When to use displacement, velocity or acceleration amplitude units in vibration analysis?

A novice vibration analyst always has a question whether to use displacement, velocity or acceleration amplitude unit? Here is a rule of thumb based on the frequency.
Displacement is a good measure at lower frequencies especially less than 5 Hz. The failure mode is generally the “stress” causing due to the displacement. Velocity measures how often the displacement is being applied in a given time period. It is related to the fatigue mode of failure. Velocity amplitude unit is a good measure in the range of 5-2000 Hz frequency. Even at small displacement amplitude the repeated motion can cause fatigue failure. Above the 2000 Hz the failure is normally force related. Acceleration is measure of the likelihood of force being the mode of failure.
There are areas on chart where stress, fatigue and force related failures overlap. The proper selection of amplitude unit will depend upon the application under study. Note that frequency, displacement, velocity and acceleration are related. Knowing any 2 quantities, other variables can be easily calculated.

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Open Source Manufacturing

The open source software community has grown exponentially over the past several years, and it continues to do so along with expanding to previously closed source territory. More and more processes once run by closed source software are moving in the direction of open source software to take advantage of the reliability, accessibility and lower cost. One very well known open source software bundle is the LAMP stack for building software applications. Each portion (L-Linux, A-Apache, M-MySQL, P-PHP) is open source and free for anyone to obtain, and more and more companies are using it as a medium for creating software applications. However the manufacturing community has failed to embrace these changes and lower the costs associated with manufacturing information technology. Manufacturing continues to remain closed source, proprietary and non-scalable.
In this effect, we demonstrate the manufacturing open source stack ULMF (U-Ubuntu, L –LinuxCNC, M-MTConnect, F-Firefox) to create an open source bundle for use in the manufacturing world. ULMF is developed as part of the supervisory system thrust area for the Smart Machine Platform Initiative (SMPI). The supervisory system is defined as a system that integrates and coordinates multiple process monitoring and control modules such that a globally optimal machining solution could be delivered real-time for desired quality and maximum productivity.In this paper, we will lay out the methods to use open source applications to create a functional CNC control that is capable of obtaining and displaying data using Ubuntu operating system, LinuxCNC-EMC (Enhanced Machine Controller), MTConnect and Firefox internet browser. MTConnect is a royalty-free open communication standard for interconnect ability in the manufacturing arena. The free and open standard allows devices and systems to send out understandable information in the required format. Architecture of the ULMF stack and MTConnect standard is explained in depth. This paper explains why an open source bundle is important to the manufacturing community as well as the potential ramifications of using open source to apply to manufacturing data management solutions. The potential benefits include knowledge management, real-time data access, scalability, plug-and-play functionality and data mining capabilities.

Reference: Open Source Manufacturing, 2009 conference of the Society For Machinery Failure Prevention Technology, Dayton, Ohio, 28-30 April 2009.
Authors: Pierce Kuhnell, Amit Deshpande