Summary
A semi‐active inerter‐based vibration isolator with semi‐active inerter is presented in this paper; the inertance of the semi‐active inerter is hierarchically adjusted between two values: the maximum inertance and minimum inertance. On the basis of the mechanical property of the semi‐active inerter, two acceleration–velocity‐based control strategies are proposed, which are the relative‐acceleration–relative‐velocity (RARV) control strategy and the relative‐acceleration–absolute‐velocity (RAAV) control strategy. The dynamic responses of the semi‐active inerter‐based vibration isolator with the two control strategies are obtained using the averaging method and further checked by the numerical results. Four performance indices are defined to evaluate the isolation performance of the semi‐active inerter‐based vibration isolator: maximum dynamic displacement, maximum transmissibility, isolation frequency band, and transmissibility in the higher isolation frequency band. The solving process to determine the four performance indices is investigated in detail in the paper. The results show that for the semi‐active inerter‐based vibration isolator, the maximum dynamic displacement and transmissibility are smaller than the passive one; the latter two performance indices fall in between the value when the maximum inertance and minimum inertance are achieved for the passive one. In addition, the isolation performance of the semi‐active inerter‐based vibration isolator with the two control strategies are compared based on the four performance indices.
Inerter, which is defined as a two-terminal mechanical element, has the characteristic that the force generated at its two terminals is proportional to the relative acceleration between its two ends. Here, the inerter is used in the vibration isolation system; eight kinds of one-stage inerter-based vibration isolators are presented in this paper. Dynamic equations of eight kinds of one-stage inerter-based vibration isolators are established, the natural frequency is considered, and the dynamic response and transmissibility are obtained using the time domain analysis method or the Laplace-transformed method. Four performance indexes are defined to evaluate their isolation performance and compared with the linear vibration isolator (LVI). The best structural parameters of these one-stage inerter-based vibration isolators are determined using the H[Formula: see text] optimization method based on the fixed-point theory, which aims to minimize the maximum transmissibility. The results show that compared with the LVI, some kinds of one-stage inerter-based vibration isolators can offer a better isolation performance according to the four performance indexes. Furthermore, the best vibration isolator among these vibration isolators is determined by the four performance indexes.
The noise source of hybrid electric vehicle is varied, which makes the frequency band from low-frequency to highfrequency distribution. Using a single material to control the hybrid electric vehicle interior noise to improve the performance of vehicle, noise, vibration, and harshness performance is limited. In this article, the composite noise reduction materials which have the function of damping and acoustic absorption are used to control the vehicle interior noise. First, the noise characteristics of the hybrid electric vehicle are analyzed. The distribution of the hybrid electric vehicle interior noise is obtained. Then, the sound-absorbing properties of polyester-polypropylene bi-component fiber are analyzed. The low-frequency noise reduction principle of butyl rubber damping material is also analyzed. Finally, the noise reduction materials consisting of polyester-polypropylene and butyl rubber are added to the hybrid electric vehicle roof and floor. After improving material, the hybrid electric vehicle interior noise is test. As the result, the car driver's right ear A-weighting sound pressure levels have been greatly improved. The low-frequency noise below 400 Hz reduced 1.5 dB(A), and the high-frequency noise above 400 Hz reduced 5.2 dB(A). The total noise reduction reached 3.3 dB(A) near the driver's right ear, which significantly improve the noise, vibration, and harshness performance of hybrid electric vehicle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.