Coupling effect and its correction on experimental results of three-point bend
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摘要: 三点弯曲试验中存在着弯剪耦合效应,通过引入弯剪耦合系数,利用Tsai-Hill强度准则建立弯剪耦合方程,定量分析了弯剪耦合作用,提出了复合材料三点弯曲试验结果修正方法。研究表明:弯剪耦合效应会对复合材料三点弯曲试验结果产生比较大的影响。在弯剪耦合效应作用下,弯曲强度测试误差随弯剪强度比的增大而增大,剪切强度的测试误差随弯剪强度比的增大而减小。当弯剪耦合系数一定时,由耦合引起的测试误差的大小取决于梁的跨高比与材料的弯剪强度比的比值。对试验结果修正后,增加了不同跨高比下的三点弯曲试验结果的可比性,反映了材料的固有属性。Abstract: Coupling of flexure and shear exists in three-point bend beams. The coupling coefficients of flexure and shear were introduced,and the coupling equations of flexure and shear were deduced based on Tsaicriteria. The coupling effect of flexure and shear was analyzed quantificationally,and the modification method of the experimental results was presented. It was shown that the experimental results of three-point bend were influenced obviously by the coupling of flexure and shear. The flexural strength error from the coupling effect increased with the flexural-shear strength ratio, whereas the shear strength error decreased with it. For the given coupling coefficients of flexure and shear,the test errors were determined by the division of span-height ratio into the flexural-shear strength ratio. The experimental results were modified by the modification methods,and the correctional results of three-point bend on different span-height ratios became more comparable. The inherent properties were reflected by the correctional results.
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Key words:
- three-point bend /
- flexural strength /
- shear strength /
- coupling /
- correction method
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