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Wednesday, January 11, 2012

Radiography Testing For Fibre Reinforced Plastic & Composite

Radiography is a well-established production process with many variables in image formation and interpretation. The equipment performance, personnel qualifications and certification, test criteria, and test procedure scope must be identified and documented, if reliable and repeatable test results are to be achieved. Well-defined test criteria and high-quality reference images are needed to separate unacceptable material from acceptable materials with confidence. 

Radiography can be used with composite materials. It provides a permanent record of the test specimen in the image, reveals fabrication, assembly, and structural defects, and often suggests a corrective action in the process used. Digital data files can be easily communicated and shared. Digital data can be rescaled to accurately reconstruct engineering values of material density and size. Radiographic testing involves exposing a media to x-ray radiation that has penetrated the specimen of interest, developing an image from the media, and interpreting the image developed.

Radiographic testing can be applied to assure the maximum reliability of fibre reinforced composite products and bonded assemblies, both with and without honeycomb. It is complementary to ultrasonic inspection, in that these methods can detect different types of defects, and data from one method can often be used to help interpret results from the other. 

Existing processes involve tube-type constant potential or rectified radiation sources for production radiography, and many systems are capable of operating at low energy (< 50 kV).Radiographs are normally produced on a high contrast, small-g rain- size medium capable of meeting the flaw detection requirements of the applicable product inspection and acceptance specification. Film radiography typically uses the human eye for a detector. Films are interpreted by passing sufficient quantities of light through the film during observation. If the radiograph has sufficient contrast and spatial resolution, it will be possible to detect small variations within the specimen. Contrast variations of 2% and spatial details of 0.50 to 1.25 mm (0.020 to 0.050 in.) are easily detected in most fibre reinforced plastic and composite materials.
 Radiation cell for composites material inspection

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