%求出b的方程(-a<x<-b,-b<y<b)
clc;
format long e
syms x;
syms y;
syms p
syms h;
syms a;
syms b;
p=4;
h=5;
pi=3.14;
E=1.3e5;
a=125;
d=5;
v=0.28;
D=(E*h^3)/(12*(1-v^2));
w=d*(cos(pi*(x+b)/(2*(a-b))))^2;
Wx=diff(w,'x');
Wy=diff(w,'y');
Wx2=diff(w,'x',2);
Wy2=diff(w,'y',2);
Wxy=diff(Wx,'y');
U0=(Wx2 + Wy2) ^ 2-2*(1-v)*(Wx2*Wy2-(Wxy)^2);
U1=int(U0,x,-a,-b);
U2=int(U1,y,-b,b);
U=D*U2/2;
V0=p*w;
V1=int(V0,x,-a,-b);
V=int(V1,y,-b,b);
e1=simplify(U)
e2=simplify(V)
clc;
format long e
syms x;
syms y;
syms p
syms h;
syms a;
syms b;
p=4;
h=5;
pi=3.14;
E=1.3e5;
a=125;
d=5;
v=0.28;
D=(E*h^3)/(12*(1-v^2));
w=d*(cos(pi*(x+b)/(2*(a-b))))^2;
Wx=diff(w,'x');
Wy=diff(w,'y');
Wx2=diff(w,'x',2);
Wy2=diff(w,'y',2);
Wxy=diff(Wx,'y');
U0=(Wx2 + Wy2) ^ 2-2*(1-v)*(Wx2*Wy2-(Wxy)^2);
U1=int(U0,x,-a,-b);
U2=int(U1,y,-b,b);
U=D*U2/2;
V0=p*w;
V1=int(V0,x,-a,-b);
V=int(V1,y,-b,b);
e1=simplify(U)
e2=simplify(V)