晶体塑性模型在微压缩实验误差分析中的应用

Crystal Plasticity Model Apply to the Error Analysis of Microcompression Test

应用基于位错密度的各向异性晶体塑性理论模型,分析了轴向压缩下Ni单晶微圆柱体的力学响应.将其与实验结果对比,验证了该理论模型的合理性.进而,以单滑移[123]取向Ni金属柱体的微压缩实验为研究对象,分析晶体取向、摩擦力、接触失配以及几何锥度等常见实验误差因素对其力学测试结果的影响.研究结果表明:在单滑移取向下,晶体取向偏差(2°)导致微圆柱体整体变形从单滑移向多滑移变形转变;受摩擦力影响的横向约束效应可以显著提高塑性应变硬化程度;接触失配导致弹性模量测试值偏低,同时使得塑性剪切滑移主方向发生显著改变;在有锥度(2°~5°)条件下,屈服应力值较无锥度情况偏低.

Anisotropic crystal plasticity model based on dislocation density is employed to investigate the mechanical response of nickel single crystalline micropillar,and is further verified by comparing its predictions with existing experimental data.Following that,we study nickel single crystalline micropillar with orientation having [123],and investigate the influence of common experimental errors of crystal orientations,friction,misalignment and taper angle,on the mechanical testing results.It is found that for the single-slip orientated micropillar,slight variation of crystal orientation leads to a transition from singleslip behavior to multi-slip deformation.Friction-affected lateral constraint shows a dramatic effect on the microcrystal strain hardening behavior.Small misalignments give rise to a decrease of elastic modulus,and change the prime slip direction in significant ways.The taper micropillar shows much smaller yield stress than no taper pillars do.