Hello everyone!

I am trying to model a linear viscoelastic material (pmma) in ABAQUS. I have frequency dependent data (complex modulus and complex poisson ratio as a function of frequency) and I have procceded to model it in the time domain.

ABAQUS models the material (pmma) but does not give the right results. I am studying stress waves in bars made of pmma and it is well known that material damping of the waves is suppose to be present.However, this is not the case.

I employed the evalution option in ABAQUS inorder to compare the material created by abaqus to that of my data and I found out that they were well apart.

My questions are, firstly, could this be a problem with ABAQUS calibrating the prony series coefficient form my data?Secondly,since it is not a problem with my data because they have been used elsewhere with success, could I possibly calibrate the prony series coefficient myself (e.g. following the prony series conversion paper by Dr Bergstrom)? If so could anyone point me towards an easy to understand explanation on implementing a good minimisation algorithim?Lastly, am I going totally towards the wrong direction?:oops:

Thanks so much in advance

GB