Abstract: The interaction of cracks in a doubly periodic arrey with one collinear directionis analysed and a new approximate method of solving the problem is developed based onthe segragation analysis and superposition principle. The stress intensity factors of cracktips and the displacement jump across the crack surface are expressed by analytic or semi-analytic form. The effective moduli and the compliance matrix of the cracked plate are alsoformulated.The method is effective with its simple procedure and high accu...