SDAMPING

Subcase Information Entry The SDAMPING command can be used to apply modal damping as a function of natural frequency in modal solutions.

Format

SDAMPING(type) = option

Definitions

Argument Options Description
type <STRUCTURE, FLUID> The referenced Bulk Data Entry is applied to:
STRUCTURE (Default)
Structural portion of the model.
FLUID
Fluid portion of the model.
option <SID>

No default
SID
Set identification of a TABDMP1 Bulk Data Entry.

Comments

  1. SDAMPING can only be used in modal transient, modal frequency response and modal complex eigenvalue analyses; and must reference a TABDMP1 Bulk Data Entry.
  2. Only one SDAMPING entry of each type can be defined for each subcase.
  3. If only one type of SDAMPING entry is defined (either SDAMPING(STRUCTURE) or SDAMPING(FLUID)), this definition will be used for both the structure and the fluid portion of the model.
  4. If present above the first subcase, it is applied to each modal frequency or modal transient subcase without an SDAMPING entry.
  5. To achieve identical displacements in Modal frequency response or Modal transient analyses when the SDAMPING Bulk Data Entry is used instead of PARAM,G, the steps described here can be followed:
    • The TYPE field in the TABDMP1 Bulk Data Entry should be set to CRIT. This TABDMP1 Bulk Data Entry is referenced by the SDAMPING Subcase Information Entry.
    • Set the damping value (field gi) in the TABDMP1 Bulk Data Entry equal to half of the value of PARAM,G (that is set the constant value to C / C 0 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qaiaac+ cacaWGdbWaaSbaaSqaaiaaicdaaeqaaaaa@391F@ ).
    • Set PARAM, KDAMP,-1