Reliability of Multiphysical Systems Set
coordinated by
Abdelkhalak El Hami
Volume 5
First published 2017 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.
Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:
ISTE Ltd
27-37 St George’s Road
London SW19 4EU
UK
www.iste.co.uk
John Wiley & Sons, Inc.
111 River Street
Hoboken, NJ 07030
USA
www.wiley.com
© ISTE Ltd 2017
The rights of Ghias Kharmanda and Abdelkhalak El Hami to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.
Library of Congress Control Number: 2016952066
British Library Cataloguing-in-Publication Data
A CIP record for this book is available from the British Library
ISBN 978-1-78630-025-6
The integration of structural optimization into biomechanics is a truly vast domain. In this book, we first focus on the integration of structural optimization into the design of orthopedic and orthodontic prostheses, and also into drilling surgery. Next, we present the integration of reliability and structural optimization into the design of these prostheses, which may be considered as a novel aspect introduced in this book. The applications are made in 2D and in 3D, considering the three major families of structural optimization: sizing-, shape- and topology optimization.
In all domains of structural mechanics, good design of a part is very important for its strength, its lifetime and its use in service. This is a challenge faced daily in sectors such as space research, aeronautics, the automobile industry, naval competition, fine mechanics, precision mechanics or artwork in civil engineering, and so on. To develop the art of the engineer requires enormous effort to continuously improve the techniques for designing structures. Optimization is of primary importance in improving the performance and reducing the weight of aerospace- and automobile engines, providing substantial energy savings. The development of computer-aided design (CAD) techniques and optimization strategies is part of this context.
Applying structural optimization is still somewhat complicated in certain domains. Furthermore, in deterministic structural optimization, all parameters which are uncertain in nature are described by unfavorable characteristic values, associated with safety coefficients. The deterministic approach uses a pessimistic margin determined as a function of the consequences of a probable failure. This approach often leads to unnecessary oversizing – particularly for sensitive structures.
On the other hand, researchers have developed a different approach which is better suited to uncertain physical phenomena. In this approach, the structure is deemed to have failed if the probability of failure is greater than a fixed threshold. This is known as the “probabilistic approach”. The probabilistic approach is increasingly widely used in engineering, as evidenced by the different applications in industry. It is applied to check that the probability is sufficient when the structure’s geometry is known, or to optimize the sizing of the structure so as to respect certain fixed objectives, such as a target cost or a required level of probability.
Furthermore, reliability analysis is an important tool in decision-making for establishing a maintenance- and inspection plan. In addition, it can be used in the validation of standards and regulations. To perform reliability analysis, various methods can be used to effectively and simply find the probability of failure. Reliability analysis is a strategy used to evaluate the level of reliability without being able to control the design for a required reliability level. For this, reliability has become an important tool to be integrated into the process of structural optimization.
This book also focuses on the necessary tools for the integration of reliability and structural optimization into biomechanics fields. First, the deterministic strategies of structural optimization are presented so we can implement them in structural design. These deterministic strategies are applied in various domains in biomechanics, including the design of orthopedic and orthodontic prostheses and drilling surgery. Next, reliability-based approaches pertaining to the integration of reliability into structural optimization are presented in detail, with mechanical applications. These reliability-based strategies are also applied in the design of orthopedic and orthodontic prostheses, taking account of uncertainty in terms of geometry, materials and load. Finally, system reliability strategies are also taken into account, considering several failure scenarios.
The book will provide invaluable support to teaching staff and researchers. It is also intended for engineering students, practising engineers and Masters students.
We would like to thank all of those people who have, in some way, great or small, contributed to the writing of this book – in particular, Sophie Le Cann, a researcher at the Biomedical Centre (BMC) at Lund University, for her contribution in terms of biological language. Heartfelt thanks go to our families, to our students, and to our colleagues for their massive moral support during the writing of this book.
Ghias KHARMANDA
Abdelkhalak EL-HAMI
October 2016