# Clamped shell + Rigid Body **URL:** \ **Category:** Uncategorized\ **Created:** [May 7, 2023, 10:30am UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641 "2023-05-07T10:30:35Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 7, 2023, 10:30am UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/1 "2023-05-07T10:30:36Z")
Hi ¿What would be the correct way to define this BC.? ![imagen](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/5/5139a1c249402fd0926a491e587e190cb0008677.png) It is related to this interesting post by Lucas Bueno. > [@Buckling of composite panels](https://calculix.discourse.group/t/buckling-of-composite-panels/1624/34): > > I’ve done a simple comparison regarding CalculiX buckling capabilities simply regarding differences in element types, solvers settings, and even your layered example. The geometry is a cylinder subjected to torsion and the results are compared to test data (NACA TN Number 1344) and theoretical values from Roark’s book, which can be seen in the next images. I use the following input data: [image] For the element type analysis, I run the default settings for 5 eigenvalues an… I can manage to improve the Buckling factor result up to 471.6 but there is no way I can completely remove certain out of plane rotation of the upper shell lip. (See Pict). That is most probably the last detail needed to achieve the exact analytical solution. ![imagen](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/2/2191e33e543161bb1621ad0473abe93d04acd610.png) ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [May 7, 2023, 11:06am UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/2 "2023-05-07T11:06:50Z")
How is the rigid body constraint applied here ? To the nodes of the top edge only ? Maybe a layer (or two) of rigid elements would be better. ---
**Author:** ![lucas\_bueno](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/lucas_bueno/32/1595_2.png) [@lucas\_bueno](https://calculix.discourse.group/u/lucas_bueno)\ **Post date:** [May 7, 2023, 5:16pm UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/3 "2023-05-07T17:16:27Z")
Very interesting improvement of the results, @Disla. How did you apply the BC? ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 7, 2023, 8:34pm UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/4 "2023-05-07T20:34:45Z")
Hi Lucas, I was already constraining some additional nodes apart from strictly the ones on the lip but seems it gets better adding a second thin row of elements. (Good point from FEA). A third one seems to much. ![screenshot.494](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/8/88c1d044f2f910fbe8c1a24b4473ac78159f88ae.jpeg) ```auto *SURFACE,NAME=NSet_Tip,TYPE=NODE NSet_Tip *COUPLING,REF NODE=2233,SURFACE=NSet_Tip,CONSTRAINT NAME=TipCouple *KINEMATIC 1,3 *STEP *BUCKLE,SOLVER=Pardiso 3,1e-5 *CLOAD 2233,6,100 *NODE FILE,GLOBAL=YES U *END STEP ``` My goal is to focus on S8R, KINEMATIC coupling and keep augmenting the complexity of the geometry to see where the laminates are failing if they are. I still think the issue was on the material definition (Maybe orientation) and local buckling modes. This is the best starting point I can get. Buckling Load : 473.5 (0.32% error) ![screenshot.493](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/1/114b0ddcd31b55d82369afd8e8cde47d03de80d0.jpeg) ---
**Author:** ![vicmw](https://avatars.discourse-cdn.com/v4/letter/v/6de8d8/32.png) [@vicmw](https://calculix.discourse.group/u/vicmw)\ **Post date:** [May 8, 2023, 11:20pm UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/5 "2023-05-08T23:20:22Z")
Do you have to use rigid body? Ordinary \*BOUNDARY constraints don’t work? ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 9, 2023, 6:26am UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/6 "2023-05-09T06:26:27Z")
HI Victor , How could I do that with \*Boundary?. I need to apply some loads and one Moment to the lip of an structure for further buckling analysis. I don’t see other option to distribute those loads. I’m finally using Fixed face on one side and Kinematic Coupling at the loaded side. Kinematic side shows some disturbaces. ---
**Author:** ![JuanP74](https://avatars.discourse-cdn.com/v4/letter/j/b5a626/32.png) [@JuanP74](https://calculix.discourse.group/u/JuanP74)\ **Post date:** [May 9, 2023, 2:24pm UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/7 "2023-05-09T14:24:41Z")
> [@Buckling of composite panels](https://calculix.discourse.group/t/buckling-of-composite-panels/1624/34): > > NACA TN Number 1344 ![Captura de pantalla 2023-05-09 a las 16.21.54](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/1/1e3db1128291b02c33caf580e303b6a430bd9994.png) ![Captura de pantalla 2023-05-09 a las 16.22.05](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/0/09bd36b67dcc7ea5d1db25e0ba03aebd49b0cf66.png) ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 9, 2023, 2:36pm UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/8 "2023-05-09T14:36:18Z")
Hi Juan, Victor, I’m familiar with those BC’s but how do I later apply the Moment?. I need a rigid body, kinematic or Distributed coupling which conflicts. I could set up the torsion by means of a rotation imposed in the circumferential direction but imposed displacements doesn’t work for buckling. ---
**Author:** ![JuanP74](https://avatars.discourse-cdn.com/v4/letter/j/b5a626/32.png) [@JuanP74](https://calculix.discourse.group/u/JuanP74)\ **Post date:** [May 9, 2023, 3:37pm UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/9 "2023-05-09T15:37:13Z")
you have to apply a traction in the loaded edge (_y_ coordinate in NACA’s nomenclature) whose only resultant is a pure torsional moment. In the case of linear elements it’s a uniform distribution of tangential point loads at the nodes of a regular mesh (all elements would have same edge length). Unfortunately CCX doesn’t have this capability already implemented in \*DLOAD so \*CLOAD cards have to be generated. ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [May 9, 2023, 3:52pm UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/10 "2023-05-09T15:52:11Z")
Methods to apply torque to a solid body (from Gokhale’s book): ![IMG_0857](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/e/e471e8cce17cf49dada960fe42cb5d536d5841b8.jpeg) ![IMG_0858](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/4/4d93a50aa59820c1515bbf5a88c3285f6a40115a.jpeg) ---
**Author:** ![xyont](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/xyont/32/3553_2.png) [@xyont](https://calculix.discourse.group/u/xyont)\ **Post date:** [May 9, 2023, 4:23pm UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/11 "2023-05-09T16:23:25Z")
> [@Disla](#): > > I’m familiar with those BC’s but how do I later apply the Moment?. I need a rigid body, kinematic or Distributed coupling which conflicts. I can not understand clearly. Can it be more specific details related to conflict? I was tested and frequently use coupling feature in CalculiX. Some code changes since versions 2.12 but only minor at input format and still available to the latest. Another [threads](https://prepomax.discourse.group/t/rbe3-integration-in-prepomax-kinematic-distributing-coupling/44) discussions at PrePoMax forums i replied. Example input file to download may still available there. ---
**Author:** ![JuanP74](https://avatars.discourse-cdn.com/v4/letter/j/b5a626/32.png) [@JuanP74](https://calculix.discourse.group/u/JuanP74)\ **Post date:** [May 9, 2023, 4:38pm UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/12 "2023-05-09T16:38:04Z")
right, these are the practical engineering methods, what I suggested is the numerical version of the mathematical condition so it can be better compared to the analytical analysis (Galerkin) used in NACA TN 1344 ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 9, 2023, 9:50pm UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/13 "2023-05-09T21:50:32Z")
> [@xyont](#): > > Can it be more specific details related to conflict? ¿Could I apply a \*Transform CARD to a REF Node ,the set of nodes belonging to the Slave surface or maybe both when defining a Rigid Body or Kinematic Coupling? I Mean: … … \*COUPLING,REF NODE=2233,SURFACE=NSet\_Tip,CONSTRAINT NAME=TipCouple \*KINEMATIC 1,3 … ¿Is there a way those 1 to 3 DOF refer to a coordinate system which is for example, Cylindrical? ---
**Author:** ![xyont](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/xyont/32/3553_2.png) [@xyont](https://calculix.discourse.group/u/xyont)\ **Post date:** [May 10, 2023, 6:04am UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/14 "2023-05-10T06:04:17Z")
> [@Disla](#): > > Could I apply a \*Transform CARD to a REF Node ,the set of nodes belonging to the Slave surface or maybe both when defining a Rigid Body or Kinematic Coupling? The loading is aligned to global axes, no local axes definition of reference node is required. Only in case of sloped member and load by \*Orientation function. \*Transform function is related to edge support since the model is cylinder shell with clamped, a restraint at local coordinate system is required. ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 10, 2023, 6:31am UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/15 "2023-05-10T06:31:07Z")
So, is that possible? \*Transform function at the edge + that edge being the slave surface of a Rigid or Kinematic Coupling at the same time.? ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 10, 2023, 7:56am UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/16 "2023-05-10T07:56:22Z")
This is an example of what I mean. Both shells (quadratic), are under a moment load at the upper lip and clamped on the base. If the moment is applied through the REF node of a Kinematic coupling, the nodes misaligned and generate peack Stresses. JuanP proposal to apply the moment as traction generates a uniform deformation pattern but I think would be way harder to set up (if not impossible) in a non-uniform surface like the wing. ![screenshot.518](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/7/7269d531f4cd41b68b3bc6b1ef10cd450f5288ac.jpeg) ![imagen](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/a/a3256cd1ac289fd032bec10ec804132637d50667.png) ---
**Author:** ![xyont](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/xyont/32/3553_2.png) [@xyont](https://calculix.discourse.group/u/xyont)\ **Post date:** [May 10, 2023, 8:39am UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/17 "2023-05-10T08:39:36Z")
> [@Disla](#): > > \*Transform function at the edge + that edge being the slave surface of a Rigid or Kinematic Coupling at the same time.? Documentation is not clear notified to avoid mixing, so probably it can be use or at least one keyword function is working. Previously i’m only curious about conflict you has been reported. > [@Disla](#): > > If the moment is applied through the REF node of a Kinematic coupling, the nodes misaligned and generate peack Stresses. It"s not a conflict reports, but unexpected behaviour and maybe the limitation itself. It seems the model still need a local rotational edge restraint, so knot can generates making rigid arm. In other way, did \*Coupling type \*Kinematic can be use as force/moment not displacement/rotation? ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 10, 2023, 9:02am UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/18 "2023-05-10T09:02:04Z")
This same moment and coupling works perfectly with linear shell elements. Thit is probably a bug if the moment is not translated into a force for middle through thickness nodes. This example is no more no less than the moment acting on the stiffeners on the wing. ![screenshot.524](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/1/18443288b08ab016b161866c90d786b036635609.jpeg) ![screenshot.523](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/4/4671d4dc4286706c42c7912d64a2163e4e14fe37.jpeg) ---
**Author:** ![xyont](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/xyont/32/3553_2.png) [@xyont](https://calculix.discourse.group/u/xyont)\ **Post date:** [May 10, 2023, 9:53am UTC](https://calculix.discourse.group/t/clamped-shell-rigid-body/1641/19 "2023-05-10T09:53:29Z")
> [@Disla](#): > > This same moment and coupling works perfectly with linear shell elements. > Thit is probably a bug if the moment is not translated into a force for middle through thickness nodes. Probably, cause of linear element does not have mid nodes then make it linearised and produce expectable results. It seems not a bug, need further check on slave definition. Actually, i’m also in learning of expanded element and knot or coupling in CalculiX