Problem of the Uniform and Variable Speed of Loading About Metal Subjected to Asymmetrical Cycling Loads
XIAO Min1, LUO Yingshe1, 3, SI Jiayong2, LIU Xiubo1, 3
1 Institute of Rheological Mechanics and Materials Engineering, Central South University of Forestry and Technology,Changsha 410004; 2 School of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha 410004; 3 Hunan Province Key Laboratory of Engineering Rheology, Central South University of Forestry and Technology, Changsha 410004
Abstract: According to damage mechanics, fatigue is caused by the evolution of the damage inside the material, but the mec-hanism is not clear. Therefore, the molecular theory of fracture in polymer physics is extended to be applied to metal fatigue damage. It is found that fracture of metal is a relaxation process, and macro fracture is ascribed to a thermal activation of the microscopic atomic bond breaking. Taking Q235 steel as an example,the testing of the tension and compression of asymmetrical cycle is carried on the CMT5105 universal electronic testing machine. From the view of atomic bond dissociation and combined with the experimental data, the concrete form of asymmetrical cycle fatigue damage evolution under the constant and variable loading rates in multiple factors is discussed and deduced. Then a new fatigue damage evolution is proposed by taking the rate as the main consideration, the basic forms of damage evolution under the conditions of constant and variable rates are discussed respectively, and rate dependent parameter factors are modified. The results show that the new fatigue damage evolution is simple in form, few in parameters, wild in application, and is better fitted with the experimental results.
肖敏, 罗迎社, 司家勇, 刘秀波. 金属非对称循环下的匀变速加载问题[J]. 《材料导报》期刊社, 2018, 32(4): 676-680.
XIAO Min, LUO Yingshe, SI Jiayong, LIU Xiubo. Problem of the Uniform and Variable Speed of Loading About Metal Subjected to Asymmetrical Cycling Loads. Materials Reports, 2018, 32(4): 676-680.
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2018, Vol. 32 
