Failure Diagrams

A Failure Diagram describes the physical processes of a failure of a model item

which affects its functional failure mode. Failure Diagrams detail physical failures of

Parts, Pairs and Components. This is achieved by defining five types of failure

concepts:

• Causes
• Mechanisms
• Faults
• Symptoms
• Functional Failure Modes

Failure concepts are connected in specific order with one another using causal

connections.

Failure concepts representing physical failures should be modelled from Part-level

which is then connected to the Pair & Component failure modes. If this level of

granularity is not required or cannot be achieved (e.g a failure occurring when two

parts interact within the context of a pair) mechanisms and faults can be inserted

directly into the pair failure diagram. Failure concepts can also be added to a

component failure diagram, however this practice is not encouraged as it does not

provide sufficient clarity to the origins of failure.

Failure diagram editors for Parts, Part-pairs and Components are accessed in the

same manner, however there are several visual differences in how information is

displayed. The example below looks at the Fuel Tank component in the Vehicle System.

The Fuel Tank contains the parts "Inlet", "Lining" and

"Outlet".

[Image: failureproject.png]

Part Failure Diagram

This is the lowest level that has Failure diagram access. This level intends to

model physical failures of the part originating from a cause through to a part fault.

[Image: partfailurediagram.png]

Part-pair Failure Diagram

The Part-pair Failure Diagram describes faults that only occur when two Parts work

together and impact on the functionality of the pair. This editor also allows the user

to define how Part failure concepts contribute to a part-pair failure mode. Parts in

this editor are represented by a grey rectangle which can be expanded and collapsed to

show part failure concepts.

To open the part-pair failure diagram & access part failure concepts:

1. Right-click a pair connection in the system model
2. Select "Failure Diagram" from the menu
3. In the Failure Diagram editor select the "Expand" or "Collapse" button on the grey rectangle [Image: expand-innerDiagram.jpg] [Image: colapse-innerDiagram.jpg]

[Image: pairfailurediagram.png]

Component Failure Diagrams

Component Failure Diagrams provide similar functionality to Pair Failure Diagram in

that it allows Causal modelling (Part-pairs failure mode connected to component failure

mode). The user can view Part-pair and Part failure Diagrams by expanding their

respective grey rectangles.

[Image: componentfailurediagram.png]

Complex failure diagram scenarios that can be captured in this editor include:

• Induced Causes within a Pair Failure Diagram.
• Creating a pair connection between a Part and Component to create a multi-indentured Failure Diagram.
• Filtering of Failure Concepts in a Report output.
• Blocking Causal Impacts on Induced Causes.

See also: Failure Diagrams in the MADE Module

Manual.