1、BRITISH STANDARDBS EN 15335:2007Advanced technical ceramics Ceramic composites Determination of elastic properties by resonant beam method up to 2 000 CThe European Standard EN 15335:2007 has the status of a British StandardICS 81.060.30g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44
2、g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 15335:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2007 BSI 2007ISBN 978 0 580 55779
3、 8National forewordThis British Standard is the UK 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
4、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 obligations.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARD NORME EURO
5、PENNE 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 techniques avances - Cramiques composites - Dtermination des proprits lastiques par une mthode
6、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 was approved by CEN on 26 April 2007. CEN members are bound to comply with the CEN/CENELEC I
7、nternal 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 national standards may be obtained on application to the CEN Management Centre or to any CEN
8、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 and notified to the CEN Management Centre has the same status as the official versions. CEN m
9、embers are the national standards bodies of 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, Swede
10、n, 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 rights of exploitation in any form and by any means reserved worldwide for CEN national Members.
11、 Ref. No. EN 15335:2007: EEN 15335:2007 (E) 2 Contents Page Foreword3 1 Scope 4 2 Normative references 4 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
12、 units 7 6.6 Balance .7 6.7 Micrometer8 6.8 Callipers8 7 Test specimens8 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 Measureme
13、nt at high temperatures.10 9 Calculation of results 11 9.1 Basic concept.11 9.2 How to calculate eigenfrequencies11 9.3 Identification, matching and fitting16 9.4 The two evaluation steps 18 10 Accuracy of method and errors .19 11 Test report 20 Annex A (informative) Example .21 A.1 General21 A.2 Me
14、asurement23 A.3 First evaluation step24 A.4 Second evaluation step.26 A.5 Results 26 Bibliography 28 EN 15335:2007 (E) 3 Foreword This document (EN 15335:2007) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI. This European St
15、andard 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. According to the CEN/CENELEC Internal Regulations, the national
16、 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, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Pola
17、nd, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 15335:2007 (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
18、 vacuum or inert atmosphere. The Youngs moduli and the shear moduli for different orientations with 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
19、), and tridirectional (xD, with 2 x 3) which have at least orthothropic symmetry. NOTE 1 Dynamic means 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
20、 be compared with moduli obtained in an isothermal condition by stressing statically or quasistatically 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 d
21、ocument. 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. EN 60584-1, Therm
22、ocouples Part 1: Reference tables (IEC 60584-1:1995) EN 60584-2, Thermocouples Part 2: Tolerances (IEC 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 m
23、m ISO 3611, Micrometer callipers for external measurement 3 Terms and definitions For the purposes of 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 s
24、tress required in a material to produce unit angular distortion 3.3 Poissons ratio, ratio of transverse strain to the corresponding axial strain NOTE E11, E22and E33are the elastic moduli in directions 1, 2 and 3 respectively, G12, G13and G23are the shear moduli in the corresponding planes and 12, 1
25、3, 23are the respective Poisson ratios. 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 to bending vibrations. The mechanical excit
26、ation 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 and transforms them into electrical signals.
27、 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 (fundamental vibration and harmonics up to the si
28、xth 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 achieved. NOTE When anisotropy, a specific
29、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 to determine the elasticity tensor for com
30、posites 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 moduli in standardisation for example: EN
31、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 on the Euler-Bernoulli relation, valid for
32、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 torsional vibrations. The method specified in t
33、his 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 Timoshenkos equation, taking into account for she
34、ar, 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 perpendicular to each other. The Youngs modulus is th
35、e 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 which direction, with respect to the crysta
36、llographic 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 Youngs moduli E11, E22, E33and the shear modul
37、i G12, G23, G13can 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 modulus E11, the interlaminar shear modulus G
38、13and the intralaminar shear modulus G12. Additionally for such a plate the modulus E22could be determined from a specimen cut out in direction 2, but neither E33in the direction of the thickness of the plate, nor the shear modulus G23. Contrary to mechanical test methods, the determination of elast
39、ic 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 from vibrations at very small amplitudes. Therefo
40、re the values of Youngs modulus, shear modulus and Poisson EN 15335:2007 (E) 6 ratio determined by the two types of 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 v
41、acuum chamber the prismatic test specimen is suspended by loops of carbon fibre bundles (a few hundred fibres each) 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
42、 room temperature). The characteristic spectrum of bending vibrations is registered via the other loop at the temperatures 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 analy
43、ser i transducer in a water-cooled housing: the Receiver c temperature control j insulating felt d pyrometer k prismatic 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 freque
44、ncy spectrum is transmitted by carbon fibre-bundle loops attached to transducers in water-cooled housings (right), 1, 2. Figure 1 Schematic of the resonant beam method apparatus EN 15335:2007 (E) 7 6.2 Transducers The transducers shall introduce sinusoidal vibrations of a certain range of frequencie
45、s (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 are necessary to perform t
46、he 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 spectru
47、m 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 diameter 3, inner diameter 1,5 mm, ending in a metric thread, M 2,5 should be used). The tubes with the glued in bundles are screwed into a cylindrical foot,
48、which is directly glued to the transducers (piezo-ceramics). The transducers are enclosed in water cooled housing, the cylindrical foot with the screwed in tubes and the glued in bundles are protruding into the vacuum vessel. The carbon fibre-bundles shall be as long as to centre the prismatic test
49、specimen into the hot zone of the heating element. 6.4 Pumping unit To prevent perturbation and because of the presence of carbon or carbon/carbon heating elements, carbon fibre insulating felts and the carbon fibre-bundle loops for the suspension of the test specimen, a vacuum of 3 x 10-2 Pa or inert atmosphere (Argon) is required. A suitable pumping unit and a unit for refilling with inert gas should be installed. 6.5 Control and evaluation units 6.5.1 Frequency sweeping unit A frequency sweeping unit to introduce the sinusoidal vi
