No abstract

This paper introduces a new technique for deep drawing of elliptic cups through a conical die without blank holder or draw beads. In this technique an elliptical-cup is produced by pushing a circular blank using a flat-headed elliptic punch through a conical die with an elliptic aperture in a single stroke. A 3D parametric finite element (FE) model was built using the commercial FEpackage ANSYS/APDL. Effects of die and punch geometry including, half-cone angle, die fillet radius, die aperture length and punch fillet radius on limiting drawing ratio (LDR), drawing load and thickness strain of the cup have been investigated. A die with half cone angle of 18° has shown the best drawability for the new technique. Finite element model results showed good agreement with experimental results. A die with an aspect ratio of 2 has been used with punches having aspect ratios ranging from 2 to 2.25. Tensile tests were carried out to obtain the stress-strain behavior for the used material. A total of seven punches were used for forming sheet metal of brass (CuZn33) with initial thicknesses of 1.5, 1.9, 2.4 and 3.2 mm at different clearance ratios (c/t). The effects of blank thickness and clearance ratio on limiting drawing ratio, drawing load and thickness strain were experimentally investigated. An elliptic cup with a limiting drawing ratio (LDR) of 2.26 has been successfully achieved.

A three-dimensional finite element analysis has been implemented to predict the transmission loss of an elliptic expansion chamber muffler for a given frequency range. Finite element models have been established by ANSYS 12.0.1. Results obtained from the model were compared with both experimental data obtained from previous work of Gerges et al. [1] . Comparison showed an excellent agreement between modeling results and experimental data. Six muffler configurations of different major/minor axis ratios of elliptic expansion chamber (a/b), with equal chamber volume have been modeled. Results demonstrated the ability of FEM to represent the acoustic attenuation performance of acoustical muffler. It also showed the effect of (a/b) ratio on the cut-off frequency due to multidimensional modes propagation. The FEM results were interpreted in various muffler configurations to determine the relationship between the number of domes in transmission loss characteristic curve and (a/b) ratio.