On the Feasibility of Identifying First Order Ogden Constitutive Parameters of Gelatin Gels from Flat Punch Indentation Tests

L. SANCHEZ FELLAY; L.A. FASCE; M. CZERNER; E. PARDO ; P.M. FRONTINI

SOFT MATERIALS

TAYLOR & FRANCIS INC

Lugar: Londres; Año: 2015

1539-445X

In this work, the feasibility of extracting First Order Ogden constitutive parameters of gelatin gelsfrom experimental flat punch indentation curves is considered. The adopted indentationconfiguration is that used in the technological Bloom test for gelatins. Eight gelatin gel samples ofdifferent formulations are prepared and evaluated. Identification of constitutive parameters (μ andα) is performed by an inverse method which combines finite element modeling simulations andnumerical optimization. Parameters are compared with those obtained from uniaxial compressionusing the analytical expression for the stress-stretch ratio relationship. Under uniaxial compression,gelatin gels display strain hardening over the Neo-Hookean model prediction. Multiple set of Ogdenparameters are identified depending on the initial guesses. A single set of Ogden parameters isidentified from flat punch indentation curves, which not always matches with those obtained inuniaxial compression. The origin of such discrepancy is investigated through a parametric study of theinfluence of μ and α on the shape of simulated flat punch indentation and uniaxial compressioncurves. Also, a sensitivity analysis of parameters re-identification is performed for two different