Kolanu, S R
(2014)
Numerical Study on Halting Crack Growth using Crack Stop Hole and Carbon Fibre Reinforced Polymer (CFRP) Laminates.
Masters thesis, Indian Institute of Technology Hyderabad.
Abstract
It is well known that drilling a hole ahead of crack tip is one of the most common techniques to prevent crack propagation in structures subjected to fatigue load. An adequate size crack stop hole is necessary to convert a sharp crack into a blunt notch there by preventing crack propagation. However, fatigue cracks typically occur at locations where drilling a crack-stop hole of required dimensions may not be possible due to geometrical constraints. In such situations, the crack may initiate again from the hole within its service life. Hence, there is a need to strengthen undersized crack-stop holes. In the present study, a combination of crack-stop hole and carbon fibre reinforced polymer (CFRP) overlays under static loads are studied numerically using finite element analysis (FEA) to evaluate its potential as a viable repair technique. A steel plate with an initial central crack subjected to static tensile loading is considered. A hole is modelled ahead of a crack tip and CFRP patches are applied on either side of the crack. The numerical analysis is performed using general purpose FEA ANSYS to evaluate the stress intensity factor at notch tip (NSIF). The material behaviour is assumed to be elastic in case of linear analysis and as a multi linear isotropic hardening material type for nonlinear
analysis.
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