Appraisal Rabbit Liver Injury Based Upon Plastic Composite Materials’ Deformatin To Impact

The liver injury usually occurs and cause of death in traffic accident. Appraisal of liverinjury is an important foundation for vehicle safety design and reducing casualties. Atpresent, the vehicle’s safety assessment is using dummy III, which is a simplified physicalmodel based on early acceleration injury of cadaver, but in actual traffic accidents, liverinjuries of driver and passenger are mostly deceleration injury. The acceleration injury isclosely related to the extrusion and maximum deformation speed, while the decelerationinjury belongs to the inertia injury; they are in significant differences. For this reason,asdummy III is difficult to assess liver injury, now we need to seek a new assessment methodfor liver injury.It is difficult to know the parameters when liver suffered injury, because it is locatedinside the abdominal wall. In traffic accident reconstruction, the deformation of vehicle notonly used to analysis the direction of collision force, but also can calculate collision energy.Samely, in the field of solid mechanics of materials, it can study the forces acting anddeformation energy by the material deformation. According to those theories, this study isto establish an appraisal method of rabbit liver injury that can be based upon thedeformation and the impact of plastic composite materials. For this, it has developed aplastic composite material, perceived the force direction by deformation characteristics,analyzed the rabbit liver injuries energy by the size of the deformation.The main studying methods and results are as follows:1. Aplastic composite material was developed.Instron8871was used to measure mechanical properties of materials; ultimatedeformation, deformation resistance and crack shape were as the material plasticity index; aplastic composite material was filtered which composited potassium stearate, paraffinliquidand epoxy novolae resin, with a weight ratio of0.78/0.22/0.04. It stired only3hoursat room temperature, condition which was simple, convenient, economical, easy to control and renewable use. The material was made of tiny uniform flaky, and flakyslip betweeneachothermakes this material of perfect plastic property. The material has differentstrengthening characteristics compared with power strengthening model, and it was moreaccurate when using logarithmic strengthening model to describe.2. An accurate digital model of plastic composite material was established.Flash slive rnot only increased to high reflector but also prevented laser penetrating ofFaro Laser Scanner Fonton120. Coating flash sliver was an efficient method to obtainhigh-quality point clouds.A high-quality digital model was a foundation for analyzing theforce direction and calculating the deformation of the plastic composite material.3. The relationship between volume deformation and impact energy was established.Using finite element simulation and experimental research method, we created therelationship among impact impulse, volume deformation and mass.The formula was，and the correlation coefficients were2Based on the momentum theorem and the conservation law, the impact energy wascaculated.This experiment established a method of calculation of impact energy bydeformation.4. The energy of rabbit liver injury was analyzed..Under the same impact velocity, rabbitA and rabbit B whoseliver was replaced byspherical plastic composite material were impacttoreproduce deceleration injury model, theinjury characteristics included three points,(1) The impact conditions inclunding: theimpact speed waveform was approximate reduction trapezoidal wave, and the peak is about22.65g (g was acceleration of gravity); the impact speedswere in range from35.0km/h to41.3km/h, in other words, the drop heights were in range from4.82m to6.70m. Underthis impact conditions, with the increase of impact velocity, the corresponding injury energyincreased from0.286J to1.299J, and the severity of rabbit liver injury increased from minorto severe.(2)The feature of the deformation of spherical plastic composite material afterimpact verified the main cause of rabbit liver deceleration injury is the inertia.(3) When theimpact velocity less than40km/h, less than22%of the external impact energy wastransfered to the liver through thoracic cavity and abdominal wall, thus the thoracic cavityand abdominal wall protective effect for liver was quantified.Inconclusion, first of all, we have prepared an plastic composite material, which can sense the force direction, vulnerant shape, manner of causing, and can be used to calculatethe impact energy,which has put forward a kind of new plastic reinforcement mechanism,ans enriched the theory of plastic mechanics theory. Next, we have verified that the maincause of deceleration injury of rabbit liver is the inertia. After that have we taken the lead inestablishing a appraisal method of rabbit liver injury based upon the plastic compositematerials’ deformatin and the impact energy. The method can be used to appraise thedeceleration injury and acceleration injury. The method has made the study of organ injurymechanism extends form out to in the chest and abdomen, opened a door to abtain theabdominal organ injury energy, and quantificated the protection effect of the chest andabdominal wall.Due to the time limit, the above work is only a preliminary study in the field ofabdominal organ injury,and is still exist some disadvantages. For example, Plasticdeformation is a results not a process. It used spherical plastic composite material model toreplace the rabbit liver, not with the same shape. Therefore, this methed need to be studiedin-depth and to improve in the future work.