Equilibrium Finite Elements for the Safe Limit Analysis of Plates

Presenter - Angus Ramsay
Authors - Angus Ramsay & Edward Maunder


NAFEMS Beyond FEA Seminar at the National Physical Laboratory, Teddington, UK, 14th May 2015.


Equilibrium finite elements (EFE) overcome an inherent weakness of conventional conforming finite elements by providing strong forms of equilibrium irrespective of mesh refinement and thereby closing a significant opportunity for potentially costly FE malpractice. In predicting the plastic collapse of a structure conventional FE methods are slow (incremental analysis), awkward (many parameters to set) and produce collapse loads that with unconverged models may be considerably greater than the true value. In contrast, and by virtue of the lower-bound plasticity theorem, EFE provides predictions that are guaranteed to be less than the true value, i.e. safe approximations. This abstract presents some results from the EFE software tool and compares them with those produced by conventional conforming elements.

Additional Resources

Article - What is Equilibrium Finite Element Analysis?, NAFEMS Benchmark Magazine, January 2017.

Beyond FEA Presentation
Beyond FEA Extended Abstract