The crust behavior of fiber composite rods with a vinyl ester resin matrix
- Univ. of Michigan, Ann Arbor, MI (United States)
Unidirectional fiber composites structures crushed along the fiber axis have been shown capable of absorbing large amounts of energy. There is, however, an intrinsic instability in the energy absorbing process with such materials, and the objective of the present study was to determine its causes in composite specimens made with vinyl ester resin matrix. Rod-shaped specimens were crushed against steel plates of different shape. The material variables studied were fiber volume fraction, fiber diameter, fiber-matrix interface strength, and matrix yield strength. Test variables included specimen diameter, trigger geometry, crush plate geometry, and compressive hoop stress. The instability was described by the standard deviation of the instantaneous crush load from the mean. The instability was found to be fairly insensitive to all of the above variables. The specific energy absorption, on the other hand, depended on a number of the above variables. A microscopic examination of crushed specimens suggested the following: Sudden large drops in load were related to the formation of large kink bands. The load drop depended on the width of the band and the fractional cross-sectional area over which the band propagated. Formation of large kink bands may be due to material heterogeneity, resulting from voids and local fiber misorientation, or nonuniform load transfer across the crushed material. Stable crush can be obtained by the formation of a large number of small kink bands near the crush interface.
- OSTI ID:
- 577590
- Report Number(s):
- CONF-970431-; TRN: 98:000974-0021
- Resource Relation:
- Conference: United new generation vehicle conference and exposition, Detroit, MI (United States), 7-10 Apr 1997; Other Information: PBD: 1997; Related Information: Is Part Of Advanced composites - proceedings; PB: 639 p.
- Country of Publication:
- United States
- Language:
- English
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