Questions tagged [finite-element-method]

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ANSYS APDL Shape memory effect option of SMA not working

I am trying to define the material properties of a shape memory alloy material in ANSYS APDL V15. There are material properties for Superelastic materials (SUPE option) and material properties for ...
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8 votes
0 answers
603 views

Incompressible 2D pressure-driven flow: for Navier-Stokes equations in nondimensional form, how should I express pressure boundary conditions?

*I have updated this question. I'm using two codes for modeling incompressible, two-dimensional flow out of a tank. My fluid dynamics experience is pretty basic; I'm using the codes to understand a ...
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6 votes
2 answers
278 views

How to analyze a bent beam: Stress concentration?

I am analyzing a beam, that has a bend in it. Intuitively and inspecting FEA results using a linear solver, there is a stress concentration at the bend of this I-beam. The part was not a straight I-...
5 votes
1 answer
111 views

PATRAN Order of Operations

To preface this question, almost all of my FEA experience has come from SolidWorks, so I haven't had to deal with these types of problems. I'm designing a truss structure in PATRAN composed of 1D ...
5 votes
1 answer
1k views

How can we derived the equivalent Lumped Mass Model for irregular building and how to calculate the errors?

Intuitively, building can be represented as a lumped mass model ( the taller the merrier!): Assuming a building is a lumped mass cantilever column also makes the global stability checks easier ...
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4 votes
2 answers
689 views

Interference fit problem in ANSYS Workbench 16.1 - how do I get rid of pressure/displacement raisers?

I have an interference fit problem of two perfect cylinders modelled in 2D using symmetry. The overall interface pressure is around 20MPa lower than the hand calculations and I get non-uniform ...
3 votes
0 answers
33 views

Model order reduction - Criag Bampton method

I am trying to understand how model reduction works, more specifically the Criag Bampton method. I would like to implement this method on a simple model in Python. I have been reading the following ...
3 votes
0 answers
32 views

How quadrilateral elements represented in most FEA solvers for structural mechanics problems?

How quadrilateral elements represented in most FEA solvers for structural mechanics problems? I know that Nastran-95 represent quadrilaterals for membrane and bending elements as a set of triangles: ...
3 votes
0 answers
35 views

How do FE solvers solve the case of panel buckling under pure shear?

How do FE solvers solve the case of panel buckling under pure shear? The main problem is that global matrix of initial stess is singular in that case. One method is to apply some forces that shear is ...
2 votes
2 answers
76 views

Imposing/ensuring a constant mass flow rate in turbulent flow simulation

I'm trying to simulate using Finite Elements (non commercial software) the Tube Bundle benchmark problem: http://cfd.mace.manchester.ac.uk/ercoftac/doku.php?id=cases:case078&s[]=tube&s[]=...
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2 votes
0 answers
27 views

Narrowing down injection moulding material selection

How do I narrow down specific values when selecting a plastic for injection moulding? My part is uniform in wall thickness and thins out where a hinge a present. Properties: Will not go under many ...
2 votes
0 answers
98 views

Optimum spoke shape for wheels made of solid material

Currently I am designing a bicycle sprocket to be laser-cut out of 3mm steel. Steel is heavy, so I want to make some lightening cut-outs, and I want to optimize the shape of the cutouts. I will ...
2 votes
0 answers
67 views

Solidworks Simulation- Large displacement with Inertia Relief

I'm trying to use the Solidworks simulation package to solve for the stresses inside a body as it accelerates (very rapidly). Because I expect some small features to deform quite a bit, I need to use ...
2 votes
0 answers
35 views

Can the critical buckling load from non-linear FE calculation be higher than the one from linear?

Let's consider a FE buckling calculation without plasticity. Is there theoretically any chance that the non-linear analysis will give a higher buckling load than the linear one?
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2 votes
0 answers
71 views

Assign a name to surface in CAD STEP file

I have a CAD model designed in FreeCAD and need to export it to a STEP file (neutral CAD format) to be used in numerical anaysis software. I would like to assign names to selected surfaces in order to ...
2 votes
0 answers
79 views

Force exerted on the CPU socket by heatsink

I am currently designing a replacement bracket for AM4 CPU coolers that will be compatible with different cooler models and allow them to be installed facing different directions, as AM4 socket is non-...
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2 votes
0 answers
77 views

Bolted joint junker test with finite element method

Anybody knows a tutorial to make a finite element analysis for bolted joints like junker test(fastener vibration) in Solidworks or Ansys?
2 votes
0 answers
710 views

How does Abaqus calculate reaction force?

I wrote a UEL for one element and compared to a reference UEL (FEM), where the results agreed satisfactorily, except the reaction force. The stress, strain, strain energy all were pretty accurate. I ...
2 votes
0 answers
693 views

how to release specific degree of freedom in ANSYS Workbench?

I'm designing a truss which has 9 elements in ANSYS Workbench. since it is a truss, all of the elements are truss elements and can not tolerate momentum. I used <...
1 vote
1 answer
49 views

Are there any advantages of using BEM for contact problem over FEM, apart from lesser computational cost?

FEM - Finite Element Method BEM - Boundary Element Method If we had access to "enough" computational resources (to discretize the entire volume domain in FEM to the same degree of fineness, ...
1 vote
2 answers
48 views

Is there a specific way to simulate porous structures?

I tried to simulate an axial compression test for a lattice (porous) structure but It takes too much time and it doesn't give me the right answer (when I compare with experimental results). So, I was ...
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1 vote
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42 views

Does numerical dissipation in FE simulations affect system's elastic energy? Does it depend on thickness?

I am running a finite-element simulation in Abaqus, for which I also have a theoretical model. To be precise, I am simulating wrinkling in a thin annular sheet, with shell elements. The model makes a ...
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1 vote
1 answer
55 views

Why is the amount of force/moment transfer occurring between bodies in FEA is independent of mesh size?

So I read somewhere that the mesh size won't effect the amount of force transfer occurring between bodies if several bodies are in contact, and a global force is applied somewhere. I wanted to know ...
1 vote
0 answers
55 views

Do these linear vs nonlinear buckling plots make sense?

I am doing linear buckling analyses (where everything is linear), and nonlinear buckling analyses where you have nonlinear geometry enabled and nonlinear material behavior (hyperelastic material). ...
1 vote
0 answers
41 views

(Follow up) Can a thicker model giver a lower critical buckling load?

I present three seperate models with thickness of t = 0.005m, 0.01m and 0.025m respectively, all have a forced displacement of -0.01m in the x-direction, and fixed on the other end. As you can see the ...
1 vote
2 answers
123 views

FEM of beam with unsymmetrical UDL

I have two different UDLs for 6.5m and 3m spaced side by side on a primary beam. If I were to calculate the FEM of this beam, how should I proceed as there're no formulas for situation particularly ...
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1 vote
0 answers
221 views

How to determine the stiffness matrix for finite element matrix

I'm having difficulty understanding how the stiffness matrix for finite elements is obtained. I am only having a difficult time understanding how to obtain the matrix values for K from the given ...
1 vote
1 answer
142 views

Analytical solution of thermal stress in a bi-metallic cylinder

As a side project I have looked to solve using Python an analytical solution for one-dimensional transient heat transfer in a thick cylinder with cladding on the inside surface, wherein the fluid in ...
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1 vote
0 answers
64 views

Pin connection on beam - FEA analysis

I am establishing a MatLab FEA code for determining the stiffness of a structure. Diagram of the structure is added below. I have established a code for determining the stiffness of the structure, but ...
1 vote
0 answers
64 views

How accurate should Rayleigh-Ritz approximation be?

For a simply supported beam with a UDL, with boundary conditions of X=0, V=0 & X=L, V=0. Using a cubic trial function. $$V=a+bx+cx^2+dx^3$$ The following curve is obtained (Red Line). It is ...
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1 vote
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31 views

Ansys Fluent - Turbulent model and mesh

I am currently working on a project that involves CFD simulation on ANSYS and i need some help as it has got me stuck. I am designing a faucet atomizer and it's functioning is similar to a nozzle. I ...
1 vote
1 answer
108 views

How to repeat on ABAQUS FEM simulations without reloading the mesh?

I would like to perform several FEM simulations on a given mesh with ABAQUS, where only the orientation of an element set would change in between. Currently, I'm just generating several inp files (...
1 vote
0 answers
58 views

Linear FEM: Infinitesima Strain tensor at different element mesh

Hi guys, I am solving an exercise for a course of Computational Continuum Mechanics. Briefly, my question is how can i compute the infinitesimal strain tensor at different nodes of the finite element ...
1 vote
0 answers
66 views

In Nastran, how to ignore fatal error due to failed convergence and move on to next subcase?

At the moment the whole analysis stops when 1 subcase fails to converge. How can I keep the analysis going such that all subcases are are run, even if they all might produce an error? I'm pretty sure ...
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1 vote
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92 views

Extracting load info on Abaqus with Python

I have a model on Abaqus that I've managed to run some 85 jobs on manually. Between jobs, only the loads vary, and I select these loads by resuming what I need and suppressing what I don't with my ...
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1 vote
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What is the difference between $K$ ,$K_{IC}$ and $K_t$?

I have seen three representation of stress concentration factor values $K$,$K_{IC}$ and $K_t$ now all that I know is $_I$ in suffix represents opening mode of crack.The suffix $t$ stands for tip....
1 vote
0 answers
12 views

Is it possible to change a 'relaxing length' of edges for 8 node hexaedral element in 3d FEM

I am using 3D FEM with 8 node brick element to model a certain type of growth/expansion, which is not a plastic deformation. First, I apply a pressure/load and I get displacement and new position of ...
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1 vote
0 answers
295 views

Modelling radial Stiffness in Patran Usinf CBUSH Element

I am currently working on a project using MSC Nastran and Patran trying to model only radial stiffness between two hollow cylinders. I have been able to idealize a connection which has both radial and ...
1 vote
1 answer
818 views

Meshing Complex models in abaqus

I'm trying to mesh a model of a morphing wing in Abaqus and have been running into issues. It was recommended that I partition the model into smaller parts, but it seems that the more I try to ...
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1 vote
0 answers
144 views

Modeling Rotation and Translation of surface B.C. in Abaqus

I am trying to model a test which has grips that can translate in X and Y directions, as well as rotate. I have been trying to model this using constraints and a reference point but have not been able ...
1 vote
1 answer
478 views

Debugging Ansys ACT C# Extensions

I'm using the Ansys ACT Api with C# to create an extension for Ansys (Mechanical). When developing the extension I need to build a dll file from C# code (using Visual Studio). My problem is that ...
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1 vote
0 answers
164 views

Modelling acoustic instruments — predicting frequencies, decays, levels, and phases of modes of a circular membrane (drum head)

I have been working on some acoustic synthesis software for modelling several acoustic instruments. I am using the principle of modal synthesis, where every mode of vibration is individually ...
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1 vote
0 answers
61 views

Where to fix part in moment setup for FEA

I'm working on a project that involves supporting a distributed load on a bar that is held up by a moment at one end of a lever arm. My goal is to assess how much the bar bends under the distributed ...
1 vote
0 answers
30 views

Searching for Anterior Cruciate Ligament MRI Images for Finite Element Model.

I'm searching for 3D MRI images for generating an mesh to be used in a Finite Element Modeling project. My group has access to a low-resolution CT scan and cadaver knees, but we don't have any good ...
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1 vote
0 answers
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How to convert solid part to shell part in Abaqus?

I want to compare the same model with solid shape and shell shape, since my model is big, I am wondering if there is a way to convert the solid part into a shell in Abaqus easily without creating a ...
1 vote
1 answer
2k views

Calculate the Euler buckling load of a column using the finite element method

I am trying to find the buckling load of following column: I started from the system of equations $P = (K + K_g(N))U$, where $K$ is the stiffness matrix of a single 2D frame element and $K_g$ is the ...
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1 vote
0 answers
474 views

Beam element stiffness matrix for variable area cross section with mass and shear center not coinciding

I would like to find the full (12 by 12) Timoshenko beam element stiffness matrix for a variable cross section with mass center axis and elastic center does not coincide. I have the full stiffness ...
1 vote
0 answers
32 views

Nitinol FEA using Advanced Simulation NX

Is there a tutorial on how to do non-linear FEA using Siemens Advanced Simulation NX (not remap) with Nitinol, preferably using sol 601. An example would be very helpful, I searched online but most ...
1 vote
0 answers
1k views

Creating a custom field output in ABAQUS

I want to create a custom field output in ABAQUS. For the purpose of proof on concept, I want to display the maximum shear stress as calculated from the Mohrs circle, as discussed here for a 2D shell. ...
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1 vote
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External FEA confirmation

The exact question Assuming you have outsourced a FEA of a structural design (steel tubes and sheet metal, bolts and welds design): What would you look for in the report to have confidence in the ...
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