超精密切削中单晶脆性材料脆塑转变过程

Process of ducile-brittle transition of crystal brittle materials on ultra-precision machining

借助断裂力学和位错力学的结合,提出了一种通过建立宏观力学和微观力学之间的联系模拟脆性材料脆塑转变过程的方法.该方法在同时考虑单晶材料力学性能和晶体几何结构的基础上,模拟了单晶材料在承受压剪复合应力的条件下,其内部裂纹和位错之间的相互作用机制,阐明了单晶材料在超精密切削加工中的脆塑转变过程;同时在考虑刀具对单晶材料的压剪复合作用的条件下,首次定量给出了实现单晶材料超精密切削加工的最佳刀具前角的方法,并分析了刀具刃口半径对单晶材料脆塑转变过程的影响;最后通过实验对研究结果进行了验证.

By combination of fracture mechanics and dislocation mechanics, the method of simulating the process of ducile-brittle transition of brittle material based on the connection between macromechanics and mi- cromechanics was discussed. The single crystal material mechanical property and crystal geometric structure was given. In press-shear complicated stress condition, interaction mechanism between its internal cracks and dislocation was demonstrated, its process of ducile-brittle transition on ultra-precision machining was illustra- ted. Considering cutting tool to crystal material press-shear mixed effect, the method of realizing the best tool＇ s rake angle was given and the influence of the tool edge radius on the process of ducile-brittle transition of crystal brittle materials on the ultra precision machining was analyzed. Finally, research results were tested and verified through the experiments.