Modelling Adhesive Component In Bonded Joint PATRAN
Modelling Adhesive Component In Bonded Joint PATRAN
(OP)
Hi
I was wondering if there was any suggestions to how the adhesive componenet of the bonded joint could be modelled in PATRAN?
I was wondering if there was any suggestions to how the adhesive componenet of the bonded joint could be modelled in PATRAN?





RE: Modelling Adhesive Component In Bonded Joint PATRAN
However, if you do get an analysis to work, please do NOT rely on an average shear stress approach, and do not rely on an elastic analysis. A very significant amount of the strain energy to failure for adhesive bonds is derived from plastic behaviour.
Regards
Blakmax
RE: Modelling Adhesive Component In Bonded Joint PATRAN
If you want to get a bit more sophisticated then increase the mesh density a lot and model the glue with solids. With linear 8-node bricks You will probably need at least three elements through the glue thickness (glue is often about 0.01" or 0.25 mm thick).
It is more usual to do a simplified 2D model of a section through the glueline (perhaps towards the end of a glueline to estimate the elastic stress concentration). In that case the glue is just more 2D elements modeling its thickness. You still need a lot of elements and again about three elements through the thickness. A nonlinear analysis is advisable.
In the limit you can do what blakmax's friends did and essentially write your own code. I think that would only be a big advantage if you were worried about faliure of the glueline and wanted to model its behavior in detail non-linearly including plasticity. These days it might be more common to use a very nonlinear code (perhaps even an explicit one like Dyna or Abaqus Explicit) with appropriate elastic/plastic properties. You would need to get a measure of the glue's onset of yield (which is at quite a low strain) and the 'knee' where the glue gets more flexible in shear. See the Cytec datasheet on their FM 300 and FM 300-2 film adhesive for some representaive stress/strain curves. (E.g. page 8 of this datasheet http://www.cemselectorguide.com/pdf/FM_300-2_09271....)
Like all analysis you must plan about what use you want to make of the results (or what you want the results to tell you) and allocate resources appropriately. For instance if you want to model the effects of defects in the glueline you will probably need to consider the glue's toughness.