Title: Effective mechanical properties of “fuzzy fiber” composites

George Chatzigeorgiou,
Dept. of Civil Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece

Gary Don Seidel,
Dept. of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University, 228 Randolph Hall (0203) Blacksburg, VA 24061, USA

Dimitris C. Lagoudas
Dept. of Aerospace Engineering, Texas A&M University, College Station, TX 77843, USA

Composites Part B: Engineering -- 2012 -- Volume 43, Issue 6, pp. 2577-2593

Abstract
In this paper we investigate the mechanical behavior of carbon fiber composites, where the carbon fibers are coated with radially aligned carbon nanotubes. For this purpose we develop a general micromechanics method for fiber composites, where fibers are coated with radially aligned microfibers (“fuzzy fiber” composites). The mechanical effective properties are computed with a special extension of the composite cylinders method. The in-plane shear modulus is determined using an extended version of the Christensen’s generalized self consistent composite cylinders method. The proposed methodology provides stress and strain concentration tensors. The results of the method are compared with numerical approaches based on the asymptotic expansion homogenization method. The combination of composite cylinders method and Mori–Tanaka method allows us to compute effective properties of composites with multiple types of “fuzzy fibers”. Numerical examples of composites made of epoxy resin, carbon fibers and carbon nanotubes are presented and the impact of the carbon nanotubes length and volume fraction in the overall composite properties is studied.

Key words: A. Carbon fibre; A. Polymer–matrix composites; C. Micro-mechanics; Carbon nanotubes