First, Wirsching's model, which is widely employed in fatigue reliability anlysis of marine and offshore structures, is analysed systematically. It is found that the very important random variable A in Wirsching&#...First, Wirsching's model, which is widely employed in fatigue reliability anlysis of marine and offshore structures, is analysed systematically. It is found that the very important random variable A in Wirsching's model can not be directly determined from fatigue experiment because of the irreversibility of fatigue test, and in fact, what Wirsching studied from testing results is not A but a of the statistical Miner's rule. Second, by use of the statistical Miner's rule, a modified Wirsching's model is proposed. Thirdly and more importantly, based on the two-dimensional probabilistic Miner's rule, a new model is established for fatigue reliability analysis of structural components subjected to specified cyclic loading of variable amplitude or stochastic time history. In the end, an example is presented, from which it will be seen that this new model is very convenient to use and feasible to engineering practice.展开更多
A fatigue damage model is developed for evaluating accumulative fatigue damage of dumpers. The loading spectrums acted on dumpers are created according to measured strain data in field. The finite element analysis is ...A fatigue damage model is developed for evaluating accumulative fatigue damage of dumpers. The loading spectrums acted on dumpers are created according to measured strain data in field. The finite element analysis is carried out for assessing stress distribution and strength characteristics of dumpers. Fatigue damage indexes and service life are calculated by a modified Palmgren-Miner rule. The investigation shows that fatigue notch factor has a significant influence on the calculation of fatigue damage of dumpers.展开更多
Firstly, constant amplitude P-S_a-S_m-N_c surface family is established.Secondly, four basic assumptions, i.e., monotonically increasing, non-coupling, separability andnonintersecting of fatigue damage accumulation ar...Firstly, constant amplitude P-S_a-S_m-N_c surface family is established.Secondly, four basic assumptions, i.e., monotonically increasing, non-coupling, separability andnonintersecting of fatigue damage accumulation are proposed from the viewpoint of both damagemechanics and fracture mechanics. Then the individual isodamage D-S_a-S_m-N surface under constantamplitude loading is constructed and the two-dimensional individual Miner's rule is derived.Consequently, the two-dimensional probabilistic Miner's rule (TPMiner) is established and proved fora population subjected to variable amplitude loading. Finally, with successfully experimentverification, TPMiner proves be to very useful and feasible in fatigue reliability theory.展开更多
In the confined spaces of underground mines,the exposure of over 10,000 miners in the U.S.to diesel exhaust and diesel particulate matter(DPM)is an occupational inevitability,particularly in metal and nonmetal mineral...In the confined spaces of underground mines,the exposure of over 10,000 miners in the U.S.to diesel exhaust and diesel particulate matter(DPM)is an occupational inevitability,particularly in metal and nonmetal mineral extraction.These workers routinely operate amidst diesel-powered equipment,often outdated and highly polluting,extracting resources such as limestone,gold,and salt.The acute health effects of such exposure are significant,leading to symptoms like headaches and flu-like conditions,with the impact being more pronounced in these closed work environments.This review scrutinizes DPM's hazard in the mining sector,consolidating the extant knowledge and exploring ongoing research.It encapsulates our understanding of DPM's physicochemical properties,existing sampling methods,health ramifications,and mitigation technologies.Moreover,it underscores the necessity for further study in areas such as the evolution of DPM's physicochemical attributes,from its genesis at high-pressure,high-temperature conditions within diesel engines to its emission into the mine atmosphere.A key research gap is the intricate interaction of DPM with specific characteristics of the mine environment-such as relative humidity,ambient temperature,the presence of other mineral dust,and the dynamics of ventilation air.These factors can significantly alter the physicochemical profile of DPM,infuencing both its in-mine transport and its deposition behavior.Consequently,this can affect the respiratory health of miners,modifying the toxicity and the respiratory deposition of DPM particles.Identified research imperatives include(1)the advancement of instrumentation for accurate number measurement of DPM to replace or supplement traditional gravimetric methods;(2)the development of long-lasting,cost-effective control technologies tailored for the mining industry;(3)an in-depth investigation of DPM interactions within the unique mine microclimate,considering the critical components like humidity and other aerosols;and(4)understanding the differential impact of DPM in mining compared to other industries,informing the creation of mining-specific health and safety protocols.This review's findings underscore the urgency to enhance emission control and exposure prevention strategies,paving the way for a healthier underground mining work environment.展开更多
in reliability design of fatigue under random loading, the influence of loading se-quence must be considered. In order to avoid the uneertain hypothesis in the Miner's rule, ie. thatthe sum of damage equals one re...in reliability design of fatigue under random loading, the influence of loading se-quence must be considered. In order to avoid the uneertain hypothesis in the Miner's rule, ie. thatthe sum of damage equals one represents failure, this paper proposes the probabilistic relativeMine's rule. This paper also presents a new method for calculating reliability, ie. the syntheticmethod of Miner's rule and interference model. This model considers not only the influence ofstress concentration, dimension and surface, but also the influence of stress amplitude and se-quence.展开更多
基金This project was financially supported by the National Science Foundation of China(59605010)and the Postdoctoral Science Foundation of China
文摘First, Wirsching's model, which is widely employed in fatigue reliability anlysis of marine and offshore structures, is analysed systematically. It is found that the very important random variable A in Wirsching's model can not be directly determined from fatigue experiment because of the irreversibility of fatigue test, and in fact, what Wirsching studied from testing results is not A but a of the statistical Miner's rule. Second, by use of the statistical Miner's rule, a modified Wirsching's model is proposed. Thirdly and more importantly, based on the two-dimensional probabilistic Miner's rule, a new model is established for fatigue reliability analysis of structural components subjected to specified cyclic loading of variable amplitude or stochastic time history. In the end, an example is presented, from which it will be seen that this new model is very convenient to use and feasible to engineering practice.
文摘A fatigue damage model is developed for evaluating accumulative fatigue damage of dumpers. The loading spectrums acted on dumpers are created according to measured strain data in field. The finite element analysis is carried out for assessing stress distribution and strength characteristics of dumpers. Fatigue damage indexes and service life are calculated by a modified Palmgren-Miner rule. The investigation shows that fatigue notch factor has a significant influence on the calculation of fatigue damage of dumpers.
基金This project is supported by National Natural Science Foundation of China(No.59605010,No.59979015)Selected from Proceedings of 2000 the First International Conference on Mechanical Engineering
文摘Firstly, constant amplitude P-S_a-S_m-N_c surface family is established.Secondly, four basic assumptions, i.e., monotonically increasing, non-coupling, separability andnonintersecting of fatigue damage accumulation are proposed from the viewpoint of both damagemechanics and fracture mechanics. Then the individual isodamage D-S_a-S_m-N surface under constantamplitude loading is constructed and the two-dimensional individual Miner's rule is derived.Consequently, the two-dimensional probabilistic Miner's rule (TPMiner) is established and proved fora population subjected to variable amplitude loading. Finally, with successfully experimentverification, TPMiner proves be to very useful and feasible in fatigue reliability theory.
基金supported by The National Institute of Occupational Safety and Health(NIOSH)under contract No.75D30119C05743.
文摘In the confined spaces of underground mines,the exposure of over 10,000 miners in the U.S.to diesel exhaust and diesel particulate matter(DPM)is an occupational inevitability,particularly in metal and nonmetal mineral extraction.These workers routinely operate amidst diesel-powered equipment,often outdated and highly polluting,extracting resources such as limestone,gold,and salt.The acute health effects of such exposure are significant,leading to symptoms like headaches and flu-like conditions,with the impact being more pronounced in these closed work environments.This review scrutinizes DPM's hazard in the mining sector,consolidating the extant knowledge and exploring ongoing research.It encapsulates our understanding of DPM's physicochemical properties,existing sampling methods,health ramifications,and mitigation technologies.Moreover,it underscores the necessity for further study in areas such as the evolution of DPM's physicochemical attributes,from its genesis at high-pressure,high-temperature conditions within diesel engines to its emission into the mine atmosphere.A key research gap is the intricate interaction of DPM with specific characteristics of the mine environment-such as relative humidity,ambient temperature,the presence of other mineral dust,and the dynamics of ventilation air.These factors can significantly alter the physicochemical profile of DPM,infuencing both its in-mine transport and its deposition behavior.Consequently,this can affect the respiratory health of miners,modifying the toxicity and the respiratory deposition of DPM particles.Identified research imperatives include(1)the advancement of instrumentation for accurate number measurement of DPM to replace or supplement traditional gravimetric methods;(2)the development of long-lasting,cost-effective control technologies tailored for the mining industry;(3)an in-depth investigation of DPM interactions within the unique mine microclimate,considering the critical components like humidity and other aerosols;and(4)understanding the differential impact of DPM in mining compared to other industries,informing the creation of mining-specific health and safety protocols.This review's findings underscore the urgency to enhance emission control and exposure prevention strategies,paving the way for a healthier underground mining work environment.
文摘in reliability design of fatigue under random loading, the influence of loading se-quence must be considered. In order to avoid the uneertain hypothesis in the Miner's rule, ie. thatthe sum of damage equals one represents failure, this paper proposes the probabilistic relativeMine's rule. This paper also presents a new method for calculating reliability, ie. the syntheticmethod of Miner's rule and interference model. This model considers not only the influence ofstress concentration, dimension and surface, but also the influence of stress amplitude and se-quence.
