Learning Forum

[Chirag]

I am working on Type 3 hydrogen tank. Can anyone explain how I give liner thickness. Either I draw a liner of thickness and then go to Ansys ACP pre or I add fabric of liner in ACP pre and give as ply with 0 degree for liner. 

Currently I built a 2 geometry: one is of surface geometry without any thickness and link it with ACP Pre and the other geometry is of liner and link with mechanical model and then I add both in Static Structural because I need to perform Stress Analysis.

Can you please provide me the correct method for giving liner of pressure vessel.

[Zoi Stavrothanasi]

When the geometry is imported to the ACP, the thickness of the surfaces is overwritten when the layers are defined. After this procedure when the model is imported to Mechanical for a Static analysis shell elements have been transformed to layered shells (composite).

In the linked course you can access an example of how to model a composite pressure vessel. Hope this helps!

[Chirag]

https://link.springer.com/article/10.1007/s12206-021-0723-9 - Reference Paper

Respected Sir,

I am asking about the liner. I built layers but I am having problem with the liner part of the pressure vessel on which we apply the pressure. I am having difficulty in modelling liner. So my question how do I built liner part of the pressure vessel either I do liner thickness of liner as a layer or separate it out first built a geometry with thickness and link with mechanical model and then link it with structural part.

I am designing on the basis of this for validation. But how this paper goes don't hav any idea.Please help me!!!

 

[Chirag]

Can anyone reply for this problem?

[Zoi Stavrothanasi]

Both workflows mencioned are acceptable when modelling a liner. A good point to highlight is that when you are creating the liner in a different Mechanial model you need to apply the contacts between the liner and the composite part.  A suggested feauture to use is the Thickness from CAD Geometry in the modeling Ply dialog. This allows you to have a varying thickness through the liner.

A last comment, if you need to simulate effectively the filament winding process the third party tools are suggested. This way you will get an accurate representation of the liner in terms of thickness and fiber orientation.

Hope this helps you modeling!

[Chirag]

I want to do in Ansys ACP and what are the third party tools you referred in as a last comment?

 

[harshanagasai668]

Hello,
I am currently trying to model a copv with Isotensoid domes. I have successfully analyzed the cylindrical section but the dome portion is a bit challenging. I got the variable thickness with cut off section rule but the change in winding angle is not achieved even thought through look up tables. How did you do it?

[Chirag]

how you give it on dome with cutoff section rule? Go with lookup table as thickness is changing with radius in pressure vessel and draping is also governed with the correction angle on lookup table. Cutoff section rule is to difference out the hoop part and the helical part of the pressure. Please go with lookup table. Could you pleas explain me the procedure how you give the variable thickness with cutoff-section rule.

If your work is open to all or you are able to share your rough model (not the actual model) how you design cutoff-section rule for variable thickness could you please share any rough model with me. My mail is: guptacheerag@gmail.com

[harshanagasai668]

Ok. Will reach out to you. Thank You

[Chirag]

CIould you please share the steps how you do it?

[Reno Genest]

Hello Chirag,

As my colleague Zoi explained, you can model the liner as a layer in ACP or as an extra Mechanical Model system. Here is a video with the Mechanical Model approach:

https://www.youtube.com/watch?v=gL1bEdlAifM

One third party tool for filament winding is CADWIND. 

You will find an on-demand webinar on pressure vessel with Ansys and CADWIND here:

https://www.ansys.com/events/composites-webinar-series

 

If you don't use a third party tool, the way to model filament wound cylinders is by using lookup tables in ACP. The lookup table is used to specify the thickness and fiber angle for different X, Y, Z locations on the cylinder (pressure vessel). You will find more information in the following posts:

/forum/forums/topic/filament-winding-simulation-in-ansys-composites-prepost/

/forum/forums/topic/lookup-table-ansys-composite-prepostansys-acp/

 

Let me know how it goes.

 

Reno.

[Chirag]

Sir, I don't know how to design the lookup table for pressure vessel. How I give thickness and different winding angle in 3d lookup table. 

[harshanagasai668]

Hello, I tried it too. The change in angle has been is incorporated in it with reference to the edge rossete. More over, The thickness "CAN" be achieved with the help of cut-off section rule and a virtual geometry. I followed the ansys tutorial of Creating the lookup table. X,Y and Z coordinated and the fourth column is Dimensionless which is where the angle is mentioned. Selected tabular draping. The fiber draping is visible but it clearly not what i intented. I can identify the thickness variation as shown in the picture, but the change is angle( FIber draped angle) is being constant. 

But the actual model of the pressure vessel that i intent to create is like this as shown in below.

[Reno Genest]

Hello,

The information for lookup tables is here:

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v241/en/acp_ug/acp_Look-up_Tables.html?q=lookup%20table

/forum/forums/topic/lookup-table-ansys-composite-prepostansys-acp/

 

Please read the help carefully and follow the instructions.

 

 

Reno.