The Research Of The Wheel And Rail Adhesion Problem

Adhesion problem of contact wheel and rail is essentially rolling friction problem, the max longitudinal friction by influence of many cases. Locomotive wheels are disturbed randomly, when the locomotive though straight, turnout, curve, slope, tunnel, rail with slag and without etc. the max longitudinal friction (adhesion force) constantly changing, so locomotive adhesion problem is very complex.According to the lateral displacement of wheels, the seven models of contact wheel and rail are built and the material model of elastic-plastic is chosen. The angle of tangential force and rails longitudinal direction is bigger, more disadvantageous to improve adhesion. According to the tangential force direction, contact spot can be divided into two areas, one is the angel of tangential force and rails longitudinal direction is smaller and the tangential force is bigger near adhesion zone; the other is the angel is bigger and the value of tangential force is not equal.The five models of contact wheel and rail are established so as to the contact angel of outer wheel and rail is constantly changing during the locomotive through curve. The contact spot area between wheel and rail with contact angle increases and decreases; when the contact angle is smaller, adhesive coefficient decreases with increasing of lateral force. Adhesion coefficient increases and decreases with increasing of lateral force under of the larger contact angle.The coulomb friction law has been adopted in calculation of wheel-rail rolling friction, but a large number of engineering experiments proof that it has certain limitation, do not suit calculation of wheel-rail rolling friction. For solving this problem, this paper use of data of static adhesion test, combined with the calculation of wheel-rail rolling friction and find the relationship between these factors and adhesion coefficient, the function express of adhesion coefficient will create eventually.The models of contact wheel and rail are established through parameter variable principle and mathematical quadratic programming, analyzing tangential force, contact angle of wheel-rail, and lateral load on adhesion effects, the ratio of adhesion and adhesion control are improved as theoretical basis. The function of adhesion coefficient which fits computation of contact wheel and rail was created for solving the limitations of the coulomb's law of friction.