包辛格效应对板材拉弯回弹的影响

Influence of Bauschinger effect on springback in sheet metal stretch bending

为从理论上研究包辛格效应对板材拉弯回弹的影响,利用随动强化本构方程,采用数值方法,确定拉弯的应力分布,由此计算回弹,并与按等向强化本构方程计算的结果加以比较,根据应力分布的特点,分析包氏效应对拉弯回弹的作用.研究结果表明,对于先拉后弯,包氏效应有利于降低回弹,但由于预拉伸量较小,或反向加载区域较小,其影响不大;对于先弯后拉,包氏效应不利于减小回弹,但由于应变中性层曲率半径与内弯矩的变化相互制约,其影响也不大.

To theoretically investigate the influence of Bauschinger effect on springback in sheet metal stretch bending, the constitution relation of a kinematic hardening was used to determine the stress distributions of stretch bending by numerical calculation, so that the springback was calculated. They were compared with the results calculated according to the constitution relation of an isotropic hardening. The function of Bauschinger effect on springback during stretch bending was analyzed in accordance with the distinguishing feature of those distributions. The results of investigation show that in bending after stretch Bauschinger effect is beneficial to decreasing the springback and its influence is little, for small is either pre-stretching or the zone which loads in the opposite direction are acting on; and that in stretching after bend it is detrimental to reducing the springback, but its influence is not evident, for alteration to the inner bending moment and the curvature radius of strain neutral surface is restricted mutually.