bolted joint simulation

[fabrypiro]

Good morning to all,

I would need your help to conduct a static structural analysis; below I expose you the problem with the help of some pictures.

The object of the simulation is a mechanical set bound by a support so that it can work as a bounce.

The only agent load is the weight of the structure.

the support is connected to the underlying element by means of pins and nuts and alone must support the entire structure, which therefore tends to inflect under its own weight; the objective of the analysis is to evaluate the right length of the support plate and, therefore, the number of necessary pins so that the load is distributed without letting the integrity of the structure (in particular what worries me is the tooth of the green part that I fear is "strapped" if the number of perno/dado pairs is too low).

Specifically I would need some advice on how to manually assign contacts between the superfacts so as to simulate the aforementioned connection, since the software often generates an error that prevents the resolution stage, or stress on the screws and teeth concerned is really very low (type 16 mpa), taking into account that the entire structure weighs about 20kg. Thank you!

 

[Stan9411]

frictional between the head of the screw and the grey support, bonded between screw and nut.
then the dice practically run into those rectangular section tracks? I would block them in that position with a bonded otherwise you will have a residual gdl. so much is a precautionary modeling.

 

[Stan9411]

Obviously the screws should be applied boot pretension. you should divide the analysis into two time stages.

 

[fabrypiro]

frictional between the head of the screw and the grey support, bonded between screw and nut.

then the dice practically run into those rectangular section tracks? I would block them in that position with a bonded otherwise you will have a residual gdl. so much is a precautionary modeling.

thank you for your availability first,

However, in reality, this degree of freedom would be blocked in reality by a further detail of the plate that I have not yet drawn, however, I must block this gdl... to block the nut in that position with a bonded contact which is the other surface to be considered?

 

[fabrypiro]

Obviously the screws should be applied boot pretension. you should divide the analysis into two time stages.

Normally how do you define the value of the bolt pretension ?

 

[Stan9411]

with a sheet of paper, a pen and some notion of mechanical design

 

[Stan9411]

If you miss a physical part of the object I don’t think it’s easier to create equivalent constraints. you should draw missing details so be sure to have a realistic modeling

 

[Fratellino]

Normally how do you define the value of the bolt pretension ?

from the tables of the closing pairs of the screws.
but it's a feature that I don't know if it exists in academics and requires a little change of cad, like creating a piece of life stem that doesn't have any other contacts if not two bonded at the ends, to which you will apply your bolt pretension.
the analysis must precede two loadsteps in general, one in which the bolts are closed, no in which the external load is applied to bolt closed.
between the plate and the profile must be inserted a frictional contact as between the head of the hammer screw and the plate.

 

[fabrypiro]

from the tables of the closing pairs of the screws.
but it's a feature that I don't know if it exists in academics and requires a little change of cad, like creating a piece of life stem that doesn't have any other contacts if not two bonded at the ends, to which you will apply your bolt pretension.
the analysis must precede two loadsteps in general, one in which the bolts are closed, no in which the external load is applied to bolt closed.
between the plate and the profile must be inserted a frictional contact as between the head of the hammer screw and the plate.

Thank you.

Could you be more kind to tell me what you mean to "close the bolts"?