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1. Mrt liked a post in a topic by Hyperman in using nonlinear subcase for linear buckling
That document is from Reference Guide>Input Data>Subcase Information Section>STATSUB.
STATSUB.pdf
2. Mrt liked a post in a topic by Hyperman in using nonlinear subcase for linear buckling
Glad to help.
NLSTAT+BUCKLING.fem
3. Mrt liked a post in a topic by Hyperman in using nonlinear subcase for linear buckling
Hi,

it is possible to use nonli﻿near quasistatic analysis as a preload for linear buckling analysis (see attached model). From Optistruct help:

NLASTAT+BUCKLING.hm
4.
The penalization technique used is the “power law representation of elasticity properties,” which can be expressed for any solid 3D or 2D element as follows:
K(r) = K*ρ^p
where K and K represent the penalized and the real stiffness matrix of an element, respectively, ρ is the density and p the penalization factor which is always greater than 1.
In OptiStruct, the DISCRETE parameter corresponds to (p - 1). DISCRETE can be defined on the DOPTPRM bulk data entry. P usually takes a value between 2.0 and 4.0. For example, compared to the non-penalized formulation (which is equivalent to p=1) at ρ=0.3, p=2 reduces the stiffness of the element from 0.3 to 0.09 times the stiffness of the fully dense element. The default DISCRETE is 1.0 for shell dominant structures, and 2.0 for solids dominant structures (the dominance is defined by the proportion of number of elements)
5. tinh liked a post in a topic by Mrt in Topology optimization results interpretation
The penalization technique used is the “power law representation of elasticity properties,” which can be expressed for any solid 3D or 2D element as follows:
K(r) = K*ρ^p
where K and K represent the penalized and the real stiffness matrix of an element, respectively, ρ is the density and p the penalization factor which is always greater than 1.
In OptiStruct, the DISCRETE parameter corresponds to (p - 1). DISCRETE can be defined on the DOPTPRM bulk data entry. P usually takes a value between 2.0 and 4.0. For example, compared to the non-penalized formulation (which is equivalent to p=1) at ρ=0.3, p=2 reduces the stiffness of the element from 0.3 to 0.09 times the stiffness of the fully dense element. The default DISCRETE is 1.0 for shell dominant structures, and 2.0 for solids dominant structures (the dominance is defined by the proportion of number of elements)
6. Mrt liked a post in a topic by Hyperman in Energy Error Limit Reached
Hi @PhilippFr

this error is common with inappropriate mass scaling, that is when you impose a time step which is too high. Check the mass error due to mass scaling in the engine .out file: in your model the mass scaling increases the system's mass by more than 100 times! It is suggested to keep the overall mass increase below 2% and even then it has to be checked if the mass is added to parts that are moving, which would increase the kinetic energy and therefore decrease the simulation accuracy. A short video on energy and timestep error
https://altair-2.wistia.com/medias/osd349gz4k

Energy error.pdf﻿

Alternatively, you could try with advanced mass scaling (AMS) which does not add mass.

You can find more information from Introduction to Explicit Analysis using RADIOSS – A Study Guide in Time Step Control chapter. Also recommended is 2017 Radioss user guide starting from page 30.

However, the model you presented is not suited for explicit simulation as the minimum natural timestep due to CFL condition is 1e-11, which is practically unsolvable with the current computational capabilities. Rethink your modeling approach (beam instead of solid) or solve the problem with implicit.
7.
To recover your data in a CAD-readable Format (STL), you can use the HyperView Tools – Export – Iso Surface Option.
Other ways to recover STEP oder Polynurbs Geometry (smoother results) are:
-        Use HyperMesh -> Pulldown Menu Optimization -> Ossmooth -> Geometry Format STEP to export a CAD File of the optimized result
-        Use Polynurbs in solidThinking EVOLVE or INSPIRE. See here for more details:
http://solidthinking.com/training/2016/inspire/content/polynurbs/polynurbs_tools.htm

Kind Regards
Jan
8.
hello, @Roy Duan!
what tool did you use?
have you ever used this feature for midmesh?
Direct Midmesh Quick Start Guide - v1.pdf
9. Mrt liked a post in a topic by nvn in Cabin Thermal Simulation
Hi,

i have to simulate the airdistrubiton on the windshield, so i modulated a cabin with a airflow. So i have 2 volume, how can i define the intersection(surface) between airflow-volume and cabin-volume ? I have set on the  Type: wall and  wall function : None , is that correct ?

10.
Hi Dakshitha

You can separate the fibers from liquid/rubber using Boolean operation and then retrieve only liquid/rubber material and mesh it separately.
Please follow below post for reference

Thank you
11.
I think it maybe a bug....plotted using "build Plots", it give correct plots.

Regards
Nachiket

12. Mrt liked a post in a topic by ydigit in HyperMesh 2D Mesh Import Error in AcuSolve
Please import the mesh_intersections.nas in HyperMesh. This will give you an idea of where the problem region is this. As the name tells, there are intersecting elements in this region.

13. Mrt liked a post in a topic by Farzin in Contact Penetration
Hi @Prakash Pagadala
Thanks a lot for your efforts.
Unfortunately, I have no acces to Abaqus Modell. I just received the Mesh and built the model all by myself in Hyperworks. I read a Research, that used the same Model in Abaqus. I used their boundry conditions for my Modell (same Material_same Forces ...). I have no clue about Abaqus convergence Algorithm.
I will update you, if i find something new.
14. Mrt liked a post in a topic by ppraf in Points in a different coordinates system
Hello -

You should be able to do this by using the "Parametric Points" tool.
In 2017.2,  it is available in the side toolbar as shown in the attached image

Regards
Praful

15.
I think people don't have time to help you from A to Z
So it's better if you do some initial codes, and ask for help in details eg: how to read file/ write file by tcl...
16. Mrt liked a post in a topic by Hyperman in ERROR ID : 257
Hi Antonio,

there are so many modeling errors I suggest you check the Radioss free ebook. Also please go through the attached tutorial on how to create a 3 point bend test.
For model debugging use Tools>Model Checker>RadiossBlock and review the .out files for errors and warnings.

I have modified the model so it can run:
-contact was not defined properly
-shell elements that come into contact had wrong normals orientation 2D>composites>element normals>reverse
-the plies were not referencing elements
-the laminates were missing
-delete the ^tempCompSurfSegment component
-delete the type 2 tied interface as equivalencing nodes (shift+F3) works better to connect face sheets to honeycomb
-delete the RBE3 component and use RBE2 to create rigid on stamp component
-create boundary condition on the independent node of RBE2 to block all DOF except Y translation
-edit the TH group, as it is referencing non-existing component ID 7
-the mass scaling is imposing one magnitude lower timestep (7e-7) than natural (6e-6). Instead, mass scaling should be used to impose a higher timestep.
-time scaling is recommended as 420 seconds is inefficient for explicit. Reduce the simulation duration until you get a quasi-static  solution (total kinetic energy to the total internal energy is small enough - normally less than 5%).

RD-T_ 3595 Three Point Bending with HyperMesh.pdf
3pb_radioss_modified_0001.rad
3pb_radioss_modified_0000.rad
3pb_radioss_modified.hm
17. antonio.dortona95 liked a post in a topic by Mrt in Failed mesh
your mesh is good, guy!
don't worry=)
just unchek "min size"

18. Hyperman liked a post in a topic by Mrt in 3d meshing support needed
at first-Do you use HyperMesh? or LSprepost?
your surface:

just mesh it!=) like this, Anna!

p.s. i don't know why, but in this area your mesh shoulbe like in my pic below... otherwise HM won't make solid mesh right.
if your solver will be dyna you should know about timestep.=)

19. Mrt liked a post in a topic by Pranav Hari in error id 760
Hi

The corrected file is shared here.

BENDING_0000.rad
BENDING_0001.rad
20. Mrt liked a post in a topic by Pranav Hari in error id 760
Hi yugang
You can click delete button from the tool bar,  select elements by config.
Then select the shell elements and click, delete

21.
Hi,
First, you draw the final profile ACD,
From menu Morph>Free hand:
1) Morph B to D

==>

2) Enter panel F7>remap
remap below misaligned nodes:

3) Enter panel smooth to adjust mesh lines

==> Is this OK for you?

22. Mrt liked a post in a topic by MattM in How to creat 2D element from nodes
I agree, I would calculate with shell elements.

However, I have tested this myself. I created a simple model of a cantilever beam and compared different solid meshes with the max output von Mises stress result.

Via hand calculations (baseline): Stress = 600 MPa
1x HEX8 element through thickness: Stress = 565 MPa
2x HEX8 element through thickness: Stress = 604 MPa
1x TET4 element through thickness: Stress = 154 MPa
2x TET4 element through thickness: Stress = 387 MPa
1x TET10 element through thickness: Stress = 623 MPa

The results are a bit iffy because the max stress is located near the constraints (I should've done this using a 3-point bending model...) You can clearly see here that TET4 elements are bad at calculating stresses through the thickness due to bending. However the TET10 element (with midside nodes) is a lot better.

Still, for best results calculating stresses through the thickness I would be using HEX elements (where possible) for thick components and QUAD elements for thin shell components.
23. magicbarald liked a post in a topic by Mrt in "Element Densities" definition
With the density method, the material density of each element is directly used as the design variable and varies continuously between 0 and 1; these represent the state of void and solid, respectively. Intermediate values of density represent fictitious material. The stiffness of the material is assumed to be linearly dependent on the density. This material formulation is consistent with our understanding of common materials. For example, steel, which is denser than aluminium, is stronger than aluminium. Following this logic, the representation of fictitious material at intermediate densities does reflect engineering intuitions.
In general, the optimal solution of problems involves large gray areas of intermediate densities in the structural domain. Such solutions are not meaningful when we are looking for the topology of a given material, and not meaningful when considering the use of different materials within the design space. Therefore, techniques need to be introduced to penalize intermediate densities and to force the final design to be represented by densities of 0 or 1 for each element. The penalization technique used is the “power law representation of elasticity properties,” which can be expressed for any solid 3D or 2D element as follows:
K(r) =K* ρ^p
where K and K represent the penalized and the real stiffness matrix of an element, respectively, ρ is the density and p the penalization factor which is always greater than 1.
In OptiStruct, the DISCRETE parameter corresponds to (p - 1). DISCRETE can be defined on the DOPTPRM bulk data entry. P usually takes a value between 2.0 and 4.0. For example, compared to the non-penalized formulation (which is equivalent to p=1) at ρ=0.3, p=2 reduces the stiffness of the element from 0.3 to 0.09 times the stiffness of the fully dense element. The default DISCRETE is 1.0 for shell dominant structures, and 2.0 for solids dominant structures (the dominance is defined by the proportion of number of elements). An additional parameter, DISCRT1D, can also be defined on the
50
24. Mrt liked a post in a topic by tinh in Checking penetrations between parts
Could you try running it in hypermesh (not hypermesh desktop)
25. Mrt liked a post in a topic by tinh in Checking penetrations between parts
OK. so i will make a script with a loop that project node to the closest elem
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