Bearing Load Distribution Function?


#1

Need some help here. I’m looking to create a bearing load distribution on a cylindrical surface. Anybody good with code to help me create the proper function? Also, is there a way to ensure it is compression only? Meaning, when I select the face, I want the force to be applied only to the nodes in compression. Thing of a cable/rope/chain being pulled away from a ground anchor at some oblique angle… thanks!


#2

Hello @fastwayjim,

it is possible to create a bearing load on a cylindrical surface with help of the sin/cos functions. I made a very simple analysis of a car rim here https://www.simscale.com/projects/stadlerj/car-rim-structural-analysis/, where the load is applied only on the lower face. It is only a surface load, which means, that the force is only acting in one direction as specified. The function here is quite simple, since it is assumed, that the force is only dependent on one coordinate. But if you use the pressure BC and want the resultant to act on a specific angle, the formula is dependent on more than one coordinate and it gets much more complicated. So you could also model the cable/rope/chain as a hook and work with contact BC.

Best
Johannes


#3

Awesome, thanks @stadlerj!

Yes, I was thinking cosine, and yes I would like it to be at some oblique (“any”) angle. Perhaps Simscale could add this in!

In your case, did you strategically split the surfaces in CAD prior to import? Does the 0.133 refer to the mean diameter of the selected surfaces?


#4

Hello @fastwayjim,

please excuse my late answer.

I will forward your suggestion to the responsible person. Thanks for this! Your input is really appreciated.

Yes I did split up the CAD before the import. I researched the theory behind this problem and came to the conclusion, that the force is mainly distributed on this part of the wheel. This applies for car rims and I don’t know if it is generally applicable. The “0.133” stands for the y coordinate. The cosine function starts at y=-0.133 with a value of 0. The maximum is at y=0 and then it goes back to 0 when it reaches y=0.133.

Best
Johannes


#5

Hello,

I need help with this bearing load distribution for exactly the same application as you.

What I’ve found out is that the Distribution is of the from: Fo*sin(angle) (or cos(angle) if you want it to be rotated 90deg). But I’ve struggled to calculate Fo, I see you got a coefficient there is suppose thats you Fo. How did you calculated this with respect to the Total load?

Regards,
GF


#6

You want the integral of your function to equal the total load. Just visualize how your load function will be distributed among all of the nodes (based on their geometric location) and they all need to add to the total force applied.

Excel an be used, but Wolfram Alpha has a great online tool that does calculus (among many other awesome things). For example, for a total force of 100 lbs on a 2" diameter cylindrical hole, F0 = 59.42, as shown here: http://m.wolframalpha.com/input/?i=integrate+59.42+*+cos+x+dx+from+x%3D-1+to+1&x=0&y=0.

This method uses @stadlerj’s approach of splitting the cylinder in half, and applying this load to the surface on which the load is applied. Using my math, the cylindrical hole in question would need to be centered on the X-axis (assuming “x” is the independent variable).

You can double check your work in FEA by post-processing the reaction loads.

Does this make sense?


'Car Rim Structural Analysis' simulation project by stadlerj
#7

Hi @stadlerj Thank you for the resourceful simulation details, i just couldn’t understand how did you arrive at ‘57624’ and ‘y’ is a unknown in this function, how the solver interprets this function for ‘y’ value.? (the function: 57624cos(3.14/2y/0.133)

I also wanted to ask why do you find von mises stress and cauchy stress, since both the results are varying how do we know which stress to refer for operation condition.

Many thanks


#8

Hi @naveen_kumar!

Y in this case is the y-coordinate of the CAD model so it is known.

Crisp answer to your question related to von Mises and Cauchy:

  • Use the von Mises yield criterion to figure out if the material will fail (based on the three principal stresses)
  • The von Mises stress is a scalar that can be calculated from the Cauchy tensor
  • The Cauchy stress tensor in general only defines the stress at a point

Does that somehow cover the points you were asking for?

Best,

Jousef