About Contacts

Contact Engineering Connections are used to avoid clashes between two groups of products during a kinematic or a kynamic simulation, or to model contact behaviors. Any component at any level of the active product, except hidden 3DParts, can be selected to generate contacts.

Two contact models can be used during a kinematic or a dynamic simulation: the Surfacic Contact Model and the Restitution Contact Model. For more information, see About the Surfacic Contact Model and About the Restitution Contact Model.

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About Integrators

Meshing Properties

You can manage the accuracy of the mesh in the 3D area by accessing theCommon Preferences of the 3DEXPERIENCE Platform. It is recommended to use the default Fixed option and enter a SAG value adapted to your objective (visual quality of the mesh or simulation performance).

For more information, see Meshing Properties.

Contact Specifications

In a simulation, contacts are generated between two groups of products, Group1 and Group2. The simulation determines if any element from Group1 enters in contact with any element from Group2.

To manage contacts, click Contact Connection from the Mechanical Systems Design section of the action bar. For more information, see Managing Contacts.

To obtain a more accurate simulation, elements from Group1 should have a better tessellation than the elements from Group2.

Before computing a kinematics or a dynamics simulation, make sure that the initial state is valid:

  • No clash detected on a product.
  • All constraints are satisfied.
  • All position motors are satisfied.
  • All position law excitations are satisfied.

Contacts are managed in two steps: the collision detection and the contact reaction.

Contacts During a Kinematic Simulation

During a kinematics simulation, the solver measures the displacement of objects. The forces applied are not taken into account. When a contact is detected, the solver modifies the position of the two element groups specified in the Contact Engineering Connections to prevent a clash.

The solver guarantees that the contact (orange arrow in the figure) does not exceed the sum of the chordal deviation (SAG) of each group (blue arrows in the figure).

The force-related behaviors set in the Restitution and Surfacic Contact Model parameters are not taken into account by the solver. To obtain a more realistic behavior, you can add constraints.

To prevent a tunneling effect during the simulation, the simulation step must be smaller than the size of the objects.

Contacts During a Dynamic Simulation

During a dynamics simulation, the solver measures the force applied to objects, including inertia and frictions. When a contact is detected, the mechanism is expected to behave in a realistic way. To do so, physical parameters are set for the products listed in Group1 and Group2.

During a dynamic simulation using the DASSL integrator, if a motor drives the command of a mechanism along a given direction and if a contact opposing this direction is detected between this product and another, the contact is not taken into consideration.

For more information, see About the DASSL Integrator.