Behaviour of Fibre-Reinforced Composites under Dynamic Tension.
Abstract
This British report describes a small gas gun, capable of accelerating a projectile 1m long by 25.4mm dia. to about 50m/s, and an extended split Hopkinson pressure bar apparatus which have been designed and constructed for the tensile impact testing of fibre-reinforced composite specimens at strain rates of the order of 1000/s. Commissioning tests have shown equilibrium in the specimen to be attained at an early stage in the test and the effects of stress wave reflections in the specimen grip regions on the calculated stress-strain response to be negligibly small. A technique has been developed for the preparation of low volume fraction 'model' hybrid specimens, unidirectionally reinforced with a single layer of fibre tows, alternately of glass and of carbon fibres. Specimens have also been prepared from commercially supplied carbon/glass and carbon/kevlar epoxy plates with different stacking sequences for the carbon and glass or carbon and kevlar reinforcing mats to allow specimens with a range of hybrid fractions. In initial impact tests on the 'model' specimens tensile failures were obtained but with a trend for fracture close to the specimen/loading bar interface rather than in the centre of the parallel gauge section. Even so, a marked increase in fracture strength with strain rate was observed. Initial tests have also been performed on the woven reinforced carbon/glass hybrid specimens and the effect of hybrid fraction on the tensile modulus, fracture strength and fracture strain under impact loading has been determined. A preliminary study of the failure processes using optical and scanning electron microscopy has been undertaken.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 21, 1984
- Accession Number
- ADA150619
Entities
People
- John Harding
- K. Saka
Organizations
- University of Oxford