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1、BRITISH STANDARD BS EN 15335:2007 Advanced technical ceramics Ceramic composites Determination of elastic properties by resonant beam method up to 2 000 C The European Standard EN 15335:2007 has the status of a British Standard ICS 81.060.30 ? Licensed Copy: London South Bank University, London Sout
2、h Bank University, Wed Aug 08 04:05:55 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS EN 15335:2007 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2007 BSI 2007 ISBN 978 0 580 55779 8 National foreword This British Standard is the UK
3、implementation of EN 15335:2007. The UK participation in its preparation was entrusted to Technical Committee RPI/13, Advanced technical ceramics. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the n
4、ecessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University,
5、 Wed Aug 08 04:05:55 GMT+00:00 2007, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 15335 May 2007 ICS 81.060.30 English Version Advanced technical ceramics - Ceramic composites - Determination of elastic properties by resonant beam method up to 2 000 C Cramiques tec
6、hniques avances - Cramiques composites - Dtermination des proprits lastiques par une mthode de rsonance sur poutres, jusqu 2 000 C Hochleistungskeramik - Keramische Verbundwerkstoffe - Bestimmung der elastischen Eigenschaften bei Verwendung des Resonanz-Verfahrens bis 2 000 C This European Standard
7、was approved by CEN on 26 April 2007. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such n
8、ational standards 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 translation under the responsibility of a CEN member into its own language a
9、nd notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembo
10、urg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2007 CEN All righ
11、ts of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 15335:2007: E Licensed Copy: London South Bank University, London South Bank University, Wed Aug 08 04:05:55 GMT+00:00 2007, Uncontrolled Copy, (c) BSI EN 15335:2007 (E) 2 Contents Page Foreword3
12、 1 Scope 4 2 Normative references4 3 Terms and definitions .4 4 Principle5 5 Significance and use.5 6 Apparatus .6 6.1 Vacuum vessel.6 6.2 Transducers .7 6.3 Carbon fibre-bundle loops7 6.4 Pumping unit7 6.5 Control and evaluation units7 6.6 Balance .7 6.7 Micrometer8 6.8 Callipers8 7 Test specimens8
13、 7.1 General8 7.2 Shape and dimensions9 7.3 Plane parallelism9 7.4 Number of test specimens9 8 Test procedure.9 8.1 Test specimen preparation.9 8.2 Adjustment of the apparatus9 8.3 Measurement at room temperature10 8.4 Measurement at high temperatures.10 9 Calculation of results 11 9.1 Basic concept
14、.11 9.2 How to calculate eigenfrequencies11 9.3 Identification, matching and fitting16 9.4 The two evaluation steps18 10 Accuracy of method and errors .19 11 Test report20 Annex A (informative) Example .21 A.1 General21 A.2 Measurement23 A.3 First evaluation step24 A.4 Second evaluation step.26 A.5
15、Results26 Bibliography28 Licensed Copy: London South Bank University, London South Bank University, Wed Aug 08 04:05:55 GMT+00:00 2007, Uncontrolled Copy, (c) BSI EN 15335:2007 (E) 3 Foreword This document (EN 15335:2007) has been prepared by Technical Committee CEN/TC 184 “Advanced technical cerami
16、cs”, 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 endorsement, at the latest by November 2007, and conflicting national standards shall be withdrawn at the latest by November 2007. A
17、ccording to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, L
18、atvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Licensed Copy: London South Bank University, London South Bank University, Wed Aug 08 04:05:55 GMT+00:00 2007, Uncontrolled Copy, (c) BSI EN 15335:2
19、007 (E) 4 1 Scope This European Standard specifies the resonant beam method for the determination of the dynamic elastic moduli of fibre reinforced ceramic matrix composites from 20 C up to 2 000 C in vacuum or inert atmosphere. The Youngs moduli and the shear moduli for different orientations with
20、respect to the main axes of symmetry of the composite can be obtained. This document applies to ceramic matrix composites with fibre reinforcement: short fibres, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 x 3) which have at least orthothropic symmetry. NOTE 1 Dynamic mea
21、ns that the elastic moduli are determined non-quasistatically, i.e. under adiabatic conditions, as with the ultrasonic method set out in ENV 14186. The elastic moduli determined by this method may not be compared with moduli obtained in an isothermal condition by stressing statically or quasistatica
22、lly as with EN 658-1, EN 658-2, EN 1892, EN 1893, EN 12290 and EN 12291. NOTE 2 The ceramic matrix composites with fibre reinforcement, listed above, are denoted as “composites” in the course of the document. 2 Normative references The following referenced documents are indispensable for the applica
23、tion 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 60584-1, Thermocouples Part 1: Reference tables (IEC 60584-1:1995) EN 60584-2, Thermocouples Part 2: Tolerances (I
24、EC 60584- 2:1982 + A1:1989) EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:2005) ISO 3599, Vernier callipers reading to 0,1 and 0,05 mm ISO 3611, Micrometer callipers for external measurement 3 Terms and definitions For the purposes o
25、f this document, the following terms and definitions apply. 3.1 Youngs modulus, E stress required in a material to produce unit strain in uniaxial extension or compression 3.2 shear modulus, G shear stress required in a material to produce unit angular distortion 3.3 Poissons ratio, ratio of transve
26、rse strain to the corresponding axial strain NOTE E11, E22 and E33 are the elastic moduli in directions 1, 2 and 3 respectively, G12, G13 and G23 are the shear moduli in the corresponding planes and 12, 13, 23 are the respective Poisson ratios. Licensed Copy: London South Bank University, London Sou
27、th Bank University, Wed Aug 08 04:05:55 GMT+00:00 2007, Uncontrolled Copy, (c) BSI EN 15335:2007 (E) 5 4 Principle The test specimen, a long thin prismatic beam (ratio of length to width or length to height bigger than 10), cut from the composite along a specific orientation of interest, is excited
28、to bending vibrations. The mechanical excitation at continuously variable frequencies is provided by means of a transducer that transforms cyclic electrical signals to cyclic mechanical forces on the test specimen. A second transducer senses the resulting mechanical vibrations of the test specimen a
29、nd transforms them into electrical signals. The resulting spectrum (amplitude as function of frequency) up to frequencies enclosing the sixth mode of vibrations of the test specimen, is registered and stored in a spectrum analyser. From the resonant frequencies, i.e. the peaks of the spectrum (funda
30、mental vibration and harmonics up to the sixth mode), the dimensions and the density of the test specimen, the elastic moduli can be calculated by numerically solving Timoshenkos equation. For one test specimen the Youngs modulus and two shear moduli in directions perpendicular to each other can be
31、achieved. NOTE When anisotropy, a specific feature of composites, is taken into account, the elastic behaviour can be fully characterised only by the elasticity tensor with a certain number of independent coefficients, this number depending on the crystallographic symmetry of the composite (a method
32、 to determine the elasticity tensor for composites is given in ENV 14186). From these coefficients the elastic moduli (Youngs moduli, shear moduli and Poisson ratios) can be calculated. 5 Significance and use The resonant beam method is frequently applied for the determination of the dynamic elastic
33、 moduli in standardisation for example: EN 843-2, CEN/TS 820-5, ISO 17561, ASTM C848-88, ASTM C623-92(2005). For all these applications, it is common that the influence of shear, which is the bigger, the higher and the mode of vibration, is ruled out. For the calculation of results a formula basing
34、on the Euler-Bernoulli relation, valid for the fundamental mode only, is applied and is combined with correction factors for higher modes (in general only the first mode, i.e. the first overtone is considered additionally to the fundamental mode). The shear moduli are determined separately from tors
35、ional vibrations. The method specified in this document turns the problem around. The higher modes are taken into account (up to the sixth mode) and thus shear deformation is provoked for the determination of the shear moduli with bending vibrations. In this document an equation, derived from Timosh
36、enkos equation, taking into account for shear, is applied for the calculation of the moduli. With the resonant beam method specified in this document, the elastic moduli are determined in principle for one test specimen. One Youngs modulus and two shear moduli are determined in directions perpendicu
37、lar to each other. The Youngs modulus is the longitudinal modulus in the length direction of the prismatic test specimen, while the shear moduli are the moduli along the width and thickness of the test specimen (Poisson ratios can be calculated from these moduli). Thus it is important to observe in
38、which direction, with respect to the crystallographic symmetry, the prismatic test specimen is cut from the composite. For example, from a 2,5 D- or a 3 D-composite (orthothropic symmetry) test specimens can be cut out perpendicular to each other in reinforcing directions 1, 2 and 3, so that the You
39、ngs moduli E11, E22, E33 and the shear moduli G12, G23, G13 can be determined. For a plate of a 2D-composite (quadratic or tetragonal symmetry), with a test specimen cut out in the direction of the fibre reinforcement, direction 1, the technique specified in this document generates the longitudinal
40、modulus E11, the interlaminar shear modulus G13 and the intralaminar shear modulus G12. Additionally for such a plate the modulus E22 could be determined from a specimen cut out in direction 2, but neither E33 in the direction of the thickness of the plate, nor the shear modulus G23. Contrary to mec
41、hanical test methods, the determination of elastic properties by the resonant beam method specified 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 f
42、rom vibrations at very small amplitudes. Therefore the values of Youngs modulus, shear modulus and Poisson Licensed Copy: London South Bank University, London South Bank University, Wed Aug 08 04:05:55 GMT+00:00 2007, Uncontrolled Copy, (c) BSI EN 15335:2007 (E) 6 ratio determined by the two types o
43、f methods just mentioned may not be comparable, particularly for ceramic matrix composites, which may exhibit non linear stress-strain behaviour. 6 Apparatus 6.1 Vacuum vessel Inside a vacuum chamber the prismatic test specimen is suspended by loops of carbon fibre bundles (a few hundred fibres each
44、) and excited to bending vibrations via one of these loops. The test specimen hangs into a heating element (optionally this should be partly removable when adjusting the test specimen at room temperature). The characteristic spectrum of bending vibrations is registered via the other loop at the temp
45、eratures of interest. See an example of a vacuum vessel illustrated in Figure 1. Key a control and evaluation unit h transducer in a water-cooled housing: the Transmitter b network analyser i transducer in a water-cooled housing: the Receiver c temperature control j insulating felt d pyrometer k pri
46、smatic test specimen e thermocouple l heating element f vacuum vessel m carbon fibre loops g pumping unit NOTE The prismatic test specimen is excited to bending vibrations and the frequency spectrum is transmitted by carbon fibre-bundle loops attached to transducers in water-cooled housings (right),
47、 1, 2. Figure 1 Schematic of the resonant beam method apparatus Licensed Copy: London South Bank University, London South Bank University, Wed Aug 08 04:05:55 GMT+00:00 2007, Uncontrolled Copy, (c) BSI EN 15335:2007 (E) 7 6.2 Transducers The transducers shall introduce sinusoidal vibrations of a cer
48、tain range of frequencies (generated by a frequency synthesiser) to one end of the test specimen and collect the resonant spectrum of the test specimen on the other end. The transducers shall have a flat response curve (i.e. no resonances of its own). Both, sinusoidal vibrations and flat response ar
49、e necessary to perform the method. Piezo-ceramics (piezoelectric effect), with a range of operation 1 kHz to 200 kHz and a signal to noise ratio 20 dB, should be used. 6.3 Carbon fibre-bundle loops Loops of carbon fibre-bundles with a few hundred fibres in the bundle to transmit and receive introduce and accept the spectrum of vibrations. The ends of each of the bundles are fixed by a polymeric glue into a short tube (the tube should be made of aluminium, outer