Test circuit with sense elements having associated and unassociated primary windings

US8222897B2 · kind B2 · utility

Assignee

• JENTEK Sensors, Inc. · US

Inventors

• Yanko K. Sheiretov · Waltham, US
• Neil J. Goldfine · Newton, US
• Todd M Dunford · Amherst, US
• Scott Denenberg · Boston, US
• David C. Grundy · Reading, US
• Darrell E. Schlicker · Watertown, US
• Andrew P. Washabaugh · Chula Vista, US
• Karen E. Walrath · Arlington, US

Key dates

• Filing date: Jun 12, 2008
• Grant date: Jul 17, 2012
• Expiry date: Jan 19, 2031

Classification

• Technology area (CPC G): Physics
• CPC primary: G01L5/164
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An apparatus for the nondestructive measurement of materials that includes at least two layers of electrical conductors. Within each layer, a meandering primary winding is used to create a magnetic field for interrogating a test material while sense elements or conducting loops within each meander provide a directional measurement of the test material condition in different orientations without requiring movement of the test circuit or apparatus. In a bidirectional implementation the meanders are oriented 90° apart while in a quadridirectional implementation the meanders are orientated at −45, 0, 45, and 90°. Multidirectional permeability measurements are used to assess the stress or torque on a component. These measurements are combined in a manner that removes temperature effects and hysteresis on the property measurements. This can be accomplished through a correction factor that accounts for the temperature dependence. After the correction, the permeability measurement is then used to assess the local stresses and strains in the material of interest.