Dynamic compressive response of composite corrugated cores

Abstract

The dynamic out-of-plane compressive response of E-glass composite corrugated sandwich cores have been measured for impact velocities ranging from quasistatic to 175 ms-1. Laboratory scale sandwich cores of relative density ρ ≈ 33% were manufactured from 3D woven E-glass and stitched to S2-glass face-sheets via a double line of Kevlar yarn. Two variants of the sandwich cores were investigated: sandwich cores with the empty spaces between the corrugations filled with a PVC foam, and unfilled corrugations. The stresses on the rear faces of the dynamically compressed sandwich cores were measured using a direct impact Kolsky bar. The compression tests on both the corrugated cores and the parent strut wall material confirmed that these relatively high relative density corrugated cores failed by microbuckling of the strut wall material under quasistatic loading. Moreover, the foam filling did not have any significant effect on the measured responses. The peak stresses of both the strut wall material and corrugated cores increased approximately linearly with strain rate for applied strain rates less than about 4000 s-1. This increase was attributed to the strain rate sensitivity of the composite matrix material that stabilised the microbuckling failure mode of the E-glass composite. At higher applied strain rates the response was reasonably rate insensitive with compressive crushing of the glass fibres being the dominant failure mode. A simple model utilising the measured dynamic properties of the strut wall material accurately predicts the measured peak strengths of the filled and unfilled corrugated cores. © 2010. Journal of Mechanics of Materials and Structures.