The purpose of the study was to develop a mathematical model of a flat composite spring operating in the region of small displacements and having a shape memory effect. To describe the behavior of the material, we applied a phenomenological approach based on the phase transition diagram; as the material model, we chose the Brinson phenomenological model. As a result, we proposed relationships for determining the reduced mechanical characteristics of a monolayer equivalent to a composite layer in the spring. The memory effect was taken into account by an additional internal force factor, i. e. the shape memory moment during bending, which resulted from the cross-section orientation of the martensite. To obtain the elastic characteristic of the spring, we used a finite element approach, in which the shape memory moment acts as an additional nodal load. Eventually, we introduced an algorithm for the dependence between the bending moment in the section and the shape memory moment for isothermal loading in the martensite stability zone and obtained the dependences of the shape memory moment during bending on the bending moment for various configurations of the cross-section of the spring.

The article considers possibility of creating a safety element for a safe electrical outlet based on the shape memory effect. Numerical model of helical cylindrical spring of the shape memory alloy is developed. The phenomenological approach based on the phase transition diagram is used to describe material behavior. Shape memory effect is included using additional internal force factor i.e. the shape memory moment under torsion. An algorithm for constructing the relationship between the torque in cross section and the shape memory moment for isothermal loading is presented. The problem of simultaneous deformation of shape memory alloy spring and flat copper spring under heating is solved. The contact plate is replaced by an equivalent spring. Spring stiffness is obtained using a system of nonlinear differential equations describing the bending of a bar.