Determination of Dynamic Delamination Toughness of a Graphite-Fiber/Epoxy Composite Using Hopkinson Pressure Bar

Authors

Xiangfa Wu, Department of Engineering Mechanics, University of Nebraska-LincolnFollow
Yuris A. Dzenis, Department of Engineering Mechanics, University of Nebraska-LincolnFollow

Date of this Version

5-12-2005

Comments

Published in Polymer Composites 26 (2005), pp. 165–180; doi 10.1002/pc.20093 Copyright © 2005 Society of Plastics Engineers; published by John Wiley & Sons. Used by permission. http://www.interscience.wiley.com

Abstract

Modified dynamic three-point-bending and compact shearing test configurations based on Hopkinson pressure bar (HPB) and crack detection gage (CDG) (Vishay Intertechnology, Inc) were used for the determination of the dynamic mode I and mode II delamination-initiation toughness of a unidirectional graphite-fiber/epoxy composite made of P7051S-20Q-1000 prepregs (Toray Composites America). The transient loading history was recorded precisely by the HPB installed with a highresolution digital oscilloscope, and the crack initiation and delay time were captured using the CDG. By means of dynamic finite-element analysis (FEA) of the impact processes with the loading history and crack initiation time as input, the critical dynamic stress intensity factors (DSIFs) (K_IDC/K_IIDC) were extracted from numerical results of the crack opening displacements (CODs). Results show that under the present transient loadings, the K_IDC value is about 80–90% of the static one, while the K_IIDC value is nearly unchanged. Dynamic failure mechanisms of the composite specimens were evaluated by fractography using a scanning electron microscope (SEM).