International Journal of Fracture 59: R53-R57, 1993. © 1993 KluwerAcademic Publishers. Printed in the Netherlands. R53 DETERMINATION OF PRECISE GEOMETRIC CORRECTION FACTOR REGARDING STRESS INTENSITY BY A "FORCE BALANCE METHOD" D.L. Chen, B. Weiss and R. Stickler Institute for Physical Chemistry - Materials Science University of Vienna, W'dhringer Strasse 42 A-1090 Vienna, Austria tel: -222-34361725 For the solution to any fracture or crack growth problems one must know the geometric correction factors regarding stress intensity (K) for the structural crack of interest [1]. This is due to the fact that all of the engineering test specimens must have finite dimensions, resulting in the following modified general stress intensity expression: K =rm (i) where t~ is the externally applied stress, a is crack length, Y is geometric correction factor. There are several methods for the determination of the geometric correction factors, such as, finite element method, Green's function or weight function method, etc. However, the geometric correction factors obtained by these methods are usually of limited accuracy [1]. Thus there is a great need for simple methods to obtain more accurate geometric correction factors. Recently, we have established a new and simple method - "force balance method"- for the calculation of precise geometric correction factors [2,3]. Applying this approach, we have derived a new and exact geometric correction factor for a finite width center cracked plate loaded by a pair of splitting forces (see Fig. 1(a)) as follows: Y(2a/W) = 2cos-'(2a/W) where a is the half-crack length, W is the specimen width. In particular, the application of the proposed force balance method gives rise to a simple and precise geometric correction factor for commonly-used center cracked tension (CCT) specimens (see Fig. l(b)): (2) Int Journ of Fracture 59 (1993)