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Input of Tapered Thickness for Plate Properties

Valued Contributor
Valued Contributor

Hi folks,

I have an I-Beam, whose flange thickness tapers from one end to the other. We prefer to maintain 2D FE representation of the structure and for flange thickness, in Patran, we could create spatial fields (tabular input or equation of dependent vs independent variable) and use this fields as input or thickness in Plate/Shell property.

 

I think in Femap, a dimensionless function can do the field representation but I could not find a way to input that function in to thickness of Plate property.

 

I am sure there is a way to accomplish the above, but I just couldn't find a way. Would appreciate some help.

 

Edit: Attaching solid model images...Part2a.JPGPart2.JPG

Thx...

9 REPLIES

Re: Input of Tapered Thickness for Plate Properties

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Hello!,

Tapered OFFSET with Shell elements done automatically since new release of FEMAP V11.2 (March 2015) using command “Modify > Update Elements > Adjust Plate Thickness/Offset”, give it a try to understand how to use it.

 

FEMAP attempts to update the element thickness and apply appropriate offsets for elements to better match the original solid used to create the midsurface(s). The Update to Solid section allows you to select how the solids used to determine thickness and offsets will be selected. When set to Automatic, each misdurface or element will automatically determine which solid to use, while when set to Solid ID, you will need to specify the ID of a solid or select s solid from the graphics window.

 

variable-thickness-menu.png

 

variable-thickness-animated.gif

 

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: Input of Tapered Thickness for Plate Properties

Valued Contributor
Valued Contributor

Such a simple solution! Have to try it out.

 

Thanks Blas man. Appreciate your reply. 

Re: Input of Tapered Thickness for Plate Properties

Valued Contributor
Valued Contributor

Blas, I tried the option you have mentioned and it did not work for me. I think the issue is with how the CAD solid model was provided. The assembly was converted to a Part (one single model) and then an IGS copy of the part was issued. So Femap is not able to recognize which surface/elements relate to Solid Model.

 

So, I am stuck...unable to input tapered thickness in Femap. If Femap folks are reading this, is there an alternate way to specify tapered thickness for elemental property card in Femap?

Re: Input of Tapered Thickness for Plate Properties

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Hello!,

You can use command MODIFY > UPDATE ELEMENTS > ADJUST PLATE THICKNESS/OFFSET to adjust the thickness or the offsets of the selected plate elements. You can update element thickness, element offset or element property. New properties are not required when using the Element Thickness or Element Offset options.

 

In the following example I have updated the element thickness using variable values based upon nodal position (Vary Between Nodes option). For the Vary Between Nodes option, you must input the first node, last node, and values at each of these nodes. FEMAP will then compute values for all other nodes attached to the selected elements based upon their relative distance between the From and To nodes. This option provides an easy way to gradually vary the thickness/offsets of plates which are in a patterned series.

 

tapered-thickness.png

 

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: Input of Tapered Thickness for Plate Properties

Valued Contributor
Valued Contributor

Hi Blas,

Interesting option. Thanks for pointing it out to me.


Quick follow up question. What is the difference between elemental thickness & property thickness?


Femap manual states that "If you have selected the Property Thickness option, new plate properties will be written for each thickness value calculated. New properties are not required when using the Element Thickness or Element Offset options. Currently defined offsets and thicknesses have no bearing on this command."


So if I already have a Plate property setup with dummy thickness of lets say 1mm and I want to apply variable thickness between nodes as you have illustrated, should I select Property Thickness or Elemental Thickness?


And one last question. Regarding your illustration, I see that you have selected Node 6 for 10mm thickness region & Node 1 for 5 mm region. Should I repeat the procedure for all nodes across the width of the plate or will Femap recognize that automatically?


Please see the attached pic for clarity on the above question.

 

large.png

Re: Input of Tapered Thickness for Plate Properties

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Hello!,

Play with the command with an small model, you will realize is very easy, don't worry to make mistakes, is the best way to learn, I do it every day!!.

If you select Property Thickness then FEMAP will create a lot of different properties, for tapered Shell elements better select Element Thickness.

Regarding the second question not need to repeat the command, FEMAP will compute values for all other nodes attached to the selected elements based upon their relative distance between the From and To nodes. This option provides an easy way to gradually vary the thickness/offsets of plates which are in a patterned series.

Best regards;
Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: Input of Tapered Thickness for Plate Properties

Experimenter
Experimenter

Hello!

 

I have currently FEMAP 11.1.2, I know that the new function is not ready in that version, but, is there a way to use the variable thickness/offset to have the elements only vary in one direction? in your previous example the elements taper off in both directions, for my particular application I need the elements to taper only in one direction, while the bottom part remains flat, can this be done with the command you previously showed or any other command for that matter?.

 

 

Thank you.

 

Oscar Escobar

Re: Input of Tapered Thickness for Plate Properties

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Dear Oscar,

In this case you need to repeated the command MODIFY > UPDATE ELEMENTS > ADJUST PLANE THICKNESS/ OFFSET two times:

  • In the first run you update the element thickness.
  • In the second run you update the element offset (this is the variable OFFSET resource of FEMAP).

The new command MODIFY > UPDATE ELEMENTS > MIDSURFACE THICKNESS and OFFSET do the job in ONE step, automatically. The following picture shows the comparison between the "two-steps" method and the automatic one, at the end the result is more or less the same:

 

ELEMENT-OFFSET.png

 

Best regards,
Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: Input of Tapered Thickness for Plate Properties

Experimenter
Experimenter

Dear Blas,

 

Thank you very much for your prompt response, I have tried doing what you suggested, however the elements change on both sides symetrically and wont allow me to have a flat side. I have attached a snip of the part I am trying to replicate as well as a snip of what the function adjust plate thickness/offset has done for me.

Thanks for any guidance.

 

Oscar Escobar