基于Bazier效应的薄壁管材连续矫直截面变形研究

Research of Section Deformation of Brazier Effect in Continuous Straightening a Thin-walled Tube

薄壁管材在连续矫直过程中会在大弯曲变形阶段发生截面扁化(即Bazier效应),最大扁化量作为重要工艺参数,用以控制截面变形程度防止管材屈曲失稳。而目前现场仍沿用经验图表结合人工经验和反复试矫对其进行估定,亟待建立针对性的最大扁化量数学模型以指导生产,为此在对薄壁管材弯曲扁化变形应变分析的基础上,基于薄壳弹塑性理论及其相关假设,确定管材单位长度的应变能,运用最小势能原理得到最大扁化量解析模型,该模型与管材轴线的弯曲半径、管材的材料参数和几何参数有关。在应用现场试验证明有限元动态仿真可行性的基础上,通过大量仿真试验证明数学模型的正确性,为继续深入研究矫直相关工艺参数的合理设置、完善薄壁管材矫直理论体系奠定基础。

It is well known that bending of the thin-walled tubes when continuous straightening induces ovalization to the tube cross-section（that is called the Brazier effect）, the maximal cross-sectional deformation as the main straightening technical parameter, is used to control the deformation degree under buckling limit, however, it is usually carried out based on the experiential data and chart by skilled labourers, whose art is based on long experience and experiments, the special theoretical model of the maximal cross-sectional deformation is immediately necessary. Therefore, the normal strain components are firstly obtained for the Brazier effect of the thin-walled tubes, and the strain energy of the thin-walled tube per unit length is got subsequently based on the elastic-plastic theory and relevant hypothesis of the thin-walled member, finally the mathematical model of maximal cross-sectional deformation in terms of curvature, material properties and geometric parameters of a tube, is presented by the principle of minimum potential energy. In order to certify whether it is correct, we have done some local experiments and also dynamic simulations by ANSYS/LS-DYNA, the results have shown that that the model is correct. This research can provide the basis for optimizing straightening technical parameters and completing the theory of thin-walled tube straightening.