Strain gages

Use a strain gage to specify a nodal or elemental location on the model at which to evaluate stress or strain results in a specified direction. Strain gages define:

• Location

• Coordinate system for the stress or strain results

• Components of the stress or strain results

After defining strain gages, you can create an analysis event and then perform an evaluation for selected strain gages on the model. The Evaluate Strain Gages command generates stress or strain results for selected data components (for example, XX, YY, XY, Von Mises, or the legs of the strain gage).

0-45-90 Rosette strain gage capturing stress in three directions on an element face

Strain gage types

The four strain gage types represent some of the most widely used foil-type strain gages.

Type	Description	Graphical representation
Uni-axial	Single strain gage “leg” (or grid) for measuring stress or strain in a single direction (the direction in which the strain gage is oriented). The arrow in the strain gage icon identifies the X direction in the local strain gage coordinate system.
Bi-axial	Two strain gage legs, stacked perpendicular to each other, for measuring principal stresses or strains in two known directions.
0, 45, 90 Rosette	Three strain gage legs, stacked in 0, 45, and 90-degree angles, for determining principal stresses and strains and the direction of the stress or strain.
0, 60, 120 Rosette	Three strain gage legs, stacked in 0, 60, and 120-degree angles, for determining principal stresses and strains and the direction of the stress or strain.

Evaluating strain gages

When you request response results for a strain gage, you choose the data component to specify the direction for the evaluation (in the strain gage local coordinate system), including XX, YY, XY, and so on. You can also evaluate in the direction of the strain gage legs.

Sample stress results for rosette-type strain gage

If you specify the strain gage legs for the response request, note that the strain gage icon identifies Leg1 with an arrow. Moving clockwise, Leg2 is the next leg, and then Leg3. The arrow also identifies the X direction in the strain gage local coordinate system, which is used for the other evaluation data components as well.

Results calculations

Results for strain or stress in the XX, YY, or XY components are generated in the strain gage local coordinate system. The software calculates strain for the local strain gage coordinate system as follows.

Uni-axial

Bi-axial

0, 45, 90 Rosette

0, 60, 120 Rosette

When you define a strain gage on an element center, only the element face centroid results are generated. When you define a strain gage on a node, the nodal average results are generated.

The software calculates the Leg results as follows.

Uni-axial

Bi-axial

0, 45, 90 Rosette

0, 60, 120 Rosette

When you evaluate the Uni-axial or Bi-axial strain gages, the software does not generate a function result for the zero terms (for example, ).

Function names

Response functions are stored as function records in an AFU file with the same name as your Response Dynamics solution process.

In the AFU file, the node ID, evaluation data component, and shell element location (top or bottom) are reflected in each function's name. For example, MyStrainGage_1_(345VONMTOP) means that the strain gage was defined on node 345 on the top of the shell element and was evaluated for von mises stress.

Where do I find it?

Application	Pre/Post
Prerequisite	A Simulation file as the work part and displayed part
Command Finder	Strain Gage
Simulation Navigator	Right-click the Strain Gages node→New Strain Gage

How do I

Place and evaluate strain gages

Modify the display of sensors and strain gages

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

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Strain gages, Simcenter 3D 2021.1 Series

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