Simulation of powder compaction

[milov]

Hi, I am relatively new to Abaqus and have some problems regarding boundary conditions and steps in a powder compaction simulation I am trying to do.
My calculations constantly crash due to errors with the boundary conditions.
In principle I have 4 parts: the powder, a punch, a die around the powder and a bottom piece under the powder.
I would like to simulate the punch moving down and compressing the powder, but I am not sure how to define the steps and BC's to ensure the correct contact between all the surfaces.
I would appreciate any help.

Thanks

 

[Jlog50]

My advice would be to start with just two parts, using simplfied boundary conditions and materials. Establish any contact with displacement before switching over to load control. Then start adding the complexity bit by bit, that way if any errors occur along the way, you know what is causing the problem.

 

[Nileo2005]

Sounds like you need to encastre the die and the piece under the powder, and displacement BC the die. The powder can be held in my a gravity loading.

Jlog50,
Quick question about your response as it may be something I've been looking for. When you switch from displacement to force control, do you mean catching the current loading on the plate and ramping it from there? How would you know what magnitude to start the force application at?

 

[Jlog50]

Hi Nileo2005,

I deal with problems of components in contact and in order to establish equilbrium I very often need to apply a small displacement even if its a few microns (say in step 1), then I add my load (say in step 2). My force application is just what I my load is. I just need to make sure that my displacement does not does not exceed my deformation in step 2. After speaking with a techi at Simulia about this, he mentioned that its standard practice in contact mechanics simulations. I hope the makes sense.

 

[Nileo2005]

Ok. So you just make sure not to displace it enough to store any resistance (or at least minuscule amounts) on the force applicator. Primarily, you just need to make sure that you aren't forcing in displacement against a spring force greater than your desired application force, right? That makes sense. Didn't know if there was any special trick to it though. Thanks! Milov, sorry for the thread jack. I'm done now. Haha