SIST ENV 14186:2007
(Main)Advanced technical ceramics - Ceramic composites - Mechanical properties at room temperature, determination of elastic properties by an ultrasonic technique
Advanced technical ceramics - Ceramic composites - Mechanical properties at room temperature, determination of elastic properties by an ultrasonic technique
This ENV specifies an ultrasonic method to determine the components of the elasticity tensor of ceramic matrix composite materials at room temperature. Young moduli, shear moduli and Poisson coefficients, can be determined from the components of the elasticity tensor. This standard applies to ceramic matrix composites with a continuous fibre reinforcement: unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2< x 3) which have at least orthotropic symmetry, and whose material symmetry axes are known. This method is applicable only when the ultrasonic wave length 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 avancées - Céramiques composites - Propriétés mécaniques a température ambiante, détermination des propriétés élastiques par une méthode ultrasonore
La présente ENV spécifie une méthode ultrasonore pour déterminer les composants 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 composants du tenseur d'élasticité.
Cette norme s'applique aux composites à matrice céramique à renfort fibreux continu unidirectionnels (1D), bidirectionnels (2D) et tridirectionnels (xD, avec 2 x 3), qui ont au minimum une symétrie orthotrope et dont les axes de symétrie sont connus.
Cette méthode est applicable uniquement 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 transducteurs 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'EN 658-1, l'EN 658-2 et l'ENV 12289.
Sodobna tehnična keramika - Keramični kompoziti - Mehanske lastnosti pri sobni temperaturi, določanje upogibnih lastnosti z ultrazvočno tehniko
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Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2007
6RGREQDWHKQLþQDNHUDPLND.HUDPLþQLNRPSR]LWL0HKDQVNHODVWQRVWLSULVREQL
WHPSHUDWXULGRORþDQMHXSRJLEQLKODVWQRVWL]XOWUD]YRþQRWHKQLNR
Advanced technical ceramics - Ceramic composites - Mechanical properties at room
temperature, determination of elastic properties by an ultrasonic technique
Céramiques techniques avancées - Céramiques composites - Propriétés mécaniques a
température ambiante, détermination des propriétés élastiques par une méthode
ultrasonore
Ta slovenski standard je istoveten z: ENV 14186:2002
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN PRESTANDARD
ENV 14186
PRÉNORME EUROPÉENNE
EUROPÄISCHE VORNORM
August 2002
ICS 81.060.30
English version
Advanced technical ceramics - Ceramic composites -
Mechanical properties at room temperature, determination of
elastic properties by an ultrasonic technique
Hochleistungskeramik - Keramische Verbundwerkstoffe -
Mechanische Eigenschaften bei Raumtemperatur,
Bestimmung von elastischen Eigenschaften mittels
Ultraschallwellen
This European Prestandard (ENV) was approved by CEN on 13 July 2001 as a prospective standard for provisional application.
The period of validity of this ENV is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the ENV can be converted into a European Standard.
CEN members are required to announce the existence of this ENV in the same way as for an EN and to make the ENV available promptly
at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the ENV) until the final
decision about the possible conversion of the ENV into an EN is reached.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2002 CEN All rights of exploitation in any form and by any means reserved Ref. No. ENV 14186:2002 E
worldwide for CEN national Members.
Contents
Foreword.3
1 Scope .4
2 Normative references .4
3 Principle.4
4 Significance and use .7
5 Terms and definitions and symbol.7
6 Apparatus .10
6.1 Ultrasonic tank with thermostatic control.10
6.2 Temperature measurement device .10
6.3 Test specimen holder .10
6.4 Transducers.10
6.5 Transducer holders .10
6.6 Pulse generator.10
6.7 Signal recording system .11
7 Test specimens .11
8 Test Specimen preparation.11
9 Test procedure .11
9.1 Choice of frequency .11
9.2 Establishment of the test temperature. .12
9.3 Reference test without test specimen .12
9.4 Measurement with the specimen.12
9.4.1 Measurement of the bulk density and of the thickness.12
9.4.2 Mounting of the specimen .12
9.4.3 Acquisition of different angles of incidence.12
10 Calculation.13
10.1 Delay.13
10.2 Calculation of the propagation velocities .13
10.3 Calculation of the refracted angle qq.14
r
10.4 Identification of the elastic constants C .14
ij
10.4.1 Basic considerations.14
C
10.4.2 Calculation of .15
10.4.3 Calculation of C , C and C .15
22 23 44
10.4.4 Calculation of C , C and C .16
11 13 55
10.4.5 Calculation of C and C .16
12 66
10.5 Back calculation of the phase velocities.17
10.6 Polar plots of the velocity curves.17
10.7 Calculation of the quadratic deviation.17
10.8 Calculation of the engineering constants .18
11 Test validity .18
11.1 Measurements.18
11.2 Criterion of validity for the reliability of the C components .18
ij
12 Test report .19
(informative)
Annex A Example of a presentation of the results for a material with orthothropic
symmetry .20
Bibliography .22
Foreword
This document (ENV 14186:2002) has been prepared by Technical Committee CEN/TC 184 "Advanced technical
ceramics", the secretariat of which is held by BSI.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this European Prestandard: Austria, Belgium, Czech Republic, Denmark, Finland,
France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain,
Sweden, Switzerland and the United Kingdom.
1 Scope
This ENV specifies an ultrasonic method to determine the components of the elasticity tensor of ceramic matrix
composite materials at room temperature. Young moduli, shear moduli and Poisson coefficients, can be
determined from the components of the elasticity tensor.
This standard applies to ceramic matrix composites with a continuous fibre reinforcement: unidirectional (1D),
bidirectional (2D), and tridirectional (xD, with 2< x £ 3) which have at least orthotropic symmetry, and whose
material symmetry axes are known.
This method is applicable only when the ultrasonic wave length 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 may not be comparable with moduli obtained by EN 658-1, ENV 658-2 and
ENV 12289.
2 Normative references
This European Prestandard incorporates by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed hereafter. For
dated references, subsequent amendments to or revisions of any of these publications apply to this European
Prestandard only when incorporated in it by amendment or revision. For undated references the latest edition of the
publication referred to applies.
ENV 1389, Advanced technical ceramics – Composite ceramics – Physical properties – Determination of density
and of apparent porosity.
ENV 13233:1998, Advanced technical ceramics – Composite ceramics – Notations and symbols.
ISO 3611, Micrometer callipers for external measurements.
ISO 653, Long-solid-stem thermometers for precision use.
3 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 planparallel faces is immersed in an acoustically coupling fluid (e.g. water) – see Figure 1.
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.
Key
1 Rotation drive
2 Test specimen
3 Pulse generator
4 Digital Oscilloscope
5 Micro-computer
Figure 1 — Ultrasonic test assembly
Depending on the angle of incidence, the pulse sent by the emitter E is refracted within the material in one, two or
three bulk waves (one quasi longitudinal wave QL, one quasi transverse wave QT, or two quasi transverse waves
QT , QT ) that propagate in the solid at different velocities and in different directions. The receiver R collects one,
1 2
two or three pulses, corresponding to each of these waves. The difference in 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 difference of the quasilongitudinal and one or both
quasitransverse waves, and is only valid when the QL and the QT waves are appropriately separated
(see Figure 2).
Key
1 Amplitude
2 Incidence angle
Figure 2a) — Amplitude of the QL and QT waves as a function of the incidence angle
Key
1 Amplitude
2Time
Figure 2b) — Temporal waveform of the overlapping QL and QT waves at an incidence angle qq
i
Figure 2 — Overlapping of QL and QT waves at an incidence angle qq
i
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 moduli, shear moduli and Poisson coefficients are determined from these components.
4 Significance and use
Only two constants (Lamé's coefficients or Young modulus and Poisson coefficient) are sufficient in order to fully
describe the elastic behaviour of an isotropic body. When anisotropy, which is a specific feature of composite
materials, has to 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 ela
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