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Showing 2 results for Eftekhari Shahri
Ehsan Eftekhari Shahri, Khalili Khalili, Yosef Ahmadi Broghani,
Volume 13, Issue 13 (First Special Issue 2014)
Abstract
In tube hydroforming, the loading path, that is the relationship between axial feeding and internal fluid pressure, is of important significance. Researchers have employed various optimization approaches to find an optimum loading path. In this research a statistical method based on finite element analysis has been developed. An accurate FEA has been used to simulate the process and to find the response of the process to the loading. The Response Surface Method (RSM) has been used to model the responses from the finite element analysis. The behavior of the process can be predicted using this model. The obtained model then used to optimize the process. Since The RSM model was initially obtained for a predefined domain of variables multilevel optimization was employed to improve the accuracy of the model. The multilevel optimized curve yielded the best thickness uniformity, the result of which are reported.
Keyvan Shiri, Seyyed Ehsan Eftekhari Shahri, Habibollah Rastegari Kupaii,
Volume 22, Issue 3 (March 2022)
Abstract
Crack nucleation and propagation in engineering segments and structures are unavoidable. Replacing a damaged part is the easiest way to prevent failure, but it is not always cost-effective. Therefore, in many cases, by repairing a component, the life of defective working parts can be increased. One of the effective strategies, is mending the cracked area using composite patches witch are glued in crack formation place. The purpose of this study was to investigate the effect of patch on crack growth behavior as well as the effects of patch geometry on the mechanical properties of repaired Al5251 aluminum alloy. For this purpose, a Kevlar-epoxy composite patch with rectangular and H-shaped geometry has been used. Tensile test was performed to evaluate the mechanical properties and the crack growth behavior in the samples. The influences of patch geometry and effective area on tensile force, specimen ductility, toughness and crack forming force have been investigated. The results showed that with the use of composite patch, ductility, force at the moment of cracking and the failure force increased compared to samples without repair. Also, comparison of patches with equal effective area showed that samples repaired with H-shaped patch have more load capacity than rectangular patch. In addition, the amount of toughness in the sample repaired with H-shaped patch has increased.
