Abstract: A sensor for measuring the fatigue life of a structure subjected to repetitive loads is disclosed. The sensor includes a backing material arranged for securement to the structure, and a foil arranged for securement to the backing material. The foil includes a conductive path along which electrical current flows at an initial resistance measured prior to the structure being subjected to repetitive loads. A crack initiation feature in the form of a notch is located on the conductive path. In response to repetitive loads applied to the structure, one or more cracks propagate from the crack initiation feature across the conductive path to cause electrical resistance to increase whereby the progression of fatiguing of the structure may be determined.

Abstract: A sensor for measuring the fatigue life of a structure subjected to repetitive loads is disclosed. The sensor includes a backing material arranged for securement to the structure, and a foil arranged for securement to the backing material. The foil includes a conductive path along which electrical current flows at an initial resistance measured prior to the structure being subjected to repetitive loads. A crack initiation feature in the form of a notch is located on the conductive path. In response to repetitive loads applied to the structure, one or more cracks propagate from the crack initiation feature across the conductive path to cause electrical resistance to increase whereby the progression of fatiguing of the structure may be determined.

Abstract: A strain gage comprises: a flat metallic element; a first layer, wherein the flat metallic element is laminated onto a first surface of the first layer and the flat metallic element covers a first part of the first surface of the first layer; and a second layer laminated onto a second surface of the first layer, wherein the second surface is opposite to the first surface, and a coefficient of thermal expansion (CTE) of the second layer is greater than a threshold value.

Abstract: An electrical resistance strain gage includes a uniformly distributed electrical resistance of the active measuring area and a discrete electrical trim resistance within an active measuring are. The trim resistance may include an electrical conductor in an electrically parallel circuit such that the electrical conductor may be selectively electrically removed from the strain gage to trim the electrical resistance of the strain gage. The trim resistance does not modify the active strain sensing area or uniform grid length.

Abstract: A resistance temperature detector (RTD) includes a temperature sensing circuit with a conductive element to receive an input signal and produce an output signal that is a function of temperature. The conductive element is formed from a metal having a temperature coefficient of resistance from about 10 ppm/° F. to about 1000 ppm/° F.

Abstract: A strain gage includes a strain gage grid of a conductive foil formed by a plurality of grid lines joined in series by end loops and first and second solder tabs electrically connected to the strain gage grid. The end loops of the strain gage are aligned off-axis with or at an angle relative to the measurement axis of the strain gage to thereby alter creep characteristics of the strain gage.

Abstract: An integral strain measurement layer for use in an assembly printed circuit board to provide for strain measurement on the printed circuit board. The strain measurement layer includes an insulating layer having a top surface and a bottom surface, a strain sensitive layer of metallic foil adhered to the top surface of the insulating layer for measuring strain associated with the printed circuit board, and a copper coating disposed on the strain sensitive layer of metallic foil.