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Problems about calculating gears contact force

Altair Forum User

Hi, I'm a new student in using Hyperworks products. Now I'm trying to use Hypercrash to solve the contact force of a pair of gears. and I set up BCs, imposed velocity, and concentrated load.
BCs, only rotation Z has DOF
imposed velocity, function, from 0 to 100 ms, accelarate from 0 to 0.012566. then keep 0.012566 to 200ms.
concentrated load, has a 0.4 N/mm load from 0 to 100 ms.
using Type 7 contact.
unit system kN, mm, ms, kg, User profile Radioss V10.

when I use radioss to solve, I could run this with no errors.
but after I change the imposed velocity to a different value, like 2(0.012566->2), or change the concentrated load, to 10, there are more or less error pop out.
such as, Energy limit reached, Mass limit reached. or time step less or equal to zero.
I know this error shows up because of the engine files setting Card DT/NODA/CST, and maybe the setting in contact setting.I searched on the internet, and see some the errors could be fixed by increasing Stiffness, or Gap. But I tried it and nothing change, Could anyone teach me how to make it right?

it's really nice to have any replies . thanks for advance to everyone.

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Altair Forum User

Hi,

Could you please let me know the following:

1) What type of the elements are you using (solid or shell)?
2) if solid, brick elements or tetra? if brick elements, what is the element formulation?
can you check if there is any initial penetration in your model?
3) Have you tried changing the time step?
4)As you said there is contact between two components, can you move one part physically by some distance (say by 0.5 or 1mm) and check if you still get the error?

Altair Forum User

Thanks for your reply first.
here is the supplement
1) I used solid elements.

2) brick elements, formulation: 24: HEPH 8-node solid element. There are some penetrations when I used hypercrash Quality-> Check All Solver Contact Interface.
But when I use Hypermesh , Tool-> penetration , there is no penetration, And I used Inacti=5 Gap is variable with time.

3) I changed time step from 1.5^-4 to 1.5^-5 or 1.5^-6 in DT/NODA/CST, when the warning message shows up:
WARNING INTERFACE 1
NODE 37983 DE-ACTIVATED FROM INTERFACE
Energy and Mass error limit reached.

4)I tried moving one part by 0.5mm, and there is no any penetrations or intersections in hypermesh or hypercrash both. but still can't cal in Radioss.

I've uploaded the files to the dropbox in your signature, name GearContact. Thanks again

Altair Forum User

Setting a Gapmin of 0.3 in interface worked without any error termination. also, I re-created the interface by assuming one gear as master and the other as slave.

you can refer to the link below on how the interface stiffness works:

http://www.altairhyperworks.com/hwhelp/Altair/hw12.0/help/hwsolvers/hwsolvers.aspx?general_purpose_interface_type_7.htm

Altair Forum User

hi, after I did what you said, setting Gapmin as 0.3, re-created the interface without the self impact checkbox checked , and chose the small gear as master, the big one as slave. The same problem stiil happened. Did you change the time step or anything else?please let me know.

really appreciate your help.

I tried changing time step too, it's still the same.
Could you please send me the changed file? my email address is: xxxxxx@gmail.com
thank you.