**5.2 Second experiment**

Once the formative process was known by the students and they provided their qualitative evaluation to such process. In the second experiment we proposed a methodology that students followed also by hand. The objective of this experiment was to compare qualitatively the freeform style previously experimented with our methodology to manufacture the 3D object by wire bending. Therefore, the second experiment was entitled "MDSU-based construction of 3D objects by means of wire bending". The MDSU is our proposed methodology. It stands for Mesh, Unfolding (*Desdoblado*), Separation and Union

TRIZ-Based Design of Rapid 3D Modelling Techniques with Formative Manufacturing Processes 181

physical modelling based on wire bending". Previous experiments were executed with the objective that students have well knowledge of the methodology and its complexity. This experiment was divided in two parts. The first parts consisted in a questionnaire that asked the students about the possibility to automate the MDSU methodology. The technical questions were oriented to design requirements. The second part of this experiment consisted on asking the students a design proposal for the machine. The proposals were done by teams of students. After a self-selected team formation the number of novice teams was 12 and the number of advanced teams was 15. Novice teams were composed by 4 or 5 members. Advanced teams were composed by 3 members. Teams were asked to propose two alternatives, choose and modelling one. Teams had one month to elaborate their proposal in a CAD platform. The experiment was concluded with the presentation of the proposals. Figure 4 shows two proposals from the novice teams and Figure 5 shows two

All experiments were executed during the semester August-December 2010. Post-analysis

proposals from the advanced teams.

was executed during the first months of 2011.

Fig. 4. Examples of proposals from novice teams.

Fig. 5. Examples of proposals from advanced teams.

**5.4 The proposed design methodology for rapid 3D wireframing techniques** 

As explained in Sections 4 and 5, the proposed process to design mechatronic systems for such new rapid three-dimensional physical modelling techniques is the following: first made freeform experiments by hand, second use the proposed MDSU methodology also by hand (the objective of this methodology is to reduce the complexity of the formative

(MUSU in English). The MDSU approach proposed here reduces the degree of freedom necessary in mechatronic systems to automate the process. These four sub-processes belong to TRIZ principles. Mesh and Separation match with the TRIZ Segmentation principle which consists on divide the object in independent parts. Recall that mesh is compared by finite element where each element is independent. Unfolding phase match with the TRIZ Flexible Shells and Thin Films principle which suggest to use thin and flexible surfaces instead of three-dimensional structures. A simplification of this principle to wireframing takes in consideration only the vertices. The last sub-process of our methodology (Union) match again with the TRIZ Segmentation principle; which consist on facilitating the assembly of the product. It is worth to say that none of the students know the TRIZ methodology and the only possibility to evaluate it is by means of proposing them a methodology inspired on it. Our proposed MDSU methodology is intended to reduce the complexity of making a 3D physical modelling machine and instead manufacturing a 2D physical model and then fold and union it to build a 3D object. We think that this formative manufacturing process is less complex. Furthermore, we are proposing this sequence of applications on TRIZ principles but other sequences might also be explored.

Students were asked to make sketches of the process. They were asked to make at least four alternatives (divergent phase). Figure 3 (right) shows a student work of this experiment. Once they finished the sketches, students were asked to choose on option (convergent phase) and executed accordingly (left figures). They made the experiment with plastic cups commercially available. The tools used by the students were mainly scissors. Finally a questionnaire was applied to the participant students. In the following section we will present the more important results of this experiment.

Fig. 3. Pictures from the second experiment.

#### **5.3 Third experiment**

The third experiment has the objective to find the best design to the machine automating the MDSU methodology. This experiment was entitled "Automated machine for rapid 3D physical modelling based on wire bending". Previous experiments were executed with the objective that students have well knowledge of the methodology and its complexity. This experiment was divided in two parts. The first parts consisted in a questionnaire that asked the students about the possibility to automate the MDSU methodology. The technical questions were oriented to design requirements. The second part of this experiment consisted on asking the students a design proposal for the machine. The proposals were done by teams of students. After a self-selected team formation the number of novice teams was 12 and the number of advanced teams was 15. Novice teams were composed by 4 or 5 members. Advanced teams were composed by 3 members. Teams were asked to propose two alternatives, choose and modelling one. Teams had one month to elaborate their proposal in a CAD platform. The experiment was concluded with the presentation of the proposals. Figure 4 shows two proposals from the novice teams and Figure 5 shows two proposals from the advanced teams.

All experiments were executed during the semester August-December 2010. Post-analysis was executed during the first months of 2011.

Fig. 4. Examples of proposals from novice teams.

180 Industrial Design – New Frontiers

(MUSU in English). The MDSU approach proposed here reduces the degree of freedom necessary in mechatronic systems to automate the process. These four sub-processes belong to TRIZ principles. Mesh and Separation match with the TRIZ Segmentation principle which consists on divide the object in independent parts. Recall that mesh is compared by finite element where each element is independent. Unfolding phase match with the TRIZ Flexible Shells and Thin Films principle which suggest to use thin and flexible surfaces instead of three-dimensional structures. A simplification of this principle to wireframing takes in consideration only the vertices. The last sub-process of our methodology (Union) match again with the TRIZ Segmentation principle; which consist on facilitating the assembly of the product. It is worth to say that none of the students know the TRIZ methodology and the only possibility to evaluate it is by means of proposing them a methodology inspired on it. Our proposed MDSU methodology is intended to reduce the complexity of making a 3D physical modelling machine and instead manufacturing a 2D physical model and then fold and union it to build a 3D object. We think that this formative manufacturing process is less complex. Furthermore, we are proposing this sequence of applications on TRIZ principles

Students were asked to make sketches of the process. They were asked to make at least four alternatives (divergent phase). Figure 3 (right) shows a student work of this experiment. Once they finished the sketches, students were asked to choose on option (convergent phase) and executed accordingly (left figures). They made the experiment with plastic cups commercially available. The tools used by the students were mainly scissors. Finally a questionnaire was applied to the participant students. In the following section we will

The third experiment has the objective to find the best design to the machine automating the MDSU methodology. This experiment was entitled "Automated machine for rapid 3D

but other sequences might also be explored.

Fig. 3. Pictures from the second experiment.

**5.3 Third experiment** 

present the more important results of this experiment.

Fig. 5. Examples of proposals from advanced teams.

### **5.4 The proposed design methodology for rapid 3D wireframing techniques**

As explained in Sections 4 and 5, the proposed process to design mechatronic systems for such new rapid three-dimensional physical modelling techniques is the following: first made freeform experiments by hand, second use the proposed MDSU methodology also by hand (the objective of this methodology is to reduce the complexity of the formative

TRIZ-Based Design of Rapid 3D Modelling Techniques with Formative Manufacturing Processes 183

necessary some kind of support to manufacture their proposals. 86% and 70% of novice and advanced students respectively think they do not need a kind of support to manufacture their proposals. Our interpretation is that advanced students have more skills and know more tools to develop their proposal and therefore they think in less percentage that they do

Because in the first experiment the students manufacture their proposals by hand, a question related to the use of special tools was applied. The results shown that 11% of the novice students and 100% of the advanced students think they need a tool to manufacture their proposals. Furthermore, students were asked about the type of manual tool they need. The results shown that 91% and 94% of the novice and advanced students consider they need tweezers. Other manual tools selected by the students where molds, folding machine,

An important question about cognition was applied to the students. The question was about generation of ideas about how to improve the formative manufacturing process. 40% and 35% of novice and advanced students respectively feel at 100% that they generate ideas during the experiment. These results show to us that hand manufacturing help to generate

Recognizing that the final model the students made was a wire-frame model of a 3D object. Students were asked about post-processes needed to finish a 3D object (mock-up). Among the post-processes students proposed are: finishing, structural support, covers, soldering unions, painting, etc. Of the most important for both students were finishing, fixing the

One final question about the complexity of the experiment was applied to the students. 8% and 9% of the novice and advanced students considered at 100% the experiment complex. Almost 80% of their appreciation falls between 50% and 75% of level of complexity with a more percentage in the 75%. We conclude that in general students of both levels considered

A set of questions were applied after the students executed the second experiment. There were almost the same questions that in the first experiment. These set of questions will help to us detect the impact of our methodology which is inspired in TRIZ principles. In this section first we will present the questions that are unique to this experiment then in the following section we will present the comparison between the first and second

The MDSU methodology was executed twice. With respect to the question about the unfolding the options for both executions are: separate the base and sectioned walls, keep the base with sectioned walls, base and walls sectioned, keep some section of the based together to the walls and other. In the first intend, 42% of the novice students chosen the second option while 42% of the advanced students chosen the first option. In the second intend both types of students exchange their choices. In general the first two options were chosen by both types of students. We think that students did not explore other potential possibilities because time restrictions on the experiments. We also asked to the students if the unfolding stage was confused and why. The results showed to us that almost half of the students consider confuse the unfolding stage. The most important reason why they

consider that the unfolding is confused is that was difficult to imagine the unfolding.

**6.2 MDSU-based construction of 3D objects by means of wire bending** 

not need a support.

scissors, imagination and none.

ideas (increase creativity).

support and covering the walls.

experiments.

the experiment with some complexity.

manufacturing process for the new rapid three-dimensional physical modelling technique), finally the designer is able to propose a machine (design requirements) for new rapid 3D wireframing techniques.
