Development of a Non-destructive Inspection Technique for Advanced Composite Materials Using Cholesteric Liquid Crystals.
Abstract
A new, relatively simple and inexpensive non-destructive inspection technique for advanced composite materials is proposed and its feasibility is demonstrated. This technique uses encapsulated cholesteric liquid crystals to sense small temperature differences which result from nonuniform heat transfer through composites. Discontinuities in heat transfer evidenced by contrasting surface color patterns indicate material discontinuities, i.e. flaws. Preliminary investigations into the thermal conductivity of a .041 in. thick graphite/epoxy laminated panel in the direction normal to the composite laminae and in the direction parallel to the laminae are described. The coefficients of conductivity in the two directions were found to differ by an order of magnitude. A qualitative test of the technique in locating embedded teflon triangles is reported, and a design for a testing device is proposed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1976
- Accession Number
- ADA032322
Entities
People
- Robert Troy Schaum
Organizations
- Naval Postgraduate School