2001 #pdf #paper about Euler (buckled-column) springs for seismic isolation, also explaining #antisprings on p.3.
on 02015-11-092004 #pdf #paper about #antisprings for seismic isolation. Clarifies that YES, an antispring has a negative #stiffness coefficient. In this case they’re combining antisprings with regular springs to cancel out their stiffness and get near-zero restoring force for small displacements. They managed to get a resonant frequency of 0.3 Hz with #maraging steel #springs (to reduce creep), which doesn’t sound that great to me, but whatever.
on 02015-11-092007 #pdf #paper about #antisprings (negative-#stiffness springs) for seismic isolation, explaining how to improve their isolation by another order of magnitude with a counterweight rod thing that I don’t understand yet.
on 02015-11-09300nm displacements at 10Hz can be measured on their hall floor during the daytime due to human activity in the city, so they built this thing with “geometrical #antisprings”, described as “a tunable spring made by a crown of curved cantilever blades compressed each against the other” (negative #stiffness coefficient constructs?) to isolate their gravity-wave detector. They’re using electronic positive feedback to get “natural frequencies down to 0.2 Hz” and attenuate seismic noise by 80dB.
on 02015-11-09