DM&A have used cantilever gauges to studies blast waves since 1958. Some cantilevers are metal bars or wires fixed at one end, which bend from the fixed end in a blast wave in the direction of the air flow. Their bend angles can be used to measure the peak dynamic pressure and the dynamic pressure impulse of the blast wave. Other cantilevers are brittle and sensitive mainly to peak dynamic pressure, the value at the time of the shock front arrival.
Left:Two metal cantilevers after the passage of the blast wave from a 2500-ton ANFO explosion. The rods were initially vertical. The blast wave traveled from right to left. Bend angles measure peak dynamic pressure and dynamic pressure impulse, depending on the length, cross-section and material used. Right: Eight metal cantilevers after the passage of the same wave, this time travelling from left to right. This array of horizontal cantilevers was used to measure the differences in dynamic pressure impulse with height above ground in the flow boundary layer. The bend angle is effectively zero for the bottom cantilever and it increases with height. The red dots were added to illustrate the boundary layer profile.
Cantilevers are an inexpensive way to monitor explosions which might occur at unpredictable times in places like an explosive storage or work site, and can be left in place for many years without attention.