Extreme Value Modeling and Parametric Investigations of Gust and Maneuver Loads for General Aviation

Abstract

An extreme value distribution (EVD) of the maximum load per flight of a load spectrum is critical for a probabilistic damage tolerance analysis of a General Aviation aircraft. The EVD parameters are important because the structural integrity of the aircraft depends upon the maximum load seen by the structure during a specified number of flights. It is well known that the load spectrum that an aircraft experiences depends upon a large number of variables including number of flights, type of usages, number of usages, percentage of each usage, maneuver and gust load limit factors, aircraft velocity, flight duration, ground stress, one-g-stress, exceedance curve, and randomness in these variables. This research investigates the effect of three selected variables (type of usage, exceedance curve, and flight length-velocity and flight length-weight matrices) on the maximum load per flight EVD. A computer code (load module) capable of generating a realistic load spectrum for a given set of loading parameters was developed. A generalized extreme value approach was developed to estimate the EVD of the maximum load per flight. A number of parametric investigations were performed to determine the effect of load spectrum variables on the EVD parameters. The preliminary results indicate that exceedance curves and type usage have the largest effect on the EVD parameters.