Dear researchers,
i am currently simulating crack propagation in a CVD Diamond layer. I found relevant papers in which the Ramberg-Osgood model is being used to characterize the material behaviour of CVD Diamond, but i am lacking the in depth knowledge of this material model.
Could someone explain me the advantages and disadvantages of using the R-O model in ABAQUS CAE? Or rather what the restrictions of this model are.
Thank you in advance
Alexander Hannemann
The relationships between the strain ε and the stress σ can be expressed by the the Ramberg–Osgood equation:
ε=σ/E+(σ/C )1/n
where n is the work-hardening exponent, C the constant, and E the Young`s modulus.
However, this equation can not calculate σ directly from a given ε value, and numerical calculations should be used. So you may check if the software has a process function to do this. In general, stresses are computed from a displacement - strain - stress flow line in FEM.
Ramberg-Osgood uses in Abaqus software to simulate Crack, this model is available in Abaqus by "Deformation Plasticity" in the material section. There are different ways to use this model if constants were not available. Please read API 579 to understand how to exactly work with this material model.
The Ramberg-Osgood is a generalised model to decribe actual stress-strain curves. There are other curves: Swift, power laws etc.
Typically, you will need to know the actual stress-strain data from the material of interest. This will allow you to compare which stress-strain model fits and/or represents your data the best. Else you can always do an Elastic analysis with approximate youngs modulus if no excessive deformaiton or non-linearity is expected from the model.
Regards
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