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Questions tagged [finite-element-method]

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FEA: What is the difference between a spider of RBE2s and multiple SPCs

I am not sure what the difference is between using a spider of RBE2s. and multiple SPCs across a face. I've heard that the spider is the more accurate method as multiple SPCs make the model overly ...
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14 views

abaqus simulatioon

USING ABAQUS SIMULIA 6.13 hysteresis low cycle fatigue of isotropic and kinematic hardening .I use combine parameters but no yielding occurs and hysteresis force disp loop area is zero .I also need ...
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22 views

how did Abaqus integrate the predefined field (stress) into the FEA formulation

The formulation based on the dynamic virtual work equation is Several boundary conditions can be applied. One of them which Abaqus provided is predefined field (stress). It gives the stress tensor ...
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36 views

Traction Force or Reaction Force

I am doing an FEA of a link plate of a chain drive system. the plate is subjected to traction force at one pin joint this particular link is in contact with the sprocket. it is also in contact with ...
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33 views

Finite Element Code: Convergence issues

I am trying to code a simple FEM problem. A bar is fixed at the bottom edge, and a displacement is applied at the top. I want to apply the displacement gradually , so I have divided it into a number ...
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16 views

Find amount of sliding between 2 surfaces

in my project I am required to find how much two surfaces slide against each other (to see how much it'll will rub against skin). Does anyone know how I can find these results? Thanks
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32 views

Need help with FEA bar analysis problem

I'm trying to solve this which is to find the total deformation of the bar. I'm trying to implement the finite element approach, but I am getting way too large of numbers. Here is what I did in ...
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15 views

What's the methodology for adequate tetrahedralisation?

I'm running a linear elastic solver generating the tetrahedron's using tetGen. It's not clear to me though how one defines what's an acceptable tetra density that provides sufficient accuracy. You ...
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1answer
73 views

FEA: Newton-Raphson algorithm for Dirichlet BC non-linear static analysis

I have a standard non-linear static problem to solve with FEA. I am applying displacement boundary conditions only, no external force. The equation to solve look like these: $K(u)u=R(u)$ Eq(1) The ...
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18 views

Interpolation at a face, Finite Volume Method in Computational Fluid Dynamics

I am learning CFD and I have come across an example in which the thermal conductivity needs to be interpolated at a face between two rectangular cells. The face weighting factor is given as: $$g = \...
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45 views

Analytical calculation vs FEA

In terms of calculated stress, strain, displacement etc which method yields more conservative results. Analytical calculation or numeric calculation?
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30 views

How to define hysteretic damping coefficients for both longitudinal and shear waves in Abaqus?

I am modelling the elastic wave propagating in the damped materials using the hysteretic damping model, but the longitudinal and shear waves usually have different damping characteristics. How ...
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1answer
92 views

What are the governing equations solved in FEA for structural mechanics?

In CFD we focus on the NS equations as the governing equations (together with other equations) and solved them using Some numerical method (usually FVM). What are the governing equations (counter ...
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1answer
63 views

Boundary conditions in a heat transfer problem

One end of a small insulated rod is attached to a support which is maintained at a constant temperature of 473 K,and once the rod has reached a uniform temperature in its entire length the insulation ...
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12 views

how to get laminate stiffness matrices (ABD) in APDL ANSYS

I am trying to perform structural analysis of composite pressure vessel in APDL/ANSYS. I have completed the solution and now I want to extract ABD matrix.Do anyone have an idea about this?
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1answer
89 views

Shape Functions of beam element with 3 nodes (quadratic element)

For a two node beam element there are four shape functions for four degree of freedom: For a straight three node beam element how shape functions are? Please note that beam is straight and not ...
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17 views

Source for learning Functional derivative , Gateaux derivative

I have started doing research in optimal control theory. My area of research is PDE constrained optimization. I am facing significant difficulty in deriving the Gateaux Derivative of functionals ...
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1answer
21 views

Can boundary layer theory be applied in finite element methods as it is applied in finite volume method?

Can boundary layer theory be applied in finite element methods as it is applied in finite volume method? i.e The flow away from the boundary is considered inviscid and solved first, then the flow ...
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1answer
27 views

Finite element method, question about the solver

So I am working with COMSOL Multiphysics and I have a very complex simulation. I have a boundary condition that evaluates to 1 if the value of a variable is 20 and 0 otherwise. I could implement my ...
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1answer
43 views

How to perform 3 point bending test by using force instead of displacement in ABAQUS?

I know you can apply displacement to a rigid body (cylindrical rod) to perform a 3 point bending test in ABAQUS. Is it possible to apply force to the rod (e.g. rod with super high young's modulus so ...
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1answer
47 views

How to introduce the CONSTITUTIVE equation into structure mechanics [closed]

Suppose I have stress and strain relationship and it can be simplified to the equation $\sigma=Function(\epsilon)$. This is the CONSTITUTIVE equation of the material I want to do research. Assume ...
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59 views

How can I do engineering projects for money at home? [closed]

I am a M.Sc. graduate in mechanical engineering and I have experience with engineering software, like MATLAB, CATIA, and ABAQUS. I want to know how I can find industrial projects like finite element ...
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1answer
36 views

Calculate surface area and outward normal of each face(non-planar) for a irregular hexahedron.

I am using the vector cross product to calculate each surface area and thus the outward normal. However, this approach fails when the surfaces are non-planar. So what is the best approach to calculate ...
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1answer
40 views

Stress Tensor decomposition into Compression & Tensile forces

I'm working on a project that does a finite element simulation of a mesh. I can output the stress tensor at each node, but I'm not so sure how to implement failure criteria. If my material is brittle,...
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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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39 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 ...
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33 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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0answers
24 views

Joint Revolute or Fixed?

a shaft is driven by a motor, it is supported in two places by ball bearings and connected in third place by a motor. how can I use this example in Ansys WB? 1. variant : two places, where the bearing ...
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1answer
95 views

Model Reduction - ANSYS

I am trying to reduce my model in ANSYS using Craig-Bampton Method. My ultimate goal is to read system matrices, stiffness, damping and mass matrix with MATLAB. I have been researching for a while, ...
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1answer
30 views

Curve-linear vs. Cartesian coordinate systems: linear-elastic & isotropic elasticity tensor

For shell elements, is the elasticity tensor for linear-elastic & isotropic materials the same in a local curve-linear (convected) system vs. a local Cartesian system? I wonder because ...
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2answers
189 views

Viscoelasticity and Hyperelastic model, history and difference

Actually, I see some papers use viscoelasticity or hyperelastic model for the same materials. It seems to me that those models were invented in different eras, and the hyperelastic is a newer model ...
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1answer
226 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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1answer
43 views

Boundary Conditions fro Static Structural Analysis of a Turbine Rotor Using FEM

I am trying to perform static structural analysis of a turbine rotor which is rotating at a given angular speed, say 1000 rad/s. I also know the pressure distribution from CFD analysis. What are the ...
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1answer
90 views

Should one use multiple elements through the thickness with multiple materials?

To get realistic results from a FEM calculation, it is common (or so I've been taught by someone who may not be up to date) to use at least four or five elements through the thickness of a beam or ...
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34 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?
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63 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 ...
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1answer
139 views

Strain gauge placement to measure a twisting beam

Where is it best to place a strain gauge to measure the twist of a beam? And what type of gauge is best? In my application, I have a small metal part which experiences a twisting and bending force. ...
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1answer
50 views

How to calculate residual strength of a corroded structure from their stress values?

Currently, I have an actual entire corroded bridge model in the FEM analysis in Abaqus I want to estimate the residual strength of this bridge due to corrosion from the output results in the Abaqus, I ...
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1answer
76 views

How to prove that during loading session of glass container, which will happen first - overstressing or buckling - via FEA?

How do I prove that during a loading session of a glass container, between two failure modes, overstressing or buckling, which will happen first via FEA? Is there any scientific way of approaching ...
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1answer
141 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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0answers
48 views

Polyurethane tube simulation in Solidworks [closed]

I am doing polyurethane tube simulation in Solidworks Simulation. I am using material PUR for polyurethane already defined in Solidworks. I have a question about the model type to be selected for ...
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1answer
77 views

Should I apply Force or Pressure, Ansys Static Structural

I am working on a project where I must find the maximum principal stresses on an object subjected to impact loading condition. I know the velocity of the object (the one which will hit the test object)...
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1answer
53 views

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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1answer
194 views

Spatially dependent material property in Abaqus/CAE

I am modelling a plate as 3D deformable solid. My plate has a spatially dependent isotropic thermal expansion coefficient. I have defined this spatial distribution as a Discrete Field in a tabular ...
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0answers
30 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 ...
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1answer
38 views

FEM: What's D in the equation for half band width

In the equation for half band width given below, B = (D + 1)f my textbook states D to be the maximum difference between node numbers in an element and all the elements are considered for its ...
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1answer
29 views

Do finite elements have to be planar?

Is it possible to define a finite element that isn't planar? For example the shell element shown in the picture below...
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1answer
62 views

Cantilever beam with disc at end (structural mechanics)

I am trying to figure out how I can assemble multiple finite elements to obtain the system mass matrix $\boldsymbol{M}$ and the stiffness matrix $\boldsymbol{K}$. The situation is depicted in a ...
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358 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 ...
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1answer
150 views

How to create a non uniform pressure load in MSC Patran

I need to simulate an external pressure load that varies sinusoidally along a circular arc. The sinusoidal variation is with arc length. I know how to create a uniform pressure load in Patran but do ...