Parametric Study of Pipeline Burst Pressure

Hello, 

I am trying to do a parametric study on how varying a defect in a pipeline wall will affect the burst pressure of said pipeline. I'd like to independantly vary L,d and c below, and apply a variation once in turn and present the change in the burst pressure for that variable. What i've been using is pasted below. This is the code that works and produces an output. What i was doing was to turn L and c into vectors between 0 and 20mm (integers) and d between 0 and 15.9mm in 0.8mm increments.

Was getting various errors, matrix not matching, returning NaN, wrong use of / \ operators etc..... My knowledge of Matlab is limited, admittedly. Any help appreciated

clc, close all, clear all

UTS=530; % Ultimate tensile strength ,MPa

sigma_y=448; % Yield strength, MPa

t=16.8; % thickness, mm

D=558.8; % outer diamter, mm

L=0; % defect length, mm

d=0; % defect depth, mm

c=0; % defect width, mm

sigma_f= 1.1*sigma_y; % effective stress in MPa

n=10; % strain hardening as a %

k=(L^2)/(D*t);

% ASME B31G MODEL

if k>50

M=0.032*k+3.3; % Folias Factor

else

M=sqrt(1+0.6275*k-0.003375*(k^2));

end

Pb_ASME=(2*t*sigma_f/D)*((1-0.85*d/t)/(1-0.85*d/(t*M))) % burst pressure in Mpa

[David Gray]

After spending some more time on this i've used 'for loops' to vary the defect depth but the result is messy..... Is there a better way than this?

% ANALYTICAL MODELS FOR PIPE BURST PRESSURE DUE TO SINGLE CORROSION

clc, close all, clear all

UTS=530; % Ultimate tensile strength ,MPa

sigma_y=448; % Yield strength, MPa

sigma_f= 1.1*sigma_y; % effective stress in MPa

n=10; % strain hardening as a %

t=16.8; % thickness, mm

D=558.8; % outer diamter, mm

L=(0:1:20); % defect length, mm

%d=(0:0.798:15.96); % defect depth, mm

w=0.1; % defect width, mm

% DNV Method

rootDt=sqrt(558.8*16.8);

Q=sqrt(1+(0.31.*(L/rootDt).^2)); % length correction factor

for d=0:0.798:15.96

Pb_DNV=(2*UTS*t/(D-t)).*((1-(d./t))./(1-(d./(t.*Q)))); % burst pressure with DNV Method

end

% Pipeline Corrosion Criterion (PCORRC) Evaluating Method

for d=0:0.798:15.96

Pb_PCORRC=(2*UTS*t/D).*(1-((d./t).*(1-(exp(-0.157*(L./sqrt(279.4.*(t-d))))))));

end