Load indicating fastener systems method and apparatus

A load measuring apparatus comprising:

• a camera or laser, externally removably positionable and supportable on a portable detector head atop a fastener system to be visually or light beam coupled, respectively, to a bolt head of the fastener system along an axis parallel to the longitudinal axis of the fastener system configured and constructed for sensing a changing form caused by a deflection of a first portion of the bolt head relative to a second portion of the bolt head when the fastener is under strain without contacting the sensed portions of the bolt head, and
• a generating circuit responsive to the sensed changing form for providing an output signal indicative of a clamp load applied to the fastener.

A measuring device comprising a portable sensing head, having a first cylindrical capacitor plate fixedly supported in the portable sensing head, eternally removably positionable atop an integral head portion of a fastener system, and constructed and configured for directly capacitively coupling to a second cylindrical capacitor plate movably supported in the fastener system to form a capacitor for use in a circuit for detecting a changing gap, measured from a reference datum plane of the bolt head of the fastener system, the changing gap being produced in the fastener when the fastener system is under strain and causing a variance in the capacitive reactance of the detection circuit without the portable sensing head contacting the second movable capacitor plate.

A measuring device comprising a sensing circuit having a first capacitor plate externally removably positionable beside a deflectable washer mounted between an integral head portion of a fastener system and a workpiece, and constructed and configured for directly capacitively coupling to a second capacitor plate movably supported on the washer of the fastener system to form a capacitor for use in a circuit for detecting a changing gap between the first and second capacitor plates, the changing gap being produced when the fastener system is under strain and causing a variance in the capacitive reactance of the detection circuit without the sensing circuit contacting the second movable capacitor plate.

A measuring device comprising a portable sensing head, having multiple first capacitor plates fixedly supported in the portable sensing head, externally removably positionable atop an integral head portion of a fastener system, and constructed and configured for directly capacitively coupling each of the first capacitor plates to a common second capacitor plate movably supported on the fastener system to form multiple capacitors for use in a circuit for detecting a changing form of the bolt head of the fastener system, the changing form being produced in the fastener when the fastener system is under strain and causing a variance in the capacitive reactance of the detection circuit.

A measuring device comprising a portable sensing head, having first, spaced apart, capacitor plates fixedly supported in the portable sensing head, externally removably positionable atop an integral head portion of a fastener system, and constructed and configured for directly capacitively coupling the first capacitor plates to a second capacitor plate a portion of which is movably supported in the fastener system to form multiple capacitors for use in a circuit for detecting a changing gap, measured from a reference datum plane of the bolt head of the fastener system, the changing gap being produced in the fastener when the fastener system is under strain and causing a variance in the capacitive reactance of the detection circuit without the portable sensing head contacting the second movable capacitor plate.

A measuring device comprising a portable camera or laser which, when externally removably positioned and supported alongside of a bolt head and deflectable washer of a fastener system and visually or light beam coupled, respectively, to the bolt head and washer along an axis cutting the longitudinal axis of the fastener system at a substantial angle, detects a changing gap or form produced in the fastener when the system is under strain without contacting the sensed portions of the fastener undergoing significant relative movement.