THE STUDY ON THE DAMAGE CHARACTERISTICS OF PINUS SYLVESTRIS VAR. MONGOLICA UNDER DIFFERENT MOISTURE CONTENTS
This study investigated the effects of moisture content (0%, 12%, 20%, 30%, 40%, 50%) on the mechanical behaviour and damage evolution of Pinus sylvestris var. mongolica three-point bending tests. A Weibull distribution model quantified damage progression, extracting scale (λ) and shape (k) parameters. Results revealed moisture regulated failure mechanisms, Low moisture (≤20%) induced brittle fracture (high k, low λ) with tensile crack dominance and stress concentration. High moisture (≥30%) promoted ductility (low k, high λ) via enhanced λ, driven by shear cracks. Mixed cracks persisted across all stages. Moisture altered cell wall plasticization, inter-fibre friction, and interfacial bonding, modulating damage evolution. Weibull modelling effectively captured stage dependent damage variable trends. Increased moisture facilitated fibre slippage and interlayer shear through lubrication and cell wall softening.This work establishes quantitative links between moisture content, mechanical response, and micromechanical damage mechanisms in wood, providing insights for moisture dependent structural applications of engineered timber.