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 2012 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/J2705_201211SURFACE VEHICLE RECOMMENDED PRACTICE J2705 NOV2012 Issued 2005-10 Rev
5、ised 2012-11 Superseding J2705 OCT2002 Tire Quasi-Static Envelopment of Triangular/Step Cleats Test RATIONALE This document was developed as part of a set of Recommended Practices intended to allow modelers to determine the parameters required by any of the common tire models for calculating spindle
6、 loads given the road surface profile from a single set of experimental results, thus eliminating duplicate testing. This version addresses minor editorial problems found in the previous version. 1. SCOPE This SAE Recommended Practice describes a test method for determining properties of a non-rolli
7、ng tire quasi-statically enveloping either a set of triangular cleats or a single step cleat. In the case of the triangular cleats the normal force and vertical deflection of the non-rolling tire are determined. In the case of the step cleats the normal force, longitudinal force, and vertical deflec
8、tion of the non-rolling tire are determined. The method applies to any tire so long as the equipment is properly sized to correctly conduct the measurements for the intended test tire.1The data are intended for use in determining parameters for road load models and for comparative evaluations of the
9、 measured properties in research and development. NOTE: Herein, road load models are models for predicting forces applied to the vehicle spindles during operation over irregular pavements. Within the context of this document, forces applied to the pavement are not considered. 1.1 Procedures A single
10、 procedure is specified. The differences in the test from the standpoint of the two cleat designs are whether the wheel is free to rotate about the spindle and what data must be measured and reported. These are spelled out in the body of this document. 1.2 Test Machines This document is test machine
11、 neutral. It may be applied using any type of test machine capable of fulfilling the requirements stated in this document. The test machine must be capable of accommodating the tire sizes to be tested, along with the required cleats. NOTE: Test results are a function of the Tire/Wheel assembly, not
12、just a function of the Tire alone. 2. REFERENCES 2.1 Applicable Documents 1Proper cleat height sizing requires that the test tire only contact the test cleat, and not the surface to which the cleat is fastened. SAE J2705 Revised NOV2012 Page 2 of 10 The following publications form a part of this spe
13、cification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA)
14、, www.sae.org. SAE J2047 Tire Performance Technology SAE J2429 Free-Rolling Cornering Test for Truck and Bus Tires SAE 770870 The Effect of Tire Break-In on Force and Moment Properties, K. D. Marshall, R. L. Phelps, M. G. Pottinger, and W. Pelz, 1977 SAE 810066 The Effect of Aging on Force and Momen
15、t Properties of Radial Tires, M. G. Pottinger and K. D. Marshall, 1981 2.1.2 Other Publications Available in wall chart form as #TTMP-7/95 from the Rubber Manufacturers Association, 1400 K St., N.W., Washington, DC 20005. OSHA Standard 1910.177 - Servicing Multi-Piece and Single Piece Rim Wheels Ava
16、ilable from American National Standards Institute, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org. ISO/IEC 17025:2005 - General requirements for the competence of testing and calibration laboratories 3. DEFINITIONS The definitions that follow are of special meaning in
17、this document and are either not contained in other Recommended Practices or are worded somewhat differently in this practice. 3.1 CLEAT DIMENSIONS 3.1.1 Cleat Height (H) Cleat Height is the vertical distance from the crest of the cleat to the supporting Simulated Roadway, see Figures 1 and 2. 3.1.2
18、 Cleat Width (W) Cleat Width is the physical left-to-right width of the crest of the cleat. 3.2 TEST A test is the execution of the procedure described in this document one time on one tire at a single set of test conditions. SAE J2705 Revised NOV2012 Page 3 of 10 3.3 TEST PROGRAM A Test Program is
19、a designed experiment involving multiple tests of the type described in this practice.24. NOMENCLATURE Table 1 lists the symbols used in this document. For definitions not in Section 3 of this practice please see SAE J2047. TABLE 1 - SYMBOLS DEFINED Symbol Defined Term ZVertical Deflection FXLongitu
20、dinal Force FZNormal Force H Cleat Height Triangular Cleat Apex Half Angle p Inflation Pressure RlLoaded Radius Standard Deviation (Note Subscripts) W Cleat Width 5. LABORATORY QUALITY SYSTEM REQUIREMENT The laboratory performing the procedure specified in this document shall have a quality system e
21、ither conforming to ISO/IEC 17025 or which can be shown to be functionally equivalent to ISO/IEC 17025. The elements of such a system are assumed below and are not, therefore, specifically called out within this practice. 6. APPARATUS The required apparatus consists of a loading machine, a set of cl
22、eats, and test rims. 6.1 Loading Machine The loading machine consists of a tire loading and positioning system, a measuring system, a flat surface simulated roadway, and the space housing the machine, which shall be maintained at 22 C 2 C. 6.1.1 Loading and Positioning System The system shall mainta
23、in the tire with the tire/wheel plane within 0.05 of perpendicular to the simulated roadway during all loading. Loading shall produce normal forces accurate to within 1.0% of the test machines full-scale normal force range. The machines full-scale normal force range shall allow imposition of loads e
24、quivalent to at least 400% of the test requester specified 100% load. The machines hub must be fixed with respect to rotation about the wheel spindle when testing with the triangular cleats, as described in 6.2.1, and free to rotate around the spindle when testing with the step cleat that is describ
25、ed in 6.2.2. 2There are many experimental possibilities: repeated test of the same tire, tests of the same tire under multiple test conditions, tests of tires with different specifications (design details), application of this test as part of a series of different tests, etc. SAE J2705 Revised NOV20
26、12 Page 4 of 10 6.1.2 Measuring System This system shall measure normal force (FZ) to within 0.5% of the test machines full-scale normal force range, longitudinal force (FX) to within 0.5% of the test machines full scale longitudinal force range, and loaded radius (Rl) to within 0.5 mm.3The system s
27、hall have a normal force range that allows measurement of forces equivalent to those existing at 400% of the test requester specified 100% load. 6.1.3 Simulated Roadway The simulated roadway shall be a smooth flat surface, free of loose materials and deposits adapted for mounting the cleats used in
28、this test. The material of which the roadway is made is unimportant so long as the roadway satisfies the following criteria. 6.1.3.1 The roadway shall be large enough to fully support each of the cleats used in this test. 6.1.3.2 The roadway and its supporting structure shall be sufficiently rigid s
29、o as to not change appreciably in either transverse or longitudinal orientation or in curvature under the machines maximum applied normal force. 6.1.3.3 If the roadway can be translated in the longitudinal direction, it shall be provided with a lock or locks that prevent translation during this test
30、. 6.2 Cleats Detailed cleat design except for the contour of the surface interacting with the tire is the responsibility of the testing facility and may be done, as necessary, to allow adaptation and securing of the cleat to the simulated roadway. The design shall ensure that no point on the cleat d
31、eflects by more than 0.5% of the tire deflection during testing. The cleats shall have a smoothly machined surface. 6.2.1 Triangular Cleats The cleat cross sections shall be isosceles triangles as indicated in Figure 1. There shall be a set of five cleats with apex half angles of = 45, 60, 75, 80, a
32、nd 85. As noted in 10.1, the 75 and 85 cleats are optional in the standard test. The cleat height (H) shall be large enough such that at no time within the test does the tire come in contact with the simulated roadway, which supports the cleat. The cleat width (W) shall be sufficient to fully suppor
33、t the tire width in contact. The cleat crown radius shall be between 1.5 and 3.0 mm. The apex of the cleat shall lie on the vertical line from the spindle axis to the simulated roadway. FIGURE 1 - TRIANGULAR CLEAT 3Should the measuring system sense multiple forces and moments, the output shall be co
34、rrected for load cell interaction by a matrix method conceptually equivalent to that discussed in SAE J2429. SAE J2705 Revised NOV2012 Page 5 of 10 6.2.2 Step Cleat The cleat shall be a step as indicated in Figure 2. The cleat height (H) shall be large enough that at no time within the test does the
35、 tire come in contact with the simulated roadway, which supports the cleat. The cleat width (W) shall be sufficient so as to fully support the tire width. The cleat corner radius shall be between 1.5 and 3.0 mm. The step cleat and/or cleats shall permit testing at longitudinal offsets of 0% of the t
36、ires unloaded radius, -10% of the tires unloaded radius, and +10% of the tires unloaded radius. FIGURE 2 - STEP CLEAT 6.3 Test Wheels Test wheels shall meet the dimensional tolerances of original equipment wheels supplied on new vehicles and shall match the rim profile for the applicable tire as spe
37、cified by the appropriate tire and rim standards association, for example, the Tire and Rim Association, Inc. NOTE: Wheel stiffness may have a discernable influence on the results. At this time, the presence of this effect has not been established. Further, there is not now a recognized way to appro
38、priately characterize wheel stiffness for use in this document. It is planned to address this question by research carried out prior to the five-year review of this practice. 7. CALIBRATION4Calibrate all measuring system components in accordance with the mandates of the written plan required by the
39、laboratory quality system referenced in Section 5. Calibration must exercise all measuring system components over substantially their full range of application and must be performed at least once each year. The reference standards and instruments used in measuring system calibration shall be traceab
40、le to the National Institute of Standards and Technology or the appropriate national standards organization with currently valid calibration certificates on file in the testing laboratorys files when the systems calibration is performed. Gains, offsets, and other pertinent performance measures and c
41、omments on system behavior during calibration shall be kept permanently on file within the testing laboratorys archives and be available to customers on request. 8. PREPARATION OF APPARATUS5Preparation of the apparatus shall ensure that the test equipment meets its calibration at the outset of each
42、test program. The precise process control method used to verify readiness of the apparatus is likely to be unique to an individual test site, but must be specified in writing within the quality system of the laboratory. The results of process control experiments shall be available to customers upon
43、request. 4If required, Section 7 of SAE J2429 provides an expanded discussion of the question of calibration in the case of more complex but conceptually parallel measuring system. 5If required, Section 7 of J2429 provides example possibilities for a more complex, but related measuring system. SAE J
44、2705 Revised NOV2012 Page 6 of 10 9. SELECTION AND PREPARATION OF TEST TIRES 9.1 Selecting the Tires for Good Comparability The purpose of the test must be carefully borne in mind when selecting test tires since tire properties depend on numerous factors besides the tire design and materials. It is
45、especially important to properly account for storage history (SAE 810066) and previous work history (SAE 770870). Due to the many complex questions that the test defined in this document may be used to address, specific tire selection recommendations can only be made for the case in which different
46、tires are to be compared for design or materials effects. In that case, all test tires should be of approximately the same age, have been stored under essentially identical conditions, have experienced approximately the same exercise history, and have been sampled from production lots with similar s
47、tatistical characteristics. 9.2 Inflation Pressure The inflation pressure will significantly affect the deflection of a tire under load. Therefore the appropriate test inflation pressure must be specified by the requester and set to within 5 kPa by the testing laboratory. Because tires typically ope
48、rate at a temperature higher than that of the ambient air, operating inflation pressure is usually higher than cold inflation pressure. If the purpose of testing is to simulate the running state, then the inflation pressure used in the test must be equivalent to the on-road operating inflation press
49、ure. 9.3 Tire Preparation Clean the tire surface of dirt, loose material, or other contaminants. Mount the test tire on the tire and rim standards organization specified rim.6For rim wheels used on large vehicles such as trucks, tractors, buses, and off-road machines, mounting and demounting shall be done in accordance with the practices specified in OSHA 1910.177. OSHA 1910.177 does not apply to the servicing
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