SimScale structural analysis uses exclusively solid 3D finite elements with a basic choice of either first order (4 node) or second order (10 node) tetrahedrals. Which should I chose
Some additional, less frequently used finite elements are also available in SimScale but will not be discussed in this article.
Second order elements capture the structural behaviour more accurately but are computationally intensive due to the increased number of nodes. Users should note that when discussing meshes in FEA the number of nodes not the number of cells is the defining feature. You can check the number of nodes in any of your generated meshes as shown below,
Generally mesh sizes over a few million nodes should be avoided and you should aim to achieve mesh independent results with the least number of nodes possible so as to minimise computational cost. Mesh independence means that if the mesh fineness is reduced the results do not change significantly.
As a rule of thumb, second order elements should always be used when possible in order to maximise accuracy. Unfortunately this is generally not the case for very large, complex geometries as the mesh size becomes too large with second order elements. For complex geometries first order elements will have to be used. This can significantly reduce the accuracy of your simulation particularly when thin parts are present that undergo bending. When using first order elements you will need at least 3 elements through the thickness of all parts in order to produce results that reflect realistic bending.