Within the Cadfil system the starting point is the definition of a surface which is the basis for the winding. For rotationally symmetric parts this surface definition can be created in the Cadfil mandrel editor, can be parametrically defined or can be imported via standard CAD interfaces.
Having defined a mandrel a series of Filament Wound Layers (FWLs) are created that build up the structure of the component that is being developed. In doing this Cadfil understands the opportunities and constraints of the winding process and allows the user to create structures that are feasible to manufacture. Each FWL has a payout path file (PAY file) which describes the path on the part surface and an associated 3D path for the filament winding machine control point. There is also a TH2 file which contains a thickness and fibre orientation description for each of the FWLs.
A series of filament wound layers can be combined to make a combined winding (CTL file) which is in effect a playlist of FWLs, the combined winding editor also automatically creates a playlist of TH2 thickness files. At this point a user can send the combined winding to the Post Processor and with the additional of user defined control parameters and a winding machine configuration file a complete motion control program for the target CNC or Robot winding machine can be made. Alternatively the list of thickness files can be used to create detailed FEA models.
The mandrel (part surface) definition used for creating the winding model in general may not be totally suitable for the basis of a FEA model. For example the user may wish to discretise the surface in a different way to capture greater detail in areas of high stress or changing stress states. Consider the two figures below where the divisions of the cylindrical part of the pressure vessel have been changed to have more visions on the cylinder and a closer spacing near the connection to the domes
This redefinition of the mandrel to make an FEA or master mandrel can be quickly and easy done in the Cadfil mandrel editor. It is also possible for the user to create a geometrically compatible FEM shell geometry (nodes and elements) and import this into Cadfil as the base model for the Cadfil FEM.
The base geometry (Cadfil master mandrel or imported FEM geometry) and the thickness file list are the basic input for the FEM creating. Via a Cadfil graphical user interface shown below, the user specifies the output flavour (e.g. MSC Nastran, NX NAstran, Altair Optistruct, LS-DYNA, ABAQUS etc and parameters of what features to output (e.g. load and Boundary conditions) and a number of other job control options to fine tune the output. Importantly the user selects the type of FEM model such as Shell, cyclic symmetric solid slice, full solid (thick 3D shell) or maybe a detail solid shell with multiple through thickness elements. There are also a number of other outputs that can be specified such as Excel tables, HDF5 file, IGES file profiles etc. These are described more fully in other pages
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Last modified 28/10/2022