## 3 Results and Discussion  
### Mechanical Properties  
The results of the MOE, MOR, and strain at break are presented in Figure 2. The MOR and strain at break generally increase with an increase in the slicing thickness, demonstrated by the increasing median value (red line), the position of the interquartile range (the box) (Figure 2), and the mean group values (Table 1). The MOR was significantly lower for the 1.5 mm thick sliced lamellae, with a mean of 0.8 N mm\({}^{-2}\), compared to 1.16-1.43 N mm\({}^{-2}\) (mean value) for the 2.5 to 4.5 mm thick sliced lamellae, with no significant differences between the 2.5-4.5 mm groups (Table 1). The positive correlation between the slicing thickness and MOR is thought to be due to the increased thickness of the unchecked wood with increasing sliced lamellae thickness, and aligns with the findings on rotary-cut birch veneers [23].  
The failure of the sliced lamellae that were subject to tension in the perpendicular-to-grain direction occurred mainly in the radial direction. The sliced lamellae's reduced strength, i.e., several times lower than alternative species studied [6; 23], were probably due to the oak species' loose-cut slicing check characteristics and the material's low strength features, such as large earlywood vessels [40].  
Figure 2: Effect of sliced lamellae thickness on the MOR (**upper left**), strain at break (**upper right**), and MOE (**lower**).  
The results indicate that the strain at break increased with the increasing sliced lamellae thickness from 1.37% for 1.5 mm to 2.64% for the 4.5 mm thick sliced lamellae (Table 1). The obtained results for the strain at break were statistically significant at a 95% confidence interval for the 1.5 compared to the 3.5 and 4.5 mm and 3.5 to 4.5 mm thick sliced lamellae group comparisons. The increase in the strain at break with the increasing sliced lamellae thickness could be explained by a crack opening displacement at the crack initiation point [41]. Therefore, sliced lamellae consisting of large slicing checks experience a significant opening phase under low stress at the beginning of loading. Hence, ascertaining the effect of clamping devices and specimen geometry should be further evaluated to validate the measurements' accuracy. Other potentially significant variations in the sliced lamellae properties impacting the results may be due to various factors such as raw material properties, drying, and slicing parameters, which were beyond the current study's experimental design limitations.  
The impact of the slicing thickness on the MOE perpendicular to the grain illustrates a somewhat independent variation (Figure 2 and Table 1). The obtained MOE of 110.7 N mm\({}^{-2}\) for the 1.5 mm thick sliced lamellae was about six-fold lower than the reported 0.5 mm thick beech sliced lamellae results [6], and about eight times lower than oak solid wood reported values [42]. These aspects reiterate plain-sliced oak lamellae's significantly diminished stiffness due to slicing check damage.  
Overall, plain-sliced oak lamellae's mechanical response behaviour resembles a quasi-brittle material, similar to solid wood. The most commonly identified stress-strain curves are shown in Figure 3. The stress-strain curves can be generally characterised by a nearly linear increase over the test course, with some specimens exhibiting a plastic strain behaviour during loading, followed by a continuous linear stress-strain increase (Figure 3 right). A possible reason for this behaviour may lie in the crack opening phase, followed by a fibre-bridging effect [1].  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Thickness** (mm)} & \multirow{2}{*}{**No. Samples**} & \multirow{2}{*}{**Mean**} & \multirow{2}{*}{**Coeff. of Variation (\%)**} & \multirow{2}{*}{**Standard Error**} & \multirow{2}{*}{**C.1. 95\% of the Mean**} & \multirow{2}{*}{**2-Way ANOVA \(p\)-Value \(p\)-