I want a simple action.

one harder cylinder (Deformable solid) comes at a velocity and hits a very thin layered wall of soft tissue (Deformable solid) and deforms it

but there is always an error. mostly, the wall tries to stay rigid and rather than deforming, has its mesh distorted. as in, rather than the middle of shape bending backwards,it stays firm and the mesh of the contact surface get deformed and eventually pierce one another

I used explicit dynamic step

I used a contact type interaction property. interactions are: 1. general contact and 2.surface to surface contact

mesh are hex and they seem fine enough. standard linear for cylinder and explicit linear for wall

errors are often:

The ratio of deformation speed to wave speed exceeds 1.0000 in at least one element.

mesh element is distorted

Is there a way to append (i.e. add or remove nodes/elements into) an existing node set or an element set in Prepomax. Whenever I try to edit the set, either removes the previously saved nodes (inspite using shift) or throws an error. Thanks in advance.

I have a strong background in structural engineering but do not have applied FEA/FEM skills.

How can I learn the nuanced details of FEA/FEM without on the job training like: contact, plasticity, impact, creep load step, modeling connections, meshing, buckling, nonlinear statics, transient response, etc...

I am trying to run a simulation in Hypermesh; I am pretty familiar with the software and have been using it for quite some time; however, for a simulation I am doing, I need to constraint one axis in a direction that is tilted with respect to the global reference system.
The only option that makes sense to do this is to create a local coordinate system with the "System" command, and then assign it to the desired constraint, in the tab of the image. This works well with loads, but when I apply it to a constraint, there is no confirmation screen or way I can check if this has been succesfully done, and the simulations are not working as expected (the constrained direction is still in global coordinates. Is this a bug? Am I doing something wrong? Thank you in advance; this operation seems way more obvious in previous versions of the software

https://preview.redd.it/y6b7yxu84a4e1.png?width=1920&format=png&auto=webp&s=3248506841a4553cd30d14aabaf5d8bf3c1698d5

New beginners video on how to create a ply based model on https://www.youtube.com/@learncarbonfiber THANK TOU👍

It may sound silly, but I’m slightly confused. I have a component that needs to be tested in frequency response. The component will be tested on a shaker table.

Bcs The component is in contact with the shaker table through four brackets. Now while modelling this in Hypermesh optistruct , I create 4 RBE2 elements, all on the bottom surface of the bracket and excite it.

Question

1. Since I am applying load through four points, each of those load get summed up as it is applied on the component. That means if I apply the same load on each of RBE2 element that would multiply the load four times. is it okay to do that, or should I create just one RBE2 element that connects to the bottom face of the four brackets.

Which one of the two method is more accurate in describing the actual boundary condition?

So right now I have quite a lot of experience in mechanical FEA and CFD.

Since there are now several powerful tools available for free (OpenFOAM, FreeCAD, SALOME etc..) I was thinking to start freelancing as a side hustle, and maybe in the future making it become a full-time job.

Any of you guys did this and wants to share their experience or have any tips on how to start?

I was thinking one of those freelancing sites like fiver or something, I still didn't really look into it.

I only have access to static software, with no chance to purchase better software from the company.

Is there a way or trick to approx rubber materal in a static? Can i do something to linear properties? I wanted to use a mooney-rivlin model but once i started i only then realised the software says no. And i had prepares for a nonlinear analysis. Damn.

Hello everyone! I really need to perform topological optimization under the action of contact stresses in the teeth of two gears. But my teacher said that usually topological optimization is not performed on contact. Is this so and why?

I planing to buy a new laptop (not that expensive) for my personal use(to run toy peoblem) and to run some software

1. Matlab
2. Adams
3. Hyperworks suite

So, is this configuration enough of I need something else

[Ps it's a thinkpad]

Hi everyone, so I recently posted in regard to a fatigue analysis I was studying.

Since I didn't have the stress vs cycles data I was trying to run cycles to simulate it. Anyway, wrong method, not feasible, etc...

So, I recently got the complete experimental data for the material I'm analyzing (I did not have it at that moment) so I decided to doing it this way

I stayed with my 1C, 3C and 5C, two reversals per cycle, and got the max LE logarithmic strain as 0.001297 in all this analysis.

So I took this value and my understanding is that this is the (delta strain/2) value so there is no need to divide that strain between two.

So when I run the iterations (on the formula) to get the amount of cycles I get 9.05x10^7 cycles for that LE.

Now, my simulation max stress is 247 MPa, which is bellow the yield strength point 310 MPa, so it remains on the elastic zone.

I understand that (sigma'f/E)(2Ni)^b belongs to the elastic zone and (epsilon'f)(2Nf)^c belongs to the plastic zone.

For what I got on the simulation, I would understand that the LE I got it only belongs to the elastic strain (probably a plastic strain too but insignificant value, right?)

So, the dumb question here is, when I'm looking for the cycles through this method it should be taking in count the plastic segment of the formula even if there is no plastic strain?

Hello, good morning,

For a project, I have made an explicit simulation of a longitudinal crash member. Extracting the following force curve from the RigidWall-Crash member contact. The red one is the force as it comes out, and the black one is filtered with a Low Pass Filter at 180 Hz.

Now I want to design the joint at the base of the crash member, and I had thought about extracting this force to calculate, analytically, the number of screws needed and their tightening torque.

My question is, should I use the peak value of the contact or can I use the peak of the filtered signal?

Thanks

https://preview.redd.it/3m5c9xdsvf3e1.png?width=817&format=png&auto=webp&s=11b0b4b59d1106a6e3a21807efb9dae260fb3312

Hello, I want to build a simulation model with more components. I don’t want to use the glue function because it just makes problems. So I decided to use multiple parts, unite them to one solid and then mesh them all together so that the edges are clean. But know I want to give three different material properties to the different parts and have to select them properly. But Flood and Association didn’t work since I have just one meshed solid. Is there a way to maybe define user boxes with the shape of the particular solid bodies so that I can select every element inside the box and then give the material properties? Thank you very much in advance!

I am doing an FEA on a lifting lug. I am confused as to why Hex elements are showing an oscillatory behavior for the stresses (the non contact stress is at the fillet and the contact stress is at the hole)

A bit of an introduction

We have developed some unique FEA/MBD simulation capabilities and I hope that this community can give us some new use cases for our technology. Currently we use our software for both static and dynamic simulations of mainly drive train components such as bearings, gears and gearboxes. These are mostly applications that involve high contact loads and where component flexibility is important.

The (some not so) unique features

• We combine FEA with multi-body-dynamics (MBD), which allows us to perform both static and dynamic simulations. More on this in my last point.
• The user creates models using parametric definitions of all components (e.g. gear wheels and shafts), connections (e.g. fixed or sliding) and boundary conditions. From these parametric definitions we automatically generate a CAD model and an FEA/MBD model (with a structured mesh, connections/links and boundary conditions). The FEA/MBD model can be run once it has been automatically created.
• The user, if desired, has access and control over all model levels. Although the CAD and FEA/MBD are created automatically, the user can access and modify all CAD definitions (volumes, faces, etc.) and FEA/MBD definitions (mesh, contacts, boundary conditions, etc.).
• The user can switch fidelity by deciding whether to use 1d (e.g. rods), 2d (e.g. beams) or 3d (volume elements) representations of each component individually. Any combination can be used (e.g. a gear wheel consisting of volume elements and a shaft represented by a beam) and does not require a new parametric definition. Components can even be made fully rigid if desired.
• We have our own (sliding) contact element which was specifically developed for high contact loads. It's highly accurate, even with a course mesh. This drastically reduces computation time. We often see a reduction of computation time by a factor of >100x compared to other FEA software for the same accuracy.
• Because of this speed up, we are able to perform static and dynamic analysis of systems with multiple sliding contacts and with all components represented as flexible parts in a relatively short time.

Our software is not finished yet but works using scripts that we create for various use cases. Before we spend more time creating a user-friendly version with a GUI I would like to hear if these functionalities could be useful in any other applications besides the drive train components we are currently analyzing

As I said, I'm looking forward to hearing your suggestions/ideas. And do not hesitate to ask me questions. I'll try to answer them as best I can.

Hello everyone,

I am currently computing a static simulation of the deflection of an omega shape close section beam (4 points flexural test). And I thought it could be a good idea to do a symetry by the longitudinal axis in order to half the number of elements of the mesh. The thing is that if I do a symmetry in the omega, I am left with an open section which will be far less rigid and more prone to torsion. Do you know if there is a way to do this symmetry and avoid that problem ?

Thank you

Hello everyone,

I am trying to perform a static analysis in a complex part. I have an issue on meshing.

I have a fin structure in one face of the part, each fin has a 1.6mm thickness. If i use 3 or more tet elements alongside thickness, solving time increases alot.

I thought about splitting the fin structure and use shell elements for fins and define contact between the fins and the main body. But im not sure about if this gives somewhat accurate results.

Added an example image to show the split fins and main body.

Is dividing a part to use shell elements and defining contact between them good?

https://preview.redd.it/ifuc9hi1213e1.png?width=436&format=png&auto=webp&s=14c0e32fd7ee62def12207953b79d79c8e759d48

I’ve always been more of a coding person than a GUI person. Although I’ve programmed in ANSYS APDL, it was not particularly enjoyable and the workflows to interface with external programs wasn’t great.

I would like to be able to solve 3D modal analysis problems (resonance frequencies, mode shapes) and wondering for this limited problem domain whether I would be out of my depth trying to program it myself in Matlab.

Breaking it down, I would need:

• A method for defining solid body geometries — I think Gibbon toolbox can do this

• A method for meshing solid bodies — again, Gibbon

• A method to construct the mass and stiffness matrices from the mesh based on the material properties — this might be finicky and hard to optimise but reasonably straightforward logic I think

• Appropriate linear algebra routines to solve the resulting governing equations — I mean, this is one of Matlab’s strong suits, no?

(Gibbon: https://www.gibboncode.org . Although Gibbon interfaces with FEBio, which is open source, I don’t believe FEBio does modal analysis.)

For small problems, the steps above feel like they could be implemented in a relatively straightforward way. But I feel like I have Dunning-Kruger and would trip up before I knew it.

Is the secret sauce in a commercial FEA package the final step of this process, in order words, is it naive to think that a few in-built Matlab functions are sufficient to robustly solve the numerics once a solid body became complex enough?

Simulating Crack Propagation in 2D

Use the Phase Field Method to simulate crack initiation and propagation in a rectangular plate under tensile load.

Implement energy minimization for the crack growth using FEniCS.

Output results showing the crack path and stress distribution.

Let me inform that I have studied one course of computational techniques in undergraduate. Other than that I do not have more experience of FEA. I need to do this for my graduate program application but I am not sure how do I approach this. I have very less idea. But with the help of ChatGPT and study papers, I thing I can pull this up. So if anybody has any idea how can I approach, please let me know. I am a beginner, please do not discourage me.

The title pretty much says it all, I'm looking to design a submarine shell for a uni project and we could/are using Ansys. Still, I was curious if there are specific FEA tools designed for external pressure simulation.

Are there any resources to learn optistruct, hypermesh as student of mechanical engineer?

I am trying to model a 4 points bending analysis on a SENB specimen, which looks like this: (see image)

The problem is that as soon as I compute the interaction, the job gets aborted with the error:
Error in job Job-1: Too many attempts made for this increment

I am not an expert with Abaqus so I don't know what to modify to get the job working. Any help is welcome !

Also Im a newbie to reddit, not sure if I can even post my CAE model here.

https://preview.redd.it/19jr7n0yxv2e1.png?width=737&format=png&auto=webp&s=f0b7178fdc333881cd40d8c9b2240894df7b0bce

www.youtube.com/@learncarbonfiber I post videos about the things I’ve learned while making bikes and the UCI drop test and how my forks have failed/passed

Hello all, my question is to the people working in the industry. How is FEA used in the industry for design, What type of analysis are used the most for designing a product?

Most importantly I want to know how is a assembly of parts analyzed for failure? For eg. a suspension? Are the loads generated in a multi-body software and then a static analysis is performed or the whole assembly is directly simulated in using dynamic FEA or flexible multi-body simulations are used like those offered by Altair Motion solve and MSC adams? Thanks

I am modeling welding on a plate using ABAQUS with the DFLUX subroutine and for some reason the animation time history just stops at increment 584 even though I have 1430 increments. The job status says "complete." The ODB has all the increments in it and when I click on monitor in the job manager dialog box it says complete with all the increments. Not sure how to fix this so any kind of help would be appreciated.

I am currently on a project related to fatigue analysis of a beam using 4 point bending test. I need to input number of cycles. So which step should be used either Static general or direct cyclic? And what are the input parameters to be considered? As I have used direct cyclic step and i need to give maximum number of cycles around 50,000 but my program crashes after several increment and not able to recover. Please help 🙏

I was wondering if anyone has done a finite element cloth simulation. How do you design the cloth and mesh it?

Hi, I'm a student working on Thermal-mechanical coupled analysis in Abaqus but unable to find how it is solving the problem. I couldn't find the equations anywhere. Is there any material where I can get some info regarding what abaqus is doing in the backend?

I am fluent in utilizing the GUI but want to know the deeper details.