Problem balancing pressure vessel forces

[CSR24]

Hello everyone,

I'm a first-arm mechanical engineering student with ansys and I'm doing a project with the university.
I am trying to make a stress analysis with ansys workbench of a pressure vessel (press vessel) to be mounted on an offshore platform.

I did the model with dm, so I continued on static structural. As a first test I have inserted only the force of gravity, so the reaction forces on the supports (saddles) of the pressure vessel should be such as to then have reaction forces = 0.

I think I have correctly set the direction of gravity force to my model (direction -y) and expect that the y components of reaction forces on the saddles have towards opposite but same intensity and instead are greater than the weight of the vessel.
I tried to apply the weight of the container in one point (nodal force) and I got the balance I expected, but if I put gravity I can't. do you have any advice on how to try to fix this problem?

thanks in advance

 

[lucadileta]

Hello everyone,

I'm a first-arm mechanical engineering student with ansys and I'm doing a project with the university.
I am trying to make a stress analysis with ansys workbench of a pressure vessel (press vessel) to be mounted on an offshore platform.

I did the model with dm, so I continued on static structural. As a first test I have inserted only the force of gravity, so the reaction forces on the supports (saddles) of the pressure vessel should be such as to then have reaction forces = 0.

I think I have correctly set the direction of gravity force to my model (direction -y) and expect that the y components of reaction forces on the saddles have towards opposite but same intensity and instead are greater than the weight of the vessel.
I tried to apply the weight of the container in one point (nodal force) and I got the balance I expected, but if I put gravity I can't. do you have any advice on how to try to fix this problem?

thanks in advance

hi csr24, put some photos or the project file so I can help you

♪

 

[CSR24]

hi csr24, put some photos or the project file so I can help you

♪

Hello, luca.

As you can see in the first image, my pressure vessel has the two supports not exactly the same distance. the material of the supports is different than that of the vessel and I have both inserted them manually in data engineering.
the total weight of the body is about 36618 n, so if I insert only the force of gravity and the two supports, I expect that the sum of reaction forces in direction y applied to the base of the supports is equal and contrary to the weight.
in the following photo you can see that the force reaction applied to the fixed support is 18456 n.
instead on the following support I defined a displacement and the body is free in direction x and z while it is fixed in direction y.
In this case, force reaction 2 = 25725 n.

♪18456 + 25725 = 44181 n
a very different figure than the weight of the body (36618 n).

At this point I tried to insert a nodal force in a very approximate manner to the center of the vessel and in this way reaction forces are exactly equal and contrary to the weight of the body.

I also tried with alternate geometries and get the same thing...

 

[lucadileta]

Hello, luca.

as you can see in the first image... .

I also tried with alternate geometries and get the same thing...

Hello, csr24,

as in this period I am very messed up with the job, post me directly the project file zipped so I open it in the office, I look at it and give you a precise answer.

♪

 

[volaff]

Hey, guys, how did it end then?