MECHANICAL CHARACTERIZATION OF BOVINE GELS BY DEPTH-SENSING

SANCHEZ FELLAY, LUCAS; CZERNER, MARINA; FASCE, LAURA ALEJANDRA; FRONTINI, PATRICIA MARIA

Aveiro

Congreso; CIBEM5; 2012

Bovine gelatin gels are widely used in food industry as additives which have influence in the food's macroscopic structure, and hence its mechanical behavior. In this work, the feasibility of extracting the Stress-strain material parameters from an indentation test is investigated for bovine gels which obey the non-linear elastic Ogden constitutive model. For this purpose, a flat ended tip similar to that used in industrial indentation quality control tests was used. In the FEM simulations, the indenter tip is modeled as an axisymmetric rigid body and the test sample is modeled with quadrilateral lineal elements. The contact between the indenter and the material is assumed frictionless. FEM computational experiments are first performed with material parameters obtained previously from uniaxial compression tests. Then, varying the constitutive parameters, a set of finite element simulations are computed and used as input for an optimization algorithm in order to fit the true material parameters. Once the methodology is optimized, physically indentations are conducted and the Ogden equation is calibrated with real bovine gels. Finally, as an industry application contribution, dimensionless equations are developed in which the force versus displacement curve is fitted with the Ogden constitutive parameters, in order to simplify the methodology and make it easy to implement in practical situations.