Modifying rack and pinion steering system hardpoints... 1

[Fariborz90808888]

hi

i have modified steering a default Adams/car steering model and i get a steering test in a front suspension model...

the parameters are normal, the suspension has no problems when i tested it separately.

when i modify intermediate shafts hardpoints to the location of the vehicle model, the Adams suspension analysis simulation encounters problems and the adams/car model closes and the window shows "Not responding"... so i can't see where the error happens...

but i know it happens when i modify the intermediate rear and forward shafts hardpoint locations...

also the pinion pivot itself encounters a warning when i change its hardpoint location but the simulation completes...

can you help me through this???

it is annoying. is there another way like changing the joints in the template so the steering can steer to the value of the angle that i want???

appreciate your help

 

[Fariborz90808888]

these are my hardpoints:

is a joint replacement necessary???

 

[Fariborz90808888]

also the excel file for a quick copy paste:

 

[GregLocock]

Firstly we do have an ADAMS forum here

https://www.eng-tips.com/threadminder.cfm?pid=823

Secondly you've got rather an incredible angle on your rear intermediate shaft joint, and your steering wheel is outboard of the ITR which is novel. Thirdly you've got a horrible angle on the pinion to ISF

Fourthly i don't use Car so i don't know what the second hp is supposed to be.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Fariborz90808888]

thanks a lot for responding GregLocock

but how can it be solved?

can it be solved only by replacing joints or moving the location of the hardpoints?

 

[GregLocock]

You might make it work if you replace all the Hookes joints with CV joints I suppose. I suggest you start with the running model, then move the hp half way to your proposed positions, and see if that runs.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Fariborz90808888]

thanks a lot

It worked . I replaced hooke joints with convel joints and it worked.

one other question... how similar the hooke and convel joint performances are??? do they have similar effects on the system and will the covel joint do the same job as the real steering systems?

 

[cibachrome]

The fundamental problem is the phase angle on the I-Shaft is WAY off of a solvable geometry. That is why the cv joint works. You have a severe case of "lumpy steering" ! If the pinion and the end of the column are co-linear, you can usually find an appropriate phase angle for the I-shaft.

 

[GregLocock]

Phasing of Hookes joints is a handy tool for giving different on centre to off centre steering ratios, particularly now that we are using fewer turns lock to lock. CV joints remove that tuning option, which is good and bad. It's good in that people often get it wrong, introducing asymmetries in response. It's bad in that it is a useful option. CV joints are more expensive, tend to be bigger, hence harder to package, and have their own articulation limits. I suspect they'd have more friction, which is a bad thing to have in your steering column. I've never used them.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Fariborz90808888]

thanks a lot GregLocock and cibachrome

great job in making this discussion crystal clear.

appreciate your help