ddaspec

Mapdl.ddaspec(keyref='', shptyp='', mountloc='', deftyp='', amin='', **kwargs)

APDL Command: DDASPEC

Specifies the shock spectrum computation constants for DDAM analysis.

Parameters:

keyref

Key for reference catalog:

1 - The spectrum computation constants are based on NRL-1396 (default). For more

information, see Dynamic Design Analysis Method in the Mechanical APDL Theory Reference

shptyp

Select the ship type:

SUBM - Submarine

SURF - Surface ship

mountloc

Select the mounting location:

HULL - Hull mounting location. These structures are mounted directly to basic hull

structures like frames, structural bulkheads below the water line, and shell plating above the water line.

DECK - Deck mounting location. These structures are mounted directly to decks, non-

structural bulkheads, or to structural bulkheads above the water line.

SHEL - Shell plating mounting location. These structures are mounted directly to shell

plating below the water line without intervening foundations.

deftyp

Select the deformation type:

ELAS - Elastic deformation (default)

PLAS - Elastic-plastic deformation

amin

Minimum acceleration value in inch/sec2. It defaults to 2316 inch/sec2 which equals 6g, where g is the acceleration due to gravity (g = 386 in/sec2).

Notes

The excitation direction is required to calculate the spectrum coefficients. Issue the SED command before issuing DDASPEC.

ADDAM and VDDAM may alternatively be used to calculate spectrum coefficients.

This command is also valid in PREP7.