Quantifying fracture process zone evolution in magnesium-based wood-like material: Analysis based on digital image correlation and variation factor method

This study investigates the fracture behavior of magnesium-based wood-like material (MWM) under three-point bending using digital image correlation (DIC). The load-displacement curve exhibits asymmetric nonlinearity, reflecting sequential elastic deformation, plastic hardening, and post-peak progressive softening. A novel Variation Factor Method (VFM) is proposed to quantify fracture process zone (FPZ) tip localization through displacement variation analysis. VFM achieves < 2.14 % deviation from conventional methods while significantly improving computational efficiency. The FPZ strain threshold ε_xx of MWM is determined as 2.1 × 10⁻³, A_FPZ measures 315.02 mm² at peak load and reaches a maximum value of 639.33 mm² during post-peak damage progression. Plant fibers suppress crack propagation through a dual mechanism: plastic deformation dissipates energy within the FPZ, while elastic bridging redistributes stress, delaying post-peak degradation. These findings provide critical insights into multiscale damage mechanisms and offer a foundation for optimizing fracture-resistant quasi-brittle composites.