Hope College Department of Physics and Engineering Research Experiences for Undergraduates Summer 2004 Project Summary

Project Title: Effect of Stringer Dimensions on a Pre-Pressurized Blast-Loaded Aluminum Plate
Student Name: Courtney Clum
Student's home institution: Hope College
Research Advisor(s): Dr. Roger Veldman
Source of Support: NSF-REU

An aircraft is composed of riveted reinforcing stringers which form the internal frame and fuse the fuselage together. For aircraft structures there is no standard stringer geometry. Normally, one of two basic shapes, a Z-shape or hat-shape, is used in aircraft. Even given these two basic stringer shapes, the cross-sectional dimensions of the stringer vary from aircraft to aircraft.

Four stringer cross-sections were obtained from the following aircrafts: Airbus A300, Boeing 737, Boeing 747 and McDonnell Douglas DC-9. By calculating the moments of inertia for the four stringers, the stringers from the McDonnell Douglas DC-9 and the Boeing 747 were found to be the extreme cases.

A model of the aircraft fuselage was constructed by riveting two rows of stringers, composed of Aluminum 7076-T6, to Aluminum 2024-T3 panels (508.0 x 609.6 x 1.6256mm). Using the finite element method, plastic deformation could be determined for an unpressurized aluminum shell. Through this method it was found that the different stringer dimensions have a slight effect on the deformation of the skin under a blast loading. Additionally, through experiments, the stringer dimensions proved to have a small effect on the overall deformation, with the stiffer stringer allowing for less deformation.

The different stringers did not produce significantly different results; however, the stiffer of the two stringers did permit for less deformation in the fuselage under a blast. Although small, this slight difference in deformation could prevent the total failure of the aircraft structure, therefore signifying that stringer dimensions do play a small role in the deterrence of deformation under blast loading.