Guest Lecture - 7th October 2016


Students of the Computational Mechanics course (ENME302) at Canterbury University received a second lecture from Greg Morehouse.  The first snippets are an expansion of last week’s Boundary Conditions topic.  Then this week’s topic was on singularities in Finite Element Analysis (FEA).  One singularity which can occur is when stresses in sharp corners of models are theoretically infinite.  As a result, stresses won't converge as mesh is refined more and more.  Essentially it is mathematically equivalent to dividing by zero.  Knowing where and how these occur during simulation helps to interpret FEA results accurately.  The students appreciate the practical application that Greg brought to their theoretical studies.

Note the singularity video snippets aren’t up quite yet!

Greg also highlights again ways to not only be a better engineer, but a better employee, partner and person.

Enjoy the videos!

Symmetry as a boundary condition is one of the most powerful tools in an FE analysis toolbox.  In this introduction snippet Greg describes why Symmetry is so powerful, and some things to watch for while using it.

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Symmetry as a boundary condition is applied and used differently for different element types. In this video snippet Greg describes what the different element types are and how Symmetry might be used with each.

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Symmetrical Boundary Conditions provide a number of advantages to an FE analyst, including the fact that they allow the problem to accurately restrained quite easily.  But the greatest benefit comes in reducing run times, from overnight to the time it takes to get a cup of coffee in some cases!

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Most of the mechanical CAD packages offer a free version of their inbuilt Simulation (FE Analysis) softwares.  These Express versions are intentionally limited so in this video blog Greg highlights they are still quite valuable, and used with care and cunning can actually solve some complex analysis problems, free of charge!

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In this video snippet Greg describes how useful failure is, and how as we get better at something we don’t allow this powerful learning tool to help us anymore.  A great video for engineers to share with their boss about why trying something new is always a risk, but also can be amazingly good!

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In this video snippet Greg highlights some of the difficulties posed in creating a symmetrical boundary condition with the free (Express) versions of the simulation (FEA) softwares built in to most CAD packages these days.

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In this video snippet Greg highlights how to actual apply a boundary condition which mimics symmetry, a 90% Pareto Principle solution which is close enough.  He explains why it’s wrong due to Poison’s Ratio, and highlights how to interpret your results more accurately.  He also offers the link below to provide you with a worked example to better understand the challenges and how to get around them the Motovated Way!

Worked example of Simple Beam Analysis with Free (Express) FEA Software

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In this video snippet Greg highlights how easier problems are actually hard in FEA, so just stick with your math for the easy ones.  Reserve FEA for the hard problems!  Hand calculations are required to verify the FEA anyway, so never give up on the math.  MathCAD Prime makes this easy for engineers, and their free (Express) version is more powerful than the version Greg used as a subcontractor to Boeing to develop templates and process which were quick and robust.  The express (free) versions of analysis software available to engineers today is better than the best tools we had in the previous century.  But it’s still the connection between the keyboard and the seat that does the real thinking in analysis software, so recognise it’s in the work you do on yourself where the biggest gains will be achieved!

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