Sine Resonance Track & Dwell SRTD

Transcription

1 Sine Resonance Track & Dwell SRTD Todays Presenter: Kevin Van Popering We will begin shortly!

2 Sine Resonance Track & Dwell Testing Basic Method Conduct a Sine sweep over the desired frequency evaluation range Automatically determine resonances and display a table of results Select the desired frequencies from the table and either continue with a frequency Dwell or a Phase Tracked Dwell Applications Observe the product response Damage Duplication reproduce field failures at resonant frequencies Pass/Fail Criteria production or pre-production (are product resonances located in critical frequency ranges?)

3 Test Setup

4 Sine Test Profile Tab Click New Test Sine Simple vs. Advanced Profile Tab Set start amplitude and frequency Can include multiple steps Accel, Vel, and Disp limits shown below (system limits)

5 Sine Test Schedule Tab Select Sweep up or Sweep down under the Level Start drop down menu Typical Duration for Resonance detection is 1 sweep Control Channel Default is whatever channel is selected as control on the Channels Tab Can insert multiple levels Resonance Table View Report: Resonance Report Template

6 Set Sweep rate to be slow in order to accurately determine your resonance Typical: 3 Oct/min For sharp (High Q) resonances, make sweep rate extremely slow (.5 or even.1 Oct/min). For sweep profiles with multiple steps, individual sweep rates may be selected with the check box in the lower left corner Sine Test Sweep Tab For sweep profiles with multiple steps, individual Tolerances and Aborts may be set after selecting the check box in the lower right corner Example

7 Sine Test Table Tab Tables are a great tool for providing tabular data from an SRTD test Enter [PARAM]\t fields for up to 5 different tables (View:Report Parameters) or graphs For Each table, select how often to update the data and select Append to Test Notes for an updated onscreen data set.

8 Sine Test Resonance Tab Selection Parameters: Measurement: Defines which channel to search for resonances Selection Method: Curvature Q-Factor Transmissibility Diagram Sort Method Dwell order in resonance table Spacing: for resonances close together

9 Sine Test Resonance Tab Control Parameters: Feedback Gain How fast to adjust frequency when finding the resonance (.01) Max Sweep Rate Enter as a fraction of sweep rate on sweep tab (.1x) Max Drift maximum allowable drift in the resonance frequency (10%, 100Hz) Linear Feedback Range Sets phase error above which non-linear feedback is enabled

10 Resonance Table appears after sweep Sine SRTD Select which frequencies to test Duration: Time or Cycles Set Amplitude Set Control Channel Phase Tracking Click Continue button to run desired dwells

11 SRTD Phase Tracking Fixed Frequency Dwells Resonances decrease due to fatigue Product experiences less than peak acceleration Phase Tracking Phase of resonance does not change with fatigue Allows the tests frequency to match the changing resonant frequency

12 SRTD Checkbox SRTD New Controls Phase Direction Button Auto Direction Checkbox Feedback Gain Phase Angle Adjustment Mouse Wheel Demand Phase Channel Pair Selection Time-Based SRTD Graphs Phase-Based SRTD Graphs

13 VR s Standard SRTD Graphs

14 Thin Metal Beam Sine Sweep Resonance: 69.7 Hz T = 31 G/G Phase = Manual Control SRTD: T = 32.4 G/G Peak Transmissibility increased by 4.5%! Lawn Mower Blade Sine Sweep Resonance: 72.5 Hz T = 51 G/G Phase = -105 Manual Control SRTD -92 T = 54 G/G Peak Transmissibility increased by 5.9%! VRC Case Study

15 Back Transmissibility and Q-Factor

16 Back Different Sweep Rate

17 VR s New Manual SRTD Control Traditionally SRTD tests have controlled on frequency with little concern for phase 90 theoretical phase value is assumed (not always true!) Phase May be affected by: Location of the accelerometer Lag in the reading of instrumentation