I tried in this way
clc
clear all
warning off
L=1.2; d=0.2; E=2*10^11;
syms f(a,w)
syms c
c=sqrt(d^2-2*w^2);
f(a,w) =(128*L^2*c^2*a^2)/(E*pi*d^2)*(sqrt((2*c)./(pi*a))*((tan((pi*w)./(2.*c)))*((0.923+0.199*(1-sin((pi*a)./(2*c))).^4)/cos((pi*a)./(2*c))))).^2;
I=integral2(f,0,0.015,0,0.105)

