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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 therefr
2、om, 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: (412) 772-8512 FAX: (412) 776-0243 TO PLACE A DOCU
3、MENT ORDER; (412) 776-4970 FAX: (412) 776-0790 SAE WEB ADDRESS http:/www.sae.org Copyright 1990 Society of Automotive Engineers, Inc. All rights reserved.Printed in U.S.A. SURFACE VEHICLE 400 Commonwealth Drive, Warrendale, PA 15096-0001 INFORMATION REPORT J2052 REV. DEC97 Issued1990-03 Revised1997-
4、12 Superseding J2052 MAR90 (R) TEST DEVICE HEAD CONTACT DURATION ANALYSIS A technically equivalent version of SAE J2052 is included in ISO Technical Report 12351. ForewordA technique has been established for determining head impact contact duration called the “Force Difference Method.“ This techniqu
5、e allows calculation of Head Injury Criterion (HIC) only during head contact. 1.ScopeThis methodology can be used for all calculations of HIC, with all test devices having an upper neck triaxial load cell mounted rigidly to the head, and head triaxial accelerometers. 1.1PurposeThe purpose of this SA
6、E Information Report is to describe a computer-adaptable technique for determining head engagement and disengagement times for use in the calculation of the HIC without reliance on contact switches or photography. 2.References 2.1Applicable PublicationsThe following publications form a part of this
7、specification to the extent specified herein. Unless otherwise indicated, the latest version of SAE publications shall apply. 2.1.1SAE PUBLICATIONAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. SAE J211-1 MAR95Instrumentation for Impact Test 2.1.2FEDERAL PUBLICATIONAvailable f
8、rom the Superintendent of Documents, U. S. Government Printing Office, Mail Stop: SSOP, Washington, DC 20402-9320. FMVSS 49: 571-208Occupant Crash Protection, revised as of April, 1997 2.1.3ISO PUBLICATIONAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. ISO Technical Report 123
9、51Determination of head contact and duration in impact testsISO/TC22/ SC12/WG3N355 SAE J2052 Revised DEC97 -2- 3.Definitions 3.1HICThe HIC is one of the “injury criteria“ prescribed by S6 of the Federal Motor Vehicle Safety Standard (FMVSS) 208. It is the maximum value calculable from the head c.g.
10、resultant acceleration-time profile in accordance with Equation 1: (Eq. 1) where: a is the resultant acceleration expressed as multiples of G (the acceleration of gravity), and t1 and t2 are any two points in time during the crash. NOTEAlthough a HIC window of 36 milliseconds maximum was subsequentl
11、y mandated by NHTSA, it is not utilized with this document. 3.2Contact HICHIC values calculated only during the periods of each head contact. 3.3te, tdThe head engagement and disengagement times, te and td respectively, are determined by the method given in Section 5. These are the starting and endi
12、ng times, i.e., the windows for the iterative HIC calculations for each head contact. NOTEThe maximum contact HIC for each te, td interval will have associated with it times t1, t2 which may be equal to, or less than the te, td interval. 3.4Accelerometers (ax, ay, az)The triaxial accelerometer(s) in
13、 the head of the test device will be referred to as an accelerometer, omitting the triaxial classification as defined in SAE J211-1; +ax is forward, +ay is to the right, and +az is downward. These orientations are shown in Figure 1. 3.5Load CellThe triaxial force load cell (attached rigidly to the b
14、ase of the skull portion of the test device to which the neck is attached) will be referred to as a load cell, omitting the triaxial and upper neck classification. Load cells with additional outputs can also be used. 3.6Head Mass (M)The mass of the head including the masses of the head accelerometer
15、s and mounting brackets and the mass of the load cell above the gage plane. NOTECaution should be exercised to minimize the effect of elements external to the neck, such as neck skins or wires, which might carry load or modify the head mass. 3.7Inertial Head Forces (Max, May, Maz)The inertial head f
16、orces are calculated from the triaxial accelerometers which are inside the head of the test device. The accelerations are multiplied by the M of the test device to determine the inertial head forces. The directions of these inertial forces are the same as the directions of their corresponding accele
17、ration vectors. 3.8Neck Forces (Fx, Fy, Fz)The neck forces are determined directly from the load cell, per 3.5, which reads the forces acting on the neck at the location of the load cell (the base of the skull in this case). Fx is longitudinal shear, Fy is lateral shear, and Fz is axial force. Force
18、s (Fx, Fy, Fz) are applied to the neck in this paper (see Figure 1). A positive Fx output from the load cell means head rearward motion relative to neck; positive Fy output is head left motion relative to neck; and positive Fz output is tensile force or head upward motion relative to the neck. Conve
19、ntions are per SAE J211-1. HIC 1 t2t1() - - a.dt t1 t2 2.5 t2t1()= SAE J2052 Revised DEC97 -3- FIGURE 1HEAD CONTACT DURATION ANALYSISACCELERATION AND FORCE 3.9Test DeviceAny full, partial, or simulated anthropomorphic dummy equipped with head accelerometers and load cell per 3.4 and 3.5 is defined a
20、s the test device. For example, the 50th percentile male Hybrid III dummy specified in Part 571, subpart E, of FMVSS 208, can be used, as can any derivative of that dummy with proper instrumentation. 4.Data Acquisition And Processing SystemThe data acquisition and processing system must be capable o
21、f supplying transducer data per SAE J211-1 which recommends that both head acceleration and neck force utilize channel class 1000, and that any multiple recording devices are time-referenced per 4.4.2 of SAE J211-1. 5.Procedure For Determining Head Contact Duration (te, td)The subject method uses Eq
22、uation 2: (Eq. 2) The acceleration components (ax, ay, az) of the head are multiplied by the M to produce the components of inertial head force. Each neck force component (Fx, Fy, Fz) is subtracted from the corresponding calculated inertial head force component. The aforementioned subtractions produ
23、ce three force-differences. The external resultant head force (F) is calculated by taking the root sum square of the force-differences, and is plotted as a function of time. This plot represents the resultant contact force acting on the head. In order to establish consistent engagement (te) and dise
24、ngagement (td) times for each contact, the following method is established: A contact is assumed to have occurred when the force level has reached 500 N. The te for this contact is obtained by tracing backwards in time from the 500 N point on the force versus time curve until 200 N is first reached.
25、 The td for this contact is determined by tracking forward in time until the curve crosses the 200 N force level. A subsequent contact is assumed to have occurred when the force level again has reached 500 N after the first time td. The te and td for this second contact are determined in the same ma
26、nner used for determining te and td in the previous contact. This process is repeated for each subsequent contact, and is illustrated in Figure 2. FMaxFx()2MayFy()2MazFz()2+= SAE J2052 Revised DEC97 -4- FIGURE 2DETERMINATION OF CONTACT DURATIONS FROM CONTACT FORCE-TIME CURVE 6.Other Information 6.1M
27、aximum Contact HICThe HIC is calculated for each contact interval determined in Section 5. The HIC t1 and t2 values for each contact interval may be equal to, or within the corresponding te, td interval. The maximum contact HIC is the largest HIC value from all the contacts. 6.2Resultant External Co
28、ntact Force, F, and Its Direction ( x, y, z)The procedure in Section 5 allows the calculation of the actual contact force (which is the peak force shown in Figure 2). The direction of that force can be obtained by Equations 3 through 5: (Eq. 3) (Eq. 4) (Eq. 5) x 1 MaxFx F - -cos= y 1 MayFy F - -cos=
29、 z 1 MazFz F - -cos= SAE J2052 Revised DEC97 -5- where: x, y, and z are the direction cosine angles of the resultant external contact force, F. 7.Notes 7.1Marginal IndiciaThe change bar (l) located in the left margin is for the convenience of the user in locating areas where technical revisions have
30、 been made to the previous issue of the report. An (R) symbol to the left of the document title indicates a complete revision of the report. PREPARED BY THE SAE SAFETY TEST INSTRUMENTATION COMMITTEE SAE J2052 Revised DEC97 RationaleThe main changes to the document include: a.The foreword changed. b.
31、In the Reference Section, SAE J211 was changed to SAE J211-1. The number and title changed for ISO/IC22/SC12/WG3N179. c.3.6, the last part of the sentence, “which is rigidly attached to the head” was changed to “above the gage plane.” d.3.9 2nd sentence, “For example” was added e.The document was re
32、formatted to comply with the SAE Technical Standards Board format. This included making Definitions, Section 3. All other sections numbers have changed. Relationship of SAE Standard to ISO StandardA technically equivalent version of SAE J2052 is included in ISO Technical Report 12351. ApplicationThi
33、s methodolody can be used for all calculations of HIC, with all test devices having an upper neck triaxial load cell mounted rigidly to the head, and head triaxial accelerometers. Reference Section SAE J211-1 MAR95Instrumentation for Impact Test FMVSS 49: 571-208Occupant Crash Protection, revised as of April, 1997 ISO Technical Report 12351Determination of head contact and duration in impact testsISO/TC22/ SC12/WG3N355 Developed by the SAE Safety Test Instrumentation Standards Committee