Ride comfort enhancement for passenger vehicles using the structure-immittance approach

This paper investigates the ride comfort enhancement potential for passenger vehi- cles by employing inerter-spring-damping suspension struts. The inerter has been used on Formula 1 racing cars and several beneficial devices incorporating inerters have also been identified for ride comfort enhancement. However, previous investi- gations either were limited to simple network configurations with moderate perfor- mance improvement, or resulted in complicated configurations with a large number of elements which are impractical for real-life applications. In addition, some im- portant practical performance constraints have not been taken into consideration, such as high-frequency dynamic stiffness which influences the NVH performance, and frequency content consideration of the sprung mass acceleration which more directly relates to passenger perception. In this paper, a quarter-car model includ- ing top mount is studied, with the performance of a conventional suspension strut presented as baseline. The structure-immittance approach, which can cover all net- works with pre-determined numbers of each element type is adopted for identifying the optimal suspension configurations. Several configurations with up to a 13.3% performance improvement are identified with other practical performance indices to be no worse than the baseline. The suspension configurations proposed in pre- vious works are also considered for a sake of comparison, demonstrating significant advantages of the structure-immittance approach. Subsequently, a sensitivity anal- ysis against the sprung and unsprung mass changes is carried out, which represents cargo and tyre weight variations, respectively. Time domain response and other real- ity checks are then conducted for the out-performing configurations, which reconfirm the ride comfort enhancement and ensure no unexpected behaviour occurs.