Universitat Rovira i Virgili (URV)Tarragona, Spain · 2022

A floating slab for a transmission electron microscope

A 6,500 kg floating concrete slab on eight patented all-metal containers, tuned to 2 Hz, to isolate a JEM-F200 field-emission electron microscope.

1The challenge
Nanometre imaging in a building that moves
URV's microscopy and nanometric techniques area was installing a JEM-F200 field-emission transmission electron microscope. External vibration would compromise its specifications and the accuracy of its measurements. The ideal target was 1 Hz; the building structure limited it to 2 Hz.
2The solution
8 metal containers, cast into the slab
A 2 × 2 m pit, 600 mm deep, holds a 550 mm reinforced concrete slab that finishes flush with the floor. It rests on eight patented Silentflex anti-vibration containers, 100% metal and recyclable, whose dampers can be replaced after installation. The system was designed and simulated in MSC Adams.
3The result
2 Hz, confirmed in simulation
The dynamic simulation reached the 2 Hz natural frequency with transmissibility falling below 1 above it. The concrete was poured; installation and on-site technical verification were scheduled after the curing period.

Floor vibration reaching the microscopeIllustrative

Before · Slab on the building floorAfter · Floating slab at 2 Hz

Illustrative model: single-degree-of-freedom transmissibility of a 2 Hz slab for a 20 Hz floor disturbance. Not a site measurement.