The relationship of parts (part), Entity (Instance) and set (Assembly) in the Abaqus __assembly

1. Relationship of Parts (part), Entity (Instance) and set (Assembly) (13.3.1)

A model can include many parts (part), but it can contain only one set (Assembly). This collection is composed of many entities (Instance), and these entities (Instance) are formed by parts (part) that are specified in the overall coordinate system. For example, if a part is a brick, then the bricks can form a wall, the wall is equivalent to a solid (Instance), many walls can form a house, the house is equivalent to a collection (Assembly), these entities can form a set.

The concepts of parts, entities, and collections are always throughout the ABAQUS/CAE modeling process.

1 Create a part in part module, each part is independent, and its modification and operation are independent of other parts. Parts exist in their own coordinate systems and are not related to other parts.

2 The concept of defining section attributes in the property module is for the section and material to be connected, or for assigning these section properties to a selected area of the part or part in the property module.

3 You can create entities (Instance) for parts in the collection module (Assembly module), and you can specify the positions of these entities relative to the overall coordinate system to form a collection (Assembly). Abaqus/cae (Dependent) part entities and independent (independent) part entities can be created in the. Whether it is a stand-alone part entity or a non-standalone part entity, it is connected to the original part. When you modify the original part in a part module, the Assembly module (Assembly module) abaqus/cae automatically updates all the entities of that part when it is returned. You can also create multiple entities (Instance) for a part, and set up several entities (Instance) for one part of the contract. Each entity of a part has the section properties that are specified in the Attribute module (property module) for the part.

4 The model can be completed using the Interaction Module (interaction module) and the load modules (load module). For example, define contact relationships and apply loads, boundary conditions. Interaction Modules (interaction module) and load modules (load module) are sets of operations (Assembly), not parts (part).

5 the grid partition module (mesh module) can be used to divide the set (Assembly). There are two ways in which each independent entity (independent instance) of a part in the set (Assembly) can be partitioned independently of the grid, that is, the grid is divided into entities (instance), the original parts are divided, That is, the grid is partitioned directly on the parts of each dependent entity (Dependent instance) in the set (Assembly), and the grid is divided into parts (part).

2. Distinction between independent entities (independent instance) and non-independent entities (Dependent instance)

When creating a part entity, you can choose whether to create a separate entity (independent instance) or a dependent entity (Dependent instance). You can also edit an entity and convert a stand-alone entity to a dependent entity, and you can also convert a dependent entity into a stand-alone entity. The following is a specific description of the concepts of non-independent entities and independent entities:

1) Non-independent entities (Dependent instance)

By default, Abaqus/cae creates a dependent entity for the part. A dependent entity is just a pointer to the original part. In fact, a non independent entity and the original part share geometry and grids. Therefore, you can divide the original parts into grids, but you cannot partition a mesh on a dependent entity, that is, the mesh on part. When the original part is divided into grids, Abaqus/cae will apply the same grid to all the dependent entities of the part. Most modifications will not be modified on a stand-alone entity, for example, you cannot add partitions or create a virtual topology. If a part has been partitioned or a virtual topology has been added to the part, you can create only one independent entity for that part.

If the grid partition of a discrete entity part is specified in a grid module as an adaptive grid partition, Abaqus/cae the original part and applies the new mesh to each dependent entity of the part.

For each dependent entity (generated by the same part), the properties of the grid cannot be changed because their grid is the part's grid. These grid properties include grid seed, grid control, cell type, and the grid itself. However, the grid properties of the original part can be abaqus/cae, and the modified changes are then transmitted to each of the dependent entities corresponding to the part.

The advantage of a non-independent entity is that it can save a lot of memory resources, and the grid partitioning of the parts only needs to be done once.

2) Independent entity (independent instance)

In contrast, a stand-alone entity (independent instance) is a replicated object of the geometric model of the original part. Its relationship with the original part simply copies the geometry of the original part. After you create a standalone entity, you cannot mesh the parts, but you can partition the separate entity. In addition to grid partitioning of independent entities, you can perform most operations on independent entities, such as adding partitions and creating virtual topologies. But the disadvantage of a stand-alone entity is that it takes up more memory resources and meshes with each individual entity.

For the same part, you cannot create both a separate entity and a stand-alone entity, either by creating a stand-alone entity or by creating a non-independent entity. Finally, if you create a separate entity for a part, the entities that you create later with that part are non-independent entities, as is the case for independent entities.

3. How to determine whether to choose to create an independent entity or a non-independent entity

If the collection (Assembly) contains some part entities that are not related to each other, it is advantageous to choose to create independent entities. Because each part is different, you must create an entity for each part. In contrast, if a collection contains many of the same part entities, you can save time by using a set of dependent entities. You only need to divide the grid for a single part, and the grid of all the dependent entities associated with it is already available.

Specifically, if the collection contains many parts of the same nature, create a non-independent entity. Conversely, if a collection contains many parts of a different nature, it is advantageous to create a standalone entity.