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 entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, 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.QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243TO PLACE A DOCUMENT
3、 ORDER; (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1993 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICEAn American National StandardJ1636ISSUEDFEB93Issued 1
4、993-02RECOMMENDED GUIDELINES FOR LOAD/DEFORMATION TESTING OF ELASTOMERIC COMPONENTSForewordThese guidelines describe:a. The basic behavior of elastomeric components subject to changing loads or deformationsb. Definition of a test method to meet specific requirements and a set of definitions and term
5、inology toallow interchange of information on a common basisc. Important considerations in the evaluation and reporting of test information1. ScopeThe purpose of this SAE Recommended Practice is to review factors that influence the behavior ofelastomeric components under conditions of loading or def
6、orming at a constant rate and to provide guidanceconcerning test procedures used to define or specify the load/deformation characteristics of elastomericcomponents. This characteristic is referred to as Static Stiffness. This is also referred to as a “StaticDeflection Test.“2. References2.1 Applicab
7、le PublicationThe following publication forms a part of this specification to the extent specifiedherein. The latest issue of SAE publications shall apply.2.1.1 SAE PUBLICATIONAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.SAE J1883 MAR88Elastomeric Bushing “TRAC“ Application
8、Code3. Elastomeric BehaviorAn elastomer is a viscoelastic material. It acts as though it were composed of anelastic component and a viscous component. The elastic component controls stress versus strain behavior.Because of an elastomers viscoelastic nature, the dynamic response and mechanical behavi
9、or are dependentupon stress or strain history, rate of deformation, level of strain, and specimen temperature.4. Specimen HistoryPrior to testing it is important to know if the component has experienced any mechanicalpreflexing or temperature changes and to know the timing of these influences. This
10、is necessary forconsistency in comparing test results.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1636 Issued FEB93-2-4.1 Mechanical PreflexingIt is well known that elastomers undergoing load/deformation tests will progressivelychange for up to the fi
11、rst 1000 cycles until a steady-state condition is reached. Depending on the elastomer,this change ranges from about 3 to 25%. It is also known that most of the stiffness on the first cycle can beregained if a period of about 8 h or more elapses between load deflection tests. Consequently, preflexing
12、influences must be considered. For preflexing to be effective, the load and/or deflection must be at least that atwhich the stiffness is to be determined.4.2 Temperature ChangesSince elastomers are viscoelastic materials, it is necessary to know the temperatureof the specimen and its temperature his
13、tory prior to testing. Storing a specimen in a very cold or hotatmosphere prior to testing will influence the static data in mechanical testing as well as the time to wait beforeregaining the first static data after preflexing.4.3 AgingAssembled components require sufficient time for the elastomeric
14、 material to integrate effects such asassembly oil or precompression. One week is recommended. Oven aging for 3 h at 70 C is sometimes usedas a substitute for natural aging. This serves to yield more uniform results.5. Test SetupThe type and manner of fixturing a component for evaluation greatly aff
15、ects the validity of themeasured data. The geometry and loading procedure for each fixture should be clearly specified.5.1 AxialThe test fixture must maintain any predefined relationship between the source of loading ordeformation and the component under test during the entire test sequence.5.2 Rota
16、tionalFor evaluation of components in rotational modes (i.e., torsional or conical) it will be necessary tospecify the mode of loading as rotational with a torque and center of rotation (provides rotation input only) orlinear with a force and lever arm (provides rotation and translational inputs). C
17、are should be taken to maintainthe predefined geometrical relationships between the fixturing and the component under test during the entiretest sequence. Please refer to SAE J1883 for assistance in the definition of the geometric environment for anyparticular test.6. Test SequenceEach test typicall
18、y consists of a pretest period and a test period.The pretest period is used to apply a preload level and cyclic loads or displacements to the specimen prior todata acquisition. During the pretest period, ramp to the preload level, perform precycles, ramp back to thepreload level, and then maintain t
19、he preload level for a hold period. Each precycle consists of a ramp toPrecycle Level 1 followed by a ramp to Precycle Level 2.The test period is used for data acquisition. From the preload level, ramp to Test Level 1 to Test Level 2 andback to Test Level 1. Typically, data is acquired from Test Lev
20、el 1 to Test Level 2 then back to Test Level 1.(See Figure 1.)FIGURE 1SIMPLIFIED TEST LAYOUTCOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1636 Issued FEB93-3-The following must be defined for each Load/Deformation test sequence. Input parameters should
21、relate tospecific applications. The test must be fully defined to ensure repeatability and consistency of results.6.1 Precycle Parametersa. Number of precyclesb. Preloadc. Rate mode (load or displacement)d. Precycle ramp ratee. Precycle level 1 and level 26.2 Holda. Length of hold6.3 Test Cyclea. Ra
22、te mode (load or displacement)b. Test ramp ratec. Test level 1 and level 2d. Calculation technique (See Section 8)e. Direction of loading during measurement (ascending or descending) or average of ascending anddescendingf. Analysis point(s)By definition, level 1 is the first level that is achieved.
23、It may be higher or lower than the preload level.Ascending data is defined to be from test level 1 to test level 2 to avoid confusion concerning the sequence ofdata collection. For example, it could be confusing to define the end levels as higher or lower (is 500 N higherthan 300 N?).7. Calculation
24、TechniquesStatic Stiffness can be calculated in many ways. Static Stiffness can be associatedwith a segment of time (Kchord analysis method) or with a point in time (Ktan Analysis Method). Static Stiffnesscan also be measured during the ascending or descending portion of the test or averaged between
25、 the two. Analternative to calculating stiffness is to measure the change in load or displacement (Delta(load) or Delta(disp)resulting from an imposed displacement or load, respectively.7.1 Kchord Analysis MethodThe Kchord analysis method is the stiffness associated with a segment of time. It iscalc
26、ulated by dividing the specimens change in load by its change in displacement for the selected segment.(See Equation 1.)(Eq. 1)When the averaging technique is used with the Kchord analysis method, the calculation averages the ascendingsegment and corresponding descending segment in the calculations.
27、 (See Figures 2 and 3.)KchordDeltaload)(Deltadisp()-=COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1636 Issued FEB93-4-FIGURE 2Kchord ANALYSIS METHOD WITHOUT AVERAGINGFIGURE 3Kchord ANALYSIS METHOD WITH AVERAGING7.2 Ktan Analysis MethodThe Ktan analysis
28、 method determines the instantaneous stiffness of the specimen -the stiffness at a selected point. One accepted method is to perform a second-order least squares curve fitthrough the selected point, and through points adjacent to both sides of the selected point. Typically, 10% ofthe total points ac
29、quired are used, i.e., 5% of each side of the selected point.Calculations are based on equation 2:(Eq. 2)where:x represents displacement valuesy represents load valuesA,B,C are coefficients determined in the second-order regressionThis calculation yields a second-order line that has the best fit thr
30、ough these points. The stiffness is thencalculated as the slope of the second-order line at the selected point, based on equation 3:(Eq. 3)yAx2 BxC+=Ktandydx- 2AxB+=COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1636 Issued FEB93-5-When the averaging tec
31、hnique is used with the Ktan analysis method, the calculation averages the ascendingdata point and corresponding descending data point in the calculations. (See Figures 4 and 5.)FIGURE 4Ktan ANALYSIS METHOD WITHOUT AVERAGINGFIGURE 5Ktan ANALYSIS METHOD WITH AVERAGING7.3 Delta Analysis Method7.3.1 De
32、lta(load) analysis method determines the specimen change in load as the result of an applieddisplacement. (See Figures 6 and 7.)FIGURE 6DELTA(load) ANALYSIS METHOD WITHOUT AVERAGINGCOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1636 Issued FEB93-6-FIGURE
33、 7DELTA(load) ANALYSIS METHOD WITH AVERAGING7.3.2 Delta(disp) analysis method determines the specimen change in displacement as the result of an appliedload. (See Figures 8 and 9.)FIGURE 8DELTA(disp) ANALYSIS METHOD WITHOUT AVERAGINGFIGURE 9DELTA(disp) ANALYSIS METHOD WITH AVERAGINGCOPYRIGHT Society
34、 of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1636 Issued FEB93-7-8. Evaluation and Reporting of Test DataAs with calculation techniques, there are many commonly usedformats for evaluation and reporting of data including tabular and graphical presentation. The key is co
35、mpletedocumentation of the test conditions and data presentation. Figure 10A.8.1 Sign ConventionCompression has traditionally been represented as positive values in this test but asnegative values in other applications. The sign convention should be clearly stated on all test results.8.2 Zero Refere
36、nce OffsetTraditionally, the zero reference point of the load and displacement values have beenset at the preload level prior to data acquisition as opposed to a no-load level. The zero reference point shouldbe clearly stated on all test results.8.3 Data Analysis PointsMany available techniques give
37、 alternatives for data analysis. The technique usedand data points included in the evaluation should be clearly indicated on all results.FIGURE 10AEVALUATION AND REPORTING OF TEST DATACOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1636 Issued FEB93-8-FIG
38、URE 10BEVALUATION AND REPORTING OF TEST DATA (CONTINUED)PREPARED BY THE SAE VIBRATION COMMITTEECOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1636 Issued FEB93RationaleNot applicable.Relationship of SAE Standard to ISO StandardNot applicable.ApplicationT
39、he purpose of this SAE Recommended Practice is to review factors that influence the behaviorof elastomeric components under conditions of loading or deforming at a constant rate and to provideguidance concerning test procedures used to define or specify the load/deformation characteristics ofelastom
40、eric components. This characteristic is referred to as Static Stiffness. This is also referred to asa “Static Deflection Test.“Reference SectionSAE J1883 MAR88Elastomeric Bushing “TRAC“ Application CodeDeveloped by the SAE Vibration CommitteeCOPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling Services
