torque application in hexagonal bolt

[ksarita20]

hi all ,


I have to apply a torque of 1230 inch-lb on the hexagonal faces parallel to axis of the shaft. the other end surface of the the threaded bolt is fixed in all degrees of freedom. THis is my problem.


i have gone through the forums that discussed about the torque application in pro/mechanica and i felt that applying this load as a "moment" with "total load at a point option" seemed right.


So i created a point on the Z-axis( axis of the shaft) and applied the moment in theta direction( i used cylindrical co-ordinates). But the pro/e is prompting saying that the point cannot be on the z-axis.


though it seemed simple thisreally confused me.


So can any one please guide me regarding this.


Can i do the same as simply applying a force on these surfaces with "total load per unit area" option. If so how will the magnitude of my force change.


i will really appreciate if some one can guide me.


thanks in advance


eagerly waiting for reply.


Sari

 

[Luis Aguirre]

Sari,





The moment must be applied in the Z-axis not in the theta-axis. I think that is the problem that you have.








Luis

 

[burnsp]

Here's what I do for torque on a shaft...
<?:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" />

1. 
   <LI =Msonormal style="MARGIN: 0in 0in 0pt; mso-layout-grid-align: none; mso-list: l0 level1 lfo1; tab-stops: list .5in">Create a cylindrical coord system along the axis of the shaft. The 'z' axis should be the axis of the shaft</LI>
   <LI =Msonormal style="MARGIN: 0in 0in 0pt; mso-layout-grid-align: none; mso-list: l0 level1 lfo1; tab-stops: list .5in">Create a surface load using the top surface of the shaft and the cyl coord system. The distribution is Force Per Unit Area, Uniform. </LI>
   <LI =Msonormal style="MARGIN: 0in 0in 0pt; mso-layout-grid-align: none; mso-list: l0 level1 lfo1; tab-stops: list .5in">Set your theta force value to some desired force and OK to complete. All other values should be zero </LI>
   <LI =Msonormal style="MARGIN: 0in 0in 0pt; mso-layout-grid-align: none; mso-list: l0 level1 lfo1; tab-stops: list .5in">Now review the total load and check the actual torque (moment) applied to the shaft. Do this as follows

 

[ksarita20]

Thanks for your immediate reply.


Luis, i tried in all the directions but i get the same error. i dont understand why.


The error says that the point for "the total load at a point" load may not lie on the z-axis of the associated cylindrical co-ordinate system.


So what can be the problem

burnsp, i actually saw your answer in other forums, thats how i came this method. But the surface on which i am apply the load is parallel to the axis of the shaft. So will this make any difference.


PLease help me.


thanks once again


Sari

 

[burnsp]

Are you trying to determine the stress around the hexagonal faces? If so, then you need to model thefemale coupling (with appropriate clearances) on the shaft and analyze the assembly. In this case you can fix the other end of the shaft and apply the torque to the opposite face of the coupling. You'll probably need some contact analysis- try assigning contacts between the coupling surfaces and the hexagonal faces. Maybe someone else can chime in on the use of contact surfaces - I'm not real familiar with them.


If you just need torque on the shaft, apply the torque to the face of the shaft andnot tothe hexagonal faces.


Make sure you create a cyl coord system and assign the z-axis to the axis of the shaft and then select this coord system when assigning loads.

 

[ksarita20]

Thanks for you reply, Mr. Burnsp.


I have only a single part, so i dont need to use contact analysis. And in my application, the hexagonal headed shat is being tightened using a wrench so the torque is applied on to the vertical faces of the hexagon. the top face of the hexagon is not exposed to any load.


So how do i generate this in pro/e simulation.


I hope i am clear.


thanks in advance.


Sari

 

[burnsp]

If you're only interested in the stresses further down the shaft (outside the hex effect), then apply the load to the face of the shaft as we've discussed and ignore (remove) the hex.


If you're interested in the stresses around the hex, then you need to accurately simulate the way the load is applied to the hex and this is very much dependent on the wrench.I would try to simply (but accurately) model thewrench andassembleit to the shaft. You can then apply a load to the wrench at the appropriate distance and direction. You'll of course have to constrain the wrench - fix it everywhere except rotation about the z axis. You'll also need to fix the other end of the shaft. I'veused this method witha screwdrivertwisting a screw headwith fairly good success - although I was applying a torque to the normal face of the screwdriver as opposed to a load at some distance.


Any other ideas out there? Good luck and let us know how it works out.


-Paul

 

[ksarita20]

thank you very much Mr. Paul. I also worked out the problem in similar way, i designed a small wrench.


And i think the results are pretty ok. i need to still check the results.


But thank you verymuch .


Sari

 

[burnsp]

I'm glad it worked out. You can checkthe resultsby applyingtorque to the shaft face and compare the resulting stresses/displacements to those obtained by applying the torque with the wrench. Further down the shaft, they should be the same if the torques are equivalent.

 

[ksarita20]

Thanks, i will do that.


Sari