1、 Reference number ISO 21648:2008(E) ISO 2008INTERNATIONAL STANDARD ISO 21648 First edition 2008-12-01 Space systems Flywheel module design and testing Systmes spatiaux Conception et essai du module de volant moteurISO 21648:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In acco
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6、fice Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reservedISO 21648:2008(E) ISO 2008 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Terms, definit
7、ions, symbols and abbreviated terms. 1 2.1 Terms and definitions. 1 2.2 Symbols . 5 2.3 Abbreviated terms 6 3 Requirements 6 3.1 General requirements. 6 3.2 Design requirements 7 3.3 Requirements for materials . 11 3.4 Fabrication and process control. 14 3.5 Quality assurance. 15 3.6 Repair and refu
8、rbishment 16 3.7 Storage requirements. 16 3.8 Transportation requirements. 16 4 Verification requirements 17 4.1 Design requirements verification 17 4.2 Qualification tests. 20 4.3 Acceptance tests 24 Bibliography . 28 ISO 21648:2008(E) iv ISO 2008 All rights reservedForeword ISO (the International
9、Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been esta
10、blished has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardiza
11、tion. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for votin
12、g. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such
13、patent rights. ISO 21648 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 14, Space systems and operations. ISO 21648:2008(E) ISO 2008 All rights reserved v Introduction Flywheels are mechanical devices that store kinetic energy in a rotating mass. A simple
14、 example is the potters wheel, which was widely used by people in ancient times. The first use of such devices dates from between 3500 and 3000 BC. According to archaeological evidence, these early flywheels were built from wood, stone and clay. One type of potters wheel was a rim made from a unidir
15、ectional material (bamboo), wound in the hoop direction and embedded in a matrix (clay). This design option is clearly a foreshadowing of the later use of composites for their inherent strength and lightweight nature. It is, however, only since the 1970s that the use of flywheels as energy storage s
16、ystems has become the focus of serious attention from energy researchers due to the constant threat of a shortage of fossil fuel supplies. Today, a typical flywheel energy system consists of a flywheel rotor, a supporting device (magnetic bearing ball bearings, superconductor bearings or other types
17、 of bearings), a charge/discharge device (motor/generator) and a safety containment (housing). For space applications, due to weight constraints, the use of a bulky safety containment system is not necessarily a desirable design. Thus, from a safety point of view, the design of flywheel energy syste
18、ms needs to concentrate on reliability and longevity. Current flywheel energy storage technology is made possible by the use of high-strength, carbon-fibre-based composite materials in the rotor. Flywheel energy storage systems are designed to both control spacecraft attitude and to store energy fun
19、ctions which have historically been performed by two separate systems. The stored energy is needed for the dark portions of the orbit when the Earths shadow makes solar power unavailable for spacecraft. For many spacecraft, flywheels offer the potential to significantly reduce weight and extend serv
20、ice life. However, the use of composite materials, coupled with variations in design approaches and demanding operating conditions, combine to present certification challenges for the rotor assemblies. This International Standard establishes the design, analysis, material selection and characterizat
21、ion, fabrication, test and inspection of the flywheel module in a flywheel. Many requirements set forth in this International Standard can also be adapted by similar types of rotating machineries, but for different usage. The momentum wheels and momentum gyroscopes are typical examples. The implemen
22、tation of these requirements will ensure a high level of confidence in achieving safe operation and mission success for these critical hardware items. INTERNATIONAL STANDARD ISO 21648:2008(E) ISO 2008 All rights reserved 1 Space systems Flywheel module design and testing 1 Scope This International S
23、tandard establishes the design, analysis, material selection and characterization, fabrication, test and inspection of the flywheel module (FM) in a flywheel used for energy storage in space systems. These requirements, when implemented on a flywheel module, will ensure a high level of confidence in
24、 achieving safe operation and mission success. With appropriate modifications, this International Standard can also be applied to similar devices, such as momentum and reaction wheels and control-moment gyroscopes. The requirements set forth in this International Standard are the minimum requirement
25、s for flywheel modules in flywheels used in space flight applications. They are specifically applicable to the parts in the flywheel rotor assembly (FRA), including rim, hub and/or shaft and other associated rotating parts, such as the bearings and the motor generator rotor. The requirements are als
26、o relevant to the non-rotating parts, such as module housing, main suspension assembly (magnetic or rolling element bearings, superconductor bearings, etc.), motor stator, caging mechanism and sensors within the module housing, and backup bearings, if applicable. However, control and interface elect
27、ronics are not covered in this International Standard. 2 Terms, definitions, symbols and abbreviated terms 2.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1.1 A-basis allowable mechanical strength value above which at least 99 % of the popula
28、tion of values is expected to fall, with a confidence level of 95 % NOTE See also B-basis allowable (2.1.4). 2.1.2 acceptance tests required formal tests conducted on hardware items to ascertain that the materials, manufacturing processes and workmanship meet specifications 2.1.3 allowable load allo
29、wable stress allowable strain maximum load that can be accommodated by a structure/material without rupture, collapse or detrimental deformation in a given environment NOTE Allowable loads commonly correspond to the statistically-based minimum ultimate strength, buckling strength and yield strength,
30、 as applicable. ISO 21648:2008(E) 2 ISO 2008 All rights reserved2.1.4 B-basis allowable mechanical strength value above which at least 90 % of the population of values is expected to fall, with a confidence level of 95 % NOTE See also A-basis allowable (2.1.1). 2.1.5 catastrophic failure structural
31、failure event due to the rotor separation, or the rupture or collapse, of other flywheel rotor assembly components or assembly 2.1.6 composite material combination of materials which differ in composition or form on a macro-scale NOTE The constituents retain their identities in the composite, i.e. t
32、hey do not dissolve or otherwise merge completely into each other, although they act in concert. Normally, the composites can be physically identified and exhibit an interface between one another. 2.1.7 damage tolerance ability of structure/material to resist failure due to the presence of flaws for
33、 a specified period of unrepaired usage 2.1.8 damage tolerance life required period during which a part of a flywheel module, even containing a large undetected crack, is shown by analysis or testing not to fail catastrophically in the expected service load and environment 2.1.9 damage tolerance ana
34、lysis damage tolerance testing analysis/testing that is used to demonstrate damage tolerance life NOTE For metallic parts, this type of analysis is also referred to as safe-life analysis. 2.1.10 design safety factor multiplying factor to be applied to the limit load and/or maximum expected operating
35、 speed 2.1.11 fatigue life number of load cycles experienced in service that a defect-free part in a flywheel module can sustain before failure of a specified nature could occur NOTE The number of load cycles experienced in service can be flight loads, ground test loads and charge/discharge cycles.
36、2.1.12 flaw local discontinuity in a structural material EXAMPLE Crack, delamination, void. 2.1.13 flight-like test article test article that is built in accordance with a fabrication process identical to the flight hardware ISO 21648:2008(E) ISO 2008 All rights reserved 3 2.1.14 flywheel module FM
37、assembly of mechanical parts which support and spin the flywheel rotor assembly and which house the appropriate sensors, rotor support systems and motor, which with the appropriate avionics suite and software can act as a stand-alone functional flywheel unit NOTE A flywheel module typically includes
38、 the housing, main suspension system (magnetic or rolling element bearing, superconductor bearings), motor stator, caging mechanism, sensors and backup bearings, if applicable. 2.1.15 flywheel rotor assembly FRA assembly in a flywheel which consists of rim, shaft and/or hub, bearings, motor generato
39、r rotor and other associated parts that rotate under normal operation 2.1.16 fracture critical part classification of a part for manned space systems, which assumes that fracture or failure of that part resulting from occurrence of a crack-like defect would create a catastrophic hazard NOTE Such cla
40、ssification is required on components unless it can be shown otherwise, i.e. if the part (and subsequent parts it could fail) can be shown to be contained, or in the case of low released energy, or if the part is failsafe, or if there is only a remote possibility of significant crack growth on the p
41、art to begin with. 2.1.17 fracture control application of design philosophy, analysis method, manufacturing technology, quality assurance and operating procedures to prevent premature structural failure caused by the propagation of cracks or crack-like flaws during fabrication, assembly, testing, tr
42、ansportation and ground-handling and service 2.1.18 fracture mechanics engineering discipline that describes the behaviour of cracks or crack-like flaws in materials under stress 2.1.19 fracture toughness generic term for measurements of resistance to extension of a crack 2.1.20 impact damage damage
43、 in a non-metallic part within the flywheel module that is caused by an object striking the part or by the part striking an object 2.1.21 impact damage tolerance ability of the fracture critical non-metallic parts in the flywheel module to resist strength degradation due to the impact damage event 2
44、.1.22 initial flaw size maximum flaw size, as defined by non-destructive evaluation, that is assumed to exist for the purpose of performing a damage tolerance (safe-life) analysis or testing 2.1.23 key process parameter KPP critical process parameter that affects design and product characteristics I
45、SO 21648:2008(E) 4 ISO 2008 All rights reserved2.1.24 life factor factor by which the service life is multiplied to obtain total fatigue life or damage tolerance life NOTE Life factor is often referred to as a scatter factor that is normally used to account for the scatter of a materials fatigue or
46、crack growth rate data. It can also account for the dispersion of loading spectra parameters and other uncertainties, when appropriate. 2.1.25 limit load maximum expected external load, or combination of loads, that a rotating part can experience during the performance of a specified mission in spec
47、ified environments NOTE When a statistical estimate is applicable, the limit load is that load not expected to be exceeded at 99 % probability with 90 % confidence. 2.1.26 margin of safety MS margin of safety expressed as allow limit safe 1 k where allowis the allowable load; limitis the limit load;
48、 k safeis the design safety factor NOTE Load can mean stress or strain (see 2.1.3). 2.1.27 maximum expected operating speed MEOS maximum spinning speed that a part in a flywheel module is expected to experience during its normal operation NOTE Maximum expected operating speed is synonymous with limi
49、t speed. 2.1.28 maximum design speed MDS highest possible operating speed based on a combination of credible failures NOTE Maximum design speed is required for some manned systems to accommodate any combination of two credible failures that will affect speed. 2.1.29 non-destructive evaluation NDE process or procedure for determining the quality or characteristics of a material, part or assembly without permanently altering the subject or its properties NOTE In this International Standard, non-destructive evaluation is sy
