In this paper, a novel structure of a controlled multi-channel semi-active magnetorheological (MR) fluid mount is proposed, including four controlled channels and one rate-dip channel. Firstly, the magnetic circuit analysis, rate-dip channel optimization design, and MR fluid mount damping analysis are given. Secondly, the mathematical model of the controlled multi-channel semi-active MR fluid mount is constructed. We analyze the effect of controlled multi-channel closing on the dynamic characteristics of the mounts and the effect of the presence or absence of the rate-dip channel on the low-frequency isolation of the mount. Finally, the controlled multi-channel semi-active MR fluid mount was applied to the $\mathrm{1}/\mathrm{4}$ vehicle model (a model consisting of an engine, a single engine mount, a single suspension and a vehicle frame), with the transmissibility of the engine relative to the vehicle frame at low frequency and the transmissibility of the engine reciprocating unbalanced force to the vehicle frame magnitude at high frequency as the evaluation index. Numerical simulation shows the following points. (1) The controllable multi-channel semi-active MR fluid mount can achieve adjustable dynamic stiffness and damping with applied 2 A current to different channels. (2) With known external excitation source, applied currents to different controllable channels can achieve the minimum transmissibility and meet the mount wide-frequency vibration isolation requirement, while adding a rate-dip channel can improve the low-frequency vibration isolation performance of the MR fluid mount. (3) Switching and closing different controllable channels in the $\mathrm{1}/\mathrm{4}$ vehicle model can achieve the minimum transmissibility of low-frequency engine vibrations relative to the vehicle frame and high-frequency engine vibrations reciprocating an unbalanced force to the vehicle frame. Therefore, the design of the controllable multi-channel semi-active MR fluid mount can meet the wide-frequency isolation.

This paper introduces a novel type of magnetorheological fluid (MRF) mount designed to achieve wide-frequency vibration isolation for engines. While previous studies have explored vibration isolation using hydraulic mounts, there has been limited research on achieving wideband isolation with MRF mounts. Consequently, this paper presents an innovative MRF mount structure and investigates wideband vibration isolation control for engines. Initially, experiments with a multi-channel MRF damper validate the switchable operation of controllable channels. A novel controllable multi-inertia channel MRF mount system is proposed, aligning the working mode of controllable inertia channels with that of the MRF damper. The lumped parameter method is employed to derive the mathematical model of the MRF mount, and its high and low-frequency dynamic characteristics are thoroughly examined. Subsequently, a real-time multi-island genetic algorithm-optimized controller is developed to investigate wideband vibration isolation within the MRF mount system. The findings indicate that: (1) The MRF mount demonstrates adjustable low-frequency dynamic stiffness and loss angle within the frequency range of f = 0–50 Hz. In the frequency range of f = 50–100 Hz, the mount achieves its lowest dynamic stiffness value, effectively addressing the issue of high-frequency stiffening. (2) The real-time multi-island genetic optimized controller exhibits superior vibration isolation performance compared to traditional sky-hook control and hybrid sky-hook control methods, achieving optimal vibration isolation for the mount.

This article introduced a piezostack-driven jetting dispenser for a microelectronic packaging process. The dispenser had a compact displacement amplification module using two piezostack actuators for achieving compact design and maintaining high jetting performance and improving internal stress on the piezostack actuators. In this article, a working principle of a jetting dispenser configuration was introduced and was followed by the presentation of a displacement amplification mechanism using a cylindrical pivot. The dimensions of the amplification mechanism were determined based on a theoretical calculation of the system and the finite element analysis results. The internal stress of the piezostack and the output displacement of the dispenser were investigated at different operational frequencies. The experimental system with the jetting dispenser was manufactured, and the system performance was verified experimentally. For evaluating the performance, a mixed glycerol/ethanol was used for the dispensing fluid. The jetting system in this study achieved an ideal jetting performance at a jetting frequency of 350 Hz and a droplet diameter of 0.42 mm.

This research intends to further improve the understanding of vibration damage mechanisms in the wrist area and to establish a more effective biodynamic model of the hand-arm system. Scholars have conducted some research work around the influencing factors of vibration response and commonly used vibration transmissibility to characterize the local vibration transmission characteristics of the hand-arm system. In this paper, a hand-transmitted vibration test platform was built according to ISO 10819, and a random combination of four ergonomic factors, namely wrist posture, arm posture, grip force, and thrust force, was used to test the vibration response of six subjects’ wrists; the total vibration transmissibility of the wrist was calculated according to the transmissibility formula. The effect of the four factors on the total vibration transmissibility of the wrist part was comprehensively analyzed, in which the wrist posture was proposed for the first time. The results show that (1) vibration transmissibility of the wrist is not only related to the arm posture, thrust force, and grip force but also related to the wrist posture; (2) the total vibration transmissibility and resonance frequency on the wrist has small correlation with large grip force and thrust force, and the vibration transmissibility of grip force 30 N and 60 N are basically equal in the low-frequency band (from 5–10 Hz to 5–20 Hz); (3) the wrist postures have a significant effect on the total vibration transmissibility at the wrist.

This study introduces a novel hydraulic mount designed to achieve broad-spectrum engine vibration isolation. While previous studies have focused on vibration isolation using hydraulic mounts, there is a scarcity of research on achieving wideband vibration isolation with such mounts. To address this gap, this article proposes a new bell plate hydraulic mount structure that includes an inertia channel, a decoupler membrane, and two bell plates. First, the study analyzes the impact of structural parameters on the dynamic characteristics of the new bell plate hydraulic mount across high and low frequencies. Second, it compares how varying the number of bell plates affects the hydraulic mount’s dynamic behavior across different frequency ranges. The findings reveal the following key points: (1) The number of bell plates has minimal influence on the low-frequency dynamic characteristics of the hydraulic mount. (2) Increasing the number of high-frequency bell plates from n = 0 to n = 2 reduces the peak dynamic stiffness of the hydraulic mount by 69.88% and decreases the hysteresis angle by 37.71%. (3) At higher frequencies, the dynamic characteristics of the hydraulic mount are notably influenced by parameters such as the equivalent cross-sectional area A _m2 of the second bell plate, the surrounding equivalent cross-sectional area of the hole A _t2, and the fluid inertia coefficient I _t2 associated with bell plate 2.