I have a pump + motor screwed on a metal frame (I can't put an image for privacy reasons).
This chassis is itself screwed into the ground by 12 screws. My goal is to determine the forces at the level of these 12 screws. (stress torsors being applied to the pump)
I then tested several models but they all give different results (very different even):
- Fixing the cylindrical faces of the 12 screw holes WITH virtual wall with the floor
- Fixing the cylindrical faces of the 12 screw holes WITHOUT a virtual wall with the floor
- "Remote loading" where I block the 6ddl in the center of the 12 screw holes
- Connectors, anchor bolts + wall then I recover the force in the connector
- Diameter, torque, washer diameter all have an impact (quite strong even)
In your opinion, which model is the most suitable?
Hello
In my opinion, the cleanest way is to make anchor bolts between your chassis and the ground.
You apply remote loading on the pump fixing holes on your chassis (either rigid or flexible but this should not change much on the result at the 12 fixing points if you have a little distance between the pump and the points).
You should get a correct result (which assumes that the 12 bolts are all well fixed as they should be and in the same way which is impossible because ultra hyperstatic: in reality only a few feet will be in contact before tightening (unless all your feet are finally machined)).
Hello @froussel,
Yes, it seems to me the best method for me too.
The problem is that I don't know the characteristics of the screw (diameter and torque) and these 2 parameters play a lot on the axial force that I recover. Is it necessary to put a torque or a tension?
Yes, otherwise it takes off and it diverges...
You can at least put a slightly higher effort than the one in the same direction on your pump.
Otherwise there is a good chance that it will be 8.8 mini on site (difficult to find worse nowadays unless you look for it specifically).
Logically the diameter should be the one just below that of your hole.