Static behaviours of carbon fibre composite strip with bifurcated type shape memory alloy pins

A numerical study of the static behaviours of composite strip with bifurcated type shape memory alloy pins has been conducted. The case of bifurcated type shape memory alloy pins inserted inside the composite strip around the hole to reinforce the laminate, which was subjected to the axial stress was simulated. The models for stress analysis were established by using ANSYS finite element programme. Two types of shape memory alloy pins were proposed to insert along the through thickness direction of the carbon fibre woven fabric composite strip to induce the clamping force. The pre-tensioned load was applied to the shape memory alloy pins in order to reduce occurrence of delamination in the laminate. Three-dimensional elements and contact elements were used to simulate the contact between the composite laminate and shape memory alloy pin to investigate the stress distribution around the hole in the composite strip. The effect of pre-strain of shape memory alloy on the stresses inside composite was studied. The results show that the stress characteristics of the button-shaped and bifurcated shape memory alloy pin models are similar; however, the stresses for the button-shaped pin model are lower. The tensile and compressive stresses, both in button-shaped and bifurcated pin models, are strongly dependent on the percentage of pre-strain of the shape memory alloy. It is therefore concluded that the shape memory alloy pin method was significantly reduced the stress concentration of the composite strip laminate.