If your assembly contains a few part instances that are unrelated, dependent instances have little advantage over independent instances. Each part is different, and you must create an instance of each part. In contrast, if your assembly contains identical part instances, you can save time by assembling dependent instances of the part. When you subsequently mesh the original part, Abaqus/CAE applies that mesh to each dependent instance of the part in the assembly. In addition, dependent instances consume fewer memory resources and result in a smaller input file.

For example, Figure 13–2 illustrates an assembly of independent and dependent part instances. The pump housing is an independent part instance, and the eight bolts are dependent part instances. The figure on the left shows the assembly in the Assembly module. The figure on the right shows the assembly in the Mesh module. The user has meshed the part representing the bolt, and Abaqus/CAE associated the mesh with each dependent instance of the bolt.

You will find it more convenient to use dependent part instances when you use the linear or radial pattern tool to create a pattern of identical instances. When you mesh the original part, Abaqus/CAE applies the same mesh to each dependent instance in the pattern. In contrast, if you create a pattern of independent instances, you must mesh each instance individually.

Abaqus/CAE creates dependent instances by default. Unless your assembly contains only a few parts, it is recommended that you work with dependent instances because of the memory savings and the resulting performance gain.