Transient Structural analysis?

- November 7, 2018 at 1:48 pm
  
  Vanderbezi
  Subscriber
  
  Hello,
  
  I have a problem as i am new to Ansys. I am doing an Analysis of a crankschaft to determine its torsional stiffness under different boundary conditions.
  
  is the "Transient structural analysis" the right analysis if i want to simulate the crankshafts working conditions for a period of 720° with all the forces from the pistons? or are other analysis types like "dynamic analysis" more appropriate for this use?
  
  regards,
  
  Bezi
- November 7, 2018 at 2:53 pm
  
  peteroznewman
  Subscriber
  
  Hello Vanderbezi,
  
  If you are new to ANSYS, I recommend you begin with a Static Structural analysis. You can apply the peak force from a piston onto the bearing face of the crankshaft at the correct angle, and repeat this for each piston. The end of the crankshaft that goes into the transmission would have a fixed rotation for the reaction torque to be developed.
  
  Regards,
  Peter
- November 7, 2018 at 7:42 pm
  
  Vanderbezi
  Subscriber
  
  Hello Peter,
  
  thank you for your response. a few questions furthermore are:
  
  1- Do you mean with "fixed rotation": DOF = 0 ?
  
  2- If I allow only rotation on 1 axis for the main bearings(Journals) and set the other 5 dof to 0, would that be considered over-constraining the model for the stiffness analysis?
  
  Regards,
  
  Vanderbezi
- November 7, 2018 at 9:55 pm
  
  peteroznewman
  Subscriber
  
  Hello Vanderbezi,
  
  You can use two Bearing Supports to hold the crankshaft at the bearing faces that connect it to the engine block. Two bearings spaced along the crankshaft take away 4 DOF.
  
  If you create a Remote Displacement on the end of the crankshaft that connects to the gearbox, you can set the axial displacement to zero and the rotation about the axis to zero, so with those 2 DOF added to the 4 DOF from the bearings, you have an exactly constrained crankshaft.
  
  Regards,
  Peter
- November 7, 2018 at 10:11 pm
  
  Vanderbezi
  Subscriber
  
  Hello Peter,
  
  thank you for your answers. one last question:
  
  in a transient analysis with a remote displacement at the gearbox end with the angle at given time steps. and with the loads on the crankschaft(right angle and force). is that then considered over-constraining the model?
  
  regards,
  
  Bezi
- February 25, 2019 at 9:03 pm
  
  peteroznewman
  Subscriber
  
  No, that is not overconstrained.

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