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Shock and vibration data logger

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Shock and vibration logger with integrated 3-axis digital accelerometer and lithium-polymer battery

Ashock data loggerorvibration data loggeris ameasurement instrumentthat is capable of autonomously recordingshocksorvibrationsover a defined period of time. Digital data is usually in the form ofaccelerationand time. The shock and vibration data can be retrieved (or transmitted), viewed and evaluated after it has been recorded.

In contrast with a shock data logger, ashock detectoris used to indicate whether or not the threshold of specified shock has occurred.

Functions[edit]

A logger comprisessensorssuch asaccelerometers,storage media, a processor and power supply. The sensors measure and store shocks either as the entire waveform, summary data, or an indication of whether a threshold value was observed. Some devices have accelerometers built into the unit while others can use external accelerometers. The processor processes the measured data and saves it on the storage media together with the associated measurement times. This allows the measurement data to be retrieved after the measurements have been completed, either directly on the logger or via an interface to a computer. Some have an RFID interface.[1] Software is used to present the measured data in the form of tables or graphs and provides functions for the evaluation of the measurement data. The shock and vibration data is either recorded continuously over a defined time period or on an event-driven basis where the recording of data is determined by certain criteria. Employing such an event-based measurement method allows the recording of specific shocks that exceed a critical length of time or strength. Some have wireless capability such asBluetoothtransmissions to smartphones.[2]

Acceleration loggers usually use non-volatile storage media for recording the measurement data. These may be hard disc drives orEEPROMsfor instance. Such devices will not lose the data when the device is powered down. This also means that the measured data will remain stored in the event of a power failure.

Overview of shock measurement[edit]

Shocks and impacts are often described by the peak acceleration expressed in g-s (sometimes calledg-forces). The form of the shock pulse and particularly the pulse duration are equally important. For example, a short 1 ms 300 g shock has little damage potential and is not usually of interest but a 20 ms 300 g shock might be critical. Use ofshock response spectrumanalysis is also useful.

The mounting location also affects the response of most shock detectors. A shock on a rigid item such as a sports helmet or a rigid package might respond to a field shock with a jagged shock pulse which, without proper filtering is difficult to characterize. A shock on a cushioned item usually has a smoother shock pulse., and thus more consistent responses from shock detector.

Shocks are vector quantities with the direction of the shock often being important to the item of interest.

A shock data logger can be evaluated: separately in a laboratoryphysical test,perhaps on an instrumented shock machine; or mounted to its intended item in a testing laboratory with controlled fixturing and controlled input shocks; or in the field with uncontrolled and more highly variable input shocks.

Use of propertest methods,calibration,andVerification and validationprotocols are important for all phases of evaluation.

Monitoring of goods in transit[edit]

Shock loggers can be used to monitor fragile and valuable goods during transit and to measure the transportation shock and vibration environment.[3][4] The loggers can be rigidly attached to the goods, packaging, or transport vehicles so that they can record the shocks and vibrations acting upon them. Some large items may have several shock sensors to measure different locations. The measured data reveals whether the goods in transit have been subjected to potentially damaging conditions. Based on this data, the options may be:

  • If there have not been unusual shock or vibration continue to use the shipment as is, without special inspection
  • If potentially damaging hazards have occurred, thoroughly inspect the shipment for damage or conduct extracalibrationprior to use
  • The consignee may choose to reject a shipment where sensors indicate severe handling
  • The time of the damage, orGPS tracking,may be able to determine the location of the damaging shock or vibration to direct appropriate corrective action.

Shock and vibration data from multiple replicate shipments can be used to: compare the shipment severity of different routings or of logistics providers;[5] or develop composite data to be used inpackage testingprotocols. The shock handling data is often most useful converted from accelerations to drop heights or other means of quantifying the severity of impacts. Several means of statistical analysis of drops and impacts are available.[6]Vibration data is often most useful in power spectral density format which can be used in to control random vibration testing in a laboratory.

Other applications[edit]

Acceleration logger measuring vibrations on a tool carousel of a CNC lathe

Among other applications, acceleration sensors are used to:

  • Measure accelerations in motor vehicles, for example during the reconstruction of road accidents.
  • Monitor machinery used onproduction linesthat is sensitive to shocks or vibrations.
  • Monitor and reduce wear in industrial plants and for increasing the performance of machines.
  • Monitor and record earthquakes.
  • Monitor trucks for excessive jolts[7]
  • Measure vibrations inwind turbines
  • Record input shocks and vibrations to humans[8]
  • Record movement data for health management, patient monitoring.
  • Animal monitoring of breathing, walking, standing, lying and sleeping behaviour.
  • Measuring acceleration for avalanche emergency systems.
  • Measure impacts to sportshelmetsandbiomechanicstesting[9][10][11]
  • Determine theg-forcesacting on people when riding rollercoasters.
  • Establish accelerations for objects onconveyor belts.

See also[edit]

References[edit]

  1. ^Todd, B; Schltz; Hawkins; Jensen (2009). "Low Cost RFID Threshold Shock Sensors".IEEE Sensors Journal.9(4): 464–469.Bibcode:2009ISenJ...9..464T.doi:10.1109/jsen.2009.2014410.S2CID36057599.
  2. ^Duffy, A (November 26, 2011),"Ottawa entrepreneur's Shockbox helmet sensor acts to mitigate concussion damage",Ottawa Citizen,archived fromthe originalon 28 November 2011,retrieved16 Mar2012
  3. ^Kipp, W (1998), "Understanding Today's Transport Environment Measuring Devices",ISA 44th International Instrumentation Symposium(PDF),ISA,retrieved8 Mar2012
  4. ^"Shipping Monitor"(PDF),Spinoff 2000,NASA, January 2000,retrieved30 Oct2014
  5. ^Singh, J; Singh, Burgess (July 2007),"Measurement, Analysis, and Comparison of the Parcel Shipping Shock and Drop Environment of the United States Postal Service with Commercial Carriers",Journal of Testing and Evaluation,35(3): 100787,doi:10.1520/jte100787
  6. ^Sheehan, R (August 1997),Analysis Techniques for Package Distribution Environment Data,Test Engineering &Management, pp. 18–20
  7. ^Miller, R. E.; Walden, J; Rhoades, S; Gibbs, R (2010), "Acceleration and GPS Data Monitor Truck Haulage Jolts",Min Eng 2000 52(8):2010(PDF),NIOSH,retrieved29 Mar2012
  8. ^ Milosavljevic, Stephen; David I. Mcbride; Nasser Bagheri; Radivoj M. Vasiljev; Ramakrishnan Mani; Allan B. Carman; Borje Rehn (2010),"Exposure to Whole-Body Vibration and Mechanical Shock: A Field Study of Quad Bike Use in Agriculture",Annals of Occupational Hygiene,55(3): 286–295,doi:10.1093/annhyg/meq087,PMID21220741,archived fromthe originalon 15 April 2013,retrieved29 March2012
  9. ^Jones, W D (October 2007). "Helmets Sense the Hard Knocks".IEEE Spectrum:10–12.doi:10.1109/MSPEC.2007.4337656.S2CID36488065.
  10. ^Moore, N C (29 January 2014)."Understanding concussions: Testing head-impact sensors".Michigan News.University of Michigan: 10–12.Retrieved3 Nov2014.
  11. ^"Helmet Testing".6 March 2018.

Books and general references[edit]

  • Gilmore (editor), Measurement and Analysis of the Distribution Environment, Final Report, Protective Packaging Committee IoPP, Hewlett Packard, 1999
  • Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009,ISBN978-0-470-08704-6
  • DeSilva, C. W., "Vibration and Shock Handbook", CRC, 2005,ISBN0-8493-1580-8
  • Harris, C. M., and Peirsol, A. G. "Shock and Vibration Handbook", 2001, McGraw Hill,ISBN0-07-137081-1
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