Good mornings to all,
My question is about the understanding of the "bolts" connector on simulation.
Indeed, I created a fixture with four M12 A2 stainless steel bolts, they all work in tension.
How is the bolt strength calculation performed. For example, if I apply a tightening torque of 74Nm, I get forces in the bolt axis of 31405 N and if I remove this torque, the force increases to 16053 N.
How the software uses the data provided to it.
Thank you for your answers.
Hello
Have you looked at the help topic about bolts in Simulation?
It's already quite complete:
http://help.solidworks.com/2014/French/SolidWorks/cworks/c_bolt_connectors.htm?id=9051573db1f342c89faf59fd9af4a068#Pg0
And in particular this page:
http://help.solidworks.com/2012/french/SolidWorks/cworks/Connector_-_Bolt.htm
Hello
I won't necessarily be able to help you with the tool itself but the phenomenon you describe doesn't necessarily seem incoherent.
How much effort do you put into your assembly? Do you have the same force on all the bolts?
My efforet is 2036 N. no the efforts are not the same on each bolt.
I have read the aids, but I would like to understand via a numerical example the different efforts found, as well as the coef. of secuirity than simulation calculation.
Thank you
Attached is my study.
I don't have SW available but, unless you have a large lever, this result is indeed surprising.
When tightening torque is applied, the bolts are subjected to this preload as long as the tensile force is lower (which is a priori the case).
By removing the tightening torque, the force should be distributed between the bolts following the lever arm.
See this tutorial http://www.lynkoa.com/tutos/3d/solidworks-simulation-la-gestion-des-contacts
Hello
The use of bolts is correct in your model.
On the other hand, in terms of contact management, you have to put a coefficient of friction (otherwise the parts have no reason not to move under load). Maybe that's why you put a stop ;-)
The management of contacts in general is daring but works well in this case (until now I always defined my contacts to limit the calculations, but I may review my models)
In my experience, the results found with the friction under simulation are good compared to theoretical calculations (on slopes for example).
In terms of your calculation, you should also have modeled a larger part of the H and not fixed the whole part: in practice your H is considered infinitely rigid, which it is not (especially given the thickness ratio) and as your analysis manages the contact you would get very different results (try for example to model the complete section of the H and fix only the opposite face at your fixation: the total displacements should almost double and your local constraints should also change to a lesser extent)
The torque corresponds to the initial tightening of your bolt (you can also put an effort). Depending on the calculation, the bolt will be unloaded or loaded, hence a variation in the possible value from one bolt to another. The whole theory is explained in the help as said by .PL
In practice your bolts are not (or very little) influenced by the load so it's normal that they all end up with almost the same value of effort / stress.
If you remove the prestress, the forces are due to the tensions/compression on the bolt related to the displacement of the parts (the bolt has an initial length, if this length blocks displacements you stretch it so you create a stress in the bolt) = you must therefore have very different values between the top and the bottom (I didn't do the calculation): a priori high tension at the top and because the part around the beam tends to open at the top and certainly not much at the bottom (because there are few deformations at the bottom).
Nb: I'm not sure but I believe that simulation creates a negative stress if you have compression (negative force) because it considers all the surfaces glued to the bolt while in reality in real life you will have zero effort with play between the bolt and your part: Thank you for confirming this for those who have had this case
Thank you all for these explanations.
I'm going to take a closer look at that now.
Thank you again.
Philippe