...
The following table lists the relationships that are relevant in multiple types of documents/diagrams and their meanings within a certain document/diagram type:
Relationship | Usage in Document | ||||
|---|---|---|---|---|---|
SysML Diagram | FMEA Document | RE Document | FMEDA Document | FTA Document | |
Hierarchy of system elements | Composition | Hierarchy of system elements | Hierarchy of modules | Hierarchy of modules | - |
Assignment of functions to system elements | Allocate relationships | Assignment of functions to system elements | - | Assignment of hardware function to module | - |
Assignment of malfunctions to functions | Composition | Malfunction | - | Assignment of hardware failure to hardware function | - |
Assignment of safety goals to functions | Satisfy relationship | Assignment of safety goals to functions | - | Safety goal | - |
Assignment of requirements to any other object | Satisfy relationship | - | - | - | - |
Terminological aspects:
Association: specifies peer-to-peer relationships between model elements, e.g. if a Class-x has an attribute of type Class-y, it can be viewed in a class diagram as an association between Class-x and Class-y.
Aggregation: is used to model a whole/part relationship between model elements. The part element can exist without the whole. Aggregation causes the generated code to contain the aggregate either by reference or by value, depending on the details of the relationship. E.g. to model an aggregation, the aggregate (Department) has an aggregation association to its constituent parts (Employee). A hollow diamond is attached to the end of an association path on the side of the aggregate (the whole) to indicate aggregation.
Composition: is an aggregation with strong ownership, i.e. if the container is deleted, all of its composite
objects are deleted as well.Generalization: relationship causes a class to be generated as a subclass of another class.
Realizes: relationship specifies that, e.g. an implementation realizes a specification. The Realizes relationship does not affect the code.
...