Computers make airplane design easier

As we enter a period of high inflation, the aerospace industry is at a crossroads. While trying to hold the line on cost, managers are faced with growing customer and governmental requirements and the need for significant technological advances: particularly improved performance and efficiency, longer life, and environmental safeguards.

To help solve these problems, aerospace is investing heavily in new computer systems. The key to the future, they believe, lies with computer-aided design (CAD) and computer aided manufacturing (CAM). Of all industries, aerospace is pursuing these new technologies the most aggressively.

Using computers in manufacturing is not entirely new. Some aspects of CAM have been used in aerospace for over 25 years. This effort began in the late 1950s when it became necessary to develop better ways to control factory machine tools.

Computer-aided design, however, is relatively new, emerging as an experimental tool in the early 1960s.

Traditionally, engineers have hand-drawn a series of two-dimensional line drawings, or blueprints, for each of the myriad of parts that make up a modern airplane. Next, the manufacturing operation must use these to create solid objects. The entire process is streamlined when the engineer creates three- dimensional representations in the computer. Today's wide-body commercial airliners have as many as 100,000 structural components. The engineering description of these components may take as many as 20,000 drawing sheets. With manual techniques, it is almost impossible to achieve complete design continuity between the sheets. Thus, it is not uncommon for a significant number of manual drawings to contain some sort of errors. These are generally not detected until after toolling has been made and parts are being fabricated in the factory. Therefore, correcting them is quite costly. By using computer accuracy to eliminate these expensive errors during the design stage, Boeing is expecting to recover the cost of implementing the system repidly.

The keystone of CAD/CAM is interactive computer graphics (ICG). Computer graphics allows the engineer or drafter to interact with the computer to create, view, and, to a limited degree, analyze geometric shapes. These shapes are displayed on a cathode ray tube, much like a home telvision screen. The designer operates this system using a typewriter-like keyboard. When he has completed a design, the data representing the engineering drawing are stored in the computer's memory. These data are fed into automatic plotting machines for producing drawing copies and may be transferred directly to manufacturing.

Most of the computer graphics systems now commercially available have several limitations that hamper the full realization of the technology. Factory machine tools generally require the geometry of a part to be described using surface representation. Most graphics systems have a limited capability for surface definition and are not yet mature in managing large volumes of data.

Implementation of CAD/CAM has been no easy task for aerospace. With the complexity and size of aircraft, any venture to significantly improve the engineering and manufacturing process requires a major capital investment. This investment is running into the tens of millions of dollars.

Once systems have been adopted, there are many new challenges to be overcome. For instance, whole engineering departments must be retrained to use the sytems. Also, who controls this computerized data and amount of reliance that should be placed on it has to be established. The hurdle of getting the Federal Aviation Administration to flightcertify parts designed wholly by computer -- without making drawings -- has not yet been crossed.

The prime benefits that aerospace is expecting to derive from its CAD and CAM systems include: increased manpower productivity, improved engineering quality, and the ability for engineering data to interface directly with factory machine tools. Individual manpower productivity increases have been identified up to 5: 1 and higher on some applications, but a ratio of 2:1 is probably more general.

Computer-aided design will also play an important role in the use of advanced , energy- saving materials in aircraft design. These weight-saving materials are called composites and consist typically of numerous layers of graphite filament bonded with expoxy glue. Where increased toughness is necessary, fiber glass is included as well. Producing these laminates, which sometimes consist of hundreds of layers, will require computer techniques to keep track of shape, end points, and direction of ply. Also, computer-design techniques will eventually provide the information necessary to automate the equipment that produces these fabrications, decreasing their cost and enhancing their structural integrity.

With the advent of CAD, in which most of the aircraft design is computerized, increased use of robots is feasible. A US Air Force-funded program, integrated CAM (ICAM), is aimed at automated aircraft manufacturing, emphasizing robotics.

These developments are raising some major questions. What long-range impact will CAD/CAM have from an overall corporation standpoint?what are the full benefits to be realized, and what new processes are around the corner? There are no complete answers to these questions, only informed speculation.

* Traditionally, engineering and manufacturing organizations have been separate and distinct entities. They may be merged into a total "design" factory. In such a complex, design and manufacturing personnel would work together to optimize design for efficient fabrication. Also, computer aid allows less highly trained people to design parts satisfactorily.

* The stringent aerospace quality-control process will likely undergo substantial change and be significantly automated. Scanning devices will be able to compare physical part shapes with the negineering computerized data base and detect small defects.

* Estimating and scheduling processes will undergo change. Statistics for designing components by old methods are no longer relevant. To provide manufacturing personnel with data they can best use may, in fact, take more engineering man-hours. But through the use of engineering-produced computerized data, the manufacturing operation may be able to reduce its overall costs significantly.

* There is concern in some circles that computing systems are becoming too integrated. With the old manual process, creativity and analysis are generally structured separately. The check and balance provided by these separated entities is now in danger of being eroded by vast singular computer systerms. An example of the problem comes from civil engineering. For the last 20 years, the civil engineering community has been encouraged to both design and analyze structures. As a result, the failure rate in this field is quite high.

Perhaps one of the largest challenges facing CAD/CAM is bringing academia into step with the way business now is being conducted in industry. Aerospace companies are spending millions of dollars to train recent graduates in needed computer skills. Colleges must face up to the need for modern computing systerms if they are to make a contribution to the development of this fast-paced process.

There are a number of major changes in the wind for the industrial designer as well.

* Systems that can recognize voice commands, instead of keyboard inputs, are being developed.

* Systems that model the geometry of objects as solids rather than as surfaces will probably be productive in two or three years, and in the 1990s designers will no doubt be using holographic (three dimensional) images.

* Aerospace engineers perform the most stringent and comprehensive structural-analysis studies of any industry.Because of the increasing complexity of these studies, they, in turn, are requiring increasing computer support. It is only a short step from this to have the computer completely synthesize the total design. The designer then would merely total design. The designer then would merely specify the general characteristics.

At the very least, significant changes in the way aerospace and other industries do business is upon us. The days of the old drawing board may, in fact, be numbered. I doubt that there has ever been such an exciting future for today's technical labor force, or correspondingly enormous challenges, for both industry and academia.

You've read  of  free articles. Subscribe to continue.
QR Code to Computers make airplane design easier
Read this article in
QR Code to Subscription page
Start your subscription today