About Working with Flexible Assemblies

You can use a macromechanism to define an assembly as flexible during a dynamics simulation.

For the pistons of a motor to move independently, each piston assembly needs to be flexible. Each assembly (reference and instances) includes a mechanism with different command values.

Tip: If you create a mechanism under the reference of an assembly, then a mechanism appears automatically under each instance of the assembly.

To define an assembly as flexible, create a macromechanism under the parent assembly. From the Mechanical Systems Design section of the action bar, click Mechanism Manager to define the macromechanism.

In the Assembly tab, select the mechanism or mechanisms to assemble. The assemblies including the mechanisms referenced in the macromechanism are flexible.

In this example, the mechanism in a green frame is included in the macromechanism, under the Assembly node . The assembly including this mechanism is flexible.

If you instantiate a flexible assembly including engineering connections, then an Overloaded engineering connection is created under the Engineering Connections node of the assembly.

Update the mechanism to display the constraints of the flexible assembly as overloaded in the tree. For more information, see About Flexible Components in Assembly Design.

In the Mechanism Manager dialog box, select the overloaded constraints to include in the macromechanism. Each assembly is simulated as flexible.

Before simulating a model including a flexible assembly, specify the weight of every component. From the action bar, click Weight Definition to access the Weight Definition B.I. Essentials.

The weight of a component is defined by a mass, an inertia, and a center of gravity. You can either declare the weight of a component or compute it. For more information, see Displaying Weight Definition.

Important: Specify the inertia of every component that is not fixed or connected to a fixed component. If not, an error is displayed, specifying the name of the affected product or products. Specify the inertia to start the simulation.

During the simulation, if the instance of a flexible assembly is defined as repositionable, then its weight is subtracted from the weight of the subassembly.