I have some coupled nonlinear ordinary differential equations. Three equations have three 2nd order derivative coupled together. Can someone tell me how I can get the response
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prabin kumar meher
le 21 Sep 2022
Commenté : prabin kumar meher
le 22 Sep 2022
I have some coupled nonlinear ordinary differential equations. Three equations have three 2nd order derivative coupled together. Can someone tell me how I can get the response, numerically? i.e t vs x , t vs theta dot plots.
Thanks in advance
2 commentaires
James Tursa
le 21 Sep 2022
Do you have initial conditions for all the variables and first derivatives?
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James Tursa
le 21 Sep 2022
Modifié(e) : James Tursa
le 21 Sep 2022
Another related approach is to isolate all the 2nd derivatives on the LHS and put everything else on the RHS. Then pick off the coefficients of the 2nd order derivatives to form a matrix problem that you solve for the 2nd derivatives. E.g., the matrix problem would look something like this based on your comment edits:
A*z = b
where
A = [ 1 0 -f*sin(theta);
0 1 f*sin(theta);
-m*e*sin(theta) m*e*cos(theta) (m*e^2+Ip)/B^2]
and
z = [x_dotdot; y_dotdot; theta_dotdot]
and
b = 3x1 vector with all the other stuff from RHS
Then solve for z to get the 2nd derivatives.
7 commentaires
Torsten
le 22 Sep 2022
Modifié(e) : Torsten
le 22 Sep 2022
It works up to t = 90 approximately (see above).
Then all your variables seem to blow up.
Either your equations are wrong, there is a singularity around t = 90 or the integrator is not able to solve your problem.
For all three problems, I cannot be of help.
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