剥离掉块对轮轨滑动接触热弹塑性的影响
Effects of spallation on rail thermo-elasto-plasticity in wheel-rail sliding contact

利用有限元软件ANSYS建立了钢轨轨面剥离掉块伤损条件下的轮轨滑动接触有限元模型,考虑了轮轨材料的非线性影响,计算了车轮经过剥离掉块凹坑时的轮轨接触冲击行为,并采用瞬态分析方法研究了不同剥离掉块伤损长度、深度、摩擦因数与轮轨间相对滑动速度对钢轨剥离掉块伤损区域热弹塑性的影响。分析结果表明:在剥离掉块伤损区域长度为2 cm、深度为4 mm时,钢轨等效塑性应变最大,且伤损区域后侧的值为前侧的3～4倍; 在剥离掉块伤损区域长度为2 cm、深度为6 mm时,塑性变形最大,且伤损区域后侧的值约为前侧的2倍; 轮轨接触应力随摩擦因数的增大而减小,钢轨的摩擦温升、等效塑性应变、塑性变形、等效应力与纵向剪切应力均随随摩擦因数的增大而增大,当摩擦因数大于0.3时,等效应力和纵向剪切应力的增长速率变缓; 当相对滑动速度等于3 m？s-1或大于等于6 m？s-1时,钢轨的受力、变形和温升最不利。
A finite element model with rail spallations in wheel-rail sliding contact was established by using the finite element software ANSYS, the material nonlinearity was considered, the impact behaviors of wheel-rail contact were calculated when the wheels passed through the rail spallations, and the influences of length and depth of rail spalling area, friction coefficient and sliding speed on the thermo-elasto-plasticity of rail spalling area were analyzed by transient analysis. Analysis result shows when the length of spalling area is 2 cm and the depth is 4 mm, the equivalent plastic strain of rail reaches to the maximum, and the value in the rear of spalling area is 3-4 times as large as the value in the front. When the length of spalling area is 2 cm and the depth is 6 mm, the plastic deformation reaches to the maximum, and the value in the rear is about twice as large as the value in the front. The contact stress reduces with the increase of friction coefficient, while the frictional rising temperature, equivalent plastic strain, plastic deformation, equivalent stress and longitudinal shear stress of rail increase. When the friction coefficient is bigger than 0.3, the growth of equivalent stress and longitudinal shear stress becomes slower as the increase of fraction coefficient. When the sliding speed is equal to 3 m？s-1, or is not less than 6 m？s-1, the stress, deformation and temperature of rail are in most unfavorable conditions. 1 tab, 22 figs, 23 refs