How can I find the point of intersection between a set of data and a line?

I am currently analyzing a stress strain curve and using the offset method to determine the yield strength. I can't seem to find a reliable method to find the intersection between the data set and the offset line.

Answer 1

[Star Strider]

I have no idea what you’re actually doing, since I don’t have your data or the line you want to compare it with. (Details are always helpful. My background is not in materials science.)

My guess is that the interp1 function would be worth considering, if your data are compatible with it.

[Ethan Echols]

Here is my code. Basically, I am trying to find the coordinates of the intersection of two data sets which share the same independent variable.

% Part a

A=csvread('LoadExtension.csv',2,0);

% Part b

E=A(:,1)*10^-3; % Extension in meters F=A(:,2); % Applied load in Newtons A=0.0015*0.0061; % Cross-sectional area in meters^2 L=0.05; % Initial length in meters STRESS=F/A; STRAIN=E/L; plot(STRAIN,STRESS); title('Stress-Strain Curve'); xlabel('Strain'); ylabel('Stress (Pa)');

% Part ci

index=(STRAIN>=0.01)&(STRAIN<=0.05); YM=polyfit(STRAIN(index),STRESS(index),1) % Elastic modulus in Pascals

% Part cii

US=max(STRESS) % Ultimate strength in Pascals

% Part ciii

O=(1.430049016757187*10^8)*(STRAIN-0.002)+0.011478042564688; % Offset line

[Star Strider]

I don’t have your data and you didn’t format your code, so I’m just a tad further than I was.

I now know is that ‘O’ is a linear function of ‘STRAIN’.

[Ethan Echols]

'O' is a linear function of 'STRAIN,' and 'STRESS' is an array of numerical data with dependence on 'STRAIN.' I am trying to find the point of intersection between the graphs of 'STRESS' and 'O', both of which share 'STRAIN' as the x-axis.

[Star Strider]

That I understand. However, I have no idea what the ‘STRESS’ curve as a function of ‘STRAIN’ looks like. Without the data, I can’t provide even an approximate solution.