Computerized analysis of parameters affecting shape and thickness in cold rolling of strip for soft materials

A conventional 4-Hi cold rolling mill configuration was modelled and a computer program was developed to analyze the effects of inlet thickness, width, desired exit thickness, symmetric and asymmetric jack forces, screw positions, tensions on the strip, roll geometries, and material properties on strip shape and thickness. For the analysis, the finite difference method was used as the discretization technique. The roll force was obtained by integrating the calculated roll-pressure over the are of contact, and elastic distortion of rolls due to the strip interaction was also considered, For determining inter-roll force, the compatibility equation between work and backup rolls was expressed in terms of work and backup roll axis deflection and work roll surface deformation. The second compatibility equation between work roll and strip was expressed in terms of work roll axis deflections, work roll surface deformation, and estimated strip thickness. The calculated thickness distribution was used for determining shape

Application of Numerical Methods in Design and Analysis of Orthopedic Implant Integrity

In this paper a numerical analysis of hip implant model and hip implant model with a crack in a biomaterial is presented. Hip implants still exhibit problem of premature failure, promoting their integrity and life at the top of the list of problems to be solved in near future. Any damage due to wear or corrosion is ideal location for crack initiation and further fatigue growth. Therefore, this paper is focused on integrity of hip implants with an aim to improve their performance and reliability. Numerical models are based on the finite element method (FEM), including the extended FEM (X-FEM). FEM became a powerful and reliable numerical tool for analysis of structures subjected to different types of load in cases where solving of these problems was too complex for exclusively analytical methods. FEM is a method based on discretization of complex geometrical domains into much smaller and simpler ones, wherein field variables can be interpolated using shape functions. Numerical analysis was performed on three-dimensional models, to investigate mechanical behaviour of a hip implant at acting forces from 3.5 to 6.0 kN. Short theoretical background on the stress intensity factors computation is presented. Results presented in this paper indicate that acting forces can lead to implant failure due to stress field changes. For the simulation of crack propagation extended finite element method (XFEM) was used as one of the most advanced modelling techniques for this type of problem