Laser Peen Bending: Simultaneous Shaping and Property Enhancement

微尺度激光喷丸弯曲(LPB)结合了激光冲击处理的疲劳性能增强效应和受控的弯曲变形，可以在不使用硬工具和外力的情况下成形微尺度金属零件。将更好地理解在靶材的照射表面和相对表面上产生压缩残余应力的工艺条件。将研究残余应力产生和弯曲机制之间的相互作用。考虑了材料的各向异性行为和长度尺度对材料性能的影响，因为激光-材料在相互作用区中与材料的晶粒度处于同一量级。单晶面心立方金属(铝和铜)将被用来研究材料的各向异性响应。诱发残余应力的空间分辨表征将使用X射线显微衍射技术进行，塑性变形程度和几何必需的位错(GND)分布将通过电子背散射衍射(EBSD)测量。这些结果将被用来验证建模和模拟工作，其中，将基于细观单晶塑性，结合压力相关的弹性模量和长度尺度引起的动态硬化，建立单晶冲击动力学效应的显式有限元分析。已建立的包括各向异性、长度尺度硬化和过程动力学的原理和开发的LPB技术可以扩展到其他微尺度制造工艺。预期的结果将有助于微制造工艺更有效、更灵活地制造更高质量的微部件。对工艺能力和限制的理解的显著提高将为新的微型部件设计打开机会。人才开发和成果传播将提高国家在微制造方面的竞争力。

Micro scale laser peen bending (LPB) combines the fatigue performance enhancement effects of laser shock processing with a controlled bending deformation to shape micro scale metallic parts without hard tooling nor external forces. Process conditions under which compressive residual stress is generated at both the irradiated and opposite surfaces of the target will be better understood. Interactions between residual stress generation and bending mechanism will be investigated. The anisotropic behavior of the material and the length scale effect on material properties will be considered since the laser-material in teraction zone is in the same order of magnitude as material grain size. Single crystal FCC metals (Al and Cu) will be used to investigate the anisotropic material response. Spatially resolved characterization of induced residual stresses will be carried out using X ray micro diffraction techniques, and the degrees of plastic deformation and geometrically necessary dislocation (GND) distributions will be measured by Electron Backscatter Diffraction (EBSD). These results will be used to validate the modeling and simulation efforts, in which, an explicit finite element analysis for shock dynamic effects on single crystals will be developed, based on meso-scale single crystal plasticity incorporating the pressure dependent elastic moduli and dynamic hardening caused by length scale.The established principles including anisotropy, hardening from length scale, and process dynamics, and developed techniques for LPB can be extended to other micro-scale manufacturing processes. Expected results will help micro manufacturing processes to make higher quality micro components more effectively and flexibly. The significantly improved understanding of process capability and limitations will open up opportunities for new micro part designs. Personnel development and dissemination of results will improve national competitiveness in micro manufacturing.