victorpbr
Mechanical
- Oct 13, 2014
- 74
Hi,
I'm trying to evaluate the design of a cargo tanker using FEA, however I'm struggling to get a good model and boundary conditions to work on.
Traditionally, when doing this by hand calcs, one calculates hoop stress and longitudinal stress from pressure, and then, treating the vessel as a beam calculate other stresses due forces and moments from load cases as in Article 1 (ASME XII, figure 1-1.4) and then just combine them accordingly to find the critical points and evaluate the combined stresses at that point. However this can become quite tricky when dealing with non-circular geometry, or when dealing with other discontinuities, hence my interest in learning to do it using FEA.
As acceptance criteria I think about using the same as ASME VII-2 however using ASME-XII allowables, as recommended on other similar topics.
I'd like to hear from your experience some good practices regarding this modelling, below are some thoughts I have that I'd like your opinion on, also if you have any good material or articles on this please share.
1- Regarding the 3D model - I have a model including the frame upon which the suspension system is mounted on, should I use it or better just to work with the vessel itself?
2 - Regarding support - On the area where the vessel is supported by the frame, i think about restricting the displacement only in the vertical and and transversal direction, allowing movement only in the longitudinal direction. However when checking acceleration and deceleration forces, I would fix one end and apply the force to the other end. Is this a proper way to do this?
3- Regarding application of force - I'm using ANSYS to perform this study, since in some cases the force is to be applied at ground level, I will have to use remote force, and then as target surface the cross section at the same plane this force is being act on. Is there a better way to evaluate this?
Thank you for your attention.
Victor
I'm trying to evaluate the design of a cargo tanker using FEA, however I'm struggling to get a good model and boundary conditions to work on.
Traditionally, when doing this by hand calcs, one calculates hoop stress and longitudinal stress from pressure, and then, treating the vessel as a beam calculate other stresses due forces and moments from load cases as in Article 1 (ASME XII, figure 1-1.4) and then just combine them accordingly to find the critical points and evaluate the combined stresses at that point. However this can become quite tricky when dealing with non-circular geometry, or when dealing with other discontinuities, hence my interest in learning to do it using FEA.
As acceptance criteria I think about using the same as ASME VII-2 however using ASME-XII allowables, as recommended on other similar topics.
I'd like to hear from your experience some good practices regarding this modelling, below are some thoughts I have that I'd like your opinion on, also if you have any good material or articles on this please share.
1- Regarding the 3D model - I have a model including the frame upon which the suspension system is mounted on, should I use it or better just to work with the vessel itself?
2 - Regarding support - On the area where the vessel is supported by the frame, i think about restricting the displacement only in the vertical and and transversal direction, allowing movement only in the longitudinal direction. However when checking acceleration and deceleration forces, I would fix one end and apply the force to the other end. Is this a proper way to do this?
3- Regarding application of force - I'm using ANSYS to perform this study, since in some cases the force is to be applied at ground level, I will have to use remote force, and then as target surface the cross section at the same plane this force is being act on. Is there a better way to evaluate this?
Thank you for your attention.
Victor