Tapered-double cantilever-beam joints were manufactured from aluminium-alloy substrates bonded together using a single-part, rubber-toughened, epoxy adhesive. The mode I fracture behaviour of the joints was investigated as a function of loading rate by conducting a series of tests at crosshead speeds ranging from 3.33 x10 -6 m/s to 13.5 m/s. Unstable, (i.e. stick-slip crack) growth behaviour was observed at test rates between 0.1 m/s and 6 m/s, whilst stable crack growth occurred at both lower and higher rates of loading. The adhesive fracture energy, G Ic , was estimated analytically, and the experiments were simulated numerically employing an implicit finite-volume method together with a cohesive-zone model. Good agreement was achieved between the numerical predictions, analytical results and the experimental observations over the entire range of loading rates investigated. The numerical simulations were able very readily to predict the stable crack growth which was observed, at both the slowest and highest rates of loading. However, the unstable crack propagation that was observed could only be predicted accurately when a particular rate-dependent cohesive zone model was used. This crack-velocity dependency of G Ic was also supported by the predictions of an adiabatic thermal-heating model (ATM).

The present research shows a fractographic analysis, using a scanning electron microscope (SEM), based in previous experimental tests of the delamination under mode I fatigue loading for two aeronautical quality composite materials at different test temperatures (90, 20 and −60 °C) in order to analyze the matrix and temperature influence (flight conditions). The materials employed are composed of two different epoxy matrixes and the same unidirectional carbon fiber reinforcement. This study suggests a variable behavior depending on the temperature and the type of matrix used.

In the present research the fracture behavior in mode I under static loading of two aircraft quality composites materials has been analyzed at different test temperatures. The composites under study are made of the same unidirectional AS4 carbon fiber reinforcement and had different matrix of epoxy resin, one made of epoxy type 3501-6, and the other with epoxy type 8552 (modified to increase its toughness). Double cantilever beam (DCB) specimens were tested for different temperatures: 20 °C (room temperature), 0 °C, −30 °C and −60 °C, in order to simulate flight conditions. The results obtained from the static tests were analyzed using the Gompertz function.

This work aims to study the behaviour against delamination under static modes I and II of adhesive bonded joints in unidirectional carbon-fibre/epoxy prepreg. The double cantilever beam and end notched flexure tests were used to characterize the influence on the interlaminar fracture toughness under pure mode I and pure mode II, respectively. Three structural adhesives from different manufacturers were tested in comparison with the original material, that is, without adhesive bonded. The fracture surfaces were also examined for each joint system.

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