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[Psn83]

Good morning all,

I am trying to compare Ansys results to hand calculations for Shear Stress and Maximum Shear Stress for a simple cantilever beam (10mm x 10mm x 100mm) with a 1N load at the end face. I have modeled the solid beam in SpaceClaim as an extrusion of a rectangle so I am not using the predefined beams built in SpaceClaim.

At the fixed support, I ended up using remote displacement to have the option of deformable behavior on because when using the standard fixed support I get singularity points that mess up the results.

The support and the load has been applied to the faces at each end of the solid beam (normal to the longitudinal axis Y)

The hand calculation for the Shear Stress is just the Load/Area and for the Maximum Shear Stress is (3/2)*Load/Area. 

I get the Von Mises Stress spot on but for the Shear Stress and Maximum Shear Stress I get odd results. If you could help me understand what is going on it would be very much appreciated.

Please see pictures below.

Best Regards,

Pablo

[Aniket]

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[Psn83]

Thanks Aniket,

Cheers,

Pablo

[Ashish Khemka]

Hi Pablo,

 

Please refer the following links for the stress calculations:

 

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v195/wb_sim/ds_Stress_Strain.html?q=maximum%20shear%20stress

 

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v195/wb_sim/ds_Maximum_Stress.html?q=maximum%20shear%20stress

 

Based on the last link, if you consider maximum stress = 0.6MPa and minimum stress ~ 0 then the maximum shear stress will be 0.5 x (0.6-0) = 0.3

Please see if this helps.

 

Thanks,

Ashish Khemka

 

 

[Psn83]

Hello Ashish,

Thanks for your message.

I am confused because I learned at Uni that the max Shear happens in the middle of the beam following the formula 3/2*F/A. Please see the image below.

 

Regards,
Pablo

[Ashish Khemka]

Hi Pablo, if you check the shear stress in XY direction at a cross-section, you will see the results in line with the analytical results (with minor deviation - FEA results being more realistic):

 

Hope this helps.

 

Regards.

Ashish Khemka

[Psn83]

Dear Ashish,

Thanks for your message.

The thing is that if we plot the maximum shear stress in Ansys then we get a completely different answer and the formula for maximum shear shows that it happens at the middle of the beam instead of what Ansys gets as Max. Shear. Therefore, that is my doubt, why do we get a completely different answer in Ansys when looking for maximum shear stress?

P.S. Sorry for my late reply.

Best Regards,
Pablo