Force de reaction

Simulation Generality
1

Hi all

I calculate a mast 2m high with a head force of 17100 N.

My base has three holes at the back of the force and two at the front, for fixing it on the concrete.

The locks are made on the support washers (fixed geometric).

When I display the resultant forces on the fixed geometry it gives me results on x,y,z.

Can I take these forces as the efforts that I will use to determine the diameter of my bolts? because I find them very high!

Thank you for your help

Kind regards

I have standard simulation.

 

 

2

Hello

I don't see the values very well, but you can check your calculation manually,

What I deduce:

1. Your rotation edge is located at the level of the 2 screws at the front

1.Bis [Edit] You want to know the forces in the 3 screws on the back (at the front on the picture)

2. Your screws will work mostly in tension plus a slight shear

3. So you can make a ratio between the height of the mast x the force applied and the distance between the rotation edge and the location of your screws at the back (basically, the length of your plate)

You will get an order of magnitude to verify your calculation.

1 Like
3

To complete:

Tensile force in a screw = [(mast height x force) / plate length] / number of screws]

4

Isn't the diameter of the screws more important to take into account than that of the washers?

1 Like
5

Hello

It is possible that the local deformation of the plate creates internal effects on the recesses that are not realistic. Which seems to be the case because the reactions on the angles seem to be in the opposite direction.

To check, for example, it would be necessary to block the horizontal displacements only on the center fixing and keep the 4 angles in tension only. In this case, we should find a shear force equal to the horizontal force at the masthead.

For the calculation of the bolts, it can be assumed that the shear is evenly distributed among the 5 screws. On the other hand, in the calculation, this shear must be taken up by rubbing on each fastener (otherwise it slips and there is a maximum of 2 screws that will take everything back in shear)

3 Likes
6

Hello

Thank you all for your answers.

I did Mr. Fives' calculation:

Fvis = (1710 daN x 2000mm) / 320mm = 10687 daN

I divide this result by 3 bolts  : Fvis = 3562 daN by bolts in tension.

The results on the bearing surfaces are completely different (see attachments).

I don't think we can use them to determine the Ø of bolts. Mr. Chamade must be right, I'm going to give it a try by not blocking all directions.

Thank you

Calimero.

 

 

 

 

 


capture_vis.jpg
7

Thank you for your feedback!

 

See you soon.