An acoustic negative bulk modulus metamaterial based on the concept of expansion chambers is proposed. It is shown that addition of a neck region to an ordinary expansion chamber improves its transmission loss characteristics at low frequencies and the resulting structure displays a negative bulk modulus behavior. Additionally, membrane based metamaterials are analyzed. Using FEM, the negative ...

We study theoretically the bulk modulus (inverse of the compressibility) of a suspension of charged objects (macro-ions), making use of a cell model to account for the finite density of macro-ions. The diffuse layer of charged micro-species around a macro-ion is described by a generic local density functional theory. Within this general framework, we obtain the condition for a positive bulk mod...

Effects of pressure on lattice parameters and molar volume of diaspore were studied to 25.5 GPa at 300 K by polycrystailine X-ray diffraction techniques. The pressure-volume data fit with a second-order Birch-Murnaghan equation of state give a bulk modulus K0 = 167.5 GPa. The bulk modulus is twice the previously reported, but unsubstantiated, value of K0 = 85 GPa by Ruoff and Vanderborgh [Phys....

It is shown that the shoving model expression for the average relaxation time of viscous liquids, according to which the activation energy is proportional to the instantaneous shear modulus, follows largely from a classical "landscape" estimation of barrier heights from curvature at energy minima. Although the activation energy in this reasoning involves both instantaneous bulk and shear moduli...

With the discovery of hearing disorders caused by mutations in proteins expressed in the tectorial membrane (TM), the importance of the TM in cochlear mechanics has never been clearer. However, the exact role of the TM in cochlear mechanics remains a mystery. In this thesis, I have investigated material properties of two mouse models of genetic hearing disorders that affect proteins found in th...

We demonstrate that the compressibility of cubic fluorite-structure CeO2 nanocrystals s10 nmd increases at pressures above ,20 GPa. At ambient pressure, CeO2 nanocrystals exhibit larger cell parameters than micro-sized samples, and initially exhibit a higher bulk modulus of 328s12d GPa. However, above 20 GPa, the bulk modulus is reduced to 230s10d GPa. Thus, a critical pressure of ,20 GPa was d...

Elastic properties of carbon nanotubes and nanoropes are investigated using an empirical force-constant model. For single and multi-wall nanotubes the elastic moduli are shown to be insensitive to details of the structure such as the helicity, the tube radius and the number of layers. The tensile Young’s modulus and the torsion shear modulus calculated are comparable to that of the diamond, whi...

Bulk metallic glasses--formed by supercooling the liquid state of certain metallic alloys--have potentially superior mechanical properties to crystalline materials. Here, we report a Co(43)Fe(20)Ta(5.5)B(31.5) glassy alloy exhibiting ultrahigh fracture strength of 5,185 MPa, high Young's modulus of 268 GPa, high specific strength of 6.0 x 10(5) Nm kg(-1) and high specific Young's modulus of 31 ...

Lattice constant, density, total energy, cohesive energy, bulk modulus, microhardness, Young modulus, speed of sound, energy of acoustic phonons, plasmon energy and vibrational energy, for diamond, silicon, germanium, and gray tin, all have been calculated and studied when compression stress is exerted. It is found that most of them increase with pressure except the lattice constant which decre...