---------------------- Page: 4 ----------------------
NORME INTERNATIONALE ISO 18610:2016(F)
Céramiques techniques (céramiques avancées, céramiques
techniques avancées) — Propriétés mécaniques des
céramiques composites à température ambiante sous air à
pression atmosphérique — Détermination des propriétés
élastiques par méthode ultrasonore
1 Domaine d’application

Le présent document spécifie une méthode ultrasonore pour déterminer les composantes du tenseur

d’élasticité des composites à matrice céramique à température ambiante. Les modules de Young, les

modules de cisaillement et les coefficients de Poisson peuvent être déterminés à partir des composantes

du tenseur d’élasticité.

Le présent document s’applique aux composites à matrice céramique à renfort fibreux continu

unidirectionnels (1D), bidirectionnels (2D) et tridirectionnels (× D, avec 2 < × ≤ 3), qui ont au minimum

une symétrie orthotrope et dont les axes de symétrie sont connus.

Cette méthode est uniquement applicable lorsque la longueur d’onde ultrasonore utilisée est supérieure

à l’épaisseur du volume élémentaire représentatif, ce qui impose une limite supérieure à la gamme de

fréquences des traducteurs utilisés.

NOTE Les propriétés obtenues au moyen de cette méthode peuvent ne pas être comparables avec les modules

obtenus par les méthodes décrites dans l’ISO 15733, l’ISO 20504 et l’EN 12289.
2 Références normatives

Les documents suivants cités dans le texte constituent, pour tout ou partie de leur contenu, des

exigences du présent document. Pour les références datées, seule l’édition citée s’applique. Pour les

références non datées, la dernière édition du document de référence s’applique (y compris les éventuels

amendements).

ISO 3611, Spécification géométrique des produits (GPS) — Équipement de mesurage dimensionnel:

Micromètres d’extérieur — Caractéristiques de conception et caractéristiques métrologiques

ISO/IEC 17025, Exigences générales concernant la compétence des laboratoires d’étalonnages et d’essais

EN 1389, Céramiques techniques avancées — Céramiques composites — Propriétés physiques —

Détermination de la masse volumique et de la porosité apparente
3 Termes et définitions

Pour les besoins du présent document, les termes et définitions donnés dans le CEN/TR 13233 ainsi que

les suivants s’appliquent.

L’ISO et l’IEC gèrent des bases de données terminologiques destinées à être utilisées pour la

normalisation disponibles aux adresses suivantes:
— IEC Electropedia: http://www.electropedia.org/.
— Plateforme de consultation en ligne de l’ISO: http://www.iso.org/obp.
© ISO 2016 – Tous droits réservés 1
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ISO 18610:2016(F)
3.1
relations contrainte-déformation pour un matériau orthotrope

comportement anisotrope élastique d’un corps solide homogène décrit par le tenseur d’élasticité du

quatrième ordre (C ), représenté en notation abrégée par une matrice carrée symétrique (6 × 6)

ijkl

Note 1 à l’article: Si le matériau présente au moins une symétrie orthotrope, son comportement élastique

est entièrement caractérisé par neuf composantes de rigidité indépendantes (C ) de la matrice de rigidité

(C ), qui relie les contraintes aux déformations, ou, de façon équivalente, par neuf composantes de souplesse

indépendantes (S ) de la matrice de souplesse (S ), qui relie les déformations aux contraintes. Les matrices de

ij ij
rigidité et de souplesse sont l’inverse l’une de l’autre.

Si le système de coordonnées de référence est pris selon les axes de symétrie, la matrice de rigidité (C )

et la matrice de souplesse (S ) peuvent être écrites comme suit:
     
σ C C C 00 0 ε
1 11 12 13 1
     
σ CC C 000 εε
     
2 12 22 23 2
     
σ C CC 000 ε
3 113 23 33 3
     
σ 000 C 00 ε
     
4 44 4
     
σ 000 00C ε
5 55 5
     
σ  000 00 C  ε 
6 66 6
     
     
ε SS S 00 0 σ
1 11 12 13 1
     
ε SS S 000 σσ
     
2 12 22 23 2
     
ε S SS 000 σ
3 113 23 33 3
     
ε 000 S 00 σ
     
4 44 4
     
ε 000 00S σ
5 55 5
     
ε  000 00 S  σ 
6 66 6
     

Note 2 à l’article: Pour les symétries de niveau supérieur à la symétrie orthotrope, les matrices (C ) et (S ) ont la

ij ij
même forme que ci-dessus. Seul le nombre de composantes indépendantes diminue.
3.2
constantes de l’ingénieur

composantes de la matrice de souplesse d’un matériau orthotrope exprimées en termes de constantes

de l’ingénieur:
 
−ν −ν
121 31
00 0
 
11 33
 
−ν −ν
12 1 32
 00 0 
11 33
 
−νν
 
13 23 1
00 0
 E 
 
E E
S =
11 33
 
 
00 0 00
 
 
00 00 0
 
 
00 00 0
 
 12

E , E et E sont les modules d’élasticité dans les directions 1, 2 et 3 respectivement;

11 22 33
G , G et G sont les modules de cisaillement dans les plans correspondants;
12 13 23
ν , ν , ν sont les coefficients de Poisson correspondants.
12 13 23
2 © ISO 2016 – Tous droits réservés
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ISO 18610:2016(F)
3.3
angle d’incidence

angle formé par la direction 3 perpendiculaire à la face avant de l’éprouvette et la direction n de l’onde

incidente
Note 1 à l’article: Voir Figures 1 et 2.
3.4
angle réfracté

angle formé par la direction 3 perpendiculaire à la face avant de l’éprouvette et la direction n de la

propagation de l’onde à l’intérieur de l’éprouvette
Note 1 à l’article: Voir Figures 1 et 2.
3.5
angle azimutal

angle formé par le plan d’incidence (3, n ) et le plan (2, 3) où n correspond au vecteur orienté suivant

i i

l’onde de plan incident et la direction 2 correspond à l’un des axes de symétrie du matériau

Note 1 à l’article: Voir Figure 1.
Figure 1 — Définition des angles
Figure 2 — Propagation dans le plan d’incidence
© ISO 2016 – Tous droits réservés 3
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ISO 18610:2016(F)
3.6
premier angle critique

angle d’incidence θ qui génère un angle à 90 degrés de l’angle de réfraction d’une onde quasi

longitudinale
3.7
vecteur unitaire

vecteur de longueur 1 orienté suivant la direction de propagation de l’onde de plan incident à l’intérieur

de l’éprouvette, ses composantes étant n (k = 1, 2, 3):
n =sinsθψin
1 r
n =sincθψos
2 r
n =cosθ
3 r
Note 1 à l’article: Voir Figures 1 et 2.
3.8
vitesse de propagation
V(n)

vitesse de phase d’une onde plane à l’intérieur de l’éprouvette en fonction du vecteur unitaire n (c’est-à-

dire en fonction de ψ et θ )
Note 1 à l’article: V est la vitesse de propagation dans le liquide de couplage.
3.9
retard
δt(n)

différence entre le temps de vol de l’onde lorsque l’éprouvette est en place et le temps de vol de l’onde

dans le liquide de couplage en l’absence de l’éprouvette dans la même configuration des traducteurs, en

fonction du vecteur unitaire n
3.10
masse volumique

rapport de la masse du matériau sans porosité à son volume total incluant la porosité

4 Principe

La détermination des propriétés élastiques consiste à calculer les coefficients de l’équation de la

propagation d’une onde plane élastique, à partir d’un ensemble de mesures de la vitesse correctement

choisies selon des directions connues.

Une éprouvette mince à faces parallèles est immergée dans un liquide de couplage acoustique (par

exemple de l’eau), voir Figure 3. L’éprouvette est placée entre un émetteur (T) et un récepteur (R) qui

sont reliés rigidement l’un à l’autre et ont deux degrés de liberté en rotation. En utilisant un traitement

approprié du signal, la vitesse de propagation de chaque onde dans l’éprouvette est calculée.

4 © ISO 2016 – Tous droits réservés
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ISO 18610:2016(F)
θ i
Légende
1 entraînement en rotation
2 objet d’essai
3 générateur d’impulsions
4 oscilloscope numérique
5 micro-ordinateur
Figure 3 — Dispositif d’essai ultrasonore

Selon l’angle d’incidence, l’onde créée par l’impulsion envoyée par l’émetteur T est réfractée dans le

matériau en une (une onde quasi longitudinale QL, ou une onde quasi transversale QT), deux (QL + QT

ou deux ondes quasi transversales QT , QT ) ou trois ondes de volume (QL + QT + QT ) qui se propagent

1 2 1 2
dans le solide à différentes vitesses et dans différentes directions.

Le récepteur R recueille une, deux ou trois impulsions correspondant à chacune de ces ondes.

La différence entre le temps de vol des diverses ondes et le temps de vol de l’impulsion émise dans le

liquide de couplage en l’absence de l’objet d’essai est mesurée. La méthode d’évaluation est fondée sur la

mesure de la différence des temps de vol de l’onde quasi longitudinale et d’une onde quasi transversale

ou des deux ondes quasi transversales, et est uniquement valide lorsque les ondes QL et QT sont séparées

de façon appropriée, voir Figure 4.
© ISO 2016 – Tous droits réservés 5
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ISO 18610:2016(F)
05 10 15 20 25
Légende Légende
Y amplitude Y amplitude
X angle d’incidence X temps
NOTE Les deux ondes QL et QT sont présentes et
peuvent être distinguées dans la zone positive mais
se recouvrent légèrement dans la zone négative.
a) Amplitude des ondes QL et QT en fonc- b) Oscillogramme temporel des ondes

tion de l’angle d’incidence avec recouvrement QL et QT à un angle d’incidente, θ ,

dans la zone de θ proche de l’angle critique, θ
c c

Figure 4 — Exemple de recouvrement partiel des ondes QL et QT à un angle d’incidence θ

À partir des vitesses de propagation, les composantes du tenseur d’élasticité sont obtenues par une

analyse de régression des moindres carrés qui réduit au minimum les erreurs résiduelles des équations

de la propagation des ondes.

Les modules de Young, les modules de cisaillement et les coefficients de Poisson sont déterminés à

partir de ces composantes.
5 Signification et utilisation

Deux constantes seulement (coefficients de Lamé, module de Young et coefficient de Poisson, modules

de Young et de cisaillement, vitesses d’ondes longitudinales et transversales) suffisent pour décrire

complètement le comportement élastique d’un corps solide isotrope. Lorsque l’anisotropie, qui est

une caractéristique spécifique des matériaux composites, doit être prise en compte, il est nécessaire

d’utiliser un tenseur d’élasticité comportant un plus grand nombre de coefficients indépendants.

Alors que les méthodes mécaniques conventionnelles ne permettent qu’une identification partielle de

l’élasticité des corps anisotropes, les méthodes ultrasonores permettent une évaluation plus exhaustive

des propriétés élastiques de ces matériaux, en particulier les modules d’élasticité transversale et les

modules de cisaillement pour les éprouvettes minces.

La réussite de l’application de la méthode dépend fondamentalement d’un choix approprié de la

fréquence centrale des traducteurs. La fréquence doit être suffisamment basse pour que la mesure soit

représentative de la réponse du volume élémentaire, mais en même temps suffisamment haute pour

obtenir une séparation entre les ondes QL et QT.
6 © ISO 2016 – Tous droits réservés
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ISO 18610:2016(F)

La détermination des propriétés élastiques par la méthode ultrasonore décrite dans la présente norme

est fondée sur une mesure non destructive et dynamique des vitesses de propagation des ondes. La

détermination des valeurs des modules de Young, des modules de cisaillement et des coefficients de

Poisson nécessite une seule éprouvette.
6 Matériel d’essai
6.1 Réservoir d’immersion avec dispositif de mesure de la température

Il convient que la température du liquide de couplage dans le réservoir d’immersion reste constante à

±0,5 °C près pendant toute la durée de l’essai.

Le dispositif de mesure de la température doit être capable de mesurer la température à 0,5 °C près.

Cette exigence résulte du fait que la vitesse de propagation de l’onde dans le liquide de couplage est très

sensible à la température.
6.2 Support des traducteurs et de l’objet d’essai

Le support des traducteurs ultrasonores ou le support de l’objet d’essai doit permettre une rotation

couvrant la plage des angles d’incidence θ entre 0° et 90°. De plus, il doit permettre des réglages discrets

de l’angle azimutal à ± 0°, 45° et 90°. L’exactitude de la mesure des angles θ et ψ doit être meilleure que

0,1° et 1°, respectivement.

Les traducteurs doivent être montés de façon que leur position relative reste fixe durant l’essai.

6.3 Traducteurs

Des traducteurs piézoélectriques à large bande adaptés au liquide de couplage et capables de

produire des ondes ultrasonores longitudinales doivent être utilisés. Deux traducteurs présentant des

spécifications similaires (par exemple fréquence centrale, largeur de bande) doivent être utilisés, l’un

comme émetteur, l’autre comme récepteur.
6.4 Générateur d’impulsions

Le générateur d’impulsions doit être choisi en fonction des caractéristiques des traducteurs.

Il doit pouvoir générer des impulsions sinusoïdales de courte durée (<1 µs), d’une tension suffisante

pour générer une impulsion mécanique par le traducteur. La fréquence de l’impulsion d’excitation doit

être choisie tel que décrit en 9.1.

Comparé au temps de vol enregistré, l’intervalle entre des impulsions consécutives doit être long, un

intervalle type étant supérieur à 1 ms, afin que tous les signaux de l’impulsion précédente se dissipent

avant la production de la nouvelle impulsion.
6.5 Système d’enregistrement et d’affichage des signaux

Utiliser tout système, par exemple un oscilloscope numérique, ayant une fréquence d’échantillonnage

minimale de 100 MHz qui permet d’enregistrer les signaux transmis et reçus. Le système

d’enregistrement des signaux est conçu pour permettre de lire à l’écran les impulsions émises et les

impulsions détectées sur la même base temporelle et pour déterminer le laps de temps écoulé entre ces

deux événements.
7 Objet d’essai

Le choix de la géométrie de l’objet d’essai dépend du matériau et de la structure du renfort. L’épaisseur

doit être suffisante pour permettre la séparation des échos des ondes quasi longitudinale QL et

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ISO 18610:2016(F)

quasi transversale QT et doit être représentative du matériau. La plus grande épaisseur possible est

recommandée, et doit être au moins de cinq fois la dimension du volume élémentaire représentatif

(VER) dans la direction de propagation de l’onde. Les autres dimensions de l’objet d’essai doivent être

au moins égales au double du diamètre du traducteur. Un objet d’essai à faces parallèles est obligatoire.

Le parallélisme des deux faces doit être meilleur que 0,1 mm.
8 Préparation des objets d’essai

Les axes de symétrie du matériau doivent être identifiés. Si un usinage est exigé, il doit être effectué de

sorte que les axes de symétrie du matériau demeurent connus en tout temps.

Les procédés d’usinage qui n’endommagent pas les objets d’essai doivent être clairement définis et

enregistrés. Ces procédés doivent être suivis durant l’usinage des objets d’essai.

NOTE D’ordinaire, les objets d’essai plats sont découpés de sorte que leur axe longitudinal coïncide avec

l’une des directions principales du renfort.

Un objet d’essai suffit pour effectuer l’essai. Il est possible d’effectuer plusieurs mesures avec un seul

objet d’essai.

Des précautions doivent être prises pour éviter l’interaction chimique entre le liquide de couplage et

l’objet d’essai.
9 Mode opératoire de l’essai
9.1 Choix de la fréquence

La sélection de la fréquence appropriée est décisive pour l’application de la méthode. La fréquence, f,

doit être suffisamment basse pour assurer la représentativité de la mesure.

NOTE 1 Une sélection initiale de f < 02, , où d est la longueur caractéristique du VER dans la direction

d’incidence normale (θ = 0) et V la vitesse de propagation à l’intérieur de l’éprouvette et dans cette direction est

proposée.

NOTE 2 En raison de la relation inverse entre la longueur d’onde λ et la fréquence f ( f = ), ce choix de

fréquence correspond à une longueur d’onde λ égale au moins à 5d.

Il convient que la fréquence choisie réponde aux critères supplémentaires suivants:

a) une amplitude mesurable de l’onde QL sous l’incidence normale θ = 0. Si l’amplitude est trop faible,

la fréquence doit être diminuée;

b) une séparation temporelle des ondes QL et QT lors de la variation de l’angle d’incidence θ [voir

Figure 4 b)]. Cette séparation est favorisée par l’augmentation de la fréquence.
Une fréquence minimale de est recommandée.
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ISO 18610:2016(F)

Les exigences relatives à la fréquence destinées à satisfaire aux trois critères susmentionnés pouvant

être antagonistes, la méthode n’est pas applicable dans certains cas. La seule solution consiste alors à

augmenter l’épaisseur de l’objet d’essai, au-delà de l’épaisseur minimale stipulée dans l’Article 7.

NOTE 3 Par exemple, pour un SiC/SiC 2D avec un VER de 0,5 mm (exigeant une épaisseur minimale de l’objet

d’essai de 2,5 mm conformément à l’Article 7), la fréquence d’essai, pour une mesure qui soit représentative, est

inférieure à 2,25 MHz (ce qui correspond à des vitesses de propagation de l’onde d’environ 5 000 m/s). D’autre

part, pour obtenir la séparation des modes, la fréquence est supérieure à = 3MHz . La méthode ne peut donc

être appliquée pour une épaisseur donnée de 2,5 mm. Une augmentation de l’épaisseur à 3,3 mm permet de

réaliser la séparation des modes pour une fréquence de 2,25 MHz.
9.2 Réglage de la température d’essai

Mesurer la température du liquide de couplage à un emplacement situé entre les traducteurs, au

voisinage de la position future de l’éprouvette. Réaliser la mesure de référence conformément à 9.3.

Effectuer l’essai conformément à 9.4.
9.3 Essai témoin sans objet d’essai

Enregistrer les signaux de l’émetteur et du récepteur en fonction du temps, en l’absence d’objet d’essai.

9.4 Mesure en p
...