Rolling Contact Analysis Research Articles

A boundary element approach for rolling contact of viscoelastic bodies with friction

A boundary element method (BEM) approach for the steady-state rolling contact of viscoelastic solids is presented. The friction is finite and Coulomb's law is used. By applying the correspondence principle of linear viscoelasticity, the fundamental solutions for an isotropic viscoelastic medium are obtained, which are referred to a Eulerian coordinate system attached to the moving unit load. To adapt the viscoelastic constitutive relation to an elastic contact BEM-mathematical programming algorithm, the main modification is to replace the elastic fundamental solutions with these viscoelastic counterparts. The contact between a (visco)elastic body and an elastic one covered by a thin viscoelastic boundary film is also studied. This kind of problem is of particular importance in practical applications, such as the numerical simulation of self-lubricating polymer transfer film. It is required to find the (visco)elastic field in the film and the bulk body underneath, and compare it to the result for the case of direct contact without the film. The polymer film is modeled by parallel compressive elements, and a pure rolling contact analysis is carried out. The resulting BEM-mathematical programming formulation does not satisfy the classical complementarity condition and a special algorithm to determine the contact state is given.

Elastic-Plastic Analysis of Rolling Contact for Suaface Hardened Steel.

This paper presents the study of the effect of surface hardening treatment on the wear characteristics of the hardened steel for rolling contact problem. The surface hardened steels have been studied in many papers, but the analysis that treated rolling-sliding contact with FEM is scarcely found. The wear characteristics of the contact surfaces during rolling and sliding should be predicted precisely. We have calculated the deformation, equivalent plastic strain, residual stress, and shear stress-strain curve at the treated area of the steel. It is found that the deformation of treated steel is smaller than that of not-treated steel. And it is the same as in the case where the friction force exists.

An Analytical Approach to Elastic-Plastic Stress Analysis of Rolling Contact

Based on a stress invariant hypothesis and a stress/strain relaxation procedure, an analytical approach is forwarded for approximate determination of residual stresses and strain accumulation in elastic-plastic stress analysis of rolling contact. For line rolling contact problems, the proposed method produces residual stress distributions in favorable agreement with the existing finite element findings. It constitutes a significant improvement over the Merwin-Johnson and the McDowell-Moyar methods established earlier. The proposed approach is employed to study combined rolling and sliding for selected materials, with special attention devoted to 1070 steel behavior. Normal load determines the subsurface residual stresses and the size of the subsurface plastic zone. On the other hand, the influence of tangential force penetrates to a depth of 0.3a, where a is the half width of the contact area, and has diminishing influence on the residual stresses beyond this thin layer. A two-surface plasticity model, commensurate with nonlinear kinematic hardening, is utilized in solution of incremental surface displacements with repeated rolling. It is demonstrated that a driven wheel undergoes greater plastic deformation than the driving wheel, suggesting that the driven wheel experiences enhanced fatigue damage. Furthermore, the calculated residual stresses are compared with the existing experimental data from the literature with exceptional agreements.

Analysis of the effects of rigid and elastic boundary conditions in the elastic-plastic finite element analysis of rolling contact

The effects of boundary conditions and mesh refinement of finite element models of elasto-plastic 2-dimensional pure rolling contact are examined. The pure rolling of a cylinder is simulated by incrementally translating a semi-elliptical Hertzian pressure distribution over a finite element model of a semi-infinite half space. The half space is treated as an elastic-linear-kinematic-hardening-plastic (ELKP) material. The calculations evaluate the effects of rigid and elastic boundary conditions and two degrees of mesh refinement on the steady state residual stresses, the continuing cyclic plasticity, and the residual displacements. The results show that the boundary conditions influence the circumferential residual stresses and residual displacements, while they do not affect the axial residual stresses and the continuing cyclic plasticity. Careful choice of mesh refinement is shown to improve results and decrease computation time.

Analysis of rolling contact with kinematic hardening for rail steel properties

This study presents calculations of two-dimensional rolling contact deformation for rail steel properties. Finite element analyses, previously carried out for perfect plasticity, are extended to the kinematic hardening behavior of rail steel. A three-parameter elastic-linear-kinematic-hardeningplastic description of the cyclic stress-strain behavior of rail steel is inserted in the finite element model. Steady state results are obtained after two translations. The effects of the kinematic hardening at three relative peak pressures p o k k = 4.0, 4.5 and 5.0 are examined. The calculations evaluate the rim distortion, the cyclic plastic strains and the residual stresses, the shakedown limit for kinematic hardening and the effects of strain-amplitudedependent kinematic properties. The calculations reveal that the kinematic hardening of rail steel produces substantial alterations relative to the deformation and residual stresses associated with perfect plasticity. Cyclic strains are an order of magnitude smaller and the residual stresses are about half the value of comparable relative contact pressures. While the relative elastic shakedown limit, p o k k = 4 , is the same as for perfect plasticity, absolute values of wheel load at shakedown are modest because of the relatively low value of the kinematic yield strength of rail steel. Accordingly, a 33000 lbf (146.7 KN) wheel load applied to a new rail produces a relative peak contact pressure p o k k = 6.2 which exceeds the corresponding shakedown limit.