Difference inertia relief and transient analysis. I need to solve this…

- August 25, 2021 at 12:32 pm
  
  ReadyDieFurkan
  Subscriber
  
  Is there any difference, why don't we use support in transient analysis, can anyone help?
- August 25, 2021 at 12:45 pm
  
  peteroznewman
  Subscriber
  
  Inertia Relief is a technique in which the applied forces and torques are balanced by inertial forces induced by an acceleration field. This is a Statics solution. Rigid body motion is zeroed out during the computation.
  Transient Structural also computes accelerations to balance applied forces and torques, but rigid body motion is also computed. In Transient Structural, you want to see the rigid body motion as well as the deformation of the body. If you are only interested in deformation and don't want to see any rigid body motion, then you would use a Statics solution with Inertia Relief.
- August 25, 2021 at 1:01 pm
  
  ReadyDieFurkan
  Subscriber
  
  Thank you very much, this might be the answer I was looking for.
- August 27, 2021 at 2:43 pm
  
  ReadyDieFurkan
  Subscriber
  
  . can you also please tell me that if it is not required to apply any supports to the transient model, then why won't it make the stiffness matrix singular? And why won't I see a rigid body motion error (like pivot) like I do in the static structural?
- August 27, 2021 at 5:54 pm
  
  peteroznewman
  Subscriber
  
  Static Structural is solving the matrix equation: [K]{u} = {F} and during assembly of the stiffness matrix [K], if the supports are not present, the matrix is singular and there is no solution.
  Transient Structural is integrating over time a different equation: [M]{a(t)} + [C]{v(t)} + [K]{u(t)} = {F(t)} and in this equation, you can have zero stiffness and the equation reduces to {F(t)} = [M]{a(t)} if you ignore the damping matrix.