Information Technology Reference
In-Depth Information
S
E
V
S
E
V
O
C
C
O
C
C
D
E
T
D
E
T
R
P
N
R
P
N
FR, DP,or
Process
Step
FR, DP, or
Process
Step
Actions
Recommended
Actions
Recommended
Potential Failure Mode
Potential Failure Mode
Potential Failure Effects
Potential Failure Effects
Potential Causes
Potential Causes
Current Controls
Current Controls
How
severe?
10
What is the Effect
o
n the
(1)?
What
is the
priority
?
9
4
Follow
ups?
2
0
0
0
0
3
What can go
wrong?
7
0
0
0
0
5
What can be
done?
What are the
Causes?
How can this
be fo
und?
0
0
0
0
6
8
0
0
0
0
How Often?
1
0
0
0
0
What is the FR,
DP or Process
Step
FIGURE 16.4
SFMEA worksheet.
to rather extensive and complicated analyses, and second, the failure modes of the
function blocks are not known.
16.3.2 SFMEA Input
The IEC 60812
8
standard defines rather comprehensively the information needed
for the general FMEA procedure. It emphasizes the free availability of all relevant
information and the active cooperation of the designer. The main areas of information
in this standard are: system structure, system initiation, operation, control and main-
tenance, system environment, modeling, system boundary, definition of the system's
functional structure, representation of system structure, block diagrams, and failure
significance and compensating provisions (Haapanen et al., 2000).
A well-documented software-based system design mostly covers these items, so
it is more the question of the maturity of the design process than the specialties of
software-based system.
16.3.3
SFMEA Steps
The fundamentals of an FMEA inputs, regardless of its type, are depicted in
Figure 16.4 and in the list below:
1. Define scope, the software functional requirements and design parameters and
process steps: For the DFSS team, this input column easily can be extracted
from the functions and mappings discussed in Chapter 13. However, we suggest
doing the FMEA exercise for the revealed design hierarchy resulting from the
employment of mapping techniques of their choice. At this point, it may be
useful to revisit the project scope boundary as input to the FMEA of interest
8
IEC 60812 gives guidance on the definition of failure modes and contains two tables of examples of
typical failure modes. They are, however, largely rather general and/or concern mainly mechanical system
thus not giving much support for software FMEA.
Search WWH ::
Custom Search