Welcome W 6.2 Introduction to Engineering Design II (IE 202) Chapter 4: Functions and Objectives 1 1

Today’s Learning Outcomes By the completion of today's meeting, students should be able to: identify function. express functions. analyze functions. 2 2

What is the next step? What have we covered so far? Overall design process Project management Problem definition 3 3

2nd Task in the Design Process 4 4

Identifying Functions Mathematical Functions are: specifying how some set of inputs is transformed into a set of outputs. Engineering Functions: are concerned with the transformation or transfer of energy, materials and information between input and output. Techniques to identify and specify Functions are: black boxes and transparent boxes dissection and reverse engineering function-means tree 5 5

The Black Box Approach What does a black box mean to you? A black boxes is a graphic representation of the system or object being designed, with inputs shown entering the box from one side and outputs leaving on the other side, without knowing what the system is. INPUT System? OUTPUT 6 6

Consider the power drill. Example on the Black Box Consider the power drill. Work in your team to specify the inputs and outputs. When asked come and present your black box approach. 7 7

The Power Drill Black Box There are three inputs: a source of electric power, a supporting force that holds or grasps the drill, and the control speed and direction of the drill chuck’s rotation. The output is a hole in the wall. 8 8

Example on the Transparent Box Consider the power drill, again. 9 9

The Transparent Box Example After drawing the black box indicating the system boundary, all the inputs and outputs are shown going into or coming out of the systems. The cover of the box is then “removed”, and the designer can focus attention on how the various inputs are transformed. This process can be repeated iteratively until the designer is satisfied that he can develop a suitable means of realizing the functions. 10 10

Dissection and Reverse Eng. The designer can often find an artifact that performs some or all aspects of the basic function. The artifact can then be examined with the question, “what does this do?” being asked of all the components of the artifact. 11 11

Example on Dissection Exploded view of the major subsystems in corded power drill. 12 12

Functions and Means Functions and Means Means are methods of achieving functions, and they imply solutions. Examine the power drill. Can you identify any means? 13 13

Functions-Means Tree For each function, several means of accomplishing the function are listed, and then the subsidiary functions that result from that are listed below the means. This continues until the designer is satisfied that all the functions have been developed. 14 14

Activity The primary function of a cigarette lighter is to ignite leafy material. Identify means for a cigarette lighter. Identify sub-functions for one of the means. Identify means for each of those sub- functions, within your team. 15 15

Functions-Means Tree Ex. Consider a cigarette lighter. 16 16

Functions and Objectives Functions describe what artifacts do, while objectives tend to characterize what artifacts are. Can you come up with some functions of the mobile phone and some objectives. 17 17

Functions and Objectives’ Functions describe what objects will do, with particular focus on the input/output transformations. Functions transform inputs to outputs, active verbs. Objectives describe what the designed device will look like, i.e. what the final object will be and what qualities it will have. Objectives detail attributes, linking verbs. 18 18

In-Class Assignment # 3 – ZX TX MX This is an in-class assignment to be solved individually. The answer should be submitted electronically. The file name for your work when submitted should be: In-Class Assignment # 3 – ZX TX MX You have to change X for your case. 19 19