EXPERIMENTAL EVALUATION OF STIFFNESS OF LAMINATED COMPOSITE BEAM ELEMENTS UNDER FLEXURE

The objectives of this study are: (1) to define upper and lower bounds for the stiffness of laminated beam elements under flexure, (2) to co rrelate experimental effective beam moduli with analytical predictions , and (3) to obtain a threshold aspect-ratio that limits the range of application of various analytic methods. Experimental tests were condu cted to characterize the load-displacement response of laminated beam elements under flexure, and the results were correlated with available analytic approaches. Angle-ply laminated beam elements were chosen to distinctly show the differences between various analytic methods. Thr ee-point bending tests were performed, both flatwise (out-of-plane) an d edgewise (in-plane), on rectangular lay-up specimens made of AS-4/35 01-6 carbon-epoxy. Recommendations are made for the analytical predict ion of stiffness under various conditions.