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为了研究板料弯曲成形时圆角的应力和应变变化规律,首先对U型钢弯曲时圆角部位的应力分布进行了理论分析,分析可知:板料弯曲段圆角处的外层切向应力向中性层逐渐减小,在外表面处达到最大值为1.156σs0;内层的切向应力在内表面最小其绝对值为1.156σs0。采用有限元软件ANSYS/LS-DYNA建立了模型模拟分析了厚度分别为4和6 mm的板料成形过程,模拟可知:圆角处的应力大小与板料的相对弯曲半径有关;圆角部位的应力值大于屈服强度且小于抗拉强度,说明圆角部位发生弹塑性变形。通过建立板料冷弯成形测试装置对板料圆角部位的应变进行了分析,分析可知:板料成形时圆角处的应变大小与板料的相对弯曲半径有关,应变值随弯曲角度的增大不断增加,离圆角部位的距离的越远,变形减少的越快。
In order to study the regularity of the stress and strain of the fillet in the bending process of sheet metal, the stress distribution of the fillet part in the bending of the U-shaped steel is analyzed theoretically. The analysis shows that the outer tangential stress The neutral layer decreases gradually, reaching a maximum value of 1.156σs0 at the outer surface. The inner layer has a minimum tangential stress of 1.156σs0 at the inner surface. The finite element software ANSYS / LS-DYNA was used to establish a model to simulate the sheet metal forming process with the thickness of 4 and 6 mm. The simulation shows that the stress at the fillet is related to the relative bending radius of the sheet; The stress value is greater than the yield strength and less than the tensile strength, indicating elastic deformation occurs at the fillet. Through the establishment of sheet cold forming test device on the sheet fillet part of the strain analysis shows that: the sheet metal forming the fillet at the size of the strain and the relative bending radius of the sheet, the strain value increases with the bending angle Large increases, the distance from the fillet the farther away, the faster the deformation reduction.