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The sphere parametric automatically creates multiple winding programs for providing a mufti-angle layup on spherical components. The programs give near uniform thickness distribution particularly if the filament bands are thin and a large number of layers are used. Because multiple wind angles are used the resulting composite is effectively in-plane quasi-isotropic and this gives maximum efficiency for a spherical pressure vessel. Ultra-high performance pressure vessels have been produced and tested using this method.
The user defines the sphere geometry (radius and end opening radius) and material parameters such as the band width and the number of individual winding angle that are required. The program then creates all the necessary winding path information and transition paths that wind from the end point of one path to the start point of the next. The parametric program is invokes from the QuickCAD options of the Cadfil main menu. This is documented elsewhere in this manual. A sample file call SP1.PAR is supplied in the EXAMPLES directory.
The program generates a series of .PAY files for example if the parametric data was in the file SP.PAR the software would generate SP01.PAY, SP02.PAY, SP03.PAY....... A maximum of 99 payout files can be created. Note that on DOS systems the maximum filename before the extension is 8 characters and hence the stem name the user supplies should not exceed 6 characters. A special control file SP.CTL would also be created. When the data is post-processed the .CTL file identifies all the individual .PAY files such that they can be automatically processed in sequence to create a single NC data file.
There are currently three possible variations on the Sphere parametrics these are shown on the parametrics menu as SPHERE2 and SPHERE3.
SPHERE2-Equal Openings with user specified wind angles
This parametric is for vessels with equal polar end openings the users specified the number of layers and the ply angles required for each layer. The clearance envelope is spherical with a cylindrical clearance around the shaft(s)
SPHERE3-Equal or unequal openings with automatic wind angles
This parametric is for vessels with equal or unequal polar end openings the users specified the end openings and the number of layers. The ply angles required for each layer are calculated automatically. The clearance envelope is spherical with separate cylindrical clearances for each shaft. The polar opening at one end can be zero or can be specified that the band crosses partially over the pole.