Sn/3.5Ag銲錫在定拉伸應力下循環剪應變衍生之軸向蠕變—內涵時間塑性理論之研究

Abstract

In this paper, the incremental form of Endochronic Plasticity for uniaxial ratcheting induced by cyclic shear strain with constant tensile stress was employed to investigate the data of uniaxial ratcheting of Sn/3.5Ag solder at constant temperature provided by Gao et. al., under cyclic shear strain amplitudes ( ) with constant strain rate , and constant tensile stress ( ). To determine the kernel function , the volume size effect of specimen was employed. The creep compliance function converted from has three regions. The 3rd region of is linear in . If the values of were calculated based on cyclic plastic shear strain, then the ratcheting data of Gao et. al., will be in region III. This resulted in a higher dependence of in . Therefore, the definition of intrinsic time is improper to calculate uniaxial ratcheting induced by cyclic shear strain with constant tensile stress. In this paper, the intrinsic time under ratcheting was proposed in , and are functions of , and resulted in a power form of uniaxial ratcheting induced by cyclic shear strain with constant tensile stress. Under steady response, , , the results predicted were very well as compare with the experimental data. Beyond steady response, is increased very rapidly due to damage. In this paper, damage factor is defined by using the rise of ratcheting base on the difference between real and steady . By using the present Endochronic plasticity with damage, the results can predicted the data of very well.