Acoustic metamaterial and wave control
Acoustic metamaterial is a kind of composites with designed microstructure. At macro scale, it has some odd equivalent properties like negative equivalent mass density, equivalent anisotropy density, negative equivalent modulus. Based on these interesting behaviors, acoustic metamaterial has potentials in low frequency sound absorption, super resolution imaging and wave control.
The main idea of wave control is manipulating wave propagation by designing anisotropic material properties distribution, which is hard to solve. In recent years, acoustic transform theory provided us a direct way to solve this problem. The theory is based on the fact that any acoustic function stays uniform under any curve transformation. And the acoustic media's properties deduced from transform method can only be achieved through acoustic metamaterial. We study the dynamic micromechanics model and microstructure design method of acoustic metamaterials. Besides, we also research in applications of acoustic metamaterials, such as acoustic super resolution imaging and invisible cloak.
Micromechanics method of composites and lattice materials
In micromechancis, building up connection between effective properties of inhomogeneous media and microstructure's geometry is fundamental to composites' design. Because of the well ratio of stiffness to mass, lattice materials are broadly applied in engineering. Meanwhile, lattice materials are highly designable. Many scholars introduced various kind of lattice materials with peculiar features, like negative poisson ratio materials, chiral lattice materials and pentamode materials. Our research is focusing on static and dynamic micromechancis method of composites and lattice materials, especially considering high order continuum media (micro polar media, Willis media), so that to depict the static and wave behavior more logically.
Vibration control of massive structure
Flexible structures have been broadly used in space engineering. The vibration behavior of these structures has great influence on the spacecraft's stability and safety. These flexible structures have features like low mass, large length-width ratio and complex geometry. Based on those facts, traditional theoretical methods are unable to depict the vibration behavior precisely, and the vibration is hard to control. Our research here is mainly focused on the vibration control theory of flexible structures based on wave motion theory. And establish the active/passive control strategies to absorb the reflection, then apply these to massive space structures.
Pattern control of microstructure
Lightweight membranes are broadly used in spacecraft, which are easy to buckle under force/heat load, and then have severe influence on the function of the structure. So it's meaningful to understand the relationship between macro/microstructure and external stimuli. We study the structure response of membrane under multiphysics effect. And design inhomogeneous materials to achieve effective control of the structure. Then apply them to massive membrane antenna and other fields like micro electronics and biomedicine.
Particle behavior in electric field
To ensure the normality of searching activities on the moon surface, it's necessary to keep the detector out of moon dust. The method to achieve this should be lightweight and has low energy consumption, and also can adapt to the environment on the moon surface. Here we use electromagnetic field to control dust particles, and based on this to develop a new technology to remove dust from detector.