Rheological-dynamical model of concrete and its application on RC beams

Mechanics of Time-Dependent Materials - An improved analytical model based on rheological-dynamical analogy (RDA) is briefly explained and used for the analysis of concrete cylinders under...     

Plasmonic focusing reduces ensemble linewidth of silver-coated gold nanorods

Silver coating gold nanorods reduces the ensemble plasmon line width by changing the relation connecting particle shape and plasmon resonance wavelength. This change, we term "plasmonic focusing", leads to less variation of resonance wavelengths for the same particle size distribution. We also find smaller single particle linewidth comparing resonances at the same wavelength but show that this does not contribute to the ensemble linewidth narrowing.     

Strain Rate Insensitivity of Damage-Induced Surface Area in M30 and JA2 gun propellants

Uniaxial compression tests are conducted on single-grain seven-perforated specimens of M30 and JA2 gun propellant using the U.S. Army's high rate servohydraulic test apparatus in order to investigate the effects of strain rate, temperature, and percent axial strain on the combustion characteristics (apparent burn rate and pressurization rate) of the propellants. At room temperature M30 primarily deforms by macroscopic fracture and JA2 deforms by macroscopic flow. The total number of tests (sixteen) is minimized by designing the experimental program according to a 2⁴ statistical design strategy. The single grains of deformed propellant are then burned in a newly designed 7.8-cm³ mini closed-bomb and plots of pressure, pressurization rate and surface area ratio versus time, and apparent burning rate versus pressure are compared with baseline results for the undeformed propellant specimens. The apparent burn rates of damaged M30 propellant vary considerably and the degree of damage induced surface area approaches six times that of the undeformed baseline M30 specimens. The apparent burn rates of JA2 are relatively unaffected by the induced deformation. Results indicate that the apparent burn rate of JA2 at 20 MPa is primarily dependent on the deformation temperature, yet the apparent burn rate of M30 at 20 MPa is dependent primarily on percent axial specimen strain. The apparent burn rates for these propellants are relatively insensitive to the deformation strain rate over the range 10⁻² to 100 sec⁻¹.