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/MA2006 AEROSPACE STANDARD MA2006 (ISO/DIS 8574) Issued 1988-08 Reaffirmed 2015-08
5、 Hydraulic Tubing - Qualification Test Requirements RATIONALE MA2006 has been reaffirmed to comply with the SAE five-year review policy. FOREWORDThis standard is a word-for-word equivalent of ISO/DIS 8574 with the exception of (1) deleting the option for torsion test, (2) adding subtitles, and (3) a
6、dding inch size tubing sizes and specimen lengths to Table I.Changes in this reaffirm are format/editorial only.1. SCOPE:1.1 Scope and Field of Application:This international standard establishes flexure and pressure impulse test procedures for determining and classifying the fatigue strengths of be
7、nt aircraft hydraulic tubing. The procedures are intended for use with high- and low-pressure system assemblies for evaluation of new materials or for qualification purposes.2. REFERENCE:2.1 SAE Publications:Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.MA2002 (ISO 6772) Impu
8、lse testing of hydraulic hose, tubing, and fitting assemblies3. DEFINITIONS:3.1 Terminology:Tube failure: Leakage or rupture of the tube itself during test. Failure of the tube coupling or at the coupling sleeve interface shall not constitute a tube failure.SAE INTERNATIONAL MA2006 Page 2 of 7 3.2 F
9、itting Failure:In the event of such a failure, the fittings shall be replaced and the test continued or a new specimen shall be tested.4. TEST EQUIPMENT:4.1 Flexure Test Equipment:The test equipment shall incorporate an electromechanical vibrator or other facility capable of providing planar vibrati
10、on at the required input within a frequency range of 5 - 250 Hz. The equipment shall also be capable of maintaining constant pressures up to system pressure in the test specimen using the applicable hydraulic fluid. It shall also provide an automatic shutdown facility to actuate at the failure of th
11、e specimen or significant leakage, and facilities for operating at various constant temperatures shall be available.4.2 Pressure Impulse Equipment:The test equipment shall be capable of producing the pressure impulse curve specified in MA2002 (ISO 6772).5. TEST SPECIMENS:5.1 Specimens for Flexure Te
12、sting:Test specimens shall consist of 90-degree bent lengths of the relevant tubing, as shown in Figure 1, manufactured using production techniques and requirements, plus test fittings and adaptors where required.5.2 Specimens for Impulse Testing:S-shaped specimens as shown in Figure 2 and Table 1 s
13、hall be used for impulse testing.5.3 Tube Bend and Material Data:The outside diameter and wall thickness of the tubing shall be measured and recorded, together with the ovality at the bend. The bend radius of the specimens shall be the minimum required by the particular aircraft project. In addition
14、, test samples after failure shall be sectioned and the wall thickness around the outside of the bend checked. Three samples of the test tubing shall also be checked to determine the basic material properties, that is, yield tensile strength (0.2% proof stress) and ultimate tensile strength and elon
15、gation.SAE INTERNATIONAL MA2006 Page 3 of 7 6. STRESS DETERMINATION (FLEXURE FATIGUE):6.1 Strain Gages, Type and Location:The desired bending stress level for each specimen is induced by deflection of the specimen and shall be determined using strain gages. The type and location of the strain gages
16、shall be as follows:Type: For the tube sizes up to and including 16 mm (5/8 in) outside diameter, use 4 mm (0.156 in) gage, maximum width. For tube sizes above 16 mm (5/8 in) outside diameter, use 6 mm (0.234 in) gage, maximum width.NOTE: the width of the gage must be compatible with the tube outsid
17、e diameter, that is 25% or less of tube diameter. Temperature effects shall be taken into account where necessary.Location: Two gages shall be mounted 180 degrees apart in the plane of maximum strain.6.2 Strain Gages, Position and Monitoring:The strain gages shall be positioned on the straight porti
18、on of the tube at a distance of4.5 mm 0.5 mm (0.177 in 0.02 in) from the bend as shown in Figure 1. Each pair of gages shall form half of a wheatstone bridge and shall measure bending stress only. The stress levels shall be monitored at regular intervals throughout the test period and, if any reduct
19、ion in stress levels is noted, then the lower value, prior to failure being evidenced, shall be used for plotting the S/N curve.7. TESTING:7.1 General:7.1.1 Proof Test: Prior to commencement of testing, the specimen tube assemblies shall be subjected to a proof pressure as required for the system op
20、erating pressure.7.1.2 Temperature: Unless otherwise specified (for example, MA2002 (ISO 6772), see clause 7.3), testing shall be carried out at ambient temperature unless the fatigue characteristics of the material in question are significantly affected by the extreme temperature limit envisaged, i
21、n which case the temperature spectrum shall be as defined by the particular aircraft requirements.7.2 Flexure Fatigue Testing:7.2.1 Number of Specimens, Plotting Bend Stress: A minimum of four sets of two specimens in each size shall be subjected to flexure testing, and the tensile stress due to ben
22、ding for each failure shall be plotted on a semilog plot. The recommended sequence for each set of two specimens is given in 7.2.3 (that is, one set of two specimens at each of the flexure cycle ranges).SAE INTERNATIONAL MA2006 Page 4 of 7 7.2.2 Application of Internal Pressure: The specimens shall
23、be pressurized to working pressure level before flexure is applied and a zero reading obtained from the gages.7.2.3 Failure Points, Preferred Distribution: In order to obtain adequate definition of the S/N curve, the following failure distribution is recommended:5000 to 50 000 cycles - 2 failures50
24、000 to 500 000 cycles - 2 failures minimum500 000 to 5 000 000 cycles - 2 failuresplus two specimens equaling or exceeding 10 000 000 cycles.7.3 Pressure Impulse Testing:7.3.1 Number of Specimens: A minimum of six specimens shall be subjected to pressure impulsing in accordance with MA2002 (ISO 6772
25、).7.4 Burst Test:7.4.1 Specimen Mounting and Pressurization Requirements: Specimens of each size shall be subjected to hydraulic pressure with one end free to move. The pressure shall be increased at a rate of 150,000 kPa (22,000 psi) per minute until tube burst. As a minimum requirement, each tube
26、shall withstand, without failure, a burst pressure as required by the system operating pressure plus any safety factor.8. ACCEPTANCE OF RESULTS:8.1 Flexure Fatigue:8.1.1 Use of S/N Data: The acceptability of the resulting S/N curve is dependent on the range and frequency of design stress levels dete
27、rmined for the aircraft in question. As a guide, the results obtained should demonstrate a fatigue life of 107cycles when subjected to constant working pressure plus alternating bending stresses of 100 MPa (14,500 psi) for steel and high strength alloy tube materials.8.1.2 Alternate Use of S/N Data:
28、 Alternatively, the S/N curve can be compared to previously used results in order to obtain a measure of acceptability.SAE INTERNATIONAL MA2006 Page 5 of 7 8.2 Pressure Impulse:8.2.1 Requirement: The required use is dependent on the life of the aircraft, but as a minimum requirement the results shou
29、ld demonstrate a life of 200,000 cycles when subjected to maximum impulse pressures as specified in MA2002 (ISO 6772).PREPARED BY SAE SUBCOMMITTEE G-3E, AEROSPACE TUBING INSTALLATION OF COMMITTEE G-3, AEROSPACE FITTINGS, HOSE AND TUBING ASSEMBLIESSAE INTERNATIONAL MA2006 Page 6 of 7 FIGURE 1 - Test
30、Specimen Showing Mounting Arrangement and StrainGage Configuration for Flexural Fatigue TestSAE INTERNATIONAL MA2006 Page 7 of 7 FIGURE 2 - S-Tube Specimen for Hydraulic Impulse TestTABLE 1 - Straight Length at Center and Total Specimen LengthsTube SizeDN (Dash)Straight at Center (CL)Total Tube Length+13, -0 mm +0.5, -0 in +25, -0 mm +1, -0 in06 (04) 65 2.5 300 10.7510 (06) 65 2.5 330 13.0012 (08) 90 3.5 400 15.0016 (10) 140 5.5 510 20.0020 (12) 140 5.5 570 22.2525 (16) 140 5.5 670 26.25
