Accession Number : AD0900244

Title :   Lightning Effects Relating to Aircraft. Part I. Lightning Effects on and Electromagnetic Shielding Properties of Boron and Graphite Reinforced Composite Materials.

Descriptive Note : Final rept. 15 Nov 69-15 Oct 71,

Corporate Author : GENERAL ELECTRIC CO PITTSFIELD MA HIGH VOLTAGE LAB

Personal Author(s) : Fisher, F. A. ; Fassell, W. M.

Report Date : JAN 1972

Pagination or Media Count : 222

Abstract : An investigation employing both destructive and nondestructive testing techniques affirms that lightning-produced currents adversely affect boron-and graphite- reinforced epoxy composites for aircraft. A majority of the coatings tested to determine their ability to protect composites in a lighting environment actually aggravated composite deterioration. To mitigate lightning damage, composite coatings must be either highly conductive or highly insulating. Limitations are identified that must be overcome before coatings of either type can be deemed acceptable. Several nondestructive testing evaluation techniques are compared. Acoustic impedance measurement holds the greatest promise, because it requires access to only one side of the material and it correlates well with physical inspections. This technique is potentially effective in locating cracks and delaminations. Resistance measurements are shown to be more meaningful for boron-based than for graphite-based materials. Other nondestructive material techniques, such as ultrasonic C-Scans, X-ray extractions, and sonic-vibrations, are found to be no better for lightning damage appraisal than ordinary visual inspections. (Author, modified-PL)

Descriptors :   *COMPOSITE MATERIALS, *LIGHTNING, *ELECTROMAGNETIC SHIELDING, *AIRFRAMES, GRAPHITE, BORON, COATINGS, LAMINATES, DAMAGE, TEST METHODS, NONDESTRUCTIVE TESTING, ACOUSTIC IMPEDANCE, REINFORCED PLASTICS, SANDWICH PANELS, AIRCRAFT PANELS, EPOXY RESINS, ELECTRIC CURRENT, VULNERABILITY.

Subject Categories : Aircraft
      Electrical and Electronic Equipment
      Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE