Persistent Link:
http://hdl.handle.net/10150/609329
Title:
Removing Resonances in Automotive Crash Test Instrumentation
Author:
Gardenhire, Lawrence W.
Issue Date:
1975-10
Rights:
Copyright © International Foundation for Telemetering
Collection Information:
Proceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection.
Publisher:
International Foundation for Telemetering
Journal:
International Telemetering Conference Proceedings
Abstract:
Unwanted resonances can make analysis of crash instrumentation extremely difficult. These resonances are a natural part of the acceleration measurements and in many cases are allowed to be present to maintain the needed high-frequency responses. Crystal accelerometers are, for instance, essentially undamped, and have resonance humps 40 dB above unity in order to maintain a flat response to approximately one-half the resonance or natural frequency of the accelerometer. This resonance also allows the phase angle response to be close to zero well out towards the natural frequency. Additional resonance problems exist in the mounting brackets, or as frame resonances which carry little or no information. The process of removing them, however, can produce extreme errors in both amplitude and phase. The SAE J211a Recommended Practice recommends four channel classes for impact tests: c1asses 60, 180, 600, and 1000. The frequency response is flat to +1/2, -1 dB to these frequencies, and to +1, -4 dB to the break frequencies of 100, 300, 1000, and 1650 Hertz. The filter rolloff is nominally 12 dB/octave (second order) from these break points. Second order filters are normally used for impact tests since accelerometers have second order response. This filtering will provide satisfactory results, if no resonance is present at less than several times the class frequency. Often the next lower class is used to remove a resonance, a step that may cause large errors. A better solution is to follow the typical class filter with a sharper cutoff filter that will remove the resonance without affecting the amplitude and phase of the initial impulse. A method that determines when data is lost by excessive filtering is presented and demonstrated on two crashes. One crash has a resonance about 15 times higher than the class; one is less than 3 times higher.
Sponsors:
International Foundation for Telemetering
ISSN:
0884-5123; 0074-9079
Additional Links:
http://www.telemetry.org/

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleRemoving Resonances in Automotive Crash Test Instrumentationen_US
dc.contributor.authorGardenhire, Lawrence W.en
dc.date.issued1975-10en
dc.rightsCopyright © International Foundation for Telemeteringen
dc.description.collectioninformationProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection.en
dc.publisherInternational Foundation for Telemeteringen
dc.description.abstractUnwanted resonances can make analysis of crash instrumentation extremely difficult. These resonances are a natural part of the acceleration measurements and in many cases are allowed to be present to maintain the needed high-frequency responses. Crystal accelerometers are, for instance, essentially undamped, and have resonance humps 40 dB above unity in order to maintain a flat response to approximately one-half the resonance or natural frequency of the accelerometer. This resonance also allows the phase angle response to be close to zero well out towards the natural frequency. Additional resonance problems exist in the mounting brackets, or as frame resonances which carry little or no information. The process of removing them, however, can produce extreme errors in both amplitude and phase. The SAE J211a Recommended Practice recommends four channel classes for impact tests: c1asses 60, 180, 600, and 1000. The frequency response is flat to +1/2, -1 dB to these frequencies, and to +1, -4 dB to the break frequencies of 100, 300, 1000, and 1650 Hertz. The filter rolloff is nominally 12 dB/octave (second order) from these break points. Second order filters are normally used for impact tests since accelerometers have second order response. This filtering will provide satisfactory results, if no resonance is present at less than several times the class frequency. Often the next lower class is used to remove a resonance, a step that may cause large errors. A better solution is to follow the typical class filter with a sharper cutoff filter that will remove the resonance without affecting the amplitude and phase of the initial impulse. A method that determines when data is lost by excessive filtering is presented and demonstrated on two crashes. One crash has a resonance about 15 times higher than the class; one is less than 3 times higher.en
dc.description.sponsorshipInternational Foundation for Telemeteringen
dc.identifier.issn0884-5123en
dc.identifier.issn0074-9079en
dc.identifier.urihttp://hdl.handle.net/10150/609329en
dc.identifier.journalInternational Telemetering Conference Proceedingsen
dc.typetexten
dc.typeProceedingsen
dc.relation.urlhttp://www.telemetry.org/en
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