Session: 03-10-02: Micromechanics and Multiscale Modeling

Paper Number: 158441

158441 - Microplane Constitutive Model for Tension-Compression Asymmetry, Pressure Sensitive Damage and Size Effect in Polymers 

The multi-axial damage behavior of brittle polymers is highly complex, involving stark tension-compression asymmetry, strong pressure sensitivity, and size effect in fracture. These aspects are challenging to predict via phenomenological tensor-based damage models. Recognizing that these responses originate from various microscale damage mechanisms, this work presents a novel adaptation of microplane constitutive model for these materials. In this approach, “microplanes”, which are imagined planes of various orientations within the material microstructure, facilitate distinct formulations of tensile and compressive damage mechanisms via stress-strain vectors acting on these planes. The homogenized macro-scale stress tensor is obtained via the principle of virtual work. The multi-scale structure provides an intuitive, physically grounded way to model microcracking in tension, shear-driven plastic-frictional damage, and post-peak compression hardening. Beyond the capabilities previously demonstrated, the model now includes a volumetric tensile softening law, enabling the prediction of mode I fracture. The crack band approach is employed to introduce an intrinsic length scale, ensuring that the dissipation of fracture energy does not depend on the finite element mesh size. As a result, the model can correctly capture the size effect on structural strength and toughness. The calibration and validation span uniaxial tension, compression, triaxial compression, and three-point bending tests of various specimen sizes. This comprehensive validation shows that the model can accurately capture tension-compression asymmetry, pressure sensitivity, and the experimentally observed size effect, offering an effective predictive tool for the fracture behavior of brittle polymers.

Presenting Author: Sanket Vinod Wardhekar Stony Brook University

Presenting Author Biography: Sanket Wardhekar is a Ph.D. candidate in Mechanical Engineering at Stony Brook University, specializing in solid mechanics. His research focuses on constitutive modeling, fracture mechanics, and advanced material simulations.