The Interaction Effect of Neighboring Holes or Cavities, With Particular Reference to Pressure Vessels and Rocket Cases

The problem treated in this paper is the following: If the strength of a member is reduced a certain amount by the presence of a single hole (or cavity), how close can a second hole (or cavity) be located relative to the first one without causing appreciable further reduction of the strength of the member? This problem arises in evaluating the results of nondestructive tests (x-ray, ultrasonic) of welds, forgings, and castings with regard to inclusions and porosity [1]. The available results for elastic stress distributions are reviewed; some estimates are made for examples for which solutions are not available. A complete solution of this problem must consider inelastic behavior and failure. In the absence of the needed information, it is believed that some guidance can be obtained from a comparison of elastic solutions, since we are concerned here with ratios (i.e., comparisons between one and two holes) rather than absolute strength determinations.