Modeling of Viscoelastic Damper

[atakulaksizoglu]

Hi everyone. I am a beginner in Abaqus and I am trying to model a viscoelastic damper to obtain the hysteresis curve. I will use the model as a basis for the experimental program I will perform within the scope of my PhD thesis. Basically, I have defined three parts/sections for the steel plates and two parts/sections for the rubber pad sandwiched in between the central plate and the side plates. I have two major issues I am having troubles with.

First, according to my research, a Neo-Hookean hyperelastic model and a viscoelastic model with appropriate coefficients defined is enough to simulate rubber behaviour. And since those coefficients change significantly with different types of rubber, it is not logical to ask 'which coefficients should I use?'. So it is appropriate to obtain those values from test results of the material I will use in the experiment.

Second, what is the best way to model the surface interaction between the rubber and the steel plates. Basically, rubber pads are going to be bonded to the steel plates by special adhesives, and since they will work essentially under shear strain, it is vital to model the interaction surface to obtain realistic results. Which functions of Abaqus would you guys recommend me to use in modelling of the bond?

Thanks a lot in advance for any help.

 

[IceBreakerSours]

There are three aspects to this. Depending on how your questions evolve as you play around with your thesis work, you might end up using the simplest to the most complex functions that Abaqus provides, which is why, I think, you should learn about isotropic hyperelasticity as a first step (continuummechanics.org will be an excellent resource for you). There are many models available for rubber (Neo Hooke, Mooney-Rivlin, Ogden, Yeoh, Marlow, etc. to Arruda-Boyce). Likewise, in modeling viscoelasticity, you can go from simple lumped models, to Prony series and all the way to nonlinear viscoelasticity (Bergstrom-Boyce) models with or without Mullins effect, among other phenomena. Also, in parallel, you might want to learn about how contact (or, interaction) works in the finite element method. There are tonnes of resources available online in understanding how contact is supposed to work.

Unless the specific type of rubber is well studied, you may very likely have to perform your own experiments. You must gain a solid theoretical background before you perform your experiments. For instance, would you need multiple modes of deformation to calibrate your material model? Or, will you get away with just a uniaxial compression test? Simulia Learning Community has lots of good material on calibration of material models that will prove to be enormously valuable (using Excel, ISight, Python, etc.). Also, you have to be *very* careful in performing these tests to make sure the deformation state is, in fact, uniform in the gage section.

What will also help you is if you understood the trade-offs between implicit (Abaqus/Standard) and explicit (Abaqus/Explicit) numerical schemes so you can choose a path going forward.

Finally, pay loads of attention to simplifying the geometry and minimizing the DOFs so you can iterate fast.

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[atakulaksizoglu]

IceBreakerSours thanks a lot for the reply, it was very enlightening. I will look at the references you gave.