An Analysis on Multiaxial Loading Fatigue through Constitutive Equation Derived in Terms of Dislocation Dynamics

多重压力是指周围的压力集中的位置，如notch root和crack tip。在目前的研究中，循环神经酰胺、裂缝打开置换和循环压力神经酰胺的反应是在无线铜中计算裂缝尖端的弹性-塑料精元素方法的作用下计算的，在使用分离动力学概念的地方，使用静态方程的情况下，被雇用的地方。Furthermore，用网格方法测量了张力：网格的置换物通过激光显微镜观察在裂缝提示周围进行了测量。首先，该分析是为在Through-thickness中心-裂缝的特定对象中进行的循环变形而进行的。类似的计算是为了在模式II加载下实现的预压缩张力/剪切规格，主要结果被捕获为汇总后。（1）负载置换响应计算为through-thickness center-cracked specimen在模式下，我加载了良好的循环硬化行为，并在早期的循环退化过程中与实验数据达成了良好的协议。（2）衡量的裂缝打开置换趋势，以达到稳定状态，通过它早期增加了在负载控制条件下的阶段，那么计算很好地表达了。（3）cyclic strain during one load cycle and the amount of strain concentration tend to decrease with increasing number of cycle loading around the crack tip。“计算的描述很好，这是一种循环神经系统行为。”（4）The strain calculated around the crack tip in the compact tension/shear specimen subjected to the mode II loading developes in the diredction of\=0 just ahead of the crack tip and in the direction of\= -30 in the region distant from the crack tip。

Multiaial stress is induced around stress-concentrated location such as notch root and crack tip. In the present study, the cyclic strain, crack opening displacement and cyclic stress-strain response were calculated in the vicinity of crack tip by means of elastic-plastic finite element method in annealed copper, where the constitutive equation derived from using the concept of dislocation dynamics was employed. Furthermore, strain was measured by the grid method : the displacement of the grid was measured through the laser microscope observation around the crack tip.Firstly, the analysis was made for the cyclic deformation around the crack tip in the through-thickness center-cracked specimen subjected to the model loading.Secondly, the similar calculation was achieved for the pre-cracked compact tension/shear specimen under the mode II loading.Main results obtained are summarized as follows.(1)Load-displacement response calculated for the through-thickness center-cracked specimen under the mode I loading expressed well the cyclic hardening behavior in the early cyclic deformation process, being in good agreement with the experimental data.(2)The measured crack opening displacement tends to reach the stabe state through it's early increasing stage under the load-controlled condition, which is well expressed by the calculation.(3)The variation range of the cyclic strain during one load cycle and the amount of strain concentration tend to decrease with increasing number of cyclic loading around the crack tip. The Calculation describes quite well such cyclic strain behaviors.(4)The strain calculated around the crack tip in the compact tension/shear specimen subjected to the mode II loading developes in the diredction of θ=0゜just ahead of the crack tip and in the direction of θ= -30゜ in the region distant from the crack tip.