Effects of Face and Core Materials on Mechanical Properties of Sandwich Composite Beam under Four Point Bending Loading.

Abstract

The bending properties of sandwich composite beams under static and cyclic loadings were investigated. The sandwich beam consists of hard urethane foam core and GFRP surface plates. Four-point bending tests were conducted to examine the effects of facing plate thickness and core rigidity on the flexural properties under static and cyclic loadings. The experimental results reveal that : (1) The bending stiffness and strength of the sandwich beams increase with increasing the facing plates. The effect of stiffness of core on the bending stiffness of the beams is small. (2) The final fracture of the beams occurs due to compressive failure of the facing plates although the tensile strain of the facing plates at failure is greater than that of the compressive side facing plates. (3) The fatigue bending strength for the sandwich beams having thinner facing plates is high when the fatigue bending strength is given by the normalized strength using the static bending strength. (4) The fatigue failure of the beams occurs due to fracture of compressive side facing plates in compression at low cyclic fatigue while the tensile failure of tensile side facing plates leads the final failure of the beams at high cycle fatigue.