Finite Element Analysis of Perforated Plates Containing Triangular Penetration Patterns of 5 and 10 Percent Ligament Efficiency

Two- and three-dimensional finite element models were used to determine elastic stress distributions in plate ligaments for various in-plane, bending, and thermal loadings. Plates containing triangular penetration patterns of 5 and 10 percent ligament efficiency were analyzed as well as the example of a circular plate containing a single centrally placed hole subjected to step change in temperature on one surface. Detailed descriptions of boundary conditions are given with the results presented in terms of stresses important in tubesheet and vessel closure design considerations. Results show that the minimum ligament section of the perforated region need not be the critically stressed cross section as is currently assumed in the ASME Boiler and Pressure Vessel Code. Further, a thermal shock ΔT applied to the surface of a perforated region will result in a maximum peak stress of EαΔT/(1−ν) and may be significantly lower than the thermal skin stress calculated by the ASME Code procedures.