| As explosive blasts continue to cause casualties in industrial accidents and war-time activities, there is a need for increased understanding of the mechanisms of blast trauma at organ level and a need for a more detailed predictive methodology.It has been a common method to use finite element method to simulate the explosive to research the blast injury effect on human body. By establishing half-limitless blasting model for different dynamite quality and grid size, overpressure and positive impulse could be calculated. Through the comparison and analysis with the testing data, the error could never be neglected when the finite element program simulated the blasting field using dynamite explode method. This paper provided a method to acquire different types of blast waves. The curve of internal energy per unit volume with time was calculated with equation of state for air linear polynomial and revised with the modified formula, then imported into loading area of shock wave. The required shock wave was acquired by use of finite element program LS-DYNA. With the method given by this paper, blast wave of any type can be effectively and precisely simulated, providing effective route for research on blast injury.The location, extent and mechanism of lung injury under blast waves have always been concerned by researchers. A simplified finite element model of human thorax was established and the proper model of material and parameters were selected. The mechanical interacting process of blast waves and thorax was investigated by the finite element method of shock waves. According to the differences of the speed between different organs, the distributions of trauma area were predicted. The distribution of the lung organ trauma area was analyzed with the aid of the variation of tensile pressure of lung model. The simulated results were compared with the anatomy experimental and theoretic results. Wonderful consistence was obtained. The method proposed in this paper was effective and precise to simulate trauma characteristics and provided an effective route for research on blast injury.The process of shock wave acting on human thorax has been evaluated qualitatively and concerned very much. On the basis of Lobdell human thorax crash damage model, this paper proceeded with effective revision and improvement and obtained dynamic model of the human thorax under the influence of blast wave, furthermore, according to equations for deducing the model, reasonable calculation method was selected. After loading experimental data into the model as boundary conditions, the speed of movement in every direction and displacement of the lung, pressure in the lung cavity, stress wave in lung tissue, as well as the work that is done to lung tissue by blast wave were calculated, then the paper analyzed the relation between its regular pattern of variation and shock wave and injury effect, and based on the relation between normalization work and injury to the lung tissue, the ratio of every casualty ranking in the lung tissue were deduced, which were closely similar to the calculated results by INJURY8.2. It shows that human thorax model established in this paper can be applied for injury assessment of lung tissue in various environments.It is focused by the researchers about what dynamic behavior the wave interacting with cellular material will act. The propagation tests researching the wave interaction with the air and the cellular material have been carried. In the tests, the peak overpressure and the total overpressure loss have been quantitatively analyzed, the incidence, reflection and transmission of the wave together with propagation loss in the air have been calculated. It is assured that the attenuation of the wave in cellular material is mainly due to the internal consumption of reflection, transmission and composition, which are caused by the solid microstructure under the wave, and the energy absorb by the solid phase deformation. The cellular characters of low density, energy absorb provide an access to design the protection material.Simplified finite element models are proposed to investigate the shock wave interaction with cellular foam. Based on the simulation results, it is found that the reflecting efficiency of cellular foam against the shock wave, the mechanical properties of shock wave propagating in internal cellular foam and transmitting over the cellular foam are observed. It is indicated that part energy of the shock wave is consumed by the reflection and structure deformation, and that part energy of the shock wave transmits through the cellular foam. Comparing the experimental data with the simulation results, the errors for attenuation percentages of peak overpressure and positive impulse are both within10%. The results show that the simplified finite element models and the numerical method used in this paper are effective and reasonable to investigate the mechanical process of cellular foam being exposed to shock wave. |
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