Creep and Fatigue: Secondary Creep Rate and Tensile Tests

FACULTY OF TECHNOLOGY
COURSE WORK SPECIFICATION 2018/2019
ADVANCED SOLID MECHANICS
ENGT5258/ENGD5258
CREEP & FATIGUE
ASSIGNMENT
2018
Institutional Affiliation
Student Name

CREEP & FATIGUE
Question 2
%%Secondary creep rate obtained from creep tests-Aluminum alloy at 100Deg
Centigrade
Scr=[6.2e-6 4.2e-5 1.42e-4 2.3e-4 4.7e-4 6.2e-4]; %secondary creep rate
stress=[120 160 210 250 280 300]; % Stress
p = polyfit(Scr,stress,2);
% Evaluate the fitted polynomial p and plot:
f = polyval(p,Scr);
figure(1)
plot(Scr,stress,'o',Scr,f,'-')
legend('Aluminium Alloy','linear fit')
title('Norton Power Law for Creep')
xlabel('Stress')
ylabel('Secondary creep rate')
grid on
The output is obtained as,
0 1 2 3 4 5 6 7
Stress 10-4
120
140
160
180
200
220
240
260
280
300
Secondary creep rate
Norton Power Law for Creep
Aluminium Alloy
linear fit
Question 3
1

CREEP & FATIGUE
%%Secondary creep rates for a series of tensile tests as various temperatures
under the same load
T=[290 300 310 320 330];
str1=[4.8e-6 2.74e-5 1.4e-4 6.44e-4 2.7e-3];
p1=polyfit(T,str1,2);
%to determine the coefficients of the function formed
f1=polyval(p1,T);
figure(2)
plot(T,str1,'*',T,f1,'-')
legend('Arrhenius Material','Quadratic Fit')
title('Tensile Tests over various Temperatures')
xlabel('Temp(Deg.C)')
ylabel('Secondary creep rate')
grid on
The output is obtained as,
290 295 300 305 310 315 320 325 330
Temp(Deg.C)
-0.5
0
0.5
1
1.5
2
2.5
3
Secondary creep rate
10-3 Tensile Tests over various Temperatures
Arrhenius Material
Quadratic Fit
Question 4
2