Type of Document	Master's Thesis
Author	Taqieddin, Ziad N.
Author's Email Address	ztaqie1@lsu.edu
URN	etd-04062005-112716
Title	Damage Mechanics of Composite Materials Using Fabric Tensors
Degree	Master of Science in Civil Engineering (M.S.C.E.)
Department	Civil & Environmental Engineering
Advisory Committee	Advisor Name Title George Z. Voyiadjis Committee Chair Peter I. Kattan Committee Member Su-Seng Pang Committee Member Suresh Moorthy Committee Member
Keywords	damage mechanics composite materials fabric tensors
Date of Defense	2005-03-31
Availability	unrestricted
Abstract The major objective of this work is to relate continuum damage mechanics introduced through the concept of fabric tensors to composite materials within the framework of classical elasticity theory. A model of directional data-damage mechanics for composite materials is formulated using fabric tensors. In addition, a general hypothesis for damage mechanics is postulated. It is seen that the two available hypotheses of elastic strain equivalence and elastic energy equivalence may be obtained as special cases of the postulated general hypothesis. This general hypothesis is then used to derive the sought relationship between the damage tensor for composite materials and the fabric tensors. Two approaches to link the fabric tensors damage effect to the behavior of composite materials are adopted. The first approach is the continuum approach, which introduces damage with fabric tensors to the composite media; where the latter is treated as a homogenized material. Properties of the constituents are homogenized before the damage with fabric tensors is introduced. The second approach is the micro-mechanical approach, where damage with fabric tensors is introduced to the constituents rather than to the homogenized material. Within the framework of classical elasticity theory, both approaches should lead to equivalent results. Thus, a comparison between the two approaches is carried out to verify their equivalency. Damage evolution for both approaches is derived in a mathematically consistent manner that is based on sound thermodynamic principles. Numerical examples and application to the theory developed herein are presented. Micro-crack distributions in different constituents of the composite material are thoroughly investigated.
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