Nonlinear supports in FEA: Gap Elements (NX Nastran) [Q&A #2]

By | September 12th, 2017|FEA: Intermediate, • Boundary Conditions, • Contact, FEA Topics:, Q&A, FEMAP|

Recently I got a great question from Ardalan (thanks for writing mate!) about defining nonlinear supports in FEA. I think he does a better job of defining the problem: First how to constraint an entity with in tolerance rather than completely fixing it? i.e. how to define a certain range of motion for an entity [...]

Buckling length in sway and non-sway structures

By | August 31st, 2017|• Structural Steel, • Stability, FEA: Intermediate, • Linear Buckling, FEA Topics:, Structural Design Topics:|

One of the few difficult things about buckling lengths is, that you need to know if your structure is a "sway" structure or a "non-sway" structure. Commonly the simple check is made with displacements, but unfortunately, it may lead to serious mistakes! Why should you care about sway and non-sway system Firstly, I want to [...]

Changing active forces for enforced deformations and vice versa

By | May 23rd, 2017|FEA: Basics, FEA: Intermediate, • Boundary Conditions, FEA Topics:|

I have seen many mistakes where people wrongly changed enforced deformations with active forces. In some cases, this is a simple task, which gives beginners the feeling that they can always do it easily. This, in turn, leads to various mistakes in analysis. I think it is worth discussing this, to point out common mistakes [...]

Solve issues with nonlinear analysis convergence!

By | May 16th, 2017|• Nonlinear Analysis, FEA: Intermediate, FEA: Advanced, FEA Topics:|

Lately, I got several emails with questions about nonlinear analysis convergence. There are a lot of reasons why your analysis could not converge. One of them is a wrong loads/increment strategy which I call "steering". Take a look at what are the possible options and what are the positive/negative aspects of each approach. Steering have [...]

Materially nonlinear analysis – how does it work

By | April 3rd, 2017|• Nonlinear Analysis, FEA: Intermediate, FEA Topics:|

When people think about nonlinear analysis usually what first comes to mind is material nonlinearity. This is the most “visible” aspect of nonlinearity in calculations. I won’t dare to say that materially nonlinear analysis is the most important one (I think that there is not such thing), but without a doubt, this is an important [...]

Boundary conditions influence on static design – case study

By | March 20th, 2017|FEA: Intermediate, • Boundary Conditions, FEA Topics:, Case Studies, FEMAP|

Each day we do simplifications to boundary conditions just to reduce time spent on analysis. We are all aware, that structured support is crucial, but the actual influence of the proper boundary conditions is rarely examined. See yourself how drastic influence BC have on your design! I will discuss this using a project I just [...]

Design your silos with FEA – it pays!

By | February 28th, 2017|• Structural Steel, • Nonlinear Analysis, • Stability, FEA: Intermediate, • Post Processing, FEA Topics:, Case Studies, Structural Design Topics:, FEMAP|

Designing steel silos with analytical approach always yields very conservative results. Nonlinear Finite Element Method allow for great optimization of those structures (and other shell structures as well!). I will discuss this based on a silo I have recently designed. […]

Imperfections in buckling design

By | January 31st, 2017|• Nonlinear Analysis, • Stability, FEA: Intermediate, FEA: Advanced, FEA Topics:, Structural Design Topics:, FEMAP|

Using deformations from linear buckling as imperfections in nonlinear buckling case is the most common approach. I will use a simple example to prove that this is not always the best idea. Proper selection of imperfections is a very complicated process – I hope to shed some light on this matter. […]

Linear vs nonlinear buckling explained!

By | January 24th, 2017|• Linear Analysis, • Nonlinear Analysis, FEA: Intermediate, • Linear Buckling, FEA Topics:, FEMAP|

Choosing between linear buckling and nonlinear buckling in given case can be difficult. Both approaches have positive and negative aspects. I explain here what are the differences, and when to use each analysis. I promise not to use complicated mathematics, nor highly theoretical approach. Instead, I will use a simple example to easily describe differences. [...]

Nonlinear buckling explained simply

By | January 10th, 2017|• Nonlinear Analysis, • Stability, FEA: Intermediate, FEA Topics:, Structural Design Topics:, FEMAP|

Nonlinear buckling is a really interesting analysis. It gives you enormous possibilities, at only a few minutes worth of work. At the start, it might be frustrating to set it up (there is a learning curve involved), but in the end, it is a default engineering tool for me right now! Possibilities are limitless! [...]

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