Papers by Keyword: Fatigue Reliability

Abstract: In order to consider the fluctuating wind load induced fatigue problem of long span suspension bridge, fatigue reliability formula is modified by assuming the fatigue life is accord with the weibull distribution. Based on the accurate bridge buffeting analysis of time history, the stress time history of components of a suspension bridge in east sea China is simulated, and then the fatigue damages and reliabilities are calculated. The results indicate that the main cables and hangers have enough fatigue reliability under the fluctuating wind load, the fatigue failure will not occur; the stiffening girder has larger fatigue damage, under 40 / (m.s-1) mean wind speed action, the girder of mid-support section’s average fatigue life is only 3.103 years, so the girder’s damage under strong wind action should be taken seriously.

Abstract: The ANN-based optimization design for considering fatigue reliability requirements on structure was proposed in this paper. The ANN-based response surface method was used to analysis fatigue reliability of the structure. The fatigue reliability requirements were taken as constraints while the structural weight as the objective function, the ANN model was performed to simulate the relationship between the fatigue reliability and geometry dimension of the structure, the optimization result of the structure with a minimum weight was obtained, thus can make economic benefit meanwhile ensure the safety of the structure.

Abstract: To get a way of calculating the reliability of fatigue life of torsion spring, the paper discussed the optimal design of fatigue reliability for cylindrical helical torsional spring with Monte-Carlo method, and tried to build a new method to analyze the fatigue reliability of cylindrical helical torsional spring. The new method could test different values of parameters of a spring, and it could calculate the fatigue reliability of the spring in every parameter value with about 100 thousand test points with Monte-Carlo method, which can be set to get a better result, and it gave the comparison and selection to designers finally. The method was run with the software-MATLAB. The paper gave an example at last, and it compared the new methods results with ones of traditional design and discussed the differences.

Abstract: The elastic oil sump is commonly used as support parts in large-scale thrust bearing. It often operates under fluctuating load conditions during service. So, fatigue analysis of the material of the elastic oil sump is of great significance. In order to obtain the fatigue design data of the material of the elastic oil sump, the systematic tests on uniaxial tension-compression fatigue at room temperature are made. The fatigue limits and the fatigue life curves of the steel of the elastic oil sump are determined at different cyclic stress ratio. The P-S-N equations are calculated by the probabilistic methods. The test results provide a theoretical basis for the safety of life assessment of the elastic oil sump.

Abstract: The main objective of this paper is aim to take fatigue reliability updating evaluation of hydraulic steel gate based on the Bayes theorem. The fatigue cracks can be detected for existing structures, and fatigue reliability assessment can be updated by the nondestructive inspection. In this paper, based on the probabilistic characteristics for NDI techniques and the Bayes theorem, a fatigue reliability updating assessment model for existing steel gate components is proposed. The results showed that the fatigue reliability will increase with no cracks detected, decrease with unknown cracks detected, and change remarkably with cracks detected.

Abstract: This study developed a fatigue reliability method for evaluating and improving the key parts on railway vehicles, which was applied to real structures. The study involved a type of single-arm current collector, while its contact shoe often collapsed in operation and needs improvements. The dynamic stress data from the actual line was tested and converted to load spectra based on damage consistency rule, and then the fatigue life of the contact shoe structure was achieved. The calculation result comes to correspond to its operation life. Based on the method, an improving plan for the structure was developed under optimizing algorithms.

Abstract: The ANN-based optimization for considering fatigue reliability requirements in structural optimization was proposed. The ANN-based response surface method was employed for performing fatigue reliability analysis. The fatigue reliability requirements were considered as constraints while the weight as the objective function, the ANN model was adopted to establish the relationship between the fatigue reliability and geometry dimension of the structure, the optimal results of the structure with a minimum weight was reached.

Abstract: To obtain fatigue design data of the train wheel steel , the fatigue tests were carried out for the steel of K type and B type train wheel separately, which fatigue limit was measured using the fluctuation method, the fatigue life of two kinds of wheel steels were tested using the grouping method at the three stress levels, two different materials and different structures have an influence on the fatigue properties of the wheels using reliability principle. The fatigue life distribution of the B type is scattered relatively . S-N curve equation and P-S-N curve equation of the two kinds of steel were calculated . The theoretical basis were put up for developing design standards and safety evaluation of the both wheel.

Abstract: When drillstring rotates through the bending section of horizontal well, the fatigue damage of drillstring will be caused by alternating bending stress. Therefore, a thought to solve the fatigue reliability problem of drillstring in bending section of horizontal well is proposed. The variable amplitude alternating stress is transformed into equivalent fatigue stress, and the fatigue damage of drillstring is analyzed. Considering Palmgren-Miner rule and S-N curve, the fatigue life and reliability evaluation model of drillstring in bending section of horizontal well is established according to the fatigue reliability theory and probabilistic fracture mechanics. This model can calculate the fatigue damage, fatigue life and reliability of drillstring in the process of drilling and the maximum allowable dogleg angle where the drillstring is under compression and tension. And it has the important reference value for the fair use of drillstring and casing program design.

Abstract: To obtain fatigue design data of the CL50A steel for meeting best fatigue reliability , The fatigue tests were carried out for the CL50A steel, the fatigue life of the steel were tested using the grouping method at the three stress levels. Using probability method, S-N curve equation and P-S-N curve equation of the steel were calculated , the estimation equation of P-S-N curve with any reliability was worked out, the theoretical basis were put up for developing design standards and safety evaluation of the steel.