Document Type

Conference Proceeding

Language

eng

Publication Date

6-15-2014

Publisher

American Society for Engineering Education

Source Publication

2014 ASEE Annual Conference & Exposition

Source ISSN

2153-5965

Abstract

Helicopters as a Theme in Teaching Machine Design A machine design course is required in most undergraduate mechanical engineering curricula. This course generally covers an introduction to mechanical engineering design, a review of materials engineering, a review of mechanics of materials (shear force and bending moment diagrams, stress and strain analysis, deflection and stiffness analysis of beams, columns, etc.),models for failure due to static loading and variable fatigue, and then presents (in somewhat arbitrary order) the design of specific mechanical elements: shafts, fasteners, springs, bearings, gears, flexible elements such as belts, chain, and wire rope, clutches, brakes, couplings, etc. For some topics in machine design it is not possible to develop analytical models from first principles, as is done in fluid mechanics or thermodynamics. Rather, there are guidelines and "rules of thumb" and "equations" that include "factors" that must be taken on blind faith and somehow used to get an approximate answer. The approach can be unsatisfying, arbitrary, and not meaningful unless it is tied to real-world problems. To help motivate student learning, foster interest in the topics, and make the material more alive, we are testing the idea of studying helicopters and their components throughout the course as a theme to teach students about the different mechanical elements. Helicopters are an ideal system to exemplify the concepts taught in the course because all aspects of machine design are encapsulated in the design of a helicopter and the price of failure of the components or design is high (human fatality). In the standard helicopter configuration, two turbine jet engines are used to drive a main rotor and a tail rotor and the pilot controls are mechanically linked to both rotors to allow for handling of the aircraft. For each topic in the course the connection to helicopters is presented and helicopter design challenges are posed. For example, the shafts and gearboxes used to transfer energy from the high-speed turbine engines to the low speed rotors can be used to teach students about shaft bending, gear design, and fatigue failure. When asked to design a gearbox to achieve the speed reduction between the turbine jet engine and the main rotor, students discover why planetary gears are used. Other topics such as clutches, brakes, couplings, fasteners, springs, and vibration effects are all prominent features of helicopter design. They serve as excellent motivating examples to show students the real-life applications of machine design concepts. In closing, students generally view the machine design course as very challenging and, due to the many specific machine elements covered, have difficulty seeing how the separate components fit within the needs for a real system. To address this concern, enhance learning, and bring more excitement to the topics, we explored the value of using a theme physical system, namely helicopters and their components, to bring the material to life when teaching machine design.

Comments

Published version. Published as a part of 2014 ASEE Annual Conference & Exposition, Indianapolis, Indiana. June 15-18, 2014. Permalink. © 2014 American Society for Engineering Education. Used with permission.

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