Standard Methods for Aerospace Stress Analysis

7Stress Evaluation Methods

7.1 Introduction to Stress Evaluation Methodology

This chapter tends to cover the stress evaluation methods of some of the main structural components in an aerospace structure. These structural elements are limited to skin membranes and plates, flat and curved long panels, flat and curved short panels, shear‐resistant beams, and beams under diagonal tension. Moreover, the fatigue and damage tolerance theory of the structural members is presented as well.

7.2 Structural Aspects of Design

7.2.1 Skin Membrane

For rectangular membrane shown in Figures 7.1 and 7.2, where a/b > 5 and the edge boundaries are either clamped on all four edges or only clamped along the long side of the membrane, the maximum stress and center deflection of the membrane under pressure, P, are given by:

(7.1)

(7.2)

where t is the membrane thickness, in., b is the width of the membrane, in., v is Poisson’s ratio, P is the applied pressure, psi, and E is the material’s elastic modulus, psi.

It should be noted that between the membrane with all edges clamped and the membrane with only long edges clamped, the deflections are approximately the same and can be calculated by equation (7.2).

Example

For a long rectangular membrane of 100 in. by 10 in., with a thickness of 0.1 in. ...