Experimental and theoretical results for composite material I-beams

Abstract

This paper examines the loaddeflection behavior and the associated bending stiffness of graphite-epoxy I-beams. Some experimental results will be compared to an analyhcal theory based on lamination theory. The experimental results used locally fabricated I-beams. The fabrication technique is described. The beams studied consisted of several layers of T3001934 graphiteepoxy. Three configurations were used. The beams were subjected to three point loadings. The tests were short beam shear tests with span to depth ratios of 5 to 8. Load vs. deflection data were measured and recorded. The shear and bending deflection contributions were calculated using Timoshenko Beam Theory. Difficulties in separating the bending and shear deflections are discussed. The equivalent bending stiffness, Ed, was obtained from the bending deflection portion of the total deflection. The sensrhvrty of this calculation to errors in experimental measurements are discussed. Predictions of the bending stiffness are made using a method based on lamination theory., A comparison of results from this method with experimentally derived values for the configurations studied is also presented.