【作者】 倪敏雄；

【导师】 周建忠；

【作者基本信息】 江苏大学 ， 机械制造及其自动化， 2006， 硕士

【摘要】 激光喷丸成形是利用高功率脉冲激光器产生的冲击波压力在板料内部诱导出不平衡的残余应力场，通过残余应力引发的弯曲力矩促使板料发生塑性弯曲变形的一种板料成形技术。本文系统地研究了激光喷丸成形的基本过程和变形原理，对不同参数条件下激光喷丸板料的弯曲变形进行了实验研究和有限元数值模拟分析，主要工作有以下几点：从激光与材料相互作用的过程出发分析了激光喷丸诱导冲击波的基本过程和物理机制，探讨了在高幅冲击波加载下金属材料的力学响应以及冲击波诱导残余应力的基本过程，分析了影响残余应力场大小和分布的一些主要因素。详细研究了残余应力作用下板料发生弯曲变形的机制，以力学理论为依据，建立了激光喷丸成形中残余应力场与板料弯曲变形之间的分析模型，获得了激光喷丸后板料弯曲曲率和弧高度值与参数之间的基本关系式，并指出了影响激光喷丸板料弯曲变形的一些主要影响因素。实验着重研究了激光脉冲参数、喷丸次数、喷丸覆盖率、喷丸条带间距以及板料厚度等与板料弯曲变形特性之间的关系，获得了不同参数下激光喷丸板料弯曲变形的基本规律，并对激光喷丸后试样表面残余应力值和表面质量进行了测试和分析。结果表明，激光喷丸后弯曲变形的板料上下表面均存在有益的残余压应力值和良好的表面质量。在实验研究的基础上，利用ABAQUS软件对激光喷丸诱导的残余应力场以及板料的弯曲变形过程进行了有限元数值模拟，模拟获得的结论与理论分析和实验结果基本一致，表明采用有限元方法可以较好地预测激光喷丸后板料的变形形状以及残余应场的分布情况。研究所取得的成果为激光喷丸成形中参数的合理优化和板料变形过程的控制提供了积极的指导意义。更多还原

【Abstract】 The laser peen forming (LPF) is an emerging modern process of metal plate bending. It uses laser-induced shock wave pressure to induce unbalanced residual stress field in the sheet metal, then the moment of the residual stress causes the sheet metal to develop plastic bending deformation. In this paper, the primary process and mechanism of LPF are studied in detail, then the residual stress field induced by laser peeing and the bending deformation of sheet metal are researched by experiment and finite element method (FEM) simulation. The main contents in this paper were showed as following:The basic process and physics mechanism of laser shock wave are analyzed from the process of interaction between laser and materials. Then the dynamic response of sheet metal acted on the laser shock wave loading and the generation principle of residual stress were discussed. Afterwards some major factors which influence residual stress field were analyzed.The primary mechanism of the sheet’s bending deformation caused by residual stress was researched in detail. In terms of mechanics theory, the analysis model that residual stress brought sheet’s bending deformation in the LFP was established, then the relationship between the metal’s curve and processing parameters was obtained. At last the influencing factors of LPF were discussed.The relationship between laser pulse parameters, peening numbers, peening coverage, peening space, thickness of the plate and the character of sheet forming were investigated by the experiments. Then the surface residual stress and surface qualities of sheet metal by LPF were observed and analyzed. The results of experiment indicated that both upper and lower layers of the deformed plate existed useful residual compressive stresses, and the laser peened surfaces were in good surface quality.Based on the above experiments, the processes of residual stress field and sheet’s bending deformation induced by laser peening were simulated by using ABAQUS software.The simulation results were agreement with the analytic results and the experimental results. The gained conclusions have great significance for the purpose of optimizing the processing parameters and the controlling of LPF.更多还原