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page 25

 

 

 

 

 

 

I

 

 

 

 

 

II

 

 

III

IV

 

 

 

 

 

 

Catastrophic

 

Critical

 

Marginal

Negligable

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A. Frequent

1

 

 

 

 

 

3

 

 

 

 

7

 

13

 

 

B. Probable

2

 

 

 

 

 

5

 

 

 

 

9

 

16

 

 

C. Occasional

4

 

 

 

 

 

6

 

 

 

 

11

 

18

 

 

D. Remote

8

 

 

 

 

 

10

 

 

14

 

19

 

 

E. Improbable

12

 

 

 

15

 

 

17

 

20

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Risk Index

 

 

Criterion

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1-5

 

 

 

 

 

unaceptable

 

 

 

 

 

 

 

 

 

6-9

 

 

 

 

 

undesirable

 

 

 

 

 

 

 

 

 

10-17

 

 

 

acceptable with review

 

 

 

 

 

 

 

18-20

 

 

 

acceptable with no review

 

 

 

 

 

 

Category

 

Description

 

 

Definition

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I

 

 

 

 

catastrophic

 

 

death or equipment loss

 

 

 

 

 

 

II

 

 

 

 

critical

 

 

 

major injury, illness or system failure

 

 

 

 

III

 

 

 

 

marginal

 

 

 

minor injury, illness or system failure

 

 

 

 

IV

 

 

 

 

negligable

 

 

 

insignificant loss of function

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Level

 

Description

 

 

Single Item

 

 

 

 

 

 

 

Inventory

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A

 

frequent

 

 

 

happens often

 

 

 

 

allways happening

B

 

probable

 

 

 

occurs several times over life of product

occurs frequently

C

 

occasional

 

 

 

will occur sometime over life of product

occurs several times

D

 

remote

 

 

 

may occur during life of product

not often

E

 

improbable

 

 

rarely occurs

 

 

 

 

 

 

 

rarely

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DI:8.3 HUMAN STRENGTH AND PROPORTIONS

• When designing we can use statistical values of human proportions to set sizes of components, forces, etc.

page 26

• These tables are available from a number of sources such as NASA. There is a set of tables in the back of the text book.

DI:8.4 EQUIPMENT INTERFACES

When a human interacts with a machine they use controls to begin actions, and displays to monitor status.

Typical controls include,

-switches (push, toggle, touch, etc.)

-sliders, knobs

-

Typical displays include

-indicator lights

-audible tones (buzzers, beeps, bells, etc.)

8.5 REFERENCES

Ullman, D.G., The Mechanical Design Process, McGraw-Hill, 1997.