CIRCU94 Element Description

CIRCU94 is a circuit element for use in piezoelectric-circuit analyses. The element has two or three nodes to define the circuit component and one or two degrees of freedom to model the circuit response. The element may interface with the following piezoelectric elements:

CIRCU94 is applicable to full harmonic and transient analyses. For these types of analyses, you can also use CIRCU94 as a general circuit element. See CIRCU94 in the Mechanical APDL Theory Reference for more details about this element.

CIRCU94 Input Data

The geometry, node definition, and degree of freedom options are shown in Figure 94.1: CIRCU94 Circuit Options. Active nodes I and J define the resistor, inductor, capacitor and independent current source. They are connected to the electric circuit. Active nodes I and J and a passive node K define the independent voltage source. The passive node is not connected to the electric circuit. It is associated with the CURR degree of freedom (which represents electric charge for this element).

KEYOPT(1) settings and the corresponding real constants define the circuit components. Real constant input is dependent on the element circuit option used. A summary of the element input options is given in "CIRCU94 Input Summary". Real constants 15 (Graphical offset, GOFFST) and 16 (Element identification number, ID) are created for all components.

Figure 94.1: CIRCU94 Circuit Options

The independent current and voltage sources (KEYOPT(1) = 3 or 4) may be excited by constant load (transient) or constant amplitude load (harmonic), sinusoidal, pulse, exponential, or piecewise linear load functions as defined by KEYOPT(2); see Figure 94.2: Load Functions and Corresponding Real Constants for Independent Current and Voltage Sources.

The time-step size for a transient analysis is controlled by the DELTIM or NSUBST commands. The CIRCU94 element does not respond to automatic time stepping (AUTOTS command), but AUTOTS can be used as a mechanism for ramping the time step to its final value.

CIRCU94 is only compatible with elements having a VOLT DOF and an electric charge reaction solution. Electric charge reactions must all be positive or negative. KEYOPT(6) sets the electric charge reaction sign. See Element Compatibility in the Low-Frequency Electromagnetic Analysis Guide for more information.

CIRCU94 Input Summary

Nodes

I, J, K

Degrees of Freedom

VOLT, CURR (charge) (see Figure 94.1: CIRCU94 Circuit Options)

Real Constants

R, L, C, I, V

Dependent on KEYOPT(1) and KEYOPT(2) settings. See Table 94.1: CIRCU94 Real Constants for details.

In a full harmonic analysis (ANTYPE,HARMIC and HROPT,FULL), real constants R, L, and C can be defined as table parameters using the frequency as the primary variable (Var1 = FREQ on the *DIM command).

In a full transient analysis (ANTYPE,TRANS and TRNOPT,FULL), real constants R, L, and C can be defined as table parameters using time as the primary variable (Var1 = TIME on the *DIM command).

Material Properties

None

Surface Loads

None

Body Loads

See KEYOPT(2)

Special Features

This element works with the large deflection and stress stiffening capabilities of PLANE13, SOLID5, SOLID98, PLANE223, SOLID226, and SOLID227.

KEYOPT(1)

Circuit component type:

0 -- 

Resistor

1 -- 

Inductor

2 -- 

Capacitor

3 -- 

Independent Current Source

4 -- 

Independent Voltage Source

KEYOPT(2)

Body loads (only used for KEYOPT(1) = 3 and 4):

0 -- 

Constant load (transient) or constant amplitude load (harmonic)

1 -- 

Sinusoidal load

2 -- 

Pulse load

3 -- 

Exponential load

4 -- 

Piecewise Linear load

KEYOPT(6)

Electric charge reaction sign:

0 -- 

Negative

1 -- 

Positive

Table 94.1: CIRCU94 Real Constants

Circuit Component and Graphics Label	KEYOPT(1)	Real Constants
Resistor (R)	0	R1 = Resistance (RES)
Inductor (L)	1	R1 = Inductance (IND) R2 = Initial inductor current (ILO)
Capacitor (C)	2	R1 = Capacitance (CAP) R2 = Initial Capacitor Voltage (VCO)
Independent Current Source (I)	3	For KEYOPT(2) = 0: R1 = Amplitude (AMPL) R2 = Phase angle (PHAS) For KEYOPT(2) > 0, see Figure 94.2: Load Functions and Corresponding Real Constants for Independent Current and Voltage Sources.
Independent Voltage Source (V)	4	For KEYOPT(2) = 0: R1 = Amplitude (AMPL) R2 = Phase angle (PHAS) For KEYOPT(2) > 0, see Figure 94.2: Load Functions and Corresponding Real Constants for Independent Current and Voltage Sources.

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Note:  For all above Circuit options, the GOFFST and ID real constants (numbers 15 and 16) are created by the Circuit Builder automatically:

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Figure 94.2: Load Functions and Corresponding Real Constants for Independent Current and Voltage Sources

CIRCU94 Output Data

The element output for this element is dependent on the circuit option selected. Table 94.2: CIRCU94 Element Output Definitions summarizes the element output data.

The Element Output Definitions table uses the following notation:

A colon (:) in the Name column indicates that the item can be accessed by the Component Name method (ETABLE, ESOL). The O column indicates the availability of the items in the file jobname.out. The R column indicates the availability of the items in the results file.

In either the O or R columns, “Y” indicates that the item is always available, a letter or number refers to a table footnote that describes when the item is conditionally available, and “-” indicates that the item is not available.

Table 94.3: CIRCU94 Item and Sequence Numbers lists output available through the ETABLE command using the Sequence Number method. See The General Postprocessor (POST1) in the Basic Analysis Guide and The Item and Sequence Number Table in this reference for more information. The following notation is used in Table 94.3: CIRCU94 Item and Sequence Numbers:

CIRCU94 Assumptions and Restrictions

CIRCU94 Product Restrictions

There are no product-specific restrictions for this element.