Code covered by the BSD License

# Rotor Dynamics toolbox (RotFE)

### Izhak Bucher (view profile)

Toolbox models rotating, elastic shafts with disks

[U,Wv]=rotunbal(Rot,W,N)
```function [U,Wv]=rotunbal(Rot,W,N)
%[U,Wv]=rotunbal(Rot,W,N)
%
%  Compute the response to unbalance at a range of speeds
%
% The co-ordinates for which Rot.RESP_DOF
%        (see Rot.RNodeDir in themodel file) is selected
% The unbalance is defined in Rot.UNBALANCE
%
% Input:
%  Rot:  a model file or a Rot structure
%  W  : optional, speed range in RPM W=Wmax, W=[W1 W2]
%  N:   number of speeds between 0-Wm or W1-W2
%
% By:
%  I.Bucher 24-10-98

if isstr(Rot), Rot=rotfe(Rot); end  % template to Rot

nM=size(Rot.M,1); z=sparse(nM,nM);

nr=length(  Rot.RESP_DOF );

% construct Speed vector
if nargin<3, N=100; end
if nargin<2, W=10000; end

if length(W)>1, W1=W(1)*2*pi/60; W2=W(2)*2*pi/60;
else, W1=0; W2=W(1)*2*pi/60; end
Wv=linspace(W1,W2,N);
U=zeros(N, nr);
for q=1:N,
w=Wv(q);
a= ( -w^2*Rot.M+i*w*(w*Rot.G+Rot.D)+Rot.K);
b=w^2*(Rot.Fu_cos-i*Rot.Fu_sin);
if isfield(Rot,'Reduct')
if Rot.Reduct.flag, c=Rot.T*(a\b); else, c=a\b;end
else, c=a\b;
end
U(q,:)=c( Rot.RESP_DOF ).';
end

```