This article examines the fracture behavior of sandwich type double cantilever beam (DCB) specimens under monotonic and cyclic loading conditions. The specimen consists of two layers of OFHC copper and one layer of ViaLux 81 photo-definable dry film. The ViaLux 81 is placed in between copper layers. Analytical expression for the strain energy release rate (GI) of the sandwich DCB specimen is derived by following the plate theory based model and compliance method. Finite element analysis has also been carried out on the specimen and the load displacement results for the specified crack or delamination length are obtained. The compliance equation in terms of the delamination length is derived for the specimens for obtaining the strain energy release rate (GI). From the generated R-curve of the interface, the failure load is estimated for the specified delamination length. From the crack growth data, the number of cycles to failure under cyclic loading is estimated for the initial delamination length.

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The simulation of damaged honeycomb sandwich structures is an important aspect in the structural health monitoring and prognosis. This paper studies finite element modeling aspects of delaminated honeycomb sandwich structure. The models proposed are 3-D model of the honeycomb sandwich construction using isotropic shell elements and a layered shell element model, both with contact elements defined in between the delaminated skin and core. Case study is conducted on damaged and undamaged metallic sandwich beam with 3-D shell element modeling and layered element modelling. The models are validated using three point bending test of damaged and undamaged beams. Results are compared with the experimental, theoretical and finite element results. The results show that the layered element modeling simulates the stiffness and gives the similar results to that of 3D model in the global responses and is computationally efficient. KEYWORDS: Honeycomb sandwich structure; Delamination; Finite element modelling; Three point bending test CITATION: K.R. Pradeep, S.M. Srinivasan, B.N. Rao and K. Balasubramaniam. 2012. Study on finite element modeling aspects of delaminated honeycomb sandwich beams, Int. J. Vehicle

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Composite structures are prone to delamination/de-bond and effective tool to simulate de-lamination is cohesive zone model. Cohesive zone model uses multiple adhesive failure parameters. The influence of adhesive parameters on the delamination and fracture of Double cantilever Beam, subjected to Mode-I loading through finite element simulations is studied usingExponential Cohesive Zone Model (ECZM). Influence of Normal stress (σ), normal deflection (δn) and tangential deflection (δt) on the de-bond propagation is examined.From the analysis it is found that the tangential deflection (δt) has negligible impact on Mode-I loading and fracture of the specimen. Significant effects are seen for the perturbation of Normal stress (σ) and Normal deflection (δn). A Finite element based ECZM for composite layer (HTS/M18) with EPG 2601 adhesive is proposed. The model is validated by comparing with test data.