高强钢拼焊板V形模压弯曲回弹数值预测

Numerical Prediction on Spring-back of High Strength Steel Tailor Welded Blanks V-die Bending Process

基于ABAQUS有限元软件的UMAT和VUMAT接口,利用径向回退映射算法开发变模量的各向同性强化、线性随动强化和非线性随动强化的本构模型,耦合Aitken算法提高了非线性随动强化模型的收敛速度。利用耦合变模量的三种强化准则的模型,基于显式计算成形隐式计算回弹算法,在不同模压力和不同凸模圆角半径下对高强钢拼焊板V形模具弯曲的回弹进行预测,通过试验验证耦合应力相关变模量的非线性随动强化模型的回弹预测精度较高,最大预测误差为2.2%。应用此模型在不同凸模圆角半径和不同模压力下对高强钢拼焊板V形模具弯曲回弹后模量场和卸载后弯曲角进行预测与分析,拼焊板厚侧母板模量变化区较薄侧母板变化区域大,并在凸模圆角与直边过渡段上方出现反弯区。卸载后弯曲角随凸模圆角半径增大而增大,随着模压力的增大而减小。验证通过施加不同模压力可提高高强钢拼焊板V形模具弯曲工艺柔性的正确性,为进一步研究高强钢拼焊板V形模具弯曲自适应成形奠定基础。

Loop circuit incremental method is applied to error analysis of multi-loop parallel mechanism, and presents the loop circuit selection principle. Based on D-H parameter and characteristics of mechanism with actuation redundancy, the error model of spherical 2-DOF parallel manipulator with actuation redundancy is established by virtue of loop circuit incremental method which includes both position error and posture error. In the error model, mechanical structural parameter error is considered, at the same time, considering the deviation between axis of each revolute joint and center of sphere from the reason of processing and assembling etc. These make the error model more close to actual project. Based on the error model, the reason of jammed phenomenon which spherical mechanism appears is further analyzed, and the mechanical error is estimated. This lays a theoretical foundation for kinematics calibration research of the prototype.