Part 4 - Design for Reliability and Safety

Question 1

Single Point Failure

Answer 1

Single Failure Leads to Catastrophic Failure

Question 2

Common mode failure

Answer 2

Single effect causes several sub systems to fail

Question 3

Cascade Failure

Answer 3

One failure leads to another

Question 4

Fault intolerant system

Answer 4

Single failure causes system to fail (chain)

Question 5

Fail Safe

Answer 5

Fail in a non catastrophic way

Question 6

Safe Life

Answer 6

Period of safe operation

Question 7

Stages of Reliability Modelling

Answer 7

Identify Components 
Calculate reliability of each component.
Formulate Block Diagram
Calculate Reliability 
Identify areas of low reliability 
Devise method to improve reliability

Question 8

Examples of Fail-safe design

Answer 8

Fuse trip when overheating. Circuit breakers
Ductile failure in bike rim prevents catastrophic failure
Modern cars have twin hydraulic bikes

Question 9

Measures to reduce failure

Answer 9

Evaluate severity against likelihood of occurrence. Devise mitigation plan

Question 10

What is Fault Tree Analysis

Answer 10

Model / Record how a failure can occur based on a series of events. Can be combined as AND boxes or OR boxes. Used to understand / predict failures