Objectives: To reconstruct the cases of acceleration craniocerebral injury caused by blunt in forensic cases by finite element method (FEM), and to study the biomechanical mechanism and quantitative evaluation method of blunt craniocerebral injury.
Methods: Based on the established and validated finite element head model of Chinese people, the finite element model of common injury tool was established with reference to practical cases in the forensic identification, and the blunt craniocerebral injury cases were reconstructed by simulation software. The cases were evaluated quantitatively by analyzing the biomechanical parameters such as intracranial pressure, von Mises stress and the maximum principal strain of brain tissue.
Results: In case 1, when the left temporal parietal was hit with a round wooden stick for the first time, the maximum intracranial pressure was 359 kPa; the maximum von Mises stress of brain tissue was 3.03 kPa at the left temporal parietal; the maximum principal strain of brain tissue was 0.016 at the left temporal parietal. When the right temporal was hit with a square wooden stick for the second time, the maximum intracranial pressure was 890 kPa; the maximum von Mises stress of brain tissue was 14.79 kPa at the bottom of right temporal lobe; the maximum principal strain of brain tissue was 0.103 at the bottom of the right temporal lobe. The linear fractures occurred at the right temporal parietal skull and the right middle cranial fossa. In case 2, when the forehead and left temporal parietal were hit with a round wooden stick, the maximum intracranial pressure was 370 kPa and 1 241 kPa respectively, the maximum von Mises stress of brain tissue was 3.66 kPa and 26.73 kPa respectively at the frontal lobe and left temporal parietal lobe, and the maximum principal strain of brain tissue was 0.021 and 0.116 respectively at the frontal lobe and left temporal parietal lobe. The linear fracture occurred at the left posterior skull of the coronary suture. The damage evaluation indicators of the simulation results of the two cases exceeded their damage threshold, and the predicted craniocerebral injury sites and fractures were basically consistent with the results of the autopsy.
Conclusions: The FEM can quantitatively evaluate the degree of blunt craniocerebral injury. The FEM combined with traditional method will become a powerful tool in forensic craniocerebral injury identification and will also become an effective means to realize the visualization of forensic evidence in court.
目的: 利用有限元法对法医学检案中钝器打击导致的颅脑加速性损伤案例进行重构，研究颅脑钝器伤的生物力学机制和量化评价方法。方法: 基于已构建且经验证的国人头部有限元模型，参照法医学鉴定中实际案例，建立常见致伤工具有限元模型，利用仿真计算软件重构颅脑钝器伤案例。通过分析颅内压力、脑组织von Mises应力和最大主应变等生物力学参数，对实际案例进行量化评价。结果: 案例1第一次用圆形木棍打击左颞顶部时，最大颅内压力为359 kPa，脑组织最大von Mises应力（3.03 kPa）位于左颞顶部，脑组织最大主应变（0.016）位于左颞顶部；第二次用方形木棒打击右颞部时，最大颅内压力为890 kPa，脑组织最大von Mises应力（14.79 kPa）位于右颞叶底部，脑组织最大主应变（0.103）位于右颞叶底部，在右颞顶骨、右颅中窝处发生线形骨折。案例2用圆形木棍分别打击前额部和左颞顶部时，最大颅内压力分别为370、1 241 kPa，脑组织最大von Mises应力分别位于额叶（3.66 kPa）和左颞顶叶（26.73 kPa），脑组织最大主应变分别位于额叶（0.021）和左颞顶叶（0.116），在冠状缝左后方颅骨发生线形骨折。两个案例仿真结果的损伤评价指标超过其损伤阈值，所预测的脑损伤部位和骨折情况与尸体检验结果基本一致。结论: 有限元法能够量化评估颅脑钝器伤程度，与传统方法结合将成为法医颅脑损伤鉴定中有力的工具，也将成为实现司法鉴定出庭示证可视化的有效手段。.
Keywords: acceleration craniocerebral injury; biomechanics; blunt injury; finite element method; forensic medicine.