Microstructural Design for Stress Wave Energy Management
Final technical rept. 1 Mar 2009-30 Sep 2012
CALIFORNIA UNIV SAN DIEGO LA JOLLA CENTER OF EXCELLENCE FOR ADVANCED MATERIALS
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The objective of this research program is controlling wave propagation in solids by meticulous design of the microstructure. We have established the concept of managing the essential characteristics of propagating stress waves including the wave travel direction phase planes and energy flux, stress tensor polarization, amplitude and attenuation, and inherent mode of energy pressure or shear. The approach to achieve such control is to design the heterogeneous microstructure of at the medium at microscopic level, thereby producing highly anisotropic and essentially homogenous elastic properties at the wavelength of interest, which are much larger than microstructural length scale. We have implemented the smooth change of elastic anisotropy to guide stress waves within a material, which was verified experimentally by judicious fabrication of a glass fiber reinforced composite. Furthermore, the abrupt change of elastic anisotropy creates an interface that enables us to control the wave scattering transmission and reflection as well as the mode of stress-wave energy pressure and shear. Specifically, a significant portion of the energy of impinging pressure waves can be transferred into shear waves. Then, we have integrated these methods with conventional mechanisms for shear dissipation i.e. viscoelasticity to control the amplitude, energy, and direction of propagating stress-waves in a multilayered structure.
- Laminates and Composite Materials