1、 Reference number ISO/TR 10771-2:2008(E) ISO 2008TECHNICAL REPORT ISO/TR 10771-2 First edition 2008-12-01 Hydraulic fluid power Fatigue pressure testing of metal pressure-containing envelopes Part 2: Rating methods Transmissions hydrauliques Essais de fatigue des enveloppes mtalliques sous pression
2、Partie 2: Mthodes de classement ISO/TR 10771-2:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the comp
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6、ssion in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office 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 reser
7、vedISO/TR 10771-2:2008(E) ISO 2008 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 2 4 Selection of material factors 2 5 Determination of cyclic test pressure. 2 6 Conduct of fatigue test. 3 7 Rating by similarity. 4 8 R
8、ating declaration. 4 9 Identification statement (reference to this part of ISO 10771) . 4 Annex A (informative) Material factor database 5 A.1 Values of coefficient of variation, k o , for commonly used metals . 5 A.2 Procedures used to establish values of coefficient of variation, k o , for the met
9、als listed in Table A.1 5 Annex B (normative) Calculation of variability factor K V 13 B.1 General. 13 B.2 Method . 13 Annex C (informative) Proposal for an acceleration factor 15 C.1 General. 15 C.2 Extrapolating data to 10 7cycles . 15 C.3 Examples . 19 Annex D (informative) Basis of fatigue press
10、ure rating 921 D.1 Basis of pressure rating. 21 D.2 Statistical analysis theory 22 D.3 Fatigue distribution data 28 D.4 Data calculation example. 33 D.5 Raw data points for sample problem 39 Bibliography . 40 ISO/TR 10771-2:2008(E) iv ISO 2008 All rights reservedForeword ISO (the International Organ
11、ization 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 establish
12、ed 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 standardization.
13、 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 voting. Pu
14、blication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. In exceptional circumstances, when a technical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for e
15、xample), it may decide by a simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature and does not have to be reviewed until the data it provides are considered to be no longer valid or useful. Attention is drawn to the poss
16、ibility 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 patent rights. ISO/TR 10771-2 was prepared by Technical Committee ISO/TC 131, Fluid power systems, Subcommittee SC 8, Product testing. ISO/TR 1077
17、1 consists of the following parts, under the general title Hydraulic fluid power Fatigue pressure testing of metal pressure-containing envelopes: Part 1: Test method Part 2: Rating methods ISO/TR 10771-2:2008(E) ISO 2008 All rights reserved vIntroduction In hydraulic fluid power systems, power is tr
18、ansmitted and controlled under pressure within a closed circuit. It is important for the manufacturer and user of hydraulic components to have information on their global reliability because of the importance of the fatigue failure mode and the relationship with their functional safety and service l
19、ife. This part of ISO 10771 provides a method for fatigue-testing in order to verify the rating of a pressure-containing envelope. During operation, components in a system can be subjected to loads that arise from: internal pressure; external forces; inertia and gravitational effects; impact or shoc
20、k; temperature changes or gradients. The nature of these loads can vary from a single static application to continuously varying amplitudes, repetitive loadings and even shocks. It is important to know how well a component can withstand these loads, but this part of ISO 10771 addresses only the load
21、s due to internal pressure. There are several International Standards already in existence for pressure rating of individual components (e.g. for determining maximum allowable rated pressure) and this part of ISO 10771 is not intended to replace them. Instead, a method of fatigue verification is pro
22、vided. This part of ISO 10771 describes a universal verification test to give credibility to the many in-house and other methods of determining the pressure rating of the components. Credibility is based upon the fundamental nature of metal fatigue with its statistical treatment and a mathematical t
23、heory of statistical verification. Nevertheless, it is necessary to have design knowledge of the component and its representative specimens to maximize accuracy of the verification method. The use of this test method can reduce the risk of fatigue failure for a hydraulic component regardless of samp
24、le size. In order to rate components in accordance with this part of ISO 10771, it is necessary to propose a rating for the component, select test specimens and select a test pressure. A fatigue test is then conducted in accordance with ISO 10771-1. If the test is successful, the proposed rating is
25、verified for the family of components represented by the sample. This part of ISO 10771 is based on ANSI/(NFPA) T 2.6.1, a standard which was developed and has been used in the United States for over 25 years and has been adopted for use in Japan as JSME S006-1985. If sufficient experience is gained
26、 in other parts of the world, and additional data on materials are obtained, this part of ISO 10771 might be re-drafted as an International Standard in the future. It should be noted that the test factors in Annex A are based on material data obtained from sources originating in the USA. One of the
27、objectives in issuing this part of ISO 10771 is to obtain material data from other countries. The test factors are based only on the material properties and not on any tolerances of the elements in the pressure-containing envelope. Annex C describes a possible method for accelerating testing. The ex
28、ample shows how material property data can be used to determine an acceleration factor and shows that they have to be carefully chosen. Another objective of this part of ISO 10771 is to seek additional data as described in Annex C. Contributors are asked to submit any available data to the secretary
29、 of ISO TC 131/SC 8. TECHNICAL REPORT ISO/TR 10771-2:2008(E) ISO 2008 All rights reserved 1Hydraulic fluid power Fatigue pressure testing of metal pressure-containing envelopes Part 2: Rating methods 1 Scope This part of ISO 10771 specifies a test method for fatigue rating of the pressure-containing
30、 envelopes of components used in hydraulic fluid power systems, as tested under steady internal cyclic pressure loads in accordance with ISO 10771-1. This part of ISO 10771 is only applicable to components whose failure mode is the fatigue of any element in the pressure-containing envelope, and that
31、: are manufactured from metals; are operated at temperatures that exclude creep and low-temperature embrittlement; are only subjected to pressure-induced stresses; are not subjected to loss of strength due to corrosion or other chemical action; can include gaskets, seals and other non-metallic compo
32、nents; however, these are not considered part of the pressure-containing envelope being tested (see note 3 of 5.5 of ISO 10771-1:2002). This part of ISO 10771 does not apply to piping as defined in ISO 4413 (i.e. connectors, hose, tubing, pipe). NOTE See ISO 19879, ISO 6803 and ISO 6605 for methods
33、of fatigue testing of tube connectors, hoses and hose assemblies. This part of ISO 10771 establishes a general rating method that can be applied to many hydraulic fluid power components. In addition, EN 14359 has been developed for accumulators. 2 Normative references The following referenced docume
34、nts are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 5598, Fluid power systems and components Vocabulary ISO 10771-1:2002, Hydrau
35、lic fluid power Fatigue pressure testing of metal pressure-containing envelopes Part 1: Test method ISO/TR 10771-2:2008(E) 2 ISO 2008 All rights reserved3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 5598, ISO 10771-1 and the following apply. 3.1 ra
36、ted fatigue pressure P RFmaximum pressure that a component pressure-containing envelope, selected at random, has been verified to sustain for the rated cycle life without failure, with a known probability 3.2 assurance level probability that the fatigue strength of a randomly selected test specimen
37、exceeds its rated fatigue pressure 3.3 verification level probability that the fatigue strength of a randomly selected test specimen is not less than its cyclic test pressure 3.4 coefficient of variation k ostandard deviation of the fatigue strength distribution of a material at a given fatigue life
38、, divided by its mean NOTE Adapted from ISO 3534-1:2006 1 . 3.5 variability factor K Vratio of cyclic test pressure to rated fatigue pressure 3.6 element part of a component; for example, tie rods on a cylinder, end caps on a valve, bolts on a pump housing 4 Selection of material factors 4.1 Select
39、a coefficient of variation, k o , for each type of material in the pressure-containing envelope. The k ofactor should be obtained from fatigue tests on coupons for the particular temper of material used in the pressure-containing envelope. The fatigue test method used to obtain this data should be i
40、n accordance with a recognized national or International Standard. 4.2 As an alternative to testing the specific material, coefficients described in Annex A can be used for the k ofactor. 5 Determination of cyclic test pressure 5.1 Select an assurance level for the fatigue pressure rating. A nominal
41、 value is 90 %. 5.2 Select a verification level for the fatigue pressure rating. A nominal value is 90 %. NOTE See Annex D for a tutorial that describes these terms. 5.3 Select a number of component specimens to be tested, then determine the number of element specimens that will be tested in the com
42、ponents. NOTE The verification is independent of sample size because the test pressure compensates for different quantities. ISO/TR 10771-2:2008(E) ISO 2008 All rights reserved 35.4 Determine the variability factor, K V , for each element in the component using Table 1 and the procedure described in
43、 the example given in Annex B. Use the largest K Vfactor so obtained, for the calculations described in the example. 5.5 Propose a rated fatigue pressure for the pressure-containing envelope of the component. 5.6 Calculate the cyclic test pressure, P CT , using Equation (1): CT V RF PKP = (1) where
44、K Vis the variability factor; P RFis the rated fatigue pressure of the component pressure-containing envelope. Table 1 Variability factor, K V(at a verification level of 90 %)Material coefficient of variation, k o b Assurance level No. of specimens n a0 0,02 0,04 0,06 0,08 0,10 0,12 0,14 0,16 0,18 0
45、,20 0,22 0,24 0,26 0,28 0,30 1 1,001,09 1,20 1,321,461,631,832,082,382,773,29 2 1,001,08 1,16 1,261,381,521,681,882,132,452,87 3 1,00 1,07 1,15 1,23 1,34 1,46 1,61 1,78 2,01 2,29 2,66 3,18 4 1,00 1,06 1,13 1,22 1,31 1,42 1,56 1,72 1,93 2,19 2,54 3,02 99,9 % 5 1,00 1,06 1,13 1,20 1,29 1,40 1,53 1,68
46、1,87 2,12 2,44 2,89 1 1,00 1,08 1,16 1,25 1,35 1,47 1,60 1,75 1,92 2,12 2,35 2,63 2,96 2 1,00 1,06 1,12 1,20 1,28 1,37 1,47 1,58 1,72 1,87 2,05 2,26 2,52 2,85 3 1,00 1,05 1,11 1,17 1,24 1,32 1,40 1,50 1,62 1,75 1,90 2,09 2,31 2,59 2,94 4 1,00 1,05 1,10 1,15 1,21 1,28 1,36 1,45 1,55 1,67 1,81 1,98 2,
47、18 2,43 2,74 3,16 99 %5 1,00 1,04 1,09 1,14 1,20 1,26 1,33 1,41 1,51 1,62 1,75 1,90 2,08 2,31 2,60 2,98 1 1,00 1,05 1,11 1,17 1,23 1,29 1,36 1,44 1,52 1,60 1,69 1,79 1,89 2,00 2,12 2,25 2 1,00 1,04 1,07 1,11 1,16 1,20 1,25 1,30 1,35 1,41 1,47 1,54 1,61 1,69 1,77 1,86 3 1,00 1,03 1,06 1,09 1,12 1,16
48、1,19 1,23 1,28 1,32 1,37 1,42 1,48 1,54 1,60 1,67 4 1,00 1,02 1,05 1,07 1,10 1,13 1,16 1,19 1,23 1,26 1,30 1,34 1,39 1,44 1,49 1,55 90 % 5 1,00 1,02 1,04 1,06 1,08 1,11 1,13 1,16 1,19 1,22 1,25 1,29 1,33 1,37 1,41 1,46 aTest twice the number of specimens if a 99 % verification level is chosen. bUse
49、an interpolation of k ovalues between those tabulated here, or calculate K Vfrom Equation (D.14) in Annex D. 6 Conduct of fatigue test 6.1 Determine the number of cycles, between 1 10 5and 1 10 7 , for which the component will be rated. 6.2 Subject the test specimens to a fatigue pressure test in accordance with ISO 10771-1 for the number of cycles determined in 6.1, using the P CTcalculated from Equation (1). ISO/TR 10771-2:2008(E) 4 ISO 2008
