Questions tagged [finite-element-method]

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407 views

Does welding two metal parts together increases or decreases the strength locally there?

I have a structure made out of steel consisting of many thin rods and some of them are welded to each other. I conducted a simple FEA static structural analysis to determine if the structure would ...
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2answers
37 views

Why does it take lesser iterations for a stiffer model in my FEA than a less stiffer model to converge?

I am currently using ANSYS FEA software and I conducted a simple geometric non-linear analysis of two same shaped bodies, but different cross sectional areas; one being quite bigger than the other. We ...
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11 views

Abaqus CAE - how to measure/calculate area of a certain threshold within the Visualisation module?

I have been using Abaqus CAE to model a CT-specimen being pulled apart, in order to observe the resultant plastic zone shape around the crack tip. To reduce computational cost, I have modelled a ...
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21 views

Why the model with rebar layer shows one sided plastic strain in Abaqus?

Using the damaged plasticity model, I modeled a concrete coupled shear wall in Abaqus, once with discrete rebar and once with rebar layers for the slab. I used the general static solver to run the ...
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4answers
103 views

When a jet engine propels an aircraft forward, where does the thrust force on aircraft act?

I am trying to model the mount structure of an aircraft onto which a jet engine is attached, in Finite Element Analysis. Since I am only concerned about the local mount structure, I have isolated it ...
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3answers
87 views

Why is my FEM analysis producing unusually-large stress results?

This is my first time performing an FEM analysis, and I'm using the Ansys Workbench and Mechanical software. My situation is pretty straightforward--it's a straight beam that is fixed at one end and ...
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2answers
134 views

What is stress stiffening in Finite Element Analysis?

In a Finite Element Analysis, if we turn ON the geometric non-linearity, it also takes into account the stress stiffening if any structure is undergoing it. That is what I have read in the literature. ...
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14 views

compute nodes and members according to stiffness matrix of truss (inverse the direct stiffness method)

I am familiar with the direct stiffness method (truss), and programmed it from scratch in Java. The member stiffness matrix is determined by any link (member) and the nodal coordinates. The global ...
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35 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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65 views

Can anyone help validate my FEM results?

Quick background, I'm a programmer not an engineer, but I do have some background in physics and maths - I understand I may have been a little ambitious with this project, but its my master ...
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1answer
80 views

Is the calculated shear strain in a beam, engineering strain or tensorial strain?

Recently I came across a FEM code of a linear deformation beam element, and it made me wonder what is the correct relation between shear stress and shear strain in a beam element. In the beam element ...
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26 views

Computing forces and moments acting on the sides of a rectangular shell element from corner forces and moments

I have a FEM program for shell elements implemented through the direct stiffness method. Using this program corner displacements of shell elements due to external loading are obtained through the ...
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0answers
21 views

Cannot measure reaction moment (RM) in Abaqus

I am trying to calculate reaction forces/moments in a simple Abaqus model. I started with a simple static model of a cylinder with applied loads on one end, while the other end was "Encastered.&...
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1answer
34 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 ...
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2answers
53 views

What is the difference between Frictional non-linearity and Geometric non-linearity in FEA? (In terms of Stiffness matrix)

For geometric non-linearity, we know that as the geometry changes during the analysis, the global stiffness matrix changes since it already is a function of geometry of the structure. What I want to ...
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27 views

How do I find the buckling strength?

I am running something called cell periodicity study in comsol, which finds the material properties of a model. It is done by applying a uniaxial compression load, and performing a nonlinear buckling ...
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1answer
27 views

Linear Nastran model not converging

I am running a SOL 101 linear statics FEA. If I fix down the whole geometry it converges. But anything less than around 90% fix down and it will sit there crunching away at the numbers forever. This ...
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1answer
32 views

Why is plastic deformation a non-linearity if I am using Bilinear hardening to model it in FEA?

Attached you may find a picture for isotropic bilinear hardening up until the ultimate tensile strength. The first line is the elastic region while the second one is plastic. I couldn't understand ...
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43 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). ...
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0answers
19 views

Why do we need to have perturbation in our system to do buckling analysis? [closed]

Do we need it for both linear and nonlinear system?
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1answer
40 views

Why should I use a contact between two glued bodies in FEA when I can directly merge the mesh nodes between them?

So I am using ANSYS to conduct a FEA analysis. I have two options to built a connection between two bodies; first is I can use a contact (like bonded) between the touching faces and the other option ...
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3answers
60 views

FEM degrees of freedom

Consider a "beam". In order to perform modal analysis using the finite element method, the beam is meshed with 2nd order hexa elements. The total count of nodes is 1280. The same beam can be ...
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0answers
39 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 ...
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24 views

Perfectly Matched Layer (PML) for Plates in COMSOL

I am modelling infinite plate domain in COMSOL for frequency simulation. I need to apply absorbing boundary conditions all around the boundaries and I could not find PML option for plates. Could ...
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0answers
25 views

Solver cannot find any eigenvalues for linear buckling analysis [COMSOL]

I am trying to do a simple linear buckling analysis, where one end is fixed and the opposing end has a prescribed displacement of -0.1m in the x-direction that compresses the structure. Solver cant ...
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2answers
126 views

Which yield strength should I use in FEA in ANSYS; Engineering or True?

Attached is a figure to illustrate the difference in the value of yield strength as observed from the true stress/strain curve and engineering stress/strain curve. While conducting FEA in ANSYS for a ...
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3answers
67 views

Boundary condition at supported end of a rod

I have one end of a rod held in a hole of a 'rigid' part with no clearance, while the other end is loaded with a force. I have shown 3 simple reaction-force models in the picture. If my intent is to ...
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2answers
115 views

Calculating the von mises stress in a 3D beam when given stresses and moments on both ends

I want to calculate the von mises stress in a given structural member. I want to generate a von-mises plot from this data. The forces are according to the local coordinate system of the beam. Also, I ...
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1answer
83 views

Modeling torque as surface pressure

Consider a rod with a length of 150 [mm] and a diameter of 44 [mm]. At the left boundary the rod is fixed to a wall. At the right end a torque of 1000 [N m] is applied. The remaining boundaries are ...
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0answers
15 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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2answers
46 views

Computing the stress field of a structure made of 4-nodes shell elements (accounting for membrane action, bending and shear)

I am trying to implement my own FE code for shell structures. Most literature provide formulations and strategies on how to compute shell element stiffness matrix. I can already compute deformations ...
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1answer
20 views

Frame element stiffness with non-axis-aligned anisotropic area moment of inertia?

I've found equations for the $12\times12$ symmetric stiffness matrix for an element of a frame (a truss with welded joints): http://what-when-how.com/the-finite-element-method/fem-for-frames-finite-...
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0answers
25 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 ...
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38 views

Heat Transfer FEA with matlab

I have to write a matlab code using finite element method to solve this problem. I have solved it as follows but I dont know how to apply it in matlab. I have to write a matlab code using finite ...
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32 views

Solidworks 2D static nonlinear simulation convergence problems

I'm trying to do the following 2D nonlinear static simulation in SolidWorks (video was made in Ansys): https://we.tl/t-m3XQrUZZ5U However, I've been getting these convergence problems I can't seem to ...
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11 views

Magnetic Wall HFSS

I'm new to RF engineering and I want to ask how to draw magnetic and electric wall in HFSS software? I know magnetic Wall means open circuit in circuit model and electric wall means short circuit, but ...
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2answers
40 views

Modeling composite material fibers orientation in a FEA

I am looking for guidance for analyzing composite materials that are reinforced by fibers of some sort. A good mental model would be bars of steel in concrete. The concrete will have its own physics ...
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0answers
23 views

Find orientation of reference nodes in Abaqus

I am constructing a simplified model of a pontoon-supported floating bridge in Abaqus. I have chosen to represent the pontoons as one-noded user-elements defined from the mass and stiffness matrix for ...
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1answer
49 views

Ripple tank simulation for simulating light waves? [closed]

Can anyone help shedding some light on how ripple tanks are programmed? example I'm looking to simulate light waves, to perform theoretical calculations, as opposed to for just visual effect. The ones ...
3
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0answers
26 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: ...
2
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1answer
70 views

ANSYS: Why do I have a choice of choosing TOP/BOTTOM under contact/target shell faces?

When ever I try to use a surface to surface contact, i.e. 2D shell elements to 2D shell elements, under the option Contact/Target shell face, either I can pick TOP or BOTTOM. Why is that? How is that ...
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45 views

Craig Bampton Model Order Reduction on Ansys

I am in the process of modeling a component as a flexible body in Simscape Multibody environment (Simulink). I need to superimpose rigid body model with the deformation model. The deformation model is ...
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59 views

Simscape Flexible body - modeling a busbar as a flexible component on Simscape

I am trying to model a copper busbar as a flexible body for simulating it in the Simscape Multibody environment. I have built the model, but I am failing to generate the flexibility. I will describe ...
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0answers
51 views

DC and AC Simulation on Ansys Maxwell for calculating the core and winding losses in an Inductor

I want to simulate the core and the winding losses in an inductor using Ansys Maxwell when imprinted with a triangular pulse(positive RMS Current). I am doing a DC simulation to get the inductance ...
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2answers
46 views

Why do I see stresses on the fixed support face of a solid body in FEA?

Below, I have shared pictures of a simple model in FEA. As it can be seen that the face onto which the fixed support is applied, there exists Von-Mises stresses. I cannot comprehend why. Since the ...
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1answer
32 views

In FEA, why is the stress at an interior angle (<180 deg) is a singularity and an exterior angle (>180 deg) it is not?

If you observe the attached figure, I heard some FE analysts say that the stress at the interior corner is always a singularity (but its intensity depends on the value of interior angle) but the ...
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2answers
245 views

Are there any instructions on how to install and run Natran-95?

there is a source code for Natran-95 on Github. I need to install it on Window 10 but searching on the web there is no clear tutorial on installation. while I click on the nastran.exe on this package ...
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22 views

How To Assign Different YoungsModulus To A Multi-material Mesh?

I have a mesh designed in Blender and I am using SOFA Physics engine simulator (based on FEM), however, I don't know how to assign different YoungModulus to a mesh like mine since each parts are ...
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2answers
44 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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1answer
128 views

Stress Concentration Factor – Why a Specific Range?

I was trying to find the stress concentration factor for a specific situation and I found two different resources for it. Ref: Shigley's mechanical engineering design Ref: Roark's Formulas for ...

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