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Help with bearing loads vs. force applied to an inner bore.

Question asked by Dustin Smith on Sep 14, 2017
Latest reply on Sep 15, 2017 by Bill McEachern

I am working on analyzing the stresses inside and around a connecting rod small end.  I am trying to verify my results and the different ways to apply a force to the small end.  Currently I am running a static analysis with fixing the big end with a split line, and am applying a total force of 17000N (tension) to the small end bearing surface.  I have attached three different scenarios with vastly different results.  The first is applying a "bearing load" directly to the surface in the Y direction, the second is applying just a force directly to the surface in the Y direction and the third is using an assembly with a wrist pin inserted into the bore and then applying the force to the pin with a no-penetration contact set(the third gives very similar results whether using a bearing load or a force). All there photos are scaled the same.  I would assume the bearing load to give higher stress concentrations due to the sine wave distribution but the results are vastly different.

 

My concern is how vastly different the "bearing loads" results are.  The stresses are much higher than my hand calculations are showing(they are similar to the other options).  Can anyone shed any light on this?  There is very little clearance(a few microns) between the wrist pin and connecting rod bore so I would assume the force would partially sinusoidal however theses results seem very dramatic. 

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