中文摘要：

为解决传统技术无法制造大径厚比、小弯曲半径铝合金薄壁弯管的难题，提出采用双层管充液弯曲新方法。运用数值模拟研究厚度比和内压对低碳钢／铝合金双层管充液弯曲过程中起皱行为和壁厚分布的影响。结果表明，随着厚度比的增加，起皱的现象得到缓解直至消除，内层弯管外侧减薄率逐渐减小，壁厚分布更为均匀；随着内压的增加，起皱现象逐渐延缓，内层管壁厚最大减薄率增加，因此增加厚度比和内压均有助于提高双层管弯曲成形的稳定性。通过实验成功研制出径厚比为63的铝合金薄壁弯管件，外侧最大减薄率为24％。

英文摘要：

Hydroforming process of double-layered tube is proposed to solve the wrinkling encountered in manufacturing the ultra thin elbows with traditional bending processes. The numerical simulation of hydroforming of carbon steel/aluminium alloy double layered tubes were conducted to investigate the influences of internal pressure and thickness ratio on wrinkling and wall thickness distribution of the double-layered tube. It is shown that the maximum wall thinning of the outer elbow decreases and the wrinkling eliminates as the thickness ratio increases, which implies a uniform wall thickness distribution. With inner pressure increases, the inner thinning rate decrease gradually, and the wrinkling was delayed. So increase thickness ratio and pressure are helpful to improve the stability of double-layered tube. The hydro-bending experiments are carried out to obtain successfully the thinwalled elbow tubes with bending angle is 70°. The outer maximum thinning rate was 24%. Results proved that double-layered tubes hydroforming is suitable for manufacturing large diameter-thick ratio of ultra thin-walled tube.