Question: How can FEA be used to model the gradual failure of adhesives in composites?
Answer: You use the cohesive zone modeling technique.
Here is quick explanation of CZM from Andrew Main’s Use of Finite Element Analysis to Create Robust Composite Designs – Going Beyond First Ply Failure.
Unlike virtual crack closure, cohesive zone modeling uses an interface element to model t he adhesive joint that is failing. This gives the advantage that we can have a failure model for the adhesive which allows a gradual release. This is suitable for flexible adhesives. Figure 8 shows a typical stress/strain plot for a cohesive material. The area under this represents the “cohesive energy” or critical energy release rate.
This failure modeling approach is more appropriate for a non-brittle failure mode, which may be more common than we think! Epoxy resins do show a visco-elastic behavior which is not really brittle.
Watch a webinar on modeling composites. Jump to 32:40 for more on CZM.
Want to expand your knowledge?
- Watch a YouTube playlist on Composite Material Analysis.
- Watch a YouTube webinar titled Failure Analysis of Composite Structures.
- Watch a YouTube webinar titled Progressive Ply Failure Analysis of Advanced Composites.
- Watch a YouTube webinar titled Modeling Composites with MSC Nastran.
Do you have a question? Email me at .