On elastic modulus and biaxial initial yield surface of carbon nanotube-reinforced aluminum nanocomposites

• Elastic modulus and biaxial initial yield surface of CNT-reinforced Al nanocomposites are characterized.
• The study is performed based on the SUC micromechanical model.
• Effect of CNT/Al interphase on the behavior of nanocomposites is explored.
• Size of the initial yield surface in transverse-longitudinal loading is significantly affected by the interphase properties.
• Interphase is shown to have an important influence on the transverse elastic modulus.

A three-dimensional micromechanics-based analytical model is developed to investigate the elastic modulus and biaxial initial yield surface of aligned carbon nanotube (CNT)-reinforced aluminum (Al) nanocomposites. The Von-Mises yield criterion is used to obtain the yielding behavior of the nanocomposites under biaxial transverse-transverse and transverse-longitudinal loadings. The interphase region formed due to the interfacial reaction between the CNT and Al matrix is considered in the micromechanical modeling. The effects of geometry and material properties of the interphase and CNT volume fraction on the elastic modulus and biaxial initial yield surface of nanocomposites are studied. The elastic modulus obtained by the present model is in very good agreement with that reported from available molecular dynamics (MD) simulations and experiment. It is found that the effect of interphase is more important for the transverse elastic modulus of the nanocomposite as compared to the longitudinal elastic modulus. Also, the results reveal that the size of the biaxial initial yield surfaces of the nanocomposites, especially in transverse-longitudinal loading, is significantly affected by the interphase properties.