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金属板材的成形极限是板材成形领域中的重要性能指标和工艺参数。目前,国内外均已开展以厚度减薄率作为成形极限判据的成形极限试验模拟研究,其厚度减薄率的测试过程较为复杂,不适合实验室大批量检验工作。提出了2种金属板材拉伸厚度减薄率的测试方法,一种为人工测试断后试样断口附近厚度分布,得到厚度减薄率变化曲线;另一种方法是通过公式推导,将厚度减薄率与试样纵向应变联系起来,通过测试纵向应变,得到集中性失稳前的厚度减薄率变化规律。
The forming limit of sheet metal is an important performance indicator and process parameter in the field of sheet metal forming. At present, the forming limit test simulation with the thickness reduction rate as the forming limit criterion has been carried out at home and abroad. The testing process of the thickness reduction rate is complicated and it is not suitable for large-scale laboratory testing. Two kinds of testing methods for drawing thickness and thinning rate of metal sheet are proposed. One is to measure the thickness distribution near the fracture surface of specimen after manual testing, and the curve of thickness and thickness reducing rate is obtained. The other method is to deduce the thickness through the formula The rate is related to the longitudinal strain of the specimen. By testing the longitudinal strain, the change rule of the thickness reducing rate before the concentrated instability is obtained.