The subject of this thesis is product development and design, based on a systematic approach. The study is based on [Hubka, V. Theory of Technical Systems. Springer Verlag, Berlin, Heidelberg, 1988] and the problem area is variance management and variation reduction due to increased product diversification.
The main purpose was to develop a methodology for the elaboration of the physical design and technical administration of a product assortment and to establish a theoretical basis for existing practice in industry.
The literature on engineering design science was analysed concerning terminology and underlying theories. The analysis showed that it is advantageous to separate the process of problem solving from the establishment of the characteristics of the object (product) and to look upon the description of the object, using four types of structures; process structure, function structure, organ structure and constructional structure. Simul- taneously a study was carried out in a number of Swedish companies, in order to analyse how product and production structures are handled in industry.
The Theory of Technical Systems has been used and expanded even further, in order to identify and formulate relations between the analysis of theory, mentioned above, and the established industrial practice. The constructional structure has been divided into one logical structure (identity, number etc.) and one physical structure (geometry etc.). By doing this it is possible to handle a number of different physical constructional structures with a single logical constructional structure, which means great advantages in the administration and control of the technical system (product), i.e. to be able to describe a number of product variants as one complex machine system.
In addition, different types of logical and physical constructional structures have been identified. The conditions under which they should be used have been analysed, and finally a methodology for the elaboration of constructional structures has been developed. This methodology is not a new model for product development, on the contrary, it is a synthesis of established theory of engineering design and of general theory of problem solving. Thus the methodology is iterative, i.e. the underlying principle is to work forward and backward between the different types of structures with the aid of alternating abstract and concrete forms of description.