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DESIGN COMPONENT IN LABORATORY COURSES By Satyaprakash Das
Dept. of Engineering Science and Physics, College of Staten Island, NY 10314. Abstract The requirement of design in every aspect of engineering instruction has been the mantra of the ABET evaluation teams for quite sometime. The abolishment of bean counting procedure in design requirement has put the onus on the faculty to develop curriculum that expose the students to design process at every possible opportunity. The availability of interactive software in every field of engineering has largely accomplished the "what if" type of activity and to an extent even a detailed analysis which is crucial for understanding the design process. But this has been limited to classroom instructional activities only. The other aspect of the design process namely,the trial and error process of building , testing and refinement which is extensively used in reality has not been given adequate attention. The only place where it is emphasized is in a capstone design course. Traditionally, laboratory courses do not involve an open-ended type of experiment . Students make a set of observations and are asked to verify the laws or principles based on the theory . This article describes a unique approach to introducing students to the building testing and refinement process in a traditional laboratory curriculum. Specific examples of experiment that accomplish these goals will be presented. The challenges and the rewards of developing such a curriculum will be discussed.
Introduction The concept of design is of paramount importance in engineering education. Unfortunately, there has always been a conflict between the engineering science and the design in engineering instruction. The importance of design has been the cornerstone of the evaluation of an engineering program by the ABET. In the early years of evaluation each and every course in a program was evaluated for its design content, which led to a highly controversial approach namely "Bean counting Technique". Although the ABET rightly rejected this approach because of its inherent fault, it still requires that an engineering program should have a strong emphasis on engineering design at every stage of instruction. This has put tremendous pressure on educators to develop curriculum aimed at using design challenges while simultaneously made to learn engineering fundamentals. In the early stages of the implementation of this philosophy, educators developed several exclusive courses to expose the students to the design experience. Unfortunately, including these courses in the pre-major or major requirements led to an increase in total credits for graduation-which was at odds with the administrators who were reducing the credit requirements for graduation in resonance with the regional and national trend. Now, the challenge was to incorporate the design experience in the existing courses without increasing the total credits to graduate. This new paradigm of "Design at every stage" required a totally different approach to teaching engineering with a delicate balance between engineering science and design. To an extent the mushrooming of several engineering texts with software has facilitated this, which allow the student to experiment with open-ended problems. In fact, the students do spend an enormous amount of their time on problems based on the design aspects. What are really lacking at this point in time are the hands on experience the student has in the traditional engineering program. The concept of design- build –test and evaluate (DEBTE) has been the buzzword in the industry and it is imperative that the institutions train the future engineers in this area as well. Usually, Engineering programs have a capstone design course at a senior level where the above concept is introduced to the students. But with the increasing demand from industry and ABET for more exposure in this area, it has become necessary to introduce this concept wherever possible. Obviously, it’s difficult to put "DEBTE" in theory courses and the only place where it can be introduced is in laboratory courses at perhaps junior and senior levels. One needs to be careful in developing such a curriculum since it has to accomplish the goal of introducing DEBTE while emphasizing engineering science and design concepts. Two such examples, which were introduced at junior –senior level of laboratory experience, are presented in this paper.
Design in Laboratory Environment The two laboratory courses where the DEBTE concept has been introduced are the Mechanical Materials Laboratory (ENS 359) and the Applied Mechanics Laboratory (ENS459) at the junior and senior level respectively. These labs meet for 4 hours once a week for 14 weeks. The original approach to teaching these laboratory courses was to design a set of experiments for the students to perform during this period. The experiments were so chosen to reinforce and test the various engineering principles learned in the classroom. But there was very little scope for the students to follow the DEBTE concept. In the new approach, although students follow the same methodology for the first eleven weeks the last three weeks are devoted to introduce experiments based on DEBTE concept. In doing so they not only verify the engineering fundamentals but also learn the project and time management skills that are very critical in industry. One such experiment, which was introduced in the Materials Laboratory (ENS 359), was the Thin-walled cylinder experiment. Here the students make use of the principle of strain gages which was introduced to them in an earlier class to test and evaluate the axial and hoop stresses in a pressurized can of drinks. Typically, they are asked to estimate the pressure in the can and also verify the stress relation for thin-walled cylinder from the theory. The students learn to experiment with strain gages the type of mounting and the nuances involved in mounting them on the can. Such an experience will prepare them to appreciate the complexity involved in bringing a design on paper to fruition. Another experiment that was introduced in the Applied Mechanics Laboratory (ENS459) was to illustrate the concept of natural frequency of a structure by means of forced –vibration tests. In this experiment, the students are required to find the natural frequency of a free-free beam experimentally and compare it with the theory. The students are given a choice of materials available to them. They are also given a shaker and all the instrumentation that is needed for testing. Since the students at this stage are already exposed to basic measurement techniques, they only need to decide on the material dimension and all the electronic operations of the transducer and mounting techniques. Such an exposure will give them the hands on experience of building, testing and evaluation and the difficulties associated with it. Although only two experiments in this area are presented here, experiments in all areas of engineering can be suitably incorporated in the laboratory curriculum.
Conclusion The attempt to introduce the DEBTE concept in laboratory is encouraging, but not without difficulties. There needs to be a greater cooperation between the support staff and the faculty since the burden on them is increased because of their frequent involvement in the design process. Majority of the student body seems to appreciate the hands on approach. But there is always a group or two that needs constant attention and help. It is also important to pick only those experiments, which can be completed within the time period- typically, the last three classes. In fact, during the initial phase of this experiment the access to laboratory at other than the scheduled hours was necessary. Finally, fine-tuning and improving the laboratory curriculum can easily accommodate the design or DEBTE concept. |
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