1、BSI Standards PublicationBS ISO 18459:2015Biomimetics Biomimeticstructural optimizationBS ISO 18459:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 18459:2015. The UK participation in its preparation was entrusted to TechnicalCommittee AMT/-/4, Biomimetics
2、.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2015.Published by BSI Stand
3、ards Limited 2015ISBN 978 0 580 81321 4 ICS 07.080 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2015.Amendments/corrigenda issued since publicationDate
4、 T e x t a f f e c t e d ISO 2015Biomimetics Biomimetic structural optimizationBiomimtisme Optimisation biomimtiqueINTERNATIONAL STANDARDISO 18459First edition 2015-05-15Reference number ISO 18459:2015(E)BS ISO 18459:2015ISO 18459:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT IS
5、O 2015, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permiss
6、ion. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 18459:2015ISO 18459:2
7、015(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Symbols and abbreviated terms . 35 Principles of self-optimization in nature and hence transferred optimization methods 36 Application of methods 56.1 Application range and limits . 56.2 Computer Aided Opt
8、imization (CAO) 66.2.1 Stress-controlled growth 66.2.2 Shrinking 76.2.3 Finite elements in practical applications (FEA) 86.3 Soft Kill Option (SKO) 86.3.1 Principle of the SKO method 86.3.2 Implementing the SKO principle in the finite element analysis 96.3.3 Examples of applications of the SKO metho
9、d .116.4 Computer Aided Internal Optimization (CAIO) .126.4.1 Example of the CAIO method: bent cylinder .136.5 Method of Tensile Triangles 146.5.1 General. 146.5.2 Tensile triangles for saving material156.5.3 Tensile triangles for optimization of fibre orientation 176.5.4 Example of the Method of Te
10、nsile Triangles: shoulder fillet .18Bibliography .20 ISO 2015 All rights reserved iiiContents PageBS ISO 18459:2015ISO 18459:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Inter
11、national Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison wit
12、h ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives,
13、 Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of t
14、he elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations
15、received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs
16、 adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 266, Biomimetics.iv ISO 2015 All rights reservedBS ISO 18459:2015ISO 18459:2015(E)IntroductionBiomimetic optimiza
17、tion methods are based on the knowledge gained from studying natural biological structures and processes.Structural optimization is a special branch of optimization dealing with the ideal design of components while taking the current boundary conditions into account. Commonly optimized properties in
18、clude the weight, the load capacity, the stiffness, or the lifespan. The goal is to optimize one or more of these properties by maximizing or minimizing their values.Generally, the idea is to utilize the construction material as efficiently as possible while avoiding overloaded and underloaded areas
19、. Since almost every technical component for functional reasons exhibits changes in section and, hence, notches, minimizing notch stress is especially important in structural optimization. In classic structural optimization, the notch shape factor, i.e. the stress concentration factor on the notch,
20、is reduced by selecting the largest possible radius of curvature for the notch or by utilizing the mutual interaction of notches and adding relief notches. The shapes of the notches are not changed by this procedure. The use of other notch shapes (Baud curves, ellipses, logarithmic spirals, etc.) wa
21、s suggested as early as in the 1930s. But they are not widely applied in technology and are only used occasionally.Computer-based biomimetic optimization tools, such as Computer Aided Optimization (CAO) and the Soft Kill Option (SKO), modify the shape and topology of the component, respectively, and
22、 thus homogenize the stresses using the finite element analysis (FEA). Such tools have been available since 1990 and are used in industry. The need to use FEA for optimization in this case limits the number of possible users, though, because a powerful computer, special software, and an expert are n
23、eeded for its operation. The demand for even simpler and faster methods that cannot only be used by specialists to optimize components, but also by design engineers, led to the development of the “Method of Tensile Triangles”. Although development of this method began in 2006 only, it is already bei
24、ng used for verified applications because it is easy to understand and apply. The wide range of applications of biomimetic optimization methods together with the relative ease with which users are able to understand and apply the methods enables users to perform component optimization early in the d
25、esign process. In the case of the Tensile Triangle Method, this is possible simply by implementing the method in CAD systems.As every optimization means specialization for the selected cases of load, service loading can be well known. Other unconsidered loading conditions might even result in higher
26、 stresses in a component. ISO 2015 All rights reserved vBS ISO 18459:2015ISO 18459:2015(E)BS ISO 18459:2015Biomimetics Biomimetic structural optimization1 ScopeThe International Standard specifies the functions and scopes of biomimetic structural optimization methods. They consider linear structural
27、 problems under static and fatigue loads. The methods described in this International Standard are illustrated by examples.Based on the biological model of natural growth and by use of the FEM optimization methods for technical components, computer-based biomimetic optimization tools are described a
28、s Computer Aided Optimization (CAO), Soft Kill Option (SKO), and Computer Aided Internal Optimization (CAIO). The purpose of these methods is an optimal materials application for weight reduction or enhanced capability and lifespan of the components.Additionally, a simpler and faster “Method of Tens
29、ile Triangles” is described that can be used by every design engineer. The wide range of applications of biomimetic optimization methods together with the relative ease with which users are able to understand and apply the methods enables users to perform component optimization early in the design p
30、rocess.The purpose of this International Standard is to familiarize users with biomimetic optimization methods as effective tools for increasing the lifespan, reducing the weight of components, and promoting the widespread use of these methods in support of sustainable development.This International
31、 Standard is intended primarily for designers, developers, engineers, and technicians, but also for all persons entrusted with the design and evaluation of load-bearing structures.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are
32、indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 18458, Biomimetics Terminology, concepts and methodologyISO 2394, General principles on reliability fo
33、r structuresISO 4866, Mechanical vibration and shock Vibration of fixed structures Guidelines for the measurement of vibrations and evaluation of their effects on structuresISO 13823, General principles on the design of structures for durability3 Terms and definitionsFor the purposes of this documen
34、t, the following terms and definitions apply.3.1mechanical adaptive growthappropriate reaction of biological structures, such as trees and bones, to changing conditions (e.g. mechanical loads) by locally adding material to high-stress areas or removing material from low-stress areasEXAMPLE Thicker a
35、nnual rings.3.2algorithmprecisely described procedure to complete a task in a finite number of stepsINTERNATIONAL STANDARD ISO 18459:2015(E) ISO 2015 All rights reserved 1BS ISO 18459:2015ISO 18459:2015(E)3.3design spacevolume available for a componentNote 1 to entry: The edges of the component to b
36、e designed shall not extend beyond the limits of the design space.3.4Computer Aided Internal OptimizationCAIOmethod based on the finite element analysis (3.6) for the optimization of the local fibre orientation in fibre composites with the goal of increasing their load capacity3.5Computer Aided Opti
37、mizationCAOmethod for optimizing the shapes of components based on the finite element analysis (3.6)Note 1 to entry: The stresses in highly stressed areas, such as notches (3.8), are reduced and the component lifespan is increased.3.6finite element analysisFEAnumerical method for obtaining approxima
38、te solutions of partial differential equations subject to boundary conditionsNote 1 to entry: In the engineering sciences, it is used as an analysis method, for example, to answer questions relating to structural mechanics. With FEA, a complex structure is divided up using small, simple, and interli
39、nked elements (FEA mesh). When boundary conditions (loads, bearings, etc.) and material properties are defined, it is possible to calculate stresses, deformations, etc. in any section of the complex structure.3.7shape optimizationmodification of the surface of the component to modify a certain targe
40、t function in a defined manner (for example, to minimize stresses)3.8notchconcavities in components that weaken a component locally due to the notch effect (3.9)Note 1 to entry: Such weak points are not desired in most cases, but notches are used as predetermined breaking points in certain cases in
41、order to specify where the component should fail and to limit the load that can be placed on the component.3.9notch effectlocal arising of stress peaks on notches (3.8) subjected to a loadNote 1 to entry: The height of the peak usually depends on the size and shape of the notch (3.8). The stresses d
42、ecrease as the curvature is decreased and as the size of the notch (3.8) contour is increased.3.10Method of Tensile Trianglessimple graphical method for homogenizing stresses in componentsNote 1 to entry: It can be used to reduce stresses in high-stress areas, for example, on notches (3.8), and incr
43、ease the component lifespan, as well as to remove underloaded areas and save material.2 ISO 2015 All rights reservedBS ISO 18459:2015ISO 18459:2015(E)3.11Soft Kill OptionSKOmethod for optimizing the topology (3.12) of components based on the finite element analysis (3.6)Note 1 to entry: Lightweight
44、design proposals are generated by successively removing low-stressed material from the design space (3.3).3.12topologyrelationship (position and orientation, for example) between the structural elements (holes, supports, etc.) of a component4 Symbols and abbreviated termsE modulus of elasticityE var
45、iation of the modulus of elasticity, E = f()F forceM torqueT (x,y,z) thermal load coefficient of thermal expansionmisesequivalent stress according to von Mises5 Principles of self-optimization in nature and hence transferred optimization methodsWith the help of the finite element analysis (FEA), num
46、erous studies of biological load-bearing structures, such as trees, bones, claws, and thorns, revealed that these load-bearing structures are optimally adapted to the stresses they are subject to and that the same design principles apply to all structures. The axiom of uniform stress has been shown
47、to be a fundamental principle that applies when load-bearing biological structures, such as trees or the bones of mammals, grow. This axiom states that the surface of a load-bearing structure will not exhibit weak points (areas under high stress) or underloaded areas (unnecessary ballast or wasted m
48、aterial) so that a uniform stress is applied to the surface. This mechanically advantageous stress state is realized through adaptive growth. Trees, for example, detect local stress concentrations using internal receptors and repair themselves by growing adaptively. On overloaded areas, they grow an
49、nual rings that are thicker locally and therefore reduce stress peaks. However, trees cannot remove superfluous material from areas relieved of stress, in contrast to the bones of humans and animals.The self-optimization of biological structures is not limited to their exterior structure; even their inner structures are superbly adapted to the stresses they are subjected to. Adaptive mineralization processes in bones make areas subject to higher stresses stiffer, while less stressed areas are softened and finally removed.In general, biological ma
