How to calculate the intersection point of lines on a loglog graph.

I have the following code, and it outputs linear lines on a loglog graph, I've been trying to find a way to plot the xvalue of the intercept point of the elastic and plastic strain lines that are outputted, thanks for any help!

Answer 1

[Torsten]

eprime=0.59;
sigmaprime=277500;

%Constants for Manson Coffin Equation
b=-0.087;
c=-0.58;

%Young's Modulus
E=30*10^6;

%Creating equations to be plotted
%N is the number of reversals
N=logspace(1,6);

%Strain Equations
ElasticStrain=(sigmaprime/E)*(2*N).^b;
PlasticStrain=eprime*(2*N).^c;

idx = find(abs(ElasticStrain-PlasticStrain)==min(abs(ElasticStrain-PlasticStrain)));
xvalue= N(idx);
yvalue=ElasticStrain(idx);

TotalStrain=PlasticStrain+ElasticStrain;

%Generating a Log-Log graph, with all three strain equations.
loglog(N,ElasticStrain,N,PlasticStrain,N,TotalStrain,xvalue,yvalue,'*')
legend({'Elastic Strain','Plastic Strain','Total Strain'},'Location','northeast','Orientation','vertical')
title('Predicting Cycle Failure with Strain Life Analysis')
xlabel('Reversals to Failure,2N')
ylabel('Strain Amplitude')

%Calculating the Strain amplitude at 50000 Cycles
N=50000;
StrainAmplitude=eprime*(2*N).^c+(sigmaprime/E)*(2*N).^b

StrainAmplitude = 0.0041

[Michael Lawlor]

You rock! Thanks for the help!