Topic: Mechanical & Industrial Engineering
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Continuum Damage-Healing Mechanics With Application To Self-Healing Composites
The general behavior of self-healing materials is modeled including both irreversible and healing processes. A constitutive model, based on a continuum thermodynamic framework, is proposed to predict the general response of self-healing materials. The self-healing materials response produces a reduction in size of micro cracks and voids, opposite to damage. The constitutive model, developed in the mesoscale, is based on the proposed Continuum Damage-Healing Mechanics (CDHM) casted in a consistent thermodynamic framework that automatically satisfies the thermodynamic restrictions.
The degradation and healing evolution variables are obtained introducing proper dissipation potentials, which are motivated by physically based assumptions. An efficient three-step operator slip algorithm, including healing variables, is discussed in order to accurately integrate the coupled elastoplastic-damage-healing constitutive equations. Material parameters are identified by means of simple and effective analytical procedures. Results are shown in order to demonstrate the numerical modeling of healing behavior for damaged polymeric matrix composite. Healed and not healed cases are discussed in order show the model capability and to describe the main governing characteristics concerning the healed systems evolution.
Structural material behavior is dominated by irreversible processes development, such as damage and residual strain release, which reduce the structural integrity and service life. Damage and irreversible deformation phenomena affect the integrity of the material, by creation and coalescence of micro cracks, fiber breaks, fiber matrix debond, etc. The evolution of internal defects produces structural degradation, with consequent stiffness and strength reduction (Dvorak 2000). Once micro-cracks development reaches the critical state, no further stress redistribution occurs, and the material rapidly reaches the failure condition (Aboudi 1991, Pindera 1992; Piggott et al. 2000; Herakovich 1999).
The constitutive relationships and evolution equations define a non-linear differential problem, which is solved by means of a proper numerical algorithm. The main equations are integrated by Euler-backward technique, which is a stable numerical procedure to determine the actual solution by an incremental/iterative method. In particular, an elastic-predictor and Damage-Healing-Plasticity corrector integration scheme is used to solve the incremental nonlinear constitutive equations.
Source: www.mae.wvu.edu
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