Background from Ultra-low Frequency Isolation for Instruments
Up to now, vibration isolation for the light weight instruments is mainly based on the pneumatic supported platforms, which are effective with the resonance at the range of 1.5Hz to 4Hz, it is very difficult for them to tackle with the resonance less than 1.0Hz for the ultra-low frequency isolations.
The increase in the instrument weight generally results in the increased platform dimension, the increased energy consumption, the increased running and maintenance costs and the increased risks during the power breakage and the frequently occurring earthquakes.
The load capability and the mechanic stability of Steel Wire-rope Isolators are limited and it is not suitable for heavy duty applications where the load is much heavy. On the other hands, at the resonance the transmissibility is amplified by 3-6 times, it is impossible for the applications in the isolation platform.
Quasi-zero strength isolators based ob the metal elastomer are suitable not only for the ultra-low frequency isolation, but also for the heavy duty applications where the mechanic stability is required. Not only the quasi-zero strength isolators could be applied in ultra-low frequency isolation for instruments, large power engine isolation, but also the quasi-zero strength isolators could replace the existing steel wire-rope isolators, pneumatic air springs especially for the engines, car cabs、car seats etc..
Background from Earthquake Isolation in Building Structures
Dampers with a Flag-shaped hysteresis loop or the Self-centering characteristics are getting more and more focus from both the engineering designers and the researchers in institutes，mainly due to the shape of the Flag-shaped hysteresis loop which offers the dampers the special feature of self-centering ability.Engineering practice gets more benefits from the self-centering ability. It is a good example not only to absorb the main earthquake and also to absorb the residual earthquakes within the limited damper stroke. Tens of million of RMB spent for the manual reposition of the bridges could be saved by the automatic reposition of the bridges themselves.
Recent Cantilever Wall Systems in the building designing show the characteristic self-centering respon se, but the dimension is very large and the effective strokes are less than 3% with respect to the wall height. The building safety is still a problem if the wall, which also carries the building weight, is destroyed during the earthquakes, and the reconstruction cost is still sky-high.
With the change in the earthquake isolation concepts from the building non-collapse to building reposition and recovery after the earthquakes, the commercial opportunities are provided for the dampers, which are smart, non-destroyable, recoverable, functioned specially.
Dampers with the post-tensioning tendons or with a Smart Memory Alloy (SMA in short) are the typical examples. But dampers with the post-tensioning tendons provide the building structure with the very small displacement, and even dampers with the hyper-elastic SMA could only provide the building structure with a displacement of less than 8% of its length. On the other hands, both dampers have the limited life expectancy, which could not bear on the frequent earthquakes during tens and up to one hundred of years. Hyper-elastic SMA is very expensive compared with iron and steel, this limits its application in earthquake isolation of building structures. If a damper, which is not only hyper-elastic, but also long-lasting, exists, the revolution in the recoverable dampers will take place. It is the quasi-SMA dampers.
Working Principles
Applying load at the quasi-zero strength region of a Non-linear strength elastomer,to isolate the vibration in 3 degree of freedoms. Damping is provided by the friction between the supports and the non-linear strength elastomer.
Appearance of the Dampers/Isolators
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