Numerical estimation of effective elastic moduli of syntactic foams

The macroscopic elastic behavior of hollow microsphere filled composites, collectively known as syntactic foams, is studied using analytical and numerical methods. In the analytical model, the effective bulk modulus is first estimated, and then using solid harmonics appropriate for a uniaxial tensile field, the effective Poissonʹs ratio of the composite is determined. The macroscale material properties are also estimated using finite element (FE) analysis of representative unit cells. Using the analytical model, the applicability of unit cell FE methods in the estimation of effective elastic properties of the syntactic foam is assessed. The influence of particle distribution on the elastic moduli is studied using a full three-dimensional (3D) FE method. The moduli obtained for different distributions showed little scatter, and the average values of bulk modulus match closely with the analytical results.