Im trying to model a biaxial (cyclic shear static compression) test on an elastomeric bearing by using Ogden Model (MAT_077_O) in Ls Dyna. I obtained the material parameters ( and α,) from a uniaxial test in traction with the least square method:
1 = 239 2= 3347 3= -1082
α,1= 0.56 α,2= 0.057 α,3= 0.3
and Mass density RO =0.0014 , PR (Poissons ratio)=0.499
G :=Shear modulus for frequency independent damping = 0.9 MPa
SIGF :=Limit stress for frequency independent, frictional, damping =0
I really dont know what G and SIGF are.
The test aims to obtain a hysteresis loop (force displacement) which describes the behavior of neoprene in order to determine the dynamic shear modulus of neoprene.
For the mock up, I blocked at the bottom and blocked vertically on the top of the bearings. I disposed the harmonic displacement equivalent with 100% strain on all the nodes of the top. The frequency I applied is 0.5Hz.
The result seems not good because the bearing deforms enormously even the curve force displacement received resembles a hysteresis loop.
Can anyone help me with the material parameters from Ogden Model to accurate the result, the and α,, G, SIGF???? Or any model in Ls dyna which can describes approximately the hyper elastic or viscoelastic model of neoprene with the correct material parameters?
Thank you for your help in advance.