Interface Fracture Assessment on Sandwich DCB Specimens

Abstract

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.

Studies on effect of pre-crack length variation on Inter-laminar fracture toughness of a Glass Epoxy laminated composite

“…From the table 1, percentage of error between both the theories will be less than 3%. Also, the inter-laminar fracture toughness depends on the pre-crack crack length of the DCB specimen [17]. Fig.4 shows the load vs. displacement for ENF specimens which were tested with different length of pre-cracks.…”

“…DCB and ENF of 6 set of specimens are used with varying pre-crack lengths for mode-I and Mode II fracture tests. Similarly, the inter-laminar fracture studies were conducted using analytical and numerical techniques by earlier researchers [17,18]. The peak loads at failure for the DCB were estimated from the experimental results and used to estimate the Mode I critical energy release rate.…”

Analytical solution of some delamination scenarios in thick structural sandwich plates

“…Equations (27) to (29) define the invariant form of the equilibrium equations, because independently of the applied theory, these equations have the same form. It is apparent that the differences among the equilibrium equations of FSDT, SSDT and TSDT are the K ij displacement multiplicator matrix elements and the w ð pÞ vector of primary parameters.…”

“…The function of the external load in this case is Q n ¼ 4Q 0 =ðnÞ [117]. By taking back the solution in equation (32) into the strain field (equations (18) and (19)), then by expressing the stress resultants in accordance with equations (21) and (22), we can utilize the equilibrium equations given by equations (27) to (30) to reduce the system of Partial Differential Equations (PDEs) to a system of Ordinary Differential Equations (ODEs), which can be solved by the state-space approach [122]:…”

“…Furthermore, we define the equivalent higher-order stress resultants based on the vector of primary parameters (equations (9) to (11), (15) and (16)) and the equilibrium equations (equations (27), (28) and (30)) as:…”