Establishmen Of Finite Element Model Of Sheep Lung And Finite-element Simulation Of Blast Wave

Blast wave can cause damage to organisms,which is called blast injury. The case often occurred in many situations such as Wars, industrial accidents, terrorist attacks and so on. Injury degrees of organisms for blast wave is correlated with spread and distribution of shock wave pressure in vivo. Over years, the distribution of shock wave pressure has mainly been detected by the sensors installed in vivo,but the method has obvious disadvantage: real blast wave field can be influenced easily by many factors of environments;physical parameters can not be controlled perfectly; both of the stability and repeatability of animal damage are poor; preparation works are complex ,waveshaping experiments are too long ,costs are too expensive and so on. With the rapid development of bio-mechanics and computer simulation, finite element model and its analysis methods have already a wide range of applications in injury biomechanics and its related fields. Computer modeling and numerical simulation of blast wave damage is expected to be an effective means in the research of mechanism of shock wave damage. This program aims to construct a finite element model of sheep lung served as target organ of blast wave,which will be adapted to different kinds of blast waves and be accurate in geometry and highly fidelity.To solve all of the problems,this program established a experimental database system of biological weapons damage effects in order to manage the experimental data efficiently and scientifcally,which could support futher simulation analysis of finite element. Meanwhile, we construct the lung geometry models based on CT scans of lungs of sheep,and then construct the finite element model of sheep lung through the methods of division of grids and definition of parameters of lung materials. Subsequently, we calculate the acquired numerical values of distribution of stress-strain of sheep lung under the condition of blast wave by the method of fluid-solid coupling algorithm included in the software ANSYS/LS-DYNA,and evaluate the effectiveness of the finite element model and algorithms.Main research methods,results and conclusions as follows:①The weapons wounding experimental database was developed on the basis of requirement analysis for the investigation of weapon wounding effects and determination of the structure and login content. The database was constituted by three primary modules, namely, data inquiry, data management, and system maintenance. The MS Access2003 and Visual Basic 6.0 were applied to build the database management platform, and to develop the front-end interface respectively. The C/S was used as landing approach in the database. The information were classified into laboratory research and field test data, each including basic information of experimental animals, experimental conditions, wounding effects information, illustrations of injuried parts, physical parameters of weapons, and index management. The present database was available for the scientific and efficient management of experimental data of weapon wounding , which providing data support for the evaluation of weapon wounding effects.②we input the data acquired from the continuous sectional images of CT scanning sheep lung into Mimics software, and then extract the profile informations by the methods of setting gray level threshold and regional growth , reconstruct the geometric model of sheep lung through using surface rendering algorithm.③Optimized geometry model of sheep lung was imported into the software ANSYS ICEM CFD (AI), appropriate grids were selected to divide parameters; using tetrahedral elements divide grids. At the same time, we create a cube model to select hexahedral elements to divide grids. The formation of the spatial domain includes the lung model; two grids were exported in the form of the ANSYS command stream files by using the function of finite element grid of exportment in the software AI. And then we modify the types of documents into SOLID164 elements,increase keywords of defining material parameters,and define the boundary conditions of simulation experiments, including imposed blast wave pressures and constraints; after starting ANSYS / LS-DYNA software, entering the order flow of the modified files, you can import the sheep lung and space domain finite element model, a total of 133263 solid elements.④Using the software ANSYS / LS-DYNA ,we analyzed the stress-strain simulation distribution of on the sheep lung injuried by specific blast waves: four boundary occurred to normally displace by constraints of the space domain,and then we repectively imposed different blast wave pressures including50 kPa, 100 kPa and 200 kPa on the lung model, we utilized the method fluid-solid coupling algorithm included in the software ANSYS/LS-DYNA and evaluate the effectiveness of the finite element model and algorithms,finally we acquired an average lung pressure curve by calculating the numerical values under different conditions.⑤Through comparing injured sheep experiment measured data under the condition of blast waves to numerical simulation results,we found the two kinds of analyzed results are consistent with each other, namely the stress concentration mainly located on the edge of injuried lungs. So the method of effective finite element model of sheep lung could reflect the truth situations of injuried sheep lungs under the stress of specific blast waves has already been confirmed to be feasible.