Forced vibration response Ode45

2014 4 24
1 个回答
更新时间：2021 9 23
6 次查看（30 天）

0 个投票

I am suck on a question for an assignment. I can not get matlab to work the following function I keep getting error messages.
function f=t
F=940*sin(10*pi*t);
k=50000;
damping=0.05;
r=3.224;
x(1+t)=(F/k)/sqrt((1-R^2)^2+4*(damping^2)*r^2);
t=1/(10*pi);
[x,t]=ode45('f',[T,T*50],0);
plot(x)

4 个评论
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A Jenkins
A Jenkins 2014-4-24
编辑：A Jenkins 2014-4-25
Yes, you need some more practice at MATLAB. Type
doc ode45
to see some example problems to work though that will help you learn how it works.
(Some hints for this code...
  • MATLAB cares what order you write things, and how you declare functions.
  • It is also case sensitive, so that 'r' and 'R' are not the same thing.
  • A function handle should be written @f.)
Ryan
Ryan 2014-4-24
Thanks for the reply. I have read the helper page however it doesn't help me figure out where the error is as I have defined things as it states it should be done.
A Jenkins
A Jenkins 2014-4-25
编辑：A Jenkins 2014-4-25
Perhaps you should start with an example that works and slowly make modifications to it until you get to your final result?
Then you will know exactly what change you made and therefore only one line will be incorrect at a time.
(We try not to do people's homework for them, so we only answer specific questions here.)
Ryan
Ryan 2014-4-26
I didn't ask for you to do it for me as you don't have the assignment question. I asked for help with the code I wrote. I have figured out how to do the problem any way.
function [du]=QuestionE(t,u);
du=zeros(2,1);
Damping=0.05;
wn=9.74;
du(1)=-2*Damping*wn*u(1)-u(2)*(wn^2)+(940/530)*sin(10*pi*t);
du(2)=u(1);
end
Damping=0.05;
wn=9.75;
omega=10*pi;
k=50000
m=527.1;
g=9.81;
r=omega/wn;
F=940
wd=wn.*sqrt(1-Damping.^2);
timespan=(50*2*pi)/omega
xst=-(m*g)/k;
v0=0;
A=xst;
B=(v0+Damping*wn*xst)/wd;
[t,u]=ode45(@QuestionE1,[0 timespan],[v0,xst]);
u=exp(-Damping.*wn.*t).*(A.*cos(wd.*t)+B.*sin(wd.*t));
y=(2*Damping*r)/(1-r^2);
fi=atan(y);
X=((F/k)/(sqrt((1-(r^2))^2+4*(Damping^2)*(r^2))))
u1=X.*cos(omega.*t-fi)+u;
plot(t,u,'k')
hold on
plot(t,u1,'b')
title('Forced Vibration Responce')
xlabel('Time')
ylabel('x(t)')

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回答（1 个）

Mohammed Siraj
Mohammed Siraj 2021-9-23

0 个投票

Write the program for the task given: The motion of the forced vibratory system with spring-
mass system is modeled by the following equation, solve the differential equation and find the
displacement, velocity with respect to time (from 0 to 120 seconds).Analyze the system by
MATLAB Programming and validate the solution by using SIMULINK. Assume m=1 kg, k=2
N/m, F=120N and ω=1 rad/sec.

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提问:

Ryan
Ryan
2014-4-24

回答：

Mohammed Siraj
Mohammed Siraj
2021-9-23

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