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Thermographic test method and testing device for carrying out the test method

  • US 9,194,831 B2
  • Filed: 04/07/2011
  • Issued: 11/24/2015
  • Est. Priority Date: 04/08/2010
  • Status: Active Grant
First Claim
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1. A thermographic test method for locally resolving detection and identification of defects near a surface in a test object, the method comprising the acts of:

  • heating up a portion of the test object such that a thermal disequilibrium occurs between defective regions, affected by defects, and material of the test object that is free from defects, a defect-free surrounding area of a defective region not being heated up or heated up less intensely than the defective region, the surrounding area being located laterally with respect to the surface of the test object;

    recording a series of thermographic images one after another at a time interval within a heat propagation phase, which heat propagation phase begins when a lateral heat flow with respect to the surface of the test object from the locally heated-up defective region laterally into a surrounding area of the defective region manifests itself, each thermographic image representing a local temperature distribution in a surface region of the test object that is recorded by the thermographic image;

    determining positionally correctly assigned temperature profiles from the thermographic images, a temperature profile being a locally resolving profile, wherein different locations within the temperature profile are respectively assigned values of a measured variable representing the temperature at the respective location, and each positionally correctly assigned temperature profile being assigned to a same measuring region of the surface of the test object;

    determining variations over time of temperature values from the temperature profiles for a large number of measuring positions of the measuring region that are recorded by the temperature profiles; and

    evaluating the variations over time based on at least one evaluation criterion indicative of the lateral heat flow in the measuring region.

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