Contribution of thermal stresses to the failure of Kevlar fabric composites

Journal Article · Wed Jun 01 04:00:00 EDT 1988 · Poly. Compos.; (United States)

DOI:https://doi.org/10.1002/pc.750090305· OSTI ID:6780676

Deteresa, S J; Nicolais, L

The effect of temperature changes on the compressive characteristics of Kevlar 49-epoxy composites were investigated. Using published data on the elastic properties of Kevlar 49 fiber and a typical epoxy matrix and the equation for the thermal expansion coefficient (TEC) developed by Schapery (1968) and Nairn (1985) for isotropic and transversely isotropic fibers, respectively, the temperature change required to cause compressive failure of the fiber was calculated for various volume fractions; it was found that, for typical unidirectional composites, thermally induced compressive failure of Kevlar fibers is of little concern. However, a temperature reduction places the curved fiber in the fabric-reinforced composite in axial compression, adding to the bending strain in the fiber. The combination of thermal stresses and external compressive loads that are below ultimate values by themselves can cause local compresive failure of the fiber. In addition, the kink bands formed as a result of compressive failure of Kevlar fiber are expected to cause debonding between fiber and matrix, and thus are also potential sites for crack initiation. 14 references.

• Research Organization: Lawrence Livermore National Lab., CA (USA); Napoli Universita, Naples (Italy)
• OSTI ID: 6780676
• Journal Information: Poly. Compos.; (United States), Journal Name: Poly. Compos.; (United States) Vol. 9; ISSN PCOMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ARAMIDS
COMPOSITE MATERIALS
COOLING
ELASTICITY
EPOXIDES
FAILURES
FIBERS
MATERIALS
MATRIX MATERIALS
MECHANICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICS
REINFORCED MATERIALS
STRESSES
SYNTHETIC MATERIALS
TENSILE PROPERTIES
THERMAL STRESSES
THERMOELASTICITY