1,354,827 research outputs found
Analysis and design of pipe ramming installations
No full textFinal report -- Appendices A-D -- Appendix E -- Appendices F-M.This archived document is maintained by the Oregon State Library as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Title from PDF title page (viewed on June 5, 2015)."FHWA-OR-RD-XX"--Technical report documentation page.Includes bibliographical references (pages 245-254).Sponsored by Oregon Department of Transportation, Research Section; Federal Highway Administration SPR 710Mode of access: Internet from the Oregon Government Publications Collection.Text in English.Final repor
TOWARDS AUTOMATION OF ALUMINUM CELL RAMMING PROCESS
No full textNewly installed cathode blocks in an aluminium reduction cell, expand due to a rapid increase of temperature when passing a high current at the start-up of the cell. High thermal stresses may result if cathode blocks are lined without gaps, and this can lead to cracking of the cathodes and failure of the cell. On the other hand, leaving gaps would cause failure due to molten metal infiltration in the gaps. To overcome these problems carbon-based ramming material is used to fill these gaps. Currently ‘Filling’ is carried out manually or partially automated, but this needs to be fully automated in line with Industry 4.0. Automation here means the making of an apparatus, a process, or a system to operate with minimum inputs from humans and produce consistent filling of the ramming paste. The main objective of this project was to establish the needed characteristics of ramming paste under different conditions so that one can make decisions to optimize the life of the carbon paste in the cell while designing the automatic system. Experimental analysis was carried out to visualize and investigate the manual compaction of ramming paste in the gaps and identify forms and defects after the compaction. Building on this, characterization of ramming paste was carried out under different conditions by varying applied pressure. At room temperature, it had the ability to bond and solidify under pressure with increasing young’s modulus value as pressure increases. But it was observed that over-compaction initiated internal cracks in the solidified sample. Then, characterization was carried out by varying the baking temperature, so blocks were fabricated to be heated to different temperatures and then investigate their behaviours, the baking temperatures were from 200˚C to 600˚C. The achieved yield strength of 200˚C was high however similar strength was achieved at room temperature for unbaked samples as well, on the other hand, it was observed that the higher the temperature with the presence of oxygen the more fragile the ramming paste became. Further, to achieve a consistent flow of the ramming paste into the filling, the Principle of Fused Deposition Modelling was tested to extrude ramming paste using a nozzle with different nozzle profiles and various applied loads. This set of experiments concluded that ramming paste cannot be extruded using a nozzle as it gets compacted at the nozzle exit and compaction builds up on the top layers. The paste does not flow because of its strong bonding nature and the resulting consolidation under pressure. Based on the findings a machine was designed and built to extrude ramming paste using a two-stage process comprising of, firstly a screw conveyor to positively convey the material and secondly a roller to compact the material coming out from the screw conveyor. Test runs were carried out with the machine and the results show that the machine can produce ramming paste flow, at the desired density in a consistent fashion. Based on the findings of this research and the prototype machine, industry scale machines automating the ‘Aluminum Cell Ramming Process’ can be built
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Engineering design and analysis of pipe ramming installations
No full textThe trenchless technology known as pipe ramming for construction of culverts and buried pipes under roadways or other infrastructure has gained significant popularity due to its cost-effectiveness and ability to alleviate surface disruptions associated with open-cut trenching. Although the experience with pipe ramming is increasing, there has been remarkably little technical guidance available for engineers to appropriately specify aspects of a pipeline or culvert installation, including the planning of feasible layouts, rates of penetration, pipe diameters, and hammers. This research provides a comprehensive engineering framework for evaluation of culvert installations at the planning phase to address the gaps in knowledge associated with pipe ramming.
Presently there are no existing and proven techniques for prediction of settlement, vibration, driving stresses, soil resistance to ramming, and drivability for pipe ramming installations. This study has adopted existing drivability, soil resistance, settlement, and vibration prediction models from pipe jacking, microtunneling, and pile driving models and examined their applicability in pipe ramming installations, resulting in new and technology-specific design guidance. The development of this comprehensive engineering guidance is based on engineering calculations empirically tuned using a database of actual performance measurements. Field observations of five production installations and a full-scale experiment were conducted to form the performance database employed to understand the mechanics associated with pipe ramming installations, ranging from vertical ground movements, ground vibrations, and installation performance.
Settlement prediction was evaluated using the inverted normal probability distribution based models, and these methods over-estimated the observed settlements close to the center of the pipes and under-estimated settlements at radial distances away from the pipe. A pipe-ramming-specific hyperbolic model was developed for better prediction of the vertical settlement induced by pipe ramming in granular soils. Attenuation of observed pipe ramming-induced vibrations was modeled using a simple semi-empirical approach, and the calibrated model resulted in reasonable predictions of the ground vibrations for granular soils. The static soil resistance to ramming was evaluated using the traditional quasi-static pipe jacking models and the models resulted in inaccurate predictions for instrumented pipe ramming installations. Therefore pipe ramming-specific static soil resistance models were developed for both the face and casing resistance in granular soils. Principles of stress wave theory routinely applied in the drivability analyses for pile foundations were adopted for the evaluation of the dynamic response pipes during ramming. Reliable estimates of the static soil resistance and dynamic soil parameters were obtained through signal matching processes. Data-informed drivability analysis were performed to simulate the magnitude of driving stresses and develop drivability curves which relate the penetration resistance of a given pipe and hammer to the range of static soil resistances. The study culminates in the first comprehensive framework and recommendations for the installation of pipes by ramming, and should help owners, consultants, and contractors to appropriately plan pipe ramming installations
High temperature innovative zirconia-alumina ramming mass
No full textZirconia and high alumina ramming masses stand out as efficacious variants within the domain of unshaped refractories. In the interface between these materials, the utilization of transitional zirconia-alumina ramming mass is recommended. This study delves into the impact of alumina additive on the fundamental properties of ramming mass samples based on calcium oxide-stabilized zirconia, employing a phosphate bond. The investigation encompasses both the characterization of these samples, ranging from cold to heat-treated states across temperatures spanning 200–2100 °C, and an analysis of phase evolution throughout these conditions. The alterations in ZrO2 phases during thermal processing in the presence of Al2O3 and P2O5, along with the ramifications of these transformations on the properties of the ramming mass, are elucidated. Notably, the most comprehensive interaction between P2O5 and cubic ZrO2 materializes within the temperature interval of 1200–1400 °C, resulting in a marked destabilization of the cubic ZrO2 phase accompanied by a marginal reduction in sample strength that remains acceptable. The process of cubic ZrO2 phase destabilization reaches completion at 1700 °C. Elevating the heat treatment temperature of samples from 1700 to 2000 °C engenders the disintegration of aluminium, calcium, and zirconium phosphates, consequently leading to the re-stabilization of ZrO2. This, in turn, fosters densification and fortification of the sample structure. Designed for constituting the functional layer of linings at the interface of combustion and reaction zones within carbon black production reactors, the zirconia-alumina ramming mass with a phosphate bond showcases noteworthy potential. Experimental validation of this developed ramming mass at a carbon black plant has yielded favourable outcomes
Global ice ridge ramming loads based on full scale data and specific energy approach
No full textThis thesis analyses the loads that occurred during an ice ridge ramming experiment with the icebreaker Oden. Sea ice ridges are formed due to breaking and deformation of the ice cover. Wind, current, thermal expansion and Coriolis forces induce compression and shear forces onto level ice which can break the ice into rubble. The blocks of ice rubble are pushed together, forming a wall of broken ice in hydrostatic equilibrium. This wall of broken ice forced up by pressure is defined as an ice ridge. In general ice ridges are long, nonsymmetrical, curvilinear features with a wide variability of sizes and shapes. In Arctic regions, sea ice ridges are often used to calculate the design load in the absence of icebergs. Ice ridges also play a major role in icebreaker efficiency, since an icebreaker might need several ‘rams’ to break through an ice ridge. Ice ridge actions on icebreakers are not completely understood. Complex ice behavior under rapidly applied stress, and the complex geometries of the bodies in contact makes it a challenging research topic. The dynamic behavior of the vessel during the ramming can be used to make an estimate of the ice loads that occurred. This thesis analyses the ice load that occurred during a ridge ramming experiment that was performed with icebreaker Oden during the ODEN AT research cruise project in 2013. To advance our understanding in the global ice ridge ramming loads, twomodels were developed: 1) a simulationmodel using the Specific Energy Absorption (SEA) of mechanical crushing of ice to calculate the global ice loads, 2) a load identification model using full-scale data to determine the global ice loads. The simulation model was developed to enhance the understanding of relevant physical phenomena and parameters. During this process, specific energy principles of crushing of ice were identified as a promising although relatively unknown method for impact dynamics into ice. The Specific Energy Absorption (SEA) of mechanical crushing of ice is defined as the energy per unit mass of crushed ice, necessary to turn solid ice into crushed (pulverized) material. Besides the SEA value, the penetration velocity, density of ice, and volume of crushed ice, are required to calculate the ice load. A contact model was developed to determine the load location and direction on the hull. The icebreaker Oden is represented by a nonlinear mass-damper-spring system. Maneuvering theory is applied, which means that the hydrodynamic variables are estimated at one frequency of oscillation. In the simulation model, a known thrust force is applied on the vessel, making it move forward in open water, and then penetrate the ice ridge. The simulation model calculates the ice loads and vessel’s motions (i.e. accelerations, velocity, and displacement). The load identification model combines the Kalman filter and a joint input-state estimate algorithm to estimate the state- and excitation vector from acceleration, velocity and displacement data in 3DOF (i.e. surge, heave, pitch). The joint input-state estimate algorithm combines measured data with an estimate of the state of the system in a way that minimizes the error. The full-scale data analyzed in this thesis includes a profile of amulti-year ice ridge, vessel characteristics, acceleration data from a motion reference unit (MRU), GPS data, and propulsion data. From the results of the load identification model, we conclude that the current combination of model and data does not provide sufficient information to estimate the global ridge ramming loads with high reliability. The main reasons for this are the absence of additional MRU(s), the low sample frequency of the MRU, the data uncertainty, and the simplified hydromechanics. However, the suggested approach to calculate the global ice loads is reliable as long as the data is valid. This is verified by recalculating the ice loads from the data (i.e. motions), generated by the simulation model. Results indicate that the specific energy approach can be used to simulate an impact of a vessel into an ice ridge, under assumption that the ice fails purely due to crushing. This assumption is only valid during the beginning of the impact, as other failure modes often start to dominate as the penetration of the vessel into the ridge increases.Mechanical, Maritime and Materials EngineeringOffshore and Dredging Engineerin
A gépjárművel végrehajtott, ramming típusú terrortámadásokról és a védekezés lehetőségeiről
No full textRecently we have witnessed several attacks in Europe, in which terrorists used vehicles as their weapons. We can expect that such attacks utilizing vehicles, called ramming attacks, will proliferate because they are simple, cheap and hard to uncover. Today these means are used not only by radical Islamist terrorists, but also by other radicals and lone psychotics, as well. Ramming attacks are primarily effective when targeting mass events, therefore protection against these should also focus on protecting the people participating in such events and on developing the police and medical reaction capabilities. As parliamentary elections are coming up in Hungary, the number of mass events is also going to increase, therefore it is necessary to gain an analytical picture of ramming attacks throughout Europe to be able to guarantee safety and security in Hungary, as well.A közelmúltban Európában több olyan merénylet is történt, amelyekben a terroristák fő fegyverként gépjárművet használtak. Várható, hogy ez a gépjárműves elkövetési forma (az úgynevezett ramming) egyszerűsége, olcsósága és nehéz felderíthetősége miatt egyre gyakoribbá válik. A módszert mára nemcsak radikális iszlamisták, de egyéb szélsőségesek és magányos őrültek is használják. A rammingtámadások elsősorban tömegrendezvények ellen hatékonyak, így az ellenük való védekezésnek is leginkább a tömegrendezvények védelmére, illetve a gyors rendőri és egészségügyi reagáló képességek fejlesztésére kell koncentrálnia. A parlamenti választások közeledtével hazánkban is nőni fog a tömegrendezvények száma, így az ország biztonságának garantálása érdekében szükségessé vált az európai rammingtámadások elemzése
The Sassacus Ramming the Ablemarle
No full textIn the image, a scene from the Battle of Albemarle Sound is pictured. The USS Sassacus is shown ramming into the side of the CSS Albemarle. Despite this, the Albemarle evaded capture.https://scholarsjunction.msstate.edu/fvw-prints/1272/thumbnail.jp
On the mechanics of the ramming interaction between a ship and a massive ice floe:Dissertation
No full textThe mechanics of the interaction occurring when a ship rams a massive ice floe is analyzed.A calculation procedure to determine the ice load and the ensuing ship response is developed.The experimental values from full scale and model scale ramming trials are compared with the calculated values.The ice displacement occurring due to the ship bow penetrating into the ice floe is divided into two components.One component correspond to the crushing penetration into ice and the other is associated with the elastic deformation of ice.A formulation of these two components based on measurements and calculations is developed.The ship motions and ship hull vertical deformation are analyzed treating the ship hull as a Timoshenko beam.The water surrounding the ship hull is accounted for using the strip theory.In the calculation procedure the ship motions and ice displacement are combined by a kinematic condition.The procedure developed is applied to three ramming cases.The ramming of M.V.Arctic is studied both in model scale and full scale.The repeated ramming of Canmar Kigoriak on existing bow imprints is also studied. This study on the mechanics of ramming interaction does not include all aspects needed for ship design.The aim is to develop a model to determine ice load in ramming based on ice mechanics and ship particulars
Characterization and modelling of a carbon ramming mix used in high-temperature industry
No full textAbstractThis paper is devoted to the modelling of a specific ramming mix mainly used in the high-temperature industry due to its high-compacting behaviour. This material has the ability to absorb the deformation of parts submitted to high thermal loads. Triaxial and instrumented die compaction tests were carried out in order to identify the shear and hardening behaviours, respectively. Tests on the ramming mix were led for a temperature range between 20°C and 80°C. The temperature effect is particularly observed on the material response when it is compacted. The main features of the behaviour of the ramming mix can be represented by the theoretical framework of the Modified Cam-Clay model. A single variable allows to accurately reproduce the hardening behaviour depending on the temperature. Moreover, an extension of the model for the hardening behaviour at high pressures is proposed. A good agreement between the experimental data and numerical tests is reached with this model
Methodology For Directional Drilling In The Mode Of Ramming Pipe And Tunnel Linner
No full textLos avances tecnológicos del presente siglo permean todos los sectores industriales en la búsqueda de sistematizar y optimizar procesos que permitan avances rápidos con buenos resultados. El sector de la construcción, específicamente en las redes de servicios públicos avanza en el desarrollo de nuevas tecnologías que permiten la instalación de redes ya conformadas sin causar mayores impactos en el espacio. En el presente documento se mostrará la metodología de construcción sobre las redes subterráneas denominada a nivel mundial como perforación dirigida sin zanja la cual posee un sin número de variaciones constructivas dependiendo de la necesidad que se tenga a la hora de ser ejecutada en obra civil , la idea con el proceso metodológico de perforación es presentar las etapas constructivas idóneas en cuanto al modelo constructivo Pipe Ramming y Túnel Linner principales pioneros de perforación aplicados desde principios de los noventa y cuya evolución ha sido adquirida para el desarrollo urbanístico de la capital debido a su versatilidad , fácil manejo y pocas complicaciones espaciales que estos métodos ofrecen y su rapidez en entrega.The technological advances of this century permeate all industries in seeking to systematize and streamline processes to enable rapid progress with good results. The construction sector, specifically in utility networks advances in the development of new technologies that allow the installation of networks already formed without causing major impacts in space. In this document the methodology of construction of underground networks known worldwide as trenchless directional drilling which has a number of design variations depending on the needs that have to be executed when civil work is shown, idea methodological drilling process is to present the best construction stages in terms of building model Pipe Ramming and Tunnel Linner leading pioneers drilling applied since the early nineties and whose evolution has been acquired for the urban development of the capital due to their versatility , easy handling and little space complications that these methods offer and delivery speed
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