Correction of equivalent elastic-plastic anisotropic properties of thick tubesheets to preclude overstiff response to monotonic loading

摘要

Plastic design methods provide the designer with much more detailed stress and strain information than other methods and can therefore result in designs which are both safer and more economical. Because of the advances in computer hardware and finite element software, in recent years, these methods are now almost routine. The design of thick tubesheets adds some complexity to such analyses because the perforated section must be modelled as a continuum with equivalent properties. A technique for determining the elastic-plastic anisotropic properties of perforated plates has been reported in the literature. This modelling technique is shown to be quite adequate for the elastic portion of the solution, irrespective of the biaxiality. For the plastic portion, which is based on Hill's deformation plasticity theory, this technique has also been shown to be adequate when the biaxiality is not positive. For the case of positive biaxiality, however, the equivalent properties are over-stiff and can result in the plastic strains being unconservative. A method of correcting the elastic-plstic anisotropic properties to preclude this over-stiff response for monotonic loading is presented in this paper.