# [Gmsh] How to generate 'plugin crack' for post processing

Xiaoxin Lu xiaoxin.lu at u-pem.fr
Thu Sep 29 17:44:56 CEST 2016

```Hello,

I am a PhD student using GMSH to generate crack faces. However, I could not find any example for this kind of post processing.
My .geo file is attached below, I put 'plugin crack' command inside but it did not work, I was wondering how to generate a post process file for this command.

best regards,
Xiaoxin
//start of the file
lc1 = 3;
lc2 = 3;

// We proceed by defining some elementary entities describing a cube:

Point(1) = {0,0,0,lc1};
Point(2) = {40,0,0,lc1};
Point(3) = {40,40,0,lc1};
Point(4) = {0,40,0,lc1};
Point(5) = {0,0,40,lc1};
Point(6) = {40,0,40,lc1};
Point(7) = {40,40,40,lc1};
Point(8) = {0,40,40,lc1};

Line(30)={1,2};
Line(31)={2,3};
Line(32)={3,4};
Line(33)={4,1};
Line(34)={5,6};
Line(35)={6,7};
Line(36)={7,8};
Line(37)={8,5};
Line(38)={1,5};
Line(39)={2,6};
Line(40)={3,7};
Line(41)={4,8};
Line Loop(42)={30,31,32,33};
Plane Surface(14)={42};
Line Loop(43)={-37,-36,-35,-34};
Plane Surface(16)={43};
Line Loop(44)={38,34,-39,-30};
Plane Surface(18)={44};
Line Loop(45)={-32,40,36,-41};
Plane Surface(20)={45};
Line Loop(46)={-33,41,37,-38};
Plane Surface(22)={46};
Line Loop(47)={39,35,-40,-31};
Plane Surface(24)={47};
vol1[]=Extrude{0,0,40}{Surface{14};};
Delete {Volume{vol1[1]};}
vol2[]=Extrude{0,40,0}{Surface{18};};
Delete {Volume{vol2[1]};}
vol3[]=Extrude{40,0,0}{Surface{22};};
Delete {Volume{vol3[1]};}
Physical Surface(1)={14};
Physical Surface(2)={vol1[0]};
Physical Surface(3)={18};
Physical Surface(4)={vol2[0]};
Physical Surface(5)={22};
Physical Surface(6)={vol3[0]};
Surface Loop(1)={14,vol2[0],vol3[0],18,22,vol1[0]};
Volume(1)={1};
Physical Volume(1)={1};

Point(5000)={1.645000e+01,7.466800e+00,5.890600e+00,lc2};
Point(5001)={1.728000e+01,2.112300e+01,1.204100e+01,lc2};
Point(5002)={2.823700e+01,1.636900e+01,2.111600e+01,lc2};
Point(5003)={2.740700e+01,2.713500e+00,1.496600e+01,lc2};
Line(5004)={5000,5001};
Line(5005)={5001,5002};
Line(5006)={5002,5003};
Line(5007)={5003,5000};
Line Loop(5008)={5004,5005,5006,5007};
Plane Surface(5009)={5008};
Physical Surface(11)={5009};
Surface{5009} In Volume{1};

Plugin(Crack).Dimension = 2 ;
Plugin(Crack).PhysicalGroup = 11 ;
Plugin(Crack).OpenBoundaryPhysicalGroup = 0 ;
Plugin(Crack).Run ;
//end of the file
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