New explicit formulas for the effective piezoelectric coefficients of binary 0-3 composites

The explicit formula for the effective dielectric constant of binary 0-3 composites (Poon and Shin, J. Mat. Sc. 39 (2004) 1277-1281) is extended into two explicit formulas for the prediction of the elastic properties of macroscopically isotropic 0-3 composites. By combining them with the explicit effective dielectric formula into a calculation scheme (Wong et al., J. Appl. Phys. 90 (2001) 4690), we obtained two new explicit formulas for the prediction of the d(31) and d(33) values for binary 0-3 piezoelectric composites. These two explicit formulas are applicable even when the inclusion volume fraction is high. Comparing with existing experimental data, they are found to fit more favorably than those predicted by Wong et al. and others. Also, being explicit makes these formulas much easier to be embedded into other effective property calculations for binary 0-3 composite materials.