激光冲击悬臂薄板变形的理论分析和实验研究

目的激光喷丸技术是一种利用激光诱导等离子体冲击波产生的力学效应来改善材料的机械性能的表面强化技术,但是在激光喷丸过程中,由于高压冲击波的作用会使薄壁件发生宏观变形,造成零件失效,为了控制激光冲击板料宏观变形过程,因此有必要对激光冲击下板料的力学变形特性进行研究。方法通过对激光冲击载荷作用下悬臂板变形过程的理论分析,建立了板料在激光冲击下的受力变形模型,对激光作用下板料的变形量公式进行了理论推导计算,研究了板料变形量与板料厚度、激光能量等之间的相互关系,并通过单点冲击与多点搭接冲击实验和有限元分析相结合的方式验证了理论公式的准确性。结果依据所建立的板料变形理论计算得到的理论值、实验值和有限元分析结果都较为接近,其中板料变形量对厚度的变化十分敏感,在设定条件下,当板材厚度大于3 mm时,板材变形很小,几乎不产生明显的变形。结论板料变形量随着激光能量和光斑数量的增大而增大,板材的厚度对变形量的影响很大,是设计激光喷丸参数时必须考虑的要素。

Theoretical Analysis and Experimental Study on Deformation of Cantilever Plate Induced by Laser Peening

Laser peening is a novel surface strengthening technique used to improve mechanical property of materials by utilizing mechanical effect produced by laser induced plasma shock wave. However, during the process of laser peening, effects of high pressure shock wave may cause macroscopical deformation of thin-walled workpieces and result in failure of parts. The work aims to clarify the characteristics of mechanical deformation characteristics of plate subject to laser shock in order to control macroscopical deformation process of plate subject to laser shock. Based on theoretical analysis of deformation process of cantilever slab under laser shock loading, a model of strained deformation of cantilever plate under laser shock was constituted and the deformation formula of plate under laser effects was calculated by theoretical derivation. The relationship between the plate deformation and various parameters such as laser energy, plate thickness was also studied. Accuracy of the theoretical formula was verified by combining single-point & multipoint lap shock experiments and finite element analysis. Experimental results showed that theoretical value, experiment value and finite element analysis results acquired by established theoretical calculation of plate were similar. The plate deformation was sensitive to variation in thickness. Under given conditions, minor plate deformation and even no obvious deformation appeared when the thickness exceeded 3 mm. Plate deformation increases with the increase of laser energy and spot number. Plate thickness has great influence on deformation and shall be considered when designing laser peening parameters.