摩擦因数与弹丸形变对超声喷丸纯铜的影响研究

Effect of friction factor and bullet deformation on ultrasonic peening of pure copper

在已有的超声喷丸有限元模型中,绝大多数都忽略了弹丸的弹性、塑性变形对数值模拟结果的影响。同时,关于弹丸表面与受喷材料表面之间的摩擦因数对超声喷丸数值预测结果的影响规律,目前也鲜有报道。为此,以纯铜试样为研究对象,结合超声喷丸实验和数值模拟过程,研究了摩擦因数与弹丸形变对超声喷丸纯铜的影响规律。首先,基于ABAQUS平台建立了单丸粒超声喷丸三维有限元模型;然后,设计了单丸粒超声喷丸实验,依据实验条件分析了喷丸距离对速度的影响,将实验工况输入仿真模型,并分别从弹丸速度、凹坑形貌两方面比较了实验与仿真结果;最后,分别采用刚性丸、弹性丸、弹塑性丸,在摩擦因数为0.1、0.2、0.3、0.4、0.5的工况下,对纯铜试样进行了超声喷丸数值模拟,对受喷表面的形貌、残余应力进行了分析。研究结果表明:当弹丸与纯铜表面之间的摩擦因数大于0.2时,摩擦因数对超声喷丸纯铜形成的凹坑形貌和残余应力的影响不再显著;超声喷丸纯铜形成的凹坑尺寸、残余压应力深度、最大压应力和表面残余拉应力随弹丸与纯铜之间接触刚度的增大而增大。该研究结果对超声喷丸的数值建模具有重要的指导意义。

In the existing finite element models of ultrasonic shot peening,most of them ignore the influence of elastic and plastic deformation of the projectile on the numerical simulation results.There are few reports on the influence of the friction coefficient between the surface of the projectile and the surface of the sprayed material on the numerical prediction results of ultrasonic shot peening.Therefore,taking pure copper as the research object,the influence of friction coefficient and projectile deformation on pure copper by ultrasonic shot peening was studied by combining the ultrasonic shot peening experiment and numerical simulation process.Firstly,a three-dimensional finite element model of single ultrasonic shot peening was established based on ABAQUS platform.Then,the single ultrasonic shot peening experiment was designed,and the influence of shot peening distance on velocity was analyzed according to the experimental conditions.The experimental conditions were input into the simulation model,and the experimental and simulation results were compared from the aspects of shot velocity and indentation morphology.Finally,under the condition of friction coefficient of 0.1,0.2,0.3,0.4 and 0.5,the ultrasonic shot peening numerical simulation of pure copper specimens was carried out by respectively using rigid shot,elastic shot and elastic-plastic shot.The surface morphology and residual stress of the treated surface were analyzed.The obtained results show that when the friction coefficient between the shot and the pure copper is larger than 0.2,the influence of the friction coefficient on the morphology of indentations and residual stress formed by ultrasonic peening of pure copper is no longer significant.With the increase of the contact stiffness between the shot and the pure copper,the indentation size,the depth of the compressive residual stress field,the maximum compressive residual stress and the surface tensile residual stress induced by ultrasonic shot peening of pure copper increase accordingly.The research results have important guiding significance for the numerical modeling of ultrasonic shot peening.