焊缝管液压胀形模拟建模及变形规律的研究

基于周向显微硬度的分布及经验公式法,确立了STKM11A焊缝管热影响区的流动应力;通过对热影响区进行分片的方式,建立了包含焊缝和热影响区的焊缝管液压胀形的有限元模拟模型。基于该模型,模拟分析了STKM11A焊缝管液压胀形时的变形规律,如截面轮廓形状、周向壁厚分布和成形极限等,并与胀形实验结果进行对比。结果表明,液压胀形后焊缝管的截面轮廓形状不对称、壁厚分布不均匀,最小壁厚位于热影响区;包含焊缝及热影响区的有限元模型在预测焊缝管液压胀形的变形规律、极限载荷和潜在胀裂位置等方面,较其他常规模型更加精确。

Modeling approach and deformation behavior of a tailor-welded tube in hyfroforming

The flow stresses of the heat affected zone(HAZ) of the STKM11A welded tube are determined by an empirical law based on the Vikers Hardness(HV) distribution in circumferential direction of the tube.Finite element model including the weld and the HAZs of the welded tube in hydroforming is made by slicing the HAZ into strips with various flow stresses.The deformation behavior including the bulged profile in cross-section,wall thickness distribution in circumferential direction forming limit and so on is investigated by using the new model and compared with experimental results.The results show that the cross-section of the welded tube can not maintain a circular profile during the hydroforming,and a non-uniform thickness distribution in circumferential direction is observed with the minimum thickness locating within the HAZ.The results also imply that the new model can predict the deformation behavior,maximum pressure,and the potential burst location of the welded tube in hydroforming more accurately than other common models.