Undamped Modal --- --- No ( 1 ) --- ---
Yes Yes Yes ( 1 ) Yes Yes
Mode Superposition
Harmonic
Mode Superposition Yes Yes Yes ( 1 ) Yes ---
Transient
Spectrum
SPRS,MPRS Yes Yes Yes ( 1 ) Yes ---
PSD Yes Yes Yes ( 1 ) Yes ---
DDAM Yes ( 3 ) Yes ( 3 ) Yes ( 3 ) Yes ( 3 ) Yes ( 3 )
- MP,DMPR specifies an effective material damping ratio. Specify it in the modal analysis (and expand the
modes,MXPAND,,,,YES) for use in subsequent spectrum and mode-superposition analyses. - The material dependent damping (MP,DMPR) and the mode dependent damping (MDAMP) cannot be
cumulated. Use only one method. - In DDAM analyses, damping input is not used when calculating mode coefficients; however, damping
may be used in the mode-combination procedure. Refer to Combination of Modes in the Mechanical
APDL Theory Reference for more information.
Table 1.3: Damping for Damped Modal and QRDAMP Mode Superposition Analyses
Damping Ratio Structural Damping
Element
Damping
( 1 )
Rayleigh Damping
Material
Depend-
ent
Global
Mode De-
Global pendent
Material
Depend-
ent
Global
DMPRAT MDAMP DMPSTR MP,DMPR
COM-
BIN14,
MP,BETD
and
MP,ALPD
ALPHAD
and
BETAD
MAT-
RIX27, ...
Yes Yes Yes --- --- Yes ( 3 ) Yes ( 3 )
Damped
Modal
(DAMP or
QRDAMP)
Yes ( 2 ) Yes ( 2 ) Yes Yes Yes Yes Yes
QRDAMP
Mode Su-
perposi-
tion Har-
monic
Yes ( 2 ) Yes ( 2 ) Yes Yes Yes --- ---
QRDAMP
Mode Su-
perposi-
tion Tran-
sient
- Includes superelement damping matrix
- ALPHAD,BETAD,MP,ALPD, and MP,BETD damping must be applied in the QR Damped modal analysis
portion of the mode-superposition analysis.
Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information
Overview of Structural Analyses