Application of a new integrated optimization approach in sheet hydroforming process

The purpose of this study is to produce a desired hydroformed product under the optimal pressure profile. To achieve this purpose, a new adaptive optimization approach is proposed based on fuzzy logic control (FLC) integrated with simulated annealing (SA) optimization technique and ANSYS parametric design language (APDL). An intermediate MATLAB code was developed and used to manage data transfer automatically between FLC, SA and APDL, in which there would be no need for any interaction of user/designer during the optimization process execution. This method aims to find the optimal pressure loading profile, prevent wrinkling and necking failures, reduce unsuccessful iterations, and enhance convergence precision. This method is capable of adaptively changing the process parameters in order to reach the optimized values with higher accuracy in a more reasonable time. The results show a good agreement between the proposed optimization approach and experiments. The developed optimization approach is a practical and reliable design tool for industrial production of any symmetric shell cups using hydroforming process

Study the effect of Gaussian and Uniform heat flux on laser forming of Bi-layer sheets

Laser forming process is one of the newest methods of sheet metal bending which no mechanical force needs. Although lots of investigations on laser forming process of mono layer sheet metals have been done, any experiments have not been conducted around bi- layer sheets. In this paper, laser forming process of bi-layer Al/SiC work pieces under Gaussian and Uniform heat distribution has been studied. Elastic- plastic temperature dependent material properties are considered. Also, the boundary condition is applied as free heat convection. The results of numerical simulations revealed that the amount of bending angle in Uniform heat flux distribution is always further than Gaussian distribution. In addition, temperature distribution diagram in Uniform heat flux is almost 5% further than Gaussian form, and the maximum temperature in the work piece is 6% larger. For validation of numerical analyses, experimental tests are done by an Nd: YAG laser on bi-layer Fe/Al sheets. The amounts of bending angles are so close to the results of simulation. The average of the bending angle is almost derived 0.0038 Degree/ Watt in these experimental tests

Effect of multi-pass friction stir processing on thermal distribution and mechanical properties of AZ91

In this paper, the effect of multi-pass friction stir processing on mechanical properties of AZ91 alloy has been studied. For this purpose, the microhardness, tensile, and creep tests were conducted at several temperatures. Optical microscopy and scanning electron micrograph were used to study the microstructure of the processed samples. The experimental results indicated that at room temperature, the microhardness, tensile, and creep strength of the processed samples as compared to the unprocessed ones increased by 23%, 29%, and 38%, respectively. Also, after friction stir processing, the tensile and creep strength of the samples at 210 °C increased by 31% and 47%. In addition, a three-dimensional model was developed to simulate two-pass friction stir processing using ABAQUS/Explicit software. This model involved the Johnson-Cook models for defining material behavior during the process and identifying the fracture criterion. To control the mesh distortion during consecutive passes, the Arbitrary Lagrangian-Eulerian technique was used. Using the developed model, the peak temperature, thermal distribution, and residual stress field during multi-pass friction stir processing on AZ91 have been studied. The empirical results indicated the beneficial influence of the multi-pass friction stir processing on the microstructure and high-temperature mechanical properties of AZ91 alloy