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Title: Evaluation of Thin Kevlar-Epoxy Fabric Panels Subjected to Shear Loading

Abstract

The results of an analytical and experimental investigation of 4-ply Kevlar-49-epoxy panels loaded by in-plane shear are presented. Approximately one-half of the panels are thin-core sandwich panels and the other panels are solid-laminate panels. Selected panels were impacted with an aluminum sphere at a velocity of either 150 or 220 ft/sec. The strength of panels impacted at 150 ft/sec was not reduced when compared to the strength of the undamaged panels, but the strength of panels impacted at 220 ft/sec was reduced by 27 to 40 percent. Results are presented for panels that were cyclically loaded from a load less than the buckling load to a load in the postbuckling load range. The thin-core sandwich panels had a lower fatigue life than the solid panels. The residual strength of the solid and sandwich panels cycled more than one million cycles exceeded the baseline undamaged panel strengths. The effect of hysteresis in the response of the sandwich panels is not significant. Results of a nonlinear finite element analysis conducted for each panel design are presented.

Authors:
Publication Date:
Research Org.:
Army Research Lab., Hampton, VA (United States)
OSTI Identifier:
382974
Report Number(s):
N-96-24084; NASA-TM-111457; NAS-1.15:111457; AIAA-Paper-96-1367; NIPS-96-43737
TRN: 9624084
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Apr 1996
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; MATRIX MATERIALS; IMPACT TESTS; SHEAR PROPERTIES; EPOXIDES; FINITE ELEMENT METHOD; BUCKLING; HYSTERESIS; PANELS; SOLIDS; STRAIN GAGES; IMPACT STRENGTH

Citation Formats

Baker, D.J. Evaluation of Thin Kevlar-Epoxy Fabric Panels Subjected to Shear Loading. United States: N. p., 1996. Web.
Baker, D.J. Evaluation of Thin Kevlar-Epoxy Fabric Panels Subjected to Shear Loading. United States.
Baker, D.J. 1996. "Evaluation of Thin Kevlar-Epoxy Fabric Panels Subjected to Shear Loading". United States. doi:.
@article{osti_382974,
title = {Evaluation of Thin Kevlar-Epoxy Fabric Panels Subjected to Shear Loading},
author = {Baker, D.J.},
abstractNote = {The results of an analytical and experimental investigation of 4-ply Kevlar-49-epoxy panels loaded by in-plane shear are presented. Approximately one-half of the panels are thin-core sandwich panels and the other panels are solid-laminate panels. Selected panels were impacted with an aluminum sphere at a velocity of either 150 or 220 ft/sec. The strength of panels impacted at 150 ft/sec was not reduced when compared to the strength of the undamaged panels, but the strength of panels impacted at 220 ft/sec was reduced by 27 to 40 percent. Results are presented for panels that were cyclically loaded from a load less than the buckling load to a load in the postbuckling load range. The thin-core sandwich panels had a lower fatigue life than the solid panels. The residual strength of the solid and sandwich panels cycled more than one million cycles exceeded the baseline undamaged panel strengths. The effect of hysteresis in the response of the sandwich panels is not significant. Results of a nonlinear finite element analysis conducted for each panel design are presented.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1996,
month = 4
}

Technical Report:
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  • The low compressive strength of Kevlar reinforced composites causes concern about the ability of these materials to withstand bearing loads in bolted joints. This paper presents the results of an experimental investigation of the pin bearing load-deflection response of (0/90/+-45), (0/90) and (+-45) Kevlar 49 fabric/epoxy laminates. Laminate thicknesses from 0.075 in. to 0.300 in. were examined for pin diameters ranging from 0.125 in. to 0.500 in. Results of this study revealed three significant points: (1) a synergistic effect takes place in the (0/90/+-45) ply stacking sequence which results in higher yield and ultimate strengths than the (0/90) and (+-45)more » laminates; (2) bearing strength varies inversely with pin diameter, probably due to the statistical strength behavior of these materials; and (3) nominal bearing yield strengths are very low (10 to 20 ksi). It is concluded that joint designs should incorporate local reinforcement in bolted or pinned areas.« less
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