Micromechanical modeling of nanocomposites considering debonding of reinforcements

This paper deals with a constitutive model of particulate-reinforced nanocomposites which can describe the debonding damage, elasto-plastic behavior of matrix and particle size effects on deformation and damage. An incremental damage model of particulate-reinforced composites based on the Mori-Tanaka's mean field concept, considering the particle size in nanoscale is further developed to consider the debonding of reinforcements in nanocomposites. The applicability of the proposed theory is investigated for nanocomposites consisting of Al2O3 nanoparticles with different size embedded in magnesium alloy (AZ31 and ZK60A) and pure magnesium (Mg) matrix. Based on the present model, analysis of stress-strain response for Al2O3-AZ31 nanocomposite under uniaxial tension is carried out. The effects of particle size and adhesive energy of nanoparticles at interface on stress-strain response of Al2O3-AZ31 nanocomposite is obtained. Moreover, in this paper the effect of debonding of reinforcements on effective Young's modulus and toughness of the particulate reinforced nanocomposites is demonstrated. When the debonding damage starts to occur, the stress-strain curve for the damaged nanocomposite deviate to lower stress from those for the perfect composite. The influences of adhesive energy at interface and particle size on the stress-strain curve are considerable. Composites with lower adhesive energy at interface and larger particle size have poor toughness due to lower area under the stress-strain curve. In addition, Progressive debonding leads to a loss of stiffness in nanocomposites. (C) 2014 Elsevier Ltd. All rights reserved.