×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Spurious energy balance increase at the end of dynamic explicit analysis

Spurious energy balance increase at the end of dynamic explicit analysis

Spurious energy balance increase at the end of dynamic explicit analysis

(OP)
Hello fellow engineers!

This is my first time writing here, although I regularly consult some useful forum threads.
I face a quite strange issue with Abaqus Explicit. I am running a linear dynamic plane-strain analysis of a soil domain using CPE4R elements (1mx1m) and CINPE4 (infinite) elements to model the boundary conditions as you can see in the attached picture. A real earthquake record in terms of horizontal force is used as uniform input excitation at the base nodes (PGA=0.24g).



I use no material damping so far and I have used no fixed boundary conditions. The reason I'm running this analysis is to check the efficiency of the infinite elements in absorbing the seismic wave energy.
The problem arises when I plot the energy histories. As you can see, the dissipated energy accounts for almost the entire external work done by the seismic forces. However, the last three seconds consist of unexpected high frequency oscillations with increasing amplitude of the kinetic and strain energy, and also the artificial energy becomes noticeable (~10% of strain energy). As a result, the total energy balance starts to deviate from zero and becomes an increasing function of time. This obviously violates the conservation of energy law.




I've tried enhanced hourglass control to solve the issue but with no results.
Do you have any idea about what may cause this issue?
I would be grateful for any insight from more experienced people in Abaqus Explicit smile.






Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources