ProductsAbaqus/StandardAbaqus/ExplicitAbaqus/CAE Concentrated loadsIn Abaqus/Standard and Abaqus/Explicit analyses concentrated forces or moments can be applied at any nodal degree of freedom. You should not apply a moment load at the origin of a cylindrical coordinate system; doing so would make the radial and tangential loads indeterminate. Input File Usage CLOAD node number or node set, degree of freedom, magnitude Abaqus/CAE Usage Load module: Create Load: choose Mechanical for the Category and Concentrated force, Moment, or Generalized plane strain for the Types for Selected Step Specifying concentrated follower forcesYou can specify that the direction of a concentrated force should rotate with the node to which it is applied. This specification should be used only in large-displacement analysis and can be used only at nodes with active rotational degrees of freedom (such as the nodes of beam and shell elements or, in Abaqus/Explicit, tie nodes on a rigid body), excluding the reference node of generalized plane strain elements. If you specify follower forces, the components of the concentrated force must be specified with respect to the reference configuration. Follower loads lead to an unsymmetric contribution to the stiffness matrix that is generally referred to as the load stiffness. Some issues associated with the load stiffness contribution are discussed in Improving the rate of convergence in large-displacement implicit analysis. Input File Usage CLOAD, FOLLOWER Abaqus/CAE Usage Load module: Create Load: choose Mechanical for the Category and Concentrated force or Moment for the Types for Selected Step: Follow nodal rotation Defining the values of concentrated nodal force from a user-specified fileYou can define nodal force using nodal force output from a particular step and increment in the output database (.odb) file of a previous Abaqus analysis. The part (.prt) file from the original analysis is also required when reading data from the output database file. In this case both the previous model and the current model must be defined consistently, including node numbering, which must be the same in both models. If the models are defined in terms of an assembly of part instances, part instance naming must be the same. Input File Usage CLOAD, FILE=file, STEP=step, INC=inc Abaqus/CAE Usage Defining the values of concentrated nodal force from a user-specified file is not supported in Abaqus/CAE. Defining time-dependent concentrated loadsThe prescribed magnitude of a concentrated load can vary with time during a step according to an amplitude definition, as described in About Prescribed Conditions. If different variations are needed for different loads, each load can refer to its own amplitude. Modifying concentrated loadsConcentrated loads can be added, modified, or removed as described in About loads. Improving the rate of convergence in large-displacement implicit analysisWhen concentrated follower forces are specified in a geometrically nonlinear static and dynamic analysis, the unsymmetric matrix storage and solution scheme should normally be used. See Defining an analysis for more information on the unsymmetric matrix storage and solution scheme. |