A study on plastic wrinkling in thin-walled tube bending via an energy-based wrinkling prediction model

Abstract

Thin-walled tube bending is an advanced technology for producing precision bent tube parts in aerospace, aviation and automobiles, etc. With increasing demands of bending tubes with a larger tube diameter and a smaller bending radius, wrinkling instability is a critical issue to be solved urgently for improving the bending limit and forming quality in this process. In this study, by using the energy principle, combined with analytical and finite element (FE) numerical methods, an energy-based wrinkling prediction model for thin-walled tube bending is developed. A segment shell model is proposed to consider the critical wrinkling region, which captures the deformation features of the tube bending process. The dissipation energy created by the reaction forces at the tube–dies interface for restraining the compressive instability is also included in the prediction model, which can be numerically calculated via FE simulation. The validation of the model is performed and its physical significance is evaluated from various aspects. Then the plastic wrinkling behaviors in thin-walled tube bending are addressed. From the energy viewpoint, the effect of the basic parameters including the geometrical and material parameters on the onset of wrinkling is identified. In particular, the influence of multi-tools constraints such as clearance and friction at various interfaces on the wrinkling instability is obtained. The study provides instructive understanding of the plastic wrinkling instability and the model may be suitable for the wrinkling prediction of a doubly-curved shell in the complex forming process with contact conditions.

Hot Tube-Forming

“…At room temperature, poor ductility and large flow stress occur for Al alloy tube, Mg alloy tube, and Ti alloy tube; also, the multiple defects may occur with the above geometrical dimensions due to pronounced unequal bending deformation at the extrados and intrados of bending tubes (83)(84)(85)(86). The bending formability should be improved when the forming temperature is elevated.…”

Dual Phase Steel Characterization for Tube Bending and Hydroforming Applications

“…The rotary draw mandrel bending process utilizes a specialized bender which incorporates a series of dies and a mandrel [53]. A schematic of this equipment can be seen in Figure 2.19.…”

FE modeling of a complete warm-bending process for optimal design of heating stages for the forming of large-diameter thin-walled Ti–6Al–4V tubes

“…Many scholars have studied the tube bending by combining the FE method with the experimental and analytical methods, especially applied to aluminum alloy tube and stainless steel tube [25][26][27][28][29]. Reliable FE models of cold tube bending were established so as to analyze stress and strain distribution, predict instability wrinkling behavior, solve springback problem, optimize process parameters and obtain qualified bent tube.…”