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.

中文翻译：

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车床检查对LVL机械性能的影响

层积单板木材（LVL）是一种重要的工程木制品，是通过将单板沿纹理方向粘合在一起而制造的。为了了解车床检查对机械性能的影响，通过考虑单板车床检查，可以将三种类型的LVL具有不同的组装方法，即松动（LL），紧密（TT）和松紧（ LT）在实验室生产。搭接剪切试验和数字图像相关技术（DIC）用于同时记录机械性能和剪切应变分布。结果表明，车床检查量与LVL强度之间存在负相关关系。TT型LVL的强度明显高于LL型LVL。LT型LVL的失效能量显着高于TT型LVL。在粘结相中容易产生顺时针剪切应变，而在饰面的木质部分中同时发现顺时针和逆时针剪切应变。LVL的强度主要由粘合线的粘合强度决定。车床止回阀的存在会减少连续的粘合线并加深粘合剂的渗透，从而降低粘合强度。木材零件的机械强度在LVL破坏的能量中起着至关重要的作用。需要系统地考虑相间和木材部分的粘合对LVL力学性能的影响。LT型LVL具有很高的强度和破坏力，因此是一种有效的组装方法。这项研究的发现可以有助于优化木质单板复合材料的设计策略。