Filler parameters affected wrinkling behavior of aluminum alloy double-layered gap tube in rotary draw bending process

During the rotary draw bending process of aluminum alloy double-layered gap tube, filler needs to be added in the gap between inner and outer tubes. Different filler materials and the parameters of the filler, however, have a significant and complicated influence on the wrinkling of inner and outer tubes. Thus, a 3D finite element (FE) model for the rotary draw bending of aluminum alloy double-layered gap tube with different polymer materials as the fillers was established and validated based on the ABAQUS platform. By using the built model, the effects of different filler materials with the typical mechanical properties and the key parameters on the wrinkling behavior of the double-layered gap tube were investigated. The results show that the polymethylmethacrylate (PMMA) and polyvinyl chloride (PVC) used as the hard and tough fillers have an obvious inhibition effect on wrinkling than soft and tough filler polytetrafluoroethylene (PTFE). Decreasing in the assembly clearance and increasing in the thickness ratio h/t can effectively reduce wrinkling degree, while the wrinkling is generally decreased first and then increased with the increasing friction coefficient, and reaches the minimum value when the friction coefficient is 0.12.