The Study Of Parameter Determination Of Domestic Materials DFR Method By3-Weibull Distribution

Detail fatigue rating (DFR) is one of the civil aircraft structural fatigue lifereliability analysis method based on the probability of fatigue. This method has alarger development at home and abroad, with the development and wide applicationof DFR method，the problem of weather the material meets the parameters of foreignDFR method needs to be resolved. With the continuous development of computertechnology allows the introduction of the three-parameter Weibull distribution ofDFR for statistical computing possible. The introduction of the three-parameterWeibull distribution in the design will be able to more fully exploit the characteristicsof the material, under certain structural design makes life more economical andreasonable.Determination of various domestic aluminum paper, titanium alloy, highstrength steel material fatigue life data in a large sample life in the104to106range.Collected3material test data of aluminum,titanium,and high strength steel category.Establish a method to calculate the shape parameters,Partially range of domesticmaterials shape parameters and values for comparison with Boeing, the shapeparameter is less than the recommended value of domestic materials Boeing.According to the defination of DFR, establish the statistical analysis modelDFR(α), propose the quantitative analysis that α which is based on computersimulations of random value changes on DFR values.By studying the shapeparameter affecting the influence of DFR values are given for different values ofDFR allowable variation range of α design allowable value.Paper through experiment of12groups of205aluminum alloy specimen wastested, the fatigue life distribution of each specimen. The position parameters of theabove data in three parameter Weibull distribution statistical computing, by using thelinear regression method to analyze each fatigue life.The paper Studied the effects ofpositional parameters to shape parameter and get the position of each data allowable values. For different using state of the same material, the position parameter selectionare also different.