Contact Mechanics - Friction Test

Numerical methods and mathematical models of Elmer
maike151
Posts: 41
Joined: 10 May 2019, 10:00
Antispam: Yes
Location: Cologne, Germany

Re: Contact Mechanics - Friction Test

Post by maike151 »

I did the very same thing with Friction Contact = Logical True instead of Slide Contact = Logical True and get the same results, so I guess it didn't work because of the Normalforce instead of Displacement 3 to simulate the Normal Force.
raback
Site Admin
Posts: 3746
Joined: 22 Aug 2009, 11:57
Antispam: Yes
Location: Espoo, Finland
Contact:

Re: Contact Mechanics - Friction Test

Post by raback »

Hi,

This seems like a very relevant thread which I've missed during my vacation and travels. I could have a look but it is somewhat difficult to read through the messages and see how far you came. Perhaps somebody could describe the current status (with case provided) and/or contact me with personal message.

Are you looking for dynamic (sliding) friction, or mixed dynamic/static friction (always transient)?

-Peter
kevinarden
Posts: 651
Joined: 25 Jan 2019, 01:28
Antispam: Yes

Re: Contact Mechanics - Friction Test

Post by kevinarden »

Peter,
It started out as trying to drag a cube across a surface with the weight of the cube being the normal force and the friction force should be Fs = Fn * mu however that was not the case. Then tried to load the cube to produce a normal force, with normal load only, it gave correct results, but not when sliding. Finally, based on some test cases, used enforced displacements to press the cube into the surface and drag it. This produced good results. However if loads are used instead of enforce displacements, either it isn't working or it is diverging.

There is a test case two posts back called blunt.zip with enforced displacement.

Kevin
kevinarden
Posts: 651
Joined: 25 Jan 2019, 01:28
Antispam: Yes

Re: Contact Mechanics - Friction Test

Post by kevinarden »

plate model mesh
https://github.com/mrkearden/platecontact_elmer

With a normal load of 10 and no motion, the normal load equals 10, the slip load equals 6.
normal_load_no_motion.png
(31.63 KiB) Not downloaded yet
With a normal load of 10 and the plate is pulled along the surface, the normal load and slip load is very high.
normal_load_no_motion.png
(31.63 KiB) Not downloaded yet
slip_load_with_motion.png
(33.99 KiB) Not downloaded yet
Attachments
normal_load_with_motion.png
(32.09 KiB) Not downloaded yet
Post Reply