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What is the difference between an ‘Alpha’ and ‘LCS Rotation’ of a 1D member?

Definition

Both ‘Alpha’ and ‘LCS Rotation’ are properties of a 1D member, which allow to input an angle in [deg] to define a rotation of the 1D member’s cross-section around itself (around its local x axis).

  • ‘Alfa [deg]’ is available as well in a 2D as a 3D environment.

Entering a value here has the following result:
The cross-section is rotated around the local x axis of the 1D member, but the LCS isn’t. So the direction of the local y an z axes doesn’t change.

  • ‘LCS-rotatie [deg]’ is only available in a 3D environment (Frame XYZ or General XYZ).

Entering a value here has the following result:
The cross-section as well as the LCS is rotated around the local x axis of the 1D member.

Remark: LCS stands for Local Co-ordinate System.

 

Example

The example consists of 3 beams with the same cross-section. Their LCS is shown by activating the View Parameters.

  • Beam B2 (in the middle) is the original one, with Alpha and LCS Rotation both = 0 deg.
  • For Beam B1 (at the left) Alpha = 90 deg, while for Beam B3 (at the right) LCS Rotation = 90 deg.

Reference number: 
ESA1105
Software: 
FAQ Category: 
Modeller
Access Type: 
Free User