BS EN ISO 20504:2016 pdf download – Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for compressive behaviour of continuous fibre- reinforced composites at room temperature (ISO 20504:2006)

BS EN ISO 20504:2016 pdf download – Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for compressive behaviour of continuous fibre- reinforced composites at room temperature (ISO 20504:2006) 5.2Load train The load train is composed of movable and fixed cross-heads, the loading rods and the grips or platens. Loadtrain couplers may additionally be used to connect the grips or platens to the loading rods. The load train shall align the test specimen axis with the direction of force application without introducingbending or torsion in the test specimen. The misalignment of the test specimen shall be verified anddocumented in accordance with the procedure described in Annex B. The maximum percent bending shall notexceed 5 % at an average axial strain of 500× 10-6. There are two alternative means of force application: a) Compression platens are connected to the force transducer and the moving cross-head.The parallelism of these platens shall be better than 0,01 mm, in the loading area and the faces of the platens shall beperpendicular to the force application direction. NOTE1 The use of platens is not recommended for compression testing of 1D and 2D materials with smallthicknesses because of buckling. NOTE2 A compliant interlayer material (composed only of paper or cardboard), between the test specimen andplatens, can be used for testing macroscopically inhomogeneous materials to ensure uniform contact pressure. When the dimensions of the test specimen are such that buckling may occur, it is recommended to useantibuckling devices similar to those described in lSO 14126.These devices should not introduceparasitic stresses (i.e.stresses other than the uniform , axial stress) during loading of the test specimen. b) Grips are used to clamp and load the test specimen. The grip design shall prevent the test specimen from slipping and the grips shall align the test specimen axis with that of the applied force. Alignment shall be verified and documented in accordance with, for example,the procedure described inAnnex B. 5.3Strain measurement 5.3.1 General For continuous measurement of the longitudinal deformation as a function of the applied force, either straingauges or a suitable extensometer may be used.Use an extensometer that meets the requirements of at leastclass 1 in ISO 9513.Measurement of longitudinal deformation over a length as long as possible within thegauge section length of the test specimen is recommended. 5.3.2Strain gauges Strain gauges are used for the verification of the alignment on the test specimen. They may also be used todetermine...