The concept of "load relief factor" is used to determine in an approximate manner stress intensity factors for a multiply-cracked plane and an axisymmetric body. To demonstrate the validity of the method, which utiliies known available solutions, it is tirst shown to conservatively agree, within engineering accuracy, to that obtained from a more exact formulation. Stress intensity factors are then found for multiple-internal radial cracks in hollow cylinders of various wall ratios, stressed by internal pressure. Such a solution, although approximate and heretofore unavailable, wiII aid in ordnance design applications and serve as guidance until more rigorous analyses become available.
NOTATION R load relief factor = (K,),J(Kr),, (Kl,, the Mode I stress intensity factor for a multiplycracked body of infinite contiguration (K,l,, the Mode I stress intensity factor for the same infinite body and loading conditions as (K, l,,,,.. but having a single crack (K,),J the Mode I stress intensity factor for a single-cracked finite body of the same geometry and loading conditions as that represented by R (&L,J stress intensity factor, Mode 1. of a multiply-cracked finite body L length of an edge crack a tensile stress due to an axial force T cylinder wall thickness W wall ratio, defined as the outer cylinder radius divided by the inner cylinder radius 2n length of a center crack 26 width of a center cracked strip 2h crack pitch, defined as the distance between paraRe center cracks P applied pressure or stress r,, r, inner and outer radius, respectively of a hollow cylinder (K,),,&/a stress intensity ratio for a multiply center-cracked strip of finite width (K,),JpdL.
stress intensity ratio for a multiply radii-cracked cylinder of finite wall ratio (K,),JpvL stress intensity ratio for a single diametral-cracked cylinder of finite wall ratio UT crack length to cylinder wall thickness ratio Uq crack length to hole radius ratio a/b crack length to strip width of a center-cracked strip h/o crack pitch to length ratio of a center-cracked strip n number of cracks in a thick-walled cylinder