A new two-terminal mechanical element named the mem-inerter described by a relation between integrated momentum and displacement is introduced as the memory counterpart of an inerter. It exhibits an individual “fingermark” featured by a pinched hysteresis loop located within the momentum-velocity plane. The mem-inerter is attached to a simple mass-spring-damper system. The system equipped with a mem-inerter is mathematically modeled, and its nonlinear vibration equation is derived. To ensure a fair performance comparison between the systems equipped with the mem-inerter and the inerter, the nonlinear mem-inerter with an appropriate helix pitch can be proved to be equivalent to the linear inerter with a fixed inertance by the fact that the systems have the same displacement transmissibility for forced response. Under such a premise, it is found that the system with the mem-inerter having positive initial displacement has better performance for free response than the system with the inerter. Furthermore, the application scenario that both systems are arranged on an inclined plane is taken as an example of the positive initial displacement. The example demonstrates that the system with the mem-inerter has significantly better transient performance than the system with the inerter.

Aim to balance the ride comfort and handling stability of vehicles and improve suspension performance, this paper presents a novel lateral interconnected hydro-pneumatic “inerter-spring-damper” (ISD) suspension integrating a hydro-pneumatic suspension and a fluid inerter, which realizes the lateral connection of the suspension through the inerter. The equivalent mathematical model of the lateral interconnected ISD suspension is established; the 15-degree-of-freedom (DOF) model of the vehicle is built in AMESim, and the key parameters are optimized by genetic algorithm. The response characteristics of the novel hydro-pneumatic ISD suspension and traditional hydro-pneumatic suspension under pulse and random input are comparatively analyzed. The lateral interconnected hydro-pneumatic ISD suspension prototype is developed and tested on the bench. The simulation and test results prove that the proposed new suspension structure has a more effective shock absorption performance than the traditional hydro-pneumatic suspension. Overall, the novel hydro-pneumatic ISD suspension better consider to the ride comfort and handling stability, and the structure is simple, compact, and easy to deploy on practical vehicles.

This paper presents a modified skyhook‐inertance control strategy which is realized through a hydraulic device of continuously adjustable inertance between sprung mass and unsprung mass. The parasitic damping inherent in the hydraulic device as well as the inertance is taken into account in the modified control strategy. Differential equation models are built to compare the performance of the semiactive suspension employing the modified control strategy with that of the passive suspension. The results demonstrate that the semiactive suspension significantly reduces sprung mass natural frequency, attenuates the resonant peak value without the penalty of deterioration at higher frequencies, and achieves over 28% improvement on ride comfort, compared with the passive suspension in unload condition. The proposed hydraulic device, together with its control strategy, can be used to reduce the variation of sprung mass natural frequency and ride comfort between unload and full‐load condition.

Aiming to improve the road friendliness so as to reduce the road damage caused by heavy multi-axle vehicles, and to enhance the ride comfort, we propose a kind of hydro-pneumatic ISD suspension structure, which is equivalent to a two-stage ISD structure integrating a traditional hydro-pneumatic suspension and a fluid inerter. Firstly, based on the 1/4 model, a genetic algorithm is used to optimize the key structural parameters of hydro-pneumatic ISD suspension. Secondly, the AMESim dynamic model of heavy multi-axle vehicles is built for the performance comparison between the traditional hydraulic and hydro-pneumatic ISD suspensions. Finally, this paper machines a hydro-pneumatic ISD suspension to replace the traditional hydraulic one in a heavy multi-axle vehicle to carry out a road test. Test results indicate that the proposed suspension can effectively restrain the vibrations of sprung and unsprung mass and improve ride comfort as well as road friendliness. The hydro-pneumatic ISD suspension can be applied to engineering.