# A Beginner’s Guide to Understanding ANSYS Contact Types

Choosing the right contact type for your ANSYS simulation can be a daunting task, especially for new users. With options like Frictionless, Rough, Frictional, and No Separation, it’s easy to get confused. In this article, we’ll explain each type of contact and provide helpful illustrations to guide you through the process.

### 1. Bonde

The Bonded contact type is the default configuration and applies to all contact regions (surfaces, solids, lines, faces, edges). This type of contact behaves as if the regions are glued together, with no sliding or separation between faces or edges allowed. Since the contact length/area remains constant during load application, a linear solution is possible. Gaps and initial penetrations are ignored if they exist in the mathematical model. Note that this contact type is not supported for Rigid Dynamics, but Fixed joint can be used instead.

### No Separation

No Separation contact type ties up the target and contact surface for the rest of the analysis once contact is detected. Sliding is possible, but nodes in contact are bonded to the target surface in the normal direction.

### Frictionless

The Frictionless contact type models standard unilateral contact where normal pressure is zero if separation occurs, allowing gaps to form between bodies depending on loading. This type of contact is nonlinear since the contact area may change as load is applied. A zero coefficient of friction is assumed, allowing free sliding, but the model must be well-constrained. Weak springs are added to stabilize the model and achieve a reasonable solution.

### Frictional

The Frictional contact type allows the two contacting geometries to carry shear stresses up to a certain magnitude across their interface before they start sliding relative to each other. This is known as “sticking.” The model defines an equivalent shear stress at which sliding begins as a fraction of the contact pressure. Once the shear stress is exceeded, sliding occurs. The coefficient of friction can be any non-negative value. Note that this contact type is not supported for Rigid Dynamics, but Forced Frictional Sliding should be used instead.

### Rough

The Rough contact type models perfectly rough frictional contact where there is no sliding, similar to the Frictionless type. It applies only to regions of faces (for 3D solids) or edges (for 2D plates). By default, no automatic closing of gaps is performed, and this corresponds to an infinite friction coefficient between the contacting bodies. Note that this contact type is not supported for Explicit Dynamics analyses.

In conclusion, selecting the appropriate contact type in ANSYS depends on the specific problem you are trying to solve. By understanding the characteristics of each contact type, you can choose the best one for your simulation and achieve accurate results.

Good Luck!