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!ACCELERATION

Definition of acceleration boundary conditions

Parameters

TYPE = INITIAL (initial acceleration boundary condition)
     = TRANSIT (time-history acceleration boundary condition specified by AMPLITUDE: default)
GRPID = group ID
AMP  = time function name (specified by !AMPLITUDE)
       !AMPLITUDE defines the relationship between time t and coefficient f(t).
       The value obtained by multiplying Value below by coefficient f(t) is the prescribed value at that time
       (if not specified: the time-coefficient relationship is f(t) = 1.0).

** 2nd line and later **

(2nd line) NODE_ID, DOF_idS, DOF_idE, Value
Variable Attribute Description
NODE_ID I/C Node number or node group name
DOF_idS I Start number of constrained degree of freedom
DOF_idE I End number of constrained degree of freedom
Value R Prescribed value (default: 0)

Example

!ACCELERATION, TYPE=TRANSIT, AMP=AMP1
  1, 1, 3, 0.0
  ALL, 3, 3
  Note: The prescribed value is 0.0
!ACCELERATION, TYPE=INITIAL
  1, 3, 3, 1.0
  2, 3, 3, 1.0
  3, 3, 3, 1.0
  • Unlike displacement boundary conditions, acceleration boundary conditions cannot define multiple degrees of freedom collectively; therefore, DOF_idS and DOF_idE must be the same number.
  • When TYPE is INITIAL, AMP is ignored.
  • GRPID is used to activate acceleration boundary conditions on a step-by-step basis and is referenced from !STEP through its BOUNDARY line.