Wear

Add a subnode to model mechanical wear created when the contacting surfaces are sliding along each other. Typically, the wear rate is a function of the contact pressure and the slip velocity.

The selection of the node is the same as that of its parent node. If significant wear can be expected on both surfaces in a contact pair, you can add two nodes.

As wear involves a rate equation, it is only possible to compute wear a in time-dependent study. For other study types, the node is ignored.

The node is only available with some COMSOL products (see https://www.comsol.com/products/specifications/).

Wear Model

Select a — or . When is selected, the geometry of the domain is actually changed, and a set of extra degrees of freedom are added to the model. For the formulation, the computed wear depth hwear is added as an offset to the contact condition.

Select a — or .

For , enter a , kwear, a , Tn,ref, and an , n. The wear rate is defined as

Here, Tn is the contact pressure, and vslip is the slip velocity. For a classical Archard equation, n = 1. The reference contact pressure, Tn,ref, can be chosen arbitrarily, and is used only to obtain consistent units. In most cases, Tn,ref, should be chosen as the unit pressure in the current unit system, for example 1 Pa.

For , enter an expression for the general source term, f, which defines the wear rate. The default is an expression similar to
(1e-9[m^2/N]*solid.cnt1.wear1.Tn)*solid.cnt1.wear1.vslipnorm.
This expression provides the names of the local variables for contact pressure and slip velocity, inserted in a classic Archard equation.

Finally, select a — or . If both surfaces in the contact pair are subject to wear, add two separate nodes.

•

In general, modeling wear on the destination side is slightly more accurate, since it is there that the contact pressure and slip velocity are originally computed.

•

It is possible to use the Rigid Domain material model on the source side.


	If the model was originally created in version 5.2 or earlier, you must enable the possibility to use deformed geometry manually. Go to the settings for the Component, and click the Permanently Define All Frames button. See also The Component Node.

Advanced

This section is only available when is set to .

Choose how to set the — or . When is selected, the deforming domains are assumed to be all domains adjacent to the destination or source boundaries, as selected by . This is the default. By selecting , a new section, , is displayed. There, you can make a manual selection of the domains to act as deforming.

In order for the mesh smoothing in the deforming domain to work properly, the mesh on all exterior boundaries, except the wear surface, should be free to slide in the tangential directions. Choose how to set the — or . When is selected, a sliding boundary condition added to all exterior boundaries of the deforming domain, expect the wear surface. This is the default. By selecting , a new section, , is displayed. There, you can make a manual selection of the sliding boundaries. The selection on which wear is applied is always excluded.

The remaining settings in the section affect the detailed mathematical model used for remapping the mesh in the deforming domain. For details, see Deforming Domain.


	In most cases, the Automatic option will set up an appropriate Deforming domain selection and a corresponding Sliding boundary selection. For complex geometries it might, however, be necessary to manually control these selections. In case the automatic selections are incorrect, it is often displayed as an error from the solver, or clearly visible in the results of the exterior edges of the wear surface.