Paper number 423

INFLUENCE OF THE INTERFACE STRENGHT ON LOCAL FAILURE PROCESSES IN FIBER REINFORCED COMPOSITES

C. Marotzke, A. Hampe, L. Qiao

Department of Polymers, Federal Institute for Materials Research & Testing (BAM),
Unter den Eichen 87, 12205 Berlin, Germany

Summary

The damage tolerance of fiber reinforced composites strongly depends on the microscopical failure processes arising at initiation and during propagation of macroscopical failure. In this paper, local failure processes such as fiber break with simultaneous radial cracks followed by debonding are investigated by means of model studies using the finite element method. The model is similar to that of a common fragmentation test. The influence of thermal prestresses as well as of interfacial friction is studied. Furthermore, the fiber type - glass and carbon fiber - and the fiber volume fraction is varied. It is shown that the fiber break releases a large amount of energy and is probably accompanied either by a matrix or an interface crack. Interfacial friction dissipates a large amount of stored strain energy due to radial compressive stresses acting in the interface.

Keywords

interface crack, energy release rate, fracture mechanics, debonding, thermal stresses, friction, finite element method (FEM).