CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > General Forums > Structural Mechanics

Impact stress on the body

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 25, 2015, 21:37
Smile Impact stress on the body
  #1
New Member
 
Azif Ali
Join Date: Mar 2015
Posts: 2
Rep Power: 0
lkwarm is on a distinguished road
Software: ANSYS 15.0 Workbench
Application: Transient Structural analysis

I am trying to simulate impact stresses on 2 contacting bodies which are rotating about different axis. One of the body is assumed to be at constant rotational velocity and the other body is torsional spring loaded. Both the bodies come into contact and rebound and again come to contact.

My duration of interest is just 5 ms during which both the bodies come into contact thrice. The contact(frictional) formulation was done using pure penalty formulation. The simulation was successfully converged, but the results do not fall in the expected or experimental results range.

As the velocities and the contact stress obtained from the analysis are way higher than the experimental results i was thinking, this might be due to not including damping forces for the system. Using damping controls in analysis settings. Is it a right way to go forward with?.

Also high contact stress is the reason for high rebound velocity. Can you suggest me some method to reduce/ dampen the contact impact stress?.
lkwarm is offline   Reply With Quote

Old   March 30, 2015, 13:56
Default
  #2
siw
Senior Member
 
Stuart
Join Date: Jul 2009
Location: Portsmouth, England
Posts: 735
Rep Power: 25
siw will become famous soon enough
The total time of 5 ms is very short for implicit time integration FEA; e.g. Transient Structural in ANSYS Mechanical. Are you using adaptive time stepping or a constant timestep? Can you use explicit time integration in Workbench (i.e. ANSYS Explicit STR)? Then you can use Body Interactions for the collision rather than a non-linear Contact (NL contacts greatly slow down simulations), see http://www.ansys.com/Products/Simula...licit+Dynamics.
siw is offline   Reply With Quote

Old   March 30, 2015, 16:50
Default
  #3
New Member
 
Azif Ali
Join Date: Mar 2015
Posts: 2
Rep Power: 0
lkwarm is on a distinguished road
Thanks siw for your reply.. I know implicit scheme is really slow for the solution but I was unable to give nonlinear inertial loads in explicit.. So I went on to use implicit. I am not using automatic time stepping.. In order to reduce the simulation time I am using plane strain model. I have a different question here.

In plane strain models, what is the assumed thickness of the body. When I apply a load I can see the body accelerating, so there is an assumed thickness and hence mass for the assembly.. Thanks for your reply in advance
lkwarm is offline   Reply With Quote

Reply

Tags
contact stress, damping, dynamic transient, structural mechanics

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
6dof model - floating body flinde FLUENT 13 March 6, 2021 14:32
impact force (shear stress) by waterjet impingement herozhu Main CFD Forum 0 May 7, 2014 20:39
How to calculate body forcefor 2d wedge impact simulation khurrammtc FLUENT 0 August 14, 2012 02:11
shear stress scalar definitions? Novak Elliott CFX 0 April 6, 2003 01:45
What is the detail definition of wall shear stress zjm FLUENT 0 January 2, 2002 07:43


All times are GMT -4. The time now is 18:38.