Stress and deformation of the sandwich box beam composed of face plates, sandwiched core and side beams under a three point bending moment are analyzed approximately by the use of the potential energy principle with consideration of orthotropic elasticity of the face plate and its additional deflection to that of the side beam. It is well known that the bending rigidity of a box beam decreases generally due to the shear-lag effect of the face plate. The decrease, however, presumably be somewhat prevented by a restraining action on the shear-lag effect in the face plate due to the shearing rigidity of the sandwiched core. The theoretical load vs. deflection curves and the strain distributions of the face plate agree well with the corresponding experimental results obtained for four types of test specimens with different dimensions and materials of the face plate.
Static tensile properties were examined on the sandwich type composite plates composed of steel-copper and iron-copper which were fabricated by means of diffusion bonding method. It was observed that the tensile strength of the composites agreed with the rule of mixture as a first approximation. The yield point of the copper clad iron was higher than the expected value which was obtained from an elementary theory combined with the rule of mixture. The fracture elongations of the copper clad iron and steel were increased comparing with those of the monolithic iron and steel due to multiple neckings which were observed on the parallel parts of the clad specimens.