Load adaptivity of the mem-spring and its performance benefits in vehicle suspensions

It has been demonstrated in previous literature that a tapered dashpot is a physical embodiment of the mem-dashpot, while a displacement-dependent fluid inerter device can be modeled as a mem-inerter. In this paper, a displacement-dependent diamond-shaped structure spring device is found to be a physical realization of a mem-spring via both theoretical and experimental research. A quarter-car model of the suspension system equipped with the mem-spring is established by the Lagrangian method, and it is exhibited in simulation that the mem-spring has load adaptivity and the ability to improve suspension performance. An investigation reveals the mechanism behind load adaptivity from the perspective of energy storage, namely, a mem-spring with different initial displacement values can be equivalent to a semi-active spring performing an initial-position-dependent stiffness control strategy. Finally, the load adaptivity and performance benefits are verified through the bench test of the suspension system equipped with the mem-spring prototype. Thanks to such load adaptivity, the suspension system with the mem-spring can provide smoother and more constant ride comfort as well as better road holding performance than the one with a linear spring.