Method for analyzing multi-layer materials from one-sided pulsed thermal imaging
View Patent ↗A method, apparatus, and computer program product provides automated analysis of thermal imaging data for multi-layer materials based upon a theoretical model of a multi-layer material system, which is solved numerically. The computer-implemented method effectively processes the volume heating effect for thermal barrier coatings (TBCs), since quantitative evaluation of TBC thickness and conductivity is particularly important. TBC thickness is a processing parameter and required to be monitored. TBC conductivity is a measure of TBC quality because it is directly related with TBC density/porosity, microcracking and interface cracks. Because this method is an imaging technology, it can be used for fast and 100% area inspection of larger TBC surfaces, such as combustor liners.
1. A computer-implemented method for automated analysis of thermal imaging data for multi-layer materials comprising the steps of:
a computer for
storing a plurality of model solutions for a multi-layer material system;
acquiring experimental thermal imaging data; said experimental thermal imaging data including test and sample parameters, said test and sample parameters including a heat capacity of each layer of the multi-layer materials;
fitting a model solution with the experimental thermal imaging data by adjusting the model parameters including thermal properties and thickness of each layer;
responsive to the model result matching the experimental thermal imaging data, identifying thermal properties and thickness parameters for the multi-layer materials; and
responsive to the identified thermal properties and thickness parameters for the multi-layer materials, constructing thickness, thermal conductivity, and absorption maps for the multi-layer materials.
2. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 1 further includes solving a theoretical model for a multi-layer material system.
3. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 2 wherein acquiring experimental thermal imaging data further includes reading said test and sample parameters, said test and sample parameters include imaging rate for the experimental thermal imaging data.
4. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 3 wherein said test and sample parameters include a number of layers, and for each layer of the multi-layer materials including a layer thickness, said heat capacity, and a layer conductivity.
5. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 1 wherein the step of fitting a model solution with the experimental thermal imaging data by adjusting the model parameters including thermal properties and thickness of each layer includes least-square fitting of a model solution with said experimental thermal imaging data.
6. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 1 wherein the step of fitting of a model solution with experimental thermal imaging data is used to determine thermal properties including conductivity and heat capacity.
7. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 1 wherein the step of fitting of a model solution with experimental thermal imaging data is used to determine absorption coefficient.
8. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 1 wherein the step of acquiring experimental thermal imaging data includes each layer being discretized into a plurality grids.
9. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 8 further includes automatically selecting time steps from the inputted experimental thermal imaging data to be analyzed.
10. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 9 further includes a measured time series of surface temperature at each pixel being fitted to a stored numerical solution to obtain best-fit parameters.
11. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 10 wherein said best-fit parameters provide conductivity and thickness.
12. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 10 wherein said best-fit parameters provide absorption coefficient.
13. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 1 wherein the step of acquiring experimental thermal imaging data includes providing variable time steps and nonuniform grid sizes in different material layers.
14. A computer-implemented method for automated analysis of thermal imaging data as recited in claim 1 wherein the step of acquiring experimental thermal imaging data includes incorporating finite flash duration and volume heat absorption effects.
15. Apparatus for automated analysis of thermal imaging data for multi-layer materials from one-sided pulsed thermal imaging comprising:
a data acquisition and control computer, said data acquisition and control computer storing a plurality of model solutions for a multi-layer material system;
said data acquisition and control computer for performing the steps of: acquiring experimental thermal imaging data; said experimental thermal imaging data including test and sample parameters, said test and sample parameters including a heat capacity of each layer of the multi-layer materials; fitting a model solution with the experimental thermal imaging data by adjusting the model parameters including thermal properties and thickness of each layer; and responsive to the model result matching the experimental thermal imaging data, identifying thermal properties and thickness parameters for the multi-layer materials; and responsive to the identified thermal properties and thickness parameters for the multi-layer materials, constructing thickness, thermal conductivity, and absorption maps for the multi-layer materials.
16. Apparatus for automated analysis of thermal imaging data for multi-layer materials as recited in claim 15 wherein the step of fitting of a model solution with experimental thermal imaging data is used to determine thickness, conductivity, heat capacity, and absorption coefficient.
17. Apparatus for automated analysis of thermal imaging data for multi-layer materials as recited in claim 15 includes said data acquisition and control computer for performing the step of acquiring experimental thermal imaging data includes reading test and sample parameters; said test and sample parameters including an imaging rate, a number of layers, a layer thickness, said heat capacity, and a layer conductivity.
18. Apparatus for automated analysis of thermal imaging data for multi-layer materials as recited in claim 15 wherein the step of fitting a model solution with the experimental thermal imaging data by adjusting the model parameters including thermal properties and thickness of each layer includes least-square fitting of a model solution with said experimental thermal imaging data.