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Dynamic performance of a passive vehicle suspension can be improved with the help of an active actuator. However, there could be problematic actuation requirements, such as high energy consumption and large actuator forces. A novel design approach for passive-active-combined suspensions has been previously proposed by the authors to improve the trade-off between the dynamic performance and actuation requirements. To show its effectiveness in practical applications, an experimental study is carried out in this paper. First, a physical implementation of the active part of combined suspensions is proposed, which mainly includes a ball screw and a rotary brushless DC motor. Then, an experimentally verified network model of this physical implementation is developed by considering parasitic effects of the device. Taking a quarter car as an example, it is found that for the proposed setup, the inertia of the screw and motor rotor has an evident effect on suspension performance, while the friction of the ball screw, the mechanical loss and cogging torque of the motor are negligible. If the parameters of the passive part and the active controller gain are re-tuned after replacing the ideal active part with the identified network model of the proposed physical implementation, the optimal trade-off between ride comfort and actuation force can be retained or even improved. An example point on the updated trade-off has been verified via experiments, where the correlation coefficient on response matching is approximately 96%.

acuum-packed particle (VPP) systems have been recently used in the development of smart structures due to their ability to actively change material stiffness through the mechanism of granular jamming. By altering the strength of the vacuum pressure applied to the particles, the material can be proportionally and reversibly transitioned from a liquidlike low-stiffness state to a stiff state. The ability to control material stiffness in this way opens up different possibilities for the design of morphing and smart structures by allowing them to soften during deformation to reduce actuation energy requirements and to then stiffen once the desired shape has been achieved to provide a zero-energy holding mechanism. The following research describes two useful models that predict the mechanical response of VPP beams under flexural loading. Firstly, four-point bending tests with digital image correlation strain mapping are performed in order to measure the axial and transverse strains in a bending beam made from vacuum-packed particles. The test results show a nonlinear mechanical response, including a change in beam thickness with deformation, that motivated an analytical model of the structure incorporating a nonlinear material stress model based on the Mohr-Coulomb failure envelope. In addition, finite-element simulations are implemented using a Johnson-Cook model extension to predict the response under loading of three-dimensional beam elements at different vacuum pressure levels. Lastly, the models are compared to the experimental results, indicating good agreement. Both methods are shown to be useful for predicting the variation of stiffness of vacuum-packed particle beams.