Effect of through Crack Size on Strength of Shell Structures

Abstract

The analysis of numerous cases of failure in shell structures has shown it occurs at stresses lower than the design stresses. The origin of these failures has been attributable to flaws or cracks. To determine which size of crack is admissible, one must study how the structural strength is affected by cracks. In this paper, the analysis is done using a finite-element program developed by the authors. The stress intensity factor, K, of the shell structure is calculated and compared with that of the theoretical one, and excellent results were achieved, as shown in the figures and tables of the results. The load-carrying capacity of cracked shell structures were also evaluated and compared with that of the uncracked shell structures’ capacity to determine the crack size that is admissible. The results obtained were also compared with that of theoretical solutions, and excellent results were achieved, as shown in the figures. The elements used in this program are eight-nodes shell elements, six-nodes singular triangular shell elements, and eight-nodes transition singular shell element, all elements with a 5 degree of freedom per node.