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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 ...
imacube's user avatar
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8 votes
0 answers
677 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 ...
Ant's user avatar
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6 votes
2 answers
369 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-...
user33108's user avatar
5 votes
1 answer
132 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 ...
Anonymouse's user avatar
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 ...
Graviton's user avatar
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4 votes
2 answers
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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 ...
Josie Colclough's user avatar
3 votes
0 answers
50 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 ...
Worldsheep's user avatar
3 votes
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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: ...
Евгений Павлов's user avatar
3 votes
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36 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 ...
Евгений Павлов's user avatar
3 votes
0 answers
155 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 ...
FliegenderZirkus's user avatar
2 votes
2 answers
191 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[]=...
Terry's user avatar
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2 votes
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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 ...
MechFlag's user avatar
2 votes
0 answers
142 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 ...
BetterSense's user avatar
2 votes
0 answers
109 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 ...
Brendan McBreen's user avatar
2 votes
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53 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?
G.David's user avatar
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123 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?
Balázs Búr's user avatar
2 votes
0 answers
809 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 ...
Schneider's user avatar
2 votes
1 answer
171 views

Most efficient fillet design given an envelope (for stress)

If one has a specified allowed X length and Y height, into which a fillet can be placed to reduce stress concentrations, is there an equation which can be used to determine the optimal shape of the ...
user1814893's user avatar
2 votes
0 answers
791 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 <...
SAndroid's user avatar
1 vote
1 answer
60 views

What is the meaning of the traction continuity condition in the generalized momentum balance (continuum mechanics)?

In Nonlinear Finite Elements for Continua and Structures by Belytschko and al. it is stated: As we have already noted, the strong form, or generalized momentum balance, consists of the momentum ...
Paolo Secchi's user avatar
1 vote
2 answers
119 views

Finite Element Method for Spherical Objects

I am familiar with the procedure of the FEM for simple planar objects like truss and etc. but my question would be whether it would be possible to use this method to calculate the stiffness or ...
farhad_hep_81's user avatar
1 vote
0 answers
86 views

How can I recover the deformation gradient from the finite element strain result

I have performed a finite element simulation which corresponds to the example in https://de.wikipedia.org/wiki/Deformationsgradient#Beispiel . The result from the theory in wikipedia is the following (...
pytunia's user avatar
  • 11
1 vote
1 answer
80 views

Why do Eigenmodes of a rigid system also diagonalize the Mass and the stiffness matrix seperately?

To set up my question, I will briefly recap the derivation that is usually given for eigenmodes of a system: If there is no force present, and a body is described by a vector $u$, then the equations ...
Quantumwhisp's user avatar
1 vote
0 answers
238 views

Lifting a table using linear rails and linear actuators

I'm trying to design a coffee table for a tightly constrained space that can lift up to become a dining table. I've drawn the CAD for this design, but I'm concerned that the moment arm on the linear-...
Raymond Zheng's user avatar
1 vote
1 answer
36 views

Displacement vectors and linearised angles vectors from local finite element frame to rotated global frame

$s=R\tilde{s}$ is fine, but why $\theta=R\tilde{\theta}$? Namely: why vectors of linearised rotations $\theta_i$ and $\theta_j$ (at nodes $I$ and $j$ respectively) are rotated like they were vector ...
Fabio Carfora's user avatar
1 vote
1 answer
84 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, ...
SNIreaPER's user avatar
1 vote
2 answers
66 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 ...
Goli's user avatar
  • 11
1 vote
0 answers
59 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 ...
ap21's user avatar
  • 163
1 vote
0 answers
74 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). ...
Material scientist's user avatar
1 vote
0 answers
45 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 ...
Material scientist's user avatar
1 vote
2 answers
306 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 ...
Sady's user avatar
  • 11
1 vote
0 answers
517 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 ...
Barrett Cloud's user avatar
1 vote
1 answer
253 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 ...
DMC05's user avatar
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1 vote
0 answers
112 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 ...
Frederik Christensen's user avatar
1 vote
0 answers
116 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 ...
FEA42's user avatar
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1 vote
0 answers
41 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 ...
Siddharth Vohra's user avatar
1 vote
1 answer
218 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 (...
Rémy Martin's user avatar
1 vote
0 answers
81 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 ...
Virgil 11's user avatar
1 vote
0 answers
101 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 ...
Jeroen's user avatar
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1 vote
0 answers
165 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 ...
jv7's user avatar
  • 11
1 vote
0 answers
51 views

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....
user586228's user avatar
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 ...
Denis's user avatar
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1 vote
0 answers
479 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 ...
Jack Boggs's user avatar
1 vote
0 answers
104 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-...
Jzuken's user avatar
  • 111
1 vote
1 answer
953 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 ...
Tanner's user avatar
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1 vote
0 answers
213 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 ...
user17189's user avatar
1 vote
1 answer
577 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 ...
remi's user avatar
  • 111
1 vote
0 answers
189 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 ...
mike's user avatar
  • 161
1 vote
0 answers
71 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 ...
Ryan Larson's user avatar
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 ...
BJC's user avatar
  • 49