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http://dx.doi.org/10.5762/KAIS.2020.21.6.448

A Study on the Cause and Improvement of Crack in the Installing Structure of the Bulkhead of Aircraft  

Choi, Hyoung Jun (Defense Agency for Technology and Quality)
Park, Sung Jae (Defense Agency for Technology and Quality)
Publication Information
Journal of the Korea Academia-Industrial cooperation Society / v.21, no.6, 2020 , pp. 448-454 More about this Journal
Abstract
This study aims to determine the cause of structural defects occurring during aircraft operations and to verify the structural integrity of the improved features. The fracture plane was analyzed to verify the characteristics of the cracks and the fatigue failure leading to the final fracture was determined by the progress of the cracks by the repeated load. During aircraft operations, the comparative analysis of the load measurement data at the cracks with the aircraft design load determined that the measured load was not at the level of 30% of the design to be capable of being damaged. A gap analysis resulted in a significant stress of approximately 32 ksi at the crack site. Pre-Load testing also confirmed that the M.S. was reduced by more than 50% from +0.71 to +0.43, resulting in a sharp increase in aircraft load and the possibility of cracking when combined. Thus, structural reinforcement and the removal of the gap for aircraft cracking sites improved the defect. Based on the structural strength analysis of the improvement features, the bulkhead has a margin of about +0.88 and the fitting feature is about +0.48 versus allowable stress. In addition, the life analysis results revealed an improvement of approximately 84000 hours.
Keywords
Structure Crack; Bulkhead; Pre-load; Structural Life Analysis; Fatigue;
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