Primary blast waves induced brain dynamics influenced by head orientations

There is controversy regarding the directional dependence of head responses subjected to blast loading. The goal of this work is to characterize the role of head orientation in the mechanics of blast wave-head interactions as well as the load transmitting to the brain. A three-dimensional human head model with anatomical details was reconstructed from computed tomography images. Three different head orientations with respect to the oncoming blast wave, i.e., front-on with head facing blast, back-on with head facing away from blast, and side-on with right side exposed to blast, were considered. The reflected pressure at the blast wave-head interface positively correlated with the skull curvature. It is evidenced by the maximum reflected pressure occurring at the eye socket with the largest curvature on the skull. The reflected pressure pattern along with the local skull areas could further influence the intracranial pressure distributions within the brain. We did find out that the maximum coup pressure of 1.031 MPa in the side-on case as well as the maximum contrecoup pressure of −0.124 MPa in the back-on case. Moreover, the maximum principal strain (MPS) was also monitored due to its indication to diffuse brain injury. It was observed that the peak MPS located in the frontal cortex region regardless of the head orientation. However, the local peak MPS within each individual function region of the brain depended on the head orientation. The detailed interactions between blast wave and head orientations provided insights for evaluating the brain dynamics, as well as biomechanical factors leading to traumatic brain injury.

Preliminary Observations on the Biological Effect of Shock Waves with Prolonged Overpressure Duration and Exposures Repeated / 第三军医大学学报

Eight sheep and eigat goats were iniured in BST-I biological shock tube in order to observe the effects of shock waves with overpressure duration prolonged and exposure repeated on the injury severity. It is found that the more the overpresure dration prolonged and exposures repeated, the higher the incidence and the severity of the injury are seen. It suggestes that overpressure duration and number of times of exposure have marked effect on the severity of injury above certain peak pressure.

An underpressure generator of blast wave and its application / 第三军医大学学报

A generator has been designed to generate simulating underpressure of blast wave and applied for the study of underpressure injuries on animals.The generator is composed of a vacuum pump,a hypotcnsive chamber,an experimental chamber,a membrane-rupturing device and a pressure-measuring system.Its operating principle is as follows:When the pressure of the hypotensive chamber is being decreased by the drawing of the vacuum pump to a given level .the membrane separating the hypotensive chamber and the experimental chamber is rapidly perforated by a sharp pointer.Underpressure occurs in the experimental chamber where the animal is fixed as soon as the pressure changes instantaneously.The range of the physical parameters of the simulated underpressure are -13 to -90 kPa for the peak level,1 ms to 90 ms for the decreasing time,and 14 ms to 2000 ms for the duration.Animal experimentation revealed that this device is capable of inflicting injuries and verified the possibility that the underpressure of blast waves can result in injuries.

A comparative study on the propagation speed and physical parameters of underwater blast wave and air blast wave / 解放军医学杂志

Objective To compare the propagation speed and physical parameters between underwater blast wave and air blast wave. Methods The physical parameters of blast wave were measured by PCB pressure transducers (USA) during underwater and air explosions of 200g, 500g and 1000g TNT respectively. Consequently, the propagation speed, peak overpressure value, positive duration and impulse of blast wave were analyzed. Results Underwater blast wave was characterized by high propagation speed, high peak overpressure value, great impulse, however, short duration. Compared with air blast wave, the propagation speed of underwater blast wave was 3.70-4.30 times higher than that of air blast wave, the peak overpressure value was 227.15-247.86 times higher, and the impulse was 8.48-11.80 times greater than that of air blast wave. Conclusion Underwater blast wave propagates faster than that air blast wave. Meanwhile, it also peoduces higher peak overpressure value and impulse. This result is helpful for the evaluation of injury severity and treatment of underwater blast injury.

INVESTIGATION ON MECHANISM OF CERVICAL VASCULAR INJURY AFTER EXPLOSION IN RABBIT / 解放军医学杂志

To investigate the mechanism of common carotid artery injury produced by explosion in neck region, and to determine the severity of carotid injury based on the injury of neck and the pressure of blast waves. After the detonation of the blast source at different distances, the injuries to rabbits' neck and carotid artery were examined, and the pressure of the blast waves to both skins and common carotid artery were measured with PVDF(polyvinylidene fluoride)sensors and oscilloscope. The endothelium of the injured carotid artery desquamated and micro thrombus formed on the arterial walls the after injury. Disruptions in the tunica media might account for pseudo aneurysm formation. These results offered experimental evidences pseudo aneurysm and thrombus formation in the carotid artery after an explosion in the neek region.