WMA NVH Analysis

WMA NVH (Noise, Vibration and Harshness) System

The WMA Vibration Analysis System was developed for production environments and is available to assist test engineers with NVH testing needs. The system is available stand alone or as a closely integrated toolkit to the WMA Test System. The WMA Vibration Analysis System consists of two major components:

	Processes that run in the background to collect and analyze on-line vibration data, as well as provide operators with pass/fail information related to vibration.
	A graphical user interface, which provides a set of analysis and graphical tools for post-mortem analyses of parts.

The background processes run continuously either as a stand-alone test system or closely integrated with the WMA Transmission Test System. When integrated, many of the WMA Test System’s tools are available. The centralized parameter database and editors are available to manage the vibration related parameters and test data points. Both stand and model specific parameters are available. Test sequence callable functions are available to control the vibration test, while the standard test system reporting tools are available to view the results (such as the Full Report and Trend Chart etc). When the test produces a vibration reject, repairmen or engineers may invoke the graphical analysis tools to quickly locate the possible defects with the aid of predefined cursors and/or comments.

Current applications of our vibration analysis systems are conducting tests at steady state speeds to detect defective components in the transmission. Optional order tracking support may be used to conduct vibration tests under varying speeds. The order tracking function uses the digital re-sampling technique along with the encoder signals to get the points evenly spaced by shaft position (for parts with rotating elements).

Supported Data Acquisition Cards:

Three different data acquisition cards are available in the system depending on the I/O subsystem and performance requirements:

Xycom XVME-566 VME card, with an aggregate throughput of 100 KHz.

UEI PowerDAQ PCI card, with an aggregate throughput of 2.5 Mb/sec and 32K on-board buffering memory. This card uses buffering to allow continuous sampling at high speeds. When the buffer is half full it is DMA-ed into main memory across the PCI bus.

National Instruments PCI card, with an aggregate throughput of 2.5 Mb/sec. Note: this card uses automatic throttling of the sampling rate if the card cannot store the data due to CPU loading.

W.M. Associates is able to provide support for, and configure, other cards as needed. Components such as microphones, accelerometers and charge amplifiers are typically supplied by the customer or machine builder, but can be supplied by WMA as well. External measurement devices such as laser vibrometers can be interfaced as well.


	Use "Stencils" to define spectral testing: Besides the conventional band power limits, this system incorporates a stencil concept. Stencils use a set of calculated (via statistics) spectrums or templates to do pass/fail tests across the whole or specific frequency/order range(s). A given stencil contains many elements that specify start and end frequencies (or orders), and upper and/or lower limits for the current frequency/order region of the current element. *Training:* Maximize your software investment by purchasing training. Comprehensive training is critical to insure a well understood and effectively used system. Training is available for Operators, Maintenance Personnel, Engineers and Support Personnel.

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