The bi-potential method has been successfully applied to the modeling of frictional contact problems in static cases. This paper presents an extension of this method for dynamic analysis of impact problems with deformable bodies. A first order algorithm is applied to the numerical integration of the time-discretized equation of motion. Using the Object-Oriented Programming (OOP) techniques in Cþþ and OpenGL graphical support, a finite element code including pre/postprocessor FER/Impact is developed. The numerical results show that, at the present stage of development, this approach is robust and efficient in terms of numerical stability and precision compared with the penalty method.

International audienceThis paper is concerned with the numerical modeling of three-dimensional unilateral contact problems in elastostatics with Coulomb friction laws. We propose a Newton-like algorithm to solve the local contact non-linear equations within the bi-potential framework. The piecewise continuous contact tangent matrices are explicitly derived. A comparative study is made between the Newton algorithm and the previously developed Uzawa algorithm. A test example is included to demonstrate the developed algorithms and to highlight their performance

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Constitutive laws are fundamental to the studies of the mechanically dominated clinical interventions involving soft biological tissues which show a highly anisotropic hyperelastic mechanical properties. The purpose of this paper was to develop an improved constitutive law based on the Holzapfel-Gasser-Ogden's model: to replace the isotropic part with Gent constitutive law so as to model the noncollagenous matrix of the media due to its generality and capability to reproduce the Neo-Hookean model. This model is implemented into an in-house finite element program. A uniaxial tension test is considered to study the influence of material parameter J(m) in Gent model and β which represents the angle between the collagen fibers and the circumferential direction. A simulation of an adventitial strip specimen under tension is performed to show the applicability of this constitutive law.