圆杆件激光冲击强化的有限元分析和实验研究

发布时间：2019-04-20 16:08

【摘要】：激光冲击强化是一种新型的表面强化技术,它使用高能量和短脉冲的激光束作为工具,对材料表面进行强化处理。本文运用数值模拟与实验相结合的研究方法,研究激光冲击铝合金圆杆件后,材料中残余应力的分布情况及其对材料疲劳寿命的影响,主要内容如下:首先,在激光冲击波产生原理和气体动力学理论的基础上,对激光冲击波诱导的峰值压力在无约束和有约束模型中的传播过程进行比较研究。根据爆轰波的C-J理论,阐述了激光诱导的应力场形成原理,讨论了冲击波在约束模型下的传播机理,建立了激光冲击强化金属材料的力学模型,对激光诱导产生的峰值压力进行了公式的推导和估算。其次,使用ABAQUS数值模拟软件建立铝合金圆杆的有限元模型,来模拟激光冲击铝合金圆柱杆后,杆内应力波的传播与衰减过程,并分别分析了激光单点和多点冲击后,圆柱杆端面和圆周面的残余应力分布情况,研究了圆杆直径因素对残余应力分布规律的影响。通过比较激光冲击在曲面上残余应力分布规律的差异,探究了激光冲击强化在曲面上残余应力的分布特点。最后,以2024铝合金圆杆件为材料进行激光冲击强化实验。对强化后和未强化的试样进行疲劳试验。对比分析激光冲击强化对圆杆件疲劳寿命的影响。而且,通过扫描电子显微镜对试样疲劳断口的微观形貌特征进行了观测,从微观角度解释了激光冲击强化铝合金圆杆件的延寿机理。
[Abstract]:Laser shock hardening is a new surface strengthening technology, which uses high energy and short pulse laser beam as a tool to strengthen the surface of materials. In this paper, the distribution of residual stress and its influence on fatigue life of aluminum alloy rod after laser shock are studied by means of numerical simulation and experiment. The main contents are as follows: first of all, the distribution of the residual stress in the material and its influence on the fatigue life of the material are studied. Based on the generation principle of laser shock wave and the theory of gas dynamics, the propagation process of peak pressure induced by laser shock wave in unconstrained and constrained models is compared. The formation principle of laser-induced stress field and the propagation mechanism of shock wave under the constraint model are discussed. The mechanical model of laser shock hardening metal material is established according to the theory of C ~ (? J) of detonation wave, and the mechanism of laser-induced stress field formation is discussed in this paper. The formula of peak pressure induced by laser is derived and estimated. Secondly, the finite element model of aluminum alloy circular rod is established by using ABAQUS numerical simulation software to simulate the propagation and attenuation of stress wave in aluminum alloy cylindrical rod after laser shock, and the single-point and multi-point laser shock are analyzed respectively. The distribution of residual stress at the end and circumference of cylindrical rod is studied. The influence of diameter factor on the distribution of residual stress is studied. By comparing the difference of the residual stress distribution on the surface of laser shock, the distribution characteristics of the residual stress on the surface strengthened by laser shock are discussed. Finally, the laser shock strengthening experiment of 2024 aluminum alloy circular bar was carried out. Fatigue tests were carried out on the strengthened and unstrengthened specimens. The influence of laser shock strengthening on the fatigue life of circular member is analyzed. In addition, the micro-morphology of fatigue fracture was observed by scanning electron microscope, and the mechanism of prolonging the life of aluminum alloy round bar strengthened by laser shock was explained from the micro-point of view.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG665

【参考文献】