FEA Adhesive in a Bonded joint
FEA Adhesive in a Bonded joint
(OP)
Hi
I am modelling a part in which I have to bond with an adhesive a metal block withstanding a load.
To model the adhesive I figured different options
1) merge the nodes in adhesive areas
2) simulate the adhesive with elements
3) using spring elements between the two adherents
4) to use the laminate propriety of Femap and using like core the metal block
What is the best solution in your opinion? Where can I find some example?or do you have better idea?
Thanks
Regards
Engroma
I am modelling a part in which I have to bond with an adhesive a metal block withstanding a load.
To model the adhesive I figured different options
1) merge the nodes in adhesive areas
2) simulate the adhesive with elements
3) using spring elements between the two adherents
4) to use the laminate propriety of Femap and using like core the metal block
What is the best solution in your opinion? Where can I find some example?or do you have better idea?
Thanks
Regards
Engroma





RE: FEA Adhesive in a Bonded joint
Do you have material properties for the adhesive? does it have a nonlinear stress-strain response?
1) merge the nodes in adhesive areas
- generally won't give desired results
2) simulate the adhesive with elements
- generally the best approach, if required, but there are lots of details
3) using spring elements between the two adherents
- can be done, but generally more difficult than 2)
4) to use the laminate propriety of Femap and using like core the metal block
- not sure exactly what you are proposing, but probably won't give desired results
RE: FEA Adhesive in a Bonded joint
These metal blocks are secondary bonded between 4 carbon plies using an adhesive.
I would like to get the adhesive stress due to the load.
I can get the adhesive proprieties from the certification test we carry out on it.
How many details I need for the number 2?
thanks
RE: FEA Adhesive in a Bonded joint
http://femci.gsfc.nasa.gov/adhesive/index.html
And you may want to check www.materials-sciences.com. I know they've done quite a bit in adhesives modeling. Their SUBLAM software is pretty impressive in this area.
Garland E. Borowski, PE
Engineering Manager
Star Aviation
RE: FEA Adhesive in a Bonded joint
I'm guessing that your situation is more complex and this isn't the best solution. I'm certainly not an expert on FEA, but figured I'd toss the idea out there.
-- MechEng2005
RE: FEA Adhesive in a Bonded joint
Just be careful, for most element types even thin sections require 2 or 3 elements through the thickness in order to get good stress results.
BW www.akeng.com
RE: FEA Adhesive in a Bonded joint
I would like to get the adhesive stress due to the load.
> and what are you going to do with the adhesive stress?
I can get the adhesive proprieties from the certification test we carry out on it.
> what specific tests? what properties are measured?
As mentioned above, often several or more elements are needed thru the adhesive thickness. Also, nonlinear stress-strain properties are often needed to avoid stress singularities. Then there is the whole issue of failure criteria if you are trying to predict strength.
RE: FEA Adhesive in a Bonded joint
The specimens are made with the adhesive and adherents used in the part.
RE: FEA Adhesive in a Bonded joint
If your adhesive layers is 0.2 - 0.3 mm thickness, your solid element should not be more then 1 - 2 mm on the longer edge.
If you make a mesh so small you will have probably many problems to manage your model.
Using spring approach you overcome this problem.
To use the spring approach (See Gbor post for explanation) you must be very careful to connect very similar elements, because the stiffness property of each spring depend of area of surrounding elements. if you make different elements you should give to each spring a different stiffness! Not really feasible!
Best way is to mesh the two adherents with same mesh.
Regards
RE: FEA Adhesive in a Bonded joint
Check the web and also look for effects due to the high poisson ratio for many adhesives, i.e. elastomers that are incompressible