Pulsed electromagnetic nondestructive test method for determining volume density of graphite fibers in a graphite-epoxy composite material
Patent 4639669 Issued on January 27, 1987. Estimated Expiration Date: 
January 27, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
January 27, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2939073 3189817 3205485 3350634 3718855 3810005 3890564 Density sensing and controlling equipment Method and apparatus for measuring parameters of a conductive material which can be used in independently determining thickness and conductivity Non-contacting electromagnetic thickness gauge for sheet measurement having improved small distance sensitivity InventorsAssigneeApplicationNo. 06/535576 filed on 09/26/1983US Classes:324/239, Induced voltage-type sensor324/229, Thickness measuring324/639, Where energy is transmitted through a test substance73/32R, SPECIFIC GRAVITY OR DENSITY OF LIQUID OR SOLID73/597Velocity or propagation time measurementExaminersPrimary: Eisenzopf, Reinhard J.Assistant: Edmonds, Warren S. Attorney, Agent or FirmInternational ClassG01N 9/24 (20060101)AbstractA procedure for nondestructively determining a physical characteristic of a test object (10) involves introducing an electromagnetic energy pulse into the test object, and measuring elapsed time before the signature of a time-dependent function of the energy thereby propagated through the test object (10) reaches a value larger than a pre-set threshold value. For example, the volume density of graphite fibers in a graphite-epoxy composite material can be determined by introducing a pulse of radio-frequency electromagnetic energy into the composite material, and by measuring the elapsed time before the voltage signature of the energy propagated through the composite material reaches a value larger than the threshold value.Other References
Field of SearchPlural sensorsMaterial flaw testing Layer or layered material Noncoil type Material flaw testing Electrically energized nonforce type sensor Thickness measuring With backing member Opposed induced voltage sensors Plural magnetic fields in material Material flaw testing Plural sensors Induced voltage-type sensor With phase sensitive element With means to create magnetic field to test material Oscillator type Magnetic field detection devices With support for article Magnetic test structure elements | |
