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2D elements without rotational DOF

Phenom
Phenom

Hello experts, short question:

 

Does NX NASTRAN (NX10) provide 2D-shell-elements without rotational DOFs, like  with 1D elements: rod elements and beam elements?

 

I want to use such elements in 3D models as a bending free stiffening of a solid surface (coat) or for directly for coating. The difference of having rotational DOFs or not is local bending if one tries to load such a meshed surface (3D solid + thin 2D coat) with pressure.

 

Or do I have to uncouple the rotational DOFs from element by special declaration in shell definition and rotational grid point singularities are then treated like grid point singularities of native solid mesh without connection to rotational DOFs of grid points?

 

Who can help, best wishes, Michael

| Production: NX10; Development: VB, TCL/TK, FORTRAN; Testing: NX11 | engelke engineering art GmbH, Germany
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5 REPLIES

Re: 2D elements without rotational DOF

Gears Phenom Gears Phenom
Gears Phenom

Mybe CSHEAR element.

Re: 2D elements without rotational DOF

Phenom
Phenom

look at the menbrane capability of a 2D element

Production: NX.CAE 9.0.3.4, NX.CAE 10.0.2.6
Development: VB.NET (amateur level !)

Re: 2D elements without rotational DOF

Siemens Phenom Siemens Phenom
Siemens Phenom

PSHELL has the ability to specify 4 material references: Membrane, Bending; Transverse Shear and Membrane-Bending coupling.

 

See PSHELL remarks (#2 in particular) for effects obtained by leaving various MID fields blank.

 

https://docs.plm.automation.siemens.com/tdoc/nxnastran/12/help#uid:index_QRG:id511716:id508696

Re: 2D elements without rotational DOF

Phenom
Phenom

JimB and all the others,

 

thank you for answering. I believe that I can fulfill my intention by suppressing

- MAT2 for Bending and

- MAT4 for Membran-Bending-Coupling.

Now I have to test it by using a solid mesh with and without a thin coat of a "adapted "membran mesh" Smiley Happy

I will see if it's work as I expect it and will post the results then.

 

Best wishes, Michael

 

 

| Production: NX10; Development: VB, TCL/TK, FORTRAN; Testing: NX11 | engelke engineering art GmbH, Germany
| Kudos for good posts! And if my post answers your question, please mark it as an "Accepted Solution".

Kick Off (2015-09-14)On the Map (2016-10-21)1st Gear 2018 (2018-02-19)To the Rescue (25, ‎2018-02-24)5th Birthday! (2018-02-25)Popular (100, ‎2018-10-30)Prolific (100, 2019-02-27)Philosopher (500, ‎2019-02-28)

Re: 2D elements without rotational DOF

Phenom
Phenom

Hi,

 

Short Edit: I have to deactivate MAT2, MAT3 and MAT4 entry in PSHELL property to get membrane state.

 

Then I made two simulations:

1. fully filled SOLID cylinder

2. same solid cylinder with MEMBRANE shell of thickness 1e-3mm on its outer surface.

 

Results are identically up to 5th decimal place.

 

MEMBRAN-SHELL_prt1_fem1_sim1.png

 

All rotational degrees of freedom of grid points were eliminiated (AUTOSPC=DEFAULT (ON)).

...
                                        M O D E L   S U M M A R Y

                                  NUMBER OF GRID     POINTS   =    17717
...
                                   NUMBER OF CHEXA    ELEMENTS =     4080
                                   NUMBER OF CQUAD8   ELEMENTS =      684
...
*** USER INFORMATION MESSAGE - SINGULARITIES FOUND USING EIGENVALUE METHOD *** 53151 SINGULARITIES FOUND 53151 SINGULARITIES ELIMINATED

 

I think the rotational DOF-contributions from shell elements to grid point DOFs are ZERO like, logically, from solid elements, too! Therefore, MEMBRANE shell elements behave analogous like solid elements or bar elements relating to rotational DOFs.

I believe, that's what I wanted to get.

 

Thank you. Best wishes, Michael

| Production: NX10; Development: VB, TCL/TK, FORTRAN; Testing: NX11 | engelke engineering art GmbH, Germany
| Kudos for good posts! And if my post answers your question, please mark it as an "Accepted Solution".

Kick Off (2015-09-14)On the Map (2016-10-21)1st Gear 2018 (2018-02-19)To the Rescue (25, ‎2018-02-24)5th Birthday! (2018-02-25)Popular (100, ‎2018-10-30)Prolific (100, 2019-02-27)Philosopher (500, ‎2019-02-28)