Method for creating a structure for calibration or verification for non-destructive evaluation inspection
Inventors
JUAREZ, Peter D. • Leckey, Cara A. C.
Assignees
National Aeronautics and Space Administration NASA
Publication Number
US-10488369-B2
Publication Date
2019-11-26
Expiration Date
2037-04-06
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Abstract
Various embodiment methods to reliably and repeatedly replicate delaminations/disbonds and/or porosity defects in specimens/structures may include constructing the specimens/structures such that aerogel sheets and/or aerogel powders are placed or deposited in selected delamination/disbonding and/or porosity locations in the specimen/structure before the specimen/structure is cured. In various embodiments, the specimens/structures may be composites and/or bonded structures and the structures may be flat or curved. The aerogel sheets and/or aerogel powders may mimic delamination/disbonding and/or porosity defects in the cured specimens/structures. The cured specimens/structures including the replicated aerogel sheets and/or aerogel powders may be used for nondestructive inspection or other measurements, such as POD studies.
Core Innovation
The invention provides various embodiment methods to reliably and repeatedly replicate delaminations, disbonds, and porosity defects in specimens or structures by introducing aerogel sheets and/or aerogel powders at selected defect locations before curing. These aerogel materials mimic porosity and delamination defects in the cured composites or bonded structures, which may be flat or curved. The cured specimens including these aerogel inserts act as representative defects and may be used for nondestructive inspection techniques and Probability of Detection (POD) studies.
The problem addressed is that existing defect standards fail to represent porosity and delaminations effectively. Current methods lack well-controlled, representative, and transferable approaches to replicate these defects, with issues such as poor repeatability, limited inspection method applicability, or uncontrolled defect characteristics. Therefore, there is an urgent need for methods that provide accurate, reliable, and controlled replication of porosity and delamination defects in composites and adhesives that behave like real defects under diverse nondestructive evaluation techniques.
By placing aerogel at selected defect locations in specimens or structures during fabrication and curing, the invention achieves predictable and repeatable replication of difficult defects. Aerogel's unique properties, including low density and thermal effusivity similar to air, allow it to simulate gas gaps or bubbles akin to porosity and delamination defects. The invention enables creation of well-characterized defect standards suitable for multiple types of nondestructive inspection, including ultrasound and thermography, enhancing validation and calibration of inspection techniques.
Claims Coverage
The patent includes two independent claims that describe methods for fabricating composite or bonded structures and measurement structures with representative defects using aerogel.
Introducing aerogel at selected defect locations before curing
A method of selecting one or more defect locations prior to structure fabrication, placing aerogel at these locations in one or more materials including at least one curable material, and curing the material whereby the aerogel forms a representative defect in the structure.
Fabrication of measurement structures with aerogel replicating defects
A method of fabricating a measurement structure from layers and a curable material, disposing aerogel in the structure at selected locations before curing to replicate defects, followed by curing the material such that the aerogel mimics defects in the measurement structure.
The independent claims focus on forming representative porosity and delamination defects by placing aerogel sheets or powders at chosen defect sites during fabrication of composite or bonded structures and measurement structures, with curing step solidifying the defect simulation.
Stated Advantages
Provides accurate, reliable, and well-controlled methods to represent porosity and/or delamination defects in composites and adhesives.
Produces representative defects that behave like real defects under multiple nondestructive evaluation techniques such as ultrasound and thermography.
Enables predictable and repeatable replication of difficult defects, allowing better calibration and validation of inspection techniques.
Creates well-characterized defect standards enhancing the ability to perform Probability of Detection (POD) studies with higher accuracy.
Documented Applications
Use in composites and bonded structures, including flat and curved specimens.
Application in aerospace structures such as aircraft joints, skins, and spacecraft components including heat shields.
Application in oil and gas structures and automotive structures for defect simulation and inspection validation.
Use of specimens/structures with aerogel defects for nondestructive evaluation measurements, including ultrasound and thermography.
Enabling calibration, validation, and certification of nondestructive inspection techniques through creation of standard defect test articles.
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