Fatigue Life and Reliability Analysis of a Parallel Hip Joint Simulator

Robotica ◽  
2021 ◽  
pp. 1-15
Author(s):  
Feng Guo ◽  
Gang Cheng ◽  
Xin Yuan

SUMMARY Aiming at 3SPS+1PS parallel hip joint simulator, the maximum stress of branched chains under the suggested trajectory is obtained by elastodynamic analysis. Based on Corten-Dolan fatigue damage theory and Rain-flow counting method, the dynamic stress of each branched chain is statistically analyzed. The fatigue life prediction shows that branched-chain A2P2C2 is the weakest component for the simulator. Finally, the fatigue reliability is analyzed and the fatigue life and reliability under different structural parameters are discussed. The study shows that the fatigue life of each branched chain can be increased or balanced by increasing structural parameters or exchanging initial motion parameters.

2014 ◽  
Vol 1055 ◽  
pp. 161-164
Author(s):  
Tao Wang ◽  
Wei Zhong Zhang ◽  
Chen Xie ◽  
Deng Xia Zhang ◽  
Yan Ru

With the study subject of the gear transmission in an unmanned system, several common methods of fatigue life prediction are analyzed. According to the actual running state, S-N nominal stress method is used to predict the fatigue life of the gears. Based on the S-N data of the gear material and the linear cumulative damage theory, ANSYS is used to estimate the bending fatigue life of the gears, so as to obtain the fatigue life loss coefficient of the gears. It provides a reliable data reference of the design, use and maintenance of the gear transmission in unmanned system.


2010 ◽  
Vol 118-120 ◽  
pp. 17-26 ◽  
Author(s):  
Yong Xiang Zhao

For an engineering structure with an actual fatigue life over that corresponding to a so-called fatigue limit, appropriate reliability assessment and fatigue life prediction are essential for developing the structure and sustaining its high quality in service. Basic clues are explored. A competition fatigue initial mechanism is shown to provide a requirement of material primary quality management. Affordable deduced material and structural probabilistic S-N curves are presented by fitting into material mid-and-long life S-N data and fatigue limits and, then, comparing to structural fatigue limits. Random cyclic stress-strain relations are depicted for constructing random stressing history of structures. Reliability assessment and fatigue life prediction are established to synthetically consider the interference of applied stresses deduced from the random cyclic stress-strain relations and capacity strengths derived from the structural S-N relations with an expected life. Affordable and appropriate method has been then developed to realize the reliability assessment and fatigue life prediction including the super long life regime. Availability of the present method has been indicated through a reliability analysis to the velocity related reliabilities and fatigue lives of a railway axle.


2021 ◽  
Vol 13 (10) ◽  
pp. 168781402110524
Author(s):  
Hongxun Fu ◽  
Xiaoxia Chen ◽  
Qiang Zhao ◽  
Zhen Xiao ◽  
Xuemeng Liang

A mesh flexible spoke non-pneumatic tire is designed to avoid tire burst and other hidden dangers in the traditional pneumatic tires, and improve driving safety. The purpose of this study is to explore the fatigue performance and fatigue life prediction method of the non-pneumatic tire and analyze the influence of structural parameters on the fatigue life of non-pneumatic tire. Based on the crack propagation method of energy release rate by J-integral, the fatigue life of the meshed flexible spoke non-pneumatic tire is predicted. Using numerical simulation method, the influence of key structural parameters, such as the curvature, unit angle and thickness of the lateral spoke and the tread thickness, on tire fatigue life is studied. The results show that the fatigue life prediction method proposed can be used to predict the fatigue life of flexible spoke non-pneumatic tire, and the fatigue life of non-pneumatic tire with flexible spoke can be improved by selecting appropriate structural parameters, which could provide some reference for the structural optimization design of the fatigue performance of the non-pneumatic tire.


2012 ◽  
Vol 482-484 ◽  
pp. 736-740
Author(s):  
Xiao Mei ◽  
Da Shan Dong ◽  
Yuan Yuan Teng

Fatigue crack is very dangerous for safely operating of steel structures. To estimate precisely fatigue life of bridge cranes, the randomness of lifted load and trolley’s position should be considered. Therefore, bi-probability fatigue life prediction method, namely load and position probability, is put forward based on the miner linear cumulative damage theory. Stress cycle spectrum is constructed based on real-time monitoring data by rainflow counting method. This method can successfully explain the existence of girder cracks in a typical bridge crane RMG, so it would provide valuable reference for maintenance decision of in-service cranes.


Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 801
Author(s):  
Bo Sun ◽  
Junlin Pan ◽  
Zili Wang ◽  
Yi Ren ◽  
Dariusz Mazurkiewicz ◽  
...  

The influence of irradiation should be considered in fatigue reliability analyses of reactor structures under irradiation conditions. In this study, the effects of irradiation hardening and irradiation embrittlement on fatigue performance parameters were quantified and a fatigue life prediction model was developed. Based on this model, which takes into account the cumulative effect of a neutron dose, the total fatigue damage was calculated according to Miner’s linear cumulative damage law, and the reliability analysis was carried out using the Monte Carlo simulation method. The case results show that the fatigue life acquired by taking into account the cumulative effect of irradiation was reduced by 24.3% compared with that acquired without considering the irradiation effect. Irradiation led to the increase of the fatigue life at low strains and its decrease at high strains, which is in accordance with the findings of an irradiation fatigue test. The rate of increase in the fatigue life decreased gradually with the increase of the neutron dose. The irradiation performance parameters had a small influence on fatigue reliability, while the fatigue strength coefficient and the elastic modulus had a great influence on the fatigue reliability. Compared with the current method, which uses a high safety factor to determine design parameters, a fatigue reliability analysis method taking into account the cumulative effect of irradiation could be more accurate in the reliability analysis and life prediction of reactor structures.


2019 ◽  
Vol 10 (4) ◽  
pp. 454-468 ◽  
Author(s):  
Salvinder Singh ◽  
Shahrum Abdullah

Purpose The purpose of this paper is to present the durability analysis in predicting the reliability life cycle for an automobile crankshaft under random stress load using the stochastic process. Due to the limitations associated with the actual loading history obtained from the experimental analysis or due to the sensitivity of the strain gauge, the fatigue reliability life cycle assessment has lower accuracy and efficiency for fatigue life prediction. Design/methodology/approach The proposed Markov process embeds the actual maximum and minimum stresses by a continuous updating process for stress load history data. This is to reduce the large credible intervals and missing loading points used for fatigue life prediction. With the reduction and missing loading intervals, the accuracy of fatigue life prediction for the crankshaft was validated using the statistical correlation properties. Findings It was observed that fatigue reliability corresponded well by reporting the accuracy of 95–98 per cent with a mean squared error of 1.5–3 per cent for durability and mean cycle to failure. Hence, the proposed fatigue reliability assessment provides an accurate, efficient, fast and cost-effective durability analysis in contrast to costly and lengthy experimental techniques. Research limitations/implications An important implication of this study is durability-based life cycle assessment by developing the reliability and hazard rate index under random stress loading using the stochastic technique in modeling for improving the sensitivity of the strain gauge. Practical implications The durability analysis is one of the fundamental attributes for the safe operation of any component, especially in the automotive industry. Focusing on safety, structural health monitoring aims at the quantification of the probability of failure under mixed mode loading. In practice, diverse types of protective barriers are placed as safeguards from the hazard posed by the system operation. Social implications Durability analysis has the ability to deal with the longevity and dependability of parts, products and systems in any industry. More poignantly, it is about controlling risk whereby engineering incorporates a wide variety of analytical techniques designed to help engineers understand the failure modes and patterns of these parts, products and systems. This would enable the automotive industry to improve design and increase the life cycle with the durability assessment field focussing on product reliability and sustainability assurance. Originality/value The accuracy of the simulated fatigue life was statistically correlated with a 95 per cent boundary condition towards the actual fatigue through the validation process using finite element analysis. Furthermore, the embedded Markov process has high accuracy in generating synthetic load history for the fatigue life cycle assessment. More importantly, the fatigue reliability life cycle assessment can be performed with high accuracy and efficiency in assessing the integrity of the component regarding structural integrity.


1980 ◽  
Vol 47 (2) ◽  
pp. 324-328 ◽  
Author(s):  
Z. Hashin

It is shown that the simple Palmgren-Miner linear cumulative damage rule is a special case of a general cumulative damage theory previously established. Predictions of lifetimes for families of multistage loadings according to the Palmgren-Miner rule and the general cumulative damage theory are compared with the aim of arriving at qualitative guidelines for applicability of the Palmgren-Miner rule in cyclic loading programs.


2013 ◽  
Vol 652-654 ◽  
pp. 1357-1361 ◽  
Author(s):  
Fang Wei Zhao ◽  
Ji Long Xie ◽  
Yu Qing Yuan ◽  
Xiao Ling Shi

The load of C80B gondola freight car body is analyzed in railway. Measured load spectra of fatigue key parts of the freight car body are got. According to the measured load spectra, combined with the load-strain transfer coefficient, the fatigue damage of freight car body is calculated. Then fatigue life of C80B freight car body is predicted by using fatigue cumulative damage theory.


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