“Effective Elastic Constants for Steam Generator Tube Sheets” W. J. O’Donnell, Bettis Technical Review, No. 22, p. 1, March 1961.
Keywords: steam generator; tube sheets; effective elastic constants; ligament efficiency
For purposes of analysis, perforated materials such as steam generator tube sheets are treated as solid materials having appropriate effective elastic constants (poisson ratio and elastic modulus). The values of these effective elastic constants differ for plane stress (in-plane) and bending loads, are dependent on the direction of the load with respect to the hole pattern as well as the ligament efficiency of the tube sheet.
The significance of these variations and their effect on calculated pressure and thermal stresses in the tube sheet and shell of a steam generator are examined. A single set of effective elastic constants applicable to both plane stress and bending loads on the tube sheet is presented. These constants can be used in the entire range of practical steam generator tube sheet dimensions and depend only on the ligament efficiency of the tube sheet.