Many commercial aircraft are designed so that fuselage skins can elastically buckle below a limit load and continue to operate safely and efficiently, which leads to a lighter structure than a non-buckling design. The analysis of post-buckling behavior, which is called intermediate diagonal tension (IDT), is critical to design such structures.

This analysis is currently carried out by OEMs using semi-empirical methods with hand and spreadsheet calculations. These methods are reliable but overly conservative, which leads to sub-optimum and heavier designs. However, weight is a critical factor when designing aircrafts because it has a significant influence on performance and operation economy.

This series of paper is trying to construct a simulation-based design and optimization methodology for IDT structures, which helps engineers to design these structures lighter while maintaining all necessary safety requirements. This is the second paper of the series about post-buckling analysis and optimization methodology. More background information can be found in the previous paper of the series.