Accession Number : ADA115724

Title :   Aerostructure Nondestructive Evaluation by Thermal Field Detection. Phase I. Fundamental Information and Basic Technique Development.

Descriptive Note : Technical rept.,

Corporate Author : VILLANOVA UNIV PA

Personal Author(s) : McLaughlin,P V ; McAssey,E V ; Emany,V R ; Koert,D N ; Spitzer,J M

PDF Url : ADA115724

Report Date : 25 May 1982

Pagination or Media Count : 122

Abstract : This report describes the results of efforts to evaluate and develop methods of flaw detection in laminated fiber composite aerovehicle structures using infrared radiation detection techniques. While not exhibiting the quantitative detection capabilities of other nondestructive evaluation (NDE) methods such as ultrasonics or neutron radiography, infrared thermography promises to provide a rapid method of damage detection in large structural surfaces. Two methods are described: externally applied thermal field (EATF) flaw detection where surface hot spots due to subsurface flaws are created by heating with a radiant heat source; and stress-generated thermal field (SGTF) flaw detection where 'hot spots' in viscoelastic composites are created at stress concentrations near structural flaws during high frequency, low magnitude cyclic loading. Analytical and experimental studies were performed on 8- to 32-ply graphite/epoxy laminates and 8- to 16-ply s2-glass/epoxy laminates containing delaminations and partial through-holes to evaluate and develop EATF thermography. Results show that the conduction method of heat application is unsatisfactory for NDE purposes, and that a radiant energy source in excess of one solar constant will be required for best results.

Descriptors :   *Composite materials, *Nondestructive testing, *Infrared detection, *Thermography, Defects(Materials), Stress concentration, Heat transfer, Viscoelasticity, Structural properties, Surface finishing, Fiber reinforced composites, Epoxy laminates, Glass, Graphited materials, Polyamide plastics, Hot spots, Test and evaluation, Radiant heating

Subject Categories : Laminates and Composite Materials
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE