A passive deflection gauge (20) to detect peak deflection in a structural material or system since a given time is disclosed. The gauge includes any type of mechanical deflection sensor (21) using a moveable or extensible core (28) for measuring deflection. A stop (23) moves the core only if a strain greater than the previously occuring maximum strain is present in the structural material or system. Any other movement of the stop will not move the core. Furthermore, a friction member (40) may be incorporated to prevent spurious movement of the core.
