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Title: Failure modes and durability of kevlar/epoxy composites

Abstract

The fracture topographies of Kevlar 49/epoxy composite strands and multilayer composites in the form of pressure vessels are discussed in terms of the microscopic deformation and failure processes of the composites. The effect of resin ductility and fiber-matrix interfacial bond strength on mechanisms of fiber damage are considered. The failure of the Kevlar 49 fibers by a splitting process and the parameters, such as fiber fibrillation and macromolecular chain scission, that control such a process are discussed in relation to fiber and composite performance.

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA
OSTI Identifier:
5809228
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: SAMPE Q.; (United States); Journal Volume: 12:3
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COMPOSITE MATERIALS; FAILURES; PRESSURE VESSELS; ARAMIDS; EPOXIDES; FIBERS; FRACTURE PROPERTIES; INTERFACES; MICROSTRUCTURE; SCANNING ELECTRON MICROSCOPY; CONTAINERS; CRYSTAL STRUCTURE; ELECTRON MICROSCOPY; MATERIALS; MECHANICAL PROPERTIES; MICROSCOPY; ORGANIC COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; PETROCHEMICALS; PETROLEUM PRODUCTS; PLASTICS; SYNTHETIC MATERIALS; 360303* - Composite Materials- Mechanical Properties- (-1987)

Citation Formats

Morgan, R.J., Mones, E.T., Steele, W.J., and Deutscher, S.B.. Failure modes and durability of kevlar/epoxy composites. United States: N. p., 1981. Web.
Morgan, R.J., Mones, E.T., Steele, W.J., & Deutscher, S.B.. Failure modes and durability of kevlar/epoxy composites. United States.
Morgan, R.J., Mones, E.T., Steele, W.J., and Deutscher, S.B.. 1981. "Failure modes and durability of kevlar/epoxy composites". United States. doi:.
@article{osti_5809228,
title = {Failure modes and durability of kevlar/epoxy composites},
author = {Morgan, R.J. and Mones, E.T. and Steele, W.J. and Deutscher, S.B.},
abstractNote = {The fracture topographies of Kevlar 49/epoxy composite strands and multilayer composites in the form of pressure vessels are discussed in terms of the microscopic deformation and failure processes of the composites. The effect of resin ductility and fiber-matrix interfacial bond strength on mechanisms of fiber damage are considered. The failure of the Kevlar 49 fibers by a splitting process and the parameters, such as fiber fibrillation and macromolecular chain scission, that control such a process are discussed in relation to fiber and composite performance.},
doi = {},
journal = {SAMPE Q.; (United States)},
number = ,
volume = 12:3,
place = {United States},
year = 1981,
month = 4
}
  • The fracture topographies of Kevlar 49/epoxy composite strands and multilayer composites in the form of pressure vessels are discussed in terms of the microscopic deformation and failure processes of the composites. The effect of resin ductility and fiber-matrix interfacial bond strength on mechanisms of fiber damage are considered. The failure of the Kevlar 49 fibers by a splitting process and the parameters, such as fiber fibrillation and macromolecular chain scission, that control such a process, are discussed in relation to fiber and composite performance.
  • The technique of Laser Raman Spectroscopy has been applied in the study of aramid fibers, such as Kevlar 49, and aramid/epoxy interfaces. A linear relationship has been found between Raman frequencies and strain upon loading a single Kevlar 49 filament in air. Model composites of single Kevlar 49 fibers embedded in epoxy resins have been fabricated and subjected to various degrees of mechanical deformation. The transfer lengths for reinforcement have been measured at various levels of applied tensile load and the dependence of transfer length upon applied matrix strain has been established. Finally, by balancing the tensile and the shearmore » forces acting along the interface, the interfacial shear stress (ISS) distribution along the embedded fiber was obtained. 52 refs.« less
  • This paper treats the mechanical behavior of hybrid (Thornel P-55-Kevlar/Epoxy) composites under ambient conditions and under hostile environments. Interply (core/shell) and intraply tubes (5.75'' I.D.) were filament wound and NOL rings were machined from them. Apparently modulus and apparent strength were measured using the split D (ASTM D2290) test. The influence of boiling water exposure (2 hrs and 24 hrs) on short beam shear strength, apparent modulus, and apparent strength was also evaluated at room temperature and the fracture toughness for above configurations was measured at room temperature. Scanning electron microscopy was used to examine failure modes. 6 references, 4more » figures, 3 tables.« less
  • The response of Kevlar and graphite/epoxy composites subjected to simulated nuclear or laser thermal loads was measured. A solar furnace was used to radiantly heat samples at flux rates of up to 55 cal/sq cm per sec and total fluences of approximately 100 cal/sq cm. An iterative numerical technique was used to estimate the thermophysical properties of the materials by matching observed temperature-time histories with analytical predictions. Comparison of results obtained during this program with previously published data suggests that free stream velocity, which affects smoke blockage and char layer removal, is a critical design parameter. 8 references.
  • A mathematical model is developed from the principle of minimum potential energy to determine the longitudinal compressive response of unidirectional fiber composites. A theoretical study based on this model is conducted to assess the influence of local fiber misalignment and the nonlinear shear deformation of the matrix. Numerical results are compared with experiments to verify this study; it appears that the predicted compressive response coincides well with experimental results. It is also shown that the compressive strength of Kevlar/epoxy is dominated by local shear failure. 12 references.