Study On Theory Of Structural Crack Self-repairing Based On Shape Memory Alloy

Shape memory alloy (SMA for short) has characteristics of various forms of deformation, shape memory, super elasticity, large deformation, generating a driving force when recovery being restricted, strong resistance to fatigue, easily combining with concrete, steel and other structural material, elastic modulus will change according to the phase transition state.Shape memory alloy intelligent concrete, is the use of shape memory alloy of shape memory, super elasticity and the characteristics of the restoring force generated by the great restrictions when replying, control and restore the deformation and deflection of structure, so as to realize the self repairing concrete crack. The basic principle is: embedd shape memory alloy wire at spots on parts or components of the concrete structure where cracks are easy to produce. Concrete and its components deformate under the action of external force, the shape memory alloy wire will be deformed. When the external force disappears, the shape memory alloy wire will produce elastic recovery effect, shape memory alloy wire restricted applied compressive stress on the cracks, inhibiting the development of cracks and foring them to become small or closed, so as to realize the self repair of cracks. Based on the SMA structural self repairing superior characteristics we need to research it. In this paper, based on real experiments of concrete beam crack repairing and simulated model built with finite element software ANSYS for comparison, influence factors of shape memory alloy wire for concrete beam crack repair in the conditions of combinating concrete with shape memory alloy wire and its change is researched.Based on the bending beam structure for external installation and embedded shape memory alloy reinforced by simulation with experiment and finite element software ANSYS,the calculation model is establish, the bearing capacity and the recovery of cracks of beam structure with or without shape memory alloys has been investigated. The results show that:the external installation and embedded shape memory alloy can effectively reduce the deformation of beam under loading, let the structure get the ability of self repair, improving the carrying capacity of the structure and the mechanical performance of the structure, also can increase the structural integrity and rigidity. Based on simulation of the bending beam structure embedded with shape memory alloy with experiment and calculation model established by finite element software ANSYS, the recovery of the concrete structure installed different form of shape memory alloys has been investigated. The results showed that:(1) capacity of the super elastic SMA concrete beam is good, both the unloading residual deflection and residual crack is smaller than ordinary concrete beam.(2) the bonding force can improve the bearing capacity of beam, but decrease the self repair capacity of beam.(3) not only can bond force improve the bearing capacity of prestressed beam but also can improve the beam energy dissipation capacity.Results of this paper can be used for reference in the design and calculation of crack repairing of similar concrete beam.