45号钢承载能力的原位三点弯曲试验研究
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摘要
利用自行研制的原位三点弯曲测试装置,研究了45号钢V型缺口试件在不同支撑跨距下和弯曲压头与试件中心线偏移量下的承载能力.首先,从理论上分析了三点弯曲的载荷-挠度曲线与偏移量、跨距的关系.然后,通过仿真模拟的von Mises应力最小塑性区半径估算了裂纹的萌生方向.最后,通过12组V型缺口试件的原位三点弯曲试验,获得并分析了不同跨距和偏移量下的三点弯曲载荷-挠度曲线,以及实时采集了弯曲载荷作用下裂纹的扩展情况.通过原位观测的方式建立了宏观力学性能与微观力学性能的联系.从材料损伤机理的角度分析了材料在不同的三点弯曲试验参数下承载能力的差异.
The load capabilities of 45~# steel V-notched specimens under the spans of the supporters and the offsets between the punch and the mid-span of the specimens are studied by the self-made in-situ three-point bending device. Firstly,the relationship of load-delection curves and offsets and spans are analyzed theoretically. Secondly,the simulated minimum plastic zone radius of von Mises stress is applied to estimate the initiation direction of the crack. Then the experimental threepoint bending loading-deflection curves under various offsets and spans are achieved and analyzed by in-situ TPB tests with 12 groups of V-notched specimens. Finally,according to the differences among the load-deflection curves,combining the in-situ images of specimen micro-structures,the initiation and propagation of the cracks due to bending loads are analyzed in real time. The relationship between macro-mechanical properties and micro-mechanical properties are established by in-situ observation. The difference of the load capabilities of materials under different three-point bending test parameters is analyzed from the perspective of damage mechanism.
The load capabilities of 45~# steel V-notched specimens under the spans of the supporters and the offsets between the punch and the mid-span of the specimens are studied by the self-made in-situ three-point bending device. Firstly,the relationship of load-delection curves and offsets and spans are analyzed theoretically. Secondly,the simulated minimum plastic zone radius of von Mises stress is applied to estimate the initiation direction of the crack. Then the experimental threepoint bending loading-deflection curves under various offsets and spans are achieved and analyzed by in-situ TPB tests with 12 groups of V-notched specimens. Finally,according to the differences among the load-deflection curves,combining the in-situ images of specimen micro-structures,the initiation and propagation of the cracks due to bending loads are analyzed in real time. The relationship between macro-mechanical properties and micro-mechanical properties are established by in-situ observation. The difference of the load capabilities of materials under different three-point bending test parameters is analyzed from the perspective of damage mechanism.
引文
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[12]朱万成,唐春安,杨天鸿.偏三点弯曲岩石试件中裂纹扩展过程的数值模拟[J].东北大学学报(自然科学版),2002,23(6):592-595.(Zhu Wan-cheng,Tang Chun-an,Yang Tian-hong. Numerical simulation of crack growth process in rock speciments with partial three-point bending[J]. Journal of Northeastern University(Natural Science),2002,23(6):592-595.)
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[14] Hou P L,Fan Z Q,Zhang L,et al. An in situ three-point bending study on pre-notch 7075 aluminium alloy with acoustic emission[J]. Materials Transactions,2015,56(12):1977-1983.
[15]盖尔J M,古德诺B J.材料力学[M].北京:机械工业出版社,2011.(Gere J M,Goodno B J. Strength of materials[M]. Beijing:China Machine Press,2011.)
[16] Meyers M A,Chawla K K. Mechanical behavior of materials[M]. Cambridge:Cambridge University Press,2009.
[17]樊兆馥.机械设备安装工程手册[M].北京:冶金工业出版社,2004.(Fan Zhao-fu. Mechanical equipment installation engineering handbook[M]. Beijing:Metallurgical Industry Press,2004.)
[2] Wang N Z,Chen X,Li A. Three-point bending performance of a new aluminum foam composite structure[J].Transactions of Nonferrous Metals Society of China, 2016, 26(2):359-368.
[3] Xu S L,Reinhardt H W. Determination of double-K criterion for crack propagation in quasi-brittle fracture. Part Ⅱ:Analytical evaluating and practical measuring methods for three-point bending notched beams[J]. International Journal of Fracture,1999,98(2):151-177.
[4] Caminero M A,Rodriguez G P,Munoz V. Effect of stacking sequence on Charpy impact and flexural damage behavior of composite laminates[J]. Composite Structures,2016,136(1):345-357.
[5] Swetha C,Sato N,Folke T. Fracture toughness and failure mechanism of graphene based epoxy composites[J].Composites Science and Technology,2014,97(16):90-99.
[6] Hou P L,Zhao H W,Ma Z C. Influence of punch radius on elastic modulus of three-point bending tests[J]. Advances in Mechanical Engineering,2016,8(5):1-8.
[7] Liu C,Du D D,Li H G. Interlaminar failure behavior of GLARE laminates under short-beam three point bending load[J]. Composites Part B:Engineering, 2016,97(15):361-367.
[8] Zuo J P,Wang X S,Mao D Q. SEM in-situ study on the effect of offset-notch on basalt cracking behavior under threepoint bending load[J]. Engineering Fracture Mechanics,2014, 131(1):504-513.
[9] Xeidakis G S,Samaras I S,Zacharopoulos D A. Trajectories of unstably growing cracks in mixed mode Ⅰ-Ⅱ loading of marble beams[J]. Rock Mechanics and Rock Engineering,1997, 30(1):19-33.
[10]李一凡,董世明,黎坤运.三点弯曲型试件Ⅰ/Ⅱ复合型断裂的数值与实验研究[J].实验力学,2018,33(4):557-566.(Li Yi-fan,Dong Shi-ming,Li Kun-yun. Numerical simulation and experimental study of three-point bending specimen’sⅠ/Ⅱmixed mode fracture[J]. Experimental Mechanics, 2018,33(4):557-566.)
[11]夏雨,黄山,聂宏涛.基于塑性损伤模型的三点弯曲梁裂缝扩展规律研究[J].广西大学学报(自然科学版),2017,42(3):1170-1178.(Xia Yu,Huang Shan,Nie Hong-tao. Research of dynamic crack propagation of three-point bending beam based on damage model[J]. Journal of Guangxi University(Natural Science Edition),2017,42(3):1170-1178.)
[12]朱万成,唐春安,杨天鸿.偏三点弯曲岩石试件中裂纹扩展过程的数值模拟[J].东北大学学报(自然科学版),2002,23(6):592-595.(Zhu Wan-cheng,Tang Chun-an,Yang Tian-hong. Numerical simulation of crack growth process in rock speciments with partial three-point bending[J]. Journal of Northeastern University(Natural Science),2002,23(6):592-595.)
[13] Khan S,Khraisheh M K. A new criterion for mixed mode fracture initiation based on the crack tip plastic core region[J]. International Journal of Plasticity,2004,20(1):55-84.
[14] Hou P L,Fan Z Q,Zhang L,et al. An in situ three-point bending study on pre-notch 7075 aluminium alloy with acoustic emission[J]. Materials Transactions,2015,56(12):1977-1983.
[15]盖尔J M,古德诺B J.材料力学[M].北京:机械工业出版社,2011.(Gere J M,Goodno B J. Strength of materials[M]. Beijing:China Machine Press,2011.)
[16] Meyers M A,Chawla K K. Mechanical behavior of materials[M]. Cambridge:Cambridge University Press,2009.
[17]樊兆馥.机械设备安装工程手册[M].北京:冶金工业出版社,2004.(Fan Zhao-fu. Mechanical equipment installation engineering handbook[M]. Beijing:Metallurgical Industry Press,2004.)
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