Element Analysis Of Contact Problems Research Articles

Three-Dimensional Finite Element Analysis of Contact Problem in Dry Friction Clutches

We present an investigation through numerical analysis (FEM) of the solution of the contact problem in friction clutch systems during engagement manoeuver. The case of high contact pressure between the sliding elements of a clutch system (flywheel, friction clutch and pressure plate) has been also considered. A finite element model of a dry friction clutch system (single disc) to estimate the distributions of the contact pressure between the contact elements of the clutch system under different working conditions has been developed and the main findings are discussed. Furthermore, the effect of modules of elasticity (contact stiffness) on the distribution of contact pressure of the mating surfaces was investigated. Also, the results encompass the deformations of the contacting surfaces for different cases. This work could provide a fundamental intermediate step to obtain a partial solution to the thermos-elastic problem in order to compute the thermal-driven deformations and stresses in the automotive clutches and brakes under different working conditions.

LC-Grid: a linear global contact search algorithm for finite element analysis

The contact searching is computationally intensive and its memory requirement is highly demanding; therefore, it is significant to develop an efficient contact search algorithm with less memory required. In this paper, we propose an efficient global contact search algorithm with linear complexity in terms of computational cost and memory requirement for the finite element analysis of contact problems. This algorithm is named LC-Grid (Lei devised the algorithm and Chen implemented it). The contact space is decomposed; thereafter, all contact nodes and segments are firstly mapped onto layers, then onto rows and lastly onto cells. In each mapping level, the linked-list technique is used for the efficient storing and retrieval of contact nodes and segments. The contact detection is performed in each non-empty cell along non-empty rows in each non-empty layer, and moves to the next non-empty layer once a layer is completed. The use of migration strategy makes the algorithm insensitive to mesh size. The properties of this algorithm are investigated and numerically verified to be linearly proportional to the number of contact segments. Besides, the ideal ranges of two significant scale factors of cell size and buffer zone which strongly affect computational efficiency are determined via an illustrative example.

A finite element model for contact analysis of multiple Cosserat bodies

The objective of this paper is to develop a finite element model for multi-body contact analysis of Cosserat materials. Based on the parametric virtual work principle, a quadratic programming method is developed for finite element analysis of contact problems. The contact problem with friction between two Cosserat bodies is treated in the same way as in plastic analysis. The penalty factors, that are normally introduced into the algorithm for contact analysis, have a direct influence on accuracy of solution. There is no available rule for choosing a reasonable value of these factors for simulation of contact problems of Cosserat materials, and they are therefore cancelled through a special technique so that the numerical results can be of high accuracy. Compared with the conventional work on Cosserat elasticity, the newly developed model is on the contact analysis of the Cosserat materials and is seldom found in the existing literatures. Four examples are computed to illustrate the validity and importance of the model developed.

Boundary element analysis of contact problems using inverse techniques—linear and quadratic elements

This paper presents an inverse boundary element (BE) technique to reconstruct the boundary conditions in contact regions using photoelastic measurement data consisting of the differences of the principal stresses and their orientations at interior points. The separate individual Cartesian stress components are then obtained using the conventional ‘forward’ boundary element method (BEM). Numerical experiments show that using linear elements instead of quadratic elements can reduce the sensitivity of the inverse BEM to the errors of photoelastic measurements and gives better results. A smoothing displacement scheme is further introduced to improve the accuracy of the reconstructed tractions. When up to 5, 10 and 20 per cent random ‘noise’ was added to the simulated measurement data, the results of the inverse BE analysis still show good agreement with reference solutions. An example using real photoelastic measurements on a simple specimen is also presented and the results are found to be encouraging.

Boundary element analysis of contact problems using artificial boundary node approach

An improved version of the regular boundary element method, the artificial boundary node approach, is derived. A simple contact algorithm is designed and implemented into the direct boundary element, regular boundary element and artificial boundary node approaches. The exisiting and derived approaches are tested using some case studies. The results of the artificial boundary node approach are compared with those of the existing boundary element program, the regular element approach, ANSYS and analytical solution whenever possible. The results show the effectiveness of the artificial boundary node approach for a wider range of boundary offsets.

Finite element analysis of contact problems for a sheet metal bending process

This paper deals with the treatment of tool-work contact problems in the simulation of sheet metal bending processes using an elasto-plastic finite element method. The conditions of contract, including separation, penetration and friction, between tool and workpiece vary during the deformation process. An extended r-minimum method was employed for satisfying the above conditions. Special care was taken to treat the alteration of sticking-sliding state of friction. A special feature of this work is that a corner contact model with sliding-sticking friction is formulated in an incremental way. An approach to describe sheet sliding on a tool corner with friction is proposed and based on this approach stiffness equations and solution algorithms are introduced. These algorithms are convenient to treat the conditions of impenetrability and sliding-sticking state of friction at the corner contact interface. The contact processes of U-bending and V-bending were simulated to demonstrate applicability of the method.

A simple algorithm for three-dimensional finite element analysis of contact problems

This paper addresses the numerical solution of three-dimensional frictionless contact problems by a finite element method. The two-body contact problem is considered in the context of fully non-linear kinematics. The impenetrability constraint is satisfied via a classical penalty formulation. The contacting surfaces are discretized by means of projections of the interacting element faces onto suitably chosen flat surfaces. Attention is focused on the efficiency of the overall algorithm. Numerical simulations are conducted for a series of test problems to assess the performance of the proposed methodology.

Analysis of large deformation elastoplastic contact through finite gap elements

A finite gap element analysis of contact problems is presented in this paper. Four kinds of gap elements are established and the properties of gap elements are discussed. The formulation takes into account the nonlinearities caused by large deformation, friction and materials. Examples are given to show the validity of the technique.