Experimental Study of the Impact of Interlayer Elastomeric Foam on Failure Pattern of Composite Laminated Panels with Various Layups

Enhancing the failure behavior of laminated composite panels for various industrial, aeronautical and naval applications has been concerned by researchers and engineers. In the present paper, in order to create a fuselage time between the initial failure on the top composite panel and final failure due to failure of the bottom panel, an interlayer elastomeric foam was employed using epoxy adhesive and the failure pattern was compared between the single and sandwich composite panels for various layup methods of the laminates.  The examined layup methods are composed of a stronger direction, cross-ply and woven plies laminates, in which the enhancing influence of an elastomeric foam from PE-EVA blend (28% EVA) was observed in terms of maximum load carrying and energy absorption capacities. The objective for application of an elastomeric foam was omission of disadvantage by inflexible crushable foams. Although, the elastomeric foam supplied aa lower flexural modulus for the sandwich composite panels due to its lower shear rigidity, it could distribute stress concentration areas from the top to the bottom composite panels, to create a considerable fuselage to reach the ultimate strength via absorption of considerable energy. The results showed promising performance for failure response of elastomeric foam cored sandwich panels. Application of the interlayer elastomeric foam in the case of composite panels with lower stiffness showed larger enhancing effect.The objective for application of an elastomeric foam was omission of disadvantage by inflexible crushable foams. Although, the elastomeric foam supplied aa lower flexural modulus for the sandwich composite panels due to its lower shear rigidity, it could distribute stress concentration areas from the top to the bottom composite panels, to create a considerable fuselage to reach the ultimate strength via absorption of considerable energy. The results showed promising performance for failure response of elastomeric foam cored sandwich panels. Application of the interlayer elastomeric foam in the case of composite panels with lower stiffness showed larger enhancing effect.