Study on robust structures (2nd report, classification of robust structures and comparisons of reference functions for upper design process)

Problems on robust structures are classified and examined from the point of view to obtain more suitable structures in the upper design process. The design method proposed by one of the authors in a previous report can be utilized for the design of robust structures in a narrow sense; however it is also pointed out that much attention must be paid to the selection of reference functions for the design of robust structures in the broad sense. In this paper, we initially treat the static problems where an elastic strain energy is chosen as a typical reference function for static problems of robust structures in the broad sense, and two kinds of performance indexes are discussed. One of them consists of the elastic strain energy and the other consists of the sensitivity of the strain energy to design parameters. Robust structures are designed by minimizing the value of the performance index. Here, general characteristics of these performance indexes are focused on and discussed using numerical examples. It is clarified that the robust structure for static problems in the broad sense can be effectively designed using these performance indexes for most cases, but there are cases where these performance indexes could not be always applied. Therefore, a different kind of performance index for robust structures in a broad sense must be developed in future studies.