Dhondtguido
commented
1 year ago Hi disla2, I had a look at this problem. Due to the TIME POINTS parameter the energy is indeed not correctly calculated. I corrected the error, the correction will be available in the next update, probably at the end of July 2023. Thanks for pointing this out,
Guido
Hello Mr. Dhondt
Strain Energy density final value deviates from analytical solution for hyperelastic models Neo Hookean and Mooney Rivling with (C01=0). Issue could extend to Polynomial and relatives. Analytical solution= 0.525 MPa (Confirmed with Abaqus) Result = 0.79 MPa
Nominal stress and Strain curves agree with expected solution but not the final Strain Energy density computation. As a Hyperelastic model, strain energy density is a potential and I would expect solution only depends on final state (stretch lambda_u and C10 coefficient). I would appreciate if you could look at it.
Forum thread: https://calculix.discourse.group/t/strain-energy-density-neo-hookean-mooney-rivlin/1686
Hyperelastic Neo Hookean Mooney-Rivlin Strain Energy .pdf
`NODE 1,0,0,0.1 2,0,0,0 3,1,0,0.1 4,1,0,0 5,0,-0.1,0.1 6,1,-0.1,0 7,0,-0.1,0 8,1,-0.1,0.1 ELEMENT,TYPE=C3D8 1,6,8,3,4,7,5,1,2 ELSET,ELSET=Hexahedral 1 SURFACE,NAME=Moving_face 1,S1 SURFACE,NAME=Base 1,S2 MATERIAL,NAME=Neo_Hook HYPERELASTIC,NEO HOOKE 900000,2E-10 MATERIAL,NAME=Mooney_Rivlin HYPERELASTIC,MOONEY-RIVLIN 900000,0,2E-10 SOLID SECTION,ELSET=Hexahedral,MATERIAL=Mooney_Rivlin BOUNDARY 1,1,,0 1,2,,0 2,1,,0 2,2,,0 2,3,,0 3,2,,0 4,2,,0 4,3,,0 5,1,,0 6,3,,0 7,1,,0 7,3,,0 AMPLITUDE,NAME=A_1 0,0 500,-0.5 TIME POINTS,NAME=timepointsname 1 STEP,NLGEOM=YES,INC=110,AMPLITUDE=STEP STATIC 5,500,0,5 BOUNDARY,AMPLITUDE=A_1 3,1,,-1 BOUNDARY,AMPLITUDE=A_1 4,1,,-1 BOUNDARY,AMPLITUDE=A_1 6,1,,-1 BOUNDARY,AMPLITUDE=A_1 8,1,,-1 NODE FILE,GLOBAL=YES,TIME POINTS=timepointsname U,RF EL FILE,TIME POINTS=timepointsname S,NOE,ENER,E EL FILE ENER
EL PRINT, ELSET=Hexahedral ENER END STEP`