Torsional vibration is an angular velocity fluctuation that twists shaft sections. These fluctuations are superimposed on the steady running speed and, coupled with machinery induced vibrations, can result in destructive effects which propagate to the whole system. Usually it is not possible to detect these vibrations with common accelerometers or proximity probes used to measure lateral vibration. ATA Engineering, Inc. is proud to announce the AR-101 system, an exciting new application for all torsional-rotational measurements. Based on the well known Vold Solutions VSI Rotate torsional analysis software and coupled with inexpensive, robust, AC/DC powered National Instruments™ PXI hardware, this specialized torsional vibration data acquisition system offers full 8-channel 80 MHz counters for both TTL tachometers and general purpose magnetic transducers, plus 4 analog 240 KHz input channels. In addition, the software can read data from many different data acquisition systems and formats allowing you to compare and analyze new data with archived sets of data from previous tests.

One TTL output is also provided for synchronizing the AR-101 with an existing data acquisition system, eliminating the need to purchase replacements for your existing expensive general vibration data collection hardware. Main features include:

• 8-channel, 32-bit TTL input with 1.25 nSec resolution
• 4-channel input with 240 kHz sample rate for variables associated with torsional measurements (position, pressure, torque, etc.)
• 1 TTL output to synchronize with external data acquisition systems
• Flexibility to expand data acquisition to 64 channels or more
• AC (100 - 230 V) / DC (9 - 30 V) powered
• LAN-interfaced to MS Windows™ laptops and notebooks

Highlights

The AR-101 is an extremely powerful tool for acquiring and analyzing rotational test data, and is particularly useful for the development of gear boxes, power trains and belt drive systems. Further, it will enable test labs to diagnose faults and malfunctions while relating acoustic and structural responses to torsional events. No matter what your tachometer transducer (TTL, magnetic or incremental encoder), the AR-101 will provide fast, simple, accurate and clean results—even for complicated multi-channel measurements—with a very simple and intuitive Windows-driven menu. Linear or angular vibrations will no longer be a mystery nor will transmission errors or belt slippage remain regular problems. By storing throughput data and analyzing in off-line mode, multiple analysis settings and algorithms may be applied to each data set without committing to parameters before the data is recorded. Based on inexpensive National Instrument™ PXI hardware, both AC and DC powered, the AR-101 is equipped with 8 channels of 80 MHz counter/timers that have excellent phase match.

Results are provided in angular displacement, velocity or acceleration, in degrees or radians. Additionally, the results may be scaled in appropriate units for standard vibration analysis, e.g., m/sec, or whatever you need. Tachometer calibration software allows correction of inaccurate tooth spacing, insertion of missing teeth, and compensation for vibration between the sensor and the structure. Calibration is easy and accurate and made possible by an automatic calibration procedure. No matter how precise the wheel teeth, each revolution is perfectly recognized and no tachometer sensor’s vibration will have any influence on final calculations. Advanced envelope analysis (Millstrum analysis) is standard with the AR-101. An optional interface to ME’scope™ modal analysis software provides animation capabilities which allow torsional mode shapes to be generated from real acquired data. Response amplitudes with phase information are easily shown.

Detailed, informative graphical representations of all data are available in both 2-D and 3-D formats, and the number of data curves which can be displayed simultaneously is limited only by the display resolution of your graphics card or monitor. Displayed data can be exported by a simple cut-and-paste click of your mouse to standard Windows programs like Word, Excel and PowerPoint. Multi-channel rotational speed calculations allow technicians to calculate transmission error (where sufficient number of pulses per revolution apply) and the speed difference between any of the 8 channels. Order Normalization offers accurate order tracking in large dynamic ranges. By resampling in the angle domain, better resolution in the low speed part of the signal is achieved; 32-bit computational analysis is used to achieve a better signal-to-noise ratio. The software can process data from your existing data acquisition system in any of the following source formats: Teac, Sony, HP-SDF, IOtech Zonicbook, National Instruments, Vibe-Tech, ASCII, WAV, MATLAB, Dactron, DAC, B+S, SDRC-UFF, MEGADAC, HeimBin, Nicolet Prism, LMS Pimento, IOtech, PRC, SDF, Odessey, STAC Rex, Polytec .pdv, DAT and SoMat Ease-SIF. Additional formats can be easily accommodated upon request. The AR-101 integrates with your existing data acquisition system, giving you the ability to associate rotational information with any acoustic or vibration phenomena. A TTL output is provided for synchronization purposes. RPM is then calculated from the raw data in a clean, fast and accurate way. Choices of waterfall or spectrogram displays will let you better evaluate your run-up/run-down data in full color, both for frequency domain data and angle domain data. Synchronous analysis represents time data, angle domain, in both waterfall and full color spectrograms. Order data is represented in a simple and intuitive way and may be viewed against time, frequency and RPM with both amplitude and phase information. Calculations are easily transferred by copying and pasting into Windows applications including spreadsheets, text files and presentations. A powerful cursor editing capability helps you choose between several automatic cursors and define rolling elements, gearbox meshes, and planetary cursors. Available options for the AR-101 include the Vold-Kalmann filter for transient torsional analysis and animation of torsional mode shapes capabilities through a direct link to ME’scopeVES™.