# Function-Oriented Applicability Evaluation of Technical Folding Based on Expert Knowledge
## 3 Concept of the EvalTech Method
### Concept of Using the CBR System for the Applicability Evaluation  
In this paper, the applicability evaluation of technical folding is carried out by implementing the processes according to [PERSON] and [PERSON] [29] in a software application: _retrieving_ process and its specific subprocesses: _identify features_, _initially match_, _specify features_ and _select_. The _reusing_ and _reusing_ processes have not been implemented in this research paper. EvalTech ends with the _visualisation_ of those technical folding systems whose functions and function structures are most similar to the functions and function structures of the new product development task. Figure 3 below illustrates the elaborated process steps of the EvalTech method.  
Figure 2: Elements of the CBR system.  
The software-supported applicability evaluation starts with the subprocess _identify features_. In this step, the functions of the new technical problem (_new case 1_) can be defined with the support of the software application. The functions of the new technical problem are evaluated in the subsequent step, _initially match_. The functions are compared with functions of known technical folding systems (_case base 1_). If no similarity to technical folding systems is calculated, a folding system is most likely not an appropriate solution for the technical problem. In this case, consideration must be given to using a different principle solution for the technical problem. If there is an initial fit between the designed functions and the functions of known technical folding systems, the _specify features_ subprocess step is carried out. In the subsequent process step, _specify features_, relationships between the functions are determined based on the defined functions, and so the hierarchical function structure of the new technical problem is designed. This is followed by the calculation of the similarity between the designed hierarchical function structure (_case 2_) and the function structures of technical folding (_case base 2_) in the sub-process _select_. For the calculation of the similarity, algorithms are elaborated in Section 4.2 to answer research question 2, which finds the most similar _case_ based on attributes and the organisation of the _database_. The results of the similarity calculations are values between 0 and 1. The value 0 describes those _cases_ from the _database_ that have no similarity to the new technical problem and 1 those _cases_ with the highest similarity. Based on the result of the similarity calculation of functions and function structures, the software can recommend to the product developer whether technical folding can be applied to the new technical problem. If there is a low degree of similarity, a different solution should be selected for realisation.  
Figure 3: Elaborated process steps of the EvalTech method.  
The developed EvalTech method is implemented in a MATLAB(r) application to efficiently support the product developer. The method is initially tested using a concept development of one new product, cf. Section 6.