unpredicted joint force behaviour

Question

unpredicted joint force behaviour

dkakth (Mechanical)

(OP)

8 Nov 15 12:03

Hello !

I have modeled a completely symmetric lift table (

), but when i simulate, I have interesting situation where there are joint forces only on the joints which are on left side of table (A, B, C and D) (

), whereas corresponding joints on the other side deliver zero. what causes this strange behavior ? I am attaching the *.cmd file if you wish to have an eye upon...

greetings ;)

http://files.engineering.com/getfile.aspx?folder=bcc144ba-f8df-4239-9ff1-1a

GregLocock (Automotive) · Answer 1 · 2015-11-09 08:03:57

I suspect that if you check the run time messages from the solver it says something like 'Read this carefully. Over constrained joints in model. The following degrees of freedom have been released...'

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

dkakth (Mechanical) · Answer 2 · 2015-11-09 09:50:50

indeed, but how can i have forces on each joint then

p.s. sorry - im new to MBD analysis...

GregLocock (Automotive) · Answer 3 · 2015-11-09 23:10:30

You need a better model. How does a real structure equalise the forces across a nominally symmetrical mechanism?

Incidentally who is mentoring/teaching you on MBD?

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

dkakth (Mechanical) · Answer 4 · 2015-11-14 03:17:37

Im self - educating :( Reading some books and thats all - if you can guide me to good videotutorials / books i will be grateful !!!

dkakth (Mechanical) · Answer 5 · 2015-11-14 04:34:57

...and once again - i want to monitor joint forces on both sides - if i add one more joint, im overconstrainting it - what should i do ?!

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