Abstract: A passive deflection gauge 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 using a moveable or extensible core for measuring deflection. A stop moves the core only if a strain greater than the previously occurring 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 may be incorporated to prevent spurious movement of the core.

Abstract: Flaws in an electrically conductive sample object are detected by cancelling the magnetic field generated by a detection current passed through the sample object by passing the current back through an unflawed field cancelling object placed next to the sample object, and measuring the uncancelled field produced by any flaw, preferably with a superconducting quantum interference device (SQUID) magnetometer. Elongated objects such as tubes and rods are fed through a sleeve which forms the field cancelling object, with the current applied to the elongated member and passed to the field cancelling sleeve through sliding contacts.