摘要
为研究韧性材料单轴拉伸试样的颈缩规律及颈部应力场的分布,对Q235钢、14CrNiMoV合金钢、LY12铝合金等三种典型的金属材料光滑试样和切口试样进行了单向拉伸试验,通过研究材料屈服过程的细观机理和颈缩部位最小截面上不同位置处孔洞大小和形状的变化规律,分析了颈部应力解Bridgman公式中主要试验和理论上的依据和假设,并给出了影响颈部应力场分布的主要因素。结果表明:Bridgman公式中等轴假设基本成立,屈服条件应用不合理,且颈缩部位的复杂应力场并非由颈缩部位最小截面的全面屈服和材料塑性流动导致,颈缩后构件几何形状的变化是引起应力场重新分布的主要因素。
The stress distribution of the necking part in the tensile specimen of ductile material is very important for understanding the essence of fracture,but there is still not a well-accepted theory that could interpret the reason for the occurrence of necking and the solution of stress field in the necking part currently,which brings the inconvenience to practical application.In this article,the uniaxial tension tests of three common metal materials including Q235 steel,14CrNiMoV alloy steel,and LY12 aluminium alloy are conducted using smooth and notched specimen,through studying the meso-scopic mechanisms of yielding process and change rules of the shape and size of voids in the minimum cross section of the necking part,the reasonableness of the primary hypothesis of Bridgman formula is evaluated,and the main factors affect stress distribution of the necking part are presented.Results obtained show that,the equiaxial assumption of Bridgman formula is true,but the application of yield condition to solve the stress field of the necking part is unreasonable.The complex stress redistribution in the necking part is not caused by the plastic flow and the general yielding in the minimum cross section of necking part,but due to the change of geometric shape of the necking part.
出处
《应用力学学报》
CAS
CSCD
北大核心
2013年第4期488-492,642,共5页
Chinese Journal of Applied Mechanics
基金
国家自然科学基金(10972180)
