Computational method for load enhancement factors and apparatus for executing same
First Claim
1. A method of calculating a Load Enhancement Factor using Modified Joint Weibull Analysis, comprising the method steps of:
- retrieving a data set from an at least one database;
analyzing the data retrieved for fit with a statistical distribution model;
analyzing the data retrieved for statistical conditions;
calculating a stress to life cycle relationship accounting for scatter in the test data; and
calculating a Load Enhancement Factor based on the stress to life cycle relationship.
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Abstract
A method and computer system for executing a program for calculating Load Enhancement Factor that includes the steps of obtaining coupon test data and storing the coupon test data on an information storage device. Analyzing the coupon test data for fit with a Weibull distribution and other analysis criteria and performing either a Modified Joint Weibull analysis or a Weibull Regression analysis or both a Modified Joint Weibull analysis and a Weibull Regression analysis with an accommodation in the analysis for scatter within the coupon testing data.
5 Citations
40 Claims
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1. A method of calculating a Load Enhancement Factor using Modified Joint Weibull Analysis, comprising the method steps of:
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retrieving a data set from an at least one database; analyzing the data retrieved for fit with a statistical distribution model; analyzing the data retrieved for statistical conditions; calculating a stress to life cycle relationship accounting for scatter in the test data; and calculating a Load Enhancement Factor based on the stress to life cycle relationship.
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2. A method of computing at least one of a Load Factor, a Life Factor and a Load Enhancement Factor using Modified Joint Weibull Analysis, comprising the method steps of:
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retrieving a test data set from an at least one database; analyzing the data retrieved for fit with a Weibull distribution model for the data; analyzing the test data set retrieved to determine if at least two coupons have been tested and if both the applied loads and duration of testing at the component-level were varied; computing an at least one shape parameter for the Weibull distribution model and storing the at least one shape parameter; computing an at least one scale parameter for the Weibull distribution of the data and storing the at least one scale parameter; computing a stress to life cycle relationship accounting for scatter in the data through the Weibull distribution data; and computing the at least one of a Life Factor, a Load Factor and a Load Enhancement Factor based on the stress to life cycle relationship from the computed stress to life cycle relationship, thereby accounting for scatter in the at least one Life Factor, a Load Factor and a Load Enhancement Factor. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method of calculating a Load Enhancement Factor using Weibull Regression Analysis, comprising the method steps of:
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obtaining coupon test data; applying a Weibull distribution regression function to the coupon test data to develop an estimated stress to fatigue life curve and applying an equation to relate the log of a scale parameter of the Weibull distribution regression function with the log of a stress level of the stress to fatigue life curve; implementing an estimation procedure to incorporate the stress to fatigue life relationship in the computation of the Load Enhancement Factor through the intercept and slope of the estimates of the stress to fatigue life curve ({circumflex over (θ
)}0,{circumflex over (θ
)}1); andobtaining a confidence level and using a variance and a co-variance matrix developed from the estimation procedure to compute the Load Enhancement Factor. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method of certifying an aircraft that includes a composite component, the method comprising:
calculating a Load Enhancement Factor using Modified Joint Weibull Analysis, wherein calculating the Load Enhancement Factor comprises the steps of; retrieving a data set from an at least one database; analyzing the data retrieved for fit with a statistical distribution model; analyzing the data retrieved for statistical conditions; calculating a stress to life cycle relationship accounting for scatter in the test data; and calculating a Load Enhancement Factor based on the stress to life cycle relationship.
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39. A method of evaluating a composite component of an aircraft, the method comprising:
calculating a Load Enhancement Factor using Modified Joint Weibull Analysis, wherein calculating the Load Enhancement Factor comprises the steps of; retrieving a data set from an at least one database; analyzing the data retrieved for fit with a statistical distribution model; analyzing the data retrieved for statistical conditions; calculating a stress to life cycle relationship accounting for scatter in the test data; and calculating a Load Enhancement Factor based on the stress to life cycle relationship.
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40. A computer system operating a computer program for calculating a Load Enhancement Factor, comprising:
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obtaining coupon test data; storing said coupon test data on an information storage device; a program segment analyzing said coupon test data for fit to a Weibull distribution, the program ending in response to the coupon test data not fitting a Weibull distribution; a program segment analyzing said coupon test data to determine if a single stress level was tested in the coupon test data; a program segment determining if sufficient runout data is available if the step for analyzing the coupon test data for a single stress level is positive, and if the step of determining sufficient runout is available is negative, ending the program; determining if sufficient static strength data is available in the coupon test data if the method step of determining if sufficient runout data is affirmative, and if the step of determining if sufficient static strength data is available is negative executing a Modified Joint Weibull Analysis code segment; executing at least one of a Modified Joint Weibull Analysis code segment and a Weibull Regression code segment with static strength if the method step of determining if sufficient static strength data is affirmative; determining if a single replicate is available/was tested if the step for analyzing the coupon test data for a single stress level is negative, and if a determination is made that a single replicate was tested executing a Weibull regression code segment; a program segment determining if sufficient runout data is available if the step of determining if a single replicate is available/was tested is negative, and if a determination is made that sufficient runout is not available, ending the computer program; and determining if sufficient static strength data is available if the method step of determining if sufficient runout data is available is affirmative, and if the step of determining if sufficient static strength data is available is positive, executing at least one of a Modified Joint Weibull code segment and an at least one Weibull Regression Analysis code segment with static strength computations to compute an LEF and if the step of determining if sufficient static strength data is available is negative, executing at least one of a Modified Joint Weibull code segment and an at least one Weibull Regression Analysis code segment without static strength computations.
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Specification