This article originally appeared in the September 1997 issue of Aviation Monthly newsletter and is reprinted here with permission of the publisher. Structural integrity is a major factor in aircraft design and construction. No production airplane leaves the ground before undergoing extensive analysis of how it will fly, the stresses it will tolerate and its maximum safe capability. Every airplane is subject to structural stress. Stress acts on an airplane whether on the ground or in flight.
Stress is defined as a load applied to a unit area of material.
Stress produces a deflection or deformation in the material called strain. Stress is always accompanied by strain. Current production general aviation aircraft are constructed of various materials, the primary being aluminum alloys. Rivets, bolts, screws and special bonding adhesives are used to hold the sheet metal in place. Regardless of the method of attachment of the material, every part of the fuselage must carry a load, or resist a stress placed on it.