Effect of flight helmet mass characteristics and neck stress postures on pilot neck impact injury

Pilots'ability is significantly improved by using night vision goggles and other equipment built on the flight helmets.Still,excessive helmet mass and centroid deviation caused by the integration of external equipment may increase the risk of neck injury of pilots during takeoff and landing.To reduce the risk of pilots'neck injuries under impact load,it is urgent to study the law of related factors on pilot's neck injury and provide theoretical support for the design of flight helmets.This paper establishes a finite element model of the pilot-seat-restraint system,and the effects of helmet masses,helmet centroids,and neck stress postures on the pilot's neck injury are systematically studied.The function rules of these factors on the neck load are clarified.This research can provide an essential reference for designing and optimizing flying helmets.

Interactions of primary insult biomechanics and secondary cascades in spinal cord injury： implications for therapy

The complex and variable nature of traumatic spinal cord inju- ry （SCI） presents a unique challenge for translational research. SCI is not bound by any demographic nor is it limited to specific injury biomechanics.

Human umbilical cord blood stem cells and brainderived neurotrophic factor for optic nerve injury: a biomechanical evaluation

Treatment for optic nerve injury by brain-derived neurotrophic factor or the transplantation of human umbilical cord blood stem cells has gained progress, but analysis by biomechanical indicators is rare. Rabbit models of optic nerve injury were established by a clamp. At 7 days after injury, the vitreous body received a one-time injection of 50 μg brain-derived neurotrophic factor or 1 × 10^6 human umbilical cord blood stem cells. After 30 days, the maximum load, maximum stress, maximum strain, elastic limit load, elastic limit stress, and elastic limit strain had clearly improved in rabbit models of optical nerve injury after treatment with brain-derived neurotrophic factor or human umbilical cord blood stem cells. The damage to the ultrastructure of the optic nerve had also been reduced. These findings suggest that human umbilical cord blood stem cells and brain-derived neurotrophic factor effectively repair the injured optical nerve, improve biomechanical properties, and contribute to the recovery after injury.

Biomechanical study of Essex-Lopresti injury

Objective To study the biomechanical mechanism of Essex-Lopresti injury,and provide biomechanical basis for diagnosis and treatment of Essex-Lopresti injury.Methods Twelve fresh frozen adult upper limbs were addressed.Firstly,12

Biomechanical behavior of brain injury caused by sticks using finite element model and Hybrid-III testing

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.

Study on pedestrian thorax injury in vehicle-to-pedestrian collisions using finite element analysis

Objective： To explore the relationship between the collision parameters of vehicle and the pedestrian thorax injury by establishing the chest simulation models in car-pedestrian collision at different velocities and angles. Methods： 87 cases of vehicle-to-pedestrian accidents, with detailed injury information and determined vehicle impact parameters, were included. The severity of injury was scaled in line with the Abbreviated Injury Scale （AIS）. The chest biomechanical response parameters and change characteristics were obtained by using Hyperworks and LS-DYNA computing. Simulation analysis was applied to compare the characteristics of injuries. Results： When impact velocities at 25, 40 and 55 km/h, respectively, 1） the maximum values of thorax velocity criterion （VC） were for 0.29, 0.83 and 2.58 m/s; and at the same collision velocity, the thorax VC from the impact on pedestrian＇s front was successively greater than on his back and on his side; 2） the maximum values of peak stress on ribs were 154,177 and 209 MPa; and at the same velocity, peak stress values on ribs from the impact on pedestrian＇s side were greater than on his front and his back. Conclusion： There is a positive correlation between the severity and risk of thorax injury and the collision velocity and angle of car-thorax crashes. At the same velocity, it is of greater damage risk when the soft tissue of thorax under a front impact; and there is also a greater risk of ribs fracture under a side impact of the thorax. This result is of vital significance for diagnosis and protection of thorax collision injuries.

Current state and progress of research on forensic biomechanics in China

Forensic biomechanics gradually has become a significant component of forensic science.Forensic biomechanics is evidence-based science that applies biomechanical principles and methods to forensic practice,which has constituted one of the most potential research areas.in this review,we introduce how finite element techniques can be used to simulate forensic cases,how injury criteria and injury scales can be used to describe injury severity,and how tests of postmortem human subjects and dummy can be used to provide essential validation data.This review also describes research progress and new applications of forensic biomechanics in China.

A Human Active Lower Limb Model for Chinese Pedestrian Safety Evaluation

A subsystem impactor test for pedestrian lower limb injury evaluation has been brought in China New Car Assessment Protocol(CNCAP).Concerning large anthropometric differences of the people from different countries,the present study aims to establish and validate a finite element lower limb model representing 50th Chinese male size for pedestrian safety research,then compare its biomechanical responses with the general models currently in wide use in the world for pedestrian safety evaluation.Concerning the vehicle-pedestrian impact loading environment,the previously developed lower limb model with three-dimensional muscles was adjusted and validated through the related experiments.Then,the biomechanical responses of the validated model were compared with the Total Human Model for Safety(THUMS)and Advanced Pedestrian Legform Impactor(aPLI)models by combing with four typical vehicles.The results showed that both consistency and significant differences of biomechanical responses existed between the present model and the other two models.The injury measurements of the thigh region of the present model showed extremely large differences with the other two models,while the tibia and Medial Collateral Ligament(MCL)injury measurements show similar values.Thus,it can be concluded that directly using the aPLI or THUMS models for Chinese pedestrian safety evaluation is not robust concerning both kinematic responses and injury measurements.