Classroom Card #3180
Through the lens of Entrepreneurial Mindset, multi-degree-of-freedom system is not just a model, but also a practical application.
Summary
Go beyond a theoretical model and identify a real-world application when EM is involved in Vibration.
Course
Fundamental of Vibrations is a junior-level course, mainly taught to mechanical and aerospace engineering students with a few exceptions to other engineering principles.
Time
Three weeks
Materials
The project is given after the completion of the multi-degree-of-freedom concept. Homework solutions on multi-degree-of-freedom system should be posted before the project is assigned.
Prerequisites
Differential Equations and Engineering Dynamics
Description
This is the second problem-based learning (PBL) design project with the entrepreneurially minded learning (EML) experience imbedded. Teams of three members are selected randomly to work on the project; and project grade for each student is assigned according to peer evaluations (Peer Review in Delivery folder).
The students are to design a dynamic vibration absorber (DVA) for a reciprocating engine using frequency spectrum as the primary guidance. The design is evaluated based on the responses of the engine and the absorber, and the practicality of the components - mass, spring, damper.
The project is done out-of-class and to be completed in three weeks. It is worth equivalently to seven homework sets. There are three check points in the project. At the first check point, the concept of single-degree-of-freedom (often referred to as SDOF) system that is the engine by itself, is reviewed: model, free-body diagram, steady-state response (Project Description in Delivery folder and Writing Template/Grading Rubric in Instructor Notes folder). At the second check point, the concept of multi-degree-of-freedom (often referred to as NDOF) system that is the engine with the DVA, is applied: model, free-body diagram, frequency spectrum (Writing Template/Grading Rubric in Instructor Notes folder). At this point, however, only mass and spring elements of the DVA are considered. At the final check point, the damping element for the DVA is selected (Writing Template/Grading Rubric in Instructor Notes folder).
The performance on the project can be found in ASEE SE 2023 paper [1].
Curiosity
- Demonstrate constant curiosity about our changing world
The students learn that vibration control applies to more than just machinery. It can apply to structure, in fact, to one of the tallest buildings in the world. Vibration control is a continuous art.
- Explore a contrarian view of accepted solution
The students learn that minimizing vibration is not always modifying suspension system, a commonly accepted solution of "reducing by subtracting (damping)." They find that "reducing by adding" is also a solution. A single-degree-of-freedom system can be converted into a two-degree-of-freedom so that its response can be controlled.
Connections
- Integrate information from many sources to gain insight
"Jigsaw" is the natural activity for teams that often come to the instructor's office hours. The MATLAB coding members from different teams share their findings during trouble shooting, and the absorber designers share the characteristics of their design without actually showing the designs.
- Assess and manage risk
The students learn how to assess and propose a solution to the problem while on the surface an infinite number of solutions seems to exist.
Creating Value
- Identify unexpected opportunities to create extraordinary value
The students search and find various combinations of spring, mass and damper to satisfy the functional requirement of an absorber. However, they have to use economic viability, customer value, technical feasibility, availability of components in addition to functional requirement to select one solution to the problem.
- Persist through and learn from failure
The students go through many trials and errors to find the "winning" design.
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