On the Mechanical Properties in Micro-Tensile Testing of Single Fiber
单纤维微拉伸力学性能测试与分析

In order to measure the mechanical properties and investigate the size effect experimentally,a high accuracy fiber micro-tensile tester(FMT-I) was developed.Corresponding data acquiring and operating system was also designed based on LabVIEW.Load cell of the tester consists of a noncontact type laser displacement sensor and a thin beam fixed at both ends,which is used to measure both tensile force acted on sample and the displacement of upper gripper,so force-displacement curve of sample may be obtained accurately.Tensile tests for micro-sized polycrystalline copper wire,316L stainless steel fiber and T300 carbon fiber were performed by using the tester.Experimental results show that(i) there is no significant size effect in tensile response of polycrystalline copper wire with diameter ranging 18-105μm;(ii) Young’s modulus of polycrystalline copper wire and 316L stainless steel fiber is in the range 43.9-60.0GPa and 102.9-111.5GPa,respectively,which are smaller than their bulk values;(iii) both ultimate strength and elongation of the 316L stainless steel fiber are decreased with the diameter decreasing;(iv) Young’s modulus and the ultimate strength of carbon fiber are 235.4±12.4GPa and 3238.2±280.8MPa,respectively,and their fracture strains are about 1.5%.Moreover,the measured results of same type samples agree well with that obtained by using commercial Instron 5848 microtester.The micro-tensile tester presented in this paper has high precision and good stability and can be used to measure the tensile properties of various fibrous materials.