The types of
electromagnetic loads available depend on the analysis being performed, as described in the
sections below. See About Loads for general information that applies
to all types of loading.
The prescribed magnitude of a concentrated or a distributed electromagnetic
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 definition.
In a time-harmonic eddy current analysis all loads are assumed to be
time-harmonic.
Modifying Electromagnetic Loads
Concentrated or distributed electromagnetic loads can be added, modified,
or removed as described in
About Loads.
Prescribing Electromagnetic Loads for Piezoelectric Analyses
In a piezoelectric analysis a concentrated electric charge can be prescribed
at nodes, a distributed electric surface charge can be defined on element faces
and surfaces, and a distributed electric body charge can be defined on
elements.
Specifying Concentrated Electric Charge
To specify a concentrated electric charge, specify the node or node set and
the magnitude of the charge.
Specifying Element-Based Distributed Electric Charge
You can specify a distributed surface charge (on element faces) or a
distributed body charge (charge per unit volume). For an element-based surface
charge you must identify the face of the element upon which the charge is
prescribed in the charge label. The distributed charge types available depend
on the element type.
About the Element Library
lists the distributed charges that are available for particular elements.
Specifying Surface-Based Distributed Electric Charge
When you specify a distributed electric charge on a surface, the
element-based surface (see
Element-Based Surface Definition)
contains the element and face information. You must specify the surface name,
the electric charge label, and the electric charge magnitude.
Specifying Electric Charge in Direct-Solution Steady-State Dynamics Analysis
In the direct-solution steady-state dynamics procedure, electric charges are
given in terms of their real and imaginary components.
Loading in Mode-Based and Subspace-Based Procedures
Electrical charge loads should be used only in conjunction with residual
modes in the eigenvalue extraction step, due to the “massless” mode effect.
Since the electrical potential degrees of freedom do not have any associated
mass, these degrees of freedom are essentially eliminated (similar to Guyan
reduction or mass condensation) during the eigenvalue extraction. The residual
modes represent the static response corresponding to the electrical charge
loads, which will adequately represent the potential degree of freedom in the
eigenspace.
Prescribing Electromagnetic Loads for Coupled Thermal-Electrical and Fully Coupled Thermal-Electrical-Structural Analyses
In a coupled thermal-electrical analysis and fully coupled
thermal-electrical-structural analysis a concentrated current can be prescribed
at nodes, distributed current densities can be defined on element faces and
surfaces, and distributed body currents can be defined on elements.
Specifying Concentrated Current Density
To define concentrated currents, specify the node or node set and the
magnitude of the current.
Specifying Element-Based Distributed Current Density
You can specify distributed surface current densities (on element faces) or
distributed body current densities (current per unit volume). For element-based
surface current densities you must identify the face of the element upon which
the current is prescribed in the current label. The distributed current types
available depend on the element type.
About the Element Library
lists the distributed current densities that are available for particular
elements.
Specifying Surface-Based Distributed Current Densities
When you specify distributed current densities on a surface, the
element-based surface (see
Element-Based Surface Definition)
contains the element and face information. You must specify the surface name,
the current density label, and the current density magnitude.
Prescribing Electromagnetic Loads for Eddy Current and/or Magnetostatic Analyses
In an eddy current analysis a distributed surface current density vector can
be defined on surfaces and a distributed volume current density vector can be
defined on elements.
Specifying Element-Based Distributed Current Density Vectors
When you define a distributed volume current density vector, you must
specify the element or element set, the current density vector label, the
magnitude of the current density vector, the vector components of the current
density, and an optional orientation name that defines the local coordinate
system in which the vector components are specified. By default, the vector
components of the current density are defined with respect to the global
directions.
The specified current density vector direction components are normalized by
Abaqus
and, thus, do not contribute to the magnitude of the load.
Specifying Surface-Based Distributed Current Density Vectors
When you specify distributed current density vectors on a surface, the
element-based surface (see
Element-Based Surface Definition)
contains the element and face information. You must specify the surface name,
the current density vector label, and the magnitude of the current density
vector, the vector components of the current density, and an optional
orientation name that defines the local coordinate system in which the surface
current density is specified. By default, the vector components of the current
density are defined with respect to the global directions.
The specified current density vector direction components are normalized by
Abaqus
and, thus, do not contribute to the magnitude of the load.
Defining Nonuniform Current Density Vectors in a User Subroutine
Nonuniform volume current density vectors can be defined with user
subroutine
UDECURRENT, and nonuniform surface current density vectors can be
defined with user subroutine
UDSECURRENT. If the magnitude and direction components are given, the
values are passed into the user subroutine.
Specifying Real and Imaginary Components of Current Density Vectors in a Time-Harmonic Eddy Current Analysis
In a time-harmonic eddy current analysis, current density vectors are given
in terms of their real (in-phase) and imaginary (out-of-phase) components.