# Questions tagged [finite-element-method]

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17 views

### How to model fibre reinforced concrete on LUSAS?

As part of my dissertation, I need to cross verify my finite element analysis results using LUSAS using some experimental results, and although i can find some stress-strain relation in some articles, ...
14 views

### thermoelasticity problem with FEM

Hello I want to find distribution of temperature, and stress in cylinder with inner and outer temperature and pressure , I used linear elements with 3 nodes and wrote matlab code, moreover I want to ...
15 views

### Problem with model constraints in ANSYS mechanical

I've been trying to run an analysis of the geometry in the attached images. The geometry consists of an inner tube with protrusions along an axis (this axis is not parallel to the Y axis) and an outer ...
16 views

### Modifying Johnson Cook Model in ABAQUS simulations

I am currently simulating a high strain rate impact of commercially pure nickel and found a constitutive equation in DOI: 10.1051/jp4:2006134015. They have a modification of the Johnson Cook model to ...
17 views

### COMSOL multipysics - thermal stress for cubeSat in low earth orbit eigenvalue slover error

I'm using COMSOL version 6.2 for my simulation work. I'm dealing with Heat Transfer involving Radiation and Thermal Stress in solids phisics only after inserting all the constants and boundry ...
68 views

### Finite element method approximation

In the picture above, we have on the left a figure representing spatial element, and on the right a figure representing reference element. The type of element used in the method here is a linear ...
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### Case studies in Carbon Fiber composite tubes to verify FEA

Whenever I build a model of something new, I like to have some analytical results that I can compare with my model so I can reassure myself the model is correct. I have some resources that show me ...
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### Is it possible to use the results from Abaqus Standard as a predefined field in Explicit analysis? If so, how is the time mapped between the analysis?

I have nodal results from an Abaqus UEL subroutine, where I am solving coupled heat and moisture transport. I have three degrees of freedom in this analysis and several more state variables. I want to ...
17 views

### How to suppress longitudinal stress waves in a beam in FEA

When simulating a bending beam in FEA mimicking the textbook model and approach, unwanted stress waves appear. How to suppress longitudinal stress waves in a beam in FEA? To add friction/damping?
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23 views

### Is it OK to separate fire and structural analyses when analyzing a fire induced building collapse?

This is from NIST NCSTAR 1-6 It seems to me there are problems with this approach. The heat distribution depends on fire spread and ventilation paths, which in turn depend on the shape of tjr ...
36 views

### Finding the best fit between Ansys model results and measurd values to optimize the parameters

I have the final element model of an experimental rig respresenting a vibrating system. The time domain results from both are known. I need to reduce the error between the results/find the best fit ...
73 views

### Can someone help me with solving this beam problem using Rayleigh Ritz Method, my trial function is not working

The question is there is a two element beam joined together. The first element is 5m long and the other is 4m long. At the outer nodes there are roller supports and at the middle point where two ...
1 vote
96 views

### Why is FEA used for structural analysis?

Is there a reason for using FEA to perform structural analysis over for example Finite volume method for example?
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### When to use MPC Contact formulation in Ansys?

I was suggested to use MPC while analysing with beam elements. It's for an analysis of a table to be used in harsh shock conditions.
38 views

### COMSOL modelling wicking of paper in 3D

I am trying to model wicking of paper in 3D, by following the tutorial for paper wicking in 2D on the COMSOL Application Library , but ran into this error: Undefined variable. Variable: phtr.pc_s2 ...
24 views

### How can I determine the best thicknesses of a circular plate to achieve minimum weight and high strength?

I want to design a circular plate made from iron ductile material, So I want to determine the best thicknesses of the profile (t1,t2,t3,...etc) as shown in the image tyo achieve the best plate weight ...
319 views

### What is the difference between maximum principal strain and maximum in-plane principal strain?

For the purpose of answering/explaining this, it does not need to be restricted to strains (i.e., it can be stresses too). I am mainly trying to understand when to use which one (i.e., if I am ...
40 views

### FEA meshing of irregular geometry

I work on the simulation of sand particles and usually use tetrahedral free-meshing to represent their complex geometries for finite element analysis. I have recently spent some time looking into ...
42 views

### Deformation Due to Material Removal and Residual Stress

Suppose I have a piece of metal (of arbitrary geometry) with some residual stress profile. I then remove a chunk of the metal and the piece of metal deforms (due to the residual stress). For ...
• 15
19 views

### Checking if a Residual Stress Field Achieves Mechanical Equilibrium

Suppose I told you the Cauchy Stress Tensor at every point inside a chunk of metal. And, yes, I know this means that I would need to tell you about an infinite number of points - let's ignore that ...
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67 views

### Beam deflection for FEA model validation

I'm trying to validate an FE model that I'm using by comparing to a simplified analytical solution to the problem. The part I'm analyzing is a lug that is constrained on one end and has a point load ...
• 1
68 views

### Creating a state-space representation (.m format, Matlab) via Simcenter 3D (NASTRAN) using Component Mode Synthesis Reduction

I'm trying to create a state-space representation of my FE-model using a "Component Mode Synthesis Reduction" (general form of Craig-Brampton reduction). The picture underneath shows (...
21 views

### Specific Heat, Pore Fluid In ABAQUS

I want to model a problem that the theory behind is in the "Coupled Pore Fluid Flow and Stress Analysis" context that there is in the ABAQUS online documentation, version 2022. The link to ...
36 views

### New to AutoCAD, trying to accomplish a simple task of trying to simulate how much force can a U channel withstand

Sorry if my question or parts of it seem vague or stupid, I'm fairly new to mechanical engineering. I'm part of a team that is building a simulator platform and I am mostly at the helm of the software ...
1 vote
77 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 ...
34 views

### Define material from Ogden–Holzapfel two-fiber strain-energy function in Ansys

I'm trying to do a FSI simulation with properties, described in this paper and for the structural properties, the authors use an Ogden–Holzapfel two-fiber strain-energy function to describe the solid ...
16 views

### Aligning stresses from one element to another from FEM

I have a Finite Element Model (FEM) and from this model I want to transform the stresses of one element such that they align to another element's axis. Element A: Centroid: [7195, 5151, 479] ...
1 vote
131 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 ...
105 views

### Iterative Method through FEM

Due to reasons, I cannot fully describe the process explicitly so I will be using substitutes to represent the variables. Nomenclature: $\bar{X}$ - independent variable 1 $\bar{Y}$ - independent ...
47 views

### Is there a way to program a buckling analysis of an arbitrary shape, using a standard programming language/libraries (not Abaqus)?

I am trying to develop a program in Python that runs a few different basic analyses for optimization like minimizing compliance and buckling. I want to use machine learning to try to develop a fast (...
25 views

### Simulating the Impact of Bicycling on Hip Joint Cartilage

Sorry if this question comes off as obvious. I have more of a biology/clinical research background, and I have almost 0 experience with FEA. I have 50 sequential data points of the hip joint angles of ...
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53 views

### Benchmarking Geometrically Exact Beams: Clarification Needed on Material Density?

In an early paper on Simo, I came across an example titled "Cantilever 45-degree bend subject to fixed and follower end load". A force of $600N$ and $300N$ was applied at the end, resulting ...
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### Boundary conditions for Clevis fork (linear elasticity)

consider the Clevis fork domain (see here for an image https://www.traceparts.com/it/product/camloc-motion-control-h1-stainless-steel-clevis?CatalogPath=TRACEPARTS%3ATP01001005&Product=10-12112014-...
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### Clarification on the location of stress and strain output value in Abaqus

Today, I had a discussion with my teacher about the location of stress and strain output in Abaqus. I believe that Abaqus outputs stress and strain based on Gauss integration points. However, my ...
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### Designing a Torsional Rotary Flexure - Finite Element Freeware?

I am interested in designing and building a flexure based telescope tracking accessory. The core of the design would be what I think is called a "rotary flexure" or "Twist-it" or ...
140 views

### Determining the critical load of a fixed beam with non-uniform cross-section?

I am a computer scientist, not a mechanical engineer, so it is absolutely possible that I am missing some basic understanding here. I have a beam that is fixed in both ends and my goal is to ...
• 101
94 views

### What are the possible reasons that a finite element simulation would converge successfully at larger element sizes but not at smaller element sizes?

When running a finite element simulation that converges at larger element sizes but not at smaller element sizes, what are the potential sources of the problem? I am wondering in what areas must a ...
• 1
23 views

### FEA of Rectangular Body Under the Effects of Combined Rotational and Translational Shear

First image is model setup. Clasp is rigidly constrained at top surface. Rectangular beam is affixed to clasp at clasp faces (locally constrained), by way of adhesive pads (second and third images). ...
31 views

### Theoretically when a homogeneous isotropic bar is subjected to axial loading, does it fail in shear?

I m referrencing James M Gere, Timoshenko Mechanics of Materials Chapter 2 Page 106. The book talks about effect of uniaxial load on a small element that is inclined in one axis. So my question is if ...
100 views

### Comparison between hand calculations of a continuous beam with FEA simulation (Solidworks)

I've seen many videos and books where statically determined beams' hand calculations are checked using FEA. But why is it that FEA results don't match the ones obtained using hand calculations (in ...
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1 vote
330 views

### A benchmark to check the validity of a finite element analysis

Is there any well-established benchmark to test the validity of a finite element analysis, i.e. FEA? For example, a 3D model with specific loading and boundary conditions. Along with the expected ...
• 151
1 vote
47 views

### Residual Stress Induced By Shot Peening

I'm interested in the residual stress profile induced by shot peening. Most of the papers I have read do some measurement and include a graphic which looks like: This graphic identifies how the ...
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21 views

### Possible Modification to Contour Method for Residual Stress Measurement

I've been studying the contour method for measuring residual stress. See https://www.lanl.gov/contour/ if you are not familiar. In the contour method, a single cut is made all the way through the ...
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1 vote
95 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 (...
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52 views

### Using Strain Tensors to Recover Stress Tensors

Disclaimer: I am very new to the field of mechanics, my background is in electrical engineering. I apologize in advance if anything is horribly wrong. My references are: "First Course in FEM, 4th ...
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1 vote
88 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 ...
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1 vote
264 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-...
138 views

### Units of measurement for structural analysis

FEA engine I'm using CCX finite elements analysis engine along with its pre- and post-processor CGX: http://www.dhondt.de/index.html https://github.com/calculix Example I'm looking at one example here ...
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I have a eigenfrequency simulation $M * \ddot{\vec{x}} + K * \vec{x} = \vec{0}$ and want to add point masses to certain nodes. The only example I have is a 1D matrix where all of the mass at node 1 ...
$s=R\tilde{s}$ 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 ...