1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2015 SAE International All rights reserved. No part of this p
3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/MA2003 AEROSPACE STANDARD MA2003 Issued 1981-12 Reaffirmed 2015-08 Rotary Flexure
5、 Testing of Hydraulic Tubing Joints and Fittings RATIONALE MA2003 has been reaffirmed to comply with the SAE five-year review policy. INTRODUCTIONThis document was prepared following an ISO/TC20/SC10 agreement to describe a flexure fatigue test procedure which allows evaluation of various tube fitti
6、ng designs or material combinations. This evaluation is performed by fatigue testing the tube joints over a spectrum of bending stresses and then plotting the cycles to failure. This test procedure is intended for comparative evaluation of fatigue characteristics only, the qualification test procedu
7、re for tube fittings being specified in MA 2005. Other test methods may be used as long as they develop the same data as the rotary flexure test.1. SCOPE:This standard establishes flexure test procedures to determine and classify the fatigue strengths of reconnectable or permanent hydraulic tube joi
8、nts.The procedure is intended for conducting flexure tests of fittings and joints with high strength hydraulic tubes of various alloys such as corrosion resistant steel, Nimonic, titanium and aluminum alloy hydraulic tube for use on commercial and military aircraft.A mean stress is applied by holdin
9、g system pressure in the specimens and then flexing in a rotary bending test machine. This test method conforms with ARP 1185 for inch-dimensioned tubing and fittings.2. REFERENCES:ISO 2964 Aircraft Tubing Outside Diameters and Thicknesses, Metric DimensionsMA 2005 Tube Fittings, Fluid Systems Separ
10、able, General Specification forARP 1185 Flexure Testing of Hydraulic Tubing Joints and FittingsSAE INTERNATIONAL MA2003 Page 2 of 11 3. REQUIREMENTS:3.1 Flexure Test Device:The test device should be capable of testing in-line or bulkhead union test specimens and other configurations such as elbows a
11、nd tees.The rotary flexure test device should be similar to that shown in Figure 1. Each rotary flexure test device should be capable of testing one specimen, but several specimens may be tested in parallel at one time.The device should be capable of constantly maintaining the required operating pre
12、ssure during the test. The test fluid shall be water or system fluid (working fluid) unless otherwise specified by the responsible authorities. A typical pressurization and automatic shutdown system is shown in Figure 2. The shutdown should be automatic in the event of failure or pressure drop. The
13、device should be capable of testing at controlled constant temperature, if specified by the procuring agency. The tailstock of the test device should be designed to permit alignment during initial installation and specimen mounting, and to serve as a pressure manifold. The rotating headstock should
14、have a low-friction, self-aligning bearing and should be designed to permit total deflections of up to 25 mm, and a constant rotational frequency within the range of 1500 to 3600 rpm. The base should be of rigid construction.3.2 Flexure Test Specimen:The test specimen should consist of an adapter fi
15、tting (headstock end), a section of straight tubing, and a test fitting at the tailstock end. Typical test specimens are shown in Figure 3. The tubing shall be of a size and wall thickness as specified by the user or procuring agency.SAE INTERNATIONAL MA2003 Page 3 of 11 FIGURE 13.3 Specimen Length
16、and Deflection Requirements:3.3.1 Specimen Length: The length “L“ of the specimens for rotary flexure testing shall be per Table I and measured as shown in Figure 1 or 3, depending on the fitting design.TABLE I - Test Specimen LengthSAE INTERNATIONAL MA2003 Page 4 of 11 FIGURE 2FIGURE 3SAE INTERNATI
17、ONAL MA2003 Page 5 of 11 FIGURE 4FIGURE 5SAE INTERNATIONAL MA2003 Page 6 of 11 3.3.1 (Continued):NOTE: The correlation between the strain gage reading and deflection may vary for different fitting designs. For example, a flareless fitting will show some movement in the fitting, whereas a weld joint
18、will be rigid. Also, a significant difference is noted if the S/N and D/N curves are compared for different tubing such as titanium alloy and corrosion resistant steel.3.3.2 Stress Determination: The desired strain or bending stress level for each set of specimens is induced by deflection of the spe
19、cimen in the headstock. The bending stress levels for the various deflection settings should be determined prior to applying pressure, using strain gauges and procedures as outlined in Section 4. Strain gauges should always be used unless continual use of the same specimens and equipment makes setti
20、ngs by dial indicator acceptable. Such settings by dial indicator, however, must be established in prior testing by the use of strain gauges. Strain gauges should be used whenever new test equipment is used or new tubing materials or tubing walls tested. A typical stress cycle is illustrated in Figu
21、re 6.3.3.3 Deflection: The specimen deflections required to induce the stress levels indicated in 4.2 are measured by dial indicator at the length “L“ as shown in Figure 1 or 3.NOTE: Established deflection settings may be used in lieu of stress determination by strain gauge whenever qualification te
22、sts are being conducted, or when deflection plotting is of particular interest, for example, to compare steel and titanium tubing.3.4 Method of Classification of Fittings According to S/N Flexure Performance:Fitting/tubing combinations should be classified by the characteristic curves as shown in Fi
23、gure 4, above which all S/N failure data points lie. Characteristic curves should be established per 4.2, showing cycles to failure for various bending stress levels.3.5 Method of Determining Deflection/Fatigue Strength:Cycles to failure should be plotted as shown in Figure 5, showing cycles to fail
24、ure for various deflection settings (deflection settings may correspond with bending stress levels used per 3.4).NOTE: Plotting of deflection in lieu of stress over cycles may be of interest to evaluate rigidity of fittings or compare the flexibility of different tubing materials such as corrosion-r
25、esistant steel and titanium.SAE INTERNATIONAL MA2003 Page 7 of 11 FIGURE 64. PROCEDURE:4.1 Preparation for Test:4.1.1 Instrumentation, Strain Gauges: Strain gauges should be mounted on each test specimen. The strain gauge type and location should be as follows:TYPES: For tube sizes through DN16: App
26、roximately 4 mmFor tube sizes DN20 and above: Approximately 8 mmLOCATION: The gauges should be mounted per Figure 1, 90 degrees apart.NOTE: Mounting of four gauges, in pairs on the X and Y axis is optional.4.1.2 Rotary Flexure Test Setup Centering: The exact outside diameter and wall thickness of th
27、e test specimen should be measured and recorded before the test. It is also recommended to check straightness, and if not straight, to reject or at least to mark the specimen in the plane where the tube end is not aligned.The tube assembly should be installed into the tailstock and the separate fitt
28、ings hand tightened to permit subsequent adjustments. The setup procedure is detailed as follows:Free-state microstrain readings should be measured and recorded.The self-aligning bearing at the headstock end should be roughly centered and the adapter inserted. The tailstock end should then be carefu
29、lly tightened so as to avoid moving the test specimen out of line.SAE INTERNATIONAL MA2003 Page 8 of 11 4.1.2 (Continued):The symmetry of the specimen should be maintained during the tightening procedure with the assistance of one, preferably two, dial indicators positioned on the driven end of the
30、tube. After tightening the adjustment bolts in the centered position, the symmetry must be checked in the horizontal and vertical positions. While turning the headstock by hand, each dial indicator should indicate less than + 0.08 mm nonsymmetrical deflection. For strain gauged specimens the microst
31、rain reading should deviate no more than 20 microstrain from the free state microstrain reading referred to above. For each checking the headstock shaft may be moved back and forth in its bearing. The shaft will move freely for properly aligned specimens.4.1.3 Flexure Deflection Measurement: The def
32、lection setting is measured by dial indicator as shown in Figure 1 and Table I.4.1.4 Operating Pressure: The specified system pressure is introduced after the tube bending settings are completed by using the strain gauge (S/N) or dial indicator (D/N) methods described under (3.) above.4.2 S/N Testin
33、g:4.2.1 Four sets of two specimens (specimen pairs) in each size should be subjected to flexure testing and the test results plotted on a semi-log plot, over a grid of S/N characteristic curves, as shown in Figure 4.4.2.2 A bending stress of 35% of the ultimate strength should be applied to the firs
34、t set of specimens.NOTE: The bend stress settings should be made prior to applying system pressure, which is to be maintained until failure or completion of the test.4.2.3 If the failure point for the first set lies between 5000 and 50,000 cycles, the bending stress should be reduced by approximatel
35、y 25% of the ultimate strength for the second test set.4.2.4 If the failure point for the second set lies between 200,000 and 1 million cycles, the bending stress should be lowered by increments of 2% for the third set.4.2.5 After two sets of data points are plotted, an examination of the data will
36、indicate the probable stress level for test sets number three and four. These levels should be selected to complete the S/N curve form, with one test set completing or exceeding 10 million flexure cycles. At least three sets should fail at less than 10 million cycles. In some cases, additional test
37、sets may be required to obtain the required data points, i.e., one set exceeding 10 million and three sets to fail under 10 million cycles.NOTE: After a failure, deflection and torque tightness of the fitting nut should be checked and recorded.SAE INTERNATIONAL MA2003 Page 9 of 11 4.3 Deflection/Fat
38、igue Testing:The same basic procedure should be followed as outlined under 4.2 above, except that the deflection settings are plotted over cycles to failure, as shown in Figure 5.5. EQUIPMENT:Suggested Test Fixtures:Photographs of a suggested set-up are shown in Figures 7 and 8.FIGURE 7SAE INTERNATI
39、ONAL MA2003 Page 10 of 11 FIGURE 8PREPARED BY SAE COMMITTEE G-3, AEROSPACE COUPLINGS, FITTINGS, HOSE, AND TUBING ASSEMBLIESSAE INTERNATIONAL MA2003 Page 11 of 11 APPENDIXEXPLANATORY REPORT - ISO/DIS 7525 ROTARY FLEXURE TESTING OFHYDRAULIC TUBING JOINTS AND FITTINGS1. At the fifth ISO/TC20/SC10 meeti
40、ng in Paris, October 1976 the U.S. delegation agreed to draft a procedure for flexure testing of hydraulic tube connections.2. The procedure had been previously coordinated and discussed as part of the test procedures for fluid fittings (N.55, N.66, N.93, N.110). It was then decided to develop a sep
41、arate document to cover this test method (Resolution #33). Subsequently, four drafts were coordinated in SC10 (N.135, N.308, N.258, N.299).3. The proposal is based on the ARP 1185 test method which is followed in the USA to approve hydraulic tube connections to MIL-F-18280 or ARP 1258.4. At the 1979 meeting of the SC10 there was agreement among the delegates from China, France, Germany, U.K., USSR, and the USA to release the final draft N.423, for coordination in TC20 as a DIS (Resolution #82).
