Finite Element Analysis of a Smart Hinge Based on Shape Memory Polymer

To study the shape memory behavior of a novel hinge based on shape memory polymers and the reinforcing effect of metal materials on the shape memory polymer (SMP) hinge, a user-defined material mechanical behavior (UMAT) subroutine available for ABAQUS was written and a finite element method for SMP complex structures was developed based on a three dimensional SMP stress-strain-temperature relationship. Using the method, folded and unfolded shape memory behaviors of the SMP hinge, including loading under high temperatures, cooling, unloading under low temperatures and heating, were simulated. The folding processes of the reinforced SMP composite hinge were simulated and discussed. Results show that the SMP hinge after forward and reverse folding can be automatically expanded by controling the temperature, therefore, it can effectively solve the problem of driving complex and overshoot vibration in the traditional hinge. Critical bending moment and steady bending moment of the metal-reinforced SMP composite hinge are significantly improved, in which the reinforcing effects decrease in order of alloy steel, cast steel, gray iron and duralumin.