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Mental model ~5 min · ~57 min remaining

From the physical problem to the script

The quantity table and the .mac describe the same beam: each command translates a modeling decision.

Physical model

The template represents a cantilever beam with the following characteristics:

MagnitudValueUnit
Length1,00m
height0,10m
Width0,05m
Elastic modulus210·10⁹Pa
Poisson’s ratio0,30
Total vertical force−1000N

The end x=0 is embedded and the load acts on the nodes of x=1 m. The geometry is deliberately simple: at M00 we want to learn how to execute and read the analysis, not solving a complicated geometry.

The same beam in the table and in the script

The table above fixes the physical problem. The APDL script translates each decision into commands. These are not separate topics: each row corresponds to a section of the .mac file.

  • BLOCK BLOCK,0,1.0,0,0.10,0,0.05
    • 0, 1.0 — limits in X (length 1,0 m).
    • 0, 0.10 — limits in Y (height 0,10 m).
    • 0, 0.05 — limits in Z (width 0,05 m).
    → the dimensions of the volume.
  • MP,EX,1,210E9
    MP,PRXY,1,0.30
    • EX,1,210E9 — elastic modulus of the material 1 (Pa).
    • PRXY,1,0.30 — Poisson coefficient of the material 1.
    → the elastic properties of steel.
  • D,ALL,ALL,0 on x=0 NSEL,S,LOC,X,0 D,ALL,ALL,0
    • NSEL,S,LOC,X,0 — select the nodes in the plane x=0.
    • D,ALL,ALL,0 — constrains all degrees of freedom in the current selection.
    → the fixed support at the left end.
  • F,ALL,FY,-1000/n_tip NSEL,S,LOC,X,1.0 *GET,n_tip,NODE,0,COUNT F,ALL,FY,-1000/n_tip
    • NSEL,S,LOC,X,1.0 — select the nodes on the free end.
    • *GET,n_tip,... — counts how many nodes are selected.
    • F,ALL,FY,-1000/n_tip — distributes −1000 N among those nodes in Y.
    → the total force distributed at the free end.

When reading the anatomy of the script, do not memorize single lines: locate which physical decision encodes each block. Hover your cursor (or focus) over ? to view the command and the meaning of each argument.

Quick check

What does /UNITS,SI actually do?