where a; b and c are the coefficients of proportionality. The normalized SIFs, EDIFs and ERRs with the conditions of
a=W ¼ 0:4; H=W ¼ 0:5 andW1=W ¼ 0:5 are shown in Tables 5–7, respectively. It is shown that the values of fracture parameters
decrease monotonously as a and b increase; the values of normalized SIFs and ERRs decrease as c increases, while that
of normalized EDIFs increase as c increases. The phenomena indicate that the elastic and piezoelectric constants have the
same effect on all of the fracture parameters, while the dielectric permittivity does not.