Crack growth through partition?

[Ply22]

Hey guys,

i am currently simulating crack growth and Propagation Analysis on on a coated substrate during an indendation process via XFEM. I am not only interested in the initial crack, but rather in the whole cracking process during the complete simulation. To my understanding, multiple cracks will only propagate, after the XFEM enriched feature is seprated by one crack or if multiple cracks emerge during the same time increment. Now my idea was to create multiple partitions with multiple XFEM enriched zones.

My question now is: If a crack propagates through material and reaches another partition with the same XFEM parameters applied, does the crack initiation criterion (in my case MaxPs) need to be fullfilled once again or does the crack just propagate through the second partition normally using the Evolution criterion?

Thank you very much in advance

 

[FEA way]

It seems that you use Abaqus, right ? In such case check the documentation chapter "Modeling discontinuities as an enriched feature using the extended finite element method" —> "Defining an enriched feature and its properties". You should use multiple enriched zones if you want the cracks to appear sequentially at different locations.

 

[rb1957]

we need a ton (literally a ton, more information.

How are is the structure bonded together ? What are the materials ? What are the crack starters ?

This new layer that the crack is encountering could be a "tear strap" … a separate piece of structure that slows the crack propagation ('cause it spans/restrains the opening of the crack) until the load in the strap causes it to fail.

To get anything close to the "truth" you'll need to test.

another day in paradise, or is paradise one day closer ?

 

[Ply22]

Thank you for the answers and yes, i am using abaqus. I read the chapter and it was quite informative, i am still unsure if the initiation criterion has to be fullfilled once again when the crack reaches a new enriched partition of the same material.

Materials are CVD Diamond, so a very hard, brittle material. Substrate is a cemented Carbide. I am using the cohesive Zone model within the CVD layer with MAXps as the crack initiation criterion. I have no imperfection in the model, the crack usually initiates in the interface area between substrate and coating.