ISSN:
0272-8397
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The mismatch in thermoelastic properties between fiber and matrix in Kevlar 49 fabric-epoxy composites is shown to result in significant thermal stresses with cool down from processing temperatures. Cooling generates local transverse tensile stresses that can potentially initiate microcracking at ambient conditions. A temperature reduction also places the curved fiber in the fabric composite in axial compression. This compression adds to the bending strain in the fiber, resulting in significant local reduction of its inherently low compressive load-bearing capability. The combination of thermal stresses and external compressive loads that are below ultimate values can cause local compressive failure of the fiber. The kink bands formed as a result of compressive failure of Kevlar fiber are expected to cause debonding between fiber and matrix and, therefore, are also potential sites for crack initiation. Thus, thermal stresses can contribute to the initiation of at least two damage mechanisms that may severely limit the compressive and flexural fatigue strength of Kevlar fabric composites at and below ambient temperature.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pc.750090305
