Adhesively
bonded joints are being used increasingly in civil engineering, especially for
joints comprising
pultruded
glass-fiber reinforced polymer (GFRP)
laminates.
The layered material architecture, however, leads to a complex delamination
failure within the pultruded material, thus necessitating understanding of the
progressive failure
mechanism of such joints under axial tensile loading. In
this work, adhesively bonded joints composed of pultruded GFRP laminates,
including double and stepped lap joints, were experimentally investigated. The
static strengths of joints were obtained and the failure mechanism was
understood. Crack propagation and back face strain gages were successfully
employed to identify crack initiation and describe crack propagation, even
though the failure mechanism was always brittle. The dominant failure mode for
both types of joints was a fiber-tear-off failure that occurred in the mat
layers of the GFRP laminates. The critical strain energy release rate was
calculated and the resulting values from double lap and stepped lap joints
compared very well.