激光冲击微成形中的尺度效应研究

项目名称： 激光冲击微成形中的尺度效应研究

项目编号： No.51205232

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 机械工程学科

项目作者： 郑超

作者单位： 山东大学

项目金额： 25万元

中文摘要： 激光冲击微成形是一种新兴微塑性成形工艺，由于尺度效应对微成形过程的影响机制尚不明确，限制了该工艺在微细制造领域的广泛应用。本课题提出以激光冲击微成形中微胀形和微冲孔作为代表性工艺，探索在激光冲击诱致高应变率塑性变形和动态断裂过程中，晶粒尺寸和板材厚度的尺度效应对激光冲击微成形的影响机制。采用不同晶粒尺寸和板材厚度的紫铜和黄铜箔材，实验研究尺度效应对铜箔动态基础力学性能的影响机理, 建立考虑尺度效应的铜箔动态本构模型；实验检测结合数值模拟，材料动力学行为结合微观组织演变，明确尺度效应对微胀形时材料外在变形行为、内在微观结构演变、成形极值条件等要素的影响规律，阐明尺度效应对微冲孔时绝热剪切带形成、冲裁断面质量的影响机理。以期揭示激光冲击微成形中尺度效应的本质原因和影响机制，为增强微成形过程的可调控性、优化工艺方案和提高制品质量提供新思路。

中文关键词： 激光冲击；微变形；尺度效应；断裂行为；塑性变形

英文摘要： Microscale laser peen forming (μLPF) is a novel plastic micro-forming technology, while its application is limited due to the fact that the influence mechanism of size effects on the forming process remains unclear. In this topic, two representative technologies, micro-bulging and micro-punching, were chosen to investigate the influence of size effects of grain size and sheet thickness on μLPF under the condition of high strain rate impact loading. Quasi-static and dynamic tensile tests of pure copper foils and brass foils with various grain size and thickness were performed to study size effects on dynamic mechanical behavior. The dynamic constitutive equation considering size effects was established based on experimental data. Then the constitutive equation was employed in numerical simulation of μLPF. The influence rules of size effects on laser shock induced micro-bulging and micro-punching were summarized. The relationship between extrinsic deformation behavior and intrinsic evolvement of microstructure was investigated to understand the mechanism of size effects. A model considering size effects was developed which can be used in predicting the maximum height of foils in micro-bulging, and the technological parameters can also be optimized according to this model. The formation of adiabatic shear bands and

英文关键词： Laser shock；Micro forming；Size effect；Fracture behavior；Plastic deformation