Datasheets quote a safe overload, usually 150% of capacity, and an ultimate overload, usually 300%. Between the two the cell is expected to survive without a permanent change in calibration. Above the ultimate limit the element yields and the cell is scrap, although it may still produce a plausible signal.
Elastic versus plastic
Below yield the element behaves elastically: remove the load and the output returns to zero within the specified return-to-zero error. Slight overloads often leave a small offset that disappears after a few load cycles, because the gauge bond line relaxes. A persistent offset that does not change with cycling is permanent set and cannot be trimmed out reliably, since the sensitivity has usually shifted as well.
Field test after an event
Measure the bridge resistance and insulation resistance first; a shorted or open bridge ends the discussion. Then apply three cycles from zero to rated capacity and record zero and span each time. If the zero returns to within the datasheet return-to-zero error and the span repeats within repeatability, the cell is probably usable, but recalibrate before trusting it for trade or safety use.
Prevention
Mechanical stops set 10% above the rated load cost far less than a replacement cell, and they also protect against the shock loads that cause most real-world failures. On silo and hopper installations, check stops after every seismic event or vehicle impact.
Kevin Huang