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Cohesive elements

Cohesive element modelling problem in ABAQUS

Dear All,

I am modelling a 3 point bend specimen with Cohesive elements tied to the upper and lower halves of the specimen in 2d.

The problem is that the CZ elements perform properly only for a combination of element sizes, i.e. a combination of element size of structure and CZ elements, for instance in my case the structure/specimen element size is 0.2mm and CZ is 0.001 or 0.002. For any other combination the adjacent elements bend as shown in the attached image.

I will be glad if someone could explain this behaviour and the solution.

Emilio Martínez Pañeda's picture

Abaqus2Matlab: A suitable tool for finite element post-processing

A new piece of software has been presented that connects the well-known FE code Abaqus with Matlab. The source code, detailed documentation and a large number of tutorials can be freely downloaded from www.abaqus2matlab.com 

Some interesting applications are addressed in the associated journal article:

http://www.sciencedirect.com/science/article/pii/S0965997816306512 (a pre-print is available at www.empaneda.com)

Simulating Pull-out test in abaqus

I have mediocre knowledge in abaqus. I want to simulate pull-out test of concrete and ribbed bars in abaqus. I am using a axis-symmetric element and using 1.0 mm thick cohesive elements for simulating the bond. What all the parameters to be given and how we have to assign the bond law in abaqus.( procedure in abaqus)Please help me. I am struggling from a lot of days. Thanks in advance.

matlab code to create cohesive elements (or UMAT) in any 2D mesh

To use cohesive elements, normally user can add a layer of elements between neighbouring node pairs. This matlab code can help you to process that especially your FE mesh is irregular. The code, the initial .inp file and corresponding out put files are attached for a better illustration. The new generated cohesive elements won't cause any trouble in the element number. Also you can apply this code to generate new UMAT elements in mesh.

 

ABAQUS-cohesive elements in compression

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Hi all,

how does ABAQUS design the cohesive element

Dear all,

I recently need calculate the stiffness matrix of the cohesive elements manually via mathematica. I used the finite element method to fulfill the assignment, but the result I got didn't match the stiffness matrix I extracted from the Abaqus. Neither did my supervisor.

knn, ktt and kss seem to be so obvious for the traction-seperation law, as also it measioned in Abaqus.  Could you please help me out by offering the way to find how the ABAQUS exactly design the cohesive elements or how ABAQUS calculate the stiffness matrix.

Solver settings in Abaqus/S for delamination analysis with cohesive elements

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Hi 
 
I have different 3D models of laminates where I analyse the delamination propagation using zero thickness cohesive elements in Abaqus/Standard. My experience with the RIKS solver and Newton solvers are that they are extremely sensitive to even small changes in the step size settings as well as other solver settings. 

Bonding of Soft and Rigid Materials

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I am workingon a model in which i have a soft layer of material bonded between to rigidlayers of material via cohesive elements following a linear separation-tractionlaw based on a critical fracture energy value I determined from experimentaland numerical work. I have the interlayer and cohesive elements as one partwith a partitioned face and connected to the two adherends viasurface-to-surface ties. I have found that my model runs successfully only ifthe soft interlayer material is made very stiff.

Cohesive Elements and Soft Materials

I am working on a model in which i have a soft layer of material bonded between to rigid layers of material via cohesive elements following a linear separation-traction law based on a critical fracture energy value I determined from experimental and numerical work. I have the interlayer and cohesive elements as one part with a partitioned face and connected to the two adherends via surface-to-surface ties. I have found that my model runs successfully only if the soft interlayer material is made very stiff.

If periodic boundary conditions do not respect stress continuity at the boundary....

Hi everybody,

have you ever tried to implement in Abaqus periodic boundary conditions?

I am doing this. Particularly, I am applying PBC to unit cells constituted of a clay particle in an epoxy matrix.

When I apply PBC in case of transverse shear, I have convergence problems using Abaqus standard,

so I have to use an algorithm of stabilization but because of this one

I have to renounce to the stress continuity between opposite boundaries of the unit cell.

Do you think this is normal or I am doing some mistakes?

Cohesive elements parameters

Hi,

I am working a long time on using cohesive elements in ABAQUS but up to now my efforts have be unsucessful.

I want to use of cohesive elements with the following paramters:

Damage initiation: Normal stres= 1.9 MPa, shear stress= 6.2 MPa 

Damage evolution:  Mode I fracture energy= 0.5307, Mode II farcture energy= 0.6623

Could any body kindly let me know that what would be my model E/Knn, E/Kss parameters?

Thank you,

Parisa

 

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