Cohesive Zone Master Action System
Description
The TensorMechanics system provides a cohesive zone modeling capability that can be used to introduce traction-separation models running at the interfaces between regions modeled with continuum finite elements. The implemented cohesive zone model (CZM) is based on a Discrete Galerkin approach and therefore does not require cohesive elements. The CZM is formulated in terms of traction separation laws and requires three ingredients:
BreakMeshByBlockGeneratorCZMInterfaceKernelsCZMMaterials
The BreakMeshByBlockGenerator is utilized to create the cohesive zone interface by splitting a monolithic mesh into blocks by adding the required nodes and boundaries between each block pair. The split mesh allows to compute a displacement jump at each quadrature point on the interface.
Small Deformations
A CZMInterfaceKernel utilizes the displacement jump to add the appropriate residual to the system and to provide the correct Jacobian. The current implementation of the CZMInterfaceKernel assumes the traction separation laws being only dependent from the displacement variables. Note that one CZMInterfaceKernel is required for each displacement component. The CohesiveZoneMaster block is used to simplify the process of setting up the necessary inputs required for cohesive zone modeling. It creates the appropriate number of CZMInterfaceKernel objects for the model dimensionality.
A CZMMaterial is used to compute the traction as function of the displacement jump and to provide the traction derivative $\frac{dT}{d \Delta u}. It should be noted that one can use different traction separation laws for different interface boundaries while using the same CZMInterfaceKernels. Furthermore, additional traction separation laws can be implemented by deriving from the CZMMaterialBase class (see for instance SalehaniIrani3DCTraction).
Even when using the CohesiveZoneMaster action it is the responsibility of the user to add the appropriate CZMMaterial and BreakMeshByBlockGenrator blocks in the input file.
Action to create an instance of the cohesive zone model kernel for each displacement component
Large Deformations
Large deformations have not been implemented yet. An error occurs when the user tries to manually set use_displaced_mesh = true in a CZMMaterial or in a CZMInterfaceKernel.