非垂直冲击对冷喷涂铝基涂层残余应力影响的数值研究

Numerical Study on Effects of Oblique Impact on Residual Stress of Cold Spray Al-base Coating

对于非垂直入射的颗粒在冷喷涂沉积过程中产生的残余应力进行研究,旨在分析该状况下残余应力的变化趋势及其对沉积特性的影响。采用ABAQUS/Explicit有限元分析软件,以Al/Al作为粒子和基体的材料进行模拟,研究了粒子倾斜冲击对残余应力的影响,并添加无限元素层以增强数值稳定性。结果表明:颗粒以不同角度沉积基体的过程分为4个步骤,在冲击、瞬态喷丸和结合过程中残余应力变化幅度较大,在热冷却阶段残余应力趋于稳定。随着等效塑性应变的急剧增加,压缩残余应力会而逐渐减小,这意味着在这些倾斜角减小的区域不易发生绝热剪切失稳现象,从而影响沉积效率。在70°~80°存在一个合理入射角,该区域等效塑性应变较小,颗粒和基材的最大界面压力达到峰值。此时,残余压缩应力也可能达到最大,这会对绝热剪切失稳产生促进作用,进而加强了粒子与基体之间的结合。

Aiming to study the effect of particle incident angle on residual stress of cold spray by numerical method,the change trend of residual stress under this condition and its effects on the deposition characteristics were analyzed.Using ABAQUS/Explicit finite element analysis software,taking Al/Al the material of particles and substrate as the material to simulate,the effects of oblique impact on the residual stress of cold spray Al-based coating were investigated.By adding infinite element layer,the numerical stability was enhanced.The results show that the process by which particles deposition the substrate at different angles is divided into four steps.The residual stress varies greatly during impact,transient shot peening and bonding,and tends to be stable during thermal cooling.As the rapid increase of equivalent plastic strain,the compression residual stress gradually decrease,which means that insulation shearing in these areas where the tilt angle decreases is not easily occurred,thus affecting the deposition efficiency.There is a reasonable incidence angle between 70°and 80°.The equivalent plastic strain in this area is small,at which the residual stress value and interface pressure of particles and substrates may reach the maximum.At this point,the residual compressive stress also reaches the maxmum,which can promote the adiabatic shear instability and furtherly strengthen the bonding between particles and substrate.