What will be the appropriate load and boundary conditions for motorcycle front frame?
What will be the appropriate load and boundary conditions for motorcycle front frame?
(OP)
I am determined to find out the stress level at front frame of motorcycle in worst case scenario. I have prepare two model. One is MBD FLEX body model and another is FEA 1_D element model.
Geometry of Front Frame of motorcycle
MBD FLEX Model

MBD FLEX MODEL gif
https://res.cloudinary.com/engineering-com/video/upload/v1649136545/tips/mbd_gif_i640vs.mp4
FEA MODEL

From Flex MBD model, I came to know that maximum von misses stress are in the front frame's neck area. I have checked hot spot stress value. It is around 534 Mpa at neck area. I cannot trust this stress level blindly. So I decided to make FEA model using line element( I think line element is the best for this kind of geometry).But the problem is How do I apply constraints and loads in my model?. I have applied constraints in the head tube and loads in the suspension mount and swing-arm pivot points. I don't have much confidence in applying such B.C. What would be the accurate boundary condition in my case? Should I include inertial relief method for this ?
Geometry of Front Frame of motorcycle

MBD FLEX Model

MBD FLEX MODEL gif
https://res.cloudinary.com/engineering-com/video/upload/v1649136545/tips/mbd_gif_i640vs.mp4
FEA MODEL

From Flex MBD model, I came to know that maximum von misses stress are in the front frame's neck area. I have checked hot spot stress value. It is around 534 Mpa at neck area. I cannot trust this stress level blindly. So I decided to make FEA model using line element( I think line element is the best for this kind of geometry).But the problem is How do I apply constraints and loads in my model?. I have applied constraints in the head tube and loads in the suspension mount and swing-arm pivot points. I don't have much confidence in applying such B.C. What would be the accurate boundary condition in my case? Should I include inertial relief method for this ?
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
Is this some kind of school assignment or something you do out of personal interest? The reason I ask is because I expect a professional motorcycle designer would have that type of data. I suspect that the data should be based, at least to some extent, on test data.
Thomas
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
Thank you!
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
IMO applying directional fixity/use of symmetry BC's instead of completely fixing things would be way to go since motorcycle is dynamic body moving in the space coordinates. For conservative calculation purpose, I am not sure though, you can apply fixity at some points like you applied at front. But then you would have to deal with peak stresses which I would guess you need to compare with actual test data and come to conclusion.
Have a look at "Fundamental of vehicle dynamics by Gillespie" for forces acting on vehicle and then may be you can translate that into required boundary conditions.
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
A possible solution might be to use the ADAMS forces. Then the frame should be in equilibrium. And Inertia relief should help in managing the the constraints.
I have never analyzed a motorcycle frame but I suspect that this model woult be made with shell elements. I think that would give a better description of the joints. But that is just me guessing
Thomas
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
Thank you!
RE: What will be the appropriate load and boundary conditions for motorcycle front frame?
Your best bet is to rely on the available information in research papers and engineering judgment. I think its sufficient for the personal interest analysis.