C.O. Smith
Engineering Consultant
1920 College Ave.
Terre Haute, IN 47803
G. Kardos
Department of Mechanical and Aerospace Engineering
Carleton University
Ottawa, Canada K1S 5B6
A difficulty in both ABET and CEAB accreditation procedures is providing sufficient "design" content in the curriculum, whether in courses in the curriculum or in "capstone" projects. ABET [1] says:
"Engineering design is the process of devising a system, component, or process to meet desired needs. It is a decision-making process (often iterative), in which the basic sciences and mathematics and engineering sciences are applied to convert resources optimally to meet a stated objective. Among the fundamental elements of the design process are the establishment of objectives and criteria, synthesis, analysis, construction, testing and evaluation. The engineering design component of a curriculum must include most of the following features: development of student creativity, use of open-ended problems, development and use of modern design theory and methodology, formulation of design problem statements and specifications, consideration of alternative solutions, feasibility considerations, production processes, concurrent engineering design, and detailed system descriptions. Further, it is essential to include a variety of realistic constraints such as economic factors, safety, reliability, aesthetics, ethics, and social impact."
The CEAB has a similar viewpoint. The question is how can this be done, especially in various engineering science courses. The skills necessary to carry out the design process can not be learned by listening to lectures but must be acquired by practice. Using engineering cases is one excellent way to provide a context for practicing these skills.
An engineering case is a written record of an engineering activity as the process actually progressed. A case documents a real engineering experience, usually from the viewpoint of one, or more, of the participants. In a well-written case, the student is presented with more than the bare facts of the problem to be solved. The case contains much of the auxiliary information, and establishes the context of the problem. The case may have such data as: sketches, drawings, photographs, calculations, test data, catalog data, scheduling requirements, budget information, production processes, field reports and other data that may influence trade-offs and decisions.
Cases are often written, or may be presented, in segments with each portion terminating at a critical decision point. This establishes a time sequence, providing information as it was acquired by the principals in the case.
Since cases are about real engineering activity, they offer an opportunity to raise questions and discuss solutions. Cases illustrate examples of good and bad engineering. They can show what happens to a well engineered project if communication with production breaks down. Because cases are real, they are independent of one engineering discipline, i.e. they involve several. Cases often show that, in pursuing technical objectives, questions of human behaviour and ethics may arise and seriously influence the outcome.
Since engineering cases represent real engineering activity, the judgements and decisions required of students can be critically compared by them and their peers with those made by the professionals in the case. From using cases, students discover that their decisions may be as good as those of the principal in the case, and perhaps better. Even when answers differ, exploring the nature of the difference and the underlying reasons can be a valuable experience. A case differs from a technical paper in that the case focuses on how results were obtained rather than on demonstrating validity of a solution.
The principal source of engineering cases is the ASEE Engineering Case Library [2, 18]. This collection of about 300 cases is a depository of a substantial amount of engineering experience. All cases in the library represent real engineering experience documented for the purpose of education. They are a ready and better context for illustrating and providing exercises on the application of engineering sciences in real engineering situations than textbook problems or fictitious scenarios.
"Teaching design in college means to impart to students the ability to apprehend the requirement of the customer, to select items of engineering, scientific, and mathematical knowledge which relate these requirements, and to unify all these into a feasible workpiece. This ability to unify is projective and synthetic. Analysis is preliminary to this ability and secondary." Freund [3]This can be done in any course by using cases. Smith and Kardos [4] have recommended cases to add design content to engineering science courses for accreditation purposes.
Cases should be considered as additional resources that can provide added dimensions to materials courses. They can demonstrate the importance of the principles being taught in solving the kind of real world problems students will be facing as engineers. Having students wrestling with problems in realistic contexts will produce new insights that can provide abundant and unanticipated rewards for students and instructor.
Engineering cases are a learning resource which can be used in many ways to develop the skills noted above and the capability implied by Freund. The authors have written extensively on ways to uses cases [4 - 16]. How and where engineering cases are used depends on course objectives, the nature of the class, and the style of the instructor. Experience has shown there is no specific right or wrong way to use cases. There are a variety of ways to use cases to bring reality into the classroom and enhance learning.
One of the best and most effective ways of using cases is in class discussions [5, 6]. Students are assigned a case, or a portion, to read. In some instances, questions are assigned to direct, or focus, student reading. In other instances, students are simply asked to read the case and be prepared to discuss what they find most interesting.
During the discussion, true understanding of the materials issues can be fostered by the instructor following Sparke's assertion: "Teaching consists of causing people to go into situations from which they can not escape except by thinking."
During case discussion, students are required to carry the discussion forward and explore facets of the case. Students define problems and issues, propose solutions and courses of action, and defend their points of view among their peers. Ideally, the instructor's role is confined to keeping the discussion on the topic, including exploration of pertinent tangents, and to ensure that meaningful learning is taking place.
In such discussions, students identify with the principals in the case and soon find themselves applying the principles learned in lectures and practicing the skills required in professional practice. Students are required to apply their engineering knowledge and background to the specific situation in the case. Use of engineering cases gives a focus and presence to class discussions that can not be achieved in any other way.
As detailed in the references, cases can also be used;
ECL-42 "Welded Joints/Hopper Trailer" (Table 1)
This case focuses on service failures in welded joints of hopper trailers which are pulled by large diesel trucks.
Comment: One enterprising professor gave this case to a class, took the students into the laboratory and showed them some steel plates in the corner [ which he had obtained fron the scrap yard ] . He told them the steel was from the hoppers which were failing. He further told them their task was to determine what was the cause of failure. He turned them loose in the laboratory to decide what tests should be made and to make them, to obtain the appropriate information to solve the problem. And finally to write a report on their findings and recommendations. This approach (a very successful one) provided far more interest and motivation than a "standard", or "routine" laboratory exercises.
The ASEE Engineering Case Library [2, 18] has some 300 cases with over ten percent having significant materials aspects, e.g., material selection, heat treatment, failure analysis, etc. These cases are listed in Table 1.
The November 1983 issue of Engineering Education (Vol. 74, No. 2) had a two page paper (Kardos, "Learning From the Problem of the Perverse Pinion," pp 92, 93) followed by ECL 135, "Problem of the Perverse Pinion" in its entirety (pp 94-98). This juxtaposition allowed the reader to see the case and how Kardos used it with a class of civil, electrical, and mechanical students in their junior year. Kardos' comments are highly representative of case use and student reaction. The authors strongly recommend you make the effort to find it in the literature and peruse it.
As noted, Table 1 lists the ASEE Engineering Cases which have substantial materials content. A sample of three is given below using the descriptions provided in the Case Catalog. A brief comment is also given for additional insight into the content of each case.
ECL 94 "Development of a New Drill Steel at Ingersoll-Rand Company"
Rock drills are used in mining, in excavating, and in other applications where it is necessary to remove hard rock. The drills produce holes into which blasting charges are later inserted. These holes may be as shallow as a few feet or as deep as one hundred feet. Depths of fifty feet are common. The holes are produced by a bit which is attached to one end of the drill rod. A pneumatic hammer hits the other end of the rod, through a so-called shank piece. The drill rods themselves, each about ten feet long and one and a half inches in diameter, are threaded at both ends and joined by couplings. This case study provides some background on the drilling process and the characteristics of existing drill rods, then traces the development of an improved drill rod.
Comment: The case shows the close relation between design, product performance, materials, manufacturing methods (including heat treatment), and capital equipment.
ECL 229 "The Aching Axle"
A left rear axle was found in a field following a highway accident involving three vehicles. The role of the axle in the accident is pursued with special emphasis on design and fabrication, including functional requirements, material selection, fabrication, heat treating, and quality control.
Comment: As indicated above, major emphasis is on functional requirements, axle configuration, material selection, and processing - factors which are inseparably related.
ECL 243 "The Bouncing Bottle"
A housewife is burned on both feet when a bottle of drain cleaner is accidentally knocked off a shelf and breaks, releasing its contents of sulphuric acid. A lawsuit is launched against the distributor, but what then?
Comment: This case focuses on selection of polymers, adequacy of testing, and use of sulphuric acid as a drain cleaner.
Engineering cases with principal focus on failure analysis, e.g., Ref. 15, provide opportunities to assess what went wrong but also to devise corrective action.
An instructor can (and is encouraged to) use cases based on;
We recommend the use of engineering cases for your benefit and the benefit of your students. It will provide an opportunity for a different kind of integration and stimulus to do engineering, and emphasizing materials. We are certain case use will enhance and add spice to the learning that will occur in your classroom.
Another way of using the case approach, which does not necessarily use "formal" engineering cases similar to those in the Engineering Case Library, is to use a series of problems, as if the student were to encounter them as an engineering consultant.
In this context, the class functions as a consulting firm serving small manufacturers having no in-house materials capability, allowing them to bid on various contracts and stay in business. The problem situation is given in the form of a letter of inquiry from a client company. The students (independently, or in small groups) are expected to define the problem, develop a feasible solution (usually including material selection, component geometry, forming, heat treatment, inspection, economics, etc.), and respond in the form of a letter (with sketches, as appropriate) to the inquirer.
This clearly can be viewed as a variation of engineering case use. It obviously requires students to operate in an open-ended situation with several possible solutions just as in professional practice. It also emphasizes communication skills, a very important ingredient of engineering practice.
Once the consultant organization is in being (by professorial fiat!), it might receive an inquiry such as given in Part 1 of Appendix I. If students correctly assesses the situation, they realize that the hardenability of AISI 1045 is too limited for the new, more demanding, application. An obvious solution is to recommend a steel with higher hardenability, e.g., AISI 4140, and to give the appropriate processing details. This clearly is an acceptable engineering solution.
When students submit their solutions (in letter form), it may be pedagogically profitable to have the class discuss the alternative solutions proposed. The discussion underlines the reality and acceptability of alternative (workable) solutions with an opportunity to judge relative merit. It also provides opportunity for verbal communication. Faculty comments can be made on the written communications before they are returned to the students.
Students are often surprised and somewhat disturbed to get another inquiry such as Part 2 of Appendix I. This second request is for a review of alloy choice and procedure, i.e., a rethinking of the situation, to see if there is a better way. Periodic review is, of course, an important aspect of good engineering practice.
Problems of this sort can come from many sources: personal experience, ASEE Engineering Cases, ASM International (and other) handbooks and publications. The Journal of Metals (June 1984 through March 1985) ran a series of Professional Examination questions which might be useful in this context. Appendix II gives some additional examples of useful consulting problems of varying degrees of difficulty.
Having used design projects, engineering cases, and consulting problems with a variety of students over a period of several years, there are some points which seem to recur regularly.
There is a strong tendency for students (and practicing professionals as well) to reshape a real problem, with all its various facets, into one with which they feel familiar. For example, using ECL 135, Perverse Pinion (cited in Part I), materials students usually emphasize the metallurgical processing aspects. While these are of interest and importance, the primary reason for failure arises from a severe notch and increased loading. Consider the following quotation from Almen [19].
"Fully 90 percent of all fatigue failures occurring in service or during laboratory and road tests are traceable to design and production defects and only the remaining 10 percent are primarily the responsibility of the metallurgist as defects in material, material specification, or heat treatment.
Study of fatigue of materials is the joint duty of metallurgical, engineering, and production departments. There is no definite line between mechanical and metallurgical factors that contribute to fatigue. This overlapping of responsibility is not sufficiently understood.
Hence, the engineers are constantly demanding new metallurgical miracles instead of correcting their own faults. Until metallurgists are less willing to look for metallurgical causes of fatigue and insist that equally competent examination for mechanical causes be made, we cannot hope to make full use of our engineering material."
[We should recognize that fatigue accounts for something like 85 percent of failures. Perhaps today, Almen's comment might be rewritten in terms of "materials" rather than "metals," but otherwise it is still as illuminating and pertinent as 50 years ago.]
Many students apparently fail to think through a given situation with the consequence of suggesting "solutions" which are physically impossible. In addition, many fail to make any assessment of the relative probabilities of alternative "solutions" proposed by that individual student (or team). Presumably both of these deficiencies will diminish as the individuals acquire added experience. It seems better, however, for the student to start this experience in academia rather than on first employment.
Some students quickly find the "free wheeling" style of using engineering cases and consulting problems to be highly enjoyable. Some arrive there later, and some never enjoy the looseness and flexibility of these open-ended solutions. One often finds some students with unimpressive grade averages who perform very well in this open situation which encourages creativity and synthesis. This is not really surprising: it is encouraging and reassuring.
There is a need for academia to try to simulate the reality of professional engineering practice. With too little information, one must make assumptions. With too much, or conflicting, information one must judiciously select the most appropriate. Nothing is more intellectually demanding than making decisions when you do not have complete information. Real engineering practice generates multiple solutions to a problem and selects the optimal one. The exercises discussed in this paper provide the kind of experience which moves students toward such professional practice.