An Analysis of the Elastic Response of MMC Laminated Tubes with Internal Fiber Cracks by the Generalized Method of Cells

Dr. Sarah Collins Baxter
University of Virginia 
Charlottesville, Virginia 

Sponsored by the Department of Engineering Mechanics

Date:  Friday, November 1, 1996
Time:  3:30 p.m.
Place:  306 Bancroft Hall
 

Previous experimental work has shown a lower effective elastic response for +/-45 (symmetric) SiC/Ti composite tubes, under axial and torsional loading, than expected.   A probable cause of this degradation is suggested by the considerable evidence which exists of both fiber/matrix debonding and fiber cracking in these off-axis piles.    In this work, the Generalized Method of Cells micromechanical model is used to calculate a constitutive equation for the composite material, in each ply, in the presence of fiber cracks of fiber/matrix debonds.  These constitutive equations are then used in the exact analytical solution of the problem of an arbitrarily laminated tube under axisymmetric or torsional loading. By employing GMC in the solution of the tube problem, predictions are made as to the degree of degradation of the elastic response of these tubes due to partial or full debonding of the fiber/matrix interface or pre-existing fiber cracks or a combination of both.  These theoretical predictions are compared to experimental results.