Volume 13, Issue 5, 2004

Modelling of the initial failure of CFRP structures by partial discretisation: a micro / macro-mechanical approach of first ply failure

Bodo Fiedler1, Stefan Holst1, Thomas Hobbiebrunken2, Masaki Hojo2, Karl Schulte

1 Polymer Composite Section, Technical University Hamburg-Harburg, Germany
2 Department of Mechanical Engineering, Graduate School of Engineering, Kyoto University, Japan

(Received 7/04; accepted 12/04)

ABSTRACT
The formation of transverse matrix cracks is the early failure in carbon fibre reinforced composites (CFRP). Unidirectional laminates with 90° fibre orientation were tested by transverse tensile tests and in situ under 3 point bending load in the scanning electron microscope (SEM). Finite element analysis were carried on the microscopic level hexagonal unit cell of fibre and matrix, as on the macroscopic level based on homogenized fibre and matrix properties as well. To link the micromechanical approach with the homogenized description of composite structures was done by transferring boundary conditions from one model to the other. The influence of the temperature on the Young’s modulus, the non-linear stress-strain behaviour and the strength of the matrix on the micro residual stresses and matrix failure was taken into account has been investigated in detail. Process induced thermal residual stresses and matrix failure of unidirectional carbon fibre reinforced composites (CFRP).