Identification and variation of nonlinear elastic–plastic properties of poly(lactic acid) (PLA) foams produced by in-situ foaming additive manufacturing

Berezvai, Szabolcs and Tomin, Márton (2026) Identification and variation of nonlinear elastic–plastic properties of poly(lactic acid) (PLA) foams produced by in-situ foaming additive manufacturing. ADDITIVE MANUFACTURING LETTERS, 18. No. 100386. ISSN 2772-3690

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Abstract

Extrusion-based additive manufacturing technologies have undergone significant development in recent years, enabling the cost-effective production of complex geometries, customized designs, and small production series. Recent studies have shown that multilayer foam systems composed of layers with different densities can provide improved impact absorption performance. 3D-printing with in-situ foaming filaments offers a promising approach to the production of such functionally graded foams with controlled density distributions. This relies on materials that expand during 3D-printing, while the foaming can be controlled through the printing temperature. The accurate numerical (finite element) prediction of the nonlinear mechanical behavior of these density-graded structures requires an appropriate constitutive model and a material characterization strategy for in-situ foaming polymer foams printed at different temperatures. This paper focuses on the experimental characterization and constitutive modeling of an in-situ foaming poly(lactic acid) (LW-PLA) filament printed over a temperature range of (Formula presented). In compression (which is the characteristic loading of 3D-printed foams), the material exhibits finite strain deformation with yielding and nonlinear hardening properties. In this contribution, the isotropic Deshpande-Fleck crushable foam model with an associative flow rule is adopted for characterization of the measured material behaviour. Through carefully designed uniaxial mechanical tests and a dedicated post-processing method, the mechanical behavior of the foam is captured with high accuracy. Finally, the variation of the nonlinear foam properties as a function of the printing temperature is also identified.

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