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Gary R Consolazio – 1st expert on this subject based on the ideXlab platform
calculation method for quantifying axial and roll stiffnesses of rectangular steel reinforced elastomeric bridge Bearing PadsTransportation Research Record, 2013Co-Authors: Zachary S Harper, Gary R ConsolazioAbstract:
Accurate estimates of Bearing stiffnesses are often necessary for bridge design and construction calculations. In the case of steel-reinforced elastomeric Bearing Pads, the compression stiffness or roll stiffness is sometimes difficult to estimate because of complex deformations of the elastomer. A method of numerical analysis for estimating the axial and roll stiffnesses of Bearing Pads is presented. To validate the axial calculation method, experimental compression tests were performed on pad specimens constructed in accordance with Florida design standards. A method for calculating roll stiffness is also presented in which the pad is modeled as a grillage of compression-only axial springs. The grillage method was partially derived from roll stiffness data measured in a separate experimental study. The grillage method was demonstrated to accurately capture both the nonlinear moment-rotation behavior caused by liftoff of the girder from the pad and the observed sensitivity of roll stiffness to initial co…
Kristian Tonder – 2nd expert on this subject based on the ideXlab platform
vibrations in spring supported Bearing Pads due to non contacting roughnessesWear, 1999Co-Authors: Kristian TonderAbstract:
The paper addresses vibration phenomena associated with the changes in the combined roughness distribution that may occur when there is roughness present on both surfaces of a Bearing. The study is performed by solving a modified Reynolds equation expressing roughness effects. The load may thus be generated numerically in terms of surface roughness parameters. It is demonstrated that the load carrying capacity may change considerably under these circumstances. This is shown to have a considerable influence on the net film thickness and may create film thickness fluctuations, particularly for transversely oriented roughness. It is concluded that the matter of surface roughness may be important if a very steady motion is required, particularly in the case of very thin films. It is also shown that the effect sometimes may be beneficial due to a resulting gain in mean film thickness.
I. A. Grishin – 3rd expert on this subject based on the ideXlab platform
Axial Thrust Balancing in High-Temperature Cylinders of Steam Turbines during Transients in Combined-Cycle UnitsThermal Engineering, 2019Co-Authors: Yu. A. Radin, I. A. GrishinAbstract:
The effect of magnitude and direction of the axial thrust during steam turbine transients on the starting technology is investigated. The behavior of the axial thrust during start-up of a steam turbine with a combined high/intermediate pressure cylinder operating in a single-bypass or two-bypass thermal cycle is presented. At different stages of start-up, varying steam pressure at the turbine inlet and in its flow path can result in a change in the temperature of thrust Bearing Pads and the magnitude and direction of the axial thrust acting on them. During start-ups with a two-bypass thermal scheme for steam admission to the turbine and its rotor acceleration, connection of the steam turbine generator to a grid and its initial loading are performed with steam supply through intermediate pressure-control valves. In this case, the high-pressure cylinder (HPC) is under “negative pressure” or “countercurrent” conditions passing steam from the exhaust via the bypasses of the check valves in the “cold” reheat steam lines and removing this steam to the condenser via the drains of high-pressure crossover pipelines and from the high-pressure cylinder casing. Connection of the turbine HPC for normal steam supply and change-over to the once-through scheme of steam admission to the turbine are carried out after connection of the turbine generator to the grid and initial loading of the turbine by partial opening of the HP control valve and full opening of the intermediate pressure (IP) control valves. At the same time, the valves of quick-acting pressure-reducing and cooling units (QAPRCU) BROU-1 and BROU-2 are closed to maintain the specified high and intermediate pressure of steam upstream from them. These process operations change the axial thrust acting on the thrust Bearing Pads with a corresponding change in the pad temperature. The effect of variable axial thrust on the steam turbine maneuverability is examined. Methods are proposed for balancing the axial thrust during start-ups of steam turbines in combined-cycle units having different thermal schemes.