Measurement Of Tissue Mechanics And Contact Angle Characteristics Of Puffer Skin And Its Application In Bionic Drag Reduction

The comprehensive national strength of the country is closely related to the marine economy and national defense,and underwater vehicles,such as submarines and cruise ships,play a very important role in this development strategy.Therefore,it is necessary to reduce the resistance of the underwater vehicle in the process of moving by some means.Inspired by the migratory characteristics of puffer when swimming in the water,a series of experiments were carried out to test the biomechanical properties of the puffer skin based on its skin structure and biomechanics theory,and selected the puffer skin as the research object,and carried out a series of experiments on the biomechanical properties of the puffer skin.The specific contents of the study are as follows:(1)The puffer skin was subjected to quasi-static tension,loading-unloading,stress relaxation,creep,etc.The distribution of stress,strain and time and the distribution of stress,strain and time in the puffer skin were obtained.The Mooney-Rivlin and Zener equations were used to construct the quasi-static tensile and relaxation constitutive relationships in different positions(puffer dorsal skin and abdominal skin)and in different directions(cross-section and longitudinal direction)of the puffer skin.It provides support for the further study of biomechanical properties of the puffer skin and its practical application.(2)The contact angle of the puffer dorsal and abdominal skin was measured on the Theta lite contact angle measuring instrument.In order to reduce the experimental error,three points were taken on the surface of the samples measured on the puffer skin,and the average values were measured three times at each sampling point position in order to reduce the experimental error.The main factors affecting the contact angle were the surface mucus,bone spines,wetting degree and the volume of droplets in the skin samples of puffer skin.According to the results of contact angle measurement,the influence degree of each factor on the contact angle value of puffer skin was analyzed,and the variation rule of contact angle under these factors was summarized.Finally,the drag reduction mechanism of puffer's skin surface mucus was expounded.(3)Based on the experimental data of the puffer skin,the material properties of different positions(puffer dorsal skin and abdominal skin)and direction(cross-section and longitudinal direction)of the puffer skin were analyzed by fluid-solid coupling numerical simulation method.The effects of different positions and directions of puffer skin on the drag reduction performance of plate members and its mechanism are studied,and other rigid materials are selected as reference to compare the drag reduction effect of puffer skin.The effects of different positions and directions on drag reduction of puffer skin were analyzed macroscopically.The results showed that the drag reduction effect of longitudinal direction material parameters of puffer abdominal skin was the best,reached 5.45%.(4)The puffer abdominal skin longitudinal direction material with the best drag reduction effect was selected to carry out the fluid-solid process under different thickness and different velocity of flow.The coupling analysis shows that the greater the thickness is,the better the drag reduction effect is.The variation law of drag reduction rate is also different under different range of water flow velocity change.Finally,the local drag reduction law of fluid-consolidation coupling region under the longitudinal direction material parameters of the puffer skin is discussed from the microscopic point of view,finally,and the drag reduction mechanism of flexible skin is discussed.