ISO 17282:2004
(Main)Plastics — Guide to the acquisition and presentation of design data
Plastics — Guide to the acquisition and presentation of design data
ISO 17282:2004 gives guidelines for the acquisition and presentation of data that can be used for design with plastics. Emphasis is given to the acquisition of data needed by computerised methods for design. It includes data needed for the analysis of the flow of polymer melts during the manufacture of a component as well as data needed for the prediction of mechanical performance of the component in service. The data requirements cover design with unfilled plastics as well as filled, short-fibre reinforced and continuous-fibre reinforced materials.
Plastiques — Lignes directrices pour l'acquisition et la présentation de caractéristiques de conception
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 17282
First edition
2004-06-01
Corrected version
2007-02-01
Plastics — Guide to the acquisition and
presentation of design data —
Plastiques — Lignes directrices pour l'acquisition et la présentation de
caractéristiques de conception
Reference number
©
ISO 2004
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...
INTERNATIONAL ISO
STANDARD 17282
First edition
2004-06-01
Corrected version
2007-02-01
Plastics — Guide to the acquisition and
presentation of design data
Plastiques — Lignes directrices pour l'acquisition et la présentation de
caractéristiques de conception
Reference number
©
ISO 2004
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2004
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
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ii © ISO 2004 – All rights reserved
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Symbols . 3
3.1 Test variables . 3
3.2 Material properties for stress analysis (see Tables 2 and 3). 3
3.3 Failure properties (see Table 4) . 4
3.4 Material properties for processing simulation (see Tables 3, 4 and 5) . 5
4 Data needed for design . 6
4.1 General. 6
4.2 Design for thermomechanical performance . 6
4.2.1 The design process . 6
4.2.2 Design data for thermomechanical performance. 7
4.3 Design for processing analysis. 10
4.3.1 Processing simulation. 10
4.3.2 Data for simulation of injection moulding. 10
4.3.3 Data for simulation of extrusion. 12
4.3.4 Data for simulation of blow moulding, blown film extrusion and thermoforming. 12
5 Determination of design data . 13
5.1 General. 13
5.2 Data acquisition for design for mechanical performance . 13
5.3 Data acquisition for design for processing . 14
Annex A (informative) Illustrations of the application of finite element analyses to plastics
components. 19
Annex B (informative) Application of processing simulation analysis for plastics . 48
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 17282 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 2, Mechanical
properties.
This corrected version of ISO 17282:2004 incorporates the following corrections:
in paragraph 4 of the Introduction, the references to Tables 6 and 7 have been corrected;
Clause 2 (normative references) has been updated, the only important change being the replacement of
ISO 6252 (which has been withdrawn) by ISO 22088-2;
in the heading to 3.4, the references to the tables have been corrected;
in Table 12, ISO 6252 has been replaced by ISO 22088-2 (twice);
Equations (A.6) and (A.7), which were missing, have been inserted;
throughout the document, a number of symbols and their subscripts have been corrected;
a number of minor editorial improvements have been made.
iv © ISO 2004 – All rights reserved
Introduction
Plastics and composites are increasingly being used in load-bearing applications where they compete with
traditional materials such as steels and aluminium. In these applications, it is important to achieve a confident
knowledge of the safe operating limits of the component through competent design. Computer methods for
design are available, and are continually being improved, that enable predictions to be made of the
performance of plastics under a variety of situations. These situations include mechanical performance under
service loads and environments as well as a flow of the polymer melt during the manufacture of a component.
In order to design effectively with plastics in load-bearing applications, comprehensive data are generally
needed which take into account the effects of time, temperature, rate and environment on properties. A
number of International Standards have been developed that specify how certain data for plastics should be
measured and presented. These are ISO 10350-1 and ISO 10350-2, and ISO 11403-1, ISO 11403-2 and
ISO 11403-3.
The purpose of these standards is to enable comparable data to be measured on different materials from
different sources to aid the process of materials selection. A substantial quantity of data is specified by these
standards and, although not the primary purpose of the standards, some of these data are suitable for design.
However, additional or alternative data will also be needed for many applications.
The purpose of this guide is to augment existing data presentation standards by identifying data that are
needed specifically for design with plastics. The selection of these data is guided by the requirements of
available computer methods for design. Preferred test methods, test specimens and test conditions are
recommended in section 5 for determining these data. For some properties, ISO test methods or specimens
are not yet available. Reference is then made in the Notes to Tables 12 and 13 to suitable procedures for data
acquisition that may become standardised at a later stage.
It is intended that this guide assist the development of databases that will interface with computer methods for
design so that the property data required by these methods can be readily accessed. For certain properties,
some analysis and interpretation of data is needed in order to present information in the form required by the
design analysis. Some procedures for data analysis are described in the annexes.
INTERNATIONAL STANDARD ISO 17282:2004(E)
Plastics — Guide to the acquisition and presentation of design
data
1 Scope
This International Standard gives guidelines for the acquisition and presentation of data that can be used for
design with plastics. Emphasis is given to the acquisition of data needed by computerised methods for design.
It includes data needed for the analysis of the flow of polymer melts during the manufacture of a component
as well as data needed for the prediction of mechanical performance of the component in service. The data
requirements cover design with unfilled plastics as well as filled, short-fibre reinforced and continuous-fibre
reinforced materials.
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.
ISO 294-3, Plastics — Injection moulding of test specimens of thermoplastics materials — Part 3: Small plates
ISO 294-5, Plastics — Injection moulding of test specimens of thermoplastics materials — Part 5: Preparation
of standard specimens for investigating anisotropy
ISO 527-2, Plastics — Determination of tensile properties — Part 2: Test conditions for moulding and
extrusion plastics
ISO 527-4, Plastics — Determination of tensile properties — Part 4: Test conditions for isotropic and
orthotropic fibre-reinforced plastic composites
ISO 527-5, Plastics — Determination of tensile properties — Part 5: Test conditions for unidirectional fibre-
reinforced plastic composites
ISO 899-1, Plastics — Determination of creep behaviour — Part 1: Tensile creep
ISO 1183, Plastics — Methods for determining the density and relative density of non-cellular plastics
ISO 2577, Plastics — Thermosetting moulding materials — Determination of shrinkage
ISO 3167, Plastics — Multipurpose test specimens
ISO 6603-2, Plastics — Determination of puncture impact behaviour of rigid plastics — Part 2: Instrumented
impact test
ISO 6721-2, Plastics — Determination of dynamic mechanical properties — Part 2: Torsion-pendulum method
ISO 6721-3, Plastics — Determination of dynamic mechanical properties — Part 3: Flexural vibration —
Resonance-curve method
ISO 6721-4, Plastics — Determination of dynamic mechanical properties — Part 4: Tensile vibration — Non-
resonance method
ISO 6721-5, Plastics — Determination of dynamic mechanical properties — Part 5: Flexural vibration — Non-
resonance method
ISO 6721-7, Plastics — Determination of dynamic mechanical properties — Part 7: Torsional vibration — Non-
resonance method
ISO 6721-8, Plastics — Determination of dynamic mechanical properties — Part 8: Longitudinal and shear
vibration — Wave propagation method
ISO 6721-10, Plastics — Determination of dynamic mechanical properties — Part 10: Complex shear viscosity
using a parallel-plate oscillatory rheometer
ISO 10350-1, Plastics — Acquisition and presentation of comparable single-point data — Part 1: Moulding
materials
ISO 11357-2, Plastics — Differential scanning calorimetry (DSC) — Part 2: Determination of glass transition
temperature
ISO 11357-3, Plastics — Differential scanning calorimetry (DSC) — Part 3: Determination of temperature and
enthalpy of melting and crystallization
ISO 11357-4, Plastics — Differential scanning calorimetry (DSC) — Part 4: Determination of specific heat
capacity
ISO 11357-5, Plastics — Differential scanning calorimetry (DSC) — Part 5: Determination of characteristic
reaction-curve temperatures and times, enthalpy of reaction and degrees of conversion
ISO 11357-7, Plastics — Differential scanning calorimetry (DSC) — Part 7: Determination of crystallization
kinetics
ISO 11359-2, Plastics — Thermomechanical analysis (TMA) — Part 2: Determination of coefficient of linear
thermal expansion and glass transition temperature
ISO 11403-1, Plastics — Acquisition and presentation of comparable multipoint data — Part 1: Mechanical
properties
ISO 11403-2, Plastics — Acquisition and presentation of comparable multipoint data — Part 2: Thermal and
processing properties
ISO 11443, Plastics — Determination of the fluidity of plastics using capillary and slit-die rheometers
ISO 15310, Fibre-reinforced plastic composites — Determination of the in-plane shear modulus by the plate
twist method
ISO 17744, Plastics — Determination of specific volume as a function of temperature and pressure (pvT
diagram) — Piston apparatus method
ISO 22088-2, Plastics — Determination of resistance to environmental stress cracking (ESC) — Part 2:
Constant tensile load method
2 © ISO 2004 – All rights reserved
3 Symbols
3.1 Test variables
ε tensile strain
NOTE Use of the true strain log (1 + ε) in place of the engineering strain is necessary when engineering strain
e
values exceed about 0,1. Below a strain of 0,1, there is no significant difference between these quantities.
ε tensile strain rate
p
ε plastic component of the tensile strain
NOTE This is used in elastic–plastic models for describing non-linear behaviour.
γ shear strain
γ shear strain rate
p
γ plastic component of the shear strain
t time
σ stress
T temperature
f frequency
ch chemical environment
N number of cycles to failure in a fatigue test
R ratio of minimum to maximum stresses in a fatigue test
T rate of change of temperature
p pressure
p cavity pressure at hold
CH
t hold time
H
h specimen thickness
v slip velocity
s
3.2 Material properties for stress analysis (see Tables 2 and 3)
E tensile modulus obtained from a test at constant strain rate
E E tensile moduli along and transverse to, respectively, the direction of preferred fibre or molecular
,
p n
orientation in a transversely isotropic material
G shear modulus of a transversely isotropic material for stress application in the direction of preferred
p
orientation
D tensile creep compliance
E tensile stress relaxation modulus
R
D , D tensile creep compliances along and transverse to, respectively, the direction of preferred orientation
p n
in a transversely isotropic material
E', E'' tensile storage and loss moduli, respectively
G', G'' shear storage and loss moduli, respectively
σ true tensile yield stress (see Note 4 to Table 12)
T
λ hydrostatic stress sensitivity parameter (see Note 6 to Table 12)
σ , σ tensile yield stresses for loading along and transverse to, respectively, the direction of preferred
Tp Tn
orientation in a transversely isotropic material (see Notes 4 and 9 to Table 12)
σ , σ shear yield stresses for loading along and transverse to, respectively, the direction of preferred
Sp Sn
orientation in a transversely isotropic material (see Note 9 to Table 12)
ν Poisson’s ratio
e
ν elastic component of the Poisson’s ratio
p
ν plastic component of the Poisson’s ratio equal to minus the ratio of the plastic component of the
lateral strain to the plastic component of the axial strain in a specimen under a tensile stress (see
Note 5 to Table 12)
ν Poisson’s ratio for an anisotropic material determined with the uniaxial stress applied along the
pn
direction of preferred orientation
ψ flow parameter
α coefficient of linear thermal expansion
α ,α coefficients of linear thermal expansion parallel and normal to the direction of preferred orientation in
p n
a transversely isotropic material
c specific heat
p
3.3 Failure properties (see Table 4)
σ tensile strength obtained from a test at constant specimen deformation rate
u
σ , σ tensile strengths for loading along and transverse to, respectively, the direction of preferred
up un
orientation in a transversely isotropic material
ε strain at break obtained from a tensile test at constant specimen deformation rate
u
ε , ε strains at break for loading along and transverse to, respectively, the direction of preferred
up un
orientation in a transversely isotropic material
σ tensile creep rupture strength
c
σ , σ creep rupture strengths for loading along and transverse to, respectively, the direction of preferred
cp cn
orientation in a transversely isotropic material
σ tensile fatigue strength
f
4 © ISO 2004 – All rights reserved
σ , σ tensile fatigue strengths for loading along and transverse to, respectively, the direction of preferred
fp fn
orientation in a transversely isotropic material
3.4 Material properties for processing simulation (see Tables 5 to 11)
η melt viscosity
η uniaxial extensional viscosity
eu
η biaxial extensional viscosity
eb
η viscosity of the reactive system
reactive
N first normal stress difference
ρ bulk density
B
ρ melt density
m
ρ density of the solid
s
ρ density of reacted system
reacted
k thermal conductivity
k thermal conductivity of the polymer melt
m
c specific heat
p
c specific heat of the polymer melt
pm
T solidification temperature, a reference temperature defined by the mould filling simulation software
s
T ejection temperature, a reference temperature defined by the mould filling simulation software
ej
v specific volume
∆H heat of reaction
r
t isothermal induction time
ind
α gelation conversion
gel
R reaction rate
µ , µ dynamic coefficients of friction between plastic and metal used for the barrel or screw respectively
b s
T melting temperature
m
T glass transition temperature
g
T crystallisation temperature
c
∆H enthalpy of melting
f
∆H enthalpy of crystallization
c
X degree of crystallinity
X rate of crystallization
S moulding shrinkage parallel to the direction of preferred orientation
Mp
S moulding shrinkage normal to the direction of preferred orientation
Mn
ν Poisson’s ratio for a transversely isotropic material determined with the uniaxial stress applied along
pn
the direction of preferred orientation
ν Poisson’s ratio for a transversely isotropic material determined with the applied stress along a
np
direction normal to the direction of preferred orientation and the lateral strain measured in the
preferred orientation direction
G shear modulus of a transversely isotropic material for stress application in the direction of preferred
p
orientation
α coefficient of linear thermal expansion parallel to the direction of preferred orientation in an
p
anisotropic material
α coefficient of linear thermal expansion normal to the direction of preferred orientation in an
n
anisotropic material
4 Data needed for design
4.1 General
The design data identified here are grouped under two headings:
Data for analysis of thermomechanical performance (section 4.2)
Data for processing analysis (section 4.3)
4.2 Design for thermomechanical performance
4.2.1 The design process
The process of design for the mechanical performance of a component involves two operations. The first is an
analysis of the stress and strain distributions in the component under service load. The second is a
comparison of the maximum levels of stress, strain or displacement predicted by the analysis with maximum
allowable values based on failure criteria for the material or operating conditions of the component. These
operations are then repeated in order to select component dimensions and geometry whilst ensuring that safe
limits are not exceeded. The data requirements for these two operations are different.
The data requirements for stress analysis are determined by the constitutive law that relates stress and strain
under the appropriate service loading conditions. Choice of a valid constitutive relationship will depend upon
the following factors.
Mechanical behaviour, whether the material is isotropic or anisotropic or shows glassy or rubber-like
behaviour.
The level of induced strain. If this is small, then linear viscoelastic or linear elastic behaviour may be
considered but, at higher strains, relationships between stress and strain will be non-linear.
The history of the applied load or displacement and the temperature. Since plastics are viscoelastic,
properties depend on time, frequency and strain rate and so their response to short-term loads such as
impact will be very different from that under sustained load.
6 © ISO 2004 – All rights reserved
A finite element analysis (FEA) is a versatile method for calculating stress, strain and temperature distributions
in a component of complex geometry. For this reason, the data requirements identified here for performing a
stress analysis have been guided by available materials models that are suitable for plastics. An accurate
calculation relies on the use of a materials model for the analysis which employs a realistic constitutive
relationship.
The satisfactory operating limits of a component may be specific to the component or the plastics material
from which it is made. Safe operating limits for the material are generally expressed in terms of ultimate
values of stress or strain and will depend on many factors such as the temperature, the humidity, processing
conditions, the presence of an aggressive environment and the history of the applied load. Where failure is
caused by crack growth, additional property data may be needed.
4.2.2 Design data for thermomechanical performance
Data required for design for thermomechanical performance consist of data for carrying out a stress analysis
and data for estimating material failure. In principle, these data requirements depend on the detailed materials
characteristics exhibited by the material, and on the service conditions relevant to the application. However, in
practice, the designer may adopt various simplifications by approximating materials behaviour or service
conditions in order to make the design analysis technically tractable and financially viable. This influences
data requirements and the practical use of data.
From the designer’s point of view, the simplest form of materials behaviour is that of an isotropic, linear,
temperature-insensitive, elastic material. However, as stated in section 4.2.1, plastics may exhibit aspects of
anisotropy, nonlinearly, temperature-dependence, viscoelasticity or plasticity. Where a particular aspect is
relevant to a design problem, the designer may decide to avoid a more complex analysis by assuming a
simpler form of behaviour and compensate for this by use of “effective” material properties. Examples include
use of a secant or tangent modulus to represent nonlinearity in a linear analysis, use of a long-time creep
modulus to represent viscoelasticity in an elastic analysis, and use of “average” or “representative” property
values to replace anisotropy and temperature-sensitivity. However, although a simpler (approximate) form of
representation may be used, data for the more complex form of behaviour will generally be required in order to
select appropriate “effective” properties.
Definition of the design problem involves specification of component geometry (shape, size, etc.) and service
conditions (e.g. loads and other constraints). Although FEA packages can handle complex circumstances, the
designer may idealise component geometry and may approximate service conditions in order to simplify the
design calculations (e.g. by creating a “statically determinate” situation for which stresses and strains can be
calculated separately, only the latter calculation requiring material properties). Similarly, the designer may use
an approximate design calculation (e.g. assuming “pseudo-elasticity”). These idealisations and assumptions
introduce inaccuracies into the design predictions which are not attributable to the quality of the design data,
although appropriate data selection is required.
A crucial aspect of design analysis is the selection of suitable materials models. This selection determines
consequent requirements for materials design data, and depends, in particular, on the nature of the service
loads, for example:
sustained loading, involving effects such as creep or stress relaxation, for which time under load is the
important parameter;
cyclic loading, for example in damped vibrations, for which frequency is the important parameter;
high-rate loading, for example due to impact, for which strain rate is the important parameter.
Table 1 — Typical service conditions, materials behaviour and model types
Service conditions Crucial parameter Relevant types of materials Model type(s)
behaviour (see below)
Simpler conditions Elastic A, B
—
Elastic–plastic C
Sustained loading Time Viscoelastic C1, D1, E1
or
Cyclic loading Frequency C2, D2, E2
viscoplastic
High-rate loading Strain rate C3, D3, E3
Model type:
a) Linear elasticity is the simplest and most commonly used materials model, at least for a first analysis.
b) A hypoelastic model enables approximate solutions to be obtained under strain levels where behaviour is non-
linear. Hyperelastic models are available for elastomeric materials and are not considered in this International
Standard.
c) Elastic–plastic models for metals are available in most FEA packages and are able to handle non-linear and three-
dimensional stress conditions. Those based on von Mises yielding may have restricted suitability for plastics, and a
more general form of the yield criterion with sensitivity to hydrostatic stress (the linear Drucker–Prager model) is
considered here. Some versions of elastic–plastic models combine the effects of elasticity, plasticity and also time,
frequency or rate. These latter types of model (C1, C2 and C3) are indicated in this table, but only C3 is considered
in this International Standard.
d) Linear viscoelasticity is limited to small-strain behaviour, but data can be used in the three different forms (D1, D2,
D3) depending on whether time, frequency or rate is the crucial service parameter.
e) Non-linear viscoelasticity models for general service conditions are not available in a useable form, but models
exist for use under special conditions. These include a creep form (E1) based on isochronous curves, a finite-linear
form (E2) for large amplitude vibrations and a rate-dependent form (E3): the last two are not discussed further in
this International Standard.
As already noted, the stress analysis will also need to consider isotropic or anisotropic properties, linear or
non-linear behaviour and the effects of temperature. It is therefore evident that there are many sets of
conditions under which materials properties may be needed in principle, and it is necessary to focus on the
most important cases. This is discussed now with reference to the model types indicated in Table 1.
Further consideration of these types leads to identification of the data required for design for
thermomechanical performance. These data are summarised in Table 2 for isotropic materials. Anisotropic
materials require additional data that describe the variation of properties with direction in the material. The
simplest situation arises with the loading of parts in the form of a plate or panel where stresses are confined to
a plane and stresses through the thickness direction are neglected. This is assumed in Table 3. Criteria for
determining when material rupture will take place under multiaxial stress states and arbitrary loading histories
have not been established for plastics. Ultimate values obtained from tensile tests under specific loading
histories are indicated in Table 4. The symbols used in these tables are explained in Section 3.
When material behaviour is actually isotropic linear elastic, the data shown in Table 2 for model A are all that
is required. When the behaviour is more complex, but an isotropic linear elastic analysis is performed, data
relevant to the other models may be needed in order to select appropriate “effective” properties. For example,
data for models D and E give effective properties to represent viscoelastic effects, data for models C and E
can be used to select effective properties to handle nonlinearly, and data from Table 3 can be used to select
effective properties to take account of the effects of anisotropy. When the design analysis takes these factors
into account in full, then data for models C, D and E, and from Table 3, are required in their own right (but see
Note to Table 3).
8 © ISO 2004 – All rights reserved
Table 2 — Data required for stress analysis (isotropic material)
Behaviour Model type Properties Variable(s)
Linear elastic A E, ν T
Non-linear elastic B E, ν, T
σ ε, T
e
Non-linear (elastic–plastic) C E, ν T
p
σ ε , T
T
p p
λ, ν , ψ ε , T
Linear viscoelastic D1 D, E , ν t, T
R
D2 E', E" (or G', G"), ν f, T
D3 ρ T
E, ν ε , T
Non-linear viscoelastic E1 D, ν t, σ, T
E , ν t, ε, T
R
e
Rate-dependent, elastic–plastic C3 E, ν ε , T
p
p
σ ε , ε , T
T
p
p p
λ, ν , ψ ε , ε , T
Table 3 — Data required for stress analysis (anisotropic material)
Behaviour Model TypeProperties Variables
Linear elastic A E , E , ν , G T
p n pn p
Non-linear Ep, E , ν , G T
n pn p
(Elastic–plastic)
p
C ε , σ ε , T
Tp Tn
p
σ , σ ε , T
Sp Sn
Linear D , D t, T
p n
D1
Viscoelastic
Non-linear Viscoelastic E1 D , D t, σ, T
p n
Rate-dependent, E , E , ν , G ε , T
p n pn p
Elastic–plastic
p
p
C3 σ , σ ε , ε , T
Tp Tn
p
p
σ , σ ε , γ , T
Sp Sn
NOTE The above models and data requirements for anisotropic materials are clearly
more complicated than those for isotropic materials and, except for the linear elastic case, are
likely to be used very rarely except for the purpose of selecting effective properties.
Under certain circumstances, additional property data will be required over and above those identified in
Tables 2 and 3. If the analysis involves changes in temperature during loading, then the thermal expansion
coefficient α (α and α for anisotropic materials) will be needed. If the loading generates high accelerations
p n
such that inertial forces are significant, then the density ρ of the material must be known. In situations where it
is necessary to predict the effects of internal heating of the plastic material arising from large strain and high
strain-rate loading, then data on the specific heat c will also be needed.
p
Furthermore, materials whose properties are sensitive to the concentration of absorbed water will need to
have data supplied for material that has been conditioned at the relevant humidity for the application.
Table 4 — Ultimate values for stress and strain obtained from tensile tests with different loading
histories
Service Conditions Model type Properties Variables
Isotropic Anisotropic
Simple conditions A, B, C σ , ε σ , ε , σ , T
u u up up un
Constant elongation rate ε
un
Sustained loading D1, E1 σ σ , σ t, ch, T
c cp cn
Cyclic loading D2 σ σ , σ N, R, T
f fp fn
High-rate loading C3 σ , ε σ , ε , σ , ε , T
u u up up un
ε
un
It should be noted that the failure properties of plastics are sensitive to long-term changes in the molecular or
crystalline structure of the material brought about by various ageing processes. The most notable of these are
physical ageing (relaxation of free volume), thermal ageing, brought about by exposure to elevated
temperatures, and ultraviolet degradation caused by exposure to sunlight.
4.3 Design for processing analysis
4.3.1 Processing simulation
Among the various processing methods available for fabrication of plastics into useful parts, injection
moulding is the most prevalent method in practice. As such, the CAE (computer aided engineering) tools for
simulation of the injection moulding process are more advanced in terms of the number of programs available
and their sophistication. Recently, more emphasis has been given to the development of CAE tools for
simulation of other processing methods such as extrusion, blow moulding, and thermoforming.
4.3.2 Data for simulation of injection moulding
Simulation programs for injection moulding are available from a number of sources. In general, most of these
programs provide a two-dimensional analysis incorporating temperature distribution through the third
dimension. Enhancements to allow full three-dimensional simulation have only recently been introduced. Both
of these simulation programs are rather complex in nature requiring rigorous definition of part geometry and
utilising various viscosity models to describe the flow behaviour of polymer melts, and some expertise is
required to use these programs. To overcome the need for such rigorous analysis, several simulation
programs for simple two-dimensional simulation are currently on the market.
The main objective of these methods is to simulate the part-filling and post-filling steps in order to assess and
optimize the manufacturability of the part. The three main types of analysis involved in injection moulding
simulation are
simple mould filling analysis to determine the ability to fill the mould cavity and to assess the pressure
requirements,
advanced mould filling, packing and cooling analysis, carried out to optimize the processing conditions or
to evaluate part and mould design alternatives such as number of gates, proper gate size, its location,
etc., and
shrinkage and warpage analysis to satisfy tolerances and predict dimensional stability of the
manufactured part.
The material properties needed for simple mould filling simulation are listed in Table 5.
10 © ISO 2004 – All rights reserved
Table 5 — Data needed for injection moulding simulation — Simple mould
filling analysis of thermoplastics and thermoplastic elastomers
Property Variables
η T, γ
ρ —
m
k , c —
m pm
T , T —
s ej
Depending on the software package, reference is also made to the “no flow temperature” or the “transition
temperature” in place of the solidification temperature T . The need for T also depends on the software
s ej
package. The material properties required for advanced filling, packing and cooling analysis are shown in
Tables 6 and 7. The material property requirements are essentially the same for thermoplastics and
thermoplastic elastomers. The main differences in the case of reactive materials, such as thermosets, are the
inclusion of reaction kinetics data and use of reactive polymer viscosity data in place of melt viscosity data.
Table 6 — Data needed for injection moulding simulation — Advanced
mould filling, packing and cooling analysis of thermoplastics
and thermoplastic elastomers
Property Variable(s)
η T, γ , p
v p, T, T
k, c T
p
T p, T
s
T —
ej
When relevant data are not available, the pressure dependence of viscosity and the temperature dependence
of thermal conductivity and specific heat are not included in the analysis.
Table 7 — Data needed for moulding simulation — Mould filling, packing
and cooling analysis of reactive materials including thermosets
Property Variable(s)
η T, t, γ
reactive
ρ —
reacted
k, c T
p
∆H , R T, T
r
α —
gel
The material properties required for shrinkage and warpage analysis are shown in Table 8.
Table 8 — Data needed for injection moulding simulation — Additional data for
shrinkage & warpage analysis
Property Variable(s)
S , S h, p
Mp Mn CH
X (semicrystalline materials) T
X (semicrystalline materials) T, T
E , E T
p n
ν , ν , G —
pn np p
α , α T
p n
4.3.3 Data for simulation of extrusion
The simulation of extrusion generally includes consideration of the solids transport, the melting of the polymer
in the barrel, flow of the melt in the die and the cooling of the extruded shape. Available CAE packages
employ different viscosity models to describe the flow behaviour of the polymer melt (see Annex B) and make
various simplifying assumptions. The simplifying assumptions typically relate to neglecting contributions from
extensional flow, thereby avoiding the need for data on uniaxial extensional viscosity and the first normal
stress difference.
The material properties needed for simulation of extrusion processes incorporating these analyses are listed
in Table 9.
Table 9 — Material properties needed for simulation of extrusion
Type of analysis Property Variable(s)
T , ∆H (semicrystalline materials) —
m f
T (amorphous materials) —
g
ρ , ρ —
m s
Solids transport and melting of the polymer
µ , µ p, T, v
b s s
ρ p
B
k, c T
p
ρ
m
k c T
m pm
Flow of melt in the die
η, N T, γ
η T, t, ε
eu
T , ∆H (semicrystalline materials) T
c c
Cooling of the extrudate
X T, T
In practice, the temperature dependence of k and c is often ignored if the associated loss of accuracy is
p
considered acceptable.
4.3.4 Data for simulation of blow moulding, blown film extrusion and thermoforming
Injection blow moulding and thermoforming processes involve deformation of a profile or a sheet in a softened
state, while extrusion blow moulding and blown film extrusion processes involve deformation in the melt state.
The material properties needed for these simulations are listed in Tables 10 and 11.
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Table 10 — Material properties needed for simulation of injection blow moulding and thermoforming
Type of Analysis Property Variables
Reheating the preform or sheet k, c T
p
Deformation of softened material k, c T
p
N T, γ
η T, t, ε
eb
Solidification of the formed shape T (amorphous materials) T , p
s
T , ∆H (semicrystalline materials) T
c c
X T, T
Table 11 — Material properties needed for simulation of extrusion blow moulding, and blown film
extrusion
Type of Analysis Property Variables
Melting of polymer in the barrel T , ∆H (semicrystalline materials)
m f
T (amorphous materials)
g
ρ
m
µ , µ p, T, v
b s s
ρ p
B
k, c T
p
Flow of melt in the die ρ
m
k, c T
p
η, N T, γ
η , η T, t, ε
eu eb
Cooling of the extrudate T , ∆H (semicrystalline materials) T
c c
X T, T
5 Determination of design data
5.1 General
In this section, preferred test methods are identified for determining the properties shown in Tables 2 to 11.
Standard test specimens and test conditions to be used for the acquisition of data are also recommended for
each of the properties. Section 5.2 deals with data needed for design for mechanical performance and 5.3
with data needed for processing analysis.
For those properties for which ISO standards are not available for the measurement of data, reference is
made, through the use of notes to the tables, to apparatus and specimens which have been used successfully.
These methods may be subjects for future standards development.
5.2 Data acquisition for design for mechanical performance
Table 12 shows test methods recommended for determining the mechanical property data listed in Tables 2, 3
and 4.
The methods that are based on International Standards employ standard test specimens that are prepared
under well-specified conditions. It should be noted that the material structure in these specimens will, in
general, be different from that in the component to be designed. The influence that these structural differences
will have on property values will depend upon the property, the processing method and conditions and the
geometry of the component. Procedures for increasing the relevance of test specimen data for design are not
yet recognised.
NOTE Working groups in ISO TC 61 are considering suitable mould designs for preparing additional standard test
specimens in the form of a plate by injection moulding (ISO 294-5).
By testing specimens cut from the plate along and transverse to the direction of melt flow into the mould, it
may be possible to obtain upper and lower bounds to properties arising from molecular or fibre orientation.
Selection of appropriate property values within these bounds will require knowledge of the flow conditions in
critical regions of the component.
Estimates of the anisotropy in tensile modulus of short-fibre reinforced plastics may also be obtained from flow
simulation packages that calculate fibre orientation functions throughout a moulded product. A knowledge of
fibre and matrix properties is required as well as certain other parameters. An important feature of this
approach to the characterisation of elastic behaviour is that information is generated on the variation of
properties through the thickness of the moulding. However, as with any predictive method, there will, in
general, be some uncertainty in the accuracy of derived properties or performance values.
The precision with which specific test data can be used for design will also be restricted by batch-to-batch
variations in material properties. The precision of data for design can then be increased by the statistical
analysis of data from different batches.
Despite these limitations in test specimen data, the test methods in Table 12 are highly relevant for the
acquisition of design data.
5.3 Data acquisition for design for processing
Table 13 shows recommendations for determining the data needed for processing simulations listed in Tables 5
to 11.
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