The Coloration Mechanism Of Two Kinds Of Irreversible And Reversible Color-changing Beetles

The fore wings have keratinized as hard elytra whose area is equivalent to about half of the insect body, which have variety of fountions, preventing water evaporation, regulating body temperature, protecting body and membranous wings, reducing friction and working as waterproof after the long-term biological evolution and survival of the fittest. The surface of elytra shows biological coloration and characteristics that help beetle protect itself and attract mates so as to adapt to the environment, and that also provide an inspiration of designing bionic composite color change materials. In this paper, we use the elytras of irreversible color change of Harmonia axyridis Pallas and reversible color change of Dynastes tityus as the research object to investigate the mechanism of color change. The work provides the foundation for the designing bionic comoposite materials.In view of the two kinds of beetle with irreversible/ reversible color change, it firstly aims at researching the relationship between the elytra’s color, living habits and environment. To study the correlation between nanomechanical properties and color change of two kinds of irreversible/ reversible color change beetle, it is basic to investigate differences of nanomechanical properties of different color area selected by H. Pallas elytra and the change of nanomechanical property while D. tityus elytra doing reversible color change by the nano-indentation technique. We adopted Differential Thermal Analysis(DTA), Thermal Gravimetric Analysis(TGA) and hydrogen peroxide experiments to explore the effects of elytra composition on color change mechanism. We used SolidWorks software to build the coupling structure model based on data collected by elytra parameter of section structural and nanomechanical properties, then combining optical parameters acquired by optical analysis instrument to build optical structural model, finally carrying out optical simulation analysis according to the theory of thin film optics with MATLAB software to reveal the mechanisms of irreversible and reversible color change of two kinds of beetle.According to the correlation mechanisms between microstructure, nanomechanical properties, elytra composition and elytra irreversible/ reversible color change, this thesis applied Entomology, Materials Science and Optical testing, using nano-indentation technique, modern material testing technology and optical testing technology to research mechanism of color change composite materials and build theoretical foundation of bionic coupling color change composite materials design.