strain gauge best practices [Read-Only]Best Practices for Strain Gauge Correlation Joe Spadola ......

© 2016 HBM

HBM Prenscia: Business Document

Best Practices for Strain Gauge Correlation

Joe Spadola

2016 nCode User Group Meeting

© 2016 HBM October 5-6, 2016 www.ncode.com

© 2016 HBM


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• 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.

Correlating the FE Model with Reality



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• 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

Virtual Strain Gauge



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• Multiple virtual strain gauges can be placed on a model

• Gauges can be imported/exported

• Gauges can be saved in a process

Virtual Strain Gauge



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• The type of strain gauge can be• Single, Tee, Rosette, and Delta

• The orientation can be controlled by:• XYZ Vector

• 2 Nodes

• Angle Offset

Virtual Strain Gauge Process



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6Correlation and Hotspot Strains

EngineeringTask Details Gage

Location Advantage Disadvantage

Structuralanalysis

• Measure peak strain

• Predict strength and durability

Localhotspots

Measurespeak strain

Very sensitiveto location and orientation

Correlation with FEA

• Compare with FE strains

• Validate FE model

Nominalstress 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.



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• Comparison of virtual strain and measured strain• How does one know if the two are well correlated?

Strain Gauge Correlation



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• Are they similar in shape?• Have I done this correctly?

Strain Gage Correlation

YES NO



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• Is the polarity correct?• Are my FE loads applied in the correct direction?

• Zoom in at select areas


YES NO



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• Look at shape of crossplot


YES NO



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• 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



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• Are they both active/inactive at the same time?• Have I captured all the FE loads I need?


Inactive

Highly Transient

Low Activity

YES NO

Something is wrong



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• 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

Summary of Best Practices



strain gauge best practices [Read-Only]Best Practices for Strain Gauge Correlation Joe Spadola ......

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