摩擦系数对滚动接触疲劳裂纹萌生和磨耗影响

提出了疲劳裂纹萌生与磨耗共存发展离散化过程建模设想,根据临界平面法材料疲劳损伤理论和Archard磨耗理论,建立钢轨三维疲劳裂纹萌生与磨耗共存发展预测模型,分析轮轨接触位置的摩擦系数对曲线段钢轨表面疲劳裂纹萌生与磨耗发展的影响.结果表明,摩擦系数对接触斑面积、形状和位置无影响,但影响轮轨接触斑黏着区/滑动区的分布和切向应力状态;随着摩擦系数的增大,钢轨的平均磨耗发展率增加、磨耗量增大、裂纹萌生寿命减小,其中,摩擦系数从0.3增大至0.7时,外轨和内轨的平均磨耗发展率分别增大了约17%～55%、16%～42%,外轨和内轨的裂纹萌生寿命分别降低约24%～34%和18%～35%;随着摩擦系数的增加,外轨的裂纹萌生位置从轨面以下2.0～2.5mm处向亚表面0.9～1.0mm移动;内轨的裂纹萌生位置基本处于轨顶面下2.4～2.6 mm;轮轨接触位置的摩擦系数控制在0.3～0.4的范围,可以达到延长钢轨疲劳裂纹萌生寿命、减缓钢轨磨耗的目的.

Effects of Friction Coefficient on Rolling Contact Fatigue Crack Initiation and Wear Growth

The modeling to discrete the continuous process of the coexistence of the fatigue crack initiation and wear growth was presented. Then, a three dimensional rail model for predicting the coexistence of the fatigue crack initiation and wear was established according to the theories of critical plane fatigue damage and Archard wear. The effects of different friction coefficients between wheel and rail contact positions on fatigue crack initiation and wear growth was analyzed. Results show that the friction coefficient has a great influence on the distribution of the adhesive and slip area, and the tangential stress in wheel rail contact patch, but has little effect on the size, shape and location of the contact patch. When the friction coefficient increased, the average wear growth rate and wear amount increased while the crack initiation life reduced. For example, with the increasing of the friction coefficient from 0.3 to 0.7, the average wear growth rate of the high and low rails increased about 17%~55% and 16%~42% respectively, and crack initiation life of them decreased about 24%~34% and 18%~35% respectively. The crack initiation position in the high rail was at about 2.0~2.5 mm below the rail surface and moved upward to 0.9~1.0 mm with the increasing of the friction coefficient. And the crack initiation position in the low rail kept at about 2.4~2.6 mm below the rail surface with the increasing of the friction coefficient. It can prolong the crack initiation life and reduce the wear of the curve rails to keep the friction coefficient at 0.3~0.4 between wheel and rail contact positions.