By Frank Faulstich, Dlubal Engineering Software
Concentrated loads are frequently appearing on surfaces, but their application may cause problems. Each concentrated load, when introduced into a FE node, creates a singularity. This means that stresses in the location where loading is introduced depend on the FE mesh size. The finer the mesh, the higher the stress, which is absolutely unrealistic.
In reality, we can imagine that a load would never be introduced by an endlessly pointed needle. A typical example for concentrated loads are wheel loads where each wheel has a certain contact area. Thus, this load represents basically a small surface load.
We can solve the problem of singularities by modeling the location for load introduction as close as possible to reality. We are able to convert the concentrated load into an area load. The manual conversion, however, is time-consuming and error-prone. RFEM offers us a tool which facilitates this kind of work considerably. We right-click a (free) concentrated load to open the context menu where we select “Convert to Area Load”. A dialog box opens helping us to convert the load into a surface load.