tdof_ss_time_ode45_slnk.m

vibration simulation using ansys and matlab 一书中的程序

	echo off
%	tdof_ss_time_ode45_slnk.m	state-space solution of tdof model with
%	initial conditions, step function forcing function and displacement
%	outputs	using the ode45 solver or Simulink, user is prompted for
%	damping values.
%	Solves for time domain response of tdof problem using Matlab's
%	ODE45 solver, a Runga-Kutta method of solving differential equations, 
%	and also using Matlab's Simulink block-diagram simulation tool.  

	clear all;

	global a b u			%	this is required to have the parameters available
							%	for the function

	which_run = input('enter "1" for Simulink or "enter" for ode45 run ...  ');

	if  isempty(which_run)
		which_run = 0
	end

%	define the values of masses, springs, dampers and Forces

	m1 = 1;
	m2 = 1;
	m3 = 1;

	c1 = input('input value for c1, default 0.0, ...  ');
	
	if  (isempty(c1))
		c1 = 0.0;
	else
	end

	c2 = input('input value for c2, default 0.0, ...  ');
	
	if  (isempty(c2))
		c2 = 0.0;
	else
	end
	
   	k1 = 1;
	k2 = 1;

	F1 = 1;
	F2 = 0;
	F3 = -2;

%	define the system matrix, a

	a = [  0      1         0			 0		   0	  0
		-k1/m1 -c1/m1     k1/m1        c1/m1       0	  0	
		   0      0         0            1         0      0
		 k1/m2  c1/m2  -(k1+k2)/m2  -(c1+c2)/m2  k2/m2  c2/m2
		   0      0         0            0         0      1
		   0      0       k2/m3        c2/m3    -k2/m3 -c2/m3];

%	define the input matrix, b

	b = [  0
		 F1/m1
		   0
		 F2/m2
		   0
		 F3/m3];

%	define the output matrix for transient response, c, displacements only

	c = [1 0 0 0 0 0
	     0 0 1 0 0 0
		 0 0 0 0 1 0];

%	define the direct transmission matrix for transient response, d, the same number of rows as c and
%	the same number of columns as b

	d = zeros(3,1);

	if  which_run == 0		%	transient response using the ode45 command		

	u = 1;

	ttotal = input('Input total time for Simulation, default = 10 sec, ...  ');

   	if (isempty(ttotal))
     	ttotal = 10;
	else
   	end

	tspan = [0 ttotal];

	x0 = [0 -1 -1 2 1 -2]';		%  initial condition vector, note transpose

	options = [];			%  no options specified for ode45 command

  	[t,x] = ode45('tdofssfun',tspan,x0,options);

	y = c*x';				% note transpose, x is calculated as a column vector in time

	plot(t,y(1,:),'k+-',t,y(2,:),'kx-',t,y(3,:),'k-')
	title('State-Space Displacements of dof 1, 2 and 3')
	xlabel('Time, sec')
	ylabel('Vibration Displacements')
	legend('dof 1','dof 2','dof 3')
	grid

	else		%  setup Simulink run

%	define the direct transmission matrix for transient response, d, the same number of rows as c and
%	the same number of columns as b

%	define time for simulink model

	ttotal = input('Input total time for Simulation, default = 10 sec, ...  ');

   	if (isempty(ttotal))
     	ttotal = 10;
	else
   	end

	disp('  ');
	disp('  ');
	disp('  ');
	disp('  ');
	disp('  ');
	disp('  ');
	disp('Run the Simulink model "tdof_ss_simulink.mdl" and then');
	disp('run the plotting file "tdof_ss_time_slnk_plot.m"');
	
	end