Data Analysis of Tesile Test Data

Force and Displacement data obtained from tension test of a dual-phase advanced high strength steel
was analyzed to obtain mechanical properties of the material.

Software Used: MATLAB

Dimensions of the specimen:
Width≔6.5 mm
Thickness≔1.38 mm
Ao = Original_Area≔Width⋅Thickness=8.97 mm2
lo = Original Gage Length =25.46 mm

Following formulas were used to obtain necessary properties/plots:

MATLAB code was generated to analyze a data containing 600 data points and required graph was plotted as shown below:

Results are as follows:

Elastic Modulus, E = 135.33 GPa
0.2% offset yield strength = 731.7 MPa
Resilience = 3.56 N.mm/mm2
Ultimate Tensile Strength = 979.3 MPa
Elongation = 17.59%
Toughness = 158.87 N.mm/mm2
Elastic Strain recovered = 0.007 mm/mm
Plastic Strain remaining = 0.033 mm/mm
New Gage Length = 26.30 mm

MATLAB Code:

%MSEN 625 Project 1
w=6.5; %Initial Width, mm
t=1.38; %Initial Thickness, mm
lo=25.46; %Initial gage length, mm
Ao=w*t; %Initial Area, mm

Data = [
0.000   0.000
494.297 0.004
632.523 0.004
737.398 0.001
833.917 0.001
924.378 0.007 ...
...7104.432   4.345
7046.074   4.359
6983.672   4.372
6917.775   4.387
373.945 4.479];

Engg_SS = [Data(:,1)/Ao Data(:,2)/lo]; %Data for Engineering Stress Strain Curve.

plot(Engg_SS(1:599,2),Engg_SS(1:599,1)); %Plotting engineering SS curve
hold on;

%Calculating True Stress Strain Values:
True_SS(505,2)=0;
for i=1:505
True_SS(i,1) = (Engg_SS(i,1)*(1+Engg_SS(i,2)));
True_SS(i,2) = log(1+Engg_SS(i,2));
i=i+1;
end
plot(True_SS(:,2),True_SS(:,1));%Plotting True SS Curve
hold on;

%Calculating Material Properties:
%Selecting Two Points in the elastic region of the curve
x1=0.0002749;
y1 = 103.1;
x2 = 0.003255;
y2 = 506.4;

E=(y2-y1)/(x2-x1); %Young's Modulus

%Plotting line for Young's Modulus
x=0.002:0.000001:0.009;
y=E*(x-0.002);
hold on;
plot(x,y,'r');
hold on;
YS = 731.7; %Yield Strength, MPa

for j=1:600
if(Engg_SS(j,1) <= 731.7)
Res(j,1)=Engg_SS(j,1);
Res(j,2)=Engg_SS(j,2);
else
break
end
end
%plot(Res(:,2),Res(:,1),'c'); PLOT TO CHECK RESILIANCE AREA
%hold off;

Resilience=trapz(Res(:,2),Res(:,1));
UTS=max(Engg_SS(:,1));
Toughness=trapz(Engg_SS(1:599,2),Engg_SS(1:599,1));
Elongation=max(Engg_SS(:,2));

%Unloading curve
hold on;
%xu=[0.04 0.04];
%yu=[0 1000];
%plot(xu,yu);

yun2=951.4;
xun2=0.04;
xun1=(E*xun2-951.4)/E;
plot([xun1 xun2],[0 yun2]);
Elastic_Recovery=0.04-xun1;
Plastic_strain=xun1;

%Print all Values:
E
YS
UTS
Elongation
Resilience
Toughness
Elastic_Recovery
Plastic_strain
New_Gage_Length = lo*(1+xun1)
hold off;

Data Analysis of Tensile Test Data