中文摘要：

采用力学分析和数值模拟方法对圆角部位在内高压成形过程中的应力分布和变形机理进行分析,揭示出圆角和直边过渡区的减薄以及开裂的力学机理.提出内高压成形中圆角和直边的过渡区材料最易满足塑性屈服条件,并发生厚度方向的压缩应变,因此在过渡区易发生剧烈的减薄变形：并且当管材壁厚与圆角半径的比值大于0.5时,直边区和圆角区的屈服条件差别较大,引起变形不均匀性增大,更易导致过渡区的过度减薄和开裂.分析结果有助于指导内高压成形零件设计和工艺设计,改善矩形断面零件内高压成形件产品质量.

英文摘要：

The stress distribution and deformation pattern of the comer are analyzed by mechanical analysis and numerical simulation, and then the mechanism of thinning and cracking at the transition region is disclosed. It is presented that the material at the transition region is the easiest region to satisfy plastic yielding conditions and produce thickness compressive strain. Therefore severe thinning deformation is easy to occur at the transition region and when the ratio of wall thickness to comer radius is bigger than 0.5, the difference of yielding conditions between straight side and comer is more significant so that the deformation nonuniformity is increased, and is easier to induce the excessive thinning and cracking. The result is useful for lightweight part design and process design of tube hydroforming （internal high pressure forming） to improve product quality.