Chapter 11: Failure of Meatls

Example 11.1 Page 396

#initiation of variable
from math import pi
sigma=40.0*10**6 # in Pa  Tensile stress
E=69.0*10**9  #Modulus of elasticity  in pa
Ys=0.3  #Specific surface energy  in N/m^2


#calculation
a=2*E*Ys/(pi*sigma**2) #Maximum length of surface flaw

print" Maximum length of surface flaw without fracture is %.1f micro meter " %(a*1e6);

 Maximum length of surface flaw without fracture is 8.2 micro meter 

Example 11.3 (Design Problem 11.2) Page 421

#initiation of variable
T=800+273.0;  # Ambient temperature  in K
#stress is 140 MPa
L_M=24.0*10**3 # Larson - miller parameter 
#From Graph of Fig. 8.32 Larson-Miller Parameter is deduced

#calculation
t=10**((L_M/T)-20)
print" Time to rupture for a component is %d hours" %t,"(%.1f days)" %(t/(24.0))
print "Answer in book is 233 hours. it is because of approximation at intermediate stage"

 Time to rupture for a component is 232 hours (9.7 days)
Answer in book is 233 hours. it is because of approximation at intermediate stage