A Compact Micromechanical Model for the Elastic-Viscoplastic Deformability of PLA-Hemp Biocomposites

Abstract:

Despite the growing use of biopolymers in automotive, packaging and structural applications, predictive modelling of their elastic–viscoplastic deformation remains limited. In this work, a micromechanically based constitutive model is proposed to describe the micro‑ to macroscopic behaviour of a semi‑crystalline PLA matrix reinforced with short hemp fibers. The formulation relies on a multiplicative split of the deformation gradient into elastic and viscoelastic–plastic parts, with elasticity governed by fiber and crystalline phases and time‑dependent deformation localized in the amorphous phase. High fiber content and strong fiber–matrix bonding enable the suppression of lattice crystalline anisotropy, leading to a compact model with a reduced number of internal variables. The model is calibrated and validated using uniaxial tensile tests on pellet‑extrusion 3D‑printed specimens with controlled porosity and plasticiser content, and reproduces nonlinear loading, unloading, creep and stress relaxation. In a second step, synthetic data generated by the constitutive model are used to train surrogate machine‑learning models, which are discussed as a perspective for accelerating long‑term simulations and parametric studies in forming applications.

• Periodical: Solid State Phenomena (Volume 390)
• Pages: 197-205
• DOI: https://doi.org/10.4028/p-AoUE30
• Online since: April 2026
• Authors: Ndeye Niang, Sami Holopainen, Thierry Barrière*, Vincent Placet, Xavier Gabrion
• Keywords: 3D-Printing, Biocomposite, Forming, Machine Learning, Viscoplasticity

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