# Function-Oriented Applicability Evaluation of Technical Folding Based on Expert Knowledge
## 1 Introduction  
In its traditional form, the Japanese art of paper folding enables the creation of various three-dimensional shapes by simply folding two-dimensional sheets of paper. In recent decades, this so-called origami principle has increasingly become an effective source of inspiration for engineering solutions [1]. In engineering solutions, the origami principle is actualised as technical folding. Technical folding systems do not consist of thin paper like origami folding, but of thick, rigid panels that are additionally connected to each other by joint elements. Due to their foldable structure, technical folding systems can realise lightweight structures that have a high load-bearing capacity. The application of technical folding according to this definition is the subject of the research paper.  
Scalability and flexibility of technical folding, its inherent motion, and the possibility of reconfiguration offer high potential and versatile benefits in fields far beyond art and aesthetics. Up to now, technical folding has been applied in the following fields of engineering application: Industrial Packaging [2; 3; 4], Optics [5; 6], Biomedical Engineering [7; 8; 9], Robotics [10; 11; 12; 13; 14], Aerospace [15; 16], Consumer Products [8; 17; 18], Electronics [19; 20], and Architecture [21; 22]. However, these applications represent singular solutions, meaningthat the overall prevalence of technical folding is low. Infrequent application of the solution principle of technical folding in the context of product development is mainly due to the following challenge. In early phases of a function-oriented product development process, product developers without high expertise in technical folding are not able to decide whether technical folding is a suitable solution principle for their technical problem because:  
* The solution principle of technical folding and its application is largely unknown in industrial practice.
* No (software-supported) methods exist that adequately support the decision-making process.  
Thus, non-expert product developers can potentially make decisions for or against the solution principle of technical folding without knowing the advantages or disadvantages of it compared to other possible solution principles. In order to solve these challenges and effectively strengthen the application of the solution principle in industrial practice, an evaluation process should be defined. To address challenge (a), expert knowledge about technical folding systems must be elaborated and made available for a structured and effective decision-making process. For example, development data of known technical folding solutions from the literature can be used to define expert knowledge. This expert knowledge should then be formalised in such a way that it is comparable with the information available for a new technical problem in the early phases of a function-oriented product development process. Based on the formalised expert knowledge, in order to address challenge (b), a structured and effective decision-making process must be developed that adequately evaluates the applicability of technical folding to a new technical problem. The process enables the reuse of expert knowledge, the continuous expansion of expert knowledge to include newly developed technical folding solutions, and thus an increasingly precise evaluation based on expert knowledge. In order to efficiently generate objective and consistent decision results and to facilitate the decision-making process for inexperienced product developers, the process developed here should be implemented in software. The method on which the process is based is referred to below as EvalTech.