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Helmholtz resonator is a very common anechoic measure, and it is widely used in pipe acoustic fields. Based on the enlightenment of the classic Helmholtz resonator, this paper proposes a headrest resonator model and extends it to the acoustic field of the passenger cabin to improve the road noise in the car. Firstly, through the theoretical model of Helmholtz resonator, the relationship between its resonance frequency and the geometric size of the resonator is clarified. Secondly, the influence of the headrest resonator on the acoustic field characteristics of the car is studied through finite element simulation analysis. It is demonstrated that the headrest resonator is placed in the car, and the sound pressure distribution characteristics of the passenger's inner ear near the resonance frequency change significantly. At the same time, through 3D printing, a sample of the headrest resonator is made.

The seat-occupant coupling system (SoCS) is nonlinear, and its vibration characteristics directly affect the dynamic comfort of the human body. To simulate the vibration characteristics of the SoCS accurately and provide a reference for the dynamic comfort, the finite element human body model and SoCS model are established in this paper. First, tests for the static stiffness of the polyurethane foam and the dynamic apparent mass (APMS) of a human body are performed to expose the nonlinearity of the seat and the human body, respectively. Then, vibration transmissibility test is carried out to evaluate the vibration characteristics of the SoCS. Third, the simulation models (including the human body model and the SoCS model) are founded and calibrated based on the above test data. Finally, the consistency of simulation and experimental results is evaluated and quantified by introducing the goodness of fit.

The open-cell polyurethane foam has a significant influence on the dynamic response of the Seat-occupant Coupling System (SoCS). Hardness, as an important property of foam, significantly impacts the compliance of human body support. Therefore, it is necessary to study the effects of varying foam hardness on the vibration transmitted to the human body. In this study, the effects are investigated by combining the test and simulation. In the test, the vibration transmission characteristic is measured and analyzed using Transmissibility, Seat Effective Amplitude Transmissibility (SEAT) value, and Weighted Root-Mean-Square value (W-RMS). In addition, the properties o dynamic stiffness and damping are also discussed. In the simulation, combined with the test results of dynamic stiffness/damping, a three-degree-of-freedom (3-DOF) model of SoCS is established. Meanwhile, by introducing goodness of fit, the consistency of simulation and test results is evaluated and quantified.

The characteristics of a notchback passenger vehicle wakes have been investigated. The experiment was mainly focused on the effect of rounding trunk-deck end on the steady and unsteady characteristics of the flow structure in the wake of the vehicle. The results showed that the formation of the trailing vortices were enhanced and the turbulence intensity in the wake was increased by rounding the trunk-deck end, although the frequency of the dominant fluid motion changed little. Simultaneous measurement of the velocity in the wake showed the dominant fluid motion over the rear of the vehicle and in its wake is highly correlated with the flow that comes through its underbody.