Calculate stress intensity factor:
For the plate in Figure (a) W = 25 mm, 2a = 10 mm, plate thickness, t = 2 mm, Load P = 1000 N. Calculate stress intensity factor if length of plate is 150 mm.
Solution
For crack at a distance of 75 mm from loaded end, the effect of edge on SIF may be disregarded.
SIF may be calculated from Eq. (3).
s = P/ Wt = 1000 /25 ´2 = 20 N/mm^{2}
P a / W = P´5/25 = 0.6284
∴ tan P a /W = tan 0.6284= 0.7265 (Note P a/W is in radians)
∴ K_{ I} = s[W tan P a / W]^{1/2} = 20[25´0.7256]^{1/2}
or, K I = 85.235 N/mm_{2} ( ) ---------- (i)
If a/W = 5/25=1/5 is regarded as small, then
-----------(ii)
(i) and (ii) are only approximately close.