High strain rate compression testing of Kevlar 29/polyethylene composite with very high fiber volume fraction

Abstract

Experimental results are presented for the mechanical properties of Kevlar 29 / Polyethylene thermoplastic matrix composite in compression at high strain rates. Results of quasi static tests are also presented. Fiber volume fraction (Vf) in the composite is 85%. The composite is quasi - isotropic. All the tests were conducted at room temperature. High strain rate tests were conducted using a Split Hopkinson Pressure Bar (SHPB) and the quasi static tests were conducted in an Instron machine. The yield stress and yield strain are presented for strain rates varying from 400/s to 1535/s in one of the in-plane (i.e. 1 and 2 directions) directions and from 1010/s to 2165/s in the 3 direction. The data from the 29 dynamic tests and 6 quasi static tests were statistically analyzed and discussed in some detail. The dynamic test results are represented by equations wherever possible and compared to the static test results. Significant increase in compressive yield strength and decrease in yield strain are observed at high strain rates compared to those of the material at quasi static tests.