## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### Convergence Problem during Static Strutural Analysis of Tubular Bonded Joint

• Guilherme Nunes
Subscriber

Hello everybody,

I'm currently trying to analyse a tubular bond between CFRP and Aluminium. I am modelling the adhesive layer as well, since I'm trying to compare some results with a collegue that is doing the same analysis in the lab. One of the extremeties is fixed (fixed support on the CFRP face), while one is loaded (Aluminium face on the other side).

However, there have been a lot of convergence problems. I've tried changing to displacement instead of aplying force as it is easier to converge, and it did do the trick for a smaller amount of displacement (0.55 mm), however as I ramped those values up the problems reapeared. The displacement is ramped in 200 steps from 0 to 1 mm (ideally I would do for 1.2+ mm to see the maximum strenght of the bond), with 100 min substeps and 1000 max substeps. Don't know if that's too much, but it's more of desparation...

I'm using bonded contact on both faces, so CFRP to Adhesive and Aluminium to Adhesive, with pure penalty formulation. I've changed the stiffness factor but it didn't help.

For the materials I'm using CFRP and non-linear aluminium from the Engineering database, the adhesive has data from the manufacturer, Both contact surfaces have a fracture input for contact debonding with a CZM that I inputed as well based on previous experiments. I've made a command to try and insert my stiffness value for the contact itself, but it caused more problems than not.

The mesh of the contacts is of 2 mm, the rest is basically set to default values. The paths are set so that I can see the stress on the bonded lenght (I'm also trying to get a bond-slip graph, but haven't found a way to do it properly).

If somebody could help me with this, I would really appreciate it, as this thing is eating me alive mentally.

Thank you

• Guilherme Nunes
Subscriber

Is there a way to attach my .wbpz project in here?