柴油机连杆的残余应力和疲劳强度试验研究

Experimental Investigation on Residual Stress and Fatigue Strength of Diesel Engine Connecting Rods

连杆在柴油机工作过程中承受复杂的载荷,而残余应力会导致连杆等零部件的早期失效。以某柴油机连杆为对象,系统地开展了2种不同结构设计方案的残余应力测量分析,并对优选出的方案进行疲劳强度测试。试验结果显示,2种连杆方案的残余应力分布情况呈现出相似的特点,分布均匀,应力值主要分布在400 MPa左右,但小头与杆身连接处局部仍存在残余应力值的不同。疲劳试验中连杆的断裂位置容易发生在小头与杆身连接处,连杆允许的强化系数在1.15~1.20之间。

Connecting rod is subjected to complex loads during engine operation,and the residual stress can lead to early failure of components such as connecting rod.The residual stress measurement and analysis under two different structural design schemes and surface process conditions of a diesel engine connecting rod were carried out and the fatigue strength of the better design scheme was studied by experiment.The test results show that the residual stress distribution of the two connecting rod schemes is similar,the distri⁃bution is uniform,and the stress value is mainly distributed around 400 MPa,but there were still obvious differences of the residual stress values at the connection between the small head and the shaft.In the fatigue test,the fracture position of the connecting rod were easy to occur at the connection between the small head hole and the shaft,and the allowable strengthening coefficient of the connecting rod was between 1.15 and 1.20.