(Solved): Consider an infinite periodic array of equally spaced cracks along the x-axis with each crack subje ...

Consider an infinite periodic array of equally spaced cracks along the $x$-axis with each crack subjected to a pair of concentrated forces at the center of the crack (Figure I). Verify that the Westergaard function is $Z_1=\frac{P\sin (?a/W)}{W(\sin (?z/W){)}^2}{\left[1?{\left(\frac{\sin (?a/W)}{\sin (?z/W)}\right)}^2\right]}^{?1/2}$ Prove that the stress intensity factor for any crack is given by, $K_l=\frac{P}{{\left(\frac{W}{2}\sin \left(\frac{?a}{W}\right)\right)}^{1/2}}$