Centrifugal force loading analysis, RFORCE, with OptiStruct

Rogerio Nakano_21179
Rogerio Nakano_21179 New Altair Community Member
edited February 2021 in Altair HyperWorks

Hi

 

In this article, I explore the usage of the Card RFORCE within OptiStruct.

 

With this card we can define a static loading condition that is related to centrifugal force field.

In my case, I am using just constant angular velocity, but RFORCE can be used as Exciting source as well.

In order to do that you can define the RFORCE as the EXCITEID field (Amplitude "A") of dynamic loads in RLOAD1, RLOAD2 , TLOAD1 and TLOAD2 Bulk Data Entries.

 

To illustrate the usage, I defined a simple disc that rotates at constant angular velocity.

 

The disc center is positioned at the global (X,Y,Z)=(0., 0., 0.)

And the disc is rotated +20.deg with regards the global axis Y.

Due to that, I created a local coordinate system, CORD1R, positioned at center, to be the reference of the vector of angular velocity.

Vector is normal to the disc surface; therefore, the components of rotation direction vector are (R1, R2, R3,) = (0. ,0., 1.) regarding the local coordinate system.

 image

In the model the material is linear elastic with parameters

  • Young Modulus = 210,000.MPa
  • Mass density = 7.9E-09 t/mm3
  • Poisson ratio = 0.29

 

And geometry and loading are:

  • Disc radius = 360.mm
  • Disc thickness = 3.6mm
  • Angular velocity = 100. rev/s = 100.*2*pi rad/s

 

The values of stresses and displacement of the disc under the loading conditions can be calculated by the following equations.

 image

Having this type of analytical solution was useful to verify the modeling approach and the results I got from the finite element analysis with OptiStruct.

 

With those parameters, the expected output values are:

Maximum radial stress = Maximum circumferential stress = 166.2MPa at the center

Maximum radial displacement = 0.1244mm at the maximum radial location

 

The following contour plots in HyperView illustrate the results of OptiStruct analysis.

 image

image

image

Spot-on!

 

I include my example model to this article, so you can modify and explore other options in the Card.

 

Let me know if this article were helpful to your applications.

And if there is also other topics that you would like to see here, please let me know

 

Regards

 

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