轮轨的相互作用实际上是反复荷载作用下的接触应力问题。只有运用塑性理论的安定性分析才能找到合理的强度判据。本文在论述轮轨接触应力的Hertz弹性解后,根据Melan定理进行了安定性分析,并提出了轮轨强度设计的新判据,即(τ_(xz)~2+τ_(yz)~2)_(max)≤k~2。结果表明,新判据大大地提高了根据弹性解所确定的最大轴重。算例指出,最大轴重比弹性解提高64％左右。 Wheel-rail interaction is actually a contact stress problem under repeated load. Only by using the stability analysis of plasticity theory can we find the reasonable strength criterion. After discussing the Hertz elastic solution of the wheel-rail contact stress, the stability analysis based on the Melan’s theorem is carried out. A new criterion for the design of the wheel-rail strength is proposed, namely (τ_ (xz) ~ 2 + τ_ (yz) ~ 2) _ (max) ≤k ~ 2. The results show that the new criterion greatly enhances the maximum axle load determined by elastic solution. The example shows that the maximum axial weight is about 64% higher than the elastic solution.