| High energy explosive weapons are widely used in modern warfare.However,the maxillofacial blast injury is relatively high in the body explosion injury due to its prominent position and lack of protection.The treatment of maxillofacial blast injury is difficult,and the injury and mortality rate is very high.Therefore,it is of great significance to establish the model of human maxillofacial explosion injury and analyze the injury mechanism,injury characteristics,protection and treatment points of maxillofacial explosive injury.The three-dimensional finite element method(FEM)can analyze the complex mechanical changes between and within objects,and predict the effect of mechanical action.It is an important method for the simulation of maxillofacial blast injury.However,this method has some limitations in the study of maxillofacial soft and hard tissue injury caused by blast wave,which is manifested in simulation failure and deformation.Smoothed particle hydrodynamics(SPH)is a meshless simulation method,which can make up for the deficiency of 3D finite element method.In the battlefield environment,the modern combat protective helmet has the function of bulletproof and explosion-proof,which plays an important role in protecting craniomaxillofacial explosive injury.The biomechanical simulation study on the protective ability of combat protective helmet under blast injury is of great significance for further understanding the protection mechanism of helmet on maxillofacial region,understanding the limitation of protection,and how to further improve and improve the protection effect.Therefore,the purpose of this study is to: 1.Establish FEM of explosive injury in the maxillofacial region,and analyze the process and biomechanical characteristics of the model;2.The application of SPH method in the study of explosion injury in maxillofacial region provides a new method for the study of explosion injury model;3.The protective effect and mechanism of helmets on explosive injury in maxillofacial region;Methods and results1.The FEM including human mandible cortex,cancellous bone,skin and masseter muscle was established based on CT and MRI data.The model was imported into the finite element preprocessing software ANSA.The FEM of explosion injury of mandible was established by combining tetrahedron and hexahedron elements.The model includes 1238910 cells and 1176338 nodes.The results show that the FEM of explosion injury of mandible is similar to the human anatomical structure,with small loss of details and reasonable division of finite element cells,which can meet the biomechanical research of explosion injury of human.2.The FEM of explosion injury of mandible was set up to simulate the dynamic injury process of skin,masseter muscle and mandible in 9 groups of different TNT explosive(600mg,800 mg,1000mg)and different explosion distance(3cm,5cm,10cm).The results show that the FEM is reasonable and reliable,which can predict the process of maxillofacial explosive injury,and can satisfy the biomechanical analysis of explosive injury.3.Through the FEM results,the simulation process of explosion injury in human maxillofacial region,Von Mises stress and effective strain are systematically analyzed.The results showed that:(1)Von Mises stress and strain can be used as an index to evaluate the severity of mandible tissue injury,and as an analysis of tissue necrosis area after explosive injury of skin and muscle soft tissue,so as to guide the early debridement of soft tissue.(2)Under the same injury condition,the degree of mandible caused by blast wave is more serious than that of skin and muscle soft tissue(3)In addition to the fracture of the mandible angle caused by the blast wave,the stress can also be transmitted to the condyle and sigmoid notch areas of the mandible,resulting in the formation of high stress and high strain areas in these areas,thus forming the fracture.4.A three-dimensional model of explosive injury of mandible was established by SPH,and the effectiveness of the model in the simulation of explosive injury of mandible was studied.The results show that the structure of the model is similar to that of human anatomy,with less detail loss,and the results are close to the FEM.The SPH has significant advantages over the FEM in solving large deformation,crack growth,contact penetration,explosive impact and other aspects in the study of explosive injury in the maxillofacial region.5.The QGF11 helmet is successfully established by the FEM.The model includes the structure of helmet body,flexible lining and lace up,and is assembled with the model of explosion injury in human maxillofacial region,thus the model of explosion injury in maxillofacial region of helmet is obtained.The results show that the model is similar to the real helmet with less detail loss.It can be used to study the protection of the helmet against the explosion injury in the maxillofacial region.6.The explosion injury of mandible was set up to simulate the dynamic damage process of skin,masseter muscle and mandible of different explosion distances(3cm,5cm,10cm)by TNT(1000mg),and stress-strain analysis.The results showed that the degree of soft and hard tissue explosion injury decreased after wearing the helmet,especially in the experimental group of 5cm-1000 mg.The result can be used to guide the improvement of helmets,so as to increase the protection of explosion injury.Conclusions1.The FEM of explosive injury can be used to analyze the process and biomechanics of soft and hard tissues in maxillofacial region.The model can be used to guide the treatment and protection of explosive injury in maxillofacial region.2.Compared with the FEM,the SPH has a significant advantage in the study of blast injury,which can provide a new method for the research of maxillofacial blast injury.3.The results show that the protective helmets can protect blast injury of maxillofacial region,but not to the exposed parts.The results can be used to guide the improvement of modern combat helmets,so as to increase the protection of maxillofacial explosion injury. |
PDF Full Text Request