Eddy Current for Detecting Second Layer Cracks Under Installed Fasteners
Final rept. 1 Oct 1991-1 Nov 1993
NORTHROP CORP PICO RIVERA CA B-2 DIV
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The detection of second layer Cracks Under Fasteners CUF persists as an Air Force Logistics need. This work seeks to extend technology developed for detecting cracks in aluminum alloy substructure below graphite-epoxy skins, to structures with an aluminum first layer. Improvements to the design of the Northrop Low Frequency Eddy Current Array LFECA system are identified to improve sensitivity to CUFs in aluminum-over-aluminum structures. The probe core shape, dimensions, and coil configurations were optimized for detection with installed fasteners and metallic skin. A multiparameter analysis algorithm is applied to enable flaw discrimination from centering variations, edge responses and other sources of noise. The study also quantifies the capabilities and limitations of the LFECA system. Eddy current, Low frequency eddy current, Cracks, CUFs, Nondestructive Evaluation NDE.
- Attack and Fighter Aircraft
- Electricity and Magnetism