Seating system vibration control of commercial vehicles

Vibrations can cause discomfort and harm to both vehicle operators and passengers. Therefore, a well-designed seat suspension isolation system is crucial to improve comfort and reduce damage to human health. This research aims to develop a design method for seat suspension systems and seat cushions to improve the vibration isolation performance of commercial vehicles. The novelty of this research thesis is to improve vibration isolation by inventing a novel seat suspension structure of the quasi-zero stiffness and seat cushion of negative Poisson’s ratio cells. The main contribution of this research thesis is the design and optimisation method for a seat suspension structure of quasi-zero stiffness and seat cushion of negative Poisson ratio cells for enhanced vibration isolation performance. Analytical and multiple body dynamics simulation models through the Matlab and ADAMS software have been established to predict the transmissibility ratio of the quasi-zero stiffness seat suspension structure and validate each other. The seat suspension structure of the quasi-zero stiffness has been optimised to minimise its peak transmissibility ratio. Analytical and ANSYS finite element simulation models of the auxetic star and honeycomb cells of the negative Poisson ratio have been developed to calculate Young’s modulus and Poisson’s ratio and to validate each other. The 3D printed negative Poisson’s ratio cell structure has been tested in the Instron machines to measure Young’s modulus, damping loss factor, and Poisson’s ratio and to validate the analytical and ANSYS finite element simulation models. The auxetic star and honeycomb cells of the negative Poisson’s ratio have been optimised to minimise its Poisson’s ratio. A novel seat cushion of the negative Poisson’s ratio cells has been designed and simulated where the stiffness of the seat cushion is calculated from Young’s modulus of the negative Poisson’s ratio cells from the analytical model. The damping coefficient of the seat cushion is calculated from the measured damping loss factor of the 3D-printed star and honeycomb cells. The auxetic (honeycomb structure) cell dimensions of the seat cushion are optimised in a seat suspension model of a full vehicle suspension to minimise the peak transmissibility ratio from the floor to the passenger’s head.