Study On The Macro-Micro Mechanical Properties Of Pangolin Scales And Its Impact Resistance Simulation

As a kind of ancient creatures, the pangolin survives on the earth as long as one hundred million years, the scales of Pangolin show outstanding mechanical properties in digging. Therefore, it is necessary to study the mechanical properties of the pangolin scales for understanding its mechanical characteristics, and providing guidance for the development of bionics.In this thesis, macroscopic MTS testing and nano-indentation testing have been used to get the basic mechanical properties of the Chinese pangolin scales, and the mechanical properties between transverse and longitudinal directions, and different layers have been compared. SEM, and 3D laser microscope also have been used to obtain the microstructure characteristics of the scales to interpret the macroscopic mechanical behavior. Besides, the impact response of pangolin scales is discussed by using finite element code, i. e, ABAQUS. Based on the mechanical testing, micro-structure observation and finite element simulation, it can be concluded that:(1) The pangolin scales exhibit good toughness, and they present lower elastic modulus, ultimate strength, and higher elongation after being soaked in water. The macroscopic mechanical properties of the pangolin scales in transverse direction are similar to that in the longitudinal one.(2) As a typical visco-elasto-plasticity material, the pangolin scales exhibit obvious ratcheting under the asymmetrical cyclic stressing, and this phenomenon is more obvious after being immersed in water.(3) The mechanical properties of the pangolin scales are similar in different parts and layers. The elastic modulus measured by nano-indentation testing is higher than that by macro-testing.(4) The pangolin scale is formed in a layer structure by overlapping and stacking micrometer-scale slices, and this unique structure is helpful to improve the toughness of the scales.(5) The finite element model of pangolin scales under impact loading was established by using ABAQUS, and the mechanical response has been discussed under impact loading. Normal impact simulation of pangolin scale shows better impact resistance than other angles. The impact resistance of double-layer pangolin scales is better than that the a single pangolin scale...