Abstract
The cohesive zone approach has gained increasing success in recent years for simulating debonding and fracture via finite element methods and is ideally suited for simulating adhesive joints, the potential crack paths being generally known in advance in most cases. In the paper the determination of the size of the so-called cohesive process zone is discussed, i.e. the region wherein the stress and damage state have to be correctly resolved in order to properly quantify the dissipated energy and the load bearing capacity of the structure. An a priori estimate for the size of the active process zone is provided based on the beam on elastic foundation model in which the material parameters of the cohesive law are incorporated. The formulation of the cohesive model in a damage mechanics format is first provided. The beam on elastic foundation model is then recalled and an approximate solution for the cohesive zone length is found that depends on a material length and a geometric parameter as well. Numerical results are presented for a Double Cantilever Beam (DCB) geometry with varying thickness for which bilinear and exponential cohesive laws are considered. The influence of the geometry and of the shape of the cohesive law are put forward in terms of global response and evolution of the cohesive process zone. The size of the process zone is found to be quite sensitive to the specimen characteristic size, whose influence is well captured even using a simplified modeling wherein the original cohesive law is changed into an ideal perfectly brittle one. This leads to fairly good estimates of the size of the cohesive zone compared to finite element results.
Highlights
The cohesive zone approach has gained increasing success in recent years for simulating debonding and fracture via finite element methods and is ideally suited for simulating adhesive joints, the potential crack paths being generally known in advance in most cases
The size of the process zone is found to be quite sensitive to the specimen characteristic size, whose influence is well captured even using a simplified modeling wherein the original cohesive law is changed into an ideal perfectly brittle one
This leads to fairly good estimates of the size of the cohesive zone compared to finite element results
Summary
The cohesive zone approach has gained increasing success in recent years for simulating debonding and fracture via finite element methods and is ideally suited for simulating adhesive joints, the potential crack paths being generally known in advance in most cases. At the onset of decohesion in a bonded joint the surface tractions between the joined adherends do not suddenly drop to zero owing to the presence of low-range interactions that precede the formation of traction-free surfaces Such interactions can be effectively described by allowing jumps in the displacement field along an interface where crack propagation is known or is expected to occur. The driving idea for such a class of models is the cohesive-zone concept initially introduced by Barenblatt [3] and Dugdale [4] This approach has gained major popularity in recent years for simulating delamination, debonding, fracture and fragmentation via finite element methods and is ideally suited for simulating adhesive joints, the potential crack paths being generally known in advance in most cases, see e.g. This approach has gained major popularity in recent years for simulating delamination, debonding, fracture and fragmentation via finite element methods and is ideally suited for simulating adhesive joints, the potential crack paths being generally known in advance in most cases, see e.g. [5,6] and references therein for recent survey accounts
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