论文标题
MG-RE合金的环状变形和疲劳行为的实验和数值分析
Experimental and numerical analysis of cyclic deformation and fatigue behavior of a Mg-RE alloy
论文作者
论文摘要
通过实验和仿真研究了MG-1MN-0.5nd（Wt。\％）合金的应变控制的疲劳。微结构由嵌入具有随机纹理的晶粒矩阵中的强质晶粒（13 \％）的分散体组成。由于质地有限，环状应变曲线的张力压缩各向异性有限。由于存在孪晶，在压缩和张力下的循环软化下发生了循环硬化。此外，损坏的样品的双体积分数取决于样品是否在张力或压缩中损坏，表明缠绕缠结发生在整个疲劳寿命中。通过计算均质化模拟了多晶合金的机械响应。使用现象学晶体可塑性模型对MG晶粒的行为进行建模，该模型构成了基础，棱镜和金字塔滑移（包括各向同性和运动型硬化）以及缠绕和detwining。从不同的环状应变幅度下的环状应力 - 应变曲线校准模型参数。数值模拟用于理解主要的变形机制，并根据每个疲劳循环中的累积塑料剪切应变来通过疲劳指标参数来预测疲劳寿命。
Strain-controlled fatigue of Mg-1Mn-0.5Nd (wt.\%) alloy were studied by experiment and simulation. The microstructure was made up of a dispersion of strongly texture grains (13\%) embedded in a matrix of grains with a random texture. The cyclic stress-strain curves showed limited tension-compression anisotropy because of the limited texture. Cyclic hardening under compression and cyclic softening under tension occurred due to the presence of twinning. Moreover, the twin volume fraction of the broken samples depended on whether the sample was broken in tension or compression, indicating that twining-detwinning occurs during the whole fatigue life. The mechanical response of the polycrystalline alloy was simulated by means of computational homogenization. The behavior of the Mg grains was modelled using a phenomenological crystal plasticity model that accounted for basal, prismatic and pyramidal slip (including isotropic and kinematic hardening) as well as twining and detwinning. The model parameters were calibrated from the cyclic stress-strain curves at different cyclic strain amplitudes. Numerical simulations were used to understand the dominant deformation mechanisms and to predict the fatigue life by means of a fatigue indicator parameter based on the accumulated plastic shear strain in each fatigue cycle.
