Applying Cohesive Zone Modeling: General Model Setup Questions
All, I'm currently working on a ANSYS model with utilizing CZM to simulate adhesively bonded lap joints. I have some general questions about getting the model setup correctly. I've tried to attach some images to better explain my questions. I should add that the lap joints are fixed at the end of one plate, and pulled in the axial (left/right direction of the screen) at the other end. I've added my questions are bullet points to try to separate out my questions. If there's any confusion, please let me know and I'll clarify!
- When the lap joint is constructed, the adhesive is applied between the two plates. This adhesive then has a thickness (maybe 0.1mm or so). Should this thickness be utilized in the ANSYS model? I've watched multiple videos on CZM, and everyone assumes the "plates" are in direct contact (as shown in the "current model" image, below. The CZM material is then applied directly at the contacting interface.
However, this seems inaccurate. Ultimately, CZM only represents the interface between the adhesive and the substrate (plates), not the actual behavior of the bulk material. If modeling the deflection and stresses, the layer thickness would have an effect, correct? Would I then model the bulk adhesive as a "solid", and define normal material properties, and apply CZM at both interfaces (top and bottom of the bulk adhesive, where it contacts the plate)? This is shown in the image below.
If the effect of this thin "bulk" adhesive layer is small, it's acceptable to ignore it. However, my initial results aren't close to the experimental data, so I'm guessing utilizing the direct contact has a major effect.
- When defining a CZM material, ANSYS provides four options. Two methods for debonding and two for delamination. What is the difference between debonding and delamination? How do you know which one to utilize?
- What contact formulation should be used? I've read some articles that specify utilizing "Pure Penalty" or "Augmented Lagrange". I guess I'm just curious what the advantages of each are? I've read some information about the theory, but most sources don't seem to speak much about the differences in application.
I'd truly appreciate any assistance! Thanks in advance!