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 revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2012 SAE International All rights reserved. No part of this p
3、ublication 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: +1 724-776-497
4、0 (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:/www.sae.org/technical/standards/J2238_201211SURFACE VEHICLE RECOMMENDED PRACTICE J2238 NOV2012 Issued 1994-06 Rev
5、ised 2012-11 Superseding J2238 OCT2001 Airbag Inflator Ballistic Tank Test Procedure Gas Generating Devices Used In Inflatable Restraint Systems RATIONALE Purposes of this revision to SAE J2238 are to clarify data acquisition system / instrumentation requirements for inflator tank testing, to update
6、 some the terminology used to describe inflators including some the newer systems that have been introduced since the revision to this specification. TABLE OF CONTENTS 1. SCOPE 2 2. REFERENCES 2 2.1 Applicable Documents 2 2.2 Related Publications . 3 3. DEFINITIONS: 3 4. GENERAL TEST REQUIREMENTS .
7、4 4.1 Test Facility . 4 4.2 Safety Requirements 4 4.3 Equipment List 4 5. EQUIPMENT SPECIFICATION 5 5.1 Test-Tank 5 5.2 Pressure Transducer 6 5.3 Temperature Conditioning Chamber 8 5.4 Tank or Inflator Thermocouples 8 6. TEST PROCEDURE . 8 6.1 Temperature Conditioning 8 6.2 Installation to Tank 8 6.
8、3 Time to Deployment 9 6.4 Deployment Pulse/Stimulus 9 6.5 Typical Test Sequence . 9 6.6 Tank Cleaning . 11 7. DATA REDUCTION 11 SAE J2238 Revised NOV2012 Page 2 of 28 8. ACCEPTANCE RECORDS 11 8.1 Pressure Data and Optionally Current/Voltage versus Time Plots . 11 8.2 Typical Data Reporting . 11 9.
9、NOTES 14 9.1 Marginal Indicia . 14 APPENDIX A TANK VOLUME MEASUREMENT METHOD 15 APPENDIX B TYPICAL TEST SET-UP DIAGRAM . 16 APPENDIX C DATA FILTERING TECHNIQUES 17 FIGURE 1 CLOSED TEST TANK. 6 FIGURE 2 PRESSURE TIME CURVE . 12 FIGURE 3 VOLTAGE/CURRENT TIME CURVE . 13 FIGURE B1 TYPICAL TEST SET-UP .
10、16 FIGURE C1 ACTUAL TANK TEST DATA VERSUS 100 HZ FORWARD PASS FILTERED CURVE . 18 FIGURE C2 ZOOM OF FIGURE C1 WITH 100 AND 200 HZ FORWARD PASS FILTERED CURVES . 18 FIGURE C3 ACTUAL TANK TEST DATA VERSUS 100 HZ DUAL PASS FILTERED CURVE 20 FIGURE C4 ZOOM OF FIGURE D3 WITH 100 HZ DUAL PASS FILTERED CUR
11、VE 20 FIGURE C5 ACTUAL TANK TEST DATA VERSUS 100 HZ DUAL PASS FILTERED CURVE WITH 3 PSI DELAY . 21 FIGURE C6 ZOOM OF FIGURE D5 WITH 100 HZ DUAL PASS FILTERED CURVE WITH 3 PSI DELAY . 21 FIGURE D7 FORTRAN CODE FOR IMPLEMENTING DELAYED START . 22 1. SCOPE This SAE Recommended Practice establishes a ba
12、llistic tank test procedure for evaluating inflator assemblies used in inflatable restraint systems. It is intended to be a general procedure for repetitive testing and suggests only general guidelines for the safe conduct of tests and data correlation. Uniform test requirements, test procedures, an
13、d data recording requirements are specified. The intent of the document is to provide a procedure employing a ballistic tank test method for determining the ability of an inflator to meet requirements for deploying inflatable restraint systems. A ballistic tank test is described which will yield rep
14、eatable and comparable results for evaluating a given inflator configurations pressure output versus time. Use of the ballistic tank test for comparison of various inflator technologies may be of limited value due to differences in gas temperature, gas composition and mass flow effects on airbag per
15、formance as it relates to occupant protection. 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. 2.1.1 SAE Publications Available from SAE I
16、nternational, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J211-1 Instrumentation for Impact Test - Part 1: Electronic Instrumentation SAE Paper 91080 Use and Selection of Thermocouples SAE J2238 Revised
17、NOV2012 Page 3 of 28 2.1.2 ASME Publication Available from the American Society of Mechanical Engineers, 22 Law Drive, PO Box 2900, Fairfield, NJ 07007-2900, Tel: 973-882-1170, www.asme.org. ASME Boiler and Pressure Vessel Code, Section VIII Rule for Construction of Pressure Vessels, Division 11, an
18、 American Standard 2007 Edition (please see current amendment) 2.1.3 Other Publication Langes Handbook of Chemistry, McGraw Hill, 1985 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of this SAE Technical Report. 2.2.1 SAE Pu
19、blication Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J1538 Glossary of Automotive Inflatable Restraint Systems 2.2.2 Other Publications Abernethy, R. B. and Thompson, J
20、. W., “Measurement Uncertainty Handbook,” Instrument Society of America, 1980 Stein, P. K., “The Response of Transducers to Their Environment, the Problem of Signal and Noise,” Shock and Vibration Bulletin, Vol. 40, No. 7, pp. 115, 1970 Taylor, J. L., “Computer-Based Data Acquisition Systems, Design
21、 Techniques,” Instrument Society of America, 1986 Megyesy, Eugene F., “Pressure Vessel Handbook,” Publishing, Inc., 1989 3. DEFINITIONS: Per SAE TSB 002 “Preparation of SAE Technical Reports” revised June 1992 developed by the SAE Editorial Advisory Committee. Section 9.4 of the SAE TSB 002 states:
22、“Shall” or “Should” - The use of “shall” or “should” has no bearing on the voluntary nature of SAE technical reports. Inclusion of or reference to an SAE report in a document, standard, or contract by a company or agency is a voluntary act. When a report is so cited, the report becomes a requirement
23、 within the limitations set forth by the document, standard, or contract. The following shall apply to the use of “shall” or “should” in SAE reports: Section 9.4.1 Shall - is to be used wherever the criterion for conformance with the specific recommendations requires that there shall be no deviation
24、. Its use shall not be avoided on the grounds that compliance with the report is considered voluntary. Section 9.4.2 Should is to be used wherever noncompliance with a specific recommendation is permissible. “Should” shall not be substituted for “shall” on the grounds that compliance with the report
25、 is voluntary. SAE J2238 Revised NOV2012 Page 4 of 28 4. GENERAL TEST REQUIREMENTS The ballistic tank test equipment for acceptance testing of inflators used in inflatable restraints systems shall provide a reliable, accurate, and repeatable testing system, adaptable for mounting various configurati
26、ons of inflators. The following sections will describe the general needs for the test facility equipment and safety requirements. 4.1 Test Facility Airbag inflators are typically classified by the US Department of Transportation (DOT) as a Class 9 miscellaneous hazardous material. Older inflators ma
27、y have been classified as a 1.4 explosive, Explosive Class C, Flammable Solid or Argon compressed gas nonflammable. Therefore, the facility for conducting tests on pyrotechnic or stored-gas pressure vessel devices must comply with all local and state building codes. A proper floor plan and work area
28、 design is also very important for proper execution of tests. Features include a physical barrier between test personnel and the device under test. In addition, a temperature controlled environment is important for test result accuracy, and a room exhaust fan is recommended to vent smoke and particu
29、lates from the test area. 4.2 Safety Requirements In consideration of safety for test personnel working with experimental devices, appropriate facility and proper personal protective equipment must be provided. Examples of this equipment include remote firing capability, warning system (e.g., siren
30、and/or light) shielding, flame-retardant lab coats, electrostatic ground straps, safety glasses, hearing protection, respirators, and gloves as required. Proper written safety procedures and check lists should be followed in accordance with industry practice. All applicable OSHA safety standards mus
31、t be followed. 4.3 Equipment List The equipment will typically consist of the following basic components: Item Equipment Description A Test-Tank Contains the generated gas B Pressure Transducer(s) Measures pressures inside the tank or inflator C Transducer Signal Conditioning Provides transducer pow
32、er and amplification as needed by the data acquisition system (may be integral part of data acquisition system) D Data Acquisition System Records and displays pressure, temperature, voltage, current, etc., all versus time from an inflator test E Temperature Conditioning Chamber Conditions inflator t
33、o desired deployment temperature F Thermocouple(s) Measures gas temperature inside the tank, tank wall or on the inflator surface (all optional) G Firing Source Provides the proper stimulus to actuate the inflator H Current monitor(s) Measures current applied to an electrical initiator (2 required f
34、or dual level inflators) I Voltage monitor(s) Measures voltage applied to an electrical initiator (optional) (2 required for dual level inflators) Section 4 of this procedure will discuss the equipment specifications typically used. SAE J2238 Revised NOV2012 Page 5 of 28 5. EQUIPMENT SPECIFICATION T
35、he ballistic tank test facility shall consist of equipment meeting the following specifications. 5.1 Test-Tank A test-tank shall be provided for containing an inflators pressure output over the anticipated pressure and temperature range. The test-tank construction should conform to the ASME Code for
36、 Pressure Vessels Section VIll Division 2. A tank shape with a hemispherical end is preferred to facilitate tank washing. The test-tank shall be secured and of such design that no movement or distortion of the test-tank results upon deployment of the inflator. 5.1.1 Tank Volume The volume of the tes
37、t-tank to be used for a particular inflator is determined based on the inflators design output as follows: Inflator Application Typical Test-tank Volumes (Liters) Driver-Side 28.3 0.3 or 60.0 0.6 Passenger-Side, Pedestrian-Protection, or Occupant-to-Occupant 60.0 0.6 Side-Impact, Roll-Over, Knee, Ac
38、tive Knee Bolster, Active Side Bolsters, or Inflatable Seat Belt 28.3 0.3 or 10. 0.1 a. If different tank volumes exist, a method of correlation of the tank to pressure data is required; i.e., test a statistically significant number of samples in each tank and compare values. b. For other applicatio
39、ns such as pretensioners, hypertensioners, headrest, foot, or roof applications, the volume selected should be near the specific application volume or new tank volumes should be developed. c. Tank volume shall be measured. A recommended procedure is outlined in Appendix A. 5.1.2 Inflator Orientation
40、/Sealing The inflator should be positioned in the test-tank to the extent as possible such that the exhaust-gases from the inflator do not impinge on pressure transducer ports. The test-tank must provide adequate sealing such that pressure is contained within the tank during deployment of the inflat
41、or. An exception is for vented tank-tests where vents of a pre-defined size may be present to allow controlled venting during deployment. 5.1.3 Tank Surface Finish The inside surfaces of the test-tank shall be smooth to facilitate cleaning and tank washing. A finish of equal to or better than 32 m f
42、inish is recommended. Coatings may be used to facilitate tank wash; however, caution should be used in coatings that may wear off or otherwise exhibit deterioration. 5.1.4 Tank Configuration The test-tank shall provide a means to rigidly mount the inflator to the tank without restricting the flow of
43、 gas into the tank. Figure 1 depicts one type of test tank used in the airbag industry. Other shapes are acceptable; however, a correlation between different shape tanks may be required. SAE J2238 Revised NOV2012 Page 6 of 28 FIGURE 1- CLOSED TEST TANK 5.2 Pressure Transducer A minimum of one pressu
44、re transducer shall be provided and mounted to the test-tank to measure the pressure generated by the inflator. Two pressure transducers may be used for due care to avoid data loss in the event pressure transducer malfunction occurs. The tank-pressure transducer mounting location should be away from
45、 dynamic flow regions. Pressure transducers may also be provided to measure the inflators internal pressure. An additional pressure transducer may also be used as a time-to-first-gas indicator which may be located closer to the inflator exhaust and located within the dynamic flow region. Strain gage
46、 or piezoelectric pressure transducers are both acceptable. Strain gage type pressure transducers may be unamplified or amplified. Pressure transducers are selected based upon how they are to be used, the speed and range of expected pressures, where they are to be mounted, and the temperature to whi
47、ch they are exposed. Where practicable, pressure transducers used for comparison testing should be standardized. Results from different transducer types or models may vary significantly - especially when measuring short duration pressure pulses. All transducers, instrumentation, and data filters (an
48、alog and digital) should be selected per SAE J211-1. The following Table shows an example of typical requirements and selection guidelines. SAE J2238 Revised NOV2012 Page 7 of 28 Transducer Selection Criteria Criteria Specification Definition Minimum Accuracy 0.5% F.S.O. (Full Scale Output) Percent
49、of full-scale-output Transducer F.S.O. (Full Scale Output) Selection Expected Tank Peak Pressure should be within 20% to 80% of the Transducer F.S.O. Tank Pressure Gage Resonant Frequency 4 kHz The mechanical resonant frequency of the pressure sensing assembly; the frequency of pressure application at which the transducer responds with maximum output amplitude. Response Time 0.33 ms The time required for the output to increas
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