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CosmosWorks 2005 Shaft Analysis

Japazo

New member
Hello everyone!

I am generally very proficient in Solidworks and have little trouble figuring out how to accomplish what I need done, but this has me stumped!

I am performing an analysis of a shaft for a baja car which keeps breaking at a known area. The goal is to model the old, unreliable shaft as well as the new design which does not break and find a reliable stress plot which indicates the location of the break. Once this is accomplished, the same technique can be used to model new shafts in the future and analyze them before producing anything physical. Below is a screenshot of a similar axle.

View attachment 5865

My problem occurs when defining constraints and loads. There is a bearing surface on the first cylindrical surface (blue) as you move away from the center of the shaft. There is a force (from the wheels) on the second cylindrical surface (green) as you move in from the ends of the shaft. I have tried restraining the part in several different ways but the result is either that the center cylinder section of the shaft is completely fixed (inaccurate) or the stresses in the part are unrealistic and do not represent the way the shaft is breaking. I understand that there are many things to consider aside from static loading but I want to nail this technique down before moving on to fatigue and vibrations.

I applied a bearing load to the bearing surfaces and a static load to the wheel surfaces. I think my problem occurs when I try to apply a restraint. As I said before, applying any kind of restraint to the center of the shaft results in that section not bending under load, which makes sense. Applying a restraint to any other part of the shaft results in an unrealistic deformation in other ways.

Is there a way to create a restraint in CW 2005 that will allow the entire shaft to bend as it would in real life? Does altering the tolerances of restraints in the correct manner allow for this type of result? Any help would be greatly appreciated. Thanks ahead of time!
 
Japazo,


So, you have a radial load on the green surfaces and a bearing constraint on the blue?


Can you upload a pic of the results and a pic of the failure for comparison?


Perhaps you could model the bearings (simply) and replace the bearing constraint with "no penetration" contact elements... I'm confident we can get this figured out quickly.


Jim
http://www.linkedin.com/in/shawengineering
 

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