Many commercial aircraft are designed such that fuselage skin panels can elastically buckle below limit load and still continue to operate safely and efficiently. This buckled skin and subsequent redistribution of internal load leads to a lighter structure than a non-buckling design. The analysis of this post-buckling behavior is called intermediate diagonal tension (IDT). This analysis is currently carried out by OEMs using semi-empirical methods with hand and spreadsheet calculations. These methods are reliable but can be overly conservative leading to suboptimal and heavier designs. Since weight is such an important factor when designing aircraft, it would be valuable to have an IDT method which produces a more optimized and lighter design than present methods.

This series of papers is constructing a simulation-based design and optimization methodology for IDT structures, which helps engineers design lighter structures while maintaining all necessary safety requirements. This is the third paper of the series about post-buckling analysis and optimization methodology. More background information can be found in the previous paper “Intermediate Diagonal Tension (IDT) Beam Analysis and Test Comparison”.