i want to solve this function and get the omega value,but i don't know how to use it ,please.

Question

peng haochen 2021-7-2

0
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https://ww2.mathworks.cn/matlabcentral/answers/870418-i-want-to-solve-this-function-and-get-the-omega-value-but-i-don-t-know-how-to-use-it-please

回答： Shubham Khatri 2021-7-5

clear all;clc;

for omega=1:100

syms omega a h g del eps

tb = 3;

lb = 10;

wb = 5;

E = 205e9;

rho = 7850;

I =((tb^3)*wb)/12;

pi =3.1416

A =tb*wb

K =0.833

G = E/2/(1+0.28)

a^4=(rho*A*omega^2)/(E*I)

h^4=(1-(rho*I*omega^2)/(K*A*G))*a^4

g^2=((a^4*I/A)+rho*omega^2/(K*G))

del=((h^4+(g^4)/4)^0.5+(g^2)/2)^0.5

eps=((h^4+(g^4)/4)^0.5-(g^2)/2)^0.5

F1 = ((del)^5*(sin((del)*lb))^2+(del)^2*(eps)^3*sin((del)*lb)*sinh((eps)*lb)-(eps)^2*(del)^3*sin((del)*lb)*sinh((eps)*lb)+(eps)^5*(sinh((eps)*lb))^2)...

-((del)^5*(cos((del)*lb))^2+(del)^2*(eps)^3*cos((del)*lb)*cosh((eps)*lb)-(eps)^2*(del)^3*cos((del)*lb)*cosh((eps)*lb)+(eps)^5*(cosh((eps)*lb))^2)

fsolve(F1,omega)

end

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Answer 1

Shubham Khatri 2021-7-5

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https://ww2.mathworks.cn/matlabcentral/answers/870418-i-want-to-solve-this-function-and-get-the-omega-value-but-i-don-t-know-how-to-use-it-please#answer_740108

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Hello,

To my understanding, please use a different variable as an iterator to for loop. I have replaced omega with i. Also, I have created an empty matrix to store the values from fsolve.

In the fsolve fundtion, you need to add variable as a matlab function.

In my understanding, in this case, the solution entirely depends on the initial value (here i). I recommand you to please check the inital condition.

clear all;
clc;
empty=[];
for i=1:100 
syms omega a h g del eps
tb= 3;
lb= 10;                        
wb= 5;                         
E= 205e9;                          
rho= 7850;                                                                              
I=((tb^3)*wb)/12;
pi=3.414;
A=tb*wb;
K=0.833;
G= E/2/(1+0.28);
a=((rho*A*omega^2)/(E*I))^0.25;
h=((1-(rho*I*omega^2)/(K*A*G))*a^4)^0.25;
g=(((a^4*I/A)+rho*omega^2/(K*G)))^0.5;
del=((h^4+(g^4)/4)^0.5+(g^2)/2)^0.5;
eps=((h^4+(g^4)/4)^0.5-(g^2)/2)^0.5;
F1 = ((del)^5*(sin((del)*lb))^2+(del)^2*(eps)^3*sin((del)*lb)*sinh((eps)*lb)-(eps)^2*(del)^3*sin((del)*lb)*sinh((eps)*lb)+(eps)^5*(sinh((eps)*lb))^2)...
              -((del)^5*(cos((del)*lb))^2+(del)^2*(eps)^3*cos((del)*lb)*cosh((eps)*lb)-(eps)^2*(del)^3*cos((del)*lb)*cosh((eps)*lb)+(eps)^5*(cosh((eps)*lb))^2);
empty(i)=fsolve(matlabFunction(F1),i);
end
empty