Based on probabilistic fracture mechanics approach, a new concept of material initial fatigue quality （MIFQ） is developed. Then, the relation between S-N curve and crack propagation curve is studied. From the study,...Based on probabilistic fracture mechanics approach, a new concept of material initial fatigue quality （MIFQ） is developed. Then, the relation between S-N curve and crack propagation curve is studied. From the study, a new durability analysis method is presented. In this method, S-N curve is used to determine crack growth rate under constant amplitude loading and evaluate the effects of different factors on durability and then the structural durability is analyzed. The tests and analyses indicate that this method has lower dependence on testing, and higher accuracy, reliability and generality and is convenient for application.展开更多
When the historic probabilistic S-N curves are given under special survival probability and confidence levels and there is no possible to re-test, fatigue reliability analysis at other levels can not be done except fo...When the historic probabilistic S-N curves are given under special survival probability and confidence levels and there is no possible to re-test, fatigue reliability analysis at other levels can not be done except for the special levels. Therefore, the wide applied curves are expected. Monte Carlo reconstruction methods of the test data and the curves are investigated under fatigue life following lognormal distribution. To overcome the non-conservative assessment of existent man-made enlarging the sample size up to thousands, a simulation policy is employed to address the true production where the sample size is controlled less than 20 for material specimens, 10 for structural component specimens and the errors matching the statistical parameters are less than 5 percent. Availability and feasibility of the present methods have been indicated by the reconstruction practice of the test data and curves for 60Si2Mn high strength spring steel of railway industry.展开更多
In this paper, we study a new method in shape adjustment ofS-λcurves. By examples of finite and infinite degree generation function, we get the conclusion thatS-λcurves can be adjusted by perturbation of generation ...In this paper, we study a new method in shape adjustment ofS-λcurves. By examples of finite and infinite degree generation function, we get the conclusion thatS-λcurves can be adjusted by perturbation of generation functionS（t）while the control points and parameters hold.展开更多
This paper applies weighted least square method to estimate the three-parameter power function equation of the fatigue life curve, and uses comprehensive fatigue life coefficient to correct the equation, and at the sa...This paper applies weighted least square method to estimate the three-parameter power function equation of the fatigue life curve, and uses comprehensive fatigue life coefficient to correct the equation, and at the same time combines probability statistics method to bring out the prediction method of structure＇s three- parameter power function P-S-N curve, finally applies the prediction method to a ship＇s frame-type elevate, based on the fatigue test data of it＇s material-SA06 aluminium alloy, to obtain it＇s structure＇s three-parameter power function P-S-N curve. Compared with the conventional least square method, the presented method can give展开更多
Due to continuous scaling of CMOS, stability is a prime concerned for CMOS SRAM memory cells. As scaling will increase the packing density but at the same time it is affecting the stability which leads to write failur...Due to continuous scaling of CMOS, stability is a prime concerned for CMOS SRAM memory cells. As scaling will increase the packing density but at the same time it is affecting the stability which leads to write failures and read disturbs of the conventional 6T SRAM cell. To increase the stability of the cell various SRAM cell topologies has been introduced, 8T SRAM is one of them but it has its limitation like read disturbance. In this paper we have analyzed a novel PP based 9T SRAM at 45 nm technology. Cell which has 33% increased SVNM (Static Voltage Noise Margin) from 6T and also 22%.reduced leakage power. N curve analysis has been done to find the various stability factors. As compared to the 10T SRAM cell it is more area efficient.展开更多
In this paper, the generator set of R 〈 x1,x2 〉G is obtained in according to the group G = Gl（n,R）. The conditions of G = Gl（n, R） -equivalence of a pair of curves are found in terms of G = Gl（n, R）-invariants...In this paper, the generator set of R 〈 x1,x2 〉G is obtained in according to the group G = Gl（n,R）. The conditions of G = Gl（n, R） -equivalence of a pair of curves are found in terms of G = Gl（n, R）-invariants. And the independence of GL（n, R） -invariants is shown.展开更多
基金National Natural Science Foundation of China (60472118) High-tech Research Project of Jiangsu Province (BG2004008)
文摘Based on probabilistic fracture mechanics approach, a new concept of material initial fatigue quality （MIFQ） is developed. Then, the relation between S-N curve and crack propagation curve is studied. From the study, a new durability analysis method is presented. In this method, S-N curve is used to determine crack growth rate under constant amplitude loading and evaluate the effects of different factors on durability and then the structural durability is analyzed. The tests and analyses indicate that this method has lower dependence on testing, and higher accuracy, reliability and generality and is convenient for application.
基金Project supported by the National High Technology Research and Development Program of China(863 Program) (No.2006AA04Z406)the National Natural Science Foundation of China (Nos.50375130, 50323003 and 50575189)+1 种基金the Special Foundation for the Authors of National Excellent Doctoral Dissertations (No.200234)the Program for New Century Excellent Talents in University(No.NCET040890)
文摘When the historic probabilistic S-N curves are given under special survival probability and confidence levels and there is no possible to re-test, fatigue reliability analysis at other levels can not be done except for the special levels. Therefore, the wide applied curves are expected. Monte Carlo reconstruction methods of the test data and the curves are investigated under fatigue life following lognormal distribution. To overcome the non-conservative assessment of existent man-made enlarging the sample size up to thousands, a simulation policy is employed to address the true production where the sample size is controlled less than 20 for material specimens, 10 for structural component specimens and the errors matching the statistical parameters are less than 5 percent. Availability and feasibility of the present methods have been indicated by the reconstruction practice of the test data and curves for 60Si2Mn high strength spring steel of railway industry.
基金Supported by National Natural Science Foundation of China(No.61170324 and No.61100105)
文摘In this paper, we study a new method in shape adjustment ofS-λcurves. By examples of finite and infinite degree generation function, we get the conclusion thatS-λcurves can be adjusted by perturbation of generation functionS（t）while the control points and parameters hold.
文摘This paper applies weighted least square method to estimate the three-parameter power function equation of the fatigue life curve, and uses comprehensive fatigue life coefficient to correct the equation, and at the same time combines probability statistics method to bring out the prediction method of structure＇s three- parameter power function P-S-N curve, finally applies the prediction method to a ship＇s frame-type elevate, based on the fatigue test data of it＇s material-SA06 aluminium alloy, to obtain it＇s structure＇s three-parameter power function P-S-N curve. Compared with the conventional least square method, the presented method can give
文摘Due to continuous scaling of CMOS, stability is a prime concerned for CMOS SRAM memory cells. As scaling will increase the packing density but at the same time it is affecting the stability which leads to write failures and read disturbs of the conventional 6T SRAM cell. To increase the stability of the cell various SRAM cell topologies has been introduced, 8T SRAM is one of them but it has its limitation like read disturbance. In this paper we have analyzed a novel PP based 9T SRAM at 45 nm technology. Cell which has 33% increased SVNM (Static Voltage Noise Margin) from 6T and also 22%.reduced leakage power. N curve analysis has been done to find the various stability factors. As compared to the 10T SRAM cell it is more area efficient.
文摘In this paper, the generator set of R 〈 x1,x2 〉G is obtained in according to the group G = Gl（n,R）. The conditions of G = Gl（n, R） -equivalence of a pair of curves are found in terms of G = Gl（n, R）-invariants. And the independence of GL（n, R） -invariants is shown.
