Quasistatic - based analytical approach to predict fracture toughness in polymeric materials

Abstract

Mechanical fatigue causes catastrophic failures under cyclic loading even below a material’s static strength and accounts for most in-service failures of metallic and polymeric components, with significant economic impact. Obtaining crack growth curves and toughness parameters through fracture mechanics testing is often costly and time-consuming. To address this challenge, this work implements the FMDM theory (Fracture Mechanics of Ductile Metals), originally developed for ductile metals, integrated with the Paris–Newman thickness correction to estimate fracture toughness, K_lc, directly from standard uniaxial properties (modulus, yield, and postnecking plasticity) without relying on specialized fracture tests. The FMDM–Paris–Newman framework was applied to four materials with dissimilar microstructures (Tow ABS grades, POM, and Al). The estimated values of K_lc show excellent agreement with reported data, confirming that mechanical information (stress–strain response and plastic work metrics) is sufficient to enforce the plane strain condition in the K evaluation and, consequently, to guarantee the intrinsic, material property character of K_lc The key finding is that the approach does not require fine molecular structure characterization; instead, it relies on mechanical mapping of the uniaxial stress–strain response, including post-necking plasticity and plastic work metrics, onto an energy-based crack-tip model. This formulation, invariant to explicit microstructural description, explains its portability across dissimilar materials, while preserving physical traceability from the constitutive curve to the recovered toughness K_lc The outcome is a simple, traceable, and cost-effective analytic–experimental methodology, suitable for early-stage toughness estimation and simulation-driven design.