Technical Notes provide information on a technical issue of interest to RMA and, potentially, to a wider audience.
This technical note has been prepared to demonstrate how dimensional analysis can lead to a more rational and simplified way of understanding and describing the mechanics of a problem in structural analysis. The case of a rotating, solid, parallel-sided disc is considered. Finite element analysis is used to explore the relationship between the two non-dimensional groups for this problem.
Whereas elastic solutions are unique, limit analysis solutions are only unique in the sense of the collapse load. This means that there can be many different solutions (yield line patterns or moment fields) each having the same collapse load. This document shows some examples of multiple solutions in terms of yield line patterns and moment fields.
The process of stress linearisation was originally developed to assist practising engineers working in the design and analysis of pressure retaining equipment (pressure vessels, pipes, pumps, etc.) and, using general finite element models, to predict the stresses in these structures. In a mechanics of materials approach, structural forms such as pressure vessels are considered as shells and the codified assessment procedures, such as ASME, require the stresses to be cast in the form of stress resultants found in a shell member, i.e., membrane, bending shear resultants etc. When a pressure vessel, or similar, is analysed using continuum finite elements, then these stress resultants are not part of the standard output. These stress resultants may, however, be recovered by operating on the finite element stress field by the process of stress linearisation. The stress resultants may then further be operated on to obtain stress measures suitable for comparison with allowable limits prescribed in the codes of practice.
© Copyright 2017 Ramsay Maunder Associates. All Rights Reserved.