Quantifying the static tensile stress response of notched steel specimens using the degradation entropy generation (DEG) theorem

Document Type

Article

Publication Date

8-1-2026

Abstract

This study proposes a thermodynamic framework for evaluating material degradation in three steel alloys, AISI 1018, SS 410, and SS 316L, subjected to uniaxial tensile loading with varying stress concentrators, ranging from unnotched specimens to geometries with single notches, double notches, and center holes. The framework introduces two key thermodynamic parameters: the degradation coefficient (B), formulated under the degradation entropy generation (DEG) theorem, and the failure entropy threshold (FET), both grounded in the second law of irreversible thermodynamics. While the FET, defined by the entropy accumulated at fracture, was observed to vary with both material type and the severity of geometric discontinuities, the B coefficient remained invariant with respect to geometric discontinuities but exhibited sensitivity to material type—demonstrating its role as a material-specific constant. The proposed framework was validated through the finite element method (FEM) in ABAQUS, employing a ductile damage model capable of capturing necking and failure behavior. A strong correlation between experimental findings and FEM results was observed for both stress-strain behavior and the derived thermodynamic parameters (B and FET), validating the proposed thermodynamic framework. This thermodynamics-based approach offers a scalable and predictive methodology for assessing damage evolution and forecasting the remaining useful life (RUL) of metallic components under complex loading conditions.

Publication Source (Journal or Book title)

Mechanics of Materials

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