不同控制方式对DP980钢双向拉伸性能的影响

Influence of different control methods on biaxial tensile properties of DP980 steel

以DP980钢为研究对象,利用双向拉伸试验机采用载荷控制、应变控制和位移控制的加载方式开展了拉伸比例为4∶1、4∶2、4∶3、4∶4、3∶4、2∶4和1∶4的双向拉伸试验。获得了3种控制方式7种拉伸比例下的双向拉伸应力-应变曲线,利用视频引伸计采集了粘贴在试样中心区域标记点的偏移量的变化过程,分析了材料在3种稳定控制方式下的加载历史及双向拉伸曲线。结果表明,3种控制方式下获得的双向拉伸曲线之间差异非常明显,即使材料在两个加载方向的拉伸比例相同,由于各向异性的影响,其应力和应变也并不相同,应变控制试验的标记中心点偏移量最小,位移控制试验过程中的载荷和应变的变化趋势较大。

Taking DP980 steel as the research object,the biaxial tensile test machine was used to carry out biaxial tensile tests with tensile ratios of 4∶1,4∶2,4∶3,4∶4,3∶4,2∶4 and 1∶4 using loading methods of load control,strain control and displacement control.The biaxial tensile stress-strain curves with seven tensile ratios and three control methods were obtained,the offsets change process of the marked point pasted at the center of the specimen was collected with a video extensometer,and the loading history and biaxial tensile curves of the materials under three stability control methods were analyzed.The results show that there are obvious differences between the biaxial tensile curves obtained under three control methods,even if the tensile ratios of the material in two loading directions are same,its stress and strain are not same due to anisotropy.The marked center point has the smallest offset in the strain-controlled test,the change of load and strain during the displacement-controlled test is large.