Mechanical Reaction of Granular Filler and Its Interaction Mechanism with Tube During Push-Bending Process

In newly developed tube bending process, fillers are generally used to introduce internal pressure in active or passive way, which can reduce the risk of wrinkling and collapse at the outer and inner wall of tube, respectively. Therefore, it is of great significance to study the internal pressure distribution provided by fillers in tube bending process. In this paper, the mechanical reaction of granular filler and its interaction mechanism with tube during the granular media filler assisted push-bending (GMF-PB) process were studied. Based on the theory of discrete element method (DEM), the discrete element model of the bending of granular filler was established. The discrete distribution of contact force at the interface between granular filler and bending tube was obtained, then equivalent contact pressure can be calculated by using equivalent pressure model. The influencing factors for the distribution of internal pressure of the granular filler were investigated. The interaction mechanism between internal pressure distribution of granular filler and wrinkling and collapse of tube during GMF-PB process was explored. This paper provides a reliable foundation for analyzing the influence of mechanical reaction of granular filler on the wrinkling defects of bent tubes.