Influence of in-plane shear on kink-plane orientation in a unidirectional
Artikel i vetenskaplig tidskrift, 2019
Kink-band formation is the governing failure mechanism for compressive failure of fibre reinforced composites.
Here, kink-plane orientation, describing the direction of kink-band formation, is studied using X-ray computed
tomography (CT). Unnotched unidirectional specimens with off-axis angles ranging from 0° to 20° are tested in
compression. The measured compressive strength is found practically constant for off-axis angles between 0° and
10°. For an off-axis angle of 15° the compressive strength drops dramatically. CT-results reveal this drop to be
consistent with a transition from out-of-plane to in-plane dominated kinking. Furthermore, results show the
kink-plane angle to be linearly dependant on off-axis angle, and hence in-plane shear stress. A three-dimensional
finite element model considering measured fibre misalignment angles through its volume is generated for numerical
analysis. Numerical predictions based on the LaRC05 kinking criterion are found to qualitatively capture
the experimentally observed effects of off-axis angle on kink-plane orientation.
C. Finite element analysis (FEA)
A. Carbon fibres