Effect of pipe bending by rotary tube bending process on durability of frame structure

For Original Equipment Manufacturers (OEMs), ensuring the overall quality of two-wheeler frames hinges on robust process capability and meticulous design considerations. A comprehensive Computer-Aided Engineering (CAE) simulation approach, integrating manufacturing processes and design elements, is vital for achieving optimal durability. This study focuses on developing such an approach through detailed finite element analysis of Cold Electric Welded (CEW) annealed round pipes used in frame construction. We simulate the bending process, capturing structural deformation and residual stresses. A 3D mechanical model with realistic tooling geometries and contact interactions accurately represents shape changes, ovality, and wall thickness redistribution. Unlike Electric Resistance Welded (ERW) pipes, CEW pipes, due to annealing, offer a stress-free initial state, allowing precise deformation analysis. Simulation results demonstrate significant geometric alterations in the bend zone, including changes in ovality and wall thickness, impacted by bend radius and angle. Residual stress analysis reveals a combination of tensile and compressive stresses affecting structural integrity. These deformations can cause weld fit-up issues, altered section modulus, and irregular weld profiles, compromising weld joint performance. To mitigate these risks, we employ a conservative fatigue analysis in weld fatigue life calculation tool; FE-Safe, using lower bound weld material properties to account for potential bending-induced imperfections. This research aims to enhance the reliability and efficiency of two-wheeler trellis frames by improving fatigue simulation accuracy. The insights gained can be used for bending process optimization, weld joint design refinement, and the development of robust frame structures.