Problem with graph MATLAB

I am trying to plot a creep x time graph using matlab. However, there are some mismatches between my graph and the reference paper.

This is my code:

% Parameters

c1= 6.48; %MPa
c2= 5.17; %GPa.d
a1= 1.29e-7; %MPa^-5.d^-1
a2= 1.6e-11; %MPa^-5.d^-1
b=66.28;
n=5;
r=2.6;
G=26.9; %GPa
u=0.4;
t(1)=0;
et(1)=0;
es(1)=0;
ed(1)=0;
etotal(1)=0;
sigma1=26; %MPa
sigma2=1; %MPa
sigma3=1; %MPa

% Loop

for i=1:355

t(i+1)=t(i)+0.01;

%Calculation

sigma= sigma1-sigma3;
sigmam=(sigma1+sigma2+sigma3)/3;

sigmadamage=sigma*((2/3)*(1+u+3*(1-2*u)*((sigmam/sigma)^2)))^0.5

% Damage Factor

D(i+1)= 1-(1-(r+1)*((sigmadamage/b)^r)*t(i+1))^(1/(r+1));

% Creep

%Primary Creep

et(i+1)=(sigma/c1)*(1-exp(-G*t(i+1)/c2));

%Secondary Creep

es(i+1)=a1*(sigma^n)*t(i+1);

%Tertiary Creep

ed(i+1)=a2*((sigma/(1-D(i+1)))^n)*t(i+1);

%Total Creep

etotal(i+1)= et(i+1)+es(i+1)+ed(i+1);

end

p = plot(t,etotal,'-b');
p(1).LineWidth = 1.5;
title('Creep x Time')
xlabel('Time(day)')
ylabel('Creep (%)')
grid on
legend([p(1)], 'Creep Evolution')

I really cannot see which type of error in my code is provoking this mismatch.

Thanks

Additional data:

Answer 1

[Abraham Boayue]

Your code seems to be right, but the for loop is really not suitable in this case. However, there is a slight variation in the result when the for loop is omitted. You might want to check your parameters to be sure that they are entered correctly, for instance, I see that you entered both units of GPa and MPa in the same way. I think you should enter all pressure as either GPa or MPa to be consistent. Here the code without the for loop.

clear variables
close all
% Parameters
c1 = 6.48;    %MPa
c2 = 5.17;    %GPa.d
A1 = (1.29e-7); %MPa^-5.d^-1
A2 = (1.6e-11); %MPa^-5.d^-1
B = 66.280;
n = 5;
r = 2.6;
G = 26.9; %GPa
mue = 0.4;

sigma1 = 26; %MPa
sigma2 = 1; %MPa
sigma3 = 1; %MPa
sig_hat = sigma1-sigma3;
sigm =  (sigma1+sigma2+sigma3)/3;
a1 = 1+ mue;
a2 = 3*(1-2*mue);
a3 =(sigm/sig_hat)^2;
sigmastar = sig_hat*sqrt(2/3*(a1+a2*a3));

tf = 4;
N = 355;
t = 0:tf/(N-1):tf;

b1 = (1+r);
b2 = (sigmastar/B)^r;
D = 1-((1-b1*b2*t)).^(1/b1);

et = (sig_hat/c1)*(1-exp(-G*t/c2));
es =  A1*(sig_hat^n)*t;
ed = (A2*(sig_hat./(1-D)).^n).*t;
%Total Creep
ec = et+es+ed;

p = plot(t,real(ec),'-b');
hold on
p(1).LineWidth = 1.5;
title('Creep x Time')
xlabel('Time(day)')
ylabel('Creep (%)')
grid on
% ylim([0 15])

%%Your code without the for loop
% c1= 6.48; %MPa
% c2= 5.17; %GPa.d
% a1= 1.29e-7; %MPa^-5.d^-1
% a2= 1.6e-11; %MPa^-5.d^-1
% b=66.28;
% n=5;
% r=2.6;
% G=26.9; %GPa
% u=0.4;
% 
% sigma1=26; %MPa
% sigma2=1; %MPa
% sigma3=1; %MPa
% % Loop
% N = 350;
% t = 0:4/N:4;
% 
% %Calculation
% sigma= sigma1-sigma3;
% sigmam=(sigma1+sigma2+sigma3)/3;
% sigmadamage=sigma*((2/3)*(1+u+3*(1-2*u)*((sigmam/sigma)^2)))^0.5;
% % Damage Factor
% D= 1-(1-(r+1)*((sigmadamage/b)^r)*t).^(1/(r+1));
% % Creep
% %Primary Creep
% et=(sigma/c1)*(1-exp(-G*t/c2));
% %Secondary Creep
% es= a1*(sigma^n)*t;
% %Tertiary Creep
% ed=a2*((sigma./(1-D)).^n).*t;
% %Total Creep
% etotal= et+es+ed;
% 
% p = plot(t,real(etotal),'-b');
% p(1).LineWidth = 1.5;
% title('Creep x Time')
% xlabel('Time(day)')
% ylabel('Creep (%)')
% grid on
% legend([p(1)], 'Creep Evolution')
% % legend([p(1)], 'Creep Evolution')

[Williams Dias]

Thank you for your answer, Abraham!

I am starting to use MATLAB and these suggestions ir order to improve my code are really valuable.

Answer 2

[Sylvester Appu]

The number of combinations Cn,r of taking r objects out of n objects is given by:

Cn,r=n!r!(n−r)!Cn,r=n!r!(n−r)!

In the Powerball lottery game the player chooses five numbers from 1 through 59, and then the Powerball number from 1 through 35.

Determine how many combinations are possible by calculating C59,5 C35,1. (Use the built-in function factorial.)

[Steven Lord]

This isn't related to the original question. Please start a separate message for this new question. [When you do, since this sounds like it's a homework question, please show what you've tried so far to solve this problem and ask a specific question and you may receive some guidance.]

[anil simsek]

I have Arduino code, I want to draw it instantly in matlab. Can you help me ?

Answer 3

[anil simsek]

I have Arduino code, I want to draw it instantly in matlab. Can you help me ?