CIFER®-MATLAB Interfaces: Development and ... - Cal Poly

Appendix H: Mass-Spring-Damper Case Example
This example is for a simple second order mass-spring-damper system modeled in Simulink as a
transfer function. A frequency sweep simulating noise was run through the model and the input
and output data recorded into a time history file. One case was set up entirely in CIFER and then
a second was set up and run from MATLAB. The commands shown below were used to run the
case from MATLAB. Calls to the CIFER-MATLAB interface functions have been highlighted in
red. This example is provided to give a very simple scenario to set up cases using the MATLAB
interface. CIFER does not come with this example so the simulation would have to be created and
run in order to generate the data necessary.
% Assign a blank frespid structure
f_in = frespid;
thename = 'MASSSPRG';
% Fill in all the necessary information to make the case
f_in.casename
= thename;
f_in.comments
f_in.caseout
= 'mass spring system';
= thename;
f_in.crosscor
= 'Y';
% Time history selection parameters:
f_in.source = 5;
f_in.evntnum(1) = 1;
f_in.flghtnum(1)
f_in.thdt
= 1;
= 0.01;
f_in.thfile(1)
= {'massspring.CIFERTEXT'};
% channel definition parameters:
f_in.controls(1)
= {'IN'};
f_in.outputs(1)
= {'OUT'};
f_in.conchnl(1,1)
f_in.outchnl(1,1)
= {'IN'};
= {'OUT'};
% Frequency response selection parameters
f_in.frcalc(1,1) = {'*'};
% NOTE: The file 'massspring.CIFERTEXT' was created for this example,
% in order to run the example this file must be created.
% Save the structure into the database
frespid(f_in,2);
% Change the window sizes and turn them on.
frespid('MASSSPRG',2,'winlen',[30,25,20,15,10],'winon',{'*','*','*','*',
'*'},
'maxfft',[125,125,125,125,125]);
% Set up blank composite case
c_in = composite;
% Fill in appropriate values
c_in.casename
= thename;
c_in.comments
c_in.casein
= 'mass spring system';
= thename;
c_in.caseout
= thename;
c_in.inpgm
c_in.controls(1)
= 'FRE';
= {'IN'};
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