开孔Q460高强钢板在低周疲劳加载下的力学性能试验研究

为探讨单调拉伸及低周疲劳荷载下开孔Q460高强钢板的力学性能，对33个开孔材性试件进行试验测试，通过分析试件的应力-应变曲线、骨架曲线和耗能能力对比图，探讨了试件设计尺寸、开孔数量及加载模式等因素对开孔材性试件的强度、刚度、延性和耗能能力等力学性能的影响规律。在此基础上，使用ANSYS有限元分析软件建立了疲劳加载作用下开孔材性试件的精细有限元模型，并与材性试验结果进行了对比分析，验证了模型的正确性和可靠性。试验结果表明，开孔对Q460高强钢试件的力学性能有不利影响，导致应力集中加剧；在疲劳荷载作用下，增加试件轴向的开孔数量有利于提高试件的延性，但对钢材的耗能能力产生不利影响。开孔试件在低周反复荷载下易在开孔位置发生应力集中导致裂缝产生，且孔洞四周存在鼓曲现象，断后试件整体呈马鞍形。试件厚度对高强钢的破坏模式及力学性能影响显著，在低周疲劳荷载下，开孔试件的破坏形态与未开孔试件差别较大，且随厚度增加呈现两种不同的断口形态，随着试件设计厚度增加，断口截面与试件横截面呈约45°夹角和锯齿形交错相嵌两种断口类型；且随着钢材厚度的增加，试件的抗拉强度、延性和耗能能力均有所提高。加载模式对开孔Q460高强钢的抗拉强度影响较小，随着荷载循环圈数的增加，Q460高强钢的延性降低，耗能能力提高。

Experimental Study on Mechanical Properties of Q460 High-strength Steel Plate with Holes Under Low-cycle Fatigue Loadings

33 material specimens were tested to explore the mechanical properties of Q460 high-strength steel plate with holes under monotonic tension and low-cycle fatigue loadings. The stress-strain curve, skeleton curve and energy dissipation capacity comparison of the specimens were analyzed. The influence law of the design size of the specimen, the number of openings and the loading mode on the strength, stiffness, ductility and energy dissipation capacity of the specimens with holes were discussed. On this basis, a finite element model of specimen under fatigue loading was established by the ANSYS software to verify the correctness and reliability of the model. The test results show that round holes have an adverse effect on the mechanical properties of specimens. The holes lead to stress concentration of specimens. Under the fatigue loads, increasing the number of axial holes of the specimens is beneficial to improve the ductility of specimen, but has an adverse effect on the energy dissipation capacity of the steel. Under low-cycle repeated loadings, the specimens usually cracked and destroyed near holes, and the failure shapes are saddle-shaped. The thickness of the specimens has a significant impact on the failure mode and mechanical properties of the high-strength steel. Under the fatigue loads, the damage forms of the opening specimens and the non-open tester are different, and two different fracture forms are exhibited as thickness. With the increase of the design thickness of the specimen, the fracture section shows two forms. With the increase of the thickness of the steel, the mechanical properties of the specimens have improved significantly. As the number of load cycles increases, the ductility of Q460 high-strength steel decreases and the energy consumption capacity increases.