Design and Test of Compliant Bending Joints Driven by Two-way SMA Wire

A compliant bending joint, which is composed of aluminum alloy ring, hyper elastic shape memory alloy (SMA) and two-way shape memory alloy wire, is designed and demonstrated. Among which hyper elastic SMA is arranged as the supporting rod and the two-way SMA wire is used as the driving mechanism. The compliant joint can be bent by the two-way SMA wires driven by direct current and it can return to its original state as the current is unloaded. When the DC current is set as 2.1A, the shrinkage rate of the two-way SMA wire is 4.02%. The dynamical model of the bending joint is established in order to obtain bending angles of the two joints under different loading conditions. Bending tests on the compliant Joints are demonstrated and the results show the maximum bending angles of the two joints are 43.1° and 22° respectively, which is in good agreement with the theoretical analysis result.