*3.2.2 Concepts development and selection*

*New Innovations in Engineering Education and Naval Engineering*

summary of his design approach.

*3.2.1.1 Requirements and constraints*

• Handles 200 L with 30% spare capacity.

• Professional and pleasing appearance

mechanical engineering workshop.

'analysis-synthesis' barrier in undergraduate MED. A group of six students had initially been tasked and guided to design and construct a variable temperature and viscosity fluids mixer for a home-cottage cosmetics factory within a period of 6 weeks. The mixer is shown in **Figure 9**. After the project, one of the students was involved in a serious road accident which disabled him, and prevented him from doing the normal pre graduation industrial attachment. To enable him graduate however, he was assigned a new individual design project under supervision of the author at the university. He was to use his experience in the class project, to design (not construct) a herbal oil extractor, again for a home cottage factory. Below is a

*A home cottage industry 'Two speed' fluids mixer—as designed by MED students left—the assembled unit. Right—the counter-rotating slow speed mechanism (Watch online video at: https://www.youtube.com/watch?*

A machine needed to be designed for use in extraction of essential oils from African herbs. A full design with drawings (mechanical, electrical and hydraulic) was to be completed so that students could manufacture and test the

• Filtered liquid product must be extracted separately from the spent herbs.

*3.2.1 Identification of needs and formulation of engineering problem(s)*

• The extraction temperature must be between 70 and 80°C.

• Operates on domestic single phase 220–240 V AC power supply.

• Feed herbs are received cut into pieces smaller than 10 mm in length.

• Students must be able to manufacture all custom designed parts in the CPUT

**80**

machine.

**Figure 9.**

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The student considered five concepts as shown in **Figure 10**. He settled for concept number 3 on account of ease of manufacture, minimal heating element corrosion risks, and maximum heat transfer area, thereby reducing heating time.

### *3.2.3 Detailed design and specifications*

Having selected the mode of heating for the herbs, the student laid out the design as in **Figure 11**. Then he did a detailed analysis of the chosen concept in virtual form to give specifications in **Table 3**, followed by detailed engineering drawings of each machine element in the system.

#### **Figure 10.**

*Herbal oil extraction: different heating concepts [33].*

**Figure 11.** *System layout for a small scale herbal oil extractor.*



**83**

*Mechanical Engineering Design: Going over the Analysis-Synthesis Mountain to Seed Creativity*

In this chapter, we have described and illustrated MED from both a classroom perspective and from an industrial one. In undergraduate MED, emphasis is on ability to analyse existing systems. The student is taught MED on a machine element by element basis—and most contact hours are spent that way. There is little room and time to integrate the elements in one worked example or problem. Moreover, those elements from other areas of mechanical engineering, such as in Thermo-Fluids, are normally assumed to be well covered in those subjects. They are rarely given consideration in normal MED class rooms. This is not to mention the even more critical considerations of non-science related issues which, in the first place, are often, the source of problems to be solved by engineering. It has been argued in this chapter that this treatment acclimatises the student to always be expectant of readymade systems to analyse. Even then, understanding how the systems came into being, as answers to specific human needs, can be problematic. This is a disservice to the student and to industry, because the main purpose of MED is supposed to be synthesis of mechanical systems, speaking to the needs of society. Industry on the other hand, has no choice but to face the design challenge from a problem solution perspective. All areas of knowledge, be they from science, art, or even heuristic and intuition, are brought to bear on the problem. Market, economic, political, legal, social, aesthetic and ordinary engineering constraints are imposed on an inexistent system that is supposed to be created and made. Two largely complementary approaches of doing so were reviewed: the creative, and the rational. It was seen that the rational approach formalises the design process and tends to take care of more constraints a design may be encountering. It is thus advisable, even of creative designers to embrace it.

In engineering classrooms, it is without a doubt, the recommended approach.

normal in MED as commonly taught/learnt.

Two design examples were described in a university setting environment. One was primarily of creative nature, leading to an invention over a long period of time. However, whether consciously or otherwise, it was still tempered with some formality in form of a structured approach between different design stages. The main advantage of this approach seemed to be the generation of other offshoot products arising from apparent failures within the creative process. In essence, therefore, creativity can lead to many other originally unintended, but useful products. The second example was focused on the rational approach—as taught to the author's students. A physically handicapped student was able to demonstrate that he had learned the methodology by designing a product quite related to what he had learnt—and participated in building in class, while still physically fit. Importantly, he demonstrated good understanding of the integrative nature of MED, calling on subject content from diverse areas like Fluid Mechanics, Heat transfer, Electrical Technology, Economics, etc. Moreover, the problem to be solved required him to appreciate compositions of some naturally occurring plants and means of getting useful extracts from them. Such extensive exposure is not

To conclude the chapter, it could be said that—although the traditional approach of handling MED is helpful in so far as it breaks up the subject matter into smaller, easier to learn, topics, it makes it more difficult for students, and possibly academics, to apply that knowledge to solve real life engineering design problems. This author recommends a mixed approach whereby, early on in the study of MED, the current topic-based system is used but a formalised needs-driven design approach is gradually introduced until it becomes the dominant approach by the time the student is finishing her/his MED subjects. **Table 4** summarises the salient differences in approach. It is to be understood here, that we are not talking about the final year design project, typical in many engineering schools and faculties. No—it is the timetabled MED we are referring to. The new approach not only works, but it produces tangible results as demonstrated in this chapter. It should therefore, as much as possible, be adopted.

*DOI: http://dx.doi.org/10.5772/intechopen.85174*

**4. Summary and conclusion**

*Mechanical Engineering Design: Going over the Analysis-Synthesis Mountain to Seed Creativity DOI: http://dx.doi.org/10.5772/intechopen.85174*
