Qinghua Zhou

An Efficient Numerical Method With a Parallel Computational Strategy for Solving Arbitrarily Shaped Inclusions in Elastoplastic Contact Problems

The plastic zone developed during elastoplastic contact may be effectively modeled as an inclusion in an isotropic half space. This paper proposes a simple but efficient computational method to analyze the stresses caused by near surface inclusions of arbitrary shape. The solution starts by solving a corresponding full space inclusion problem and proceeds to annul the stresses acting normal and tangential to the surface, where the numerical computations are processed by taking advantage of the fast Fourier transform techniques with a parallel computing strategy. The extreme case of a cuboidal inclusion with one facet on the surface of the half space is chosen to validate the method. When the surface truncation domain is extended sufficiently and the grids are dense enough, the results based on the new approach are in good agreement with the exact solutions. When solving a typical elastoplastic contact problem, the present analysis is roughly two times faster than the image inclusion approach and six times faster than the direct method. In addition, the present work demonstrates that a significant enhancement in the computational efficiency can be achieved through the introduction of parallel computation.

Numerical analysis of the influence of distributed inhomogeneities on tangential fretting

The tangential fretting is explored in the present study when one of the contacting bodies distributed with multiple inhomogeneities. The tangential fretting contact of an elastic sphere with an inhomogeneous material is considered. A new numerical model based on a semi-analytical method is developed by using Eshelby’s equivalent inclusion method and fast Fourier transform algorithms. The coupling between the contact loading and inhomogeneities is fully considered. The influence of multiple inhomogeneities on tangential contact is investigated. Parametric studies are conducted for the effects of randomly distributed inhomogeneities on the contact pressure, tangential displacement, subsurface stress, etc., revealing the significance of the influences of inhomogeneity distribution parameters on tangential fretting performance.

Numerical Modeling of Distributed Inhomogeneities and Their Effect on Rolling Contact Fatigue Life

This research explores the influence of distributed non-overlapping inhomogeneities on the contact properties of a material. Considered here is the half-space Hertzian contact of a sphere with an inhomogeneous material. The numerical analysis is conducted utilizing a simplified model based on Eshelby’s Equivalent Inclusion Method (EIM) and the principle of superposition. The solutions take into account interactions between all inhomogeneities. Benchmark comparisons with the results obtained with the finite element method (FEM) demonstrate the accuracy and efficiency of the proposed solution methods. The emphasis is given to a parametric study of the effect of inhomogeneities in a Gaussian distribution on material properties. Both compliant and stiff inhomogeneities are modeled. Material inhomogeneities strongly affect rolling contact fatigue (RCF) of a material, and a modified RCF life model is suggested. Homogenization and extensive numerical simulations result in semi-empirical fatigue-life reduction parameters to characterize the influence of material inhomogeneities.Copyright

Efficient numerical modeling of hertzian line contact for material with inhomogeneities

The present work proposes an efficient and general-purpose numerical approach for handling two-dimensional inhomogeneities in an elastic half plane. The inhomogeneities can be of any shape, at any location, with arbitrary material properties (which can also be non-homogeneous). To perform the numerical analysis, we first derive an explicit closed-form solution for a rectangular inclusion with uniform eigenstrain components, where the inclusion is aligned with the surface of the half plane. In view of the equivalent inclusion method, an inhomogeneity problem can be converted to a corresponding inclusion problem. In order to determine the distribution of the equivalent eigenstrain, the computational domain is meshed into rectangular elements whose resultant contributions can be efficiently computed using an efficient algorithm based on fast Fourier transform (FFT). In principle, there is no specific limitation on the type of the external load, although our major concern is the contact analysis. Parametric studies are performed and typical results highlighting the deviation of the current solution from the classical Hertzian line contact theory are presented.Copyright