## 3 Results
### Model Correlation  
A finite element model of the Charpy Impact was analyzed in LS-DYNA and the correlation of the model with experimental results was examined. The model is shown in Figure 9 where the setup consists of a 5.00 \(\times\) 0.50 \(\times\) 0.50 in. (12.7 cm \(\times\) 1.3 cm \(\times\) 1.3 cm) (length \(\times\) width \(\times\) height) wood specimen impacted by a 10.0 ft-lb (13.6 N-m) Charpy hammer at 11.4 ft/s (3.47 m/s). The wood specimen rests on a pair of rigid support brackets. The element mesh is very fine, so explicitly showing the mesh would not be beneficial. The simulation was processed using LS-DYNA R8.0 and postprocessed using LS-PrePost 4.1. To minimize the bias that may come with any anomalies associated with one specific test, the mean density of 0.026 lb/in\({}^{3}\) (719.7 kg/m\({}^{3}\)) and the associated strain-to-failure of 0.025 (per Equation (6)) of the maple data set were used for this finite element model. The resulting maximum deflection of \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Material Property**} & **LS-DYNA** & \multicolumn{2}{c}{**Units**} & \multicolumn{2}{c}{**Ash**} & \multicolumn{2}{c}{**Maple**} \\ \cline{3-8}  & **Material Variable** & **US** & **SI** & **US** & **SI** & **US** & **SI** \\ \hline Parallel Normal Modulus & EL & Ib/in\({}^{3}\) & GPa & 2,190,000 & 15.1 & 2,280,000 & 15.7 \\ Perpendicular Normal Modulus & ET & Ib/in\({}^{3}\) & GPa & 175,000,000 & 1.21 & 148,070,000 & 1.02 \\ Parallel Shear Modulus & GLT & Ib/in\({}^{3}\) & GPa & 238,438.0 & 1.64 & 252,858.0 & 1.74 \\ Perpendicular Shear Modulus & GTR & Ib/in\({}^{3}\) & GPa & 83,864.00 & 0.58 & 80,642.00 & 0.56 \\ Poisson’s Ratio & PR & — & — & 0.440 & 0.476 & \\ Parallel Tensile Strength & **XT** & Ib/in\({}^{3}\) & **MPa** & **24.4740.00** & **169** & **22.5130.00** & **155** \\ Parallel Compressive Strength & XC & Ib/in\({}^{3}\) & MPa & 12,090.30 & 83.4 & 11,227.02 & 77.4 \\ Perpendicular Tensile Strength & YT & Ib/in\({}^{3}\) & MPa & 1942.400 & 13.4 & 2163.920 & 14.9 \\ Perpendicular Compressive Strength & YC & Ib/in\({}^{3}\) & MPa & 1892.600 & 13.1 & 2107.850 & 14.5 \\ Parallel Shear Strength & SXY & Ib/in\({}^{3}\) & MPa & 3116.300 & 21.5 & 3341.050 & 23.0 \\ Perpendicular Shear Strength & SYZ & Ib/in\({}^{3}\) & MPa & 4362.800 & 30.1 & 4677.470 & 32.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: MAT_WOOD (MAT_143) maple and ash card 2 and 3 inputs. Figure 9: Charpy impact finite element model. the model before failure occurs is 0.137 in. (0.348 cm), which is very close to the 0.138 in. (0.350 cm) maximum deflection of sample M307B, a 0.026 lb/in\({}^{3}\) (719.7 kg/m\({}^{3}\)) density maple sample that failed at a strain of 0.0241. The model deflection of 0.137 in. (0.348 cm) falls within the mean deflection plus one standard deviation of 0.12-0.159 in. (0.308-0.404 cm) of the entire maple sample set. The model can be seen in Figure 10 with a high-speed video image for comparison. A series of finite element simulations of the Charpy impact tests was completed for maple and ash specimens and a span of wood densities for each of the two wood species. Summaries of the comparison of maximum deflection, that is, deflection just before fracture, of these maple and ash Charpy impact models with the corresponding test sample IDs are presented in Table 4, respectively. There is excellent correlation between the maximum deflection values between the experimental data and the model results.