Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
A numerical-experimental methodology to characterize thermoplastic materials submitted to large strains
Submission Author:
Natália Mühl Castoldi , RS
Co-Authors:
Natália Mühl Castoldi, Francisco Luiz Bresolin, Jakson Vassoler
Presenter: Natália Mühl Castoldi
doi://10.26678/ABCM.COBEM2017.COB17-1329
Abstract
Thermoplastic materials submitted to tensile tests may suffer necking formation and propagation under large strains. These phenomena promote heterogeneous strains fields in the necking region which may mask the relation between the true stress-strain responses to the experimental force-displacement curve from a usual tensile test. A non-trivial numerical-experimental procedure is required since the resulting force data, obtained from a tensile testing, is not sufficient to assure the kinematics of the necking formation, which governs the force response. Thus, to characterize a material model, in this work a FEMU characterization methodology was employed. Experimental testing was performed on a modified polyvinyl chloride (PVC) specimen submitted to traction, where the applied displacement and the force response were obtained, respectively, from a clip-gauge and a load cell. Besides these traditional measurements techniques, the Digital Image Correlation (DIC) method was used to determine the displacement field occurring in the necking region to consider the necking kinematics. The constitutive model used to numerically characterize the material into the Finite Element Method Updating (FEMU) procedure was an elastoplastic model with multilinear isotropic hardening. The material parameter identification was performed using a hybrid optimization methodology combining genetic and gradient-based algorithms. Results obtained with the presented methodology showed that the studied model can reproduce the experimental force response. However, the cases analyzed were unable to represent the experimental displacement field from the necking region of the specimen.
Keywords
material characterization, Thermoplastics, DIC
