CATIA (Computer Aided 3-Dimensional Interactive Application) (in is a multi platform CAD/CAM/CAE commercial software suite developed by the French company Dassault Systemes and was marketed worldwide by IBM. Written in the C++ programming language, CATIA is the cornerstone of the Dassault Systemes product lifecycle management software suite. Thousands of companies of the world use CATIA for their product design and the suppliers providing tools and other products to those companies also use this software for the same purpose. In other words CATIA is easy designing software used worldwide.
Giving the user easy 3D modeling interface CATIA has been first choice of designers working in automotive and aerospace industry. Other industries include Architecture, Automotive, Construction, Electronics, Medical, Furniture, Machinery, Mold and Die, Consumer Goods and Shipbuilding. Even big research centers like NASA use CATIA to design their space shuttles. In aerospace The Boeing Company, Airbus, Bombardier Aerospace, EMBRAER, Vought Aircraft Industries, AgustaWestland and many other companies use CATIA for the development of their aircrafts.
CATIA supports multiple stages of product development (CAx), from conceptualization, design (CAD), manufacturing (CAM), and engineering (CAE) .CATIA provides different workbenches for facilitating collaborative engineering which includes surfacing & shape design, mechanical engineering, equipment and systems engineering and even reverse engineering.
These workbenches provide interface for the user to complete different stages of designing, analyzing, developing the product till creating final file form for its production. It allows creating 3D model from 2D sketch and vice versa. It also facilitates material assignment to the created part and analysis interface to analyze factors like weight and inertia before the production so that one can determine whether or not the product will satisfy the requirements and estimate production cost.
Starting from conceptual design itself CATIA has been used to design and analyze each and every little detail of our aircraft model. This will be briefly explained in the next section.
AutoCAD is a software application for computer-aided design (CAD) and drafting. This software supports both 2D and 3D formats. Developed and sold by Autodesk, Inc., AutoCAD is Autodesk’s flagship product and by March 1986 had become the most ubiquitous microcomputer design program in the world, utilizing functions such as “polylines” and “curve fitting”.
AutoCAD allows better accuracy than the hand drafting method that was traditionally used. Latest AutoCAD version includes full set of basic 3D solid modeling tools but lacks advanced tools. AutoCAD allows
information such as areas and volume from an existing drawing to be stored in another software format such as spreadsheet.
ProfiliV2 is a user-friendly version of Xfoil. This software is mainly used for generating airfoils and analyzing them. Its database consisted of more than 2200 airfoils. From this database, suitable airfoils can be filtered out on the basis of their aerodynamic properties. Some of them can even be tweaked to obtain the desired properties.
In our designing after careful analysis suitable airfoil is exported from Profili create its 3D modeling in CATIA.
DESCRIPTION OF SOFWARE USE
During the design process all of the above software were used. Profili and AAA are used to create the ribs in CATIA. The steps involved are listed below:
First airfoil of desirable aerodynamic property is selected in Profili and is exported to .txt file. Then the file is opened in notepad to remove all the alphabets and space inside the file with only the points remaining and saved. Next the file should be copied to the same location as the executive file of AAA software is located. Then the AAA software is executed whereby the file name and chord length of the airfoil to be created is inputted in following format as shown in the figure below.
Here, NACA 0012 airfoil is to be created with chord length of 75mm. After clicking the start button CATIA interface opens and the airfoil spline curves are created.
Some airfoils such as NACA 0012 may not have joint trailing edge while importing. This can be edited in Profili to extend trailing edge upto certain length to form the desirable curves or it can be extrapolated in CATIA under Generative Shape Design workbench like in figure 3.4.3, since its effect to the aerodynamic performance is negligible.
Then the extra part of the curve can be cutoff and joined using respective command and using Part Design it is padded to form the three dimensional rib structures.
Pockets are created in the structure by sketching 2D drawing in one of the plane to form the required features.
After this, designing all the ribs of wings, canard and vertical stabilizer is easily completed. Now, other parts of the aircraft are to be created. Some of them are individually created under part design while others are created inside the Assembly Design.
In this project, I designed the frames of fuselage individually. Like mentioned before, two work benches were exclusively used under Mechanical Design Part Design and Assembly Design. Then they are imported in assembly design workbench and are assembled assigning constraints to place the frames at the precised distance. Similar are the ribs of wing, canard and vertical stabilizer assembled together. After this is done, next work is creating other details in the structure like spars, stringers, longerons, mounting plate, base plate, etc.
Sometimes assembling can be very challenging, especially if the parts are to be created in angular or in non symmetrical planes. In such times under Mechanical design workbench lines and planes feature can be used to sketch such parts. Sometimes 2D drawing in 3D view can also help ease the task.
Once the parts are formed in CATIA, Drafting is used to draw the front view of the parts into a worksheet. This is done to export a file compatible to AutoCAD. The worksheet can be modified to required dimension. Then all these files are opened in AutoCAD for the final product creation via LASER Cutting Machine.
NEXT: CHAPTER 4