等离子喷涂FeCrBSi涂层接触应力有限元分析

Finite Element Analysis for Contact Stress of Plasma Sprayed FeCrBSi Coating

针对传统宏观力学研究涂层的局限性,开展了基于Hertz理论的等离子喷涂Fe Cr BSi涂层有限元数值模拟研究,得到了涂层表面在不同载荷和摩擦力作用下,涂层主应力与剪切应力的分布特征。分析结果表明:主应力是接触疲劳失效的临界应力,而剪切应力则导致涂层在微缺陷处在较短的时间内诱发萌生微裂纹,不同主应力与剪切应力的协同作用使得涂层失效模式呈现多元化,应力是涂层失效的主要驱动力。摩擦系数的增加导致剪切应力急剧增加,剪切应力造成涂层表面的塑性流动。当塑性流动超过材料的变形极限时,造成表面材料开裂,在循环作用下最终形成裂纹。同时摩擦系数的增加加大了涂层与对摩轴承直接接触相互损伤的可能性。

In view of the limitations of traditional macro-mechanics in the surface coating study, the Hertz theory was introduced into the finite element analysis of the plasma sprayed Fe Cr BSi coating. The distribution of principal stress and shear stress in the coating is obtained under different loads and frictions. Results show that the principal stress is the critical stress of contact fatigue failure, the micro-defects in the coating induce micro-cracks by shear stress in a short time. The synergism of different principal stress and shear stress diversify the coating failure mode, but they are the main driving force of coating failure. The increase of the friction coefficient raises the shear stress sharply, consequently resulting in the plastic flow of the coating surface. When the plastic flow deformation of the material exceeds the limit, cracking of the surface occurs. Meanwhile, the higher friction coefficient of the coating could increase the risk of damage between the coating and the friction bearings.