Contents

Universal File Modal Demo

This demo shows how to import modal analysis data and a geometry from a universal file. In this script data are imported, then curve fitted. A predefined geometry is imported for animation of the modes, and finally an AVI file is generated of the animation of the first mode.

% Comments:
% The curve fitting is done with COMPLEXP, which is NOT a polyreference implementation.
% However, you can still use several references to obtain the poles. The data come from
% a 2-input shaker test on a small plastic airplane model. In this demo we use both
% references.

% Copyright (c) 2003-2006, Axiom EduTech AB, Ljusterö, Sweden. All rights reserved.
% URL: http://www.vibratools.com Email: info@vibratools.com

Ref=[1:2];

UnvDataName='ModelPlaneFRF.unv';
UnvGeoName='ModelPlaneGeo.unv';

Import Universal Data File

lo=100;                        % File names will start with uf100
nseq=univread(100,UnvDataName);
hi=nseq-1;

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List the Contents of First 20 Files

%There are some useful commands to list the contents of the imported
% universal file, for example:
funclist([100:119],'ref','uf');

File no  Response  Reference   Func Type
    101       1Z+        7Z+         FRF
    102       2Z+        7Z+         FRF
    103       3Z+        7Z+         FRF
    104      28Z-        7Z+         FRF
    105      20Z+        7Z+         FRF
    106      30Z+        7Z+         FRF
    107       4Z+        7Z+         FRF
    108       5Z+        7Z+         FRF
    109       7Z-        7Z+         FRF
    110       9Z+        7Z+         FRF
    111       8Z+        7Z+         FRF
    112       6Z+        7Z+         FRF
    113      21Z+        7Z+         FRF
    114      22Z+        7Z+         FRF
    115      23Z+        7Z+         FRF
    116      26Z+        7Z+         FRF
    117      25Z+        7Z+         FRF
    118      24Z+        7Z+         FRF
    119      33Z+        7Z+         FRF
    100      56Z+       28Z+         FRF

Read All FRFs Into a Single FRF matrix

This will create a matrix, H, NoFreqs-By-NoResponses-By-NoForces and some vectors with DOFs and directions.

[H,f,ForceNo,ForceDir,RespNo,RespDir]=uf2frf(lo,hi,'no');

Warning: Duplicate FRF found for Response: 56Z+ and Force: 28Z+. Discarded.

Find and Plot Driving Point FRF of First Reference

idx=find(RespNo == ForceNo(Ref(1)));
figure
semilogy(f,abs(H(:,idx,1)))
xlabel('Frequency, Hz')
ylabel('Mobility, (m/s)/N')

Select Frequency Range for Curve Fitting

figtext(10,5,'Select Frequency range (low/high)')
[ff,dd]=ginput(2);
flo=ff(1); fhi=ff(2);
fprintf('Frequency range %6.1f to %6.1f Hz selected.\n',ff)

Frequency range   25.9 to  103.3 Hz selected.

Truncate H and Convert to Mobility

All ModalTools curve fitting is done on mobility data

[Ht,ft]=frftrunc(H(:,:,Ref),f,flo,fhi);
Hv=cvfrfa2v(Ht,ft);

Calculate Impulse Responses of All FRFs in H

[h,t,fs] = impresp(Hv,ft);

Calculate Multivariate Mode Indicator Function

MIF = muvamif(Hv);

Curvefit for Poles

poles = complexp(h,fs,min(200,length(ft)),40,MIF,ft);
[fr,zr]=poles2fd(poles);
fprintf('Resonance frequencies and damping ratios:\n')
fprintf('%16s%16s\n','Undamped Freq.','Rel. Damping')
fprintf('%11s%15s\n','Hz','%')
fprintf('%12.2f%16.3f\n',[fr zr].')
fprintf('\nPress any key to continue...\n')
%

Resonance frequencies and damping ratios:
  Undamped Freq.    Rel. Damping
         Hz              %
       28.35           1.223
       40.23           1.223
       75.08           0.709
       83.79           0.742
       91.38           1.066
       94.22           0.666
       97.67           0.861
       99.61           0.794

Press any key to continue...

Curve Fit for Residues

DispTime=0;          % Suppress plotting
[residues,residuals] = pol2resf(H(:,:,1),f,poles,5,120,DispTime);

Import Geometry

geo=univr15(UnvGeoName);
plotseq=univr82(UnvGeoName);
% UF2FRF sorts response dofs in ascending order.
% So we need to sort geo in the same order.
[dum,I]=sort(geo(:,1));
% Sort geo so first column is in ascending order
geo=geo(I,:);
[geonew,psnew,list] = geocond(geo,plotseq);
% Check that "list" is equal to RespNo from the universal file FRFs
if min((list == RespNo')) == 1
    [M,N]=size(geonew);
    [MM,NN,RR]=size(residues);
    geoadd=[zeros(M,2) sign(RespDir').*[1:46]'];
else
    error('Imported geometry and FRF are not consistent.')
end
geonew=[geonew geoadd];

Reading UF Type 15 Data block
Reading UF Type 82 Data block
Reading UF Type 82 Data block
Reading UF Type 82 Data block
Reading UF Type 82 Data block
Reading UF Type 82 Data block
Reading UF Type 82 Data block

Set Up Animation

N = length(poles);
for n = 1:N
    sn = int2str(n);
    eval(['[gpoint,G',sn,',ref] = animcalc(geonew,psnew,residues(',sn,',:),.1,0);'])
end
x = 10*ones(1,N);
y = linspace(10,90,N);
y = fliplr(y);
txt=sprintf('%4s%7.1f%3s','#1:',fr(1),' Hz');
for n = 2:N
    S=sprintf('%4s%7.1f%3s',['#' int2str(n) ':'],fr(n),' Hz');
    txt = str2mat(txt,S);
end
%
call = str2mat('animatebutt(1,gpoint,G1,ref,5,x,y,txt,call)');
for n = 2:N
    eval(['st = ''animatebutt(1,gpoint,G',int2str(n),',ref,5,x,y,txt,call)'';']);
    call = str2mat(call,st);
end
animatebutt(1,gpoint,G1,ref,5,x,y,txt,call);
figtext(100,160,'Animate modes as you please. When done, continue by pressing');
fprintf(' <RETURN> when the Again button shows');
pause

 <RETURN> when the Again button shows

Save the Third Mode Shape as an AVI File

mno = 3;            % Mode number: change for another mode!
[gpoint,G,gref]=animcalc(geonew,psnew,residues(mno,:),.05,0);
FileName=strcat('Mode',num2str(fr(mno)),'Hz.avi');
close all
avimode(FileName,gpoint,G,0,8,[-135,-360-135],[17,17]);


				
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Published with MATLAB® 7.1