Dynamic fiber debonding and frictional push-out in model composite systems: numerical simulations X. Bi a , Z. Li b,1 , P.H. Geubelle a, * , J. Lambros a a Department of Aeronautical and Astronautical Engineering, University of Illinois at Urbana-Champaign, 306 Talbot Laboratory, 104 S. Wright Street, Urbana, IL 61801, USA b Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA Received 22 June 2001; received in revised form 10 April 2002 Abstract This paper summarizes our recent progress on the experimental and numerical study of dynamic fiber debonding and frictional push-out in model composite systems. A modified split Hopkinson pressure bar system is adopted to perform dynamic fiber push-out experiments. A cohesive/volumetric finite element scheme is developed to capture the initiation and propagation of the crack along the fiber/matrix interface. Interface properties are extracted by comparison between experimental and numerical results. Details of the physical process are analyzed by investigating numerically the propagation and evolution of the axial stress along the entire system. The numerical method is applied to an aluminum/ epoxy model composite system. Finally, effects of several important parameters such as interfacial strength, interfacial fracture toughness, fiber/matrix friction coefficient and loading rate are investigated. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Fiber push-out; SHPB system; Cohesive finite element scheme; Debonding and frictional sliding 1. Introduction When a crack propagates in a composite ma- terial in a direction perpendicular to that of the reinforcing fibers, the failure process typically in- volves four basic mechanisms: matrix cracking, fiber/matrix debonding, fiber breakage and fiber pull-out. A substantial part of the energy is dissi- pated in the debonding and frictional sliding of the bridging fibers located behind the advancing crack front. Because of the important effect they have on the fracture toughness of a composite, these two processes have been the subject of extensive ex- perimental, analytical and numerical work. Most experimental investigations of the fiber debonding and pull-out/push-out process use model composites, in which the fiber diameter is chosen one to three orders of magnitude larger than that of the actual composite reinforcement to Mechanics of Materials 34 (2002) 433–446 www.elsevier.com/locate/mechmat * Corresponding author. Tel.: +1-217-244-7648; fax: +1-217- 244-0720. E-mail address: geubelle@uiuc.edu (P.H. Geubelle). 1 Present address: Abaqus Solutions Inc., Providence, RI, USA. 0167-6636/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0167-6636(02)00141-2