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--- doc:user:conditions:dead_loads [2014/10/07 10:31] – joris
+++ doc:user:conditions:dead_loads [2016/03/30 15:23] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
-====== Dead loads ======
+====== Prescribed Nodal "Dead" Loads ======
+ {{:doc:user:ico-advanced.png?40|Advanced}}{{:doc:user:ico-danger.png?40|Danger!}}
+Dead loads are forces that are directly prescribed at the nodes of the mesh. The amplitude and direction of such forces is known a priori. In particular it is independent from the deformation of the underlying material. Such forces also strongly depend on the chosen mesh desnity. Changing the mesh usually requires a complete redefinition of these forces.
-Dead loads are not which are applied on nodes, but whose amplitude and direction will not change during the computation.
+<note important>As a consequence, it is usually a bad idea to define nodal "dead" loads in a model. To model realistic loads (pressure and shear) which depend on the deformed configuration and do not depend on the mesh density, use [[doc:user:elements:boundaries:pressure_shear]].</note>
-To model a load which will always remain perpendicular to the deformed configuration, use [[doc:user:elements:boundaries:pressure_shear]].
+Anyway, the command used for the definition of "dead loads is the same as [[doc:user:conditions:displacements]] except that [[doc:user:general:locks|Field1D]] refers to a force instead of a displacement.
-__Careful!__ The specified value is applied on each node. Therefore, this force is not a resultant force. The resultant force is equal to the specified value times the number of nodes (so it is mesh dependent). This is another reason to use traction elements instead of dead loads.
-{{ doc:user:cha.gif |doc:user:cha.gif}}
-The command is the same as [[doc:user:conditions:displacements]] except that [[doc:user:general:locks|Lock]] is a force ''Lock'' (''TX,GF1'' for a force along ''x'', ...).