Developing an Infrared Flash Method for Bulk Material Characterization

Developing an Infrared Flash Method for Bulk Material Characterization

Aida Yoguely Cortés-PeñaMentors: Justin Jones & Michael ViensMaterials Engineering Branch/Code 541

Goddard Space Flight Center

Mechanical Engineering StudentGeorgia Institute of Technology

Materials Engineering Branch/Code 541

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Outline


BackgroundNon-Destructive EvaluationInfrared ThermographyResearch Objective

Part 1: Thermal Diffusivity MeasurementsAngstrom and Parker’s Method for Thermal DiffusivitySample PreparationResultsDiscussion

Part 2: Subsurface Defect DetectionArea Fraction MeasurementTemperature Line ProfileDerivative Image Analysis

Space Center Enrichment ActivitiesAcknowledgements References

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Non-Destructive Evaluation (NDE)


NDE: evaluate properties of a material without altering the article being inspected.

X-Ray Radiography (J. Jones)

Ultrasound Response for Adhesively Bonded Component (D.Polis) [1].

Infrared Thermography Image of the Orbiter’s heated tiles during re-entry [2].Infrared Thermography:

• detects radiation in the infrared (IR) range, 1 µm - 20 µm, of the electromagnetic spectrum.

• amount of IR radiation increases with temperature

[1] "Composite Crew Module: Nondestructive Evaluation Report ." 8 Sep. 2011. NESC-RP-06-019[2] Roebuck, Kevin. Terahertz Radiation: High-impact Emerging Technology - What You Need to Know:

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Infrared Thermography


• Infrared energy (thermal energy) directed towards an object is either reflected (ρ), transmitted (τ) through, or absorbed (α). • The intensity of the emitted infrared radiation depends on the material's emissivity (ε).• Emissivity: ability of a surface to emit energy by radiation.

ε =

Consists of a hole in a large encloser. Light entering the hole is reflected indefinitely and absorbed inside [4].

Radiation ability of a target [3]

• Black Body Source: absorbs all incident of radiation. ε = 1• High (0.95) Emissivity Stickers: Used to determine emissivity of an object by adjusting the value until the temperature on both surfaces match.

[3] "ThermoIMAGER TIM 160 Operators Manual ." MICRO-EPSILON. 25 Jul. 2012. [4] "Black body." 26 Jul. 2012. <http://en.wikipedia.org/wiki/Black_body>.

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Infrared Thermography


Research Objective:

•Thermal Diffusivity Measurements: develop an infrared technique for material characterizing of Thermal Diffusivity and Thermal Conductivity.

• Subsurface Defect Detection: Develop tools for composite inspections.

Applications:

• Maintenance of in-service aircraft

• Manufacturing of large aerospace structures.

Example: Inspection of the Space Shuttle wing leading edges Reinforced Carbon-Carbon system.

[5] "GPM Home | Precipitation Measurement Missions." Precipitation Measurement Missions | An international partnership to understand precipitation and its impact on humankind.. N.p., n.d. Web. 26 July 2012. <http://pmm.nasa.gov/GPM>. [6] "Magnetospheric Multiscale (MMS) Mission." Magnetospheric Multiscale (MMS) Mission. N.p., n.d. Web. 26 July 2012. <http://mms.gsfc.nasa.gov/>.

Magnetospheric Multiscale Mission [6]

Global Precipitation Measurement [5]

6Materials Engineering Branch/Code 541

Part 1: Thermal Diffusivity Measurements


[7] Angstrom’s Method of Determining Thermal Conductivity, Andrew M. Bouchard, Physics Department, The College of Wooster, Wooster, Ohio 44691, May 4, 2000[8] Parker, W. J.; Jenkins, J. J.; Abbott, G. L.; Butler, C. P. J. Appl. Phys. 1961, 32, 1679-1684.

Thermal Diffusivity Measurement Techniques

Thermal Diffusivity: represents how fast heat diffuses through a material. It is the measure of thermal inertia.

Angstroms Method: The thermal conductivity of a metal rod can be calculated by applying a heat pulse to one end while leaving the other end at room temperature, and measuring the temperature at two points as a function of time [7].

There is a need to reduce the length of time and the size of the sample required to make reliable measurements [8].

K = thermal conductivity ( W M-1K-1) ρ = density (kg m-3)Cp = specific heat capacity (J kg-1K-1)

α = = ( )Heat ConductedHeat Stored

kρ Cp

m2

s


Parker’s Flash Method: A high-intensity short-duration light pulse is absorbed in the front surface of a sample a few millimeters thick, and the resulting temperature history of the rear surface is recorded with an infrared camera [8].

• The thermal diffusivity is determined by the shape of the temperature vs. time curve.

L = uniform thickness (cm)

t05 = time required for the back surface to reach half of its maximum temperature rise.

α = -1.38 L2

π2 t05

2 3 4 5 6242730333639

Temperature vs. Time

Stycast 2850/Cat9MinMax

Time (s)

Tem

pera

ture

(°C)

Thermal Diffusivity Measurement Techniques

[8] Parker, W. J.; Jenkins, J. J.; Abbott, G. L.; Butler, C. P. J. Appl. Phys. 1961, 32, 1679-1684.

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Sample Preparation


• Diameter: 5 cm

• Thickness L = 0.1 cm

• ∆Temperature = 7 °C- 10 °C

Preparation:

• Fill mold with the adhesive.

• 24 hour over night stand

• 2 hour accelerated cure at 65 °C

Collaboration with Cindy Goode and Alejandro Montoya

• Epoxies are thermosetting polymers, they irreversibly cures by heat.• In flight hardware, encapsulants are used to avoid degassing.

• Stycast 2850 is the most commonly used thermally conductive encapsulant for flight hardware. However, it routinely disbonds during a thermal cycle.

• The thermal diffusivity of different epoxy's were measured to find a material that maintains high thermal conductivity with a balance in good bondage strength.

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Results


Adhesives Mix Thermal Diffusivity with BN (m2s-1)

Thermal Diffusivity without BN (m2s-1)

A Stycast 2850/Cat 9

N/A 3.5e-07

B Scotch Weld 2216 A/B

2.1e-07 0.7e-07

C Hysol 9309.2 A/B 1.6e-07 0.7e-07

D Arathane/Uralane 5750 A/B

1.4e-07 5.6e-07

A

B

C

D

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Discussion


1 3 5 7 92429343944

Temperature vs. Time

MinMaxt05

Time (s)

Tem

pera

ture

(°C)

The Hysol 9309.2 and Arathane 5750 are translucent materials, allowing the IR camera to capture the initial flash, affecting the quality of the thermal diffusivity measurements. To avoid this problem, the specimen should be opaque (non transparent and non translucent) to the pulse of light and to thermal radiation. Future work includes the implementation of a new algorithm to calculate the thermal diffusivity by using the cooling and heating part of the curve to correct for radiative heat loss [7].

[9] Baba T and Ono A 2001 Improvement of the laser flash method toreduce uncertainty in thermal diffusivity measurements Meas. Sci. Technol. 12 (2001) 2046–2057


Part 2: Subsurface Defect Detection


Global Precipitation Measurement (GPM) Solar Array Life Test Pane Life Test Panel

•The substrate is a sandwich panel composed of an aluminum honeycomb core coated on the backside, opposite to the solar cells, with white urethane paint.

•The paint delaminated the composite and the area fraction of this delamination was assessed.

•Delamination: Mode of failure for composite materials in which repeated stresses or impact causes layers to separate.

Image of the ply in the visible light spectrum.

Image Analysis and Processing:Area Fraction of Delamination

Collaboration with Dr. Dan Polis

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Image Analysis and Processing:Area Fraction of Delamination


Results: • The paint delaminated the composite.• Assessed the area fraction to be ~25% of the first ply.

IR Image shows presence of delamination.

Converted image to a 8-bit image with custom threshold.

Total area is the sum of each particle area.


Image Analysis and Processing:Temperature Line Profile

Collaboration with Dr. Dan Polis

•This composite tube simulates a part of the Magnetospheric Multiscale Mission (MMS) extending arm.

•Adhesives of different thicknesses were glued to a smooth surface and a rough surface. •Ultrasound and x-ray inspection detected that the thicker the surface the more debonding.•Using flash thermography, temperature line profiles were obtained to identify debonding areas.

Smooth Surface

Thinner Thicker

1

2

3 4

5

Rough Surface


Image Analysis and Processing:Temperature Line Profile

Smooth Surface

Thinner Thicker

1

2

3 4

5

Rough Surface

5 15 25 35 45 55 65 7526

28

30

32

34

36Temperature vs. Position

Circle 1 Smooth Sur-face

Position

Tem

pera

ture

(°C)

Area Fraction Image 05160749.jpg


Results: •Area fraction 32% Good Braze

Total Area: 0.535 inch^2Good Braze: Dark Area

Image of Brazing

Converted image to a 8-bit image with custom threshold.

Outline of Areas

Area Fraction32

Collaboration with Yury Flom

Area Fraction Image 05162234.JPG


Results: •Area fraction 47.275% Good Braze

Total Area: 0.535 inch^2Good Braze: Light Area Selection

Image of Brazing

Outline of LOB Areas

Custom Threshold

Area Fraction47.275

Collaboration with Yury Flom


• Aluminum Sheet with embedded numbers.

• Captured IR images and searched for number visibility when coated with white paint.

• Without paint, poor number visibility• With paint, no number visibility

Heating Up Cooling down

Without Paint

With White Paint

Heating Up Image Subtraction

Image Analysis and Processing:Visibility Surface Features

Collaboration with Tim Thomas and Debbie Thomas


Image Analysis and Processing:Video Derivative

Composite containing a different materials inside to simulate voids.

The location of the defects was identified from the IR images and by processing a video derivative.


• Use video derivative for subsurface defect detection




Grayscale IR Image.The location of the voids can be seen as the triangle and circular shapes.

1st Derivative

Shows the rate at which it is heating up or cooling down.

2nd Derivative:

Indicates time at which heat deposited at the surface encounters a subsurface interface. [9]

[10] Shepard S.M., “Flash Thermography of Aerospace Composites ”, Fourth Pan American Conference for NDT, October 2007, Buenos Aires, Argentina

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Thermographic Signal Reconstruction Technique


• Derivative image analysis allows for the reliable measurement of sample thickness, defect depth, and thermal diffusivity. In addition they are unique and invariant to ambience conditions, surface preparation or input energy.

Thermographic Signal Reconstruction (TSR) Technique

• Processes several hundred frames of raw data reducing it to a set of equations. • Advanced manipulation, such as obtaining the 2nd derivative, and using it to calculate the local wall thickness or flaw depth. • Inspection of low emissivity surfaces without surface preparation [7].

Future development of the infrared thermography capabilities includes the implementation of this TSR technique.

[10] Shepard S.M., “Flash Thermography of Aerospace Composites ”, Fourth Pan American Conference for NDT, October 2007, Buenos Aires, Argentina

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Space Center Enrichment Activities


Science Jamboree

Tour of building 7

Maryland Space Business Luncheon

Goddard Toastmasters

Goddard Dance Club

Materials Engineering Branch Tour

Branch Picnic

Goddard Day

Intern Open Mic

Poster Session

Sailing

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Acknowledgements

• Special thanks to my mentors Justin Jones and Michale Viens for their guidance and support this summer.

• Daniel Polis, Yury Flom, Timothy Thomas and Debbie Thomas for allowing me to assist them in their projects.

• Alejandro Montoya, Cindy Goode, Dewey Dove, Charles Powers, and Bruno Munoz for helping me acquire and learn to use the tools to setup my experiment.

• James Magargee for sharing his research experience and helping me grow in the field.

• Code 541 Staff

• Jeff Stewart for the Center tour.

• Hispanic College Fund and NASA Education staff for the excelent internship program.


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Thank You!


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References

[1] "Composite Crew Module: Nondestructive Evaluation Report ." 8 Sep. 2011. NESC-RP-06-019[2] "Infrared Astronomy." Cool Cosmos. N.p., n.d. Web. 26 July 2012. <coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/what_is_ir.html>. [3] "ThermoIMAGER TIM 160 Operators Manual ." MICRO-EPSILON. 25 Jul. 2012. [4] "Black body." 26 Jul. 2012. <http://en.wikipedia.org/wiki/Black_body>. [5] "GPM Home | Precipitation Measurement Missions." Precipitation Measurement Missions | An international partnership to understand precipitation and its impact on humankind.. N.p., n.d. Web. 26 July 2012. <http://pmm.nasa.gov/GPM>. [6] "Magnetospheric Multiscale (MMS) Mission." Magnetospheric Multiscale (MMS) Mission. N.p., n.d. Web. 26 July 2012. <http://mms.gsfc.nasa.gov/>. [7] Angstrom’s Method of Determining Thermal Conductivity, Andrew M. Bouchard, Physics Department, The College of Wooster, Wooster, Ohio 44691, May 4, 2000[8] Parker, W. J.; Jenkins, J. J.; Abbott, G. L.; Butler, C. P. J. Appl. Phys.1961, 32, 1679-1684.[9] Baba T and Ono A 2001 Improvement of the laser flash method toreduce uncertainty in thermal diffusivity measurements Meas. Sci. Technol. 12 (2001) 2046–2057[10] Shepard S.M., “Flash Thermography of Aerospace Composites ”, Fourth Pan American Conference for NDT, October 2007, Buenos Aires, Argentina<http://www.istec.nl/web/images/uploads/files/thermometer_1/man-thermoimager-tim-en.pdf.pdf>.


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Developing an Infrared Flash Method for Bulk Material Characterization