Design, analysis, and manufacture of large linear motor damper for structural vibration control system

Summary form only given as follows. sWith the introduction of high-energy product rare-earth cobalt magnets and especially NdFeB permanent magnets (PMs), the moving coil linear oscillatory actuator with the high power are being developed. However, the manufacture of a large PM linear actuator is difficult because of the limit of PM size and the attraction and repulsion at the assembly of PM. This paper deals with the design, analysis and manufacture of the linear motor damper (LMD) with the high power for the structural vibration control. LMD consists of the NdFeB magnets, a coil-wrapped nonmagnetic hollow rectangular structure, an iron core as a pathway for magnetic flux, and mechanical spring. The PM field part composed of magnet modules and iron yoke, is moving mass itself, 1500 kg. LMD therefore has a simplified structure and requires a few elements in the driving system, being compared with a rotary motor damper and a hydraulic damper. The control parameters and the frequency response were extracted from the dynamic experiments. Performance tests of vibration control system were carried out on the test structure of about 120 tons subjected to sinusoidal or random base excitation. From these tests, it was confirmed that the acceleration level of the structure was drastically reduced near the resonant region.