A Consistent Finite Element Formulation Of Nonlinear Frictional Contact Problems

A perturbed Lagrangian-based variational formulation is proposed for the finite element solution of fully nonlinear frictional contact problems. In the spirit of an operator splitting methodology, an analogy exists between the proposed treatment for the stick-slip motion and the corresponding treatment in elastoplasticity. Within the context of discrete formulations arising from a finite element approximation, explicit expressions for the frictional consistent contact tangent stiffness and residual are derived from variational equations by using a consistent linearization procedure for both the sliding and adhesion phases. The consistent tangent operator is always non-symmetric for the case of frictional sliding owing to the nature of the Coulomb's friction law employed. For two-dimensional applications, a three-node contact element is employed in the finite element discretization. Numerical examples are also presented that illustrate the performance of the proposed formulation. Keywords: structural mechanics.

This carefully edited book offers a state-of-the-art overview on formulation, mathematical analysis and numerical solution procedures of contact problems. The contributions collected in this volume summarize the lectures presented by leading scientists in the area of contact mechanics, during the 4th Contact Mechanics International Symposium (CMIS) held in Hannover, Germany, 2005.

The contact of one deformable body with another lies at the heart of almost every mechanical structure. Here, in a comprehensive treatment, two of the field's leading researchers present a systematic approach to contact problems. Using variational formulations, Kikuchi and Oden derive a multitude of new results, both for classical problems and for nonlinear problems involving large deflections and buckling of thin plates with unilateral supports, dry friction with nonclassical laws, large elastic and elastoplastic deformations with frictional contact, dynamic contacts with dynamic frictional effects, and rolling contacts. This method exposes properties of solutions obscured by classical methods, and it provides a basis for the development of powerful numerical schemes. Among the novel results presented here are algorithms for contact problems with nonlinear and nonlocal friction, and very effective algorithms for solving problems involving the large elastic deformation of hyperelastic bodies with general contact conditions. Includes detailed discussion of numerical methods for nonlinear materials with unilateral contact and friction, with examples of metalforming simulations. Also presents algorithms for the finite deformation rolling contact problem, along with a discussion of numerical examples.

Numerical methods and related computer based algorithms form the logical solution for. many complex problems encountered in science and engineering. Although numerical techniques are now well established, they have continued to expand and diversify, particularly in the fields of engineering analysis and design. Various engineering departments in the University College of Swansea, in particular, Civil, Chemical, Electrical and Computer Science, have groups working in these areas. It is from this mutual interest that the NUMETA conference series was conceived with the main objective of providing a link between engineers developing new numerical techniques and those applying them in practice. Encouraged by the success of NUMETA '85, the second conference, NUMETA '87, was held at Swansea, 6-10 July 1987. Over two hundred and twenty abstracts were submitted for consideration together with a number of invited papers from experts in the field of numerical methods. The final selection of contributed and invited papers were of a high quality and have culminated in the two volumes which form these proceedings. This volume contains papers on the themes of 'Numerical Techniques for Engineering Analysis and Design' and 'Developments in Engineering Software'. Many new developments on a wide variety of topics have been reported and these proceedings contain a wealth of information and references which we believe will be of great interest to theoreticians and practising engineers alike.

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This book introduces the key concepts of nonlinear finite element analysis procedures. The book explains the fundamental theories of the field and provides instructions on how to apply the concepts to solving practical engineering problems. Instead of covering many nonlinear problems, the book focuses on three representative problems: nonlinear elasticity, elastoplasticity, and contact problems. The book is written independent of any particular software, but tutorials and examples using four commercial programs are included as appendices: ANSYS, NASTRAN, ABAQUS, and MATLAB. In particular, the MATLAB program includes all source codes so that students can develop their own material models, or different algorithms. Please visit the author's website for supplemental material, including PowerPoint presentations and MATLAB codes, at http://www2.mae.ufl.edu/nkim/INFEM/

Dynamic contact problems play an important role in dictating the integrity, performance and safety of many engineering systems/components involved in vehicle design, armament and ballistics, metal forming/cutting, and surface treatments, just to name a few. Despite their importance to the mechanical integrity of the systems examined, dynamic contact effects are frequently treated using oversimplifying assumptions, which neglect the main feature of the problem. This is because of the complexity of the governing system of equations. In this work, dynamic frictional contact problems are formulated using the more reliable and consistent variational inequalities (VI) approach. Three aspects of the problem are accordingly examined. The first is concerned with the development of the appropriate variational inequality formulations and solution strategies for dynamic frictional contact problems involving material and geometrical nonlinearity. Two models of surfaces are taken into account: (i) perfectly smooth surfaces, and (ii) more realistic surfaces, which take into account the change in compliance due to surface roughness. A new technique for representing the kinematic contact conditions is developed. Two newly devised numerical procedures are devised to solve the general dynamic frictional contact problem for elastic and elasto-plastic media. The first solution strategy, which regularises friction, is based upon the iterative use of mathematical programming and Lagrange multipliers. The second approach is accomplished using a nondifferentiable optimisation algorithm, through a sequence of mathematical programming sub-problems. The second aspect of the work is concerned with the selection of a suitable time integration scheme for contact problems. The values of the time integration parameters are so chosen to ensure that the solution is second order accurate, unconditionally stable, preserves energy and momentum during rigid impact, thus minimising numerical oscillations and ensuring optimal numerical dissipation. Finally, the developed algorithms are validated and applied to the analysis of several interesting engineering problems. The numerical predictions are compared to existing experiments as well as a commercial finite element code. The results reveal that the new dynamic friction contact formulations are more accurate than the traditional variational methods. These newly developed algorithms should provide designers with a powerful tool for treating dynamic elasto-plastic problems involving frictional contact.

Nonlinear Finite Elements for Continua and Structures p>Nonlinear Finite Elements for Continua and Structures This updated and expanded edition of the bestselling textbook provides a comprehensive introduction to the methods and theory of nonlinear finite element analysis. New material provides a concise introduction to some of the cutting-edge methods that have evolved in recent years in the field of nonlinear finite element modeling, and includes the eXtended Finite Element Method (XFEM), multiresolution continuum theory for multiscale microstructures, and dislocation- density-based crystalline plasticity. Nonlinear Finite Elements for Continua and Structures, Second Edition focuses on the formulation and solution of discrete equations for various classes of problems that are of principal interest in applications to solid and structural mechanics. Topics covered include the discretization by finite elements of continua in one dimension and in multi-dimensions; the formulation of constitutive equations for nonlinear materials and large deformations; procedures for the solution of the discrete equations, including considerations of both numerical and multiscale physical instabilities; and the treatment of structural and contact-impact problems. Key features: Presents a detailed and rigorous treatment of nonlinear solid mechanics and how it can be implemented in finite element analysis Covers many of the material laws used in today’s software and research Introduces advanced topics in nonlinear finite element modelling of continua Introduction of multiresolution continuum theory and XFEM Accompanied by a website hosting a solution manual and MATLAB® and FORTRAN code Nonlinear Finite Elements for Continua and Structures, Second Edition is a must-have textbook for graduate students in mechanical engineering, civil engineering, applied mathematics, engineering mechanics, and materials science, and is also an excellent source of information for researchers and practitioners.

Finite Element Methods are used for numerous engineering applications where numerical solutions of partial differential equations are needed. As computers can now deal with the millions of parameters used in these methods, automatic error estimation and automatic adaptation of the utilised method (according to this error estimation), has become a hot research topic. This text offers comprehensive coverage of this new field of automatic adaptation and error estimation, bringing together the work of eight outstanding researchers in this field who have completed a six year national research project within the German Science Foundation. The result is a state-of-the-art work in true reference style. Each chapter is self-contained and covers theoretical, algorithmic and software presentations as well as solved problems. A main feature consists of several carefully elaborated benchmarks of 2D- and 3D- applications. * First book to go beyond the Finite Element Method in itself * Covers material from a new research area * Presents benchmarks of 2D- and 3D- applications * Fits with the new trend for genetic strategies in engineering