1、 ISO 2014 Fine ceramics (advanced ceramics, advanced technical ceramics) Ceramic composites Determination of the degree of misalignment in uniaxial mechanical tests Cramiques techniques Cramiques composites Dtermination du degr de non-alignement lors des essais mcaniques uniaxiaux INTERNATIONAL STAN
2、DARD ISO 17161 First edition 2014-04-01 Reference number ISO 17161:2014(E) ISO 17161:2014(E)ii ISO 2014 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2014 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any
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4、neva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ISO 17161:2014(E) ISO 2014 All rights reserved iii Contents Page Foreword iv 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 3.1 General . 1 3.2 Type of defects 2 4
5、 Principle 2 5 Apparatus . 3 5.1 Test machine . 3 5.2 Load train. 4 5.3 Strain gauges . 4 5.4 Data recording system 4 5.5 Micrometers 4 6 Reference test specimens 4 7 Reference test specimen preparation 6 7.1 Adhesion of strain gauges 6 7.2 Reference test specimen validity . 6 8 Test procedure 6 8.1
6、 General . 6 8.2 Correction of the torsion defect . 6 8.3 Correction of the C defect 7 8.4 Correction of the S defect . 8 8.5 Final verification before starting a series of measurements on CMCs 9 9 Test report . 9 Bibliography .10 ISO 17161:2014(E) Foreword ISO (the International Organization for St
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13、is ISO/TC 206, Fine ceramics.iv ISO 2014 All rights reserved INTERNATIONAL ST ANDARD ISO 17161:2014(E) Fine ceramics (advanced ceramics, advanced technical ceramics) Ceramic composites Determination of the degree of misalignment in uniaxial mechanical tests 1 Scope This International Standard descri
14、bes a procedure to verify the degree of misalignment of the load train of the test machines using a reference test specimen uniformly loaded in tension or in compression, and to give indications in order to correct defects such as torsion and bending. This International Standard is not intended to p
15、rovide a quantitative and acceptable limit before the testing of ceramic matrix composites with a fibre reinforcement: unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 x 3) loaded along one principal axis of reinforcement. This limit depends on the sensitivity of each type of
16、composite to the misalignment defect. NOTE 1 This limit is to be defined between the testing establishment and the customer. NOTE 2 Monolithic ceramics are very sensitive to misalignment defects while CMCs (ceramic matrix composite) in general are moderately sensitive to them. 2 Normative references
17、 The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 36
18、11, Geometrical product specifications (GPS) Dimensional measuring equipment: Micrometers for external measurements Design and metrological characteristics ISO 7500-1, Metallic materials Verification of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and ca
19、libration of the force-measuring system ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories CEN/TR 13233:2007, Advanced technical ceramics Notations and symbols (to be replaced by future ISO NP 19634) 3 T erms a nd definiti ons For the purposes of this docu
20、ment, the terms and definitions given in CEN/TR 13233:2007 (to be replaced by future ISO NP 19634) and the following apply. 3.1 General 3.1.1 calibrated length l part of the reference test specimen which has a uniform and minimum cross-section area ISO 2014 All rights reserved 1 ISO 17161:2014(E) 3.
21、1.2 width b width of the reference test specimen in the calibrated length 3.1.3 thickness h thickness of the reference test specimen in the calibrated length 3.2 Type of defects 3.2.1 C-type magnitude angle between the loading axis of each of the two grips Note 1 to entry: See Figure 1. 3.2.2 S-type
22、 magnitude d distance between the loading axis when they are parallel Note 1 to entry: See Figure 2. 3.2.3 torsion defect magnitude angle between the gripping planes Note 1 to entry: See Figure 3. 4 Principle A rectangular cross section of a reference test specimen (Clause 7) equipped with 10 strain
23、 gauges is loaded in tension or in compression, up to a load corresponding to 10 % of the nominal load capacity of the load cell used for the tests of CMCs. The stress corresponding to this value shall not exceed 50 % of the elasticity limit of the material used for the reference test specimen. The
24、readings obtained from the strain gauges bonded on the calibrated length of the reference test specimen allow the determination of the degree of misalignment. The positioning of strain gauges is such that it indicates the magnitude of defects. These magnitudes allow the correction, in a practical ma
25、nner, of the different types of defects: bending defects, either C (Figure 1) or S (Figure 2); torsion (Figure 3). The indications for correction are obtained by comparing the experimental readings of the strain gauges to values from charts established from numerical simulations.2 ISO 2014 All right
26、s reserved ISO 17161:2014(E) Figure 1 C defect magnitude d Figure 2 S defect magnitude Key 1 lower grip 2 upper grip Figure 3 Torsion defect magnitude 5 Apparatus 5.1 Test machine The configuration of the test machine, including the load train and load cell, shall be identical to the test machine us
27、ed for the tests on the CMCs and shall be in accordance with ISO 7500-1. ISO 2014 All rights reserved 3 ISO 17161:2014(E) 5.2 Load train The load train configuration shall ensure that the load indicated by the load cell and the load experienced by the test specimen are the same. The grip design shal
28、l prevent the test specimen from slipping. The choice of gripping system will depend on material, on test specimen design, and on alignment requirements. 5.3 Strain gauges The principle of this method requires the use of strain gauges with an active surface equal to or smaller than 4 2,5 mm 2 . Furt
29、hermore, the distance between the edge of the test reference specimen and the longitudinal axis of the strain gauge shall be such as to avoid edge effects. A minimum distance of 2 mm is required. Care shall be taken to ensure that the strain gauge readings are not influenced by the surface preparati
30、on and the adhesive used. 5.4 Data recording system A calibrated recorder can be used to record load/strain curves. The use of a data recording system combined with an analogue recorder is recommended. All strain measuring equipment and data acquisition systems shall be calibrated as appropriate. Ty
31、pically they shall have an accuracy to within 0,5 % of indicated reading or 3 microstrain, whichever is greater, and a resolution of 1 microstrain. 5.5 Micrometers Micrometers used for the measurement of the dimensions of the reference test specimen shall be in accordance with ISO 3611. 6 Reference
32、test specimens The degree of misalignment of the load train of the test machine is verified by performing tests at room temperature with the following reference test specimen: dimensions: see Figure 4 and Table 1; material: steel ISO reference; location of the strain gauges: see Figure 4. If another
33、 reference test specimen is used, it is necessary to establish a new series of charts. Plan parallelism of the faces: 0,02 mm. Dimensions of the strain gauges, in millimetres: .4 ISO 2014 All rights reserved ISO 17161:2014(E) Dimensions in millimetres 1 2 1 3 6 5 1 2 3 3 4 7 8 ac 25 25 bb h L L l 1
34、-45 +45 c a NOTE 1 Gauge n 5 is a rosette allowing measurements of strains parallel to 1 and to 45. NOTE 2 Keys a and c indicate each surface. Figure 4 Dimensions of the reference test specimen and location of the strain gauges ISO 2014 All rights reserved 5 ISO 17161:2014(E) 7 Reference test specim
35、en preparation 7.1 Adhesion of strain gauges It is essential to protect strain gauges and adhesives from effects due to moisture and other degrading contaminants. Therefore, it is recommended that after installation of the strain gauges, a layer of protective coating material such as strain-gauge-gr
36、ade silicone rubber is applied. 7.2 Reference test specimen validity Periodically check the response of the strain gauges by comparing Youngs modulus of the steel, the reference test specimen is made from, determined for each location of the strain gauges, to the value of Youngs modulus determined d
37、uring the first utilization of the reference test specimen by the same method. The difference between these two values shall not exceed 5 %. This value shall be indicated more accurately when more experimental results are made available. It is recommended to do this verification once a year. 8 Test
38、procedure 8.1 General The procedure consists of the following sequence. 8.2 Correction of the torsion defect The reference test specimen is gripped while keeping the uniaxial load at 0 by using a specific mounting tool that secures a strict parallelism between the loading axis and the longitudinal a
39、xis of the reference test specimen. To check it, compare responses given by gauges 1 and 2. Record the reading of strain gauges at position 5 and calculate the distortion ( +45 -45 ). This value allows the determination of the torsion defect using chart 1 (see Figure 5). If this value is higher than
40、 the authorized limit, a correction of the angle between the two grips shall be done. The above procedure is repeated until the value of the angle is less than or equal to the authorized limit.6 ISO 2014 All rights reserved ISO 17161:2014(E) NOTE is in degrees and strains are dimensionless: = 1 287,
41、6 12 . Figure 5 Chart 1 Torsion defect 8.3 Correction of the C defect Load the reference test specimen to stretch the load train. Record the longitudinal readings of the strain gauges located at position 4 ( 1,4 ) and 5 ( 1,5 ): see specimen drawing in Figure 4 given by strain gauges n 4 and n 5, re
42、spectively, and see dimensions in Table 1. Calculate the value of ( 1,4 1,5 ) and determine the C defect using chart 2 (see Figure 6). If this value is higher than the authorized limit, a correction of the angle between the loading axis of each of the two grips shall be done. The above procedure is
43、repeated until the value of the angle is less or equal to the authorized limit. Then unload the reference test specimen. Table 1 Specimen dimensions Dimensions mm Tolerances mm length with strain gauges, l 100 0,1 thickness, t 4 0,1 width, b 18 0,1 a L = 200 mm is recommended. ISO 2014 All rights re
44、served 7 ISO 17161:2014(E) NOTE is in degrees and strains are dimensionless: = 790 ( 1,4 1,5 ). Figure 6 Chart 2 C defect 8.4 Correction of the S defect Load the reference test specimen to stretch the load train. Record the longitudinal deformations of the strain gauges located at positions 1, 2, 3,
45、 6, 7, and 8 ( 1,1 , 1,2 , 1,3 , 1,6 , 1,7 , and 1,8respectively); see specimen drawing in Figure 4 and dimensions in Table 1. Calculate the value of ( 1,8+ 1,7 2 1,3 ) and of ( 1,1+ 1,2 2 1,6 ). The higher of these two values is then used to determine the S defect from chart 3 (see Figure 7). If th
46、is value is higher than the authorized limit, a correction of the distance d between the loading axes when they are parallel shall be done. The above procedure is repeated until the value of the distance d is less than or equal to the authorized limit. Then unload the reference test specimen. Dimens
47、ions in millimetres d NOTE Strains are dimensionless: d = 371,43 ( 1,8+ 1,7 2 1,3 ). Figure 7 Chart 3 S defect8 ISO 2014 All rights reserved ISO 17161:2014(E) 8.5 Final v erification b efor e starting a series o f measur ements on CMCs Load the reference test specimen up to 50 % of its elastic limit
48、. Record simultaneously all the longitudinal deformations given by strain gauges located at positions 1 to 8 ( 1,1 , 1,2 , 1,3 , 1,4 , 1,5 , 1,6 , 1,7 , and 1,8 , respectively). Apply the procedures described in 8.3 and 8.4 for the calculation and correction of the C and S defects, respectively. Then use the values of deformations in order to determine the percent bending strain (PBS). PBS is the bending strain times 100 divided by the axial strain. Un
