Best Practices for Strain Gauge Correlation

Transcription

1 Best Practices for Strain Gauge Correlation Joe Spadola October 5-6,

2 Correlating the FE Model with Reality 2 Objective To use the virtual strain gauge to correlate an FE model s results with measured strain data Does the FE model predict stress or strain correctly? The virtual strain gauge outputs strain time series. These may then be correlated to real measured strain gauge data. October 5-6,

3 Virtual Strain Gauge 3 The Virtual Strain Gauge provides a unique, powerful way to correlate physical tests with FE models This tool is available in the FEInput glyph via a toolbar icon Once activated, the user can place the gauge with one of the following options Manually keyed IDs Coordinates Pick tool October 5-6,

4 Virtual Strain Gauge 4 Multiple virtual strain gauges can be placed on a model Gauges can be imported/exported Gauges can be saved in a process October 5-6,

5 Virtual Strain Gauge Process 5 The type of strain gauge can be Single, Tee, Rosette, and Delta The orientation can be controlled by: XYZ Vector 2 Nodes Angle Offset October 5-6,

6 Correlation and Hotspot Strains 6 Engineering Task Details Gage Location Advantage Disadvantage Structural analysis Measure peak strain Predict strength and durability Local hotspots Measures peak strain Very sensitive to location and orientation Correlation with FEA Compare with FE strains Validate FE model Nominal stress areas Insensitive to location and orientation Doesn t measure peak strain Don t try to correlate virtual and measured strains in areas of high stress concentration. Focus on areas with low stress gradients. October 5-6,

7 Strain Gauge Correlation 7 Comparison of virtual strain and measured strain How does one know if the two are well correlated? October 5-6,

8 Strain Gage Correlation 8 Are they similar in shape? Have I done this correctly? YES NO October 5-6,

9 Strain Gage Correlation 9 Is the polarity correct? Are my FE loads applied in the correct direction? Zoom in at select areas YES NO October 5-6,

10 Strain Gage Correlation 10 Is the polarity correct? Are my FE loads applied in the correct direction? Look at shape of crossplot YES NO October 5-6,

11 Strain Gage Correlation 11 Is the polarity correct? Are my FE loads applied in the correct direction? Pro tip: if your data looks ok but out of phase F2+LMB October 5-6,

12 Strain Gage Correlation 12 Are the magnitudes about the same? Have I captured all the FE loads I need? Are they ALL applied in the correct direction? Have I captured/used the correct input load histories? YES NO October 5-6,

13 Strain Gage Correlation 13 Are they both active/inactive at the same time? Have I captured all the FE loads I need? YES NO Low Activity Highly Transient Inactive Something is wrong October 5-6,

14 Summary of Best Practices 14 Don t try to correlate virtual and measured strains in areas of high stress concentration Rerun with the gauge moved slightly to check sensitivity Focus on areas of nominal but active stress regions Don t be overly concerned with magnitudes October 5-6,

15 Joe Spadola Applications Engineer T: E: October 5-6,