Vishay Measurements Group, Inc.

Vishay Intertechnology, Inc.

Vishay Precision Group, Inc.

Thomas P Kieffer

Robert Barry Watson

Felix Zandman

Rebecca L Showalter

Sharon Lee Karcher Harris

James I Hardy

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.

Fatigue life sensor for measuring repetitive loads applied to a structure based upon cracks propagating from crack initiation features of the sensor

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/&#xb0; F. to about 1000 ppm/&#xb0; F.

Resistance temperature detector with medium temperature coefficient and high linearity

A metal resistance strain gage with a high gage factor is provided. The electrical resistance strain gage includes a strain sensitive metallic element and has a chemical composition on a weight basis of approximately 63% to 84% Ni and approximately 16% to 37% Fe and a gage factor greater than 5.

High gage factor strain gage

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.

Strain gages with discrete electrical resistance trimming

A methodology for selecting and properly placing foil strain gages on a transducer in a Wheatstone bridge, which provides a more consistent creep response, especially when the transducer temperature is changed. A transducer includes a counterforce subjected to a predetermined physical load that provides tension and compression strains (positive and negative, respectively). The transducer also includes a plurality of strain gage grids that are operatively attached to the counterforce in the tension and compression strain areas of the counterforce and generate electrical signals. The plurality of strain gages are electrically connected in a Wheatstone bridge circuit where their electrical signals due to creep are cancelled.

Circuit compensation in strain gage based transducers

An improved strain gage and an improved manufacturing method are disclosed. The strain gage includes a semi-rigid substrate having a thickness of 3 to 30 mils, a resistive strain sensitive foil bonded to the semi-rigid substrate for providing a resistance varying with strain associated with a surface to which the strain gage is attached, a first and a second terminal operatively connected to the resistive strain sensitive foil, and an anti-static layer. The improved strain gage allows for reduced labor content in manufacturing by allowing use of modern automated electronic component manufacturing equipment.

Foil strain gage for automated handling and packaging

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.

Growing community of inventors

Wake Forest, NC, United States of America

Thomas P Kieffer