Design and analysis for a variable stiffness U-shape lamina emergent joint with integrated shape memory alloy (SMA-ULEJ)

Traditional flexible hinges provide compliant motion but lack real-time stiffness adaptability required for advanced applications. For adaptive stiffness applications, a variable stiffness lamina emergent joint with integrated memory alloy is proposed which can control the stiffness with higher precision, herein referred to as SMA-ULEJ. The equivalent spring system model consisting of shape memory alloy and slider of Lamina Emergent Joint is established, and the accuracy of the model is verified by finite element analysis. The principle and performance of the SMA-ULEJ are analyzed. The influence of the sliders in different positions on the variable stiffness performance of the joint is compared and analyzed. By driving the slider with shape memory alloy, the variable stiffness of the joint can be realized. The expansion of the SMA-ULEJ can realize more stiffness changes, which provides a potential solution for the design of variable stiffness robot links.