Experimental study on mechanical properties and recoverability of FRP/shape memory alloy composites

Using the recovery effect of shape memory alloy (SMA) to introduce prestress into fiber reinforced polymer (FRP) is a new idea. In this paper, FRP and SMA are compounded to form a new composite material for structural strengthening and repair. The mechanical properties and limited recovery properties of FRP/SMA composites are tested. In the mechanical property test, the number and diameter of SMA wires are taken as test variables, and their effects on the tensile properties of FRP/SMA composites are analyzed. In the limited recovery test, the SMA wire diameter and pre-strain level were taken as test variables to analyze their effects on the recoverable properties of SMA wire and FRP/SMA composites. On the basis of experimental research, the regression equations of recovery stress temperature of SMA wire and FRP/SMA composites are given. The test results show that increasing the number of SMA wires can improve the maximum fracture strain and tensile strength of the composite. The more wires are added, the greater the residual strength after fracture. The diameter of SMA wire significantly affects the tensile elastic modulus of composite specimens. In the limited recovery performance test, the recovery stress of FRP/SMA composites shows an obvious upward trend with the increase of temperature in the phase transition range, and the maximum recovery stress of composites will increase with the increase of pre-strain level. The modified model based on Brinson’s model is proposed, and the predicted values are in good agreement with the experimental values, which can effectively predict the relationship between the recovery stress and temperature of SMA wire and FRP/SMA composites.