Verification of principles for design of composite material I-Beams

This paper is a summary of work done in fulfillment of a Senior Honors Project. This paper details design, manufacture and testing of composite I-beams (AS4/3501-6 carbon/epoxy laminate). Two types of I-beam specimens were constructed: a symmetric I-beam with a web and flange thickness of six plies and a similar specimen but with a nonsymmetric cross-section having one of the flanges reinforced with 18 additional plies. The I-beams were tested in 4-point bending to failure. Experimental results were compared with predicted analytical theory. The predicted failure mode was assumed to be flange failure by axial forces caused by 4-point bending. Actually, two unexpected failure modes occurred. Buckling occurred in the web and the compression flange of the I-beams with symmetric cross-sections. In the other specimens with nonsymmetric cross-sections, it was concluded that the failure mode was compressive failure in the web.