# Error with shell elements: a minimal example **URL:** \ **Category:** Uncategorized\ **Created:** [April 27, 2025, 1:58pm UTC](https://calculix.discourse.group/t/error-with-shell-elements-a-minimal-example/2721 "2025-04-27T13:58:51Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![hconel](https://avatars.discourse-cdn.com/v4/letter/h/bc79bd/32.png) [@hconel](https://calculix.discourse.group/u/hconel)\ **Post date:** [April 27, 2025, 1:58pm UTC](https://calculix.discourse.group/t/error-with-shell-elements-a-minimal-example/2721/1 "2025-04-27T13:58:51Z")
Hi, I am a CFD & finite volume guy, and a new CalculiX user (and new to FEM in general). My problem will probably sound very silly, but I couldn’t manage to solve it, so I’d appreciate any help. I am trying to understand the structure of a CalculiX case on this simplest possible case: ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/a/acc880cb797cf383f91dfc4cdad7d7aadccc9c33.png) Here is my job.inp file ```auto *INCLUDE, INPUT=mesh.inp *MATERIAL, NAME=steel *ELASTIC 210e9, 0.3 *DENSITY 7850 *SHELL SECTION, ELSET=plate, MATERIAL=steel, OFFSET=0 0.01 *STEP *STATIC ** Fix the root (all displacements = 0) *BOUNDARY fix, 1, 3 *DLOAD plate,GRAV,9.81,0.,-1.,0 *END STEP ``` and my mesh.inp file: ```auto *Heading test *NODE 1, 0, 0, 0 3, 1, 0, 0 4, 0, 0, 0.5 6, 1, 0, 0.5 7, 0, 0, 1 9, 1, 0, 1 2, 0.5, 0, 0 8, 0.5, 0, 1 5, 0.5, 0, 0.5 *******E L E M E N T S************* *ELEMENT, type=T3D2, ELSET=Line2 5, 3, 6 6, 6, 9 7, 4, 1 8, 7, 4 *ELEMENT, type=T3D2, ELSET=Line3 9, 1, 2 10, 2, 3 *ELEMENT, type=T3D2, ELSET=Line4 11, 9, 8 12, 8, 7 *ELEMENT, type=S4, ELSET=plate 1, 1, 2, 5, 4 2, 2, 3, 6, 5 3, 4, 5, 8, 7 4, 5, 6, 9, 8 *ELSET,ELSET=Unspecified 5, 6, 7, 8, *ELSET,ELSET=fix 9, 10, *ELSET,ELSET=load 11, 12, *ELSET,ELSET=plate 1, 2, 3, 4, *NSET,NSET=Unspecified 1, 3, 4, 6, 7, 9, *NSET,NSET=fix 1, 2, 3, *NSET,NSET=load 7, 8, 9, *NSET,NSET=plate 1, 2, 3, 4, 5, 6, 7, 8, 9, ``` And this is the output I get: ```auto You are using an executable made on So 31. Jul 13:26:31 CEST 2016 The numbers below are estimated upper bounds number of: nodes: 697 elements: 12 one-dimensional elements: 8 two-dimensional elements: 4 integration points per element: 8 degrees of freedom per node: 3 layers per element: 2 distributed facial loads: 0 distributed volumetric loads: 1 concentrated loads: 0 single point constraints: 945 multiple point constraints: 1441 terms in all multiple point constraints: 9217 tie constraints: 0 dependent nodes tied by cyclic constraints: 0 dependent nodes in pre-tension constraints: 0 sets: 12 terms in all sets: 54 materials: 1 constants per material and temperature: 2 temperature points per material: 1 plastic data points per material: 0 orientations: 0 amplitudes: 2 data points in all amplitudes: 2 print requests: 0 transformations: 0 property cards: 0 *ERROR in gen3delem: first thickness in node 1 of element 5 is zero ``` I checked the tutorials (and ChatGPT also), but still can’t pinpoint the problem. CCX complains about zero thickness, despite I define it. My mesh generation process: Create mesh in Pointwise (2D, solver: Gmsh) \> Export to Gmsh v2 format (.msh) \> Open in Gmsh \> Export to .inp format \> Make final modifications in the file. Thanks in advance. ---
**Author:** ![fgr](https://avatars.discourse-cdn.com/v4/letter/f/f4b2a3/32.png) [@fgr](https://calculix.discourse.group/u/fgr)\ **Post date:** [April 27, 2025, 5:52pm UTC](https://calculix.discourse.group/t/error-with-shell-elements-a-minimal-example/2721/2 "2025-04-27T17:52:14Z")
@hconel , you’re missing cross-section specification for elements line2,line3 and line4 if you add the following lines in your data-set you will get a result ```auto *SOLID SECTION,ELSET=Line2,MATERIAL=steel .025 *SOLID SECTION,ELSET=Line3,MATERIAL=steel .025 *SOLID SECTION,ELSET=Line4,MATERIAL=steel .025 ``` ---
**Author:** ![hconel](https://avatars.discourse-cdn.com/v4/letter/h/bc79bd/32.png) [@hconel](https://calculix.discourse.group/u/hconel)\ **Post date:** [April 27, 2025, 6:15pm UTC](https://calculix.discourse.group/t/error-with-shell-elements-a-minimal-example/2721/3 "2025-04-27T18:15:59Z")
Dear @fgr, Thanks for your answer. I noticed that although I do not want those line elements to be included in my .msh and .inp files, PointWise and Gmsh prints them anyway. I also noticed that deleting those type=T3D2 elements from the .inp file does not affect my simulation, and moreover, clears the error, leading to a successful simulation. Now I wonder, instead of deleting those manually, is there anything I can do in the CalculiX .inp file to set such elements “not to be simulated”, or void, ignore, something like that? ---
**Author:** ![JuanP74](https://avatars.discourse-cdn.com/v4/letter/j/b5a626/32.png) [@JuanP74](https://calculix.discourse.group/u/JuanP74)\ **Post date:** [April 27, 2025, 8:36pm UTC](https://calculix.discourse.group/t/error-with-shell-elements-a-minimal-example/2721/4 "2025-04-27T20:36:01Z")
export mesh from gmsh using Physical Groups, have a look at in gmsh website/manual > **[Gmsh 4.13.1](https://gmsh.info/doc/texinfo/gmsh.html#t1)** > > Gmsh 4.13.1 However we recommend to start as a new user with the graphical pre/post Prepomax (windows only): [https://prepomax.fs.um.si/downloads/](https://prepomax.fs.um.si/downloads/) ---
**Author:** ![hconel](https://avatars.discourse-cdn.com/v4/letter/h/bc79bd/32.png) [@hconel](https://calculix.discourse.group/u/hconel)\ **Post date:** [April 27, 2025, 8:52pm UTC](https://calculix.discourse.group/t/error-with-shell-elements-a-minimal-example/2721/5 "2025-04-27T20:52:33Z")
Hi @JuanP74, I have to work on Linux, so unfortunately I can not use PrePoMax…