The effect of lathe checks on the mechanical performance of LVL

Laminated veneer lumber (LVL) is an important engineered wood product manufactured by bonding veneers together in grain direction. To understand the effect of lathe checks on the mechanical performance, three types of LVL with different assembling approaches of layering by taking into account the veneer lathe checks, namely loose-loose (LL), tight-tight (TT) and loose-tight (LT), were manufactured in the laboratory. The lap-shear test and digital image correlation (DIC) technique were used to record the mechanical properties and shear strain distribution simultaneously. The results show that there is a negative relationship between the amount of lathe checks and strength of LVL. The strength of TT type of LVL is significantly higher than that of LL type of LVL. Energy to failure of LT type of LVL is significantly higher than that of TT type of LVL. Clockwise shear strain is prone to occur in the bonding interphase, while both clockwise and anti-clockwise shear strain are found in the wood part of the veneers. The strength of LVL is mainly determined by the bonding strength of bond lines. The existence of lathe checks decreases continuous bond lines and deepens the adhesive penetration, which reduces the bonding strength. Mechanical strength of wood part plays a crucial role in the energy to failure of LVL. The effect of bonding interphase and wood part on the mechanical performance of LVL needs to be systematically considered. LT type of LVL has both high strength and energy to failure, and it is thus an effective assembling approach. The findings of this study can contribute to optimize the design strategies of wood veneer based composites.