1. As indicated, the computer aided design program, AD-200012, and the structural analysis program, SPAR13, are interfaced with the data base management system, R11111'+(Relational Information Management System), through pre- and post-processors. RIM now serves as a prototype for the IPIP (IPAD Information Processor) data base management system which is being developed and is the focus of the current IPAD system development 15. Since IPIP will initially reside on a mainframe computer, i t was decided to use RIM on the mainframe computer and the designlanalysis programs would reside on the mini-computer to more accurately simulate the expected engineering environment even though RIM is operational on both the mini- and mainframe computers. To date, programs for generating and/or deciphering data associated with the design criteria, configuration parameters, section and material properties, and loads have not been incorporated into the system. Instead, representative type data has been manually stored in the data base. Presently, the finite element modeling capability is primarily accomplished by pre-processors which formulate the RIM data into a format suitable for input into the SPAR structural analysis program. However, there is an on-going effort toward the development of a generalized finite element modeler which will utilize the basic geometrical and design data that is generated in AD-2000 and stored in RIM. The present system is shown by the flow chart of figure 2.
2. In accordance with the design, analysis, and manufacturing process shown in figure 2, a structural design is created using the computer aided design capability of the AD-2000 computer program. Not only is i t possible to generate the geometry of the structure, but i t is also possible to assign design attributes (characteristics) to various entities or elements. For examle,a one dimensional line entity may be desig;lated as an 8 x 8 wide flange beam made of structural steel. This geometrical and attribute data can be extracted from the AD-2000 data base and placed on a file in some specified arrangement. Since the AD-2000 resides on a mini-computer and RIM is on a mainframe computer, software was developed for transferring the data file from the mini- to the mainframe computer. Once this data has been transferred, a post-processor called AD2RIM (fig. 2) formats the data for input into RIM, opens the data base, loads the data into previously defined relations for the various entities, and then closes the data base. The AD2RIM processor is a Fortran program which can access and modify the RIM data base through Fortran-callable subroutines. The relations are defined by the user interacting with RIM as shown in figure 2. This data can now be recovered for straight lines, triangles, parallelograms, ruled surfaces, and curved mesh surfaces. Methods for the recovery of this type data for curved lines, which are representative of such things as rib caps and fuselage frames, are presently being developed.
3. The joints or nodes are extracted from the basic geometry data, as generated in AD-2000 and stored in RIM, by the processor JNTSET. JNTSET is a Fortran interface processor which eliminates the duplicate nodal coordinates given in the AD-2000 data and then sorts and numbers the remaining unique nodes using only RIM control statements. These nodes are then stored in RIM for retrieval by the finite element input generator. The interface of JNTSET with RIM is shown in figure 2. This processor is limited to generating the sequenced joint locations for structures whose elements have been individually defined (i.e., straight lines, triangles, and parallelograms) as opposed to surfaces and curved lines which are composed of several elements. No attempt has been made at the present time to generate these sequenced joint locations for the surfaces and curved lines.
4. The JNTSET processor has some capability for sorting the nodal coordinates such that the resulting nodal numbering scheme will yield a suitable bandwidth for the stiffness matrix. However, the complexity of generating sequenced joint locations for a generalized structure, for purposes of minimizing the bandwidth of the stiffness matrix, requires computational capabil ities that are not available as RIM control statements. For example, sequencing nodes about a point or axis i n an angular manner would require the calculation of the angular displacement of 'each node. At other times, it-may be easier to generate the sequenced nodes and corresponding element connectivity by developing a computer program which uses the AD-2000 geometry as input. Prior to the release of RIM, a program called ADSPAR, which generates the nodes and element connectivities of line segments, triangles, and parallelograms, was developed and interfaced directly with the AD-2000 program as shown i n figure 2. This program has been modified to include the capability of generating sequenced nodes and element connectivities for ruled and curved mesh surfaces. The processor, JNTSET, and program, ADSPAR, will finally be merged into a single processor which will utilize the best features of each for generating sequenced nodes. Element connectivities will be solely generated i n the processor SPARIN.
5. The generation of a N/C (Numerical Control) cutting path and i t s corresponding APT (Automatically Programmed Tools) source f i l e i s an integral part of the AD-2000 program. This source f i l e i s edited by the user to remove extraneous information and to include some additional statements tb ident i f y the Ii/C machine part and for stopping the tool movement at selected intervals (i.e., when a tool change i s required). It i s then necessary to transfer the f i l e to the mainframe computer where the APT language compiler exists for this particular system. The APT compiled f i l e i s then executed to generate plots of the tool paths for check-out and a nvlar tape for mounting on the appropriate N/C machine. The N/C machining capab i l i t y is indicated on figure 2.