Mechanical Modeler

Objectives

The objectives of the Mechanical Modeler are multiple:

1. Provide an infrastructure for all the mechanical applications.

This infrastructure is the Part document and the set of interfaces to browse or create it. The article entitled "The Structure of a Part Document" [3] details the different containers of this V5 document and presents the links between them. One of which is the specification container. This container contains the mechanical features. There are three kinds of mechanical features:

• The Part feature: the main feature containing the design of the object to be built, and in particular geometrical features sets.
• The geometrical features sets: the features containing either other geometrical features sets, or geometrical features.
• The geometrical features: those which hold a topological result.

The "Contents of the Specification Container" article first details the Part feature [15], then the geometrical features sets [5], and finally the geometrical features [6]

2. Define the Specification/Result mechanism for the geometrical feature.

The Feature Modeler [1] is a Specification/Result Modeler in that it allows the creation of a network of inter-related data objects in order to be able to automatically update the "result" of an object whose "specification" has been modified. The Feature Modeler provides an infrastructure for Spec/Result management, also called the Build/Update mechanism.  The "Specification/Result Mechanism Applied to Mechanical Features" article [7] describes the internal view of the geometrical features in order to understand what is a mechanical result.

3. Enable having an associative geometrical result.

During the design, it can be useful to select an edge, or a face. These topological objects will be the inputs of a mechanical feature. But a feature cannot directly reference a topological object as specification. The main reason is that it can be deleted and rebuilt during an update. Consequently topological objects are unstable. The solution implemented in V5 to overcome this problem is to use a name instead of a direct reference to the topology. Such a name is called a generic name [8]. It provides a stable way to reference a topological cell.

4. Create new mechanical features.

In case the Part Design features or the Generative Shape Design features do not fit all your needs, you have the possibility to create your own mechanical feature by deriving from a mechanical StartUp [1]. The following articles can help you to follow all the necessary steps:

• "Creating a New StartUp Deriving from a Mechanical StartUp" [9]. This article describes from which Mechanical StartUp you should derive, and how to create the StartUp.
• "Integrating a New Mechanical Feature in V5" [10]. In deriving from a Mechanical StartUp, your feature automatically benefits from Mechanical behaviors that you do not have to redefine. But there is a set of interfaces which are to take into account for a full integration of the feature in the V5. This article presents the main V5 behaviors and gives the interfaces implied in these behaviors. They are classified by importance: the mandatory interfaces, the interfaces to be standard or the interfaces to implement only for specific cases. 
• "Integrating The New Geometrical Feature to the Update Mechanism" [11]. This article explains the CATIBuild interface implementation. 
• "Verifying the Validity of a Geometrical Feature"  [12]. For a new geometrical feature, the last step is the validation step. After the StartUp creation and the CATIBuild implementation, you should verify the feature modelization and check the result. The mechanical infrastructure provides a tool to realize this verification. This article describes how to use it and gives you some recommendations to correct errors if any.

Refer to the "Creating a new Geometrical Feature: The Combined Curve"  article for a concrete use case [13]. 

5. Provide Tools and Interfaces to interact with the Part document.

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Architecture

Frameworks

The Mechanical Modeler is based on several frameworks.

• MecModInterfaces / MechanicalModeler

These two frameworks provide interfaces and classes to manage the model of the mechanical applications.

• MechanicalCommands

This framework contains the interfaces to manage and create user features and power copies. They are "black box" features which are built on other mechanical features. The technical article entitled "An Overview of the Power Copies and User Features" [14] gives you details about these powerful features.

• MechanicalModerUI

This framework contains tools and interfaces to manage the user interface of the mechanical applications.

For example, the Part Design, Shape Design and Sketcher applications are based on these frameworks.

Scalability

The Mechanical Modeler offers several usage levels which are by increasing complexity order the following:

1. The first level enables you to consult the contents of a Part document in order to realize analysis or to do data transfers. A knowledge of the Part document and of the objects linked to the mechanical world is sufficient. [3][5][6].
2. The second level enables you to create your application by using supplied features, the Part Design and the Generative Shape Design features. 
3. The third level enables you to create new mechanical features from existing one. It is possible thanks to the Power Copy or the User feature mechanism. [14]
4. The fourth and last level enables you to create your own mechanical features. This advanced step requires to read the articles included in the "The Build/Update Protocol", "Accessing Sub-Elements" and "Creating a New Mechanical Feature" sections of the Mechanical Modeler home page.

The following picture summarizes the last three steps:

In most cases the Part Design and the Generative Shape Design features are sufficient for your applications. In the last level, you have always the possibility to create your own mechanical features, but it is rarely useful. The User features are an excellent compromise when the supplied features cannot fit your need.

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References

History

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