Two-Way Radio User Manual

ManualsBrands3D Connexion ManualsTwo-Way RadioKeywords Reference Manual: Volume II Version 6.6

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MODAL DAMPING

analysis,” Section 6.3.11 of the ABAQUS Analysis User’s Manual). The value of the damping

constant, s, that m ultiplies the internal forces is entered on the data line .

Optional parameter:

DEFINITION

Set DEFINITION=MODE NUMBERS (default) to indicate that the damping values are given for

thespeciﬁedmodenumbers.

Set DEFINITION=FREQUENCY RANGE to indicate that the damping values are given for

the speciﬁed frequency ranges. Frequency ranges can be discontinuous.

If both the

MODAL DAMPING and

SELECT EIGENMODES options are used in the same

step, the DEFINIT ION parameter must be set equal to the same value in both options.

Data lines to deﬁne a fraction of critical damping by specifying mode numbers (MODAL=DIRECT

and DEFINITION=MODE NUMBERS):

First line:

1. Mode number of the lowest mode of a range.

2. Mode number of the highest mode of a range. (If this entry is left blank, it is assumed to be

the same as the previous entry so that values are being given for one mode only.)

3. Fraction of critical damping,

Repeat this data line as often as necessary to deﬁne modal damping for different modes.

Data lines to deﬁne Rayleigh damping by specifying mode numbers (RAYLEIGH and

DEFINITION=MODE NUMBERS):

First line:

1. Mode number of the lowest mode of a range.

2. Mode number of the highest mode of a range. (If this entry is left blank, it is assumed to be

the same as the previous entry so that values are being given for one mode only.)

3. Mass proportional damping,

4. Stiffness proportional damping,

Repeat this data line as often as necessary to deﬁne modal damping for different modes.

Data lines to deﬁne composite modal damping (MODAL=COMPOSITE):

First line:

1. Mode number of the lowest mode of a range.

2. Mode number of the highest mode of a range. (If this entry is left blank, it is assumed to be

the same as the previous entry so that values are being given for one mode only.)

Repeat this data line as often as necessary to deﬁne modal damping for different modes.

13.10–2

ABAQUS Version 6.1 Module:

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