ABAQUS Volume II: I–Z - Manual (Page 147)

*MODAL DAMPING
Data lines to define structural damping by specifying mode numbers (STRUCTURAL 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. Damping factor, s.
Repeat this data line as often as necessary to define modal damping for different modes.
Data lines to define a fraction of critical damping by specifying frequency ranges
(MODAL=DIRECT and DEFINITION=FREQUENCY RANGE):
First line:
1. Frequency value (in cycles/time).
2. Fraction of critical damping, .
Repeat this data line as often as necessary to define modal damping for different frequencies. ABAQUS
will interpolate linearly between frequencies and keep the damping value constant and equal to the closest
specified value outside the frequency range.
Data lines to define Rayleigh damping by specifying frequency ranges (RAYLEIGH and
DEFINITION=FREQUENCY RANGE):
First line:
1. Frequency value (in cycles/time).
2. Mass proportional damping, .
3. Stiffness proportional damping, .
Repeat this data line as often as necessary to define modal damping for different frequencies. ABAQUS
will interpolate linearly between frequencies and keep the damping value constant and equal to the closest
specified value outside the frequency range.
Data lines to define structural damping by specifying frequency ranges (STRUCTURAL and
DEFINITION=FREQUENCY RANGE):
First line:
1. Frequency value (in cycles/time).
2. Damping factor, s.
Repeat this data line as often as necessary to define modal damping for different frequencies. ABAQUS
will interpolate linearly between frequencies and keep the damping value constant and equal to the closest
specified value outside the frequency range.
13.10–3
ABAQUS Version 6.1 Module: ID:
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