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 1994 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICESubmitted for recognition as an American National Sta
4、ndardJ1883REAF.OCT94Issued 1988-03Reaffirmed 1994-10Superseding J1883 MAR88ELASTOMERIC BUSHING “TRAC“ APPLICATION CODEForewordThis Reaffirmed Document has been changed only to reflect the new SAE Technical Standards BoardFormat.Elastomeric bushing life from different machines has resulted in signifi
5、cant data variations.The designs of the test machines include differing approaches to creating similar geometric environments.When examined closely, these differing approaches actually affect the environment of the test specimen.The “TRAC“ code was developed to separate the axes of this environment,
6、 so that each may be examined anddiscussed individually.The acronym “TRAC“ is derived from the labels of the most commonly discussed bushing axes: Torsional RadialAxial Conical.1. ScopeThe bushing “TRAC“ code is intended to be a tool that will aid in the definition of the geometricenvironment for th
7、e test, or use, of an elastomeric bushing.2. ReferenceThere are no referenced publications specified herein.3. Test AxesSince radial load and torsional rotation are the most commonly controlled input quantities to abushing, they are usually the principal determinants of axis orientation. (See Figure
8、 1).a. RadialThe translational axis on which the radial load is applied (by definition).b. AxialThe translational axis coinciding with the bushing inner and outer sleeve axes.c. NormalThe translational axis perpendicular to both the radial and axial axes.d. TorsionalThe rotational axis coinciding wi
9、th the axial axis.e. Conical (1st group)The rotational axis coinciding with the normal axis.f. Conical (2nd group)The rotational axis coinciding with the radial axis.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1883 Reaffirmed OCT94-2-FIGURE 1AXIS KEYC
10、OPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1883 Reaffirmed OCT94-3-4. Mode4.1 F = ForceA force being exerted along an axis.Typical examples:a. A force exerted by an air cylinder.b. The force exerted by a spring supported in a stationary manner at the
11、other end, and with a preloadrelatively high compared to its rate.c. The force exerted by a hanging weight.d. The force exerted by a servo-hydraulic actuator operating in load control.4.2 DisplacementA controlled deflection of the specimen, whether fixed in a stationary position or time variant.Typi
12、cal Examples:a. The displacement caused by a rotating eccentric or cam.b. The displacement caused by a servo-hydraulic actuator being operated in displacement control.c. The displacement (or lack of) caused by securely holding a portion of the specimen in a fixed location.NOTEAn immobilized (fixed)
13、axis has not been readily perceived as being in displacement mode.4.3 UnrestrainedThe specimen may move freely without restriction.5. Programa. K = Time InvariantThe condition that exists when the restrained (or unrestrained) portion of thespecimen is subjected to a force or displacement that remain
14、s constant in time.Typical examples:1. The exerted force is caused by a hanging weight or a cylinder maintained at constant pressure.2. The displacement is maintained in a fixed location, that is, by stationary fixturing.3. The specimen is unrestrainedthe force remains zero at all times.b. 2 = Const
15、ant Amplitude CyclingWhen the specimen is subjected to a time varying force ordisplacement where amplitude of each peak and valley (usually a sine function) is the same as theprevious one.c. 3 = Block CyclingThe same as constant amplitude cycling except that the amplitude and/orfrequency is changed
16、after a specified quantity of cycles. There may be any number of blocks in a testprogram.d. 4 = Real Time HistoryThe load or displacement history is identical to that of one which has occurredduring some actual event history. This history would include the amplitudes, order, and frequencies ofthe or
17、iginal events.e. 5 = RandomA load or displacement history, where the amplitudes, order, and frequencies occurnonperiodically.f. 6 = MatrixA load or displacement history in which the event information is tabulated in the matrixformat. In this form, the order and frequency of the events are lost.g. 7
18、= ImpactThe sudden application and removal of a load or displacement.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1883 Reaffirmed OCT94-4-h. M = CombinationAny combination of the previous.i. Y = Cross CoupledThe condition that exists when the load or d
19、isplacement of one axis (usually byintent) affects the load or displacement of another axis.6. Input InterfaceThe interface is that into which the stated input is induced.I = InnerO = OuterC = CombinationFrequently, both interfaces are constructed where neither may be selected as the onebeing activa
20、ted.7. Discussion7.1 Normal Forces Created by Torsional Rate of the BushingTorsional stressing of the elastomer bushingresults in a force couple. In a system (test machine), one sleeve is prevented from following the rotationaloscillations of the other by means of a moment arm attached to one of the
21、 sleeves. The most evident force ofthe force couple is at the reaction point (Faopposite end from the sleeve) of this moment arm. Usually notconsidered is a normal force acting through the rotation axis (Fb). This force is directly proportional to thebushing torsional (spring) rate multiplied by the
22、 angle of rotation and inversely proportional to the moment arm(Dalength) of the rotation restraint force. (See Figure 2). FIGURE 2FORCE COUPLE8. Design IntentMany factors may affect the actual performance of the designed environment of a suspensionbushing. Some may or may not be considered during t
23、he classification of this environment.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1883 Reaffirmed OCT94-5-8.1 Factors Not Included in This Classification8.1.1 BEARING CONDITIONBearings that have been worn or sloppy may change the bushing environment t
24、osomething other than original intent.8.1.2 SEAL CHARACTERISTICSLinear actuators (that is, pneumatic cylinders) have differing “break away“characteristics between the piston and bore when subjected to torsional forces.8.2 Factors Affecting Classification8.2.1 CROSS COUPLINGEffects that are present,
25、but often overlooked, during design conception.8.2.2 PREVIOUSLY NOT CONSIDEREDEffects that are present, but no effort to relate to them was expended.9. Existing Machine Concepts9.1 Clevite Test MachineSee Figure 3.FIGURE 3CLEVITE TEST MACHINE9.1.T Torsional T(D20)(D_)The displacement of the oscillat
26、ion is fixed by the unchanging lengths and geometry of the crank throws ofthe driving eccentric and driven crank.(_2_)The oscillating motion is generated by a rod connecting the crank arm of a constant angular velocity,electric motor driven shaft, to another crank arm driving a second shaft supporte
27、d with pillow blocks. Thisis a constant amplitude, constant frequency motion.(_O)This second shaft is attached to a clevis which securely clamps to the outer sleeve of the test samplebushing, forcing this outer sleeve to rotate about the axis of the bushing.COPYRIGHT Society of Automotive Engineers,
28、 Inc.Licensed by Information Handling ServicesSAE J1883 Reaffirmed OCT94-6-9.1R Radial R(FKI/FYI)(F_/_)The force generated by a dead weight is transmitted (and multiplied) along the principal radial axis througha lever and link system.(_K_/_)The dead weight generates a constant (time invariant) forc
29、e. A spring between the end of the lever and theweight minimizes any inertial forces that may be generated by lever motion.(_I/_)The principal radial load (defined by this code) is induced into the inner sleeve of the sample bushing.(_/F_)A force generated by the bushing torsional rate is induced in
30、to the normal (to the principal) to the radialaxis by the “other“ force of the couple moment (as described in 7.1).(_/_Y_)Since this force is generated by the torsional rate of the bushing, as described in 7.1, and not by anydirectly induced by mechanical design of the system, it is induced by cross
31、 coupling.(_/_I)This normal force is induced into the inner sleeve of the sample bushing.9.1A Axial A(DKC)(D_)Since a line joint (bolt through a hole) is assumed at the interface of the lever and link, the inner sleeve ofthe sample bushing is prevented from moving along its axis, and is considered a
32、s completely restrained.(_K_)The restrained condition is continuous (time invariant).(_C)This restraint results from a combination of fixturing that includes both sleeves.9.1C Conical C(DKC/DKC)(D_/_)The principal radial axis (along the input radial force) is along the link. The lower end of the lin
33、k isrestrained from any horizontal motion; by the lever fulcrum in the fore-aft direction and the line joint (boltthrough a hole) in the lateral direction. This geometry prevents any motion about the normal axis.(_K_/_)This restraint is continuous (time invariant).(_C/_)This restraint results from a
34、 combination of fixturing that includes both sleeves.(_/D_)Rotation about the radial axis is prevented by the line joint (bolt through hole) at the intersection of the leverand the link, resulting in no angular displacement.(_/_K_)This restraint is continuous (time invariant).COPYRIGHT Society of Au
35、tomotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1883 Reaffirmed OCT94-7-(_/_C)This restraint results from a combination of fixturing that includes both sleeves.9.2 Low Test MachineSee Figure 4.9.2T Torsional T(D2I)(D_)The displacement of the oscillation is fixed by the unchangi
36、ng lengths and geometry of the crank throws ofthe driving eccentric and driven crank.(_2_)The oscillating motion is generated by a rod connecting the crank arm of a constant angular velocity,electric motor driven shaft, to another crank arm driving a second shaft supported with pillow blocks. Thisis
37、 a constant amplitude, constant frequency motion.(_I)This second shaft is attached to the inner sleeve and forces it to rotate about its fixed axis.FIGURE 4LOW TEST MACHINE9.2R Radial R(FKO/FYO)(F_/_)The force generated by a dead weight is transmitted (and multiplied) along the principal radial axis
38、 througha lever and link system.(_K_/_)The dead weight generates a constant (time invariant) force. A spring between the end of the lever and theweight minimizes any inertial forces that may be generated by lever motion.(_O/_)The principal radial load (defined by this code) is induced into the outer
39、 sleeve of the sample bushing.(_/F_)A force generated by the bushing torsional rate is induced into the normal to the radial axis by the “other“force of the couple moment (as described in 7.1).COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1883 Reaffirme
40、d OCT94-8-(_/_Y_)Since this force is generated by the torsional rate of the bushing, as described in 7.1, and not directlyinduced by mechanical design of the system (that is, link length), it is cross coupled.(_/_O)This normal force is induced in the outer sleeve of the sample bushing.9.2A Axial A(D
41、KO)(D_)Since a line joint (bolt through a hole) is assumed to be at the interface of the lever and link, the innersleeve of the sample bushing is prevented from moving along its axis and is considered as beingcompletely restrained.(_K_)The restrained condition is continuously (time invariant) existe
42、nt.(_O)This restraint is created at the outer sleeve of the sample bushing.9.2C Conical C(DKC/DKC)(D_/_)The principal radial axis (along the input radial force) is along the link. The lower end of the link isrestrained from any horizontal motion by the lever fulcrum in the fore-aft direction, and th
43、e line joint (boltthrough hole) in the lateral direction. This geometry prevents any motion about the normal axis.(_K_/_)This restraint is continuous (time invariant).(_C/_)This restraint results from a combination of fixturing that includes both sleeves.(_/D_)Rotation about the radial axis is preve
44、nted by the line joint (bolt through hole) at the intersection of the leverand the link, resulting in no angular displacement.(_/_K_)This restraint is continuous (time invariant).(_/_C)This restraint results from a combination of fixturing that includes both sleeves.COPYRIGHT Society of Automotive E
45、ngineers, Inc.Licensed by Information Handling ServicesSAE J1883 Reaffirmed OCT94-9-9.3 Wahl Joint Test MachineSee Figure 5.FIGURE 5WAHL JOINT TEST MACHINE9.3T Torsional T(D2I)(D_)The displacement of the oscillation is fixed by the unchanging lengths and geometry of the crank throws ofthe driving ec
46、centric and driven crank.(_2_)The oscillating motion is generated by a rod connecting the crank arm of a constant angular velocity,electric motor driven shaft, to another crank arm driving a second shaft supported with pillow blocks. Thisis a constant amplitude, constant frequency motion.(_I)This se
47、cond shaft is attached to the inner sleeve and forces it to rotate about its fixed axis.9.3R Radial R(FKO/FMO)(F_/_)A force is imparted to the principal radial axis by a pneumatic cylinder. It is proportional to the air pressurebehind the piston. Piston seal friction is either neglected or compensat
48、ed for by adjusting the air pressureaccording to the load cell indication of actual imparted force.(_K_/_)The constant (time invariant) air pressure maintains a constant force.An optional mode of machine operation permits this load to be cycled (code entry would then be “_2_/_“).COPYRIGHT Society of
49、 Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J1883 Reaffirmed OCT94-10-(_O/_)The principal (defined by this code) radial load is induced into the outer sleeve of the sample bushing.(_/F_)A force is imparted to the normal axis by a pneumatic cylinder. It is proportional to the air pressure behindthe piston. Piston seal friction is either neglected or compensated for by air pressure adjustment.(_
