Fatigue
Mazuri Erasto Lutema; Awel Mohammedseid Momhur
Abstract
The most crucial parts that literally sustain the safety of railroad rolling stock from the subfloor are the wheels. However, during operation, several random parameters can impair their performance, resulting in the train's unsafety. These unpredictable characteristics can lead to fatigue failure, especially ...
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The most crucial parts that literally sustain the safety of railroad rolling stock from the subfloor are the wheels. However, during operation, several random parameters can impair their performance, resulting in the train's unsafety. These unpredictable characteristics can lead to fatigue failure, especially in a CHR2 high-speed train. This study aims to analyse the fatigue life of railway wheels for the CHR2 high-speed train due to different random parameters. Three scenarios with random parameters were considered: suspension system, passenger weight, and train speed. A 3D wheel model created by CAD and analyzed with finite element software ANSYS and nCode to validate the model by applying static force. A railway vehicle-track dynamics model with a 30t axle load using the vehicle-track dynamics theory. Then Monte Carlo simulations performed to produce random samples of sensitive parameters and analyze their effect distributions on wheel–rail contact under random wheel parameters. The findings demonstrate that the random parameters of the suspension system have more negative effects on fatigue life compared to random passengers’ weight and train speed, however, random passengers’ weight has a less negative impact compared to random suspension and passenger weight. But also, the dynamic results stress analysis showed that the random suspension system parameters have a high maximum stress compared to the stress obtained from random passengers’ weight and train speed. Moreover, the random suspension system parameters have high maximum stress compared to stress obtained from random passengers’ weight and train speed.
Fatigue
Liela Abbasiniyan; Seyed hamed Hoseini; Shirko faroughi
Abstract
In this paper, the crack propagation and branching in the pre-cracked and notched samples have been modeled using nonlocal peridynamic theory. The bond-based peridynamic model has been numerically implemented which make it possible to simulate various features of dynamic brittle fracture such as crack ...
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In this paper, the crack propagation and branching in the pre-cracked and notched samples have been modeled using nonlocal peridynamic theory. The bond-based peridynamic model has been numerically implemented which make it possible to simulate various features of dynamic brittle fracture such as crack propagation, asymmetries of crack paths and successive branching. The fracture simulation of thin plates made of a brittle material with different crack and notch patterns has been considered. The molecular dynamics open-source free LAMMPS code has been updated to implement the peridynamic theory based modeling tool for two-dimensional numerical analysis. The simulations show that, the simulation time significantly decreases which is the core and distracting deficiency of the peridynamic method. Moreover, the simulated results demonstrate the capability of peridynamic theory to precisely predict the crack propagation paths as well as crack branching during dynamic fracture process. The good agreement between simulation and experiments is achieved.
Fatigue
J. Amirian; H. Safari; M. Shirani; M. Moradi; S. Shabani
Abstract
Generally, fatigue failure in an element happens at the notch on a surface where the stress level rises because of the stress concentration effect. The present paper investigates the effect of a notch on the fatigue life of the HSLA100 (high strength low alloy) steel which is widely applicable in ...
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Generally, fatigue failure in an element happens at the notch on a surface where the stress level rises because of the stress concentration effect. The present paper investigates the effect of a notch on the fatigue life of the HSLA100 (high strength low alloy) steel which is widely applicable in the marine industry. Tensile test was conducted on specimens and mechanical properties were obtained. Rotating bending and axial fatigue tests were performed at room temperature on smooth and notched specimens and S-N curves were obtained. Using the obtained S-N curve for smooth specimens, the fatigue strength factor for the notched specimens were predicted by Weibull's weakest-link, Peterson, Neuber, stress gradient and critical distance methods and compared with experimental results. It was found that the critical distance and also Weibull’s weakest-link methods have the best agreement with experimental results.
Fatigue
M. Jooybari; J. Shahbazi Karami; M. Sheikhi
Abstract
In the present study, mechanical properties and low cycle fatigue behavior of a solid-solutionized AA6061 aluminum alloy produced by equal channel angular pressing (ECAP) process were investigated. The grain refinement after two passes of ECAP significantly increased the yield stress and ultimate tensile ...
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In the present study, mechanical properties and low cycle fatigue behavior of a solid-solutionized AA6061 aluminum alloy produced by equal channel angular pressing (ECAP) process were investigated. The grain refinement after two passes of ECAP significantly increased the yield stress and ultimate tensile stress and decreased the ductility of the alloy. However, the improvement of low cycle fatigue strength was not as remarkable as expected. Post-ECAP aging heat treatment to the peak-aging condition imposed a notable change in the strength and ductility of the alloy so that its fatigue strength partly enhanced. An optimized combination of grain refinement and distributed fine precipitates in the matrix of the alloy was achieved by conducting aging heat treatment between passes of ECAP. The proposed procedure was proved to yield the best combination of strength and ductility, better distribution and size of precipitates, and thus a remarkable improvement in the low cycle fatigue response of the investigated material.
