基于三维DIC方法的高强钢拉伸力学性能测定

高强度钢在建筑等工程领域发挥着极为重要的作用，因此准确测定其力学性能具有至关重要的意义．鉴于传统机械引伸计在小尺寸试样变形测试中的不便性，利用三维数字图像相关(3D-DIC)方法，对8.8级螺栓和Q690钢这两类试样在单轴拉伸试验全过程中的变形进行了测试，分别得到了应力-应变曲线、弹性模量、屈服强度、强度极限、断后延伸率和断面收缩率，由于试样在屈服阶段应变增加而应力基本不变，因此同时研究了该阶段中试样从弹性变形演化到塑性变形的发展规律．实验结果表明三维DIC在小尺寸试样力学性能测试方面具有很强的优越性，可用来灵活地测量变形并研究变形的演化规律．

The Measurement of Tensile Mechanical Properties of High-Strength Steel Using Three-Dimensional Digital Image Correlation

High-strength steel plays a very important role in engineering fields such as construction, therefore accurate determination of its mechanical properties is of great importance. Considering the inconvenience of conventional mechanical extensometer applied to deformation measurement of small-scale specimens, we used three-dimensional digital image correlation (3D-DIC) to measure the deformation of grade 8.8 bolts and Q690 high-strength steel specimens under the uniaxial tensile test and obtained the stress-strain curves, elastic modulus, yield limit, ultimate strength, percentage of elongation after fracture and percentage of area reduction after fracture. Moreover, owing to the phenomenon of stress remaining constant with the strain increasing in yielding stage, the evolution process from elastic deformation to plastic deformation of the specimens was studied as well. Experimental results show that 3D-DIC has strong advantages on the determination of mechanical properties of small-scale specimens and could be used to measure the deformation flexibly and study the deformation evolution process of such specimens.