34.4.5 Electromagnetic loads
Products: Abaqus/Standard Abaqus/CAE
References
“Defining a concentrated current,” Section 16.9.25 of the Abaqus/CAE User's Guide
“Defining a surface current,” Section 16.9.26 of the Abaqus/CAE User's Guide
“Defining a body current,” Section 16.9.27 of the Abaqus/CAE User's Guide
“Defining a surface current density,” Section 16.9.28 of the Abaqus/CAE User's Guide
“Defining a body current density,” Section 16.9.29 of the Abaqus/CAE User's Guide
“Defining a concentrated charge,” Section 16.9.30 of the Abaqus/CAE User's Guide
“Defining a surface charge,” Section 16.9.31 of the Abaqus/CAE User's Guide
“Defining a body charge,” Section 16.9.32 of the Abaqus/CAE User's Guide
Overview
As outlined in “Prescribed conditions: overview,” Section 34.1.1, electromagnetic loads can be applied in “Piezoelectric analysis,” Section 6.7.2; “Coupled thermal-electrical analysis,” Section 6.7.3; “Fully coupled thermal-electrical-structural analysis,” Section 6.7.4; “Eddy current analysis,” Section 6.7.5; and “Magnetostatic analysis,” Section 6.7.6.
The types of electromagnetic loads available depend on the analysis being performed, as described in the sections below. See “Applying loads: overview,” Section 34.4.1, for general information that applies to all types of loading.
Defining time-dependent electromagnetic loads
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 “Prescribed conditions: overview,” Section 34.1.1. 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 “Applying loads: overview,” Section 34.4.1.
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.
| Input File Usage: | *CECHARGE node number or node set name, , charge magnitude |
| Abaqus/CAE Usage: | Load module: Create Load: choose Electrical/Magnetic for the Category and Concentrated charge for the Types for Selected Step; Magnitude: charge magnitude |
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. Part VI, “Elements,” lists the distributed charges that are available for particular elements.
| Input File Usage: | *DECHARGE element number or element set name, charge label, charge magnitude |
where charge label is ESn or EBF |
| Abaqus/CAE Usage: | Use the following input to define a distributed surface charge on element faces: |
Load module: Create Load: choose Electrical/Magnetic for the Category and Surface charge for the Types for Selected Step; Distribution: select an analytical field, Magnitude: charge magnitude Use the following input to define a body charge: Load module: Create Load: choose Electrical/Magnetic for the Category and Body charge for the Types for Selected Step |
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,” Section 2.3.2) contains the element and face information. You must specify the surface name, the electric charge label, and the electric charge magnitude.
| Input File Usage: | *DSECHARGE surface name, ES, charge magnitude |
| Abaqus/CAE Usage: | Load module: Create Load: choose Electrical/Magnetic for the Category and Surface charge for the Types for Selected Step; Distribution: Uniform, Magnitude: 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.
| Input File Usage: | Use the following options to define electric charges in direct-integration steady-state dynamics analysis: |
*CECHARGE, REAL or IMAGINARY (real or imaginary component) *DECHARGE, REAL or IMAGINARY *DSECHARGE, REAL or IMAGINARY |
| Abaqus/CAE Usage: | Load module: Create Load: choose Electrical/Magnetic for the Category and Concentrated charge, Surface charge, or Body charge for the Types for Selected Step; Magnitude: real component + imaginary component |
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.
| Input File Usage: | *CECURRENT node number or node set name, , current magnitude |
| Abaqus/CAE Usage: | Load module: Create Load: choose Electrical/Magnetic for the Category and Concentrated current for the Types for Selected Step; Magnitude: current magnitude |
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. Part VI, “Elements,” lists the distributed current densities that are available for particular elements.
| Input File Usage: | *DECURRENT element number or element set name, current density label, current density magnitude |
where current density label is CSn, CS1, CS2, or CBF |
| Abaqus/CAE Usage: | Use the following input to define a distributed surface current density on element faces: |
Load module: Create Load: choose Electrical/Magnetic for the Category and Surface current for the Types for Selected Step; Distribution: select an analytical field, Magnitude: current density magnitude Use the following input to define a body current density: Load module: Create Load: choose Electrical/Magnetic for the Category and Body current for the Types for Selected Step |
Specifying surface-based distributed current densities
When you specify distributed current densities on a surface, the element-based surface (see “Element-based surface definition,” Section 2.3.2) contains the element and face information. You must specify the surface name, the current density label, and the current density magnitude.
| Input File Usage: | *DSECURRENT surface name, CS, current density magnitude |
| Abaqus/CAE Usage: | Load module: Create Load: choose Electrical/Magnetic for the Category and Surface current for the Types for Selected Step: Distribution: Uniform, Magnitude: 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.
| Input File Usage: | *DECURRENT element number or element set name, CJ, current density vector magnitude, current density vector direction components, orientation name |
| Abaqus/CAE Usage: | Load module: Create Load: choose Electrical/Magnetic for the Category and Body current density for the Types for Selected Step; Distribution: Uniform |
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,” Section 2.3.2) 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.
| Input File Usage: | *DSECURRENT surface name, CK, current density vector magnitude, current density vector direction components, orientation name |
| Abaqus/CAE Usage: | Load module: Create Load: choose Electrical/Magnetic for the Category and Surface current density for the Types for Selected Step; Distribution: Uniform |
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.
| Input File Usage: | Use the following option to define nonuniform element-based current density vectors: |
*DECURRENT element number or element set name, CJNU, current density vector magnitude, current density vector direction components, orientation name Use the following option to define nonuniform surface-based current density vectors: *DSECURRENT surface name, CKNU, current density vector magnitude, current density vector direction components, orientation name |
| Abaqus/CAE Usage: | Use the following option to define nonuniform volume current density: |
Load module: Create Load: choose Electrical/Magnetic for the Category and Body current density for the Types for Selected Step; Distribution: User-defined Use the following option to define nonuniform surface current density: Load module: Create Load: choose Electrical/Magnetic for the Category and Surface current density for the Types for Selected Step; Distribution: User-defined |
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.
| Input File Usage: | Use the following options to define current density vectors: |
*DECURRENT, REAL or IMAGINARY *DSECURRENT, REAL or IMAGINARY |
| Abaqus/CAE Usage: | Load module: Create Load: choose Electrical/Magnetic for the Category and Body current density or Surface current density for the Types for Selected Step; real components + imaginary components |