# Contact cohesive behavior

 The capability described in this section can be used to model a bonded interface, with or without the possibility of damage and failure of the bond, and to model regular contact behavior where the interface is not bonded. This capability has similarities to other features that could be considered for a bonded interface, including cohesive elements (see About cohesive elements). Cohesive contact behavior is typically easier to define than modeling the interface using cohesive elements and allows simulation of a wider range of cohesive interactions, such as two sticky surfaces coming into contact during an analysis. Contact cohesive behavior is primarily intended for situations in which the interface thickness is negligibly small. If the interface adhesive layer has a finite thickness and macroscopic properties (such as stiffness and strength) of the adhesive material are available, it may be more appropriate to model the response using conventional cohesive elements (see Defining the constitutive response of cohesive elements using a continuum approach). In Abaqus/Explicit the surface-based cohesive behavior framework can also be used to model crack propagation in initially partially bonded surfaces via linear elastic fracture mechanics principles (LEFM) as implemented using the Virtual Crack Closure Technique (VCCT). Contact cohesive behavior: is defined as a surface interaction property; can be used to model the delamination at interfaces directly in terms of traction versus separation; can be used to model “sticky” contact (i.e., surfaces or parts of surfaces that are not initially in contact may bond on coming into contact; subsequently the bond may damage and fail); can be restricted to surface regions that are initially in contact; allows specification of cohesive data such as the fracture energy as a function of the ratio of normal to shear displacements (mode mix) at the interface; assumes a linear elastic traction-separation law prior to damage; assumes that failure of the cohesive bond is characterized by progressive degradation of the cohesive stiffness, which is driven by a damage process (in Abaqus/Explicit brittle fracture can also be modeled using a VCCT fracture crierion); allows specification of postfailure cohesive behavior if failed nodes re-enter contact; is implemented within the general contact algorithmic framework in Abaqus/Standard and Abaqus/Explicit and within the contact pair framework in Abaqus/Standard; is enforced with the surface-to-surface, edge-to-surface, edge-to-edge, and vertex-to-surface contact formulations for general contact in Abaqus/Standard; is enforced only for node-to-face contact interactions in Abaqus/Explicit and is not available for edge-to-edge and node-to-analytical rigid surface contact interactions; is enforced for the node-to-surface contact formulation for contact pairs in Abaqus/Standard and is not available for the surface-to-surface contact formulation for contact pairs in Abaqus/Standard; can be used as an alternative to rough friction surface interactions, the no separation contact relationship, or a combined no separation and rough friction behavior within the general contact framework; is an alternative way to tie surfaces; and cannot be used in a coupled Eulerian-Lagrangian analysis in Abaqus/Explicit. The following topics are discussed:
 Related Topics About contact pairs in Abaqus/Standard About general contact in Abaqus/Explicit About mechanical contact properties In Other Guides About progressive damage and failure Defining the constitutive response of cohesive elements using a traction-separation description Crack propagation analysis *COHESIVE BEHAVIOR *SURFACE INTERACTION *DAMAGE INITIATION *DAMAGE EVOLUTION *DAMAGE STABILIZATION *FRACTURE CRITERION Specifying cohesive behavior properties for mechanical contact property options Specifying cohesive damage properties for mechanical contact property options

ProductsAbaqus/StandardAbaqus/ExplicitAbaqus/CAE