SysML, SysML 2.0, UAF, UML, and UPDM Profiles > SysML2 Profile > System Behavior Modeling > Trade-off Analysis
Trade-off Analysis
A trade-off analysis is used to evaluate and compare alternatives. It is an analysis with the objective of selecting the optimum alternative from a given set based on an evaluation of each alternative. The TradeStudies domain library model provides a general framework for defining basic trade study analyses.
Creating a Trade-Off Analysis item
The first step in creating a Trade-Off Analysis item is to create a Standard Library Package. To create a Standard Library Package:
1. Create a Library Package. Right-click on the model or a package and select New > SysML2 > Library Package.
2. Select the Library Package and in the Properties section, in the Library Package tab, set the value of the IsStandard tag definition to TRUE.
Next, you must create a TradeStudy Analysis case. Perform the following steps to create a TradeStudy Analysis case:
1. Right-click on the Library Package which has been configured as the Standard Library package and select New > SysML 2 > Behavior Definitions > Analysis Definition. This creates an Analysis Definition.
2. Rename this Analysis Definition to TradeStudy.
Now, you can create the Trade-Off Analysis item in the diagram.
1. On the System Structure Diagram ribbon, in the Cases section, click the Trade-Off Analysis button.
2. Click on the empty space in the diagram to create the Trade-Off Analysis item.
A Trade-Off Analysis item is now created.
Parameters used in a Trade-Off Analysis item
A Trade-Off Analysis has the following parameters:
• Alternatives
• Objective
• Result
Alternatives
Alternatives are primarily Action usage items that are evaluated to find the optimum alternative based on the given Objective. Perform the following steps to add an Alternative to a Trade-Off Analysis item
1. In the Package browser, right-click on the Trade-Off Analysis item for which you want to add an Alternative and select New > SysML 2 > Behavior > Action. A new Action usage is now created.
2. Drag this Action usage from the Package browser and drop it on the Trade-Off Analysis item on the System Structure Diagram. A pop-up menu is displayed.
3. Select Add Alternative. An Alternative is now added to the Trade-Off Analysis.
You can add multiple Alternatives as required to the Trade-Off Analysis item.
Objective
An Objective is primarily a Requirement usage that determines the goal of the Trade-Off Analysis. Perform the following steps to set an Objective to the Trade-Off Analysis item
1. In the Package browser, right-click on the Trade-Off Analysis item for which you want to set the Objective and select New > SysML 2 > Requirements > Requirement. A new Requirement usage is now created.
2. Drag this Requirement usage from the Package browser and drop it on the Trade-Off Analysis item on the System Structure Diagram. A pop-up menu is displayed.
3. Select Set Objective. This sets the Objective for the selected Trade-Off Analysis.
Result
The result of the Trade-Off Analysis is an Action item with either the maximum or minimum evaluated value. Perform the following steps to set the Result for the Trade-Off Analysis
1. In the Package browser, right-click on the Trade-Off Analysis item for which you want to set the Result and select New > SysML 2 > Behavior > Action. A new Action usage is now created.
2. Drag this Action usage from the Package browser and drop it on the Trade-Off Analysis item on the System Structure Diagram. A pop-up menu is displayed.
3. Select Set Result. This sets the Result for the selected Trade-Off Analysis.
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