Reaction force to a flat and curved surface study 2

[jmex]

Hello Engineers,

I have two different geometries, where i know the value of pressure. I would like to know the reaction force on both the scenarios. Applying the same pressure on both the geometries, there is not at all difference in reaction force in vertical direction (even though the surface area is different).

If this is not the way we could find the reaction force, kindly suggest one.
I thought the applying force in vertical direction on the component surface would make two different vectors (Horizontal and Vertical). But it didn't happen.
Thank you!

 

[rothers]

Correct, the vertical reactions are the same, the net horizontal reaction is zero in both cases.

 

[rb1957]

the surface area is different, but the projected area normal to the pressure is the same.

"Wir hoffen, dass dieses Mal alles gut gehen wird!"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[jmex]

thank you for your reply folks, that is what I am trying to understand. As such the pressure will be from the fluid beneath them and will be applying same pressure (as per pascal's law). If instead of the curved surface, if we take a ball of the same diameter, will the reaction force be the same in both the scenarios?

 

[rb1957]

pressure acts normal to the face (unlike your 2nd pic).

the force created by the pressure is any direction depends on the projected area normal to that direction.

I don't understand "If instead of the curved surface, if we take a ball of the same diameter," ... do you mean if we submerge a ball into a fluid (pressure field) ??

"Wir hoffen, dass dieses Mal alles gut gehen wird!"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[jmex]

@rb1957, the arrows in both the pics are of force direction. I forgot to mention the force. And yes, the pressure will act normal to the face.
The ball half under water, pressurized from below (so it will not be under hydrostatic pressure, which will result into different pressure values on the surface).

 

[rb1957]

ok, could've been simplistic sketching. So there'[s a medium between the applied force and the curved surface, so the pressure is normal to the surface, equivalent to the applied load.

Still not getting the ball thing ...
1) "The ball half under water" ... so buoyancy and weight balance the hydrostatic pressure on the ball ... pressure is normal to the local surface and in this case not uniform;
2) "pressurized from below" ... now when add load to the ball, how is it going to react it ? draw the FBD.

"Wir hoffen, dass dieses Mal alles gut gehen wird!"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[Stress_Eng]

I believe your question looks similar to the case where you assume the contact for a pin loaded lug is cosine in shape. It may give you some ideas?

 

[jmex]

hi, let's assume that these both are valves, these have pneumatic pressure applied onto the surface. I have pressure values inside the tank. As such the tank is big, and there is very less variation of pressure inside the tank, I am assuming constant pressure which is acting on the surface. As such the design is symmetry, lateral components of forces will nullify but will there be not difference in force in vertical direction for both scenarios?

Forget ball under pressure as it might create more confusion.

 

[rb1957]

if the projected area of the two is the same, then the pressure load is the same.

"Wir hoffen, dass dieses Mal alles gut gehen wird!"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.