Introduction to nodes
The term "node" is a common finite element method term. However, when talking about SCIA Engineer program, we have to make a strict definition of what the word "node" means in the context of this software.
First of all, we have to distinguish between a standard finite element node and an ESA node. The two node types have something in common, but there are also some differences.
FE node
A standard finite element node will be always referred to as an "FE node". Normally, the user will not encounter this type of node when creating a model of a structure. The FE nodes must be dealt with just before the calculation of the project, and usually only in special cases. For common projects, the user can rely totally on the automatic finite element mesh generator integrated in the SCIA Engineer program.
Node
The word "node" will be used to talk about ESA nodes – i.e. about nodes (or points, if you prefer) that the user deals with.
A node is the simplest entity applied in SCIA Engineer program. A node is the basic element. The nodes define other entity types. For example, a 1D member is defined primarily by its two end-points that are nothing else but two nodes.
Each node has got some properties including:
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position in modelling space (i.e. co-ordinates),
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nodal co-ordinate system (used to define the direction of direction-related properties such as degrees of freedom).
Each node may belong to just one 1D member or to as many 1D members as required. If a node belongs to several 1D members, the 1D members are mutually connected in such a node and internal forces from one 1D member are transferred into the other 1D members. If required, special boundary conditions can be defined for the connection and thus only some of the internal forces (e.g. only bending moments or shear forces) may be transferred into the adjacent entities.
What the node and FE node have in common is that both are a proper finite element node. That means that the finite element mesh generator will ALWAYS place an FE node into an ESA node. On the other hand, the generator may add some more FE nodes in between the user-defined ESA nodes, in order to ensure that the finite element mesh corresponds with the required fineness.
There are several types of nodes depending on their "relation" to the 1D member they are part of.