Correlation between non-destructive assessment of wood veneers and the resulting laminated veneer lumber

Abstract

This study investigated correlations between the mechanical properties of individual red maple (Acer rubrum) veneers and that of associated laminated veneer lumber (LVL). Veneers with an average thickness of 3.5 mm, width of 304 mm, and length of 2.44 m, were first subjected to a nondestructive test (NDT) using stress wave analysis. Dynamic modulus of elasticity (MOEd) was used to classify 480 veneers into four equal groups: high-grade, medium-grade, low-grade, and a mixed group. Each LVL consisted of 12 veneers bonded with polyurethane (PUR) adhesive. All LVL billets were evaluated nondestructively to determine their dynamic modulus of elasticity. Two different measurement systems were employed: a Fakopp Microsecond Timer was used for a time-of-flight approach and a Hitman HM200 (resonance acoustics approach) applied the longitudinal stress wave method and assessed its reliability for predicting the mechanical performance of LVL billets. A strong correlation (r = 0.85 and R² = 0.73) was found between the average MOE_dVeneer of veneers and that of the LVL billets (MOE_dLVL). There was a strong correlation between MOE_d from the Hitman HM200 device (MOE_dHitman) and that from the Fakopp device (MOE_dFakopp) (r = 0.93 and R² = 0.86).