Equivalent In-Plane Shear Elastic-Plastic Properties of Thick Tubesheets

Abstract

Abstract In the design of tubesheets, using elastic-plastic analysis methods, inaccuracy in the equivalent in-plane shear properties will have little effect on the final analysis results. For the pressure loading involved in the design of tubesheets, the effects of anti-plane shear will be much more significant. However, when thermal effects of the no-tube-lane are to be taken into account, the accuracy of the in-plane shear properties may have a significant effect on results. In such a case, special care in modelling the anisotropy may be necessary in order to obtain accurate elastic-plastic solutions. Previous investigation (Slot and Branca, 1974) of the equivalent properties for perforated plates with a triangular pitch utilizes a finite element model that is a symmetric portion of a single ligament in order to limit computer run-times. The boundary conditions utilized in this investigation are, therefore, somewhat approximate because they do not represent the true repetitive symmetry of an infinite perforated plate. In addition, the previous work on in-plane shear properties does not take into account the variation in the equivalent properties resulting from hole pattern orientation with respect to the in-plane shear forces loading the ligaments. The purpose of this investigation is to study the effect of the extent of the model on the computed equivalent in-plane shear elastic-plastic properties for a thick perforated plate with a triangular pitch. In addition, a method is proposed for determining an integrated average equivalent in-plane shear property to allow a more accurate elastic-plastic analysis.