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#26 2020-05-12 17:22:57

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Friction force depending on the timestep

here i hv attach sepaerate mesh files.
compound them.


Attachments:
Mesh_1.med, Size: 349.17 KiB, Downloads: 159

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#27 2020-05-12 17:24:00

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Friction force depending on the timestep

i hv define contact face as you have done.

i hv gone through your png.

what is p ----in geometry

what changes you suggest in my .comm file. how to strictly maintain centre distance between gears.

to apply torque i tried defining 0D element and LIasione Solid with Driven Gear,,,but gives Singaluraity Error because of Node on 0D element.

Last edited by sameer21101970 (2020-05-12 17:39:45)


Attachments:
Mesh_2.med, Size: 297.27 KiB, Downloads: 162

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#28 2020-05-12 18:44:24

mib
Member
Registered: 2019-11-10
Posts: 88

Re: Friction force depending on the timestep

in my case p is a shaft.

Sameer,

please, give me the files. STEP of geometry of worm and wheel.

i will try to do a study

:-)

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#29 2020-05-13 06:03:36

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Friction force depending on the timestep

ok. see attachment.

we can raise bug to code-aster.
Torque has to be applied to PCD of Gear.
And Code Aster doesnot allow defining 0D Element with Liasione Solid to apply torque , in contact analysis.

Hope, somebody from code aster is reading this.


Attachments:
Worm Gear.stp, Size: 1.83 MiB, Downloads: 149

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#30 2020-05-13 06:04:44

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Friction force depending on the timestep

ref. attach


Attachments:
Worm wheel.stp, Size: 1.39 MiB, Downloads: 150

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#31 2020-05-13 07:15:14

mib
Member
Registered: 2019-11-10
Posts: 88

Re: Friction force depending on the timestep

a possible reason because the solver don't converge ( see attachment)

is it a grab cad file?

:-)


Attachments:
Immagine.jpg, Size: 200.46 KiB, Downloads: 133

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#32 2020-05-13 07:34:23

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Friction force depending on the timestep

solver do converge in AUTO mode. But the Driven Gear shifts in DOF axis. Say DY is 0.0, Gear tries to shifts in DX, DZ. This changes centre distance and thus your torque data goes wrong...Reaction Force goes wrong.
yes it is grabcad file
i am using astk 14.4

Last edited by sameer21101970 (2020-05-13 07:53:04)

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#33 2020-05-13 07:44:31

mib
Member
Registered: 2019-11-10
Posts: 88

Re: Friction force depending on the timestep

well

probably converge because density mesh is low and it don't compenetrate

can you give me a video of paravis time step evolution? :-)

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#34 2020-05-13 08:05:25

mib
Member
Registered: 2019-11-10
Posts: 88

Re: Friction force depending on the timestep

see attachment

here you didn't block DZ DOF of wheel


Attachments:
here you didn't block DZ DOF of wheel.jpg, Size: 212.93 KiB, Downloads: 119

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#35 2020-05-13 08:09:23

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Friction force depending on the timestep

ref attachment

cannot upload video file size 14mb. sending screenshots


Attachments:
Screenshot from 2020-05-13 12-38-48.png, Size: 552.11 KiB, Downloads: 115

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#36 2020-05-13 08:11:39

mib
Member
Registered: 2019-11-10
Posts: 88

Re: Friction force depending on the timestep

Sameer,

are you with us????

:-)

i think which the reason of axis motion is which you don't blocked DZ DOF of wheel :-)


Attachments:
here you didn't block DZ DOF of wheel.jpg, Size: 212.93 KiB, Downloads: 120

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#37 2020-05-13 08:12:45

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Friction force depending on the timestep

i had block DZ =0.0, but DX is Open for movement. if DX=0.0 is also block, Wheel stops Rotation.


Attachments:
Screenshot from 2020-05-13 12-42-22.png, Size: 546.01 KiB, Downloads: 111

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#38 2020-05-13 08:17:00

mib
Member
Registered: 2019-11-10
Posts: 88

Re: Friction force depending on the timestep

if you introduce an auxiliary shaft in contact with the wheel the axsis distance will be the same

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#39 2020-05-13 08:24:06

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Friction force depending on the timestep

auxillary shaft will also move its centre to Free Axis Say DX on wheel.

you can run at your end, i have tried many options. even Giving Velocity by Rotation Command which allows Centre Defination.
Also, Applied Opposite Pressure in DZ direction to both gears.

We Mech Engineers need reliable solution from code aster.
And Code Aster has to allow Node, Element0, Liasione Solid to wheel without Singaluraity error, when contact analysis is done. As such we have to define Weak Spring additional to run Contact Analysis.
That is my observation.

Last edited by sameer21101970 (2020-05-13 08:30:13)

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#40 2020-05-13 17:40:26

mib
Member
Registered: 2019-11-10
Posts: 88

Re: Friction force depending on the timestep

@ Sameer

for me the problem is which in grabcad there isn't good geometry about worm and gear.

see this ( copy and paste in your browser)  :

youtube.com/watch?v=sEOdBsPem6k

if the pairing is right there should be no problems.

:-)

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#41 2020-05-13 18:10:50

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Friction force depending on the timestep

i think if torque is applied at pcd on driven gear will solve the problem. code aster at present doesnot allow 0D element with weak spring.

if anyone knows how both 0D +liasione solid and weak spring can be incorporated, please reply.

Mr. Konrayo views are welcome.

Last edited by sameer21101970 (2020-05-13 18:17:06)

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#42 2020-05-13 20:05:23

mib
Member
Registered: 2019-11-10
Posts: 88

Re: Friction force depending on the timestep

sameer21101970 wrote:

i think if torque is applied at pcd on driven gear will solve the problem. code aster at present doesnot allow 0D element with weak spring.

if anyone knows how both 0D +liasione solid and weak spring can be incorporated, please reply.

Mr. Konrayo views are welcome.

RIGHT.

I also think that the game between the teeth induces rebounds

:-)

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#43 2020-05-14 07:04:45

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Friction force depending on the timestep

there should not be any rebound of teeth when torque is applied. your observation is right mr. mib.

Can we Raise BUG or Write to CodeAster. How to do it. Is anybody from CodeAster Reading.

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