ADDAM, AF, AA, AB, AC, AD, AMIN
Specifies the acceleration spectrum computation constants
for the analysis of shock resistance of shipboard structures.
AFDirection-dependent acceleration coefficient for elastic or elastic-plastic analysis option (default = 0).
AA, AB, AC, ADCoefficients for the DDAM acceleration spectrum equations. Default for these coefficients is zero.
AMINMinimum acceleration value. It defaults to 6g, where g is the acceleration due to gravity.
This command specifies acceleration coefficients to analyze shock resistance of shipboard equipment. These coefficients are used to compute mode coefficients according to the equations given in Dynamic Design Analysis Method in the Mechanical APDL Theory Reference. The form of these equations is based on the Naval NRL Dynamic Design Analysis Method. This command, along with the VDDAM and SED commands, is used with the spectrum (ANTYPE,SPECTR) analysis as a special purpose alternative to the SV, FREQ, and SVTYP commands.
In order to perform a DDAM spectrum analysis
using a units system other than BIN (default), you must specify the
units system complying with the mass and length units of the model
using the /UNITS command. Issue the /UNITS command before defining the shock spectrum computation constants
(ADDAM). The ADDAM command is
not supported with the user-defined unite system (Label = USER on /UNITS).
DDASPEC may alternatively be used to calculate spectrum coefficients.
This command is also valid in PREP7.