One may wonder if this discussion has anything to do at all with force and /or torque sensors, however with little patience, not only some ambiguity will be removed, but also some very decisive eye-openers will be revealed when considering a sensor for an application.

The schematic (FIG. 1) is a simplified yet very accurate representation to what happens in a sensor, from the moment an event (e.g. impact force) is applied to the sensor till this event shows up on an indicator.

The event (the impact) causes a stress wave that travels in the sensor at the speed of sound longitudinally (at 5000 m/s) and laterally (at 3100 m/s) to reach strain gauge locations.

Assuming a sensor 10cm long, and 5cm diameter, gauges are in the middle of the sensor, then time “T” for stress wave (event) to reach gauges;