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/mm²

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/mm₂  ( )                               ---------- (i)

If  a/W  =  5/25=1/5  is regarded as small, then

                      -----------(ii)

 (i) and (ii) are only approximately close.