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[Pasquale alessio Lentini]

Hello everybody, I am doing a project for my thesis.

I need to simulate three plates being hold together by 6 bolts.

The bolts are cylindrical and threaded on the top and on the bottom part, they are secured by a 600Nm torque and by calculations (given the M24, so the diameter) the preload should be around 125kN.

Now this being said, as contacs I put as bonded the bottom part because it is blind and goes into a thread of the lower plate, and bounded with the nut on the top thread.

Regarding the rest of contact, so between nut and washer and washer and plate as weel as between plates i used frictional contacts with coefficient 0,2.

If I mesh and run the simulation I get values over the strenght of the steel which seems not reasonable with high peaks in random spots regarding on the type of mesh I use.

So I was thinking i may be applying the pretension in the wrong way, or am I wrong anywhere else?

Any type of help is welcome.

Attached are screenshots.

 

Thank you in advance,

Alessio

[Aniket]

The first thing to check is if you are using nonlinear material properties. If you are not, then the results will go on increasing.

Please check the following course Metal Plasticity | Ansys Innovation Courses 

-Aniket

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[Pasquale alessio Lentini]

Thank you for your answer.

I just applied the materials usying isotropic elasticity and inserting in the Data Engineering the Young´s Modulus and the Poission Ratio.

Is this correct?

 

Alessio

[Aniket]

That will be linear material data, which would not be accurate, as the bolt seems to be deforming in the plastic region. Please review the course I suggested earlier.

-Aniket

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[Pasquale alessio Lentini]

I read it but the problem is that, almost 100%, we are not in the plastic deformation area, these are just bolts that are meant to keep the plates together, so the stresses should be way smaller, these are values from catalogues (regarding material and regarding pretension, coming from torque on the nut), so I don´t think we are working in the plastic region, that is why I was asking if my pretensioning was applied wrong and was the cause of these high, not expectable values.

 

Thank

Regards

Alessio

[José Pérez]

Check that the 'bonded' contact face is not within the preload application faces

[Pasquale alessio Lentini]

I did, I changed the application point of pretension, but it does not get better.

Regarding the contacts, is it okay if i leave it frictional or also bonded would make sense since i am interested just in the stresses in y direction. 

I cannot find the problem, it is a basic static simulation, can anyone help?

 

[José Pérez]

You could share the model proyect??

[Pasquale alessio Lentini]