ME 322A: Mechanical Design and Machine Elements

Homework assignment 3 (10%): Concept generation, concept selection, needs-based screening and scoring

In this exercise, you will actually do some conceptual idea generation. You will then quantify some needs and use them in concept screening and scoring matrices.

Deliverables

  1. (50%) Create 8 concept sketches (2 on a single side of paper) for the following problem: Design a machine that makes varying length confetti from audio cassette tape. The confetti should vary in length from 2 to 10 centimeters. It is highly desirable if an operator of the machine can vary the length while the machine is running.
  1. (15%) We will complete a needs interview in class. You will begin with the data from this interview and you will produce quantified needs (i.e. “Happiness!!”) equations. (Therefore, you must come up with metrics.) Formulate one need related to manufacturability. The value for each need should vary between 0 and 1. These will become the rows of concept screening and scoring matrices. Actually create concept screening and scoring matrices for these designs. Screen your 8 concepts down to 3 using a 1 . . . 5 scale (perceived satisfaction of needs). Score (a weighted sum of Happiness equations which varies between 0 and 1) the survivors down to one winner.
  1. (25%) Create 4 concept sketches (2 on a single side of paper) for the design problem you have chosen.
  1. (10%) Since you have happiness equations and metrics already (from assignment 2), evaluate these happiness equations to score the designs down to one winner.

How not to get a bad grade:

  1. Make the drawings large enough and understandable. I must be able to see it, and get some idea of how it works, and how it might be made.
  1. The ideas should be good, and the ideas should be distinct.
  1. Use the interview as a starting point. Organize and distill what is said into quantified needs.

User Needs

Turns cassette tape into confetti. 5

Creates confetti immediately and continuously 4

Vary the confetti length while cutting. 4

Confetti length consistent while running 5

Smaller is better. 3

Both battery and human power. 3

One cut to tape to get started. 4

Has both spit and store modes. 3

Can store confetti in the device 3

Singulates stored confetti when spitting 2

Can spit the stored confetti 3

Processes 90 minutes of tape in 5 minutes. 3

Undesirable to disassemble tape case. 5

Can spit confetti 1 m. 2

Can do other tapes. 1

Listen to recording on tape. 0

Wastes less than 2 m of tape. 3

Portable 5

Easy to fabricate. 5