Dynamic Simulations And Preliminary Biomechanical Research On Blast Injuries Of Maxillary By Finite Element Method

Most of the wounded in modern military wars are explosive wounded.The frequency of domestic and international terrorist bombings has also increased over the past few decades.The information shows that the terrorist bombings have quadrupled worldwide during the period from 1999 to 2006,and the damage associated with these terrorist incidents has increased eightfold during the same period.Blast injury is a significant and complex problem facing military forces and health care workers.Animal,corpse and artificial materials were used to traditional models of maxillofacial blast injury.The anatomical structure of experimental animals is quite different from that of human body,so the experimental results are difficult to push the human body.Although the corpse is ideal as a research object,there is ethical limitations.The models making of artificial materials is technically difficult to achieve the complex geometric shape and biomechanical properties of human maxillofacial bone.The Finite Element Method(FEM)is to disperse the research object into a group of Finite units connected with each other in a certain way,which is to decompose the mechanical problem that the research object cannot directly solve into a plurality of simple solvable problems.The finite element method can be used for simulation various conditions,and can study the biomechanical response anywhere in the model,and output various forms of simulation results according to research requirements.In recent years,with the rapid development of computer hardware and software technology,the finite element method has become an ideal research method.With its unique advantages of repeatability,easy parameterization research,low cost and no moral and ethical restrictions,it has been widely recognized and widely used in the field of medical biomechanics.Therefore,this study aims to reconstruct the finite element model of human craniofacial bone by finite element method,give different biomechanical properties of materials,set boundary conditions and different injury conditions,simulate blast injury of the maxillary,and discuss the biomechanical response of the maxillary,as to provide theoretical basis and help for maxillary blast injuries.MethodObtaining CT images of a normal adult male,using a reverse-engineering method,using Mimics,Geomagic Studio,and HyperMesh software to build a finite element model of human maxillary in a non-invasive manner.To impart different material parameters to bone tissue,air and explosives.The temporomandibular joint is set to hinge movement.The nodes at the lower edge of the foramen magnum are restricted.The explosive equivalent was set to 500 mg and 1000 mg.The distance between the explosive and the anterior nasal spine was 3cm and 6cm.The simulation was performed the LS-DYNA software.The biomechanical changes on the blast injuries of the maxillary were analyzed by the LS-PrePost software.Result1.A three-dimensional solid model of human craniofacial bone was established.The geometric shape of the model was consistent with the entity.Anatomical structures were detailed,and the spatial position was accurate.2.A three-dimensional finite element model of human cranio-maxillofacial bone blast injury was established.The number of bone tissue and air units were 468319 and 157888,respectively,and the number of nodes was 112931 and 166979,respectively.3.Dynamically simulate the process of human maxillary injury under different loading conditions,and obtain the dynamic distribution figures of bone injury,stress cloud figures and strain cloud figures.The morphology of bone injury was similar to that of classic explosion injury.4.Under the three loading conditions,the peak of Von Mises stress was the highest at unit C of the low border of sutura zygomaticotemporalis,and the second highest at unit B of the front edge of sutura zygomaticofrontalis,but was the lowest at unit A of infraorbital margin of sutura zygomaticomaxillaris.The smallcross-section bone area was prone to high stress.This indicates that stress concentration is likely to occur in the smallcross-section bone area,and the high stress areas are consistent with the common fracture locations in clinical practice.Conclusion1.The computer inverse modeling method based on Mimics and Geomagic Studio software can establish a three-dimensional solid model of human craniofacial bone.The model has high degree of reduction,low time cost and wide application prospects.2.The HyperMesh and LS-DAYNA software can be used to establish the finite element model of blast injury,and it can effectively simulate the injury process under different loading conditions.The method can also display and analyze the whole simulation process in various ways.Therefore,this method can be used as a research tool to explore the biomechanical analysis of maxillary blast injuries.3.After the blast wave acts on the maxillofacial bone,stress convergence occurs in the small part of the bone cross section during stress transmission.It can provide an intuitive explanation for why fractures are more likely to occur in these areas.4.Blast distance and equivalent are important factors affecting the explosion damage.In addition,the effect of distance change on the severity of bone damage is more obvious than the equivalent change.