Structures Characters And Biomimetic Penetration Test Of Bull Shark Teeth

As a subject with a long research history,the penetration behavior is widespread in the military and civil fields.It focuses on the penetration process from the perspective of bionics,and studies the penetrating behavior,which helps to fully understand the characteristics of penetration and the penetration mechanism.Bionics is a new type of cross-discipline.It provides researchers with new research ideas and methods when solving problems such as penetrating,common friction and wear of cutting parts,and energy consumption.Bionics is adopted in this paper.The bull shark teeth are the subjects of research.Through the analysis of its dental biological characteristics,combined with the microscopic friction,wear characteristics and other studies,the excellent performance of the teeth during the predation process is explored.The application of bionic research results to the optimal design of penetrating components can provide beneficial attempts and explorations for effectively improving the penetrating ability of penetrating components and reducing the speed attenuation.The bull shark is the species with the highest biting force among all sharks.Its sharp mandibular teeth can pierce through the prey and firmly grasp the prey,the maxillary teeth cut the prey.This paper analyzes the microscopic structure,composition and friction and wear characteristics of the bull shark teeth,and finds that the high piercing cutting performance of bull shark teeth is related to its shape and structure.Using Reverse Engineering software to three-dimensional reconstruction of teeth,extract the characteristic curve,and fit the curve to get the bionic curve equation.Then,16 penetration models with 4 head angles and 4 outer contour curves were designed,the common type is used as the bionic models.Static and dynamic numerical simulation of penetrating models using finite element analysis software,the difference of mechanical properties and the relationship between the residual velocity and velocity loss during high-speed penetration were analyzed and compared.3D printing technology was used to process the penetrating model sample,and the model was used to conduct the soil penetration test using the electronic universal testing machine.The relationship between the penetration resistance and the penetration depth was determined.The results show that in the static analysis,when the same load is applied,the maximum equivalent stress of the bionic type 1 is smaller in the model with the head angle of 30° and 40° than that of the ordinary type,and the bionic type 3 is 50° and 60° in the head angle.In the model,the maximum equivalent stress is less than the ordinary type,but the difference in penetration performance between the models is small;In the dynamics analysis,under different penetration initial velocity and target plate material,the bionic type 1 has the largest remaining velocity in the head angles of 30° and 40°,the smallest velocity loss,and the best penetration performance.When the angle of the part is 50° and 60°,the bionic type 3 has the best penetration performance,and the bionic type 1 is better than the ordinary type;In the soil penetration test,when the penetration speed is 500 mm/s and the head angle is 30°,the bionic type 1 resistance is reduced by 12.5% compared to the normal type;head angle is 40°,bionic type 1 resistance is reduced by 16.2% compared to normal type;head angle is 50°,bionic type 3 resistance is 3.6% lower than normal type;head angle is 60°,bionic type 3 resistance is 8.53% lower than normal type.When the penetration rate was changed to 750mm/s and 1000mm/s respectively,the obtained conclusion was basically the same as that at 500mm/s.The bionic type 1 had the best penetration performance when the head angle was 30° and 40°,and the bionic type 3 was in the head.The minimum resistance is 50° and 60°.The above results show that the profile of the head of the penetrator has a certain influence on the penetration performance.This paper aims to improve the penetration performance of the penetrating part and reduce the speed attenuation.Bionic design provides new ideas and theoretical basis for the design of penetrating parts,which has important reference value.