Analysis on critical conditions of sidewall wrinkling for hydroforming of thin-walled Tee-joint |
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Affiliation: | 1. CEMMPRE, Department of Mechanical Engineering, University of Coimbra, Polo II, Rua Luís Reis Santos, Pinhal de Marrocos, 3030-788 Coimbra, Portugal;3. DGM, Institut Supérieur des Sciences Appliquées et de Technologie de Sousse, Cité Ibn Khaldoun, 4003 Sousse, Université de Sousse, Tunisia;4. CT2M, Department of Mechanical Engineering, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal;1. National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001, PR China;2. School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, PR China;1. Key Laboratory of Advanced Forging & Stamping Technology and Science, Ministry of Education of China, Yanshan University, Qinhuangdao 066004, PR China;2. College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, PR China |
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Abstract: | Based on the sidewall wrinkling phenomena in hydroforming of thin-walled Tee-joint, an analytical model for tube wrinkling under double side constraints was proposed to calculate the critical wrinkling stress. The effects of stress ratio, diameter-to-thickness ratio and tube material properties on critical condition of sidewall wrinkling were investigated. It is found that the middle of the main tube side wall is the most dangerous position for wrinkling within hydroforming of thin-walled Tee-joint. At a certain internal pressure, the critical wrinkling stress increases with increasing of ratio of hoop stress to axial stress and material strength coefficients, but decreases with increasing of work-hardening exponent and ratio of diameter to thickness. Through the analytical model combining FEM simulation, the critical wrinkling loading path according to the relation between axial feeding and internal pressure was obtained. Experimental results validates that wrinkle can be avoided if the pressure is above the critical wrinkling loading path, otherwise, wrinkle occurs. It is also verified that the analytical model of critical wrinkling stress is reasonable for the thin-walled Tee-joint hydroforming process. |
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Keywords: | Sidewall wrinkle Critical wrinkling stress Thin-walled Tee-joint Tube hydroforming Critical wrinkling loading path |
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