Code books contain equations to design simple vessel shapes like cylindrical shells. What about shapes that are not found in code books? What about standard shapes used in arrangements or sizes not covered by the rules? This is the job for Finite Element Analysis (FEA).
A solid model is created. The model is split into small pyramids or cubes – a mesh of simple shapes that can be calculated by the laws of physics. Loads are applied to the mesh and displacements are calculated. Displacements are converted into stresses and both can be seen. Code rules separate areas of the model that are acceptable from those that are overstressed, and if required, the solid model is modified, and the process repeated until successful.
FEA can be used for much more. Wind and seismic loads can be input. Computational Fluid Dynamics (CFD) can determine shell temperature distributions which are used to calculate thermal displacement and stresses. Stresses are used to calculate the permissible cycle life (fatigue life).
The use of FEA is increasing. Users see the value in knowing the code permitted cycle life of their vessel. Designers can use irregular shapes more appropriate to their process needs. Inspectors are insisting on FEA for items that code rules do not do well – see the obround nozzle article below.
Introduction to FEA
If you are new to FEA we suggest starting with these pictorial guides.
FEA Samples and Articles
These are our most read FEA samples and articles. More can be found in the FEA blogs below.
FEA Blogs
More samples and articles, validation of our software and methods by comparison with published articles and FEA techniques.