摘要：
This system uses air springs and rubber layer as passive vibration isolation elements and giant magnetostrictive actuators as active vibration isolation elements. Actuators and air springs are arranged in parallel. The air springs and the rubber layer of the passive system are synthesized so as to minimize the root-mean-square values of amplitude of the micro-manufacturing platform and the discrete time LQG controller based on a state space model is employed for controlling actuators. Simulation studies show that the developed active vibration control system has good isolation performance against the floor disturbance over wide frequency area. For random or white noise excitation, the amplitude of micro-manufacturing platform is reduced to approximately 15% by the active control system.
期刊：
International Journal of Mechanical Sciences,2002年44(12):2415-2425 ISSN：0020-7403
通讯作者：
Rao, KP
作者机构：
City Univ Hong Kong, Dept Mfg Engn & Engn Management, Kowloon, Hong Kong, Peoples R China.;Cent S Univ, Dept Mat Sci & Engn, Changsha 410083, Peoples R China.;Nehua Univ, Coll Mech Engn, Hengyang 421001, Peoples R China.;[Rao, KP] City Univ Hong Kong, Dept Mfg Engn & Engn Management, 83 Tat Chee Ave, Kowloon, Hong Kong, Peoples R China.
通讯机构：
[Rao, KP] C;City Univ Hong Kong, Dept Mfg Engn & Engn Management, 83 Tat Chee Ave, Kowloon, Hong Kong, Peoples R China.
摘要：
Hot extrusion of Ti–6Al–4V alloy has been studied using finite element simulation and the results are compared with those obtained experimentally. First, the constitutive behavior of the material and friction at the extrusion temperatures are established based on the results obtained through cylindrical and ring compression tests, respectively. While the flow stress below β transus temperature is expressed as a strain-dependent function, it is taken as strain-independent one at higher temperatures. The distribution of strain, temperature and effective stress has been simulated under different design and processing conditions. Simulation results show that heat generation due to deformation is significant (as much as 160°C) in the hot extrusion of Ti alloys, and it mainly occurs at the beginning of the extrusion process. This leads to reduction in flow stress which, in turn, leads to enlarged deformation zone. A fair agreement has been found between the experimental results and those obtained through simulations.
