The gas cutting process is one of the primary methods employed for cutting steel sheets. However, during gas cutting, the adhesion of slag to the back surface of the steel plate cannot be avoided. In this study, to prevent slag adhesion on the bottom plate, the bottom plate was coated with an iron oxide paste. Several aspects such as the effect of iron oxide paste on slag adhesion, discharge and separation of slag from the steel plate’s back surface, and the formation and growth of adhesive slag were experimentally investigated. Consequently, based on the concept that slag is separated from the steel plate with paste, it can be concluded that the proposed iron oxide pasting method aids in easy removal of adhered slag.

Researchers in the design engineering domain have devoted to developing various tools and methods which support new product development activities. However, fewer research works are surveying their utilization in industries, and few works focusing on its trend during a specific period. This research aims at clarifying how much design tools and methods have been utilized in Japanese industries in the last decade, and what factors promote or disturb their effective utilization. First, this paper reports a questionnaire survey performed in 2014 on the usage of various tools and methods in the product development process of Japanese manufacturing industries. Its results are compared with those of the survey carried out in 2002. Three metrics are set to evaluate the utilization: awareness, usage, and effectiveness. The analysis of the questionnaire survey can roughly reveal some trends of the use. In addition, this research interviews to analyze detailed situations. Analysis in the changes of the three metrics during the decade and the interviews reveal factors behind those trends.

Fiber reinforced composite materials used in the aerospace field principally consist of a laminated shell structure manufactured by laminating prepreg sheets at various angles. Although such structures have the advantage that freedom of structural design is high since the mechanical properties depend on the laminated structure, buckling due to thinning of the shell is likely to occur because of weight reduction requirements. Therefore, it is necessary to design an optimal structure to maximize buckling strength. However, for optimal structural design of the laminated shell structure, it is difficult to find an optimal solution by a general optimization method because there are a large number of both discrete and continuous value design variables. In this study, we proposed a new method for calculating optimization operations to solve the buckling load maximization problem of laminated shell structures. A new method has been applied to a particle swarm optimization algorithm (PSO_NDT) that includes nonlinear dissipation terms to the inertia coefficients of all design parameters of discrete and continuous values. Additionally, a new method has been applied to a hybrid PSO algorithm (HPSO_NDT) combining PSO_NDT and the conjugate gradient method, in order to improve search performance and convergence of PSO_NDT. From analysis results of buckling load maximization problem of laminated shell structures, it is demonstrated that HPSO_NDT can find optimum solution with a smaller number of evaluations than other algorithms.

One heat treatment condition for carburizing and quenching process is usually selected in order to be satisfied with the required specification. Therefore, to satisfy to various specifications, it is required to prepare and produce several heat treatment conditions. If it is possible to be satisfied with various specifications by conducting the Repeated Carburizing and Quenching instead of maltiple heat treatment conditions, the flexibility of production process increases. In this study, the effect for carburizing depth and so on by performing the Repeated Carburizing and Quenching Process is clarified by experimental examination and the following results are obtained. The carburizing depth of SCM420 steel which is carburized by the Repeated Carburizing and Quenching process increases according to carburizing time and it is clarified that the depth of carburizing is estimated by Harris formula. It becomes to be able to predict the carburizing depth by the Repeated Carburizing and Quenching process and to control the surface remained austenite. The flexibility of carburizing and quenching process may increase. It should be careful that the grain growth caused by the Repeated Carburizing and Quenching may occur depending on the Repeated Carburizing and Quenching conditions.