Most car body parts are manufactured using thin plates to reduce their weight, and completed assemblies typically have numerous spaces. Because cars are not designed to be completely watertight, rain or wash water may leak into the interior spaces of the assembly through gaps or inlets. When water enters a space and is not drained sufficiently, it can fill the space and overflow into unexpected channels, causing severe problems such as part corrosion and electric shock. In our research, based on a decomposition model representation, we have developed a program to graphically simulate all possible flows within the interior spaces between car parts. Our program can simulate the locations of outlets and overflow channels into unexpected regions, and thus help designers verify the effectiveness of their designs before manufacturing, which can therefore reduce the development time and costs. In particular, since the program can simulate overflow when a car in both horizontal and inclined positions, it can prevent possible design errors by engineers who are accustomed to designing cars only in a horizontal orientation. Our developed method can also be applied to aircraft and ship designs.

Automobiles, aircraft, and ships require tremendously many parts to be assembled. For developing such large assemblies, most companies accelerate the design process by having many design engineers in different functional or sectional design groups working concurrently. However, interferences and gaps can be found when the parts and sub-assemblies of different design groups are to be assembled. These error cause design changes and additional repair processes, resulting in an unexpected increase in costs and time delays. While the interference problem has been resolved by digital mockup and concurrent engineering methodology, many cases of the gap problem in the automotive industry have been covered by temporary treatments when the gaps are small enough to be filled with sealants. This kind of fast fix can cause leakage into the engine chamber and passenger cabin when the gap size is too big for filling or when the sealant gets old, which can turn fatal. With this research, we have developed a program to automatically find gaps between the parts of an assembly so that design engineers can correct their designs before the manufacturing stage begins. By using the method of decomposition model representation, the program can visualize gaps between complex car body parts as well as estimate their volumetric information. It can also automatically define the boundary between a gap and the exterior space. Although we have reviewed the benefits of the program by applying it to car development, it can also be applied to aircraft and ship designs comprising several parts. (C) 2014 Elsevier Ltd. All rights reserved.

Large number of part design for aircraft and automobile is preceded by functional or sectional design groups for efficiency. However, interferences and gaps can be found when the parts and sub-assemblies by those design groups are to be assembled. These interferences and gaps cause design changes and additional repair processes. While interference problem has been resolved by digital mockup and concurrent engineering methodology, gap problem has been covered by temporary treatment of filling gap with sealant. This kind of fast fix causes fatal problem of leakage when the gap is too big for filling or the treatment gets old. With this research, we have developed a program to find the gap automatically among parts of assembly so that users can find them to correct their design before manufacturing stage. By using decomposition model representation method, the developed program can search the gap among complex car body parts to be visualized with volumetric information. It can also define the boundary between the gap and exterior empty space automatically. Though we have proved the efficiency of the developed program by applying to automobile assembly, application of the program is not limited to car body only, but also can be extended to aircraft and ship design of large number of parts.