Example 7: Using Virtual Geometry

Virtual geometry operations allow you to change the parameters of a mesh without changing the original geometry. In this example, virtual geometry is used to remove unwanted small curves and create a volume suitable for sweeping. The function of creating compound curves is used, which combines small curves obtained by cutting a surface of small curvature. Then, to provide a sweep, the command of creating additional sections on the surface is used.

Fig. 1 - Geometric model

Proposed sections

Table 1. - Commands for preparing geometry for mesh construction according to the sweeping scheme.

Section view	Commands
	FIDESYS> webcut volume 1 sweep surface 2 vector 0 0 -1 through_all
	FIDESYS> webcut volume 3 sweep surface 108 vector 0 0 -1 through_all
	FIDESYS> webcut volume 3 sweep surface 13 vector 0 0 -1 through_all FIDESYS> webcut volume 3 sweep surface 28 vector 0 0 -1 through_all FIDESYS> webcut volume 3 sweep surface 74 vector 0 0 -1 through_all
	FIDESYS> webcut volume 3 with sheet extended from surface 197
	FIDESYS> webcut volume 8 with sheet extended from surface 224
	FIDESYS> webcut volume 11 10 12 9 with plane surface 28
	FIDESYS> webcut volume 3 with plane normal to curve 116 fraction 0.5
	FIDESYS> webcut volume 3 17 with plane normal to curve 835 close_to vertex 487
	FIDESYS> webcut volume 18 19 with sheet extended from surface 376
	FIDESYS> webcut volume 3 17 with sheet extended from surface 378
	FIDESYS> webcut volume 8 with sheet extended from surface 73 FIDESYS> webcut volume 8 with sheet extended from surface 72 FIDESYS> webcut volume 8 with sheet extended from surface 133 FIDESYS> webcut volume 8 with sheet extended from surface 71
	FIDESYS> webcut volume 8 with plane vertex 709 vertex 713 vertex 702
	FIDESYS> unite volume 36 45 FIDESYS> unite volume 37 43 FIDESYS> unite volume 35 44 FIDESYS> unite volume 39 42
	FIDESYS> webcut volume 29 with plane vertex 81 vertex 93 vertex 154
	FIDESYS> unite volume 33 36 50 11 FIDESYS> unite volume 10 49 37 31 FIDESYS> unite volume 12 52 35 34 FIDESYS> unite volume 9 51 39 32 FIDESYS> unite volume 9 22 FIDESYS> unite volume 12 23 FIDESYS> unite volume 20 33 FIDESYS> unite volume 21 10
	FIDESYS> webcut volume 12 with plane vertex 86 vertex 71 vertex 76 FIDESYS> webcut volume 53 with plane vertex 738 vertex 87 vertex 741 FIDESYS> webcut volume 12 with plane vertex 72 vertex 85 vertex 74 FIDESYS> webcut volume 55 with plane vertex 754 vertex 205 vertex 208 FIDESYS> webcut volume 12 sweep surface 731 along curve 1073 through_all FIDESYS> unite volume 53 57 56 FIDESYS> unite volume 54 12 55 FIDESYS> webcut volume 9 with plane vertex 99 vertex 101 vertex 103 FIDESYS> webcut volume 58 with plane vertex 769 vertex 98 vertex 772 FIDESYS> webcut volume 9 with plane vertex 106 vertex 104 vertex 100 FIDESYS> webcut volume 60 with plane vertex 781 vertex 201 vertex 198 FIDESYS> webcut volume 9 sweep surface 764 along curve 1078 through_all FIDESYS> unite volume 58 62 60 FIDESYS> unite volume 59 9 61 FIDESYS> webcut volume 20 with plane vertex 140 vertex 138 vertex 135 FIDESYS> webcut volume 63 with plane vertex 139 vertex 137 vertex 134 FIDESYS> webcut volume 20 with plane vertex 141 vertex 800 vertex 796 FIDESYS> webcut volume 64 with plane vertex 803 vertex 220 vertex 223 FIDESYS> webcut volume 63 sweep surface 803 along curve 1238 through_all FIDESYS> unite volume 20 67 66 FIDESYS> unite volume 65 63 64 FIDESYS> webcut volume 21 with plane vertex 165 vertex 163 vertex 160 FIDESYS> webcut volume 68 with plane vertex 164 vertex 162 vertex 159 FIDESYS> webcut volume 21 with plane vertex 825 vertex 169 vertex 822 FIDESYS> webcut volume 69 with plane vertex 830 vertex 216 vertex 213 FIDESYS> webcut volume 68 sweep surface 836 along curve 1069 through_all FIDESYS> unite volume 21 72 69 FIDESYS> unite volume 70 68 71 These commands make cuts on the 4 stiffeners, as shown in the figures. They are made for each rib. In doing so, small curves are created that will be removed later.
	FIDESYS> webcut volume 70 65 59 54 with plane surface 2
	FIDESYS> unite volume 1 76 75 73 74
	FIDESYS> unite volume 28 47 46 41 48 38 8 30 29 40
	FIDESYS> webcut volume 28 with plane surface 870 FIDESYS> webcut volume 28 77 with plane surface 871 FIDESYS> webcut volume 28 77 with plane surface 878 FIDESYS> webcut volume 28 77 with plane surface 879
	FIDESYS> webcut volume 1 81 2 82 with plane normal to curve 1849 fraction 0.5
	FIDESYS>webcut volume 19 18 with plane normal to curve 843 fraction 0.75
	FIDESYS> create curve vertex 1122 vertex 471 on surface 1134
	FIDESYS> webcut volume 19 sweep curve 2073 along curve 2042 through_all FIDESYS> webcut volume 18 with sheet extended from surface 1146 FIDESYS> webcut volume 18 with sheet extended from surface 1135
	FIDESYS> unite volume 91 92 FIDESYS> delete curve 2073
	FIDESYS> unite volume 89 18 FIDESYS> unite volume 88 19 FIDESYS> imprint all FIDESYS> merge all
	Combining small curves obtained by performing cuts into composite curves: FIDESYS> composite create curve 1456 1468 FIDESYS> composite create curve 1459 1467 FIDESYS> composite create curve 1499 1511 FIDESYS> composite create curve 1502 1510 FIDESYS> composite create curve 1371 1379 FIDESYS> composite create curve 1370 1381 FIDESYS> composite create curve 1423 1413 FIDESYS> composite create curve 1422 1414 FIDESYS> volume all scheme auto
	Creating sections of curves and surfaces using existing vertices: FIDESYS> partition create surface 1067 vertex 311 175 FIDESYS> partition create surface 1067 vertex 174 312 FIDESYS> partition create surface 1063 vertex 123 294 FIDESYS> partition create surface 1251 vertex 170 226 FIDESYS> partition create surface 1082 vertex 195 115 FIDESYS> partition create surface 1082 vertex 242 116 FIDESYS> partition create surface 1077 vertex 117 309 FIDESYS> partition create surface 1255 vertex 118 310
	In this case, the order of partitioning into elements is important. Since a constant number of intervals is set for the partitioned volume, you should check their equality on adjacent volumes. Usually the mesh generation algorithm performs such a check, but sometimes it is useful to split the volumes in a certain order. The order of splitting can have a significant impact on the quality of the generated mesh. FIDESYS> reset volume all FIDESYS> volume all scheme auto FIDESYS> volume 81 scheme sweep source surface 979 target surface 1061 rotate off FIDESYS> volume 81 sweep smooth auto FIDESYS> volume 85 scheme sweep source surface 1061 target surface 889 rotate off FIDESYS> volume 85 sweep smooth auto FIDESYS> volume all size 0.1 FIDESYS> curve 2125 2122 interval 12 FIDESYS> mesh vol 5 6 7 13 14 15 16 (COLORED GREEN) FIDESYS> mesh Volume 85 81 77 83 78 82 87 28 80 79 (COLORED RED) FIDESYS> mesh vol 88 89 91 90 17 3 (COLORED YELLOW) FIDESYS> mesh volume with not is_meshed (COLORED WHITE)

Resulting mesh

The constructed mesh looks like this, Fig. 2:

Fig. 2 - Resulting mesh.