Creating a VCCT crack for Abaqus/Standard

You can create a virtual crack closure technique (VCCT) crack that can be analyzed by Abaqus/Standard by doing the following:

  • Create a contact interaction property that specifies the fracture criterion. The fracture criterion interaction property specifies the criterion for crack propagation along initially partially bonded surfaces. You can choose between the following crack propagation criteria:

    • The virtual crack closure technique (VCCT) criterion, which uses the principles of linear elastic fracture mechanics. For more information, see VCCT criterion.

    • The enhanced virtual crack closure technique (Enhanced VCCT) criterion, in which you can control the onset and growth of a crack using two different critical fracture energy release rates. The enhanced virtual crack closure technique is available only in an Abaqus/Standard analysis. For more information, see Enhanced VCCT criterion.

  • Create a surface-to-surface contact interaction that models the potential crack surfaces using master and slave contact surfaces. The initially bonded region defines a region of the slave surface that is initially bonded with the master surface. The unbonded portion of the slave surface behaves as a regular contact surface. For detailed information, see Defining initially bonded crack surfaces in Abaqus/Standard.

  • Activate the crack propagation capability to specify that crack propagation can occur between the two surfaces that are initially partially bonded. The crack continues to propagate along the interface between the master and slave surfaces. The virtual crack closure technique cannot model crack initiation from a surface that is not already cracked; therefore, you must specify a clearance between the slave and master surfaces that models a preexisting flaw at the beginning of the crack surface.

    For more information, see Crack propagation analysis.

Related Topics
Fracture mechanics
In Other Guides
Crack propagation analysis

  1. Create a contact interaction property that defines the mechanical fracture criterion, as described in Specifying fracture criterion properties for crack propagation.

    1. Choose the crack propagation criteria (VCCT or Enhanced VCCT).

      Note:

      The Direction of crack growth relative to 1–direction option applies only to enriched regions that will be used by the extended finite element method (XFEM) for crack propagation.

    2. Specify the critical energy release rates for crack onset and propagation.

  2. Create a surface-to-surface contact interaction that specifies the master and slave surfaces (the region that contains the potential crack surfaces), as described in Defining surface-to-surface contact in an Abaqus/Standard analysis.

    1. Select a discretization method of Surface to surface.
    2. From the Bonding tabbed page, toggle on Limit bonding to slave nodes in subset, and choose the set that specifies the initially bonded nodes of the slave surface. The unbonded portion of the slave surface behaves as a regular contact surface.
    3. Select the contact interaction property that defines the mechanical fracture criterion.

  3. Activate the VCCT crack propagation capability.

    1. From the Interaction module main menu, select SpecialCrackCreate.
    2. From the Create Crack dialog box that appears, select Debond using VCCT.
    3. Enter the name of the crack, and click Continue to close the dialog box.

      The Edit Crack dialog box appears.

    4. From the Edit Crack dialog box, do the following:

      1. Select the step in which the crack propagation is initiated.

      2. Select the surface-to-surface contact interaction that specifies the master and slave surfaces.

      3. Specify how the traction between the surfaces defined in the contact pair interaction is released after debonding occurs:

        • Choose Step (default) to release the traction during the increment that follows debonding.

        • To avoid a sudden loss of stability, choose Ramp to release the traction gradually during succeeding increments that follow debonding.

      4. You can specify the rate at which crack propagation information is written to the data (.dat) file. If the step is using automatic time incrementation, the value is the suggested time increment to use for the first increment just after debonding starts. If the step is using fixed time incrementation, the value is the time increment after debonding starts if Abaqus/Standard finds it needs a smaller time increment than its current value. The time increment size will be modified as required until debonding is complete.

    5. Click OK to configure the VCCT crack and to close the editor.

  4. If desired, edit the general solutions control and adjust the VCCT Linear Scaling to accelerate convergence. For most crack propagation simulations using VCCT or the enhanced VCCT criterion, the deformation can be nearly linear up to the point of the onset of crack growth; past this point the analysis becomes very nonlinear. In this case linear scaling can be used to effectively reduce the solution time to reach the onset of crack growth. For more information, see Customizing general solution controls.