DIN EN 14186-2008 Advanced technical ceramics - Mechanical properties of ceramic composites at room temperature - Determination of elastic properties by an ultrasonic technique Eng.pdf

1、February 2008DEUTSCHE NORM English price group 13No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 81.060.30!$LCN“141324

2、3www.din.deDDIN EN 14186Advanced technical ceramics Mechanical properties of ceramic composites at room temperature Determination of elastic properties by an ultrasonic techniqueEnglish version of DIN EN 14186:2008-02Hochleistungskeramik Mechanische Eigenschaften keramischer Verbundwerkstoffe bei Ra

3、umtemperatur Bestimmung von elastischen Eigenschaften mittels UltraschallwellenEnglische Fassung DIN EN 14186:2008-02SupersedesDIN V ENV 14186:2002-11www.beuth.deDocument comprises 27 pagesDIN EN 14186:2008-02 2 National foreword This standard has been prepared by Technical Committee CEN/TC 184 “Adv

4、anced technical ceramics” (Secretariat: BSI, United Kingdom). At present a DIN committee does not exist for this standard since the parties concerned have not shown any interest in work on the subject. The Normenausschuss Materialprfung (Materials Testing Standards Committee) is obliged to publish t

5、he standard, however, as the subject falls in its domain. The DIN Standard corresponding to the International Standard referred to in clause 2 of the EN is as follows: ISO 3611 DIN 863-1 Amendments This standard differs from DIN V ENV 14186:2002-11 as follows: a) The prestandard status has been chan

6、ged to that of a full standard. b) Clause 3 “Terms and definitions” has been revised. c) The standard has been editorially revised. Previous editions DIN V ENV 14186: 2002-11 National Annex NA (informative) Bibliography DIN 863-1, Micrometers Standard design external micrometers Concepts, requiremen

7、ts and testing EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 14186November 2007ICS 81.060.30 Supersedes ENV 14186:2002 English VersionAdvanced technical ceramics - Mechanical properties of ceramiccomposites at room temperature - Determination of elasticproperties by an ultrasonic techniqueCramiq

8、ues techniques avances - Proprits mcaniquesdes cramiques composites temprature ambiante -Dtermination des proprits lastiques par une mthodeultrasonoreHochleistungskeramik - Mechanische Eigenschaftenkeramischer Verbundwerkstoffe bei Raumtemperatur -Bestimmung von elastischen Eigenschaften mittelsUltr

9、aschallwellenThis European Standard was approved by CEN on 13 October 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliogr

10、aphical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a C

11、EN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Ita

12、ly, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 B

13、russels 2007 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14186:2007: EEN 14186:2007 (E) Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle7 5 Significance and use .10 6 Apparatus .10

14、 6.1 Ultrasonic tank with thermostatic control.10 6.2 Temperature measurement device 10 6.3 Test specimen holder10 6.4 Transducers .11 6.5 Transducer holders .11 6.6 Pulse generator11 6.7 Signal recording system .11 7 Test specimens11 8 Test specimen preparation.11 9 Test procedure.12 9.1 Choice of

15、frequency 12 9.2 Establishment of the test temperature 12 9.3 Reference test without test specimen .12 9.4 Measurement with the specimen .13 10 Calculation14 10.1 Delay .14 10.2 Calculation of the propagation velocities .14 10.3 Calculation of the refracted angle r.14 10.4 Identification of the elas

16、tic constants, Cij.14 10.5 Back calculation of the phase velocities.18 10.6 Polar plots of the velocity curves 18 10.7 Calculation of the quadratic deviation.18 10.8 Calculation of the engineering constants .18 11 Test validity 19 11.1 Measurements19 11.2 Criterion of validity for the reliability of

17、 the Cijcomponents19 12 Test report 19 Annex A (informative) Example of a presentation of the results for a material with orthothropic symmetry 21 A.1 Velocity curves.21 A.2 Stiffness matrix with stiffness components .22 A.3 Engineering constants 23 Bibliography 24 DIN EN 14186:2008-02 2EN 14186:200

18、7 (E) Foreword This document (EN 14186:2007) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorseme

19、nt, at the latest by May 2008, and conflicting national standards shall be withdrawn at the latest by May 2008. This document supersedes ENV 14186:2002. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this Euro

20、pean Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kin

21、gdom. DIN EN 14186:2008-02 3EN 14186:2007 (E) 1 Scope This European Standard specifies an ultrasonic method to determine the components of the elasticity tensor of ceramic matrix composite materials at room temperature. Youngs moduli, shear moduli and Poisson coefficients, can be determined from the

22、 components of the elasticity tensor. This European 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. Thi

23、s 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 might not be comparable with moduli obtained by

24、EN 658-1, EN 658-2 and EN 12289. 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) ap

25、plies. EN 1389, Advanced technical ceramics Ceramic composites Physical properties Determination of density and apparent porosity CEN/TR 13233:2007, Advanced technical ceramics Notations and symbols EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (IS

26、O/IEC 17025:2005) ISO 3611, Micrometer callipers for external measurements 3 Terms and definitions For the purposes of this document, the terms and definitions given in CEN/TR 13233:2007 and the following apply. 3.1 stress-strain relations for orthotropic material elastic anisotropic behaviour of a

27、solid homogeneous body described by the elasticity tensor of fourth order Cijkl, represented in the contracted notation by a symmetrical square matrix (6 6) NOTE 1 If the material has at least orthotropic symmetry, its elastic behaviour is fully characterised by nine independent stiffness components

28、 Cij, of the stiffness matrix (Cij), which relates stresses to strains, or equivalently by nine independent compliance components Sijof the compliance matrix (Sij), which relates strains to stresses. The stiffness and compliance matrices are the inverse of each other. If the reference coordinate sys

29、tem is chosen along the axes of symmetry, the stiffness matrix Cijand the compliance matrix Sijcan be written as follows: DIN EN 14186:2008-02 4EN 14186:2007 (E) =654321665544332313232212131211654321000000000000000000000000CCCCCCCCCCCC=654321665544332313232212131211654321000000000000000000000000SSSS

30、SSSSSSSSNOTE 2 For symmetries of higher level than the orthotropic symmetry, the Cijand Sijmatrices have the 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

31、 constants: =1213332223111333322211123331222111100000001000000100010001GGEEvEvEvEEvEvEvESijwhere E11, E22and E33are the elastic moduli in directions 1, 2 and 3 respectively; G12, G13and G23are the shear moduli in the corresponding planes; 12, 13, 23are the respective Poisson coefficients 3.3 angle o

32、f incidence iangle between the direction 3 normal to the test specimen front face and the direction niof the incident wave (see Figure 1 and Figure 2) DIN EN 14186:2008-02 5EN 14186:2007 (E) 3.4 refracted angle iangle between the direction 3 normal to the test specimen front face and the direction n

33、 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, ni) and plane (2, 3) where nicorresponds to the vector oriented along the incident plane wave and direction 2 corresponds to one of the axes of symmetry of th

34、e material (see Figure 1) Figure 1 Definition of the angles Figure 2 Propagation in the plane of incidence DIN EN 14186:2008-02 6EN 14186:2007 (E) 3.6 unit vector n unit vector oriented along the propagation direction of the incident plane wave inside the specimen, with its components nk(k = 1, 2, 3

35、) (see Figure 1 and Figure 2): n1= sinrsin n2= sinrcos n3= cosr3.7 propagation velocity V(n) phase velocity of a plane wave inside the specimen in dependence on unit vector n (i.e. in dependence on and i) NOTE Vois the propagation velocity in the coupling fluid. 3.8 delay t(n) difference between the

36、 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 3.9 thickness of the test specimen h thickness of the test specimen 3.10 bul

37、k density bbulk density of the specimen 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 parall

38、el 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 o

39、f each wave in the specimen are calculated. DIN EN 14186:2008-02 7EN 14186:2007 (E) 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 pulse sent by the emitter E is refracted withi

40、n the material in one, two or three bulk waves (one quasi longitudinal wave QL, one quasi transverse wave QT, or two quasi transverse waves QT1, QT2) that propagate in the solid at different velocities and in different directions. The receiver R collects one, two or three pulses, corresponding to ea

41、ch 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 quasi-longitudinal and one or both quasi

42、-transverse waves, and is only valid when the QL and the QT waves are appropriately separated (see Figure 4). DIN EN 14186:2008-02 8EN 14186:2007 (E) Key 1 amplitude 2 incidence angle Figure 4a) Amplitude of the QL and QT waves as a function of the incidence angle Key 1 amplitude 2 time Figure 4b) T

43、emporal waveform of the overlapping QL and QT waves at an incidence angle iFigure 4 Overlapping of QL and QT waves at an incidence angle iFrom the propagation velocities the components of the elasticity tensor are obtained through a least square regression analysis which minimises the residuals of t

44、he wave propagation equations. Youngs moduli, shear moduli and Poisson coefficients are determined from these components. DIN EN 14186:2008-02 9EN 14186:2007 (E) 5 Significance and use Only two constants (Lams coefficients or Youngs modulus and Poisson coefficient) are sufficient in order to fully d

45、escribe 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

46、 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 app

47、ropriate 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. Contrary to mechanical test method

48、s, the determination of elastic properties by the ultrasonic method described here is not based on the evaluation of the stress-strain response over a given deformation range obtained under quasi-static loading conditions, but is based on a non-destructive dynamic measurement of wave propagation vel

49、ocities. Therefore the values of Youngs moduli, shear moduli and Poisson ratios determined by the two methods might not be comparable, particularly for ceramic matrix composites that exhibit non linear stress-strain behaviour. NOTE Mechanical test methods are based on a measurement performed under isothermal conditions, wh