Electromagnetic Loads

To specify a concentrated electric charge, specify the node or node set and the magnitude of the 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.

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.

In the direct-solution steady-state dynamics procedure, electric charges are given in terms of their real and imaginary components.

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.

To define concentrated currents, specify the node or node set and the magnitude of the current.

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.

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.

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.

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.

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.

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.