Guest Lecture series - University of Canterbury ENME 302 - 30 September 2016 - Real World Boundary Conditions

Students of the Computational Mechanics course (ENME302) at Canterbury University received a Guest Lecture from Greg Morehouse. The topic was on Real World Boundary Conditions (BCs, Restraints, or Fixtures) in Finite Element Analysis (FEA). Boundary Conditions are one of the most difficult and misused features in FEA. The students appreciated the practical application that Greg brought to their theoretical Computational Mechanics studies.
If you would like to know more about how to have confidence in verifying your simulation results checkout our Tip & Trick, 3-2-1 Jig Theory applied to FEA

In this video snip Greg discusses the difference Craftsmanship can have in CAE (Computer Aided Engineering), specifically highlighting the difference between a Journeyman’s mindset and that of a Craftsman. Greg highlights that in any computer endeavor, it’s always the connection between the keyboard and the seat that makes sure GIGO (Garbage In – Garbage Out) doesn’t apply. Accurate use of FEA (Finite Element Analysis) requires rigour and competence, and it’s passion that makes the difference!

In this video snip Greg takes the opportunity to highlight how even in a seemly simple inbuilt “C” Channel analysis, the assumption of fixity should be questioned. In simple language he discusses the implications of Tx, Ty, Tz, Rx, Ry, Rz Boundary Conditions (BCs, Restraints or Fixtures) common to FEA in the real world, and introduces the concept of sometimes letting the structure take it’s natural shape to develop worst case stresses.

In this video snip Greg explains how 3-2-1 Jig Theory he learned in Boeing helps analysts develop free (unrestrained or natural) deflected shapes in FEMs (Finite Element Models). He uses the example of a simply supported beam and the expectation of a happy (smiley) deflected shape to understand why minimally restrained models often impose the worst case (highest) stress condition and so are at least conservative. He also highlights how important it is to have an expectation of the deflected shape you’re going to see, and stresses somewhere in the model, before running an FEA. He then highlights how difficult it can be in most CADs free (express) FEA add-ons to get even marginally accurate Boundary Conditions (BCs, Restraints or Fixtures).

In this video snip we discuss how Murphy’s Law suggests that if something can happen, it will. And if it does, we want our analyses to have been done on the basis of Worst Case, both in loadings and boundary conditions (BCs, Restraints or Fixtures). Since we can’t always get our boundary conditions accurate enough, remembering that Saint-Venant’s Principle applies can often help us swap loads and boundary conditions to get accuracy where we need it. Also, using 3-2-1 boundary conditions allows us to verify our models simply and quickly. Enjoy!

In this video snip Greg goes into his personal journey and discusses the importance of not just IQ (Intelligence Quotient), but EQ (Emotional Quotient) for engineers. It highlights the best place to improve ourselves is in our personal development. Greg highlights that EQ is about connecting with people. He mentions that through things like the Landmark Forum, the More To Life Weekends and Eckhart Tolle’s books and Nonviolent Communication (NVC) we can enhance our connection with others. And bring our passions to life!