scholarly journals The Effect of Material Static Mechanical Properties on the Fatigue Crack Initiation Life of Rail Fastening Clips

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Y. Liu ◽  
Qiutong Li ◽  
Xiujie Jiang ◽  
Huan Liu ◽  
Xianpu Yuan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fatigue Crack ◽  
Elastic Modulus ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Uniaxial Tensile ◽  
Static Mechanical ◽  
Crack Initiation Life ◽  
Static Mechanical Properties

This paper aimed to study the effect of material static mechanical properties on the fatigue crack initiation life of ω-shaped rail fastening clips, in which the Vossloh 300-1 fastener system was taken as an example. The static mechanical properties of 38Si7 steel (the material of the clip) were first investigated through a series of uniaxial tensile tests. According to the experimental outcomes, a classic assembly system was simulated afterwards using the finite element analysis (FEA) method. On the basis of the Brown–Miller criterion, an in-depth numerical study regarding the critical plane was realized, which allowed fatigue crack initiation to be successfully reproduced by FEA. Finally, a detailed parametric study was performed with the relevant sensitivity analysis. The results showed that the initiation and progression of fatigue cracks in the fastening clip occur in the plane of the maximum shear strain. The fatigue crack initiation life of the fastening clip was extremely sensitive to the elastic modulus, especially more sensitive to the tensile strength. From an engineering viewpoint, the fatigue resistance of the fastening clip could be boosted by (i) increasing the tensile strength of the material to at least 1450 MPa and (ii) rendering the elastic modulus smaller than 160 GPa.

Assessment Technology of Fatigue Crack Initiation Life of Weld Structures

2017 ◽  
Vol 86 (1) ◽  
pp. 56-58
Author(s):  
Seiichiro TSUTSUMI ◽  
Fincato RICCARDO ◽  
Mitsuru OHATA ◽  
Tomokazu SANO
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Assessment Technology ◽  
Crack Initiation Life

Experimental Investigation into the Influences of Weathering on the Mechanical Properties of Sedimentary Rocks

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xiaoshuang Li ◽  
Yingchun Li ◽  
Saisai Wu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Friction Coefficient ◽  
Uniaxial Compression ◽  
Sedimentary Rocks ◽  
Uniaxial Tensile ◽  
Mechanical Parameters ◽  
Uniaxial Tensile Strength ◽  
Weathering Grades

The time-dependent behaviors of the sedimentary rocks which refer to the altering of the mechanical and deformable properties of rock elements in the long-term period are of increasing importance in the investigation of the failure mechanism of the rock strata in underground coal mines. In order to obtain the accurate and reliable mechanical parameters of the sedimentary rocks at different weathering grades, the extensive experimental programs including the Brazilian splitting test, uniaxial compression tests, and direct shear tests have been carried out on the specimens that exposed to the nature environments at different durations. The correlation between the weathering grades and mechanical parameters including uniaxial tensile strength, uniaxial compression strength, elastic modulus, Poisson’s ratio, cohesion, and friction coefficient was proposed. The obtained results suggested that uniaxial tensile strength, uniaxial compressive strength, elastic modulus, and cohesion dramatically decreased with increasing weathering time, characterized as the negative exponential relationship in general. The influences of various weathering grades on fracture behavior of the rock specimens were discussed. The cumulative damage of the rock by the weathering time decreased the friction coefficient of the specimens which led to the initiation and propagation of microcrack within the rock at lower stress conditions. The obtained results improved the understanding of the roles of weathering on the mechanical properties of sedimentary rocks, which is helpful in the design of the underground geotechnical structures.

The Variational Principles of Coupled Systems in Fatigue Problem Undergoing Large Range Damage

2016 ◽  
Vol 835 ◽  
pp. 514-520
Author(s):  
Wen Feng Tan
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Potential Energy ◽  
Large Range ◽  
Fatigue Crack Initiation ◽  
Form Solution ◽  
Coupled Systems ◽  
Energy Principle ◽  
Potential Energy Principle ◽  
Crack Initiation Life

The coupled systems of fatigue crack initiation problem undergoing large range damage is defined. The zero different work principle, coupled potential energy principle, coupled complementary energy principle in the coupled system is established. By using of coupled potential energy principle, Closed form solution about predicting fatigue crack initiation life of three-dimensional component which leads to large range damage is derived. Compared with reference [1], the close form solution derived from this some. It is proved that the method is correct. The method adopted in this paper is definite in mechanical concept,it can be widely used in analysis of predicting fatigue crack initiation life of various component which leads to large range damage.

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