A nonlinear vehicle-structure interaction methodology with wheel-rail detachment and reattachment

. A vehicle-structure interaction methodology with a nonlinear contact formulation
based on contact and target elements has been developed. To solve the dynamic equations of
motion, an incremental formulation has been used due to the nonlinear nature of the contact
mechanics, while a procedure based on the Lagrange multiplier method imposes the contact
constraint equations when contact occurs. The system of nonlinear equations is solved by an
efficient block factorization solver that reorders the system matrix and isolates the nonlinear
terms that belong to the contact elements or to other nonlinear elements that may be incorporated
in the model. Such procedure avoids multiple unnecessary factorizations of the linear
terms during each Newton iteration, making the formulation efficient and computationally
attractive. A numerical example has been carried out to validate the accuracy and efficiency
of the present methodology. The obtained results have shown a good agreement with the results
obtained with the commercial finite element software ANSYS