【摘要】 双脊矩形管在其绕弯成形过程中极易出现截面变形等缺陷,严重制约了其成形质量及成形极限的提高。管材的截面变形主要由各阶段的应力状态决定,研究管材应力变化规律有助于提高对绕弯变形机理的认识,进而为减少截面变形策略的制定提供指导。运用ABAQUS/Explicit软件,建立了双脊矩形管绕弯成形三维有限元模型,并通过实验验证了该模型的可靠性。基于该模型,将双脊矩形管弯曲部分分为芯模支撑区和无芯模支撑区2个区域,分别研究了双脊矩形管绕弯成形过程中内外腹板及内外脊槽对称线上的特征点B1、B2、B3、B4的等效应力、切向应力和周向应力在2个区域的变化规律。研究结果表明:当截面位于芯模支撑区时,该截面内外腹板对称线上的点B1、B2上的等效应力、切向应力及周向应力均出现不同程度的波动,内外脊槽对称线上的点B3、B4上的应力值没有出现明显的波动现象,但B3上的切向应力、周向应力出现反向加载现象;当截面位于无芯模支撑区时,应力变化比较平缓。更多还原

【Abstract】 The cross sectional deformation of DRRTs occurs easily in rotary draw bending,which largely restricts the improvement of bending quality and forming limit.The cross sectional deformation of a tube enormously depends on its stress state,so it is benefit to enhance the knowledge of deformation mechanism by studying the stress variation and then it is helpfnl to develop method for decreasing cross sectional deformation.Based on the platform of ABAQUS/Explicit,a three-dimensional finite element model of DRRT in rotary draw bending was established and its reliability was validated by experiment.Dividing the bended portion of DRRT into two zones,MSZ(mandrel support zone)and NMSZ(no mandrel support zone),variation laws of equivalent stress,tangent stress and circumferential stress at the feature points B1-B4 on the symmetric lines of flanges and ridge grooves of DRRT were studied with the aid of this model.The results show that when the section is located in the MSZ,the equivalent stress,tangent stress and circumferential stress of B1 and B2fluctuate on different levels.The similar phenomenon does not occur for the stresses of B3 and B4,but the tangent stress and circumferential stress of B3 generate reverse loading phenomenon.When the section lies in the NMSZ,the stresses change gently.更多还原