Mechanical Boundary condition of a Floating Structure

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Discussion Overview

The discussion revolves around the mechanical boundary conditions of a floating structure that has undergone CFD simulation. Participants are exploring the unexpected deformations and displacements observed during mechanical analysis when applying fluid forces as external loads.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Shade describes the issue of unexpected large bending or no displacement in the floating structure when applying different boundary conditions such as fixed and pin.
  • One participant inquires about the nature of the deformations and suggests constraining the model to allow for expansion/contraction while preventing rigid body motion.
  • Shade indicates a preference to constrain the structure by its mooring position, expecting stress distribution but not frame displacement, and mentions experimenting with various constraints.
  • A later reply expresses uncertainty about providing further assistance without more detailed descriptions or images of the problem.

Areas of Agreement / Disagreement

The discussion remains unresolved, with participants exploring different approaches to boundary conditions and expressing confusion about the observed results.

Contextual Notes

There are limitations in the description of the problem, including the lack of visual aids and specific details about the unexpected deformations or displacements.

shade rahmawati
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Dear all,

I made a cad of floating structure (the frame only), figure attached below. It should be located in the water and moored, so it can't go anywhere. The CFD simulation was done. So I have fluid force on the structure. Now I want to do mechanical analysis of the structure by apply the fluid force as external load. I have no problem in operating the software. My problem is, I already try some scenarios of boundary condition of the structure, such as fixed, pin, etc., and I found that the deformation isn't as expected (large bending) or no displacement at all.
Any idea?

Regards,
Shade
 

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What is the nature of the unexpected deformations or displacements? Are you constraining the structure by its floats? As a general rule you will want to constrain the model such that expansion/contraction can occur but rigid body motion cannot.
 
Mech_Engineer said:
What is the nature of the unexpected deformations or displacements? Are you constraining the structure by its floats? As a general rule you will want to constrain the model such that expansion/contraction can occur but rigid body motion cannot.

Thank you. I want to constraint it by its mooring position. So probably there won't be any frame displacement, but I expect there's stress distribution.
So, I'm still try any combination of constraints at different part of the structure.
Confused? Me too

Cheers
Shade
 
Without a better description with pictures of the problem you're seeing, I'm not sure we can help you any more effectively.
 

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