A shape memory alloy rotary-actuated reusable separation mechanism with high load-bearing capacity and low shock

As the number of spacecraft rises and payload weight increases, separation mechanisms need to have higher load-bearing capacity and generate minimal shock during the separation process to avoid affecting the system. This paper presents a shape memory alloy (SMA) rotary-actuated separation mechanism, featuring a resettable moving component design. The mechanism integrates an SMA wire rotary actuator for triggering, a thrust bearing structure to reduce friction, and a segmented nut structure for reliable load-bearing. When the SMA wire is electrically heated, it undergoes a phase transformation and generates an actuating force, causing the rotary shaft connected to it to rotate and output torque. After that, the thrust bearing structure connected to the rotary shaft rotates to release the outer ring of the segmented nut, thus releasing the bolt from the mechanism. In order to realize reusability, high load-bearing capacity and low shock, several designs have been proposed. First, a wrench interface is integrated into the rotary shaft for quick reset and reuse after separation. Second, through the ball anti-friction structure of the thrust bearing and the inclined load amplification structure between the segmented nut and the outer ring, the mechanism can realize a high load-bearing capacity. Besides, the SMA wires are arranged circumferentially around a cylindrical inner shell via pulleys and designed to be coupled with a bias spring, so that energy is gradually released during the separation process, minimizing the shock to the system. Based on the working principle and structural design, a prototype was fabricated and the performance tests were carried out. Test results demonstrate that the ultimate load of the mechanism is 45 kN, surpassing existing SMA actuated separation mechanisms of comparable size. Under a 45 kN load, the mechanism achieves separation within 60 ms at 10 A input current, with over 50 reuse cycles. It maintained functionality under simulated satellite random vibrations (10–2000 Hz, Grms is 14g) and sinusoidal vibrations (5–100 Hz, 10 g), confirming robust environmental adaptability. In the separation shock tests under a 45kN load, the maximum shock of the mechanism is 21.5 g, less than 1/100 of pyrotechnic mechanisms. The proposed SMA rotary-actuated reusable separation mechanism exhibits high load-bearing capacity and low separation shock characteristics, which can offer an effective solution for spacecraft connection and separation applications.