Collapse of conical cavities in aluminium metal under shock wave impact

Under shock wave impact the conical free surface of the metal collapses and a metallic jet with a velocity exceeding 10 km/s is squirted out of the metallic target. Variation in the jet tip velocity when the cavity half angle ranges from 60 down to 7.5° has been studied over three different shock pressures. The jet velocity has been found to increase with the decrease in the angle of the conical free surface and as the angle approaches zero the jet tip velocity attains a value near to the limit set by hydrodynamic theory for non-compressible fluids. The effect of aerodynamic drag on this type of jet has been studied and it has been found that the jet formed by the collapse of a small angle conical cavity quickly slows down while travelling in air, whereas the jet coming out of large angle cavity suffers a small retardation. Theoretical explanation and experimental evidence in support of this fact are also presented.     

The effect of temperature and vibration on emulsion stability of mayonnaise in two different package types

Mayonnaise in two different packages was compared for its susceptibility to vibration-induced breakdown. The researchers investigated the effect of truck vibration on emulsion stability and compared two different package systems. The containers were 32 oz glass and 32 oz polyethylene terephthalate (PET). Mayonnaise was conditioned at three different temperatures (40°, 72° and 100 °F), for three time periods (21, 26 and 36 days), and vibrated at normal and worst-case transportation g levels. Emulsion stability was quantified by specific gravity, percentage of surface oil, and qualitatively rated by a visual pass/fail test. The specific gravity measure positively correlated to surface oiling. Glass containers showed a higher rate of emulsion failure at the worst-case vibration levels. No consistent difference in emulsion breakdown was found between plastic and glass at the normal transportation g levels.     

Hysteresis and bifurcations in the classical model of generator

The single machine operating onto an infinite bus is analyzed for its nonlinear dynamics using the classical model. Many aspects of limit cycle oscillations, bifurcation, and hysteresis in the system are brought to attention that were not known in the context of a power generator. A parameter graph that determines the nature of the dynamics for a given mechanical power at a given damping coefficient of the rotor is provided which helps determine the precise parameter values where hysteresis effects are to be expected.     

Experimental investigation into tool aging effect in ball end magnetorheological finishing

The International Journal of Advanced Manufacturing Technology - Magnetorheological (MR) finishing is a smart finishing processes applied to a variety of applications. In the present work, an...     

Effect of Dopants and Sintering Method on the Properties of Ceria-Based Electrolytes for IT-SOFCs Applications

Doped and co-doped ceria ceramics are used as electrolyte materials in solid oxide fuel cells. In this work, ceria-based oxides, Ce_0.90Gd_0.06Y_0.02M_0.02O_2?δ (M?=?Ca, Fe, La, and Sr) were prepared by conventional as well as microwave processing from the precursors prepared by the mixed oxide method. The consolidated calcined powders in pellet form were sintered in microwave energy at 1400°C for 20 min and in an electric furnace of IR radiation at 1400°C for 6 h. The x-ray diffraction analysis confirmed that all the compositions were crystallized into a cubic fluorite structure. Surface morphology of the sintered products was studied using scanning electron microscopy and the microhardness was investigated using the Vickers hardness test. The comparative results analysis shows that the microwave-sintered samples have uniform grain growth, higher density and higher microhardness than the corresponding conventionally sintered products. The microwave-sintered sample of composition Ce_0.90Gd_0.06Y_0.02Sr_0.02O_2?δ was found to have the highest microhardness among the four compositions due to its high density and smallest grain size.     

Producing High-Quality Titanium Alloy by a Cost-Effective Route Combining Fast Heating and Hot Processing

Powder metallurgy is a very attractive method for producing titanium alloys, which can be near-net-shape formed and have freedom in composition selection. However, applications are still limited due to product affordability. In this paper, we will discuss a possible cost-effective route, combining fast heating and hot processing, to produce titanium alloys with similar or even better mechanical properties than that of ingot metallurgy titanium alloys. Two titanium alloys, Ti-5Al-5V-5Mo-3Cr (Ti-5553) and Ti-5Fe, were successfully produced from HDH titanium powder and other master alloy powders using the proposed processing route. The effect of the processing route on microstructural variation and mechanical properties have been discussed.