Pressure Calibration in Ballistics Testing
By Mike Dillon, Pressure Calibration Product Mgr |
 PCB Piezotronics recently hosted a two-day pressure measurement and calibration training in Depew, NY for the Sporting Arms & Manufacturer's Institute (SAAMI). This group's Technical Committee develops product standards for firearms and ammunition. The Modal Shop also attended the training, supporting the metrology aspects of the program.
One of the topics discussed was fundamental measurement problems in ballistics. A key issue is the fact that the transducer needs to be as close as possible to the physical event while at the same time not interfering with the measurement event. In this case, we want to measure the pressure change inside a piece of ammunition when it is fired. To put the sensor inside the brass casing is impossible. So the measurement alternative is to put it on the outside of the brass casing and measure the pressure event on the outside of the brass casing...
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Shakers and Accelerometers
By Marco Peres, Structural Test Product/
Portable Vibration Calibrator Product Manager |
Electrodynamic Shakers and piezoelectric
 accelerometers are widely used in the field of vibration in applications like experimental modal analysis. Without getting too technical, one can describe modal analysis as the process whereby we describe a structure in terms of its natural characteristics--which are its natural frequencies, damping and mode shapes - i.e. its dynamic properties.
In an effort to demystify the practical aspects of modal testing, earlier this year University of Massachusetts Lowell professor Peter Avitable and students Sergio Obando (featured in the picture) and Julie Harvie, joined The Modal Shop at the IMAC conference for a hands-on tutorial presentation on shaker test set-up. The presentation was the result of a paper presented during the ISMA conference in Belgium last year titled: "Effects of Shaker, Stinger and Transducer Mounting on Measured Frequency Response Functions - Proceedings of ISMA2012."
Another interesting article on the practical aspects of modal testing was published a few years ago in Sound & Vibration magazine.
Last but not least, for those of you who are new to the world of modal analysis, make sure to download and read the series of articles from professor Peter Avitable.
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Blast From the Past: The Language of Metrology
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The Modal Shop has been actively presenting one-day seminars on dynamic sensing and calibration around the world. This education on the function and structure of dynamic sensors (PE, VC, PR, etc) and 
the associated methods and means of calibration is key in keeping pace with global growth in acceleration sensing.
Ensuring the users' control
and confidence in dynamic analysis serves the measurement and engineering community, in everything from aerospace structures to consumer electronics to plant floor efficiencies.
The following is a presentation used to orient audiences in the framework of metrological terminology. This presentation makes a nice primer, or overview, to share with your new hires and also includes a number of handy links to other useful resources.
Additionally, on September 10th The Modal Shop will be hosting a "Dynamic Sensors & Calibration" Open House. For more information or to register, click here.
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Thanks for joining us for another issue of "Dynamic Sensors & Calibration Tips." As always, please, speak up and let us know what you like. We appreciate all feedback: positive, critical or otherwise. Take care!
Sincerely,
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 Michael J. Lally A PCB Group Company
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