Modeling and Experimental Validation of the Effect of Sand Filling on Avoiding Wrinkling Phenomenon in Thin-Walled Tube Bending Process

This paper investigates a method to avoid the wrinkling in thin-walled tubes in bending process. In the tube bending process there are several effective parameters such as wall thickness, outer diameter-to-wall thickness ratio, centerline bending radius-to-outer diameter ratio. Any mismatch in the selection of the process parameters would cause defects like wrinkling, serve changes in wall thickness, and cross section distortion. For example, the depth of wrinkling increases with reduction in wall thickness and outer diameter-to-wall thickness ratio for a certain bending angle and radius. In this research, to avoid wrinkle initiation, tube is filled by sand and then bended. This sandy core is supported the tube from inner, and tube is prepared to bending. After bending process, sand is removed. In this work, to study the process numerically, a 3D finite element model of the horizontal bending process is built using ANSYS software. Then, experimental tests have been carried out to verify the simulation results and are developed to provide additional insight. A comparison between numerical and experimental results shows a reasonable agreement. It shows that wrinkle initiation can be avoided with filler material like sand.