Hello
In theory, when 2 parts are assembled by pre-stressed bolts, the bolt tension value is found thanks to the tightening torque and the coefficient of friction.
I find this value in simulation at the level of the bolt connector results in the axial force.
However, still in theory, as soon as the assembled parts are subjected to a service force, 2 phenomena can occur:
1) The working force is less than the clamping force (the parts remain in contact) - The force in the screws remains equal to the pre-stressing force created during assembly
2) The working force exceeds the clamping force (the parts come off) - The force in the screws is greater than the prestressing force of the delta between the 2 values
However, in simulation, the result given in the bolt connectors is always the sum of the 2 forces whatever the case ? (Let F = Clamping Force + Working Force)
Thank you for sharing your experience with me on this topic.
Hello Arles 62
It's normal
Be logical to the end ;-)
You say ( (2 parts are assembled by pre-stressed bolts )) which means that you give SW simul the information for torque tightening and coefficient of friction
Then you say: The working force exceeds the clamping force (the parts come off) - The force in the screws is greater than the prestressing force.
Except that since you don't give this value, SW can't guess it. On the other hand, if you do two simulations and you exaggerate the values in the second simulation, you will see in the results that you have exceeded the set value.
Any proportion keep it is as if you were saying instead of using the torque wrench to have the tightening within the standards; I put a 3 meter extension tube at the end of the key and how weird the bolts are popping. In other words, if the parts exceed the set point, it means that the number of bolts is insufficient and that's it!
SW reasons with the values of a torque wrench for one bolt: if the values don't hold, you have to put two or more bolts, but solidworks will just tell you that you are beyond the limits without suggesting the number of additional bolts.
Clearly it doesn't get wet ;-) ;-)
Kind regards
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Hello Zozo_mp,
Thank you for your message but it does not answer the question I asked at all. :-( Or I didn't understand...
Regardless of the value of the force exerted on the workpiece, the connector adds the value to the tension (contrary to the principle of clamping, see attached image)
To be clearer: Example, part tightened with a screw H M 20 torque of 640N.m without any other effort (result connector bolt of about 160000 N so ok)
If I put a force of 100000 N in the assembly, in theory the force in the screw remains at 16t because it does not exceed the clamping force. In the result, Simulation indicates a force of 26 t!!
And if I put an effort of 200000 N, same result of 36t.
I hope that this clarification can provide me with an answer, cordially.
principe_tension_vis.jpg
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OOooops I hadn't understood the question actually.
Kind regards
Good evening Arles62
Can you post your example by attaching the result of the simulation.
What version of SW do you have??
Kind regards
Hello Zozo,
I'm using Solidworks 2018 SP5.0.
Attached is a simple model (2 plates connected by 2 bolts) doing the calculation without and with the load on the round to compare the results
at the bolt connectors.
To talk about it again, cordially.
test-2-plaques.zip
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