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Welcome to Issue #73   

 

你好! ("Hello," pronounced nih hu in Chinese.) In case you've been wondering, each month we've been working our way around the world learning how to say "hello" in many different languages. This lap around the world is very similar to the way our calibration support team has been responding. This year we've been to every continent (except Antarctica!) in support of dynamic calibration standards committees, technical conferences, educational calibration seminars and customer installations. It's a very rewarding feeling to be supporting many of the world's leading companies...and reassuring to "break bread" with so many people of different cultures. The world can be a complicated place, but we're all in this together.
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Tip of the Month: 

Low-Frequency Calibration  

Remember when working at vibration calibrations of less than 5 Hertz, it's often helpful to select a higher sensitivity reference accelerometer (for example 500 mV/g) due to the small acceleration levels of displacement stroke limited exciters. Alternatively, optical displacement vibration reference methods are now available for ultra-low-frequency calibration. 

Technical Exchanges
Quick Links
PTB 
ISO TC 108 - Mechanical vibration, shock and condition monitoring
ISO TC 108/SC 3 - Use and calibration of vibration and shock measuring instruments
ISO TC 108/SC 6 - Vibration and shock generating systems
SAVE (Formerly SAVIAC)
Previous Newsletters
Dynamic Sensors & Calibration #72
Calibrate Our Own Accelerometers?; Monitoring Structural Dynamics with a Microphone

Dynamic Sensors & Calibration #71
Pressure Calibration in Ballistics Testing; Shakers & Accelerometers 
Select Newsletter Articles 
by Topic
PCB Group Companies
Load Cells: An Overview of Their
Design and Application
By Kenneth Watkins, PCB Load & Torque
Product Manager
PCB Load & Torque, Inc. load cells consist of specially designed structures which perform in a
predictable and repeatable manner when a force is applied. The force applied is translated into
a voltage by the resistance change in strain gauges, which are intimately bonded to the
transducer structure. The amount of change in resistance indicates the magnitude of
deformation in the transducer structure and hence the load applied.

The strain gauges are connected in a four arm Wheatstone Bridge configuration, which... 

 

Click to read full article

modalshop.com/calibration.asp?ID=892

World's Longest Running Continuous Building Vibration Monitoring System Completes 25th Year
The San Jose Center for Performing Arts was designed by architect Frank Lloyd Wright. Unfortunately, Wright died prior to the completion of the project. Wright's Grand Tier balcony design is unique and graceful, especially when viewed from the seating below, because it is only attached to the building structure at its ends and not along its back edge. Thus, the Grand Tier's design is more like a bridge than like a conventional balcony. An unanticipated and undesired
consequence of this bridge-like design is that
it was sometimes excited to uncomfortable
levels of vibration by audience-generated forces.
In the late 1980s Response Dynamics was hired to perform dynamic testing of the Grand Tier balcony
structure...   
 
modalshop.com/calibration.asp?ID=893
Blast From the Past: Non-Traditional Uses of ICP™ 'Power' Sensors  
[Excerpted from Sound & Vibration magazine] 
Over the past decade or so, sound and vibration test professionals, particularly those in the automotive NVH
and aerospace markets, have developed measurement applications that use more and more microphone channels. Given the increasing availability of dynamic measurement channels, the first "new generation," ICP-powered sensors were created. Driven by such large, multichannel applications as near-field acoustic holography (NAH), temporal array and inverse frequency response function techniques, two measurement systems utilizing dozens, if not hundreds of microphones have become more common...

                                       Click to read full article
modalshop.com/calibration.asp?ID=661
 

 

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,

Mike Lally signature
Michael J. Lally
The Modal Shop
A PCB Group Company