1 © 2019 ANSYS, Inc.11

Workshop 06.1: Contact Offset Control

Introduction to ANSYS Mechanical

Release 2019 R3

2 © 2019 ANSYS, Inc.2

Goals• The model consist in the following assembly geometry with specified displacement

load.

• As the figure on the right shows, a 1.3161mm gap exists between the two parts.

• Our goal is to compare two approaches:− Solve the model as-is with no interface treatment.

− Solve the model using an appropriate initial contact offset to close the gap.

3 © 2019 ANSYS, Inc.3

Project SchematicBegin a new Workbench session and, from the Workbench window, choose “Restore Archive…,” browse to file “Contact_interface.wbpz,” and Open.

When prompted, save the project using the default name and the same location as the archive file.

From the “Units” menu, verify that:− Project units are set to “Metric (kg, mm, s, ºC, mA, N, mV).”

− “Display Values in Project Units” is checked.

4 © 2019 ANSYS, Inc.4

Project Schematic

1. From the Static Structural system, double-click (or RMB > Edit) the “Model” cell.

2. When Mechanical opens, verify that the units are set to “Metric (mm, kg, s, mV, mA).”

2.

1.

5 © 2019 ANSYS, Inc.5

PreprocessingVerify that the boundary conditions have been applied as follows:

• Fixed Support applied to the 2 holes in the body shown

• Remote displacement applied to the circular face shown: X = 0, Y = -10mm, Z = 0, RotX = free, RotY = 0, RotZ = 0.

6 © 2019 ANSYS, Inc.6

Preprocessing3. Expand the Connections and Contacts branches,

select the contact pair, and check the current contact settings:

• Notice the contact type is frictionless and that no offset has been specified in the form of an interface treatment.

• All other settings are at their defaults.

• Recall that a 1.3614 mm radial gap exists between the two pieces . With the boundary conditions as set, we should expect the model is initially unconstrained.

1.3161mm gap

3.

7 © 2019 ANSYS, Inc.7

Solution4. Solve the model.

• A quick check of the magnitude of total deformation should confirm the outcome.

• A magnified deformation shows the 2 parts have separated as expected.

4.

8 © 2019 ANSYS, Inc.8

Background

Background: How can we find the size of the gap?

One method is to select the circular lines for the two parts and request the “Selection Information.”

From the information panel, we can calculate the gap as 22 mm – 20.5 mm = 1.5 mm.

9 © 2019 ANSYS, Inc.9

BackgroundBackground: How can we find the size of the gap?

Another method is to insert a Contact Tool under the Connections branch and “Generate Initial Contact Results.”

The Initial Information table shows a gap of 1.3161 mm.

10 © 2019 ANSYS, Inc.10

PreprocessingTo address the gap, return to the contact region details:

5. In the “Offset” field enter 1.3614 mm. Verify the Interface Treatment is set to “Add Offset, Ramped effects”.

6. Solve the model again. The solution will require several iterations.

5.

6.

11 © 2019 ANSYS, Inc.11

Postprocessing7. The deformation and stress results now appear to be more reasonable.

Total Deformation Equivalent Stress

7.

12 © 2019 ANSYS, Inc.12

Postprocessing8. Insert a Contact Tool under the Solution branch and evaluate. Check the contact

Status result to verify that contact has been maintained.

8.

13 © 2019 ANSYS, Inc.13

Conclusions• The initial solution verified that the parts were separated by an initial gap.

• The gap size can be interrogated to collect some of the information needed to debug the contact problem.

• With the size verified, the gap can be closed effectively through the use of an initial offset.

14 © 2019 ANSYS, Inc.14

Go Further!If you find yourself with extra time, try the following:

1. Apply a body sizing to the two bodies and set a value of 10 mm

2. Also apply a face sizing to the faces in Contac and set a value of 8 mm

3. Change the configuration, change the Interface Treatment to “Adjust to Touch.” Is there a difference between this approach and adding an offset of 1.3614 mm?

15 © 2019 ANSYS, Inc.15

ENDWorkshop 06.1: Contact Offset Control