After determining transmissibility peaks, run a dwell test at resonant frequencies for a specified time duration or number of sine wave cycles. Sine resonance track & dwell (SRTD) excites the known resonance until failure or sufficient time has passed without failure. SRTD is a feature of the Sine software.
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Enter frequency/amplitude breakpoints in an easy-to-read, tabular format. The operator can select to control constant or ramped acceleration, velocity, or displacement. Automatically calculate and enter the frequency of intersection between any combination of constant acceleration, velocity, or displacement lines. Over 1,024 separate frequency/amplitude breakpoints can be entered, allowing entry of virtually any test specification. 
Configure up to 512 input channels with either multi-channel averaging or multi-channel extremal control. A standard frequency range is DC-4,990Hz which can be extended up to 50,000Hz with the VR9103 High-Frequency option. These inputs allow for more than one input channel (multi-channel extremal) for control in a control strategy where the highest, lowest, or average of accelerometer readings will be used for control of the test.
Linear sweep type (Hz/minute or minutes/sweep) or logarithmic (octave/minute, decade/minute, minutes/sweep) sweeps can be specified and changed while running the test. The test duration can be entered in terms of length of time, number of sine wave cycles, or number of sweeps. Sequences of fixed-frequency tones of a specified acceleration, velocity, or displacement can be run. Looping functions allow easy entry of repeating tone sequences. Input channels have individually selectable tracking filters (user-configurable) to remove harmonics and out-of-band noise from the measurements.
A configurable large numeric readout displays the current test frequency and channel amplitudes. Use the manual control to manually control the sweep direction, sweep rate, and scale the amplitude with your mouse cursor.
The controller can be configured to abort if the controlled acceleration goes above or below the desired level by an operator-configured number of dB. Abort limits can also be enabled for individual monitoring channels. Drive limits can be configured to protect from overdriving your shaker in case of failed accelerometers.
An engineer runs an SRTD test after determining the resonances of a test item with a sine sweep. An SRTD test brings a product to failure by exciting a known resonance. During the sine dwell test, the vibration controller runs a single sine tone at the product’s resonant frequencies rather than sweeping through the frequency range.
During a sine dwell test, the controller can automatically track the resonance frequency so that the output remains on the resonance even if fatigue damage shifts the resonance frequency. In VibrationVIEW, track high Q or sharp resonances with advanced phase tracking controls that allow the user to dial in on resonances and maintain peak amplitude by way of phase versus transmissibility.
Resonance occurs when the frequency of an external force is the same or nearly the same as the natural frequency of a structure. The frequency response of the structure is amplified when its natural vibration is excited, which can result in structural fatigue or damage.
The user can manually change SRTD settings during a test and receive feedback on current test settings in the SRTD Controls dialog box.
The time-based SRTD graphs display long-term changes in the resonance frequency due to fatigue or product temperature. The phase-based SRTD graphs have a custom layout.
Peak tracking in VibrationVIEW automatically shifts resonances by finding and maintaining the peak transmissibility between two channels.
Peak tracking oscillates the phase between the two channels and observes increases or decreases to the peak transmissibility. As more data is collected, the phase change becomes narrower in frequency and slower in time. This change limits the amount of oscillation while accurately tracking the peak.
This powerful feature minimizes the need for precise detection during the sine sweep so the user can sweep faster. Most importantly, it maintains peak transmissibility throughout the tracked dwell portion of the test.
A sine sweep test may display oscillations in the presence of high-Q resonances. The engineer can address the oscillations in several ways, such as adjusting the response time or tracking filters. However, in some situations, these parameters are fixed and cannot be adjusted. In such instances, the user can use the Adaptive Feedback option.
Adaptive feedback allows for tighter control while limiting problems in a resonance. A majority of the test only requires one set of test settings. As the test sweeps through the resonance and begins losing control, the software automatically adjusts the response time and slew rate to more appropriate settings. Adjustments may include:
Adaptive feedback has a low, medium, or high setting. Alternately, the user can select manual control. We recommend using the manual settings as a last option.
