Three-Dimensional Elastic Bodies in Rolling Contact

Development of an innovative wheel–rail contact model for the analysis of degraded adhesion in railway systems

“…(1)) predicted by the Kalker and Polach theories [1,6,9] and in agreement with the experimental results (linearly increasing for small creepage and asymptotically decreasing for large creepage); see for instance Fig. 2b.…”

“…Finally, it has to be noticed that the semi-axes a and b of the contact patch (see Eq. (6)) depend only on the normal force N c , the material properties (the Young modulus E, the shear modulus G and the Poisson coefficient s) and the contact point position P c on wheel and rail (through the curvatures of the contact surfaces in the contact point) while the contact shear stiffness C (N/m 3 ) is a function only of the semi-axes a and b and of the material properties [9]. In this simple 1D case Eq.…”

“…where c 11 ¼c 11 (s,a/b) is the Kalker coefficient [9]. At this first step of the model development, the contact point position P c (single contact) is supposed to be known and nearly constant; in particular the wheel and rail profiles and the laying angle α p are known, while the wheelset is supposed to be placed in its centred position (see the next sections for further details).…”

“…In this research activity the two main adhesion coefficients f d and f r (degraded adhesion and adhesion recovery) have been calculated according to Polach [1,6,9]:…”

“…This kind of models necessarily represents a trade-off between accuracy and numerical efficiency and consists of three fundamental logical steps: the detection of the contact point positions [2,7,8,[3][4][5], the calculation of the normal contact forces (based on the improvements of the Hertz theory [9,3,4,5]) and the evaluation of the tangential contact forces (mainly based on the Kalker theory [9] and the Polach one [1,6]). …”