Mechanical Behavior comparison of aircraft joints modeling / Comparação de comportamento mecânico da modelagem de juntas de aeronaves

Abstract

The procedure of structural design for aircraft parts is widely known and discussed in the academy and in the industry, although it has been improved along the time. It is based on a detailed process of aerodynamics loads study coupled or not with specifications required by regulatory agencies. Further, several interactions of analysis are done to define the critical stress state of the structure submitted to load conditions, because it is a complex structure that needs to be often improved and updated (considering the requirement of assembly/disassembly simplicity). There are several components in an aircraft attached to each other by the use of fasteners, rivets or nuts made of different materials (aluminum, steel, Inconel among others). In fact, it is not to easy to obtain stress state of the aeronautical structure for real loading conditions. Further, it is also difficult to calculate the load acting on each one of the joints. Several studies were already performed in order to obtain the correct understanding of how actual loads is distributed through the joints. The present work aims to compare results in aircraft joints (focusing in spar and skin regions), considering three levels of fidelity to understand the differences in the structural response using different type of modeling approach. Finite Element Analysis modelings made using Nastran software were performed. Preliminary results show good response agreement even for high and intermediate detail levels. Low detail level present promisor response as a tool for predesign.