PVB linear viscoelastic/elastic

[SMS]

Hello Dr.Bergstrom and all,
I am modeling impact of hard/soft missiles on laminated glazing with PVB(poly vinyl butyral) as interlayer using abaqus explicit (v6.7).
The PVB properties used are:
density=1100kg/m3, Go = 1GPa, Ginf =0.69MPa, Beta=12.6/sec,K=2GPa.
I have used these data from earlier published literature. Here PVB is linear-viscoelastic.
While modeling in Abaqus, I have calculated the elastic constants E and v(poissons ratio) using K and Go and the visco-elastic parameters(time=prony) as: gi = 1-(Go/Ginf); ki=0; tau=1/beta.
I also ran an analysis defining PVB as elastic only.
The stress/displacement results are almost close for both linear-viscoelastic and elastic PVB.
This observation is consistent with that of published literature.
Only difference is in the time duration of analysis. In my case, both the cases take the same amount of time for analysis where as in the literature they mention that the analysis time is far higher in case of visco-elastic PVB than when it is modeled as elastic.
I was looking for a clarification in this regard. Thank you for your time.

Regards,
Mahesh

[Jorgen]

Are you saying that the time it took for your computer to solve the FE simulation was the same for the linear elastic and the viscoelastic case?

If so, that can be the case if the time spent updating the stress is small compared to other parts of the simulation (like inverting the stiffness matrix). The run time for a simulation is strongly dependent on the details of the simulation.

-Jorgen