[ Aerospace ]
[ Aerospace ]
Crack Image Quality Indicators
NASA is utilising Crack Image Quality Indicators ( CIQIs ) to optimise X-ray part inspections and develop a rapid , cost-efficient crack verification technique .
Text & images by NASA
Innovators at NASA Johnson Space Centre have developed a modelling and manufacturing technique that generates unique verification tools that simulate metal cracks within X-ray setup part-testing geometries . The tooling specimens , such as the example shown with its manufactured circular crack , also enable verification of x-ray radiography sensitivity for crack detection inspection setups . Given the complications associated with crack detection via x-ray radiography , steps must be taken to ensure detection reliability . Thus , a demonstration of crack detection with a specific crack demonstration tool is performed to estimate the probability of detection ( POD ). An ideal crack demonstration tool will match the alloy type , geometry , thickness , and expected crack morphology of the components to be tested . An inexpensive crack verification toolset that accurately
Benefits
•• Characterises crack detection capabilities
••
Enables development of crack detection requirements / standards
•• Optimises X-ray radiography test setups
•• Inexpensive to manufacture
••
Use of standardised crack verification toolsets can save time
Applications
•• Industrial x-ray radiography
•• Aerospace manufacturing
•• Gas and oil pipeline manufacturing
•• Gas turbine manufacturing
•• Prosthetic manufacturing
A tooling specimen with a manufaturered circular carck . Photo by NASA
represents crack-like discontinuities for various metal components would allow for reliable crack POD demonstrations while costing less and saving time over users having to generate their own fatigue crack specimens .
The technology X-ray radiography is commonly used for the detection of cracks in metal parts such as those used in the aerospace industry . A typical application is for weld inspection where volumetric flaws such as pores , inclusions and flaws resulting in volumetric features such as suck-back , and under-cut are detected . The x-ray inspection of welds is also meant to detect crack-like or tight flaws and cracks that provide linear indications . X-ray inspection reliability is based on POD of the desired minimum size cracks in suitable crack specimens . The demonstrated x-ray technique is then assumed to provide the same level of POD in actual part inspection . However , in many cases , the POD demonstration specimens and setup are not similar to that used for x-ray inspection of actual parts due to the lack of appropriate demonstration crack verification toolsets . The ideal demonstration toolset shall match the parts to be tested in alloy type , part geometry , thickness and expected crack morphology , target crack size , locations , and orientations . If a qualified CIQI tool is available at the time of part inspection , x-ray technique sensitivity for crack detection can be verified for the part inspection setup . A CIQI toolset could provide simulated known crack sizes and have the same material and geometry for x-ray inspection to that of the actual part . Ideally , the appropriate crack specimen can be used to make a CIQI tool , but manufacturing specimens with cracks of controlled morphology and size for different x-ray applications with different material alloys and thicknesses may be impractical and cost prohibitive . Therefore , cheap CIQI toolsets with representative cracklike discontinuities may be desired by industry . The Crack Image Quality Indicator ( CIQI ) is a technology readiness level ( TRL ) 6 ( system / sub-system model or prototype demonstrated in an operational environment ). The innovation is now available for companies to license ; note that NASA does not manufacture products itself for commercial sale .
Tube weld sample specimens with small dual-pore and large single-pore defects ( left ), and lack-of-fusion defects ( right ). Photo by NASA .
NASA is actively seeking licensees to commercialise this technology . For information , visit https :// technology . nasa . gov / patent / MSC-TOPS-87
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