The tube bending process is one of the most important metal forming methods used in various industries such as automotive, oil an‎d gas, fluid transport, an‎d thermal systems. One of the major challenges in this process is the occurrence of wrinkling on the inner radius of the bend, which can lead to quality degradation, reduced mechanical strength, an‎d localized failure of the tube. Therefore, accurately identifying the conditions that cause wrinkling an‎d predicting the forming limit in this process is of great importance. In this study, an analytical model based on energy theory has been developed to predict wrinkling in thin-walled tube bending. By applying the principle of energy balance between internal energy an‎d the work of external forces, a criterion for the onset of wrinkling has been derived. To model the wrinkling phenomenon, various wave functions with oscillatory behavior have been defined an‎d eva‎luated. To enhance accuracy, different boundary conditions an‎d the effects of parameters such as bend radius, tube thickness, presence of a man‎drel, an‎d mechanical properties have been incorporated into the model. The analysis process includes four distinct approaches: initial analysis, direct bending analysis, combined analysis, an‎d polynomial relation analysis. In each approach, Mathcad Prime 10 an‎d Excel software were used to solve the equations, an‎d the model’s accuracy was assessed by comparing the results with experimental data an‎d findings from previous studies. The results show that the new wave function with modified coefficients an‎d a gentle slope aligns well with the actual behavior of bent tubes. Additionally, incorporating geometric parameters such as cross-sectional distortion improved prediction accuracy in the combined models. This research offers a simple, accurate, an‎d adaptable model for predicting wrinkling, which can play an effective role in the industrial design of bending processes an‎d the optimization of their parameters.

مهران مرادي غريبوند

محمدرضا فروزان , مهدي سلماني تهراني