Accession Number : ADA165065


Title :   The Axial Compressive Strength of High Performance Polymer Fibers


Descriptive Note : Interim rept. Mar 1982-Dec 1984


Corporate Author : AIR FORCE WRIGHT AERONAUTICAL LABS WRIGHT-PATTERSON AFB OH


Personal Author(s) : DeTeresa, S. J.


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA165065


Report Date : MAR 1985


Pagination or Media Count : 211


Abstract : An experimental and theoretical study of the axial compressive strengths of high performance polymer fibers is undertaken. Compressive failure of these fibers manifests itself as kink band formation. Techniques permitting the application of small, measurable axial compressive strains to initiate kink banding in fine fibers are introduced. Tensile tests of compressively kinked poly(p-phenylene terephthalamide) (PPTA) fibers reveal only a 10% loss in tensile strength after application of compressive strains much greater than the critical strain required for kink band initiation. The concepts of compressive failure due to elastic microbuckling instabilities in axially compressed extended-chain polymers is proposed. Highly oriented polymer fibers are treated as a laterally interacting collection of fully extended chains. The critical stress required to buckle this collection of chains is calculated to be equal to the minimum longitudinal shear modulus of the fiber. This critical compressive strength is used as a prediction of the limiting value of fiber compressive strength. An excellent linear correlation between axial compressive strength and torsion modulus is measured for four extended-chain polymer fibers and for a graphite fiber. These fibers exhibit compressive strengths equal to approximately one-third of their respective torsion moduli. The relationship between torsion strains and axial normal strains in high performance polymer fibers is also investigated.


Descriptors :   *FIBERS , *POLYMERS , *STRENGTH(MECHANICS) , *COMPRESSIVE PROPERTIES , TEST AND EVALUATION , SHEAR PROPERTIES , STRESSES , TENSILE STRENGTH , TENSILE PROPERTIES , MODULUS OF ELASTICITY , FAILURE , GRAPHITE , STRAIN(MECHANICS) , LIMITATIONS , CHAINS , BUCKLING , STRENGTH(GENERAL) , VALUE , CORRELATION TECHNIQUES , COLLECTION , TORSION , CONTRACTION , FINE GRAINED MATERIALS.


Subject Categories : PLASTICS
      MECHANICS


Distribution Statement : APPROVED FOR PUBLIC RELEASE