A simplified analysis of deflections in shear-deformable composite sandwich beams

Abstract

Simplified mechanics of materials equations for predicting both flexural and shear components of transverse deflections in composite sandwich beams are developed and validated by comparison with experimental measurements and finite element numerical predictions. Results are presented and compared for loading point deflections of two types of sandwich beams loaded in four-point bending; one having unidirectional carbon/ epoxy face sheets and a polymethacrylimide (PMI) foam core, and another having woven E-glass/epoxy face sheets and a PMI foam core. In both cases, shear deflections are greater than flexural deflections. The fraction of total deflection due to shear is greater for the beam with unidirectional carbon/epoxy face sheet than for the beam with woven E-glass/epoxy face sheets. Agreement between the current model predictions, experimental results, and finite element results is very good for the beams with unidirectional carbon/epoxy face sheets, and reasonably good for the beams with woven E-glass/epoxy face sheets.