1、BRITISH STANDARDBS EN 14186:2007Advanced technical ceramics Mechanical properties of ceramic composites at room temperature Determination of elastic properties by an ultrasonic techniqueThe European Standard EN 14186:2007 has the status of a British StandardICS 81.060.30g49g50g3g38g50g51g60g44g49g42
2、g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 14186:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 Janu
3、ary 2008 BSI 2007ISBN 978 0 580 58326 1National forewordThis British Standard is the UK implementation of EN 14186:2007. It supersedes DD ENV 14186:2002 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee RPI/13, Advanced technical ceramics.A list of organ
4、izations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligatio
5、ns.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN 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 elast
6、icproperties by an ultrasonic techniqueCramiques techniques avances - Proprits mcaniquesdes cramiques composites temprature ambiante -Dtermination des proprits lastiques par une mthodeultrasonoreHochleistungskeramik - Mechanische Eigenschaftenkeramischer Verbundwerkstoffe bei Raumtemperatur -Bestimm
7、ung von elastischen Eigenschaften mittelsUltraschallwellenThis 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
8、any alteration. Up-to-date lists and bibliographical 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
9、by translationunder the responsibility of a CEN 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, Ge
10、rmany, Greece, Hungary, Iceland, Ireland, Italy, 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 NORMUNGMa
11、nagement Centre: rue de Stassart, 36 B-1050 Brussels 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) 2 Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Princi
12、ple7 5 Significance and use .10 6 Apparatus .10 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 pr
13、eparation.11 9 Test procedure.12 9.1 Choice of 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 refra
14、cted angle r.14 10.4 Identification of the elastic 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
15、.2 Criterion of validity for the reliability of 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 Bib
16、liography 24 EN 14186:2007 (E) 3 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 ide
17、ntical text or by endorsement, 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 b
18、ound to implement this European 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,
19、 Switzerland and United Kingdom. EN 14186:2007 (E) 4 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 f
20、rom the 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 kno
21、wn. 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 might not be comparable with moduli obtai
22、ned by 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 amendme
23、nts) applies. 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 laborator
24、ies (ISO/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 behaviou
25、r of a 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 com
26、ponents 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 coordin
27、ate system is chosen along the axes of symmetry, the stiffness matrix Cijand the compliance matrix Sijcan be written as follows: EN 14186:2007 (E) 5 =654321665544332313232212131211654321000000000000000000000000CCCCCCCCCCCC=654321665544332313232212131211654321000000000000000000000000SSSSSSSSSSSSNOTE
28、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 constants: =
29、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 of incidence i
30、angle between the direction 3 normal to the test specimen front face and the direction niof the incident wave (see Figure 1 and Figure 2) EN 14186:2007 (E) 6 3.4 refracted angle iangle between the direction 3 normal to the test specimen front face and the direction n of propagation of the wave insid
31、e 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 the material (see Figure 1) Figure
32、1 Definition of the angles Figure 2 Propagation in the plane of incidence EN 14186:2007 (E) 7 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) (see Figure 1 and Figure 2): n1= sinrsin n2= sinrco
33、s 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 flight time of the wave when the test specimen is in
34、 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 bulk density bbulk density of the specimen 4 Principle T
35、he 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 flui
36、d (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. EN 14186:
37、2007 (E) 8 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 within the material in one, two or three bulk waves (one quasi longitudinal wa
38、ve 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 each of these waves. The difference in propagation time of each of the wave
39、s 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-transverse waves, and is only valid when the QL and the QT waves are app
40、ropriately separated (see Figure 4). EN 14186:2007 (E) 9 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) Temporal waveform of the overlapping QL and QT waves at an incidence angle iFigure 4 Overlappi
41、ng 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 the wave propagation equations. Youngs moduli, shear moduli and Poisson coefficients are deter
42、mined from these components. EN 14186:2007 (E) 10 5 Significance and use Only two constants (Lams coefficients or Youngs 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 ma
43、terials, 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 evaluatio
44、n 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 meas
45、urement 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 methods, the determination of elastic properties by the ultrasonic method described here is not based on the evaluatio
46、n 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 velocities. Therefore the values of Youngs moduli, shear moduli and Poisson ratios determined by the two methods mi
47、ght 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, whereas the ultrasonic method assumes adiabatic conditions. In addition to the ultrasonic
48、method described here, there also exist other non destructive methods to determine the elastic properties, for instance the resonant beam technique and the impulse excitation method. Each of these has its relative merits and disadvantages. The selection of a particular non destructive method shall b
49、e considered on a case-by-case basis. 6 Apparatus 6.1 Ultrasonic tank with thermostatic control The ultrasonic tank shall be capable of maintaining the temperature of the coupling fluid constant to within 0,1 C for the full duration of the test. NOTE This requirement is imposed because the wave propagation velocity in the coup
