An analysis of drawbead restraining force in the stamping process

A theoretical model based on the virtual work principle was proposed to calculate the restraining force produced by the drawbead located on a stamping die surface. In the theoretical model the deformation of the sheet metal drawn over the groove shoulder or bead is assumed to be subjected to bending, sliding and unbending processes, and only the sliding process is responsible for the frictional force. The governing equations derived from the theoretical model were solved by a numerical procedure. In order to validate the proposed model, the finite element simulations were also performed to calculate the drawbead restraining forces for various steels. The simulated results together with the experimental data obtained from the published literature were compared with the predicted values calculated by using the numerical procedure. The good agreement between the simulated results, experimental data and the calculated values justifies the proposed theoretical model.     

Transient diffusion through a porous plate between two compartments

Abstract

A general model describing transient diffusion through a porous or perforated plate between two compartments of changing concentrations is proposed. The equations derived from this model can be used to evaluate the effective diffusivity of a diffusing species in a porous material and the molecular diffusivity in a liquid phase. Several charts plotted from solutions to these equations are also presented for determination of diffusivity.     

A global optimization technique to identify overall transformation kinetics using dilatometry data—applications to austenitization of steels

This paper presents the development of a new algorithm that is able to accurately identify the overall kinetics of diffusional phase transformations, including austenitization from dilatometry data. Such algorithm is useful in the study of the role of microstructural features in the kinetics of austenitization. Specifically, the fundamental parameters governing the nucleation and growth of the new phase in diffusional transformations are determined by minimizing the error between the measured dilatometry curves and that calculated by the pre-specified kinetic model. In the process, the progress of transformation in the particular dilatometry tests can also be determined simultaneously. The accuracy and applicability of the developed algorithm is demonstrated by using the dilatometry data of AISI 1080 steel in austenitization as well as several hypothetical transformations. A TTT diagram of austenitization of AISI 1080 is generated.     

Stress analysis in solidification processes: Application to continuous casting

Calculations of thermal stresses in solidifying materials have been carried out using thermal-elastoplastic finite element method. The temperature history in the process of solidification was calculated first by the temperature recovery method and then transferred to the MARC code for the stress analysis. The scheme was applied to a complete analysis of continuous casting of low carbon steel. According to the two-dimensional model, the predicted depth of the liquid pool showed good agreement with experimental measurement. The analysis results were compiled into temperature history, shell thickness, stress history, principal stress distributions, residual stresses and deformation.