1、 Reference number ISO 20506:2005(E) ISO 2005INTERNATIONAL STANDARD ISO 20506 First edition 2005-10-01 Fine ceramics (advanced ceramics, advanced technical ceramics) Determination of the in-plane shear strength of continuous-fibre-reinforced composites at ambient temperature by the Iosipescu test Cra
2、miques techniques Dtermination de la rsistance au cisaillement plan des composites renforcs de fibres continues temprature ambiante par lessai de Iosipescu ISO 20506:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be prin
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7、ail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2005 All rights reservedISO 20506:2005(E) ISO 2005 All rights reserved iii Contents Page Foreword iv 1 Scope. 1 2 Normative references. 1 3 Terms and definitions. 1 4 Symbols and designations 2 5 Principle. 3 6 Interferences. 4 6.1
8、 Test environment 4 6.2 Preparation of test pieces 4 6.3 Failures outside gauge section . 4 6.4 Clamping forces 4 6.5 Friction. 4 6.6 Thin test pieces. 4 7 Apparatus 4 7.1 Testing machines 4 7.2 Data acquisition 5 7.3 Dimension-measuring devices 5 7.4 Test fixture. 5 8 Test piece 6 8.1 Test piece ge
9、ometry. 6 8.2 Test piece preparation 6 8.2.1 Customary practices 6 8.2.2 Standard procedures 7 8.2.3 Handling precautions . 7 8.3 Number of test pieces 7 9 Precautionary statement 7 10 Test conditions . 7 10.1 Test modes and rates. 7 10.1.1 Displacement rate. 7 10.1.2 Load rate 8 11 Procedure 8 11.1
10、 Test piece dimensions . 8 11.2 Preparations for testing . 8 11.3 Conducting the test 8 11.3.1 Mount the test piece in the test fixture. 8 11.3.2 Begin data acquisition 9 11.3.3. Initiate the action of the test machine . 9 11.4 Completion of testing. 9 11.5 Post test. 11 12 Calculation of results .
11、11 12.1 Shear strength. 11 12.2 Statistics 11 13 Test report. 12 Annex A (informative) Results of round-robin tests. 13 Bibliography . 15 ISO 20506:2005(E) iv ISO 2005 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards
12、 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 organiza
13、tions, 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 t
14、he 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
15、 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 20506 was prepared by Technical Committee ISO/TC 206, Fine cer
16、amics. INTERNATIONAL STANDARD ISO 20506:2005(E) ISO 2005 All rights reserved 1 Fine ceramics (advanced ceramics, advanced technical ceramics) Determination of the in-plane shear strength of continuous-fibre-reinforced composites at ambient temperature by the Iosipescu test 1 Scope This International
17、 Standard specifies a method for the determination of in-plane shear strength of continuous- fibre-reinforced ceramic composites at ambient temperature by the Iosipescu test. Methods for test piece fabrication, testing modes and rates (load rate or displacement rate), data collection, and reporting
18、procedures are addressed. This International Standard applies primarily to advanced ceramic or glass-matrix composites with continuous- fibre reinforcement having uni-directional (1-D), bi-directional (2-D) or 3-D fibre architecture. This test method does not address composites with discontinuous-fi
19、bre-reinforced, whisker-reinforced or particulate-reinforced ceramics. NOTE 1 Values expressed in this International Standard are in accordance with the International System of Units (SI). NOTE 2 This International Standard is based on ASTM C1292. 2 Normative references The following referenced docu
20、ments 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 3611, Micrometer callipers for external measurement ISO 7500-1, Metallic m
21、aterials Verification of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and calibration of the force-measuring system ASTM C1292, Standard Test Method for Shear Strength of Continuous Fiber-Reinforced Advanced Ceramics at Ambient Temperatures 3 Terms and d
22、efinitions For the purposes of this document, the following terms and definitions apply: 3.1 fine ceramic (advanced ceramic, advanced technical ceramic) highly engineered, high-performance predominately non-metallic, inorganic, ceramic material having specific functional attributes ISO 20506:2005(E)
23、 2 ISO 2005 All rights reserved3.2 continuous-fibre-reinforced ceramic composite CFCC ceramic matrix composite in which the reinforcing phase consists of a continuous fibre, continuous yarn, or a woven fabric 3.3 shear failure load maximum load required to fracture a shear-loaded test piece 3.4 shea
24、r strength maximum shear stress which a material is capable of sustaining NOTE Shear strength is calculated from the shear-fracture load and the shear-loaded area. 4 Symbols and designations Symbols used throughout this International Standard and their designations are given in Table 1. Table 1 Symb
25、ols and designations Symbol Designation Unit References L Test piece length mm Table 2 h Distance between notches mm Table 2 Equation 2 w Test piece width mm Table 2 t Test piece thickness mm Table 2 Equation 2 R Notch radius mm Table 2 Notch angle Table 2 n Number of valid tests 1 Equations 3, 4 P
26、maxMaximum load N Equation 1 A Shear area of test piece mm 2Equation 1 IPIn-plane shear strength MPa Equation 1 X mean MPa Equation 3, 4, 5 SD standard deviation MPa Equation 4 CV Coefficient of variation 1 Equation 5 ISO 20506:2005(E) ISO 2005 All rights reserved 3 5 Principle This International St
27、andard is for material development, material comparison, quality assurance, characterization, reliability and design data generation. The in-plane shear strength of continuous-fibre- reinforced ceramic composites, as determined by this International Standard, is measured by the Iosipescu test. Accor
28、ding to this test, the shear strength is determined by loading a test coupon in the form of a rectangular flat strip with symmetric, centrally located V-notches using a mechanical testing machine and a modified asymmetric four-point bending fixture. Failure of the test piece occurs by shear between
29、the V-notches. Schematics of the test setup and the test piece are shown in Figures 1 and 2. Figure 1 Schematic of Iosipescu test piece subjected to asymmetric four-point bending Dimensions in millimetres Figure 2 Geometry and dimensions of Iosipescu test piece ISO 20506:2005(E) 4 ISO 2005 All right
30、s reserved6 Interferences 6.1 Test environment The test environment may have an influence on the measured shear strength. In particular, the behaviour of materials susceptible to slow-crack-growth fracture will be strongly influenced by the test environment and testing rate. Testing to evaluate the
31、maximum strength potential of a material shall be conducted in inert environments and/or at sufficiently rapid testing rates, so as to minimize slow-crack-growth effects. Conversely, testing can be conducted in environments and testing modes and rates representative of service conditions to evaluate
32、 material performance under those conditions. When testing is conducted in uncontrolled ambient air with the objective of evaluating maximum strength potential, relative humidity and temperature shall be monitored and reported. 6.2 Preparation of test pieces Preparation of test pieces, although norm
33、ally not considered a major concern with continuous-fibre-reinforced ceramic composites, can introduce fabrication flaws which may have pronounced effects on the mechanical properties and behaviour (e.g. shape and level of the resulting load-displacement curve and shear strength). Machining damage i
34、ntroduced during test piece preparation can be either a random interfering factor in the determination of shear strength of pristine material, or an inherent part of the strength characteristics to be measured. Universal or standardized test methods of surface preparation do not exist. Final machini
35、ng steps may, or may not, negate machining damage introduced during the initial machining. Thus, the history of the test piece fabrication may play an important role in the measured strength distributions and shall be reported. 6.3 Failures outside gauge section Fractures that initiate outside the u
36、niformly stressed gauge section of a test piece may be due to extraneous stresses introduced by improper loading configurations, or strength-limiting features in the microstructure of the test piece. Such non-gauge section fractures will constitute invalid tests. 6.4 Clamping forces Excessive clampi
37、ng force will induce undesirable pre-loading and may damage some materials. 6.5 Friction Most fixtures for the Iosipescu test incorporate an alignment mechanism in the form of a guide rod and a linear roller bearing. Excessive free play or excessive friction in this mechanism may introduce spurious
38、moments that will alter the ideal loading conditions. 6.6 Thin test pieces Thin test pieces (width to thickness ratio of more than 10) may suffer from splitting and instabilities rendering, in turn, invalid test results. 7 Apparatus 7.1 Testing machines The testing machine shall be verified in accor
39、dance with ISO 7500-1 and shall be at least grade 1,0. ISO 20506:2005(E) ISO 2005 All rights reserved 5 7.2 Data acquisition Obtain at least an autographic record of applied load and cross-head displacement versus time using either analogue chart recorders or digital data acquisition systems. Record
40、ing devices shall be accurate to within 1 % of the selected range for the testing equipment including readout unit, and have a minimum data acquisition rate of 10 Hz with a response of 50 Hz deemed more than sufficient. 7.3 Dimension-measuring devices Micrometers and other devices used for measuring
41、 linear dimensions shall be accurate and precise to at least 0,01 mm and shall be in accordance with ISO 3611. To obtain consistent measurements of test piece dimensions, use a flat, anvil-type micrometer. Ball-tipped or sharp anvil micrometers are not recommended for woven continuous-fibre-reinforc
42、ed ceramic composites, because the resulting measurements may be affected by the peaks and valleys of the weave. Measure test piece dimensions to within 0,02 mm. 7.4 Test fixture The fixture for the Iosipescu test is a modified asymmetric four-point bending fixture. This fixture consists of a statio
43、nary element mounted on a base plate, and a movable element capable of vertical translation guided by a stiff post. The movable element is attached to the cross-head of the testing machine. Each element clamps half of the test piece into position with a wedge-action grip that is able to compensate f
44、or minor variations in test piece width. A span of 13 mm is left unsupported between fixture halves. An alignment tool is recommended to ensure that the test piece notch is aligned with the line-of-action of the loading fixture. Figures 3 and 4 show a photograph and a schematic of such a fixture. Fi
45、gure 3 Photograph of commercially available fixture for Iosipescu test ISO 20506:2005(E) 6 ISO 2005 All rights reservedKey 1 adjustable wedge to tighten the specimen 2 stationary portion of fixture 3 load 4 specimen 5 fixture guide rod 6 wedge-adjusting screw 7 fixture attached to guide rod by linea
46、r rolling bearing Figure 4 Schematic of Iosipescu test fixture 8 Test piece 8.1 Test piece geometry The required shape and tolerances of the Iosipescu test piece are shown in Figure 2, and Table 2 contains recommended values for the dimensions of the test piece. Table 2 Recommended dimensions for Io
47、sipescu test pieces Dimension Description Value Allowance L Test piece length 76,00 mm 0,1 mm h Distance between notches 11,00 mm 0,1 mm w Test piece width 19,00 mm 0,1 mm R Notch radius 1,30 mm Notch angle 90,0 t Test piece thickness 8.2 Test piece preparation 8.2.1 Customary practices In instances
48、 where a customary machining procedure has been developed that is completely satisfactory for a class of materials (that is, it induces no unwanted surface/subsurface damage or residual stresses), this procedure shall be used. ISO 20506:2005(E) ISO 2005 All rights reserved 7 8.2.2 Standard procedure
49、s Studies to evaluate the machinability of continuous-fibre-reinforced ceramic composites have not been completed. Therefore, the standard procedure of this subclause can be viewed as starting-point guidelines, but a more stringent procedure may be necessary. All grinding or cutting shall be done with an ample supply of appropriate filtered coolant, to keep the workplace and grinding wheel constantly flooded and particles flushed. Grinding can be done in at least two stages, ranging from coarse t
