动车组车轮多轴疲劳强度分析及修正

Analysis and Correction of Multi-axial Fatigue Strength of EMU Wheels

国内外研究结构多轴疲劳强度理论与方法的文献较为多见,尤其是金属母材的疲劳评估准则与行业标准都相对成熟。但即使在同样载荷作用下的同样结构进行多轴疲劳评估,各种评估方法所得结果都会有一定的差异。分别用Sines准则、Crossland准则和Kakuno-Kawada准则对动车组车轮进行多轴疲劳强度计算,研究对比各种方法得出的安全系数的大小,得到安全性最高的疲劳强度评估方法。计算结果表明,Kakuno-Kawada准则相对于其他多轴疲劳评估准则安全系数最小,安全度最高。由于Kakuno-Kawada准则中参数只考虑扭转应力对车轮的影响,评估结果存在一定的局限性。对该方法进行了修正,将对称扭转疲劳极限t-1与对称弯曲疲劳极限f-1的比值作为限定条件,使修正后的Kakuno-Kawada准则更符合动车组车轮实际运行受力情况,安全系数小于原准则,说明改进的Kakuno-Kawada准则计算方法更加安全有效,有利于保证动车组车轮的运行安全。

Domestic and international literatures on the theory and methods of structural multiaxial fatigue strength are common,in particular,the fatigue evaluation criteria and industry standards of metal base materials are relatively mature.However,even if the same structure under the same load is subjected to multi-axis fatigue assessment,the fatigue strength results obtained from various evaluation methods are different.The three criteria of Sines,Crossland and Kakuno-Kawada were used to calculate the multiaxial fatigue strength of EMU wheels.The safety factors of each criterion were compared to obtain the highest safety fatigue strength assessment method.The calculation results show that the safety factor of Kakuno-Kawada criterion is the least with the highest degree of safety relative to other multi-axis fatigue evaluation criteria.Because the parameters in the Kakuno-Kawada criterion only considered the impact of torsional stress on the wheels,the evaluation results had certain limitations.In this paper,the method was modified,and the ratio of the symmetrical torsional fatigue limit to the symmetric bending fatigue limit was defined as the restrictive condition.As a result,the improved Kakuno-Kawada criterion corresponds more with the actual running force of EMU wheels with the safety factor less than the original criterion.The improved Kakuno-Kawada criterion calculation method is more safe and effective,which is conducive to ensuring the safe operation of the wheels of the EMU.