Positive Energy Error - R66 Rollover simulation

Moh Arian
Moh Arian New Altair Community Member
edited February 2022 in Community Q&A

Hi there,

I've been trying to do a Rollover simulation according to R66. I've calculated the impact velocity and implemented it as an initial condition.

The energy diagram I'm getting overshoots a little bit after the impact. 

I've been investigating the Kinetic and Internal Energy curves to find the parts with highest such energies and making improvements along the way. so the energy diagrams have improved a lot since I started. Yet, there's this overshoot that happens a little while after the impact that I have no idea about!

Additional info on the model:

  • I have added mass on pillars (to take passenger masses into account).
  • There are a number of components modeled as Point Mass and connected to the structure using RBODY.
  • The velocity contour is attached (GIF). I see extreme velocity increase in some areas after impact.
  • Ground is a Rigid Wall (RWALL).
  • I used DYREL, the results improved a bit.

 

I appreciate your comments or tips on this.

=====================================================================

Global Parameters:

image

Internal Energy (IE):

image

Kinetic Energy (KE):

image

Total Energy (TE):

image

Velocity Contour:

image

High Total Energy Components:

image

Tagged:

Answers

  • Rogerio Nakano_21179
    Rogerio Nakano_21179 New Altair Community Member
    edited February 2022

    Hi

    Please use TTE for the energy balance checking.

    • TER: Rotational total energy: TER=IE+KE+RKE
    • TTE: Translational total energy: TTE=IE+KE+RKE+CE+HE

    TTE does not include external work.

     

    Are you using/INIVEL for the velocity or /INIVEL/AXIS?

    Before the impact on the ground , the structure may be in rotation , then /INIVEL/AXIS may help.

     

    Hope this is helpful.

     

  • Moh Arian
    Moh Arian New Altair Community Member
    edited February 2022

    Hi Rogerio,

    Thanks for your reply. 

    I actually plot "DTE" which takes External Force Work in.

    Currently, I implement the initial velocity via /INVEL. I'm going to try with /INIVEL/AXIS too.

    I have an idea about why the internal energies take off drastically, but I can't understand why the kinetic energy takes off almost at the end.

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