Mixed-mode behaviour of composite adhesive joints

This book presents an experimental and numerical analysis of a composite Single-Leg Bending (SLB) bonded joint with three adhesives. A J-integral formulation was considered to obtain the energy release rate for mode I and II, tensile (JI) and shear (JII), respectively, whereas the cohesive laws are attained by differentiation of the JI-w0 and JII-0 curves, where w0 and 0 are the local normal separation and local tangential slip at the crack tip, respectively. Afterwards, the fracture analysis was performed, where the experimental results were compared through load-displacement (P-) curves. The JI and JII values were analysed by R curves and fracture envelopes. These latter were used to establish which criterion was more suitable for each adhesive type. For last, the tensile and shear stresses were determined through the cohesive laws, attained by the direct method. Overall, a good agreement on the fracture properties was obtained between specimens of the same adhesive. Moreover, the cohesive laws also presented a good correspondence between specimens, and will enable the design of adhesively-bonded joints with arbitrary geometry.