Fatigue failure of mechanical part is treated as a random event.the fatigue reliablility problem can be solved through researching the random event.A new definition δb that measures fatigue damage quantity in a cycle...Fatigue failure of mechanical part is treated as a random event.the fatigue reliablility problem can be solved through researching the random event.A new definition δb that measures fatigue damage quantity in a cycle under cyclic stress is put forward. According to δ.the paper presents two new definitions K and D is fatigue damage strength.D is overall fatigue damage quantity.Using K and D to describe the fatigue failure of the parts,the paper puts forward a new fatigue cumulative damage probabilistic model of the mechanical parts.The model can be used to solve reliability fatigue problem.展开更多
Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic load...Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.展开更多
In this paper,stress states under corresponding condition of an aero-engine fan blade using finite element stress-strain analysis for three work cycles in the 900 h load spectrum are obtained.Through the nominal stres...In this paper,stress states under corresponding condition of an aero-engine fan blade using finite element stress-strain analysis for three work cycles in the 900 h load spectrum are obtained.Through the nominal stress method,we calculated the fatigue notch factor and combined the material characteristics of TC6 to correct the material curve to the fan blades curve. Finally,the fatigue life of a fan blade was estimated using the linear cumulative damage rule and nonlinear cumulative damage theory.展开更多
The procedure of reliability-based fatigue analysis of liquefied natural gas(LNG) carrier of membrane type under wave loads is presented. The stress responses of the hotspots in regular waves with different wave headi...The procedure of reliability-based fatigue analysis of liquefied natural gas(LNG) carrier of membrane type under wave loads is presented. The stress responses of the hotspots in regular waves with different wave heading angles and wave lengths are evaluated by global ship finite element method(FEM) . Based on the probabilistic distribution function of hotspots' short-term stress-range using spectral-based analysis,Weibull distribution is adopted and discussed for fitting the long-term probabilistic distribution of stress-range. Based on linear cumulative damage theory,fatigue damage is characterized by an S-N relationship,and limit state function is established. Structural fatigue damage behavior of several typical hotspots of LNG middle ship section is clarified and reliability analysis is performed. It is believed that the presented results and conclusions can be of use in calibration for practical design and initial fatigue safety evaluation for membrane type LNG carrier.展开更多
Based on the theoretical inference and experiment verification,a method was proposed to carry out the accelerated reliability qualification testing. First,theoretical inference was used to get the acceleration coeffic...Based on the theoretical inference and experiment verification,a method was proposed to carry out the accelerated reliability qualification testing. First,theoretical inference was used to get the acceleration coefficients of super Gauss vibration stress and temperature stress. Then, by applying these coefficients, an accelerated reliability qualification testing curve was obtained from the standard tests. Finally,the actual experiment on a digital marine control device was carried out under the proposed testing method.The experiment result shows that the proposed method can reduce the total experiment time and improve the efficiency of the reliability qualification test.展开更多
Flange joint part is the weak link of wind turbine tower.In view of the special structure,complex stress and easy failure of the connecting bolt of the wind turbine tower flange,the relationship between the external l...Flange joint part is the weak link of wind turbine tower.In view of the special structure,complex stress and easy failure of the connecting bolt of the wind turbine tower flange,the relationship between the external load of the tower section and the internal stress of the bolt is established by the finite element method,and the time series internal stress of the bolt is calculated by the Schmidt-Neuper algorithm.The S-N curve which is suitable for the connecting bolt material of the tower flange is selected by the GL2010 specification.On the basis of Miner’s fatigue cumulative damage theory and rain flow counting method,the fatigue strength of the whole ring bolt is roughly calculated,and the most dangerous part is determined.The axial symmetry model of screw connection is used for accurately calculating the fatigue cumulative damage of the bolt at the dangerous part.The results show that the fatigue life of the bolts in the most dangerous position can meet the requirements,the engineering algorithm has advantages in determining the dangerous part of the whole ring bolt,and the finite element method has high accuracy in predicting the fatigue life of the bolts in the dangerous part.The proposed method is feasible and effective in predicting the fatigue life of the flange joint bolts of the tower.展开更多
文摘Fatigue failure of mechanical part is treated as a random event.the fatigue reliablility problem can be solved through researching the random event.A new definition δb that measures fatigue damage quantity in a cycle under cyclic stress is put forward. According to δ.the paper presents two new definitions K and D is fatigue damage strength.D is overall fatigue damage quantity.Using K and D to describe the fatigue failure of the parts,the paper puts forward a new fatigue cumulative damage probabilistic model of the mechanical parts.The model can be used to solve reliability fatigue problem.
基金supported by the National Natural Science Foundation of China(No.10377007)
文摘Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.
文摘In this paper,stress states under corresponding condition of an aero-engine fan blade using finite element stress-strain analysis for three work cycles in the 900 h load spectrum are obtained.Through the nominal stress method,we calculated the fatigue notch factor and combined the material characteristics of TC6 to correct the material curve to the fan blades curve. Finally,the fatigue life of a fan blade was estimated using the linear cumulative damage rule and nonlinear cumulative damage theory.
文摘The procedure of reliability-based fatigue analysis of liquefied natural gas(LNG) carrier of membrane type under wave loads is presented. The stress responses of the hotspots in regular waves with different wave heading angles and wave lengths are evaluated by global ship finite element method(FEM) . Based on the probabilistic distribution function of hotspots' short-term stress-range using spectral-based analysis,Weibull distribution is adopted and discussed for fitting the long-term probabilistic distribution of stress-range. Based on linear cumulative damage theory,fatigue damage is characterized by an S-N relationship,and limit state function is established. Structural fatigue damage behavior of several typical hotspots of LNG middle ship section is clarified and reliability analysis is performed. It is believed that the presented results and conclusions can be of use in calibration for practical design and initial fatigue safety evaluation for membrane type LNG carrier.
文摘Based on the theoretical inference and experiment verification,a method was proposed to carry out the accelerated reliability qualification testing. First,theoretical inference was used to get the acceleration coefficients of super Gauss vibration stress and temperature stress. Then, by applying these coefficients, an accelerated reliability qualification testing curve was obtained from the standard tests. Finally,the actual experiment on a digital marine control device was carried out under the proposed testing method.The experiment result shows that the proposed method can reduce the total experiment time and improve the efficiency of the reliability qualification test.
基金the Special Research Fund for the Natural Science Foundation of Inner Mongolia Autonomous Region(No.2019MS05070)。
文摘Flange joint part is the weak link of wind turbine tower.In view of the special structure,complex stress and easy failure of the connecting bolt of the wind turbine tower flange,the relationship between the external load of the tower section and the internal stress of the bolt is established by the finite element method,and the time series internal stress of the bolt is calculated by the Schmidt-Neuper algorithm.The S-N curve which is suitable for the connecting bolt material of the tower flange is selected by the GL2010 specification.On the basis of Miner’s fatigue cumulative damage theory and rain flow counting method,the fatigue strength of the whole ring bolt is roughly calculated,and the most dangerous part is determined.The axial symmetry model of screw connection is used for accurately calculating the fatigue cumulative damage of the bolt at the dangerous part.The results show that the fatigue life of the bolts in the most dangerous position can meet the requirements,the engineering algorithm has advantages in determining the dangerous part of the whole ring bolt,and the finite element method has high accuracy in predicting the fatigue life of the bolts in the dangerous part.The proposed method is feasible and effective in predicting the fatigue life of the flange joint bolts of the tower.
