With the aim of improving micro-vibration isolation, a hybrid magnetorheological elastomer-fluid (MRE-F) mount with variable stiffness and damping is presented. The proposed mechanism combines a magnetorheological elastomer stiffness unit with a magnetorheological fluid damping unit in a parallel connection. On the basis of a structural design and magnetic circuit analysis, the performance of this prototype was investigated experimentally using an MTS machine under multi-operating conditions. The field-controlled capacities, including resultant stiffness, equivalent damping, as well as the amplitude and frequency dependence were validated based on the experimental data. This work demonstrates the feasibility of applying this hybrid MRE-F mount to isolation systems with a small displacement.

http://iopscience.iop.org/article/10.1088/0964-1726/25/1/015026/pdf

A hybrid magnetorheological elastomer-fluid (MRE-F) isolation mount: Development and experimental validation

Vibration isolation and noise control technologies are used in submarines on multiple systems and there are various reasons for employing these technologies. One of the principal reasons is to minimise the acoustic signature of the submarine so that it is difficult to detect. This paper contains descriptions of conventional and emerging noise and vibration isolation technologies that have and could be applied to submarines.

Recent developments in submarine vibration isolation and noise control

Tilting pad thrust bearings are a key component of marine propulsion shaft systems. The dynamic performance of thrust bearings has a significant influence on the propeller vibration. To investigate the axial oil film stiffness of tilting pad thrust bearings, a two-dimensional thermohydrodynamic model incorporating the vibration frequency is developed. The test apparatus and experimental identification model are also constructed. The axial oil film stiffness is experimentally identified at different speeds, loads, and temperature employing the hammer impulse excitation. The axial oil film stiffness between theoretical and experimental results is compared. The discrepancies are not more than 7% for 30 kN operation cases but increase with axial static load. This is partially because the influence of the pivot stiffness becomes obvious with the axial static load increase and cannot be ignored. The results indicate that axial oil film stiffness is at a magnitude of 109 N·m−1. Compared to foundation sti...

Theoretical and Experimental Study on the Axial Oil Film Stiffness of Tilting Pad Thrust Bearings

This study focuses on the element configuration of hybrid mounts which are combined with passive elements and active elements. The seven configurations are presented according to connection of an active element to a passive element. The dynamic characteristics and control performance of them are investigated qualitatively using Bode plots. With reference to the transmitted force from internal to external, three cases are selected. In addition, some numerical simulations for the three cases are carried out to confirm the performance quantitatively. Based on this research results, a novel hybrid mount with excellent performance will be able to be developed.

A Comparative Study on the Dynamic Characteristics and Control Performances of Hybrid Mounts According to Element Configuration

A new hybrid mount system is proposed for microvibration control in a high-tech factory. The mount consists of an airspring as a passive device and a piezostack actuator as an active device. The two devices are connected in series. Some numerical simulations and experimental tests are carried out to evaluate isolation performance of the mount system comprising of four proposed hybrid mounts. As a control logic, the specific algorithm is adopted for considering multiple target frequencies of excitation based on a Filtered-X LMS algorithm. The results are compared with isolation performance of the passive airspring mount system. It is confirmed that the proposed hybrid mount system has great performance on microvibration.

공기스프링과 압전작동기를 결합한 복합형 미진동 방진마운트 시스템 개발

In naval ships, some methods or devices are acquired both to cut off the transmission of vibration from shipboard machineries and to protect them from external shock loading. One of the approaches is to install the passive mountings between machinery and a flexible supporting structure. More advanced performance has become necessary recently so far as at high frequencies in order to retain the stealth function of certain types of naval vessels. For the purpose of this research, a novel hybrid mount for shipboard machinery installed on naval ships was developed. The mount is combined with a rubber mount and piezostack actuators. The rubber mount is one of the most popular and effective passive mounts to have been applied to various vibration systems to date. The piezostack actuator is featured by a fast response time, small displacement and low power consumption. Through a series of experimental tests conducted in accordance with MIL-M-17185A(SHIPS), MIL-M-17508F(SH), and MIL-S-901D which are US military specifications related to the performance requirements of the mount, it has been confirmed that the hybrid mount shows more effective performance for use in naval ships.

/pdf/a-study-on-the-hybrid-mount-against-vibration-and-shock-for-4qz9cybdbn.pdf

A Study on the Hybrid Mount against Vibration and Shock for Naval Ships

Most of the naval shipboard equipments strongly require isolati on devices to keep their performance and durability from severe noise and vibration loading. The rubber mount is well-known as one of most effective way to isolate major equipments from noise and vibration. The performance of the rubber mount is determined by characteristics of shock stiffness and vibration stiffness and the frequency range of in terest is up to several Kilo Hz in navy vessels. In this study, an vibration experiment method for the rubber mount has been developed as a foundation work for assessing dynamic stiff ness up to high frequency. Also experiments for a typical rubber mount has been carried out and the results has been discussed. ※Keywords: Rubber mount(고무마운트), Isolation(절연), Naval shipboard equipments(함정탑재장비), Dynamic stiffness(동적강성), High frequency(고주파) 1. 서론 함정에 탑재되는 장비는 선체의 진동 및 충격에 견디어야 하며 그 성능을 발휘해야할 뿐 아니라, 접수일: 2009년 3월 2일, 승인일: 2009년 3월 25일✝교신저자: hylee@cnu.ac.kr, 042-821-6626 발생되는 진동이 선체를 통하여 수중으로 방사되는 것을 감소시킴으로써 피탐성을 최소화하여야 한다. 탄성마운트는 이러한 진동 및 충격의 전달을 감소시키기 위한 목적으로 선체와 탑재 장비 사이에 설치하는 것으로서, 특히 방사소음을 줄이기 위해서는 일반적으로 고무마운트가 사용되고 있으며 그 성능(전달률)은 강성 특성에 의해 결정

Jeong-Seok Kwak

Papers

A Study on the Hybrid Mount against Vibration and Shock for Naval Ships

An Experimental Study on the Vibration of Rubber Mounts for Naval Shipboard Equipments