Tension and Torsion test challenge

CHALLENGE

Perform tension and torsion test on the specimen provided.

OBJECTIVE

Tension Test- Displace one end of the specimen by 18mm while keeping the other end fixed.

Torsion Test- Displace one end of the specimen by 1200 degrees while keeping the other end fixed.

Find out Equivalent Stress, Total Deformation and Temperature (User Defined Result) for both cases and compare the results.

--------------------------------------------------------------------------------------------------

For the given challenge, we are simulating the results using explicit dynamics module on ANSYS workbench.

After loading the explicit dynamics module, the file is renamed based on convenience. The material used for analysis is Steel 1006. It is selected from Explicit Materials menu inside Engineering Data Sources.

The given geometry is loaded on SpaceClaim for verification and post checking the ANSYS Mechanical APDL is launched for beginning the analysis. The SpaceClaim geometry looks as follows

Since this is a simple model, we are only concerned about meshing and defining the boundary conditions.

Tension Test

Mesh

We choose a Tetrahedron patch conforming method for the given geometry. In patch conforming method, the model is meshed from volume to edges. The given workpiece is a geometry with varying cross-sections and tetrahedron elements are best suited for accurately meshing this model.

Next, we define two Coordinate Systems, one for each end of the workpiece. This is done so that meshing can be done as per sphere of influence.

Once the coordinate systems are defined, by selecting Face Sizing and Sphere of Influence, we mesh the two end portions of the workpiece. A sphere of radius of 22mm and element size of 3mm is selected. The resulting mesh looks as follows.

Analysis Settings

Since this is an Explicit Dynamics analysis problem, there are no time steps involved. In this case, we are analyzing the results over a very short period of time (End Time.) The time period selected for analysis is 0.001s (1 millisecond.)

Boundary Conditions

For analyzing the results for tension test, one end of the workpiece is kept fixed and displacement of 18mm is applied on the free end in the positive X direction.

The next step is to run the solver to calculate the Equivalent stress, Total Deformation and Temperature (User Defined Result) developed in the workpiece at the end of 0.001s.

The User Defined Result for Temperature can be obtained after the solution has been generated. It can be obtained from the WORKSHEET menu in the toolbar.

Results:

Tension Test

Equivalent Stress= 628.48 MPa (Max)

Total Deformation= 18.003 mm (Max)

Temperature= 267.31 deg Celcius (Max)

Torsion Test

Mesh

In continuation of the meshed model used for tension test, further refinement is carried out by defining a face sizing of 1.5mm for the filleted portions. The center portion is meshed using a Sphere of Influence with 8mm radius and element size of 1mm.

Changing The Nature of displacement

While we defined a linear displacement of 18mm for tension test, in this case, a rotational value of 1200 degrees is defined. This is done by adding a “Cylindrical” Coordinate system at the center of the workpiece and adjusting the axes to match the direction of rotation.

Results:

Torsion Test

Equivalent stress= 649.35 MPa (Max)

Total Deformation= 12.249 mm (Max)

Temperature= 436.7 deg Celcius (Max)

Results Summary

	Total Deformation Max (mm)	Equivalent stress Max (MPa)	Temperature Max (Deg Celcius)
Tension Test	18.003	628.48	267.31
Torsion Test	12.249	649.35	436.7

My Inference:

Tension Test

• Max Equivalent Stress is developed in the center portion of the workpiece, where neck formation occurs. Although the workpiece is deformed beyond the elastic limit and necking has happened, Fracture has not yet occurred for the given value of displacement.
• Maximum Temperature is developed at the center portion of the neck, which is the critical point. From the temperature graph, it can be observed that the increase in temperature is linear. This means, the temperature in the workpiece (neck portion) increases with an increase in displacement.
• The maximum deformation of the workpiece is 18.003 which matches the given displacement value.

Torsion Test

• For the given angular displacement, failure has occurred in the workpiece. The maximum shear stress experienced by the workpiece is 373.45MPa and Max equivalent stress is 649.35 MPa.
• As in tension test, the temperature is a linear function of the displacement and maximum occurs at the point of fracture.

Animation:

Tension Test

Equivalent Stress- https://youtu.be/XDmbH5OPu-c

Total Deformation- https://youtu.be/4GgQ9cYfc3M

Temperature- https://youtu.be/2q1qeY-7veM

Torsion Test

Equivalent stress- https://youtu.be/dVxnrVOfUkM

Total Deformation- https://youtu.be/AuUJF1d7llk

Temperature- https://youtu.be/ZpNycwWeunY