This research is an effort to understand the methodologies to develop flight-by-flight stress spectrum for the structural life assessment of aging or legacy aircrafts which have insufficient design information and data. Initially, the comprehensive study to understand the aircraft's general structural life assessment process was completed, especially about F-16 Block 32 aircraft which was developed by Lockheed Martin Aeronautics Company (LM Aero), US. From this study, it was found that developing stress spectrum is the most important part in the aircraft's structural life assessment process. In developing stress spectrum, there are two big challenges. One is developing a full scale finite element model to analyze the internal loads of the airframes, and the other is to calculate the external loads which will be applied on the full scale finite element model. During the aircraft design, developing the full scale FE model and external load data requires large amount of manpower and computing assistances. In the case of legacy aircraft, it is not easy to find these full scale FE models and external load data and one needs a budget for developing these. In this study, to solve this problem, the idealized and simplified full scale FE model is suggested and an alternative approach was used for calculating external load data. After performing internal load analyses using this full scale FE model and external loads, the stress equation of the control point, which is regarded as the fracture critical location of aircraft structures, is derived using the regression method based on the stress analysis results. Additionally, stress sensitivity analyses are performed to check the influence of geometric dimensional errors due to the idealization of a full scale finite element model.
The results of this research can contribute to the aging and legacy aircraft's structural life assessment, which could not expect design data from the load and stress analyses results, by suggesting simple and economical method for developing the stress spectrum.
|Commitee:||Cho, Sungdai, Ke, Changhong, Lu, Shuxia, McGrann, Roy T. R.|
|School:||State University of New York at Binghamton|
|School Location:||United States -- New York|
|Source:||DAI-B 74/07(E), Dissertation Abstracts International|
|Keywords:||Aircraft structural life assessment, Asip, Finite element analysis, Load spectrum, Stress analysis, Stress spectrum|
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