What is a Sine-on-Sine (Multi-Sine) Test?
Engineers often use a standard SRTD test to bring the device under test (DUT) to failure. For fatigue testing, the engineer may need to run multiple sweeps through the frequency range at different sweep rates. The time required to do so can exceed tens of hours.
With a multi-sine vibration test, the engineer can run multiple sine tones at different rates simultaneously. This feature saves time for engineers running fatigue testing and allows for the excitation of multiple resonant frequencies at once.
Easy Test Entry
Enter frequency/amplitude breakpoints of the background random acceleration spectrum in an easy-to-read, tabular format. The operator can use frequency and amplitude breakpoints or enter one endpoint and the desired dB/octave slope. Over 1,000 separate frequency/amplitude breakpoints can be entered, allowing for the entry of virtually any test specification.
Multiple Sine Tones
1 to 32 true floating-point precision sine tones can be superimposed on the background random spectrum and swept back-and-forth between frequencies at a user-programmable rate. The amplitude and frequency sweep parameters are all user-programmable. Enter up to 200 separate frequency/amplitude breakpoints.
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, the number of sine wave cycles, or the 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.
What is Sine Resonance Track & Dwell (SRTD)?
A test engineer may run a sine resonance track & dwell (SRTD) after they have determined the resonances of a test item with a sine sweep. SRTD is meant to bring a product to failure by exciting a known resonance.
During a sine dwell test, the vibration controller runs a single sine tone at the product’s resonant frequencies rather than sweeping through the frequency range. A product experiences the most fatigue when exposed to its natural resonance. The test is run until failure occurs, or sufficient time has passed without failure.
Sine Resonance Phase Track & Dwell Software
Transmissibility peaks can be automatically detected from a sine sweep, and then dwell tests run at the detected resonance frequencies for a specified time duration or number of sine wave cycles. In a sine dwell test, the controller can automatically track the resonance frequency to keep the output on resonance even when fatigue damage causes the resonance frequency to shift. Track High Q or sharp resonances with advanced phase tracking controls that allow you to dial in on resonance and maintain peak amplitude by way of Phase vs. Transmissibility.
- Configurable Safety Limits: Configurable acceleration limits, line limits, and drive limits can be set by the user to protect the test article and shaker system. The control input is also verified against shaker acceleration limits.
- Test & Level Scheduling: Tests can be scheduled to run a user-defined length of time, the spectrum level can be scaled by a specified dB-level, percentage, or scaled for a specified RMS acceleration. Level schedules can be entered to run various durations at different acceleration levels.
- Data Plots: Available graph display options include acceleration spectral density, output voltage spectral density, and channel-to-channel transmissibility. Graphs can be easily auto-scaled, and cursor display can be adjusted. Data and text annotations can be easily placed on the graphs, and data values update live with changes.