On the Applicability of Approximate Rolling and Sliding Contact Algorithms in Anisothermal Problems with Thermal Softening

Christoph Hubertus Wölfle,Ewald Werner,Christian Krempaszky

doi:10.3390/app12052549

Abstract

The residual stress approximation methods formulated by McDowell and Moyar, Jiang and Sehitoglu, and McDowell for rolling and sliding contact problems are reconsidered in the context of single anisothermal loading cycles and isotropic hardening. A consistent extention to incorporate thermal softening is developed and the generalized thermoelastoplastic algorithms are cast into a proper predictor–corrector formulation. Detailed explicit and implicit numerical integration strategies are presented and validated using specifically designed finite element models that conform to the underlying mechanical assumptions. Then, the applicability of the approximate algorithms to anisothermal problems with isotropic hardening and thermal softening is analyzed by assuming a rate-independent Johnson–Cook-type yield stress model and by comparing the obtained transient and residual stresses to results from full-scale finite element half-space models under varying loading and strain-hardening intensities. An in-depth, comparative discussion on the adequacy of the algorithms in conjunction with the justification of their respective mechanical simplifications follows. Sufficiently strong strain hardening is found to be a prerequisite for accurate predictions, and Jiang and Sehitoglu’s approach is deemed to be preferable for the considered type of problem. The conclusions drawn from the investigations are discussed in the context of common applications with particular emphasis on manufacturing process modeling and the corresponding guidelines are proposed for such use cases.

Highlights

Residual stresses often are an important factor for the fatigue life of components when dynamic thermomechanical loads have to be endured during service
Judging from the poor predictions we obtained with the McDowell and Moyar [6] (MM) assumptions for all considered hardening slopes, there seems to be little incentive to choose the hybrid scheme over the plain Jiang and Sehitoglu [7] (JS) method if sufficiently strong strain hardening behavior may be assumed
One might assume that the large overestimation of the residual stresses that we saw for the JS method in case of weak strain hardening could be shadowed by blending over to the MM assumptions for smaller hε, at least for sufficient loading and not too small hε

Summary

Introduction

Residual stresses often are an important factor for the fatigue life of components when dynamic thermomechanical loads have to be endured during service. As an important example, is widely applied for the surface finishing of metal components, and machining-induced residual stresses have been studied intensively via analytical, numerical and experimental means [1–3]. FE approaches are prohibitively expensive if real-time capability is desired e.g., for model-based manufacturing process control [4]. Given such circumstances, one might resort to simpler, semi-analytical modeling strategies. One might resort to simpler, semi-analytical modeling strategies In many cases, these revolve around modeling the actual processing by considering elastoplastic half-spaces subjected to transient surface loads, which must be appropriately abstracted from the underlying physical processes

Methods

Findings

Discussion

Conclusion