# Questions tagged [finite-element-method]

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### How to derive Equivalent Static Load for irregular structure modeled with FEM?

Building codes such as the Uniform Building Code (UBC) or International Building Code (IBC) require the determination of Equivalent Static Lateral Forces in order to compute $P-\Delta$ effect and to ...
75 views

### Modeling the structure vs FEM

When you model the structure to be analyzed with a structural analysis program, indicating the beam elements, shell elements, nodes, rigid links etc... The analysis is still called Finite Element ...
638 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 ...
1k views

### How do I use FEM to derive the torsional constant of an arbitrary shape?

In this question I ask about how to perform a first-principle derivation of the torsional constant of a section. It appears that there is no such analytical derivation for torsional constant, so my ...
3k views

### Modeling Transient Heat Transfer between two 1-D materials

I have been working on creating a 1-D model of a material with a layer of heat resistant material stuck to it. For this I have been trying to use the implicit finite-differential method. The equations ...
2k views

### What amplitude is used for a finite element modal analysis excitation?

In a typical finite elements analysis package, a modal analysis gives the N first natural modes, and it is possible to get the equivalent stress and total deformations for each of these frequencies. ...
475 views

### FEA: What boundary conditions am I missing?

I'm working on a 2D-model (in the xy-plane) in NASTRAN and am getting convergence problems. The main cause of these convergence problems is a "high or negative matrix factor diagonal ratio." I've ...
406 views

### Stiffness Method FEM - Slender Members

If a member is very slender then its length will be large compared to its cross-sectional area. I've heard and read that slender members can potentially cause the stiffness matrix of a beam/frame ...
184 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 ...
1 vote
761 views

### Rayleigh-Ritz method, calculating slope of beam?

For a simply supported beam with a UDL if the deflection is assumed to be: $$V=a+bx+cx^2+dx^3$$ What is the formula for calculating the slope? I thought it would be: $$θ=dV/dx$$ However, working ...
1 vote
1k 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 ...