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 ther
2、efrom, 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 2017 SAE International All rights reserved. No part of this
3、publication 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: +1 724-776-49
4、70 (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:/standards.sae.org/J2718_201709 SURFACE VEHICLE RECOMMENDED PRACTICE J2718 SEP2017 Issued 2006-02 Reaffirmed 2010
5、-09 Revised 2017-09 Superseding J2718 SEP2010 Test for Tire Quasi-Static Longitudinal Force versus Longitudinal Displacement and Quasi-Static Lateral Force versus Lateral Force RATIONALE The document was edited to remove time-sensitive statements regarding pending research related to the influence o
6、f wheel stiffness. 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 i
7、s properly 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 predic
8、ting 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 Two closely related procedures are applied. In each procedure, the contact center of a loaded tire on a locked
9、 spindle 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 displ
10、acement is purely 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 thi
11、s document. The test machine must be capable of accommodating the tire sizes to be tested. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply.
12、 SAE INTERNATIONAL J2718 SEP2017 Page 2 of 8 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 +1 724-776-4970 (outside USA), www.sae.org. SAE J2047 Tire Performance Technology SAE J2429 Free-Rolli
13、ng Cornering Test for Truck and Bus Tires SAE 770870 The Effect of Tire Break-In on Force and Moment Properties SAE 810066 The Effect of Tire Aging on Force and Moment Properties of Radial Tires 2.1.2 OSHA Publications Available from U.S. Department of Labor/OSHA, 200 Constitution Avenue, Washington
14、, DC 20210, Tel: 800-321-6742, www.osha.gov/pls/publications/pubindex.list. OSHA 1910.177 Servicing Multi-Piece and Single Piece Rim Wheels (Available in wall chart form as #TTMP-7/95) 2.1.3 ISO Publications Copies of these documents are available online at http:/webstore.ansi.org/. ISO 17025 Genera
15、l Requirements for the Competence of Testing and 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 de
16、flections are changes in the relative horizontal 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
17、source. 3.1.1 LONGITUDINAL DEFLECTION (X) The 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 th
18、e projection of the wheel center onto the road 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 condition
19、s. SAE INTERNATIONAL J2718 SEP2017 Page 3 of 8 3.4 TEST PROGRAM A Test Program is a designed experiment involving multiple tests of the type described in this practice1. 4. NOMENCLATURE Table 1 lists the symbols used in this document. For definitions not in Section 3 of this practice, please see SAE
20、 J2047. Table 1 - Symbols defined Symbol Defined Term X Longitudinal Deflection Y Lateral Deflection FX Longitudinal Force FY Lateral Force FZ Normal Force p Inflation Pressure Standard Deviation (Note Subscripts) 5. LABORATORY QUALITY SYSTEM REQUIREMENT The laboratory performing the procedure speci
21、fied 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, specifically called out within this practice. 6. APPARATUS The required apparatus
22、 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 roadway, and the space housing the machine, which shall be maintained at 22 C 2 C. 6.
23、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 within 1.0% of the test machines full-scale normal force range. The machines full-
24、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 the wheel spindle2. The unintended relative shear motion between the hub and road
25、way at highest applied shear force shall be 2% or less of total shear displacement existing at the displacement limit defined in the next paragraph. The system shall be capable of generating longitudinal and lateral shear displacements between the wheel center and the contact center. This may be don
26、e by translating the hub parallel to the SAE X and Y axes or by translating the simulated roadway parallel to 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. 1 There are many
27、experimental possibilities: repeated tests 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. 2 This freedom from substantial rotation (less than
28、 0.1 at the highest applied longitudinal force) may be obtained 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. SAE INTERNATIONAL J2718 SEP2017 Page 4 of 8 6.1.2 Measuring System The system shall m
29、easure normal force (FZ) to within 0.5% of the test machines full-scale normal force range, 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)
30、within 0.5 mm, and longitudinal displacement (Y) within 0.5 mm. The system shall have 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 l
31、oose materials and deposits. It shall be coated with a 120-Grit abrasive material. The 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 te
32、st. 6.1.3.2 The roadway and its supporting structure shall be sufficiently rigid so as 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 s
33、o as to not cause the machine to be unable to satisfy the requirements of 6.1.1 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
34、 standards association, for example, the Tire and Rim Association, Inc. NOTE: Wheel stiffness may have a discernable influence on the results. 7. CALIBRATION4 Calibrate all measuring system components in accordance with the mandates of the written plan required by the laboratory quality system refer
35、enced in Section 5. Calibration must exercise all measuring system components over substantially 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 Institu
36、te of Standards and Technology or the appropriate national standards organization in 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 wh
37、en the systems calibration is performed. Gains, offsets, and other pertinent performance 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. 8. PREPARATION OF APPARATUS Prepara
38、tion of the apparatus shall ensure that the test equipment meets its calibration at the outset 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 sys
39、tem of the laboratory. The results of process control experiments shall be available to test requesters. 3 Should the measuring system sense multiple forces and moments, the output shall be corrected for load cell interaction by a matrix method conceptually equivalent to that discussed in SAE J2429.
40、 4 If 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. SAE INTERNATIONAL J2718 SEP2017 Page 5 of 8 9. SELECTION AND PREPARATION OF TES
41、T 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 important to properly account for storage history (SAE 810
42、066) 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 compared for design or materials effects. In that cas
43、e, 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 characteristics. 9.2 Inflation Pressure The inflation pres
44、sure 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 than that of the ambient air, operating inflation
45、 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 Clean the tire surface of dirt, loose material, or o
46、ther contaminants. Mount the test tire on the tire and rim standards organization specified rim5. For 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 1
47、910.177) 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 6.2. 9.4 Sample Size Typically, a single tire selected at random from among the gro
48、up of tires in each specification is an adequate sample if the goal is parametric data for producing a tire model. However, should the desire be to determine differences between tire specifications at a stated level of accuracy it will be necessary to use statistically valid sample sizes and to empl
49、oy appropriate statistical analyses of the results to define the differences among specifications. 10. TEST PROCEDURES The two procedures differ only in terms of the direction of relative displacement and the force and displacement components which are reported using a particular procedure. 10.1 Prior to Performing the Procedures The test tire and wheel assembly with the tire properly inflated and
