# Socem

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1. ## Element Coordinate System

Can I align all element coordinate systems for shell elements? Element forces are output in the element coordinate system and I am seeing discontinuities across componenet boundries because the element coordinate X and Y is switching. The projection rule in Hyperview does not seem to work on 2D element forces.
2. ## Offset All Elements by Half Thickness

Does anyone know how or does anyone have a script that will offset all shell elements by half the thickness on the property card. I am creating a shell mesh on the OML tool surface for a composite layup with PCOMP cards. Thanks

Create a cylindrical coordinate system at the center of the bearing and with the R axis pointed in the direction of the load. Then create an force equation: F = Load * cos(T) Basically, load decreases with angle away from the R axis. There are numerous studies for what this equation should be with higher order terms but cosine is a reasonable approximation.
4. ## Decoupling DOFs

Not sure if there is an equivalent in LSDYNA but CELAS, linear spring, elements can be used between equivalent nodes. Each spring has one DOF, so just use what you need to transmit load. However, I prefer the pin flags approach.
5. ## SOLID MESHING - CREATE 2D AND 3D ELEMENTS FROM SOLID

You need to slice your solid where you want the 3d mesh to end. Then just mesh what you want. Be careful though. I have found it best to just use a smaller mesh size to accomodate this members in a large solid. Solid elements only have the 3 translational degrees of freedom at their nodes. So if you but up a shell mesh to a solid mesh you will not transmit any bending. The shell mesh needs to be embedded at least two elements into the solid mesh. On a related topic if you want to create shell elements on the face of a solid mesh then use Tools -> Faces -> Find Faces. This will create shell elements on the exposed faces of the selected elements. This is useful for modeling composite honeycomb structure.
6. ## Creating a System with one of the axis normal to surface.

You can get a normal vector by: Create nodes along a curve. Offset the curve. Create the same number of nodes along the new curve. Create a normal vector from two nodes But, not sure how to get the tangent node you need to create a system.
7. ## Node Visibility

Unlike PATRAN, Hypermesh does not show nodes associated with elements, but they are there, otherwise the elements would not exist. If you click on the Card Edit icon, which looks like three folders one behind the other, and then click on an element you will see the NASTRAN card image which shows which nodes are associated with that particular element. It sounds like you are generating a temp node at each real node location. Be careful when applying loads so that you do not apply the load to the temp node when you mean to apply it to the real element node. Even if you do not "see" the node if the element is visible, the nodes are there. Just click the corner of an element when choosing a node to apply a load to.
8. ## Interfaces-contact surfaces

From the Analysis Panel try Interfaces and set type to TIE. Then click add from the same subpanel and change entity to csurfs. Create csurfs throug the edit button. This will glue two sets of elements together as contact surfaces
9. ## MATS1 Bulk Data Card

Does anyone know were I can set up a MATS1 card in Hypermesh?
10. ## Units in HM

Hypermesh in non-dimensional. It is up to the user to use the right units at each instance. For example, if CONM2 elements are assigned a weight then a PARAM WT-MASS conversion card needs to be present if running a normal modes analysis which relies on mass.
11. ## 1D versus 3D elements

CBARS are based on Eurler-Bernouli beam theory and CBEAMS are based on Timoshenko beam theory and include shear deformations. The number of elements does matter, but the actual math is simply based on the area and inertia properties of the 1-D element wtih stress recovery points being at the extreme dimensions, just as with an undergrad textbook.
12. ## Non Linear analysis

You need to determine what makes this problem non-linear. It could be large displacements, materials that are stretched outside their elastic range, or a non-linear application of loads. Think of non-linear analysis as involving something that is not instantaneous. Look into the parameter card NLPARM and the material card MATS1 which references both a MAT1 material and a TABLES1 card which holds points on a non-linear stress-strain curve. The loadcase will need to reference the NLPARM card.
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