The parameter K in Equations 9.7a, 9.7b, and 9.7c is a function of the applied nominal stress (sigma) and crack length (a) as K=sigma(sqrt(pi*a).
Compute the magnitudes of the normal stresses (sigma,x) and (sigma,y) in front of a surface crack of length 2.0 mm in response to a nominal tensile stress of 100 MPa at the following positions:
a) r= 0.1mm, theta= 0?
b) r= 0.1mm, theta= 45?
c) r= 0.5mm, theta= 0?
d) r= 0.5mm, theta= 45?