Accession Number : ADA585430


Title :   Molecular-Level Study of the Effect of Prior Axial Compression/Torsion on the Axial-Tensile Strength of PPTA Fibers


Descriptive Note : Journal article


Corporate Author : ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE


Personal Author(s) : Grujicic, M ; Yavari, R ; Ramaswami, S ; Snipes, J S ; Yen, C ; Cheeseman, B A


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a585430.pdf


Report Date : 16 Jul 2013


Pagination or Media Count : 20


Abstract : A comprehensive all-atom molecular-level computational investigation is carried out in order to identify and quantify: (i) the effect of prior longitudinal-compressive or axial-torsional loading on the longitudinal-tensile behavior of p-phenylene terephthalamide (PPTA) fibrils/fibers; and (ii) the role various microstructural/ topological defects play in affecting this behavior. Experimental and computational results available in the relevant open literature were utilized to construct various defects within the molecular-level model and to assign the concentration to these defects consistent with the values generally encountered under prototypical PPTA-polymer synthesis and fiber fabrication conditions. When quantifying the effect of the prior longitudinal-compressive/axial-torsional loading on the longitudinal-tensile behavior of PPTA fibrils, the stochastic nature of the size/potency of these defects was taken into account. The results obtained revealed that: (a) due to the stochastic nature of the defect type, concentration/number density and size/potency, the PPTA fibril/fiber longitudinal-tensile strength is a statistical quantity possessing a characteristic probability density function; (b) application of the prior axial compression or axial torsion to the PPTA imperfect single-crystalline fibrils degrades their longitudinal-tensile strength and only slightly modifies the associated probability density function; and (c) introduction of the fibril/fiber interfaces into the computational analyses showed that prior axial torsion can induce major changes in the material microstructure, causing significant reductions in the PPTA-fiber longitudinal-tensile strength and appreciable changes in the associated probability density function.


Descriptors :   *AXIAL LOADS , *FIBERS , *MOLECULAR DYNAMICS , *POLYAMIDE PLASTICS , *TENSILE STRENGTH , *TORSION , COMPRESSION , STIFFNESS


Subject Categories : Textiles
      Plastics
      Atomic and Molecular Physics and Spectroscopy
      Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE