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Aiming at the problems of chemical pollution and the inability to reuse the initiation method adopted by the traditional hood pop-up mechanism, a new hood pop-up mechanism that uses shape memory alloy (SMA) as the trigger power element is proposed to realize the improvement of the hood pop-up mechanism. High-speed triggering and reversible recovery, the mechanism is simple in structure, quick in response, and can be manually recovered after being bounced, which can be adapted to various car models. After the sensor is triggered, the supercapacitor heated the SMA element to drive it at a high speed. The locking mechanism is activated to release the energy stored in the spring, and the engine hood is lifted and limited after reaching a certain height. After the design of the engine hood lifting mechanism and the determination of parameters, the spring stiffness that meets the pedestrian protection requirements is determined to be 11000N/m by the numerical simulation method. Dynamics modeling and simulation were carried out to study the influence of different parameters on the bouncing response. Experimental results show that when the spring stiffness increases from 2000N/m to 5000N/m, the release time decreases from 19ms to 12ms, and the time needed to spring up to 100mm height decreases from 136mm to 84mm. The response speed of the spring mechanism is accelerated, which is consistent with the simulation results.
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