The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform
J.l. Yang - One of the best experts on this subject based on the ideXlab platform.
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An elastic-plastic hardening-softening cantilever beam subjected to a force pulse at its tip: a model for pipe whip
Proceedings of the Royal Society of London. Series A: Mathematical Physical and Engineering Sciences, 1998Co-Authors: Stephen R Reid, J.l. YangAbstract:A theoretical model is proposed to simulate the large deflection dynamic behaviour of an elastic–plastic, hardening–softening cantilever beam with an attached end mass subjected to a suddenly applied force pulse at its free end. The model is a development of a previous one by the present authors which was based on a small deflection formulation. Numerical examples are given to illustrate the effects of the softening parameter, α , the ratio of the end mass to the mass of the beam and the intensity of the force pulse on the dynamic reponse of a beam. The changes in shape of the beams, the growth of the softening region and the possible onset of local collapse are examined. The model, though applicable generally to beams with elastic–plastic hardening–softening characteristics, was developed primarily to describe the phenomenon of pipe whip, the large deflection behaviour of a High–Pressure Piping system following a sudden rupture of the pipe. During the motion and deformation of a whipping pipe, softening can occur in the local bending characteristic and this in turn can lead to severe localization of the deformation, i.e. the formation of a ‘kink’. Following initial elastic behaviour, the local bending behaviour of the pipe involves sequential hardening and softening phases as the pipe deforms plastically. This results from the interaction between the material properties of the pipe and the ovalization of its cross–sections as it undergoes large plastic deformations. It has been demonstrated recently that the model can accurately predict the transient deformation of the centre lines of freely whipping pipes (Reid et al . 1996). The practical issues associated with applying the theory to tubular beams (pipes) and the mesh sensitivity of the numerical solution of the governing equations are discussed herein. However, the main aim of the paper is to add to the range of beam models available for the solution of dynamic structural plasticity problems.
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Dynamic elastic-plastic behaviour of whipping pipes: experiments and theoretical model
International Journal of Impact Engineering, 1996Co-Authors: Stephen R Reid, J.l. Yang, Gabriel G. CorbettAbstract:This paper is concerned with the problem of pipe whip, the dynamic response of a High Pressure Piping system subjected to an end force as the result of a pipe break which releases a jet of fluid from the broken section. Both experimental and theoretical results are presented concerning the dynamic elastic-plastic behaviour of cantilever pipes subjected to a transverse force pulse at the free end. Comparisons between experimental data and theoretical predictions are made for mild-steel pipes with outer diameter-to-thickness ratios of 19.5, 28 and 32. It is demonstrated that, for these geometries, the whipping pipes display three characteristically different responses, viz. elastic, plastic hardening behaviour for thick pipes, elastic, plastic hardening-softening behaviour for moderately thick pipes and elastic, plastic hardening-softening-collapse behaviour for thinner pipes. The experimental data taken from a series of High-speed films are compared with the predictions of the instantaneous shapes of the whipping pipes derived from both a rigid, perfectly-plastic, large deflection, dynamic beam model and a more comprehensive model which incorporates the effects of elasticity and plastic hardening and softening, the details of which are presented in the paper.
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Hardening-softening behaviour of circular pipes under bending and tension
International Journal of Mechanical Sciences, 1994Co-Authors: Stephen R Reid, J.l. YangAbstract:Abstract A theoretical analysis, based on plastic shell theory and utilizing extremum and variational principles combined with numerical approaches, has been conducted to investigate the quasi-static flexural behaviour of mild steel circular pipes. Attention is focused on the hardening-softening relations between the bending moment and the curvature of pipes which, according to observations in pipe-whip experiments, governs the deformation process and can lead to localization. As the study is concerned with free pipe-whip behaviour of the High Pressure Piping system, in the theoretical analysis the circular pipe is assumed to be subjected to a bending moment as well as a relatively small tension force in the axial direction. In addition to numerical examples for various cases, a quasi-static four-point bending test was carried out to verify the hardening-softening moment vs curvature relation of pipes predicted by the present theory in the case of pure bending. A simpler, approximate procedure which predicts the moment-curvature relationship with reasonable accuracy is also described.
Stephen R Reid - One of the best experts on this subject based on the ideXlab platform.
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An elastic-plastic hardening-softening cantilever beam subjected to a force pulse at its tip: a model for pipe whip
Proceedings of the Royal Society of London. Series A: Mathematical Physical and Engineering Sciences, 1998Co-Authors: Stephen R Reid, J.l. YangAbstract:A theoretical model is proposed to simulate the large deflection dynamic behaviour of an elastic–plastic, hardening–softening cantilever beam with an attached end mass subjected to a suddenly applied force pulse at its free end. The model is a development of a previous one by the present authors which was based on a small deflection formulation. Numerical examples are given to illustrate the effects of the softening parameter, α , the ratio of the end mass to the mass of the beam and the intensity of the force pulse on the dynamic reponse of a beam. The changes in shape of the beams, the growth of the softening region and the possible onset of local collapse are examined. The model, though applicable generally to beams with elastic–plastic hardening–softening characteristics, was developed primarily to describe the phenomenon of pipe whip, the large deflection behaviour of a High–Pressure Piping system following a sudden rupture of the pipe. During the motion and deformation of a whipping pipe, softening can occur in the local bending characteristic and this in turn can lead to severe localization of the deformation, i.e. the formation of a ‘kink’. Following initial elastic behaviour, the local bending behaviour of the pipe involves sequential hardening and softening phases as the pipe deforms plastically. This results from the interaction between the material properties of the pipe and the ovalization of its cross–sections as it undergoes large plastic deformations. It has been demonstrated recently that the model can accurately predict the transient deformation of the centre lines of freely whipping pipes (Reid et al . 1996). The practical issues associated with applying the theory to tubular beams (pipes) and the mesh sensitivity of the numerical solution of the governing equations are discussed herein. However, the main aim of the paper is to add to the range of beam models available for the solution of dynamic structural plasticity problems.
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Dynamic elastic-plastic behaviour of whipping pipes: experiments and theoretical model
International Journal of Impact Engineering, 1996Co-Authors: Stephen R Reid, J.l. Yang, Gabriel G. CorbettAbstract:This paper is concerned with the problem of pipe whip, the dynamic response of a High Pressure Piping system subjected to an end force as the result of a pipe break which releases a jet of fluid from the broken section. Both experimental and theoretical results are presented concerning the dynamic elastic-plastic behaviour of cantilever pipes subjected to a transverse force pulse at the free end. Comparisons between experimental data and theoretical predictions are made for mild-steel pipes with outer diameter-to-thickness ratios of 19.5, 28 and 32. It is demonstrated that, for these geometries, the whipping pipes display three characteristically different responses, viz. elastic, plastic hardening behaviour for thick pipes, elastic, plastic hardening-softening behaviour for moderately thick pipes and elastic, plastic hardening-softening-collapse behaviour for thinner pipes. The experimental data taken from a series of High-speed films are compared with the predictions of the instantaneous shapes of the whipping pipes derived from both a rigid, perfectly-plastic, large deflection, dynamic beam model and a more comprehensive model which incorporates the effects of elasticity and plastic hardening and softening, the details of which are presented in the paper.
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Hardening-softening behaviour of circular pipes under bending and tension
International Journal of Mechanical Sciences, 1994Co-Authors: Stephen R Reid, J.l. YangAbstract:Abstract A theoretical analysis, based on plastic shell theory and utilizing extremum and variational principles combined with numerical approaches, has been conducted to investigate the quasi-static flexural behaviour of mild steel circular pipes. Attention is focused on the hardening-softening relations between the bending moment and the curvature of pipes which, according to observations in pipe-whip experiments, governs the deformation process and can lead to localization. As the study is concerned with free pipe-whip behaviour of the High Pressure Piping system, in the theoretical analysis the circular pipe is assumed to be subjected to a bending moment as well as a relatively small tension force in the axial direction. In addition to numerical examples for various cases, a quasi-static four-point bending test was carried out to verify the hardening-softening moment vs curvature relation of pipes predicted by the present theory in the case of pure bending. A simpler, approximate procedure which predicts the moment-curvature relationship with reasonable accuracy is also described.
Jan Olsson - One of the best experts on this subject based on the ideXlab platform.
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Stainless steels for SWRO plants High-Pressure Piping, properties and experience
2003Co-Authors: Jan Olsson, Kenan CosicAbstract:This issue of Acom will be devoted to desalination. We have not covered that subject since 1995 despite its large interest not only for the stainless steel industry, but also for people in general. We can almost daily read in the newspapers about pollution of fresh water sources such as rivers and lakes, lowered ground water tables, wells that are running dry or becoming polluted by penetrating seawater, extended periods between the rain required for crops to grow etc. The list of water problems seems sometimes endless. One way to solve at least some of the problems is to remove the salt from seawater, i.e. by using desalination. There was recently a large desalination conference in Bahamas, “IDA World Congress on Desalination and Water Reuse”, where several interesting papers were presented. In this issue of Acom you will find two of them describing the use of special stainless steels for two different desalination processes. The first paper, “Stainless steels for SWRO plant High-Pressure Piping, properties and experience” (p.2) describes a comprehensive survey of stainless steel grades used for seawater reverse osmosis plants and the experience reported for grades ranging from 316L up to the Highly alloyed 254 SMO® and SAF 2507®. There is also an addendum to this paper reporting some recent experience about corrosion in 316L and 904L. This information was received too late to be included in the paper but it really emphasises the conclusions drawn in the paper. The second paper, “MSF chambers of solid duplex stainless steel” (p.11) describes how the cost of evaporator vessels for an MSF (Multi Stage Flash) plant in Libya was reduced by the use of the stronger 2205 instead of conventional 316L. On top of that they got a far more corrosion resistant plant. In another paper (not included in this issue of Acom) at this conference an Italian engineering company showed how they could reduce the cost of the evaporators by more than 1.2 million US-dollars when designing in 2205 instead of 316L clad steel, i.e. they proposed a similar concept as in the paper I hope you will read in a few minutes.
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Stainless steel for High Pressure Piping in SWRO plants. Are there any options
Desalination, 1994Co-Authors: Johan Nordström, Jan OlssonAbstract:Abstract Service experiences from 27 sea water reverse osmosis (SWRO) plants confirm that there is an evident risk of corrosion if wrong steel grade is used for the High Pressure Piping. Neither 316L nor 317L possesses sufficient corrosion resistance. Not even Highly alloyed grades like 2205 and 904L show reliable service performance. However, no corrosion has been reported for 254 SMO, which has been used in 16 full strength SWRO plants and several plants using High salinity brackish water.
Tahseen A. Saki - One of the best experts on this subject based on the ideXlab platform.
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Improving the design stresses of High density polyethylene pipes and vessels used in reverse osmosis desalination plants
Journal of Saudi Chemical Society, 2010Co-Authors: Abdulwahid Al-hajjaj, Tahseen A. SakiAbstract:Abstract Nanocomposite materials have been used on a wide scale in industrial and structural applications. The present work aims at studying the mechanical properties of High density polyethylene (HDPE) grade TR-401 hexene copolymer reinforced by montmorillonite nanoparticles (MMT), used to fabricate pipes and membranes vessels for reverse osmosis desalination plants. Different volume fractions and particle sizes of the MMT clay were used to investigate the effect of this filler on the mechanical properties of the produced composite. Mechanical properties tests were carried out and good improvements of the composite properties were obtained compared to the parent polymer. The test results showed a significant enhancement of the mechanical properties at low filler proportions. Pipe fabricated from these composites had many outstanding and desirable features. For example, by adding 4.75% MMT to the HDPE produced quality pipes and fittings with the Highest design stress basis of any polyethylene. A significant increase in the modulus of elasticity observed, together with an unusual increase in the design stress, approved the HDPE/MMT composite for High Pressure Piping and membrane vessels used in reverse osmosis desalination plants.
Rm Kain - One of the best experts on this subject based on the ideXlab platform.
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Economic material selection for reverse osmosis desalination plants
Desalination, 1991Co-Authors: J.w. Oldfield, Rm KainAbstract:Abstract For Reverse Osmosis plants, the large variation in water composition and the large number of metallic materials on the market, make selection of the optimum material on both technical and economic grounds difficult, even for the corrosion specialist. This paper gives a general review of stainless steel and describes the results of an extensive programme of work commissioned by the Nickel Development Institute to develop a ‘Corrosion Atlas’ of stainless steels to solve this problem. Data is presented on the performance of a range of austenitic materials, allowing optimum selection for High Pressure Piping, pumps, filter bodies etc in Reverse Osmosis plants handling sea water, brackish waters and fresh waters.