Numerical Study and Experimental Validation of Effect of Varying Fiber Crack Density on Stiffness Reduction in CFRP Composites
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Representative volume element (RVE) has commonly been used to predict the stiffness of undamaged composite materials using finite element analysis (FEA). However, never has been an independently measured true microstructural damage quantity used in FEA to predict composite stiffness. Hence, in this work, measured fiber crack density in unidirectional fiber composite (generated using controlled fatigue loading) was used to predict reduction in stiffness using a RVE. It was found that the stiffness changes with change in depth of the volume element along the fiber direction and asymptotically reaches a constant value beyond a critical length called representative depth. It was argued that this representative depth should be more than the minimum of two characteristic length scales, twice of ineffective length and average length of broken fibers. Effective stiffness obtained from FEA of the optimum-sized RVE was in excellent agreement with the experimental results for given microstructural damage state.
Keywordsadvanced characterization composites fatigue finite element analysis microstructural damage organic matrix representative volume element stiffness
The authors gratefully acknowledge the support provided for this work by the “National Centre for Aerospace Innovation and Research, IIT-Bombay, a Department of Science and Technology, Government of India, The Boeing Company and IIT Bombay Collaboration”; and the “Ministry of Textiles, Government of India”.
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