This code is plotting incorrectly. The plot in the x-axis should range from 0 to 1 and right now it is -1 to 1.
Also, no curve is being plotted with the code below.
E_3c = (E_f*f_f)+(E_m*(1-f_f));
G_3c = (((f_f/E_f)+((1-f_f)/E_m))^-1);
ds_db = ((6/5)*(E_3c/G_3c)*((t_L)^2));
plot(f_f,ds_db, 'Color', 'blue');
title('Contribution of Shear to Beam Deflection vs. Fiber Volume Fraction')
xlabel('Volume fiber fraction, f_f')
ylabel('Contribution of Shear to Beam Deflection, ds/db [MPa]')