On the degradation of additively manufactured polymers and composites

Document Type

Article

Publication Date

4-12-2026

Abstract

This study proposes a physics-based, irreversible thermodynamic framework for evaluating degradation in additively manufactured polymer matrix composites under uniaxial tensile loading. Specifically, three material systems, Polylactic Acid Polymer (PLA), carbon fiber-reinforced PLA (PLA-CF), and carbon fiber-reinforced polyamide (PA-CF), were investigated across a range of raster orientations and crosshead speeds. The proposed framework employs two key thermodynamic performance parameters: the degradation coefficient ( B ) and the Failure Entropy Threshold (FET). The B coefficient is formulated based on the Degradation Entropy Generation (DEG) theorem, which relates material degradation to entropy generation, and FET is defined as the total entropy generated at the onset of fracture. Experimental validation, coupled with theoretical modeling, demonstrates that both B and FET are intrinsic to the material and to print orientation but remain largely independent of loading rate, establishing them as robust descriptors of material behavior. This entropy-based approach enables early-stage damage quantification and predictive modeling of remaining useful life (RUL) in fiber-reinforced AM composites. These findings provide a unified, mechanism-sensitive degradation framework that advances current understanding of failure in polymeric composites and supports the design of more durable, reliable composite components for structural applications.

Publication Source (Journal or Book title)

Composites Science and Technology

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