Learning Forum

[Anirudh Thantry]

I have created a 3D wing with its half span as a parameter in Design modeler. Now i want to apply pressure load with elliptical distribution on the bottom surface of the wing. I am not much familiar with APDL scripting, so can somebody help me with this... 

[Bill Bulat]

The APDL commands below are from an input file that defines an elliptical pressure patch that acts on the top face of a block and is then incrementally relocated along the x direction. Try copying them into a text file, then read that text file into MAPDL with the /INPUT command. I hope this helps you get started. Mind you, it looks like I created this back in 2017 and I haven't tested it to see if it still works, but my hunch is that it does.

Best,

Bill

 

 

finish

/clear

 

/sys,del file*.png

 

/vup,1,z ! VIEW SETTINGS. SPECIFIES GLOBAL CARTESIAN

! COORDINATE SYSTEM REFERENCE ORIENTATION.

! THIRD FIELD DEFINES Z VERTICAL UPWARD,

! Y HORIZONAL TO THE RIGHT, X OUT OF THE SCREEN

! YOU SHOULD USE A VIEW OTHER THAN THE /VIEW

! DEFAULT OF (0,0,1).

/view,1,1,3,1 ! DEFINES VIEWING DIRECTION FOR THE DISPLAY

/vscale,1,2.5 ! SCALES THE LENGTH OF DISPLAYED VECTORS

 

C***************

C*** PARAMETERS

C***************

 

r_ellipse=1 ! ELLIPTICAL BOUNDARY (MAJOR) RADIUS 101717 

!r_ellipse=0.4 ! ELLIPTICAL BOUNDARY (MAJOR) RADIUS 102017

 

a=1.5 ! BLOCK EDGE LENGTH

t=0.2 ! BLOCK THICKNESS

 

ratio=0.5 ! ELLIPTICAL RATIO OF MINOR & MAJOR DIAMETERS 101717

!ratio=0.75 ! ELLIPTICAL RATIO OF MINOR & MAJOR DIAMETERS 102017

 

esz=a/25 ! MESH SIZE 101717 (RESULTED IN 392 CONTACT ELEMENTS)

!esz=a/37 ! MESH SIZE 102017 (RESULTED IN 200 CONTACT ELEMENTS?)

 

pmax=100 ! MAX PRESSURE AT MIDDLE OF ELLIPTICAL CONTACT PATCH 101717

!pmax=40000 ! MAX PRESSURE AT MIDDLE OF ELLIPTICAL CONTACT PATCH 102017

 

!*dim,ellip_coor_num,array,392,2,1 ! DIMENSION ARRAY TO CHECK COORDINATES

! AND ELEMENT NUMBERS 101717

 

 

C**********

C*** MODEL

C**********

/prep7

 

wpcsys,-1,0 ! DEFINES WORKING PLANE LOCATION AND ORIENTATION

! BASED ON AN EXISTING COORDINATE SYSTEM.IF 2ND FIELD

! (WINDOW NUMBER) IS NEGATIVE, THE VIEWING DIRECTION 

! WILL NOT BE MODIFIED. 3RD FIELD IS COORDINATE SYSTEM NUMBER.

 

cswpla,11,1,ratio ! DEFINES / CREATES A LOCAL ELLIPTICAL COORDINATE  

! SYSTEM AT THE ORIGIN OF THE WORKING PLANE.

 

blocK,-a,a,-a,a,,-t ! CREATES BLOCK VOLUME BASED ON WORKING PLANE COORDINATES.

 

et,1,185 ! MESH IT WITH SOME ELEMENTS

esize,esz

vmesh,all ! GENERATED NODES AND VOLUME ELEMENTS W/I VOLUMES.

 

et,2,154 ! CREATE SURFACE EFFECT ELEMENTS ON ENTIRE z=0 SURFACE

nsel,s,loc,z

type,2

esurf

 

alls

/shr,0.05 ! "SHRINK" ELEMENTS SLIGHTLY TO SEE SURF154s

/ann,dele

/tla,-0.25,0.90,Plate with SURF154 on Entire Surface

eplot ! PLOT ELEMENTS TO CHECK

/sho,png $eplo $/sho,close $/wait,1.5 ! HARD COPY OF SAME (IMAGE FILE)

/shr ! TURN OFF SHRINK

 

/wait,2

 

 

C*******************************************************************

C*** CREATE MACRO TO DEFINE ELLIPTICAL LOAD @ X LOCATION (ARG1)

C*** MACRO NAME: mvng_elptcl_prs,mac

C*** ARGUMENTS:

C*** ARG1: X COORDINATE OF CENTER OF ELLIPTICAL PRESSURE DISTRIBUTION

C*******************************************************************

*cre,mvng_elptcl_prs,mac

 

wpcs,-1,0 ! WP @ GLOBAL ORIGIN

wpof,arg1 ! OFFSET WP ALONG ITS X AXIS (SPECIFIED BY ARGUMENT ARG1)

cswp,11,1,ratio ! DEFINE ELLIPTICAL COORDINATE SYSTEM @ WP ORIGIN

 

esel,s,ename,,154 ! SELECT SURFACE EFFECT ELEMENTS

nsle ! AND THEIR NODES

sfed,all,,pres ! DELETE PREEXISTING PRESSURE LOADS IF ANY

nsel,r,loc,x,0,r_ellipse ! RESELECT NODES WITHIN ELLIPTICAL BOUNDARY

esln,r,1 ! RESELECT SURF154s HAVING ALL THEIR NODES SELECTED

 

*get,nelems,elem,,count ! nelems = # OF SELECTED SURF154 ELEMENTS

elm=0 ! INITIALIZE ELEMENT NUMBER

*do,i,1,nelems ! LOOP OVER ELEMENTS

 elm=elnext(elm) ! elm = NEXT HIGHEST ELEMENT NUMBER ABOVE WHAT elm WAS PREVIOUSLY

 *get,r_csys11,elem,elm,cent,x ! GET ELEMENT elm's "ELLIPTICAL" COORDINATE

 sfe,elm,,pres,,pmax*(1-(r_csys11/r_ellipse)**2) ! APPLY PRESSURE TO ELEMENT elm

*enddo ! END DO LOOP

 

alls ! SELECT ENTIRE MODEL BEFORE PROCEEDING

 

*end ! END MACRO CREATION

 

/psf,pres,,2 ! SHOW PRESSURES AS ARROWS

 

 

*do,j,0,0.4,0.1 ! LOOP OVER X COORDINATE OF ELLIPTICAL PRESSURE DISTRIBUTION

 /ann,dele ! NEW ANIMATION FOR UPCOMING PLOT

 /tla,-0.25,0.90,elliptical pressure load centered at x = %j%

 mvng_elptcl_prs,j ! INVOKE MACRO (LOOP VARIABLE j PASSED TO MACRO TO LOCATE ELLIPTICAL PRESSURE DISTRIBUTION)

 eplo ! PLOT ELEMENTS w/PRESSURE ARROWS SHOWN

 /sho,png $eplo $/sho,close $/wait,1.5 ! HARD COPY OF SAME (IMAGE FILE)

*enddo ! END DO LOOP