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 reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2006 SAE International All rights reserved. No part of this publication m
3、ay 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: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: custsvcsae.org SAE WEB ADDRESS: http:/www.sae.org J2718 ISSUED FEB2006 SURFACE VEHICLE RECOMMENDED PRACTICE Issued 2006-02 Test for Tire Quasi-Static Longitudinal Force vs. Longitudinal Displacement and Quasi-Static Lateral Force vs. Lateral Displacement RATIONALE This Reco
5、mmended Practice 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 loads given the road surface profile from a single set of experimental results, thus, eliminating duplicat
6、e testing. 1. SCOPE This SAE Recommended Practice describes application of two closely related test procedures, which together determine the linear range longitudinal and lateral stiffnesses of a statically loaded non-rotating tire. The procedures apply to any tire so long as the equipment is proper
7、ly sized to correctly conduct the measurements for the intended test tire. The data are suitable for use in determining parameters for road load models and for comparative evaluations of the measured properties in research and development. NOTE: Herein, road load models are models for predicting for
8、ces 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 Two closely related procedures are applied. In each procedure the contact center of a loaded tire on a locked spindle
9、and its wheel center are displaced horizontally one with respect to the other so as to generate shear force versus shear deflection data. In the first procedure the displacement is purely longitudinal, parallel to the X-axis in the SAE Tire Axis System. In the second procedure the displacement is pu
10、rely lateral, parallel to the Y-axis in the SAE Tire Axis System. These procedures are spelled out in the body of this document. 1.2 Test Machines This document is test machine neutral. It may be applied using any type of test machine capable of fulfilling the requirements stated in this document. T
11、he test machine must be capable of accommodating the tire sizes to be tested. 2. REFERENCES 2.1 Applicable Publications The following publications form part of the specification to the extent specified herein. Unless otherwise indicated the latest revisions of all publications shall apply. Copyright
12、 SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2718 Issued FEB2006 - 2 - 2.1.1 SAE Publications Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and C
13、anada) or 724-776-4970 (outside USA), www.sae.org. SAE J2047 Tire Performance Technology SAE J2429 Free-Rolling Cornering Test for Truck and Bus Tires 2.1.2 OSHA Publication Available from Rubber Manufacturers Association, 1400 K Street, NW, Suite 900, Washington, DC 20005, Tel: 202-682-4800, www.rm
14、a.org. OSHA 1910.177 Servicing Multi-Piece and Single Piece Rim Wheels (Available in wall chart form as #TTMP-7/95) 2.1.3 ISO Publication Available from ANSI, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org. ISO 17025 General requirements for the competence of testing a
15、nd calibration laboratories 3. DEFINITIONS The definitions that follow are of special meaning in this document and are either not contained in other Recommended Practices or are worded somewhat differently in this practice. 3.1 Shear Deflections Shear deflections are changes in the relative horizont
16、al position between the contact center and the projection of the wheel center onto the road plane. Deflections may arise either due to horizontal translation of the contact center or the wheel center or both. They are considered equivalent regardless of source. 3.1.1 Longitudinal Deflection (X) The
17、relative horizontal position between the contact center and the projection of the wheel center onto the road plane is changed only parallel to the SAE X-axis. 3.1.2 Lateral Deflection (Y) The relative horizontal position between the contact center and the projection of the wheel center onto the road
18、 plane is changed only parallel to the SAE Y-axis. 3.2 100% Load 100% load is the test requester specified reference load. 3.3 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. Copyright SAE International Provided by IHS
19、 under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2718 Issued FEB2006 - 3 - 3.4 Test Program A Test Program is a designed experiment involving multiple tests of the type described in this practice.14. NOMENCLATURE Table 1 lists the symbols
20、 used in this document. For definitions not in Section 3 of this practice please see SAE J2047. TABLE 1 SYMBOLS DEFINED Symbol Defined Term XLongitudinal Deflection YLateral Deflection FXLongitudinal Force FYLateral Force FZNormal Force p Inflation Pressure Standard Deviation (Note Subscripts) 5. LA
21、BORATORY QUALITY SYSTEM REQUIREMENT The laboratory performing the procedure specified in this document shall have a quality system either conforming to ISO 17025 or which can be shown to be functionally equivalent to ISO 17025. The elements of such a system are assumed below and are not, therefore,
22、specifically called out within this practice. 6. APPARATUS The required apparatus consists of a loading machine with the characteristics noted and test wheels. 6.1 Loading Machine The loading machine consists of a tire loading and positioning system, a measuring system, a flat surface simulated road
23、way, 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 maintain the tire with the tire/wheel plane within 0.10 of perpendicular to the simulated roadway during all loading. Loading shall produce normal forces accurate to w
24、ithin 1.0% of the test machines full-scale normal force range. The machines full-scale normal force range shall allow imposition of loads equivalent to at least three times the 100% load. During the procedures described in this document, the machines hub must be fixed with respect to rotation about
25、the wheel spindle.2The unintended relative shear motion between the hub and roadway at highest applied shear force shall be 2% or less of total shear displacement existing at the displacement limit defined in the next paragraph. 1There are many experimental possibilities: repeated tests of the same
26、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. 2This freedom from substantial rotation (less than 0.1 at the highest applied longitudinal force) may be o
27、btained either by having a spindle without a rotational degree of freedom or by providing a lock in the case of a spindle with a rotational degree of freedom. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from
28、IHS-,-,-SAE J2718 Issued FEB2006 - 4 - The system shall be capable of generating longitudinal and lateral shear displacements between the wheel center and the contact center. This may be done by translating the hub parallel to the SAE X and Y axes or by translating the simulated roadway parallel to
29、SAE X and Y axes. The system shall allow translation sufficient to reach shear force magnitudes equal to one-third of the applied normal force at three times the 100% load. 6.1.2 Measuring System The system shall measure normal force (FZ) to within 0.5% of the test machines full-scale normal force r
30、ange, lateral force (FY) to within 0.5% of the test systems full scale lateral force range, longitudinal force (FX) to within 0.5% of the test systems full scale longitudinal force range3, lateral displacement (X) within 0.5 mm, and longitudinal displacement (Y) within 0.5 mm. The system shall have
31、a normal force range that allows measurement of forces equivalent to those existing at 300% of the client specified 100% load. 6.1.3 Simulated Roadway The simulated roadway shall be a smooth flat surface, free of loose materials and deposits. It shall be coated with a 120-Grit abrasive material. The
32、 material of which the roadway itself 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 the tire footprint throughout this test. 6.1.3.2 The roadway and its supporting structure shall be sufficiently rigid so as
33、 to not change appreciably in either transverse or longitudinal orientation or in curvature under the machines maximum applied normal force. Appreciably implies that roadway deformation will be sufficiently small so as to not cause the machine to be unable to satisfy the requirements of Sections 6.1
34、.1 or 6.1.2. 6.2 Test Wheels Test wheels shall meet the dimensional tolerances of original equipment wheels supplied on new vehicles and shall have the rim profile specified for the test tire by the appropriate tire and rim standards association, for example, the Tire and Rim Association, Inc. NOTE:
35、 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 appropriately characterize wheel stiffness for use in this document. It is planned to address this question by research
36、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 laboratory quality system referenced in Section 5. Calibration must exercise all measuring system components over s
37、ubstantially their full range of application and must be performed not less than once each year. The reference standards and instruments used in measuring system calibration shall be traceable to the National Institute of Standards and Technology or the appropriate national standards organization in
38、 countries other than the United States. Calibration certificates for reference standards and instruments shall be valid at the time the system is calibrated. These must be on file in the testing laboratorys files when the systems calibration is performed. Gains, offsets, and other pertinent perform
39、ance measures and comments on system behavior during calibration shall be kept permanently on file within the testing laboratorys archives and be available to customers on request. 3Should the measuring system sense multiple forces and moments, the output shall be corrected for load cell interaction
40、 by a matrix method conceptually equivalent to that discussed in SAE J2429. 4If required, Section 7 of SAE J2429 provides an expanded discussion of the question of calibration in the case of a conceptually parallel measuring system designed to simultaneously sense three forces and two moments. Copyr
41、ight SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2718 Issued FEB2006 - 5 - 8. PREPARATION OF APPARATUS Preparation of the apparatus shall ensure that the test equipment meets its calibration at the ou
42、tset of each 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 te
43、st requesters. 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 especially importan
44、t 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 tires are to be com
45、pared 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 statistical characte
46、ristics. 9.2 Inflation Pressure The inflation pressure will significantly affect the stiffnesses of a tire. 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 operate at a temperature higher
47、 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 pressure. 9.3 Tire Preparation Cl
48、ean the tire surface of dirt, loose material, or other contaminants. Mount the test tire on the tire and rim standards organization specified rim.5For 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 of rim wheels used on automobiles or on pickup trucks or vans utilizing automobile tires or truck tires designated “LT”. The wheels used shall meet the specifications noted in Section 6.2. 9.4 Sa
