Objective： To study the biomechanical mechanism of head injuries beaten with sticks, which is common in the battery or assaultive cases.Methods： In this study, the Hybrid-III anthropomorphic test device and finite element model （FEM） of the total human model for safety （THUMS） head were used to determine the biomechanical response of head while being beaten with different sticks. Total eight Hybrid-III tests and four finite element simulations were conducted. The contact force, resultant acceleration of head center of gravity, intracranial pressure and von Mises stress were calculated to determine the different biomechanical behavior of head with beaten by different sticks.Results： In Hybrid-III tests, the stick in each group demonstrated the similar kinematic behavior under the same loading condition. The peak values of the resultant acceleration for thick iron stick group, thin iron stick group, thick wooden stick group and thin wooden stick group were 203.4 g, 221.1 g, 170.5 g and 122.2 g respectively. In finite element simulations, positive intracranial pressure was initially observed in the frontal comparing with negative intracranial pressure in the contra-coup site. Subsequently the intracranial pressure in the coup site was decreasing toward negative value while the contra-coup intracranial pressure increasing toward positive values.Conclusions： The results illustrated that the stiffer and larger the stick was, the higher the von Mises stress, contact force and intracranial pressure were. We believed that the results in the Hybrid-III tests and THUMS head simulations for brain injury beaten with sticks could be reliable and useful for better understanding the injury mechanism.
Kui LiJiawen wangShengxiong LiuSen SuChenjian FengXiaoxiang FanZhiyong Yin
Objective： To establish an animal model to replicate the blunt impact brain injury in forensic medicine. Methods： Twenty-four New Zealand white rabbits were randomly divided into control group （n=4）, minor injury group （n：10） and severe injury group （n=10）. Based on the BIM- II Horizontal Bio-impact Machine, self-designed iron bar was used to produce blunt brain injury. Two rabbits from each injury group were randomly selected to monitor the change ofintracranial pressure （ICP） during the impact- ing process by pressure microsensors. Six hours after injury, all the rabbits were dissected to observe the injury mor- phology and underwent routine pathological examination. Results： Varying degrees of nervous system positive signs were observed in all the injured rabbits. Within 6 hours, the mortality rate was 1/10 in the minor injury group and 6/10 in the severe injury group. Morphological changes con-sisted of different levels of scalp hematoma, skull fracture, epidural hematoma, subdural hematoma, subarachnoid hemo- rrhage and brain injury. At the moment of hitting, the ICP was greater in severe injury group than in mild injury group; and within the same group, the impact side showed positive pressure while the opposite side showed negative pressure. Conclusions： Under the rigidly-controlled experimental condition, this animal model has a good reproducibility and stable results. Meanwhile, it is able to simulate the morphology of iron strike-induced injury, thus can be used to study the mechanism of blunt head injury in forensic medicine.
LI KuiCAO Yun-xingYANG Yong-qiangYIN Zhi-yongZHAO HuiWANG Li-jun
