Yu.A. Goritskiy¹, D.G. Tigetov¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.14, No.4, pp. 99-102, 2010, DOI:10.3970/icces.2010.014.099

Abstract It is well-known that process of friction depends immensely on the surface roughness. Also, surfaces change while in friction. Roughness change is influenced by many factors such as shape of asperities, physical characteristics of materials, load, sliding velocity, lubricant and others. It was shown experimentally that roughness reaches a steady form (known as ``equilibrium roughness'') while running-in process. It is ``equilibrium roughness'' that determines a stationary friction mode. More >

S. Hartmann¹, R. Weyler², J. Oliver¹, J.C. Cante², J.A. Hernández¹

CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.3, pp. 211-270, 2010, DOI:10.3970/cmes.2010.055.211

Abstract This work describes a three-dimensional contact domain method for large deformation frictionless contact problems. Theoretical basis and numerical aspects of this specific contact method are given in [Oliver, Hartmann, Cante, Weyler and Hernández (2009)] and [Hartmann, Oliver, Weyler, Cante and Hernández (2009)] for two-dimensional, large deformation frictional contact problems. In this method, in contrast to many other contact formulations, the necessary contact constraints are formulated on a so-called contact domain, which can be interpreted as a fictive intermediate region connecting the potential contact surfaces of the deformable bodies. This contact domain has the same dimension More >

Chih-Wei Hsieh¹, Chien-Li Wu¹, Cheng-Kuo Sung^1,2

The International Conference on Computational & Experimental Engineering and Sciences, Vol.13, No.2, pp. 33-34, 2009, DOI:10.3970/icces.2009.013.033

Abstract Molecular dynamics (MD) simulation has been demonstrated as a promising method to analyze formation and friction mechanisms of the nanoimprint process. Especially, it provides a useful tool for investigating critical issues that are generally difficult to be examined by the experiment because of cross talks among influential factors or attainability of direct measurement. This study utilized the friction mechanism to explore the factors that would affect the quality of mold replication in the direct nanoimprint. Those factors included mechanical properties of thin films, interaction force between mold and thin-film materials, and surface roughness of the… More >

Emil Budescu¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.11, No.1, pp. 17-18, 2009, DOI:10.3970/icces.2009.011.017

Abstract For the visco-plastic materials of type Bingham fluid, like granular materials, the process of flow begins when the force F^ˉ, which variation is presented in figure 1, reaches the minimum value of shearing limit. More >

En-Cheng Liu¹, Syh-Tsang Jenq^1,2, Shih-Wei Kung³, Chie Gau¹, Hsin-Luen Tsai⁴, Cheng-Ching Lee⁵, Yu-Der Chen⁵

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.4, pp. 245-246, 2009, DOI:10.3970/icces.2009.009.245

Abstract The purpose of the present work is to study the disc brake squeal problem for passenger cars in order to reduce the instable high frequency squeal modes. The ABAQUS/Standard implicit method was used to perform dynamic contact vibration analysis of the current disc brake finite element model. The disc brake system studied here contains the caliper, bracket, brake disc, and brake pad. Notice that brake pad in general contains both brake lining and brake shoe. The brake pad with a specific chamfer pattern and the brake disc with a series of cooling ribs for ventilation… More >

H. T. Xiao¹, Z. Q. Yue²

CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.2, pp. 159-180, 2009, DOI:10.3970/cmes.2009.052.159

Abstract This paper presents a three-dimensional boundary element method for contact problems of an elastic indenter on the surface of functionally graded materials (FGMs). The FGM elastic properties can have any irregular variations with depth. The indenter is subjected to the loading normal to the flat contact surface. The classical Kelvin solution is used for the mathematical formulation of the homogeneous elastic indenter. The generalized Kelvin solution is used for the mathematical formulation of the FGM base. The contact variables are defined with respect to each of the surfaces using local coordinate systems. The corresponding contact More >

Peter J. Ireman, Anders Klarbring¹, Niclas Strömberg

CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.2, pp. 125-158, 2009, DOI:10.3970/cmes.2009.052.125

Abstract In this paper finite element approaches for fretting fatigue are proposed on the basis of a non-local model of continuum damage coupled to friction and wear. The model is formulated in the frame-work of a standard material. In a previous paper this was done in the spirit of Maugin, where an extra entropy flux is introduced in the second law in order to include the gradient of the internal variable in a proper manner. In this paper we follow instead the ideas of Frémond and others, where this extra entropy flux is no longer needed,… More >

A. Colombo¹, U. Galvanetto²

CMES-Computer Modeling in Engineering & Sciences, Vol.53, No.3, pp. 235-254, 2009, DOI:10.3970/cmes.2009.053.235

Abstract The paper addresses the problem of computing the stable manifolds of equilibria and limit cycles of saddle type in piecewise smooth dynamical systems. All singular points that are generically present along one-dimensional or two-dimensional manifolds are classified and such a classification is then used to define a method for the numerical computation of the stable manifolds. Finally the proposed method is applied to the case of a stick-slip oscillator. More >

S. Tangaramvong, F. Tin-Loi

CMES-Computer Modeling in Engineering & Sciences, Vol.49, No.3, pp. 269-296, 2009, DOI:10.3970/cmes.2009.049.269

Abstract We consider the optimal synthesis, namely minimum weight design, of rigid perfectly-plastic structures for which some supports involve unilateral frictional contact. This problem is of interest as it is not only encountered in practice but it also involves, in the general friction case, a nonassociative complementarity condition that makes it theoretically and numerically challenging. For simplicity of exposition, we focus on the class of bar structures for which yielding is governed by either pure bending or by combined axial and flexural forces. In view of possible multiplicity of solutions due to nonassociativity, a direct optimization More >

K.Willner ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.48, No.3, pp. 303-336, 2009, DOI:10.3970/cmes.2009.048.303

Abstract The dynamic behavior of structures with joints is strongly influenced by the constitutive behavior within the contact areas. In this paper the influence of an elaborate constitutive contact model based on a rough surface model is investigated. The contact model is able to describe several effects like pressure dependent contact stiffness in normal and tangential direction as well as microslip effects. The corresponding constitutive contact laws are implemented in a finite element code. Numerical simulations are compared to experimental results of a clamped double-beam experiment. More >