Summary of the OnScale Simulation using Flash Thermography

The simulation using Flash Thermography demonstrates the application of a heat flux to the surface of the steel plate. The simulation replicates the thermographic inspection techniques of using heat to analyze components.

Thermography is a powerful technique in NDE for rapid identification of defects in a range of materials and applications. Specifically, in Aerospace, flash thermography is capable of assessing large areas of composite material for sub-surface defects such as delaminations and disbonds.

When we ‘flash’ components with a heat lamp, an IR camera can be used to capture the thermal flux on the on the surface of the component. If a defect is present, the defect will create a change in the flux conditions and these can be seen as ‘hot-spots’ by the IR camera. Also, the cooling profile of parts provides additional information about the extent and classification of defect.

Technical details of the Flash Thermography simulation

We applied the heat flux as half a period of 5 Hz sine function to simulate the flash from a heat lamp. As time progresses, the plate cools to ambient temperature. If a defect is present, the surface temperature profile versus time will record a higher peak temperature and prolong the time to reach ambient temperature.

The dimension of the modeled steel plate was 20x20x5 mm with a defect size of the 3x3x0.2 mm.

OnScale’s thermal solver allow users to simulate both flash and lock-in thermography techniques with ease. Then, you can directly compare the time domain results that OnScale produces to real experimental results, making OnScale a valuable tool for fine tuning real thermographic inspections.

Computational Resources required for the OnScale simulation

  • Elements: the model used 62,500 elements for the thermal analysis
  • Processor: 2 x 8 core Intel Xeon E5 Workstation
  • RAM: 415 MB
  • Time required: 35 seconds

The simulation produces a number of useful outputs, including:

  • Temperature vs time graphs to compare temperature variation at multiple points
  • Video of temperature distribution through the steel plate with and without defect

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