Due to its excellent stiffness and strength, carbon nanotubes (CNTs) are considered as candidates for reinforcement in composites. In the present work, the epoxy resin is used as the matrix whereas multi-walled carbon nanotubes (MWCNTs) with various diameters are used as the reinforcement. The composite is subjected to uniaxial tension and the effects of CNT weight fraction and CNT diameter on the mechanical properties of the composite are studied. Micromechanics models are employed to predict the Young modulus of MWCNT-reinforced composites. The predicted Young moduli are benchmarked with the experimental data of MWCNT-reinforced composites. The Young modulus and tensile strength of epoxy containing 5 wt% MWCNTs with a diameter less than 20 nm increase from 2.83 GPa and 25.67 MPa of pure epoxy to 4.56 GPa and 52.89 MPa, respectively.
The classical laminated plate theory is modified in the present work to study the nonlinear electro-mechanical coupling in smart electrostrictive actuators. An iterative and a closed-form solutions are developed to estimate the mechanical and electrical response of electrostrictive laminates due to electrical and/or mechanical excitation. Both the numerical and the analytic schemes give almost identical solutions, which shows that a nonlinear coupling term in the constitutive relation of electrostrictive materials is insignificant.