Hydrostatic equilibrium

About: Hydrostatic equilibrium is a research topic. Over the lifetime, 2451 publications have been published within this topic receiving 62172 citations.

Dynamic response of ground supported rectangular water tanks to earthquake excitation

Abstract: This study investigates an idealized ground supported reinforced concrete rectangular water tank under earthquake excitation. A linear three-dimensional finite element analysis and SAP2000 software have been used to predict tank response. The variable analysis parameters considered are the aspect ratio (tank height to length ratio) and tank water level, while the tank wall thickness is taken as a constant. The convective and impulsive masses are also represented by spring-mass model in the time history analysis for El-Centro earthquake ground motion record. Five tank models with a capacity of 216, 288, 360, 432 and 504 m 3 were developed and analyzed for hydrodynamic and hydrostatic effects. In general the results show that, there is a smooth increase in the moment and displacement of both hydrostatic and hydrodynamic analysis with a decrease in aspect ratio. The top displacement and moment for the hydrodynamic effects are greater than the hydrostatic results and it is observed that the maximum hydrodynamic moment is 91.3% higher than the corresponding maximum hydrostatic moment. Likewise the displacement obtained from hydrodynamic analysis is 63.58% more than the corresponding hydrostatic value. Keywords: Hydrodynamic effect, Convective and Impulsive, Rectangular tanks, Finite Element Models, Time history, SAP2000, Ethiopia

Correction to: Thermal behavior of an improved face‑grinding spindle: water‑lubricated hydrostatic thrust bearing decreases temperature rise and increases axial stiffness

Abstract: Axial thermal deformation and axial stiffness are the leading technical indicators affecting face-grinding spindle manufacturing accuracy. However, the face-grinding spindle supported by rolling bearings lubricated with grease has a disadvantage regarding temperature rise, axial stiffness, and rotational accuracy. To overcome this issue, this study proposes a novel face-grinding spindle supported by combined bearings, which include a water-lubricated hydrostatic thrust bearing and two rolling bearings with an oil-air lubrication system. The thermal model for the proposed face-grinding spindle is established, and the spindle thermal behavior is analyzed systematically. An experimental prototype of the face-grinding spindle is developed, and the temperature rise of the spindle is detected to verify the thermal model. The result shows that the temperature rise of the proposed spindle can be decreased by the use of the water-lubricated hydrostatic thrust bearing. A comparative study between the two types of spindles shows that the proposed face-grinding spindle with the combined support has the technical advantage of low-temperature rise, high axial stiffness, and high rotation accuracy.

On crack nucleation and propagation in elastomers: I. In situ optical and x-ray experimental observations

Abstract: Abstract This article presents the results of an investigationof crack nucleation and propagation in atransparent polydimenthylsiloxane (PDMS) elastomer.The main objective of the investigation is to characterizequantitatively the evolution of crack nucleationand propagation behavior not just through the usualmacroscopic load and displacement data, but with synchronizedoptical images at high spatial and adequatetemporal resolution that will resolve the evolution ofthe failure processes. This is augmented with x-ray computedtomography (CT) scans to characterize the threedimensionalgeometry of the cracks nucleated in the interiorof the elastomer.Towards this goal, we reproduce the classical pokerchipexperiment of Gent and Lindley (1959) in whichthe specimen’s diameter-to-thickness ratio is varied overa broad range to cover crack nucleation, propagation,and their coalescence. These experiments are performedon transparent PDMS with different compositions, firstin a specially built loading machine that is fitted witha high magnification microscopic camera that permitsthe measurement of the load while simultaneously providingimages of the specimen configuration and subsequentlyin an apparatus built for in situ observationsusing an x-ray CT scanning system.These experiments reveal that nucleation of multiplemicrocracks dominates when the diameter-to-thicknessaspect ratio α is sufficiently large, because the incompressibilityof the material induces substantial, nearlyuniform hydrostatic tension in the specimen. In contrast, specimens with smaller aspect ratio tend to nucleatefewer cracks, and are dominated by the growth ofthese cracks. At even smaller α, the hydrostatic stress issignificantly lowered and failure is dominated by surfaceflaws. The three-dimensional geometry, and the spatialdistribution of the nucleated cracks were evaluated usingoptical microscopy and x-ray CT scans. This revealedcracks of three different shapes, one of which wasconfined in a layer near to the upper or bottom boundaryof the poker-chip, another was across the thickness,but with a tilt relative to the axis of the specimen, andthe last was propagating along the radial direction.