Zhang Junqiu

Erosion resistance of bionic functional surfaces inspired from desert scorpions.

In this paper, a bionic method is presented to improve the erosion resistance of machine components. Desert scorpion (Androctonus australis) is a typical animal living in sandy deserts, and may face erosive action of blowing sand at a high speed. Based on the idea of bionics and biologic experimental techniques, the mechanisms of the sand erosion resistance of desert scorpion were investigated. Results showed that the desert scorpions used special microtextures such as bumps and grooves to construct the functional surfaces to achieve the erosion resistance. In order to understand the erosion resistance mechanisms of such functional surfaces, the combination of computational and experimental research were carried out in this paper. The Computational Fluid Dynamics (CFD) method was applied to predict the erosion performance of the bionic functional surfaces. The result demonstrated that the microtextured surfaces exhibited better erosion resistance than the smooth surfaces. The further erosion tests indicated that the groove surfaces exhibited better erosion performance at 30° injection angle. In order to determine the effect of the groove dimensions on the erosion resistance, regression analysis of orthogonal multinomials was also performed under a certain erosion condition, and the regression equation between the erosion rate and groove distance, width, and height was established.

Research progress of mechanical properties of natural wood and bamboo fiber composites and their biomimetics

Natural bio-fiber composites have the characteristics of simple elements and sophisticated structure, superior mechanical properties of high strength, high toughness and low coefficient of friction, and are the inspirational sources for the design of new materials. Biomimetic fiber composites have been widely used in modern industry. At present, studies of learning from the natural biological material structure-functional characteristics to manufacturing biomimetic structure—Functional integration material have originated lots of results, such as imitating wood porous ceramic material, imitating shell multi-layer composite materials and imitating bone porous scaffolds, etc. However, a lot of problems still exist, such as fiber is brittle and easy to be pulled out, the size selection of the whisker is difficult, the choice of ceramic matrix composite toughening methods is difficult, etc. To guide advanced biomimetic materials designs, it is important to reveal the relationships between the distribution, angle and density of cellulose, structure and binding mode of interface and the mechanical and frictional properties of the biological fiber composites. Wood and bamboo are the most common natural biological fiber composites which have excellent mechanical properties. They have been widely used in a variety of traditional architectural and ship parts. In this manuscript, recent researches on the mechanical properties of the wood and bamboo as the typical representatives of the natural biological fiber composites have been reviewed. The biomimetic composites of natural fiber materials have been briefly summarized. This tentative review might provide a reference for the design and preparation of biomimetic high strength, wear-resistant fiber composites. Trees and bamboo with excellent tribological properties relies not only on its internal structure, but also on its biological activity. If purely from a mechanical point of view to achieve the purpose of the bionic, it is difficult to obtain satisfactory results. Modern fiber composites in the rapid development process, often there is a big fiber brittle, difficult to interface design, easy to pull the fibers lead to enhanced failure whisker size selection difficult to choose the difficulty of ceramic matrix composites toughened approach the problem. Therefore, the application of bionic fiber reinforced composites toughened functional design principle, simulate biological fiber composite materials and structures excellent interface characteristics, is expected to further address the interface of chemical and physical properties of stability and strength of fiber composites tough problem, has important academic significance and application value.