First In Engineering: Elements Of Mechanical Design

Abstract

The role of design in engineering education and the teaching of design has changed over the past several decades. In the specific case of mechanical design, increasing emphasis has been placed on mechanical analysis rather than on design methodology. This can be seen in the dominance of mechanical analysis in mechanical design or machine design textbooks and the relatively light (or non-existent) treatment of how to make design decisions. The reasons for this trend have been described in Suh's Principles of Design 1 and Hazelrigg's Introduction to Systems Engineering 2 , among others. There has been a growing trend to reexamine what skills are taught in a design class. This trend is driven primarily by industry's need for project management and design decisionmaking skills, in addition to analytical skills. 3 Another skill set which has been disappearing is design by analogy. Emphasis is placed on developing novelty in design (the "new and different"). In fact, a "new and different" design requires complete validation, which is more expensive than modifying an existing design to achieve new objectives. The costs of validation and reduction to practice must be considered in the decision to develop a new design versus modifying an existing design. With the development of optimization methods and more powerful analytical tools, many engineering students suffer under the illusion that, with enough mathematics and computing power, the design process requires only that constraints be established, and a computer will compute the answer. However, design is a synthesis process, and it is not possible to calculate a unique design. In general, the constraints are never fully known, and they change over time. The designer must develop a skill set to evolve through the infinities of solutions to synthesize one out of many successful configurations. Since design is a creative process, it is very similar to the process of music composition. The composer must first learn the standard musical forms. He then combines those forms with his creativity to synthesize a novel composition. The design equivalents to musical forms are the elements of design. A first design course should introduce these elements and demonstrate the "process of composition." The analysis of the design should come later. This is not to say that analysis and engineering science are bad things. In the modern world of developing technology, new technologies can only be created through the combination