SEDL / STP / STP617-EB / STP26948S

Empirical Crippling Analysis of Graphite/Epoxy Laminated Plates

Spier, EE
Design specialist, General Dynamics Convair Division, San Diego, Calif.

Klouman, FL
Research engineer, The Norwegian Defense Research Establishment, Kjeller,

Pages: 17    Published: Jan 1977

Download this paper for $25 PDF (280K)          View License Agreement
Abstract

This paper is concerned with developing empirical crippling curves for A-S/3501 graphite/epoxy laminated plates to use in analyzing the buckling behavior of stiffened plates. The cross sections of the stiffeners are restricted to flat plate elements, where either both unloaded edges are simply supported or one of the unloaded edges is simply supported and the other edge is free. Laminates tested are of the type [±45^A/0^B/∓45^A]^T for B/A ratios of 2, 4, and 6, which include the spectrum of most stiffener designs. Evidence shows that the laminates selected are superior to laminates of the type [0^B/2/±45^A]^S. Crippling curves are presented in nondimensional form, which are particularly useful for estimating crippling strengths of similar graphite/epoxy systems. Corresponding buckling curves plotted along with the crippling curves show that theoretical elastic buckling theory is not adequate for predicting the ultimate compressive strength of composite laminated plates. Ultimate compression tests were performed to establish upper limit cutoff stresses for the crippling curves.