基于灰色系统理论的汽车横梁充液成形用坯料优化

Optimization for hydroforming blanks of a car beam based on the Grey system theory

类似汽车横梁这些复杂管类结构件的充液成形,是一个不均匀的变形过程,坯料的相对形状及尺寸,是影响金属流动的关键因素,从而对充液成形零件的最小壁厚、最大壁厚等评价对象有重要影响。以坯料的弯曲角度、弯曲半径、轴线高度差为因子,建立正交试验设计方案,进行有限元模拟,获得不同坯料尺寸下的最小壁厚、最大壁厚参考序列。利用灰色系统理论,计算各个参考序列与比较序列之间的关联系数,将多目标转化为以关联度为目标的单目标。进一步计算各坯料结构尺寸的平均关联度,获得优化的坯料尺寸组合参数,以此进行有限元模拟和生产实验。验证结果表明,该优化方法能够获得满足质量要求的充液成形的汽车横梁。

Metal flow is a inhomogeneous process during hydroforming of complex tubal parts such as the car beams, relative shape and sizes of the blank is the key factors which affect metal flow, and then have a significant effect on the quality of the car beams made by hydroforming, for example, can affect the maximum and minimum wall thicknesses of the parts. The bending angle, the bending radius and the axis drop of the blank axis were set as variances, orthogonal experiment was carried out by FEM, and then two reference sequences of the maximum and minimum wall thicknesses were obtained. Based on the Grey system theory, the relational coefficients between the comparison and the reference sequences were calculated and each multi-objective design can be transformed into a single objective design by the degree of grey relationship. The average degree of each level was calculated, and then, the optimum combination of structural size of the blank for hydroforming was obtained and was validate by FEM and hydroforming experiments. It is showed that the method of optimization design can meet the need of hydroforming a car beam with high forming quality.