## 2 Materials and Methods
### Pelvic Fracture Prediction Performance Validation by Published Experiment Data  
The pelvic fracture predictive capability of the THUMS pelvis was validated by reconstructing an existing pelvic impact experiment performed by [PERSON] et al. (2012). The original experimental setup included a horizontal sled test table, a 22.1 kg impactor, a 500 N vertical load cell and a vertical baffle. As shown in the referenced experiment, the pelvis was cut from the third lumbar verteb to the middle femur, was seated upright and 500 N was loaded on the third lumbar vertebra. Next, the 22.1 kg impactor ran at 4-5.2 m/s and collided with the left great trochanter. The vertical baffle was fixed on the right side 30 cm from the pelvis, and the time history of the mutual distance between the left anterior superior iliac spine (LASIS) and right anterior superior iliac spine (RASIS) was recorded by an optoelectrical motion capture system. An FE simulation model was established in accordance with the referenced experiment in the LS-DYNA (LSTC, Livermore, CA, USA) software (Figure 2). Since the RASIS-LASIS distance involved in the experiment data is 222.4 mm while the distance of THUMS model is 216.45 mm, we scaled the THUMS pelvic model with a factor of 1.027 (222.4/216.45). The rotations about the \(X\), \(Y\), \(Z\) axes of the model were restricted; The translations in the \(X\), \(Z\) directions of the lower nodes were restricted (Boundary-Spc); a lumped mass of 50 kg was loaded onto the top surface of the sacrum; global gravity was applied; the impactor was modeled as a rigid plane with a mass of 22.1 kg and initial velocity of 4 m/s; the right baffle was modeled as a fixed rigid wall, and the contact between the impactor and pelvis was modeled by the keyword * AUTOMATIC_CONTACT_SURFACE_TO_SURFACE with a friction coefficient of 0.2 ([PERSON] et al., 2017). \begin{table}
\begin{tabular}{c c c} \hline
**Part** & **LS-DYNA Material Type** & **Material Properties** \\ \hline \multirow{6}{*}{\
\begin{tabular}{c} Hipbone/Acetabulum cortical \\ \end{tabular} } & & \(\rho\) = 2000 kg/m\({}^{3}\), E = 1730 MPa, \(\
u\) = 0.3, \(\sigma_{Y}\) = 34.5 MPa, \(\epsilon_{\text{fail}}\) = 0.0257, C = 360.7, \(p\) = 4.605, with plasticity \\  & Piecewise\_linear\_plasticity & strain-stress curve ((0.000, 34.5), (0.001, 56.4), (0.003, 73.4), (0.004, 89.6), (0.006, 104.0), (0.009, 114.0), (0.012, 121.0), (0.026, 127.5)) \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Sacrum cortical \\ \end{tabular} } & & \(\rho\) = 2000 kg/m\({}^{3}\), E = 1302 MPa, \(\
u\) = 0.3, \(\sigma_{Y}\) = 80 MPa, \(\epsilon\) = 360.7, \(p\) = 4.605, with plasticity strain-stress curve ((0.000, 80.0), (0.003, 110.0), (0.015, 120.0)) \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Sacrum spongy \\ \end{tabular} } & & \(\rho\) = 1000 kg/m\({}^{3}\), E = 40 MPa, \(\
u\) = 0.45, \(\sigma_{Y}\) = 1.8 MPa, \(\epsilon\) = 13.3 MPa, \(\epsilon_{\text{fail}}\) = 1, with plasticity strain-stress curve ((0.02, 2.066), (0.04, 2.306), (0.05, 2.320), (0.06, 2.320)) \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Hipbone spongy \\ \end{tabular} } & & \(\rho\) = 862 kg/m\({}^{3}\), E = 15 MPa, \(\
u\) = 0.45, \(\sigma_{Y}\) = 0.675 MPa, \(\epsilon\) = 4.99 MPa, \(\epsilon_{\text{fail}}\) = 1, with plasticity strain-stress curve ((0.02, 0.775), (0.04, 0.865), (0.06, 0.870), (0.50, 0.870)) \\ \hline \multirow{2}{*}{
\begin{tabular}{c} Hipbone spongy \\ \end{tabular} } & & \(\rho\) = 862 kg/m\({}^{3}\), E = 15 MPa, \(\
u\) = 0.45, \(\sigma_{Y}\) = 0.675 MPa, \(\epsilon\) = 4.99 MPa, \(\epsilon_{\text{fail}}\) = 1, with plasticity strain-stress curve ((0.02, 0.775), (0.04, 0.865), (0.06, 0.870), (0.50, 0.870)) \\ \hline \end{tabular}
\end{table} 
Table 1: Material parameters of the constitutive model of THUMS pelvic bones. Figure 2: Impact loading conditions of the pelvic FE model in the validation experiment. As shown in Figure 3, the predicted time history curves of the mutual RASIS-LASIS distance were roughly consistent with the reported experimental data.