Papers by Author: Haruo Sakamoto

Abstract: This paper describes codes and practice for designing welded structures such as railroad truck frames. For designing an initial configuration, rather simple criteria are desired, although most codes such as AWS, AISC, etc. are complex. They consist of a variety of welded joint categories, which make a designer feel difficult when deciding the initial configuration. Therefore, such codes are considered to be mainly used for the evaluation of designed and constructed structures, and not to be used for deciding the initial configuration. The JIS (Japanese Industrial Standard) for a railroad truck frame is explained as an example of a simple code, and is compared with some fatigue data. This standard is thought to be useful for a designer. However, the result of this investigation suggests a modification of the JIS for obtaining more reasonable criteria. Desirable criteria should be simple for a designer and sufficiently safe for structures. Additional fatigue data of welded joints, a statistical study for desirable non-fracture probability, and methods of structural stress analysis are to be researched in the future. A practical fatigue testing method is also needed for investigating the strength in a high cycle region such as 108.

Abstract: This paper describes the state of the art in design codes and guidance using fracture mechanics. In Germany, a railroad accident occurred in June, 1998, which resulted in about 100 passenger deaths due to a wheel fracture. In September, 1999, a water leak accident due to a crack in a pipe happened at the Tsuruga nuclear plant in Japan. Such serious accidents are the result of fracture events. Fracture mechanics is thought to be a tool to avoid such catastrophic fracture accidents. The state of the art in designing mechanical components or structures applying fracture mechanics was reviewed. The American Society of Mechanical Engineer, the Japanese Society of Mechanical Engineers, the Japanese Welding Society, and the Japanese Industrial Standard were mainly surveyed. This report suggests that a more consideration of fracture mechanics in the design codes and guidance is needed for avoiding fracture accidents in components or structures.