Buckling behavior of AA6061 circular tube under axial compression by considering contact condition of tube end

Abstract

When a circular tube is under axial compression, it can be developed into specific forming technologies (e.g., tube inversion). However buckling failure is prone to occurring and seriously restricts the successful realization of the forming process or service performance. In this paper the conical convex or concave dies with different semi-cone angles were adopted to change tube end contact conditions and the buckling process, critical buckling force and the buckling waves of AA6061 tube under axial compression were investigated by using finite element simulation combined with experiments. The results show that the buckling deformation, the position where initial buckling wave appears, and the distribution of axial stress in tube blank are quite different when axially compressed on a flat die or a conical convex die (semi-cone angle β = 60°). For the conical convex dies as semi-cone angle increases from 75° to 87.5°, or for concave dies as semi-cone angle decreases from 110° to 92.5°, the axial compressive stress, critical buckling force and critical reduction increase, while the peak of the buckled wave decreases, i.e., occurrence of buckling delays and the buckling becomes more difficult to occur. When β is 90° (flat die), the critical buckling force and reduction reach the peak values.

Keywords

• AA6061 tube
• Conical die
• Axial compression
• Buckling failure
• Contact condition