Finite Element Analysis of Thin-Walled Structures PDF

Preface

The aim of this book is to present a series of chapters that describe current developments in the finite element analysis and design of certain types of thin-walled structures. Each chapter is presented in a self-contained manner and concentrates on the practical aspects of finite elements and their use.

The choice of using the finite element method of analysis to the exclusion of other methods of analysis is, for the user, considerably eased by the ready availability of finite element analysis packages, coupled with the easy access to the required computing resources.

For engineers, an answer to within 10% of the correct answer is acceptable. To a mathematician, 1% is a large error, but mathematicians usually have alternative analytical solutions with which to calibrate their results. No such analytical calibration is available to an engineer who may be designing an air-inflated building, an axisymmetric thin shell, a ship’s hull or the leg of an oil-drilling platform.

In the analysis of shell structures using finite elements, which the editor researched for his Ph.D., care had to be taken to ensure that elements were always used within the boundaries of their theoretical development. This proved to be no easy task. Elements that gave accurate answers to, say, a shallow barrel-vault roof could be most inaccurate when used for a deep barrel-vault roof.

In design offices, engineers are under pressure, and rightly so, to produce safe and efficient designs. Engineers need to have a knowledge of the available finite elements and their associated software, together with an ability to detect and avoid incorrect numerical results. The first three chapters of this book are designed to assist in this process.

Chapter 1 lays the foundations for the development and the use of finite elements for thin-walled structures. Chapter 2 looks at the availability of finite element software packages and suggests caution with respect to their indiscriminate use. In Chapter 3 the necessity of validating the input data, the elements and the mesh arrangement to be used are discussed. The chapter even suggests the testing of the elements to be used.

In deciding which area of structures to apply the use of finite elements to, a library search revealed that, although there are over 50 books on finite elements and 13 or so books on thin-walled structures published in the UK, there was no one book bringing together both finite elements and thin-walled structures. This was surprising, considering the rapidly increasing use of structures, such as buildings, pipelines, ships and oil platforms that rely upon their in-plane stiffness to resist loading. The final four chapters of this book show how the finite element method is used to assist in the solution of these thin-walled structures.

Chapter 4 analyses membrane structures varying from cables under self weight to water-inflated dams and air-inflated buildings. In Chapter 5 an axisymmetric thin-shell element has been developed and applied to a series of problems. Chapter 6 shows in detail the relationship between the finite element method, the loads, stresses, analytical and experimental work on ship structures and how this relationship is changing the way in which ships are designed. Finally, Chapter 7 illustrates details of offshore structures that are most frequently analysed using thin-shell elements.

Author: Dr J W Bull