Effective Thermal Diffusivity Measurement Using Through-Transmission Pulsed Thermography: Extending the Current...

Area of Science:

• Materials Science
• Non-Destructive Testing (NDT)
• Thermal Analysis

Background:

• Through-transmission pulsed thermography (PT) is an effective NDT method for material thermal diffusivity assessment.
• PT in transmission mode offers superior defect resolution and deeper defect detection compared to reflection mode.
• Current thermal diffusivity measurement systems are often costly and require stringent experimental conditions.

Purpose of the Study:

• To present a simple, repeatable laboratory methodology for determining thermal diffusivity using through-transmission PT.
• To compare the performance of Parker's half-rise equation with a new least squares fitting (NLSF) algorithm for thermal diffusivity estimation.
• To optimize experimental parameters like flash energy and sample thickness via design of experiments (DOE).

Main Methods:

• Implementation of a through-transmission pulsed thermography (PT) setup.
• Integration of finite element analysis (FEA) with laboratory experiments.
• Application of a full-factorial design of experiments (DOE) to optimize parameters.
• Estimation of thermal diffusivity using Parker's equation and the new least squares fitting (NLSF) algorithm.

Main Results:

• The NLSF algorithm demonstrated greater robustness against noise and higher repeatability in thermal diffusivity measurements compared to Parker's method.
• The NLSF algorithm successfully estimated thermal diffusivity, input flash energy, reflection coefficient, and data capture time delay.
• Design of experiments identified optimal flash energy and sample thickness for reliable thermal diffusivity estimation.

Conclusions:

• The developed methodology provides a simpler and more cost-effective approach to thermal diffusivity measurement using through-transmission PT.
• The NLSF algorithm is a more efficient and reliable technique for thermal diffusivity estimation, offering additional parameter insights.
• This work enhances the practical application of through-transmission PT for material characterization.