Axonometric graphical presentation of deflection surfaces and internal force influence surfaces (Translation from Bulgarian) eng. Mario Behar          Introduction          The two programs presented here are made using the algorithmic language TurboBASIC for personal computer IBM PC-XT/AT and have the purpose to provide a visual axonometric graphical presentation of the stressed and deformed state of thin rectangular plates. In essence, the obtained pictures (Figs. 1 & 2) are influence surfaces for internal forces and deformations, in the presence of a unity external load, or simply surfaces of the same internal forces and deformations resulting from arbitrary external loads – different form unity.          Due to the practical impossibility to present all numerical data together with the graphics, this is done separately. This way, the output from the first program called “mb.exe” is practically only an indispensable add-on to this data. In its turn, the second program called “mbout.exe” is an add-on to the first program by offering the possibility to bring on the screen already prepared graphs without the need to again read the input file.          Input data          The “mb.exe” program works with data received from, and put in order by another program (for [mathematical] solution of [engineering] structures) called “SADAS” that works on a 32-bit EIM – ISOT1056 computer. The solution of the last mentioned program is based on the Finite Elements Method (FEM). In order to model the structure, element # 6 – shell (plate), has been used. The limiting conditions are as follows:          - the origin of the coordinate system to be in the geometric center-point of the plate;          - the plate to be subdivided in 10 x 10 finite elements (11 x 11 evenly distributed nodes);          - in order to enable [“mb.exe”] to read the data [from the SADAS program], in the very beginning of the groups of data used, labels must be introduced.          Both of the offered programs (“mb.exe” and “mbout.exe”) are able to work with already compressed data files.          Structure of the program          The block-scheme of the program “mb.exe” is shown on Fig. 3. The structure of “mbout. exe” defers from the one presented in the figure by not including blocks (3), (4), (4a) & (5b), while block (5) in it is called “Reading of data from graphic file”.          In their informative portion, both programs contain [equivalent] text in English and Bulgarian, while for the interface portion of the program only Bulgarian is used.          Output and capabilities of the programs          Both programs offer the following output options:          1) “mb.exe”:               - review of the numerical data (simultaneously with the graphics) for each separate node;               - print of the graphic screen;               - recording of the graphic screen in a file;               - recording of the graphic screen in a compressed file (shrinks the volume of the information by approximately 80%).          2) “mbout.exe”:               - print of the graphic screen without the date and hour that reflect the time when the graphic file was created (an option similar to the second option for “mb.exe”);               - print of the graphic screen with the above mentioned date and hour;               - recording of the graphic screen in a compressed file (an option equivalent to the last one for “mb.exe”).          Both programs offer a wide scope of informative and warning messages, that serve to guide both, along the work process, as well as when faulty situations occur. Both, “mb.exe” and “mbout.exe” offer the possibility to return to the beginning of the program or to any intermediate point of its body when it is necessary. Block (1) of both programs offers the option to go back and forth along the informative pages.          At each level of the program there is an option for unconditional exit from its body and return to DOS, as well as an option to remind the information that the introduction pages contain.          With respect to the process of creation of graphic pictures, the first program features the following:          - presentation together and in separate of the preexisting deformations (along the “Z” axis, i.e. normally to the plane of the plate) and those (along the same axis) – product of the external load;          - choice of whether to show or hide the [initially] unloaded “lattice” (the unloaded state of the plate);          - to show or not to show the vertical lines that connect the initial and deformed surfaces;          - to show or not to show the applied along the contour of the plate external forces (in the plane of the plate) and moments;          - to change the dimensions of the picture, as well as to change:            • the general scale of the graph;            • only the scale along “Z” axis;            • the axonometric angle.              The scale along the “Z” axis is determined automatically. The user of the program is able to change its value only in the range of (+/– 103), i.e. up to the extent necessary to expand or shrink the image along this axis.          - when recording the picture in a graphic file, the name of the latter is formed in such a way as to provide full information for:            • the output data;            • whether the picture represents internal forces or deformation;            • which specific internal force or deformation is being represented.          Conclusion          In case of interest shown by the readers, the capabilities of the programs with respect to number of nodes, order and source of input data, form of the plate, and other options can be expanded. An option to compute and to graphically present principal stresses can also be added to a future expansion of the programs. The current capabilities of the programs match the up-to-date specific needs of their author. Back to Top home ... other publications