Time lag in micromechanical viscoelastic model

[tonydino82]

Hi,

I have been trying to develop a micromechanical model for a composite material (asphalt concrete) in ABAQUS. There are two layers in my model, stone (elastic) and asphalt-mastic (viscoelastic). For the viscoelastic model I used Prony series, below are my laboratory determined coefficients for gi, ki and tau, respectively: Temperature model parameters are , C1 C2 ref. temp = 40C
51.60 524.32

0.680145196 0.680145196 0.006491248
0.140528279 0.140528279 0.006490248
0.128376203 0.128376203 0.077028183
0.027891741 0.027891741 1.101221013
0.005270496 0.005270496 0.2

THE PROBLEM IS when I run the model for my composite material, I do not get any time lag between stress and strain although there must be some according to our lab test results related to the viscoelastic behavior of asphalt-mastic. Does anybody have an idea why I dont get time lag? I am checking the time lag by plotting Displacement vs. Total force (load is applied by using a displacement boundary condition since the test I am trying to simulate is strain controlled)

I look forward to hearing from you guys!!!

Thanks

Tony

 

[Elabbasi]

Make sure the analysis type is VISCO not STATIC.

Nagi Elabbasi

http://www.veryst.com

 

[tonydino82]

Hi Ellabbasi,

I used VISCO.

 

[Elabbasi]

How does the applied displacement vary with time? If it is applied too fast or too slow (what constitutes fast and slow depends on your viscoelastic constants) then there would be no significant viscoelastic effects and therefore no time lag.

Nagi Elabbasi

http://www.veryst.com