Ski boot walking attachment appendix

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=Logarithmic Decrement Code=
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=Code=
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==Logarithmic Decrement==
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===readenct.m===
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Reads in the text file generated by the MSE Rectilinear apparatus.
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<pre>
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<nowiki>
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function [t,f,val]=readenct(filename,vd,encnum)
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a=textread(filename,'','headerlines',23);
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if strcmp(vd,'d')
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    val=-a(:,encnum+1);
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end
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if strcmp(vd,'v')
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    val=-a(:,encnum+5);
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end
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t=a(:,1);
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f=a(:,2);
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</nowiki>
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</pre>
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===num4.m===
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Using the data returned by readenct, allows determination of physical constants using logarithmic decrament analysis.
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<pre>
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<nowiki>
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[time,force,displacement]=readenct('medium_natural.txt','d',1);
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figure(1)
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plot(time,displacement+0.1198);
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axis([10.6 11.4 -4 4.2])
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a=ginput
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c=max(a)
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figure(2)
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plot(time,displacement+0.1198);
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axis([10.6 11.4 -4 4.2])
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b=ginput
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d=max(b)
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prompt={'Number of Peaks in between','X Coordinate First MAX.','X Coordinate Second MAX.'}
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name='Get User Input';
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numlines=1;
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defaultanswer={'0','0','0'};
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answer=inputdlg(prompt,name,numlines,defaultanswer);
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n=str2double(answer{1});
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x1=str2double(answer{2});
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x2=str2double(answer{3});
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T=(x2-x1)/(n);
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dampingRatio=((1/(n-1))*(log(c(1,2)/d(1,2))))/sqrt((4*pi^2)+((1/(n-1))*(log(c(1,2)/d(1,2))))^2)
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naturalFrequency=((1/(n-1))*log(c(1,2)/d(1,2)))/(dampingRatio*T)
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dampedNaturalFrequency=naturalFrequency*sqrt(1-dampingRatio^2)
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m=0.79;
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k=naturalFrequency^2*m
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CoefficientOfDamping=dampingRatio*2*sqrt(k*m)
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</nowiki>
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</pre>

Revision as of 20:55, 9 December 2008

Contents

Code

Logarithmic Decrement

readenct.m

Reads in the text file generated by the MSE Rectilinear apparatus. 


function [t,f,val]=readenct(filename,vd,encnum)

a=textread(filename,'','headerlines',23);
if strcmp(vd,'d') 
    val=-a(:,encnum+1);
end
if strcmp(vd,'v') 
    val=-a(:,encnum+5);
end
t=a(:,1);
f=a(:,2);

num4.m

Using the data returned by readenct, allows determination of physical constants using logarithmic decrament analysis. 


[time,force,displacement]=readenct('medium_natural.txt','d',1);
figure(1)
plot(time,displacement+0.1198);
axis([10.6 11.4 -4 4.2])


a=ginput
c=max(a)

figure(2)
plot(time,displacement+0.1198);
axis([10.6 11.4 -4 4.2])


b=ginput
d=max(b)

prompt={'Number of Peaks in between','X Coordinate First MAX.','X Coordinate Second MAX.'}
name='Get User Input';
numlines=1;
defaultanswer={'0','0','0'};
answer=inputdlg(prompt,name,numlines,defaultanswer);
n=str2double(answer{1});
x1=str2double(answer{2});
x2=str2double(answer{3});

T=(x2-x1)/(n);
dampingRatio=((1/(n-1))*(log(c(1,2)/d(1,2))))/sqrt((4*pi^2)+((1/(n-1))*(log(c(1,2)/d(1,2))))^2)
naturalFrequency=((1/(n-1))*log(c(1,2)/d(1,2)))/(dampingRatio*T)
dampedNaturalFrequency=naturalFrequency*sqrt(1-dampingRatio^2)
m=0.79;
k=naturalFrequency^2*m
CoefficientOfDamping=dampingRatio*2*sqrt(k*m)
Retrieved from "https://wiki.ece.cmu.edu/ddl/index.php/Ski_boot_walking_attachment_appendix"
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