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Dissertations / Theses on the topic 'Welding of plastic pipes'

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Published: 4 June 2021

Last updated: 2 February 2022

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1

No, Donghun. "A study of the combined socket and butt welding of plastic pipes using through transmission infrared welding." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1104437266.

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2

Shillitoe, Stephen. "A study of the butt fusion welding of thermoplastic pipes." Thesis, University of Bradford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235570.

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3

No, Dong Hun. "A study of the combined socket and butt welding of plastic pipes using through transmission infrared welding." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1104437266.

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Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xxi, 221 p.; also includes graphics (some col.) Includes bibliographical references (p. 218-221).

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4

Cosgrove, Brian George. "The toughness characteristics of butt fusion and electrofusion joints in polyethylene water pipe." Thesis, Manchester Metropolitan University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239469.

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5

Rashid, Haroon. "Butt fusion welding of polyethylene pipes." Thesis, Brunel University, 1997. http://bura.brunel.ac.uk/handle/2438/6623.

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The butt fusion process is extensively used in the joining of polyethylene (PE) pipes by the water and gas industries. This welding process although deceptively simple, is rather poorly understood, with much of the initial developments being of a rather empirical nature. The Water Research centre (WRc) have funded the present research in an attempt to optimise the welding of high pressure pipeline (PE100) systems. The main aims of this research were to investigate the effect of different welding conditions on the physical and mechanical properties of the joints produced and to investigate these effects on the micro- and macro-structures of the joints produced. A series of welds were made using Eltex Tub 124 and Rigidex 002-50 pipes of 180mm diameter. The fusion pressure and heatsoak times were varied. A milling machine witha twin cutter arrangement was used to obtain the test specimens from around the circumference of the pipes. Differential scanning calorimetry was used to study the effect of sample preparation methodology on the thermo-oxidative stability. Polarised light microscopy and image analysis were used to study the macro- and micro-structural developments in the weld joint. Joint strength was evaluated via standard and non-standard tensile test methods. Milling the samples to produce the test specimens was found to decrease significantly the thermo-oxidative resistance of the polymer. Reasons for this behaviour have been proposed. In order to achieve high quality thin films from microtomy, custom-made blades were used. This programme also developed the optimum polishing method for the microtomed blades. The macro-structure of the bead: its shape and dimensions were found to be a function of temperature and pressure. Correlation was found between the bead geometry and the position around the circumference of the pipe. The macrostructures within the weld zone also showed this dependence on the position along the circumference of the pipe. An examination of the microstructures of each weld had shown the presence of five different zones. The feasibility of using microtomed thin sections in a tensile test was demonstrated. The test method provides a means to study failure initiation and propagation in the tensile test specimen. Initial deformation was found to occur in the centre of the melt-affected zone (MAZ) and the final failure occurs at the junction of the weld bead and the bulk polymer. Tests on films without the weld bead showed that maximum deformation occurred at the centre of the sample within the MAZ. The presence of the bead and the asymmetry in the test specimens caused by the welding process were found to have a significant influence on the failure mode and the failure strain. The strain rate was also found to play a significant role in both beaded and debeaded samples. The failure was initiated from the pseudo notches in the beaded samples. In the debeaded sample the failure was within the MAZ.

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6

Gao, Yan. "Leak detection in plastic water pipes." Thesis, University of Southampton, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423122.

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7

Yan, Pei. "High frequency induction welding & post-welding heat treatment of steel pipes." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609702.

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8

Sævik, Svein. "On stresses and fatigue in flexible pipes." Norway : Dept. of Marine Structures, the University of Trondheim, 1992. http://catalog.hathitrust.org/api/volumes/oclc/27348152.html.

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9

Chan, Che Wan. "The ultrasonic nondestructive evaluation of welds in plastic pipes." Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/7208.

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10

Greenshields, Christopher John. "Fast brittle fracture of water/air pressurised plastic pipes." Thesis, Imperial College London, 1995. http://hdl.handle.net/10044/1/8690.

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11

Davies, Edward. "Development of a hand-held multicell inverter-based ultrasonic plastic welder." Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/1093.

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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009
This thesis presents the design and development of a multicell inverter for ultrasonic plastic welding applications and other ultrasonic applications. An overview of the main multilevel topologies is given, but this research focuses on the multicelll inverter, because of its capacitor voltage balancing properties. Loading effects of various plastic materials to an ultrasonic plastic welding tool are provided in this thesis. A simple method to create an approximate electrical equivalent circuit of the ultrasonic welding tool, using an impedance analyser, loaded with different plastics is discussed and illustrated. Experimental results of the four-level multicell inverter driving a resistive load and an ultrasonic transducer tool are presented in this thesis. These results provide proof that the multicell inverter topology is capable of driving a non-linear load. The inverter was tested with the ultrasonic load as an ultrasonic plastic welder and an ultrasonic drill. The welding joints on the plastic samples are also evaluated in order to evaluate whether or not this solution is suitable for plastic welding. The ultrasonic drilling results are also shown in this thesis. It is further illustrated that the ultrasonic tool and power supply combination may be used in other ultrasonic applications.

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12

Ibrahim, M. K. "Algorithms for spectrum estimation and detection of buried plastic pipes." Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382869.

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13

Morgan, Robert Edward. "Ductile-brittle transitions in pipe grade polyethylene." Thesis, Imperial College London, 1994. http://hdl.handle.net/10044/1/7399.

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14

Schehl, Donald J. "Monitoring of thermoplastic pipes under deep cover." Ohio : Ohio University, 2000. http://www.ohiolink.edu/etd/view.cgi?ohiou1172865071.

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15

Fernando, Mihindukulasooriya E. R. "Field performance of corrugated plastic pipes under simulated high soil cover." Ohio : Ohio University, 1992. http://www.ohiolink.edu/etd/view.cgi?ohiou1172266770.

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16

Kalra, Rajesh. "Structural performance of jointed plastic pipes under a simulated high landfill." Ohio : Ohio University, 1994. http://www.ohiolink.edu/etd/view.cgi?ohiou1177532510.

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17

Hu, Fang Zong. "Fatigue of glass reinforced plastic pipes and joints for offshore applications." Thesis, University of Newcastle Upon Tyne, 1997. http://hdl.handle.net/10443/678.

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In this thesis the static and fatigue characteristics of glass filament wound plastic pipes and joints are examined by experiments and numerical analysis. A hydraulic fatigue test rig, capable of exerting static or cyclic pressures of up to 70 MPa, was designed and built to enable pressure tests to be carried out on glass reinforced epoxy and glass reinforced vinyl ester composite pipes incorporating various joints. Static weepage and burst tests were performed on tubular specimens with and without rubber liners to determine their weepage and burst strengths under internal hydraulic pressure and to investigate the influence of the joints. Fatigue weepage tests were performed to determine the fatigue life and failure modes of glass fibre/epoxy and glass fibre/vinyl ester pipes and joints. For each material system, three types of specimen were tested. These were plain pipes, pipes with coupler-bonded joints (or laminate joints in the case of vinyl ester resin based pipes) and pipes with spigot/socket bonded joints. All specimens were commercial products with nominal diameters of two inches (50 mm). A family of curves showing pressure versus life was obtained. It was observed that weepage mostly occurred close to the pipe joints when pipes were subjected to internal pressure. Optical microscopy was used to investigate the damage initiation and propagation mechanisms in the specimens after testing. Finally, two-dimensional and three-dimensional finite element analyses were carried out to calculate the stress and strain distributions, to predict the strength, to interpret the experimental results and to examine the failure modes of the specimens. Ply-by-ply stress analysis and the Tsai-Wu failure criterion were employed for the strength prediction.

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18

Papastefanou, Anastasia. "An experimental investigation of leak noise from water filled plastic pipes." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/190853/.

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19

Kroll, Martin, Peter Birnbaum, Josephine Zeisig, Verena Kraeusel, and Martin Franz-Xaver Wagner. "Manufacturing of 42SiCr-Pipes for Quenching and Partitioning by Longitudinal HFI-Welding." MDPI AG, 2019. https://monarch.qucosa.de/id/qucosa%3A34778.

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In the pipe manufacturing and pipe processing industry, the demand for cost-effective pipes with high strength and good ductility is increasing. In the present study, the inductive longitudinal welding process was combined with a Quenching and Partitioning (Q&P) treatment to manufacture pipes with enhanced mechanical properties. The aim of the Q&P process is to establish a martensitic structure with increased retained austenite content. This allows for the beneficial use of both phases: the strength of martensite as well as the ductility of retained austenite. A 42SiCr steel, developed for Q&P processes, was joined at the longitudinal seam by a high-frequency induction (HFI) welding process and was subsequently heat-treated. The applied heat treatments included normalizing, austenitizing, quenching, and two Q&P strategies (Q&P-A/Q&P-B) with distinct quenching (Tq = 200/150 °C) and partitioning temperatures (Tp = 300/250 °C). Investigations of the microstructures revealed that Q&P tubes exhibit increased amounts of retained austenite in the martensitic matrix. Differences between the weld junction and the base material occurred, especially regarding the morphology of the martensite; the martensite found in the weld junction is finer and corresponds more to the lath-type morphology, compared to the base material in the circumference. In all zones of the welded tube circumference, retained austenite has been found in similar distributions. The mechanical testing of the individual tubes demonstrated that the Q&P treatments offer increased strength compared to all other states and significantly improved ductility compared to the quenched condition. Therefore, the approach of Q&P treatment of HFI-welded tubes represents a route for the mass production of high-strength tubular products with improved ductility.

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20

Gondle, Raj Kumar. "Finite element analysis of long-term performance of buried high density polyethylene pipes." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4935.

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Thesis (M.S.)--West Virginia University, 2006.
Title from document title page. Document formatted into pages; contains x, 122 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 116-122).

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21

Lobato, de Almeida Fabrício César. "Improved acoustic methods for leak detection in buried plastic water distribution pipes." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/355964/.

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This thesis is concerned with a theoretical and experimental investigation into the enhancement of acoustic methods used to detect leaks in buried plastic water distribution pipes. Although acoustic methods have been successfully used for leak detection in metallic pipes, they are less effective in plastic pipes due, for example, to the high attenuation of leak noise signals. Two specific problems investigated in this thesis. They are the uncertainty involved in the calculation of the time delay in arrival times between two leak signals, and the variation of speed at which the leak noise propagates in the pipe. This is done in both the time and frequency domains. A new way to estimate the wave speed from measurements made in the presence of a leak is also proposed, together with a way of estimating the attenuation of leak noise as it propagates in the pipe. A bespoke test-rig was designed and built specifically for this project by South Staffs Water plc, so that leaks could be simulated and investigated in controlled conditions. Following the characterisation of the test rig, two specific correlators were investigated, one using the basic cross-correlation (BCC) function and other using the phase transform (PHAT). It is shown that the BCC is more suitable for leak detection, when the pipe exhibits resonance behaviour. It is further shown that the bandwidth over which the analysis is conducted is crucial to locate the leak accurately. To determine this bandwidth a procedure is developed to determine automatically low and high frequency cut-off frequencies of a band-pass filter. This method uses both the coherence and the modulus of the cross-spectral density (CSD) function between two leak noise signals. A new technique is also proposed to calculate the time delay estimate using both the modulus and phase of the CSD function, and this is validated using a wide range of data from the bespoke test-rig and also from a Canadian test-rig. Moreover, an expression for the variance of the time delay estimate is determined based on frequency domain data, and this is shown to give the same result as that previously determined in the time domain. Using the variance and statistical analysis a range of values that the time delay estimate can assume is calculated. This range of values is related to the 95% confidence interval of the time delay estimate calculated using the weighted least squares fit. The confidence interval can also be applied to the wave-speed estimate. The time delay and wavespeed estimates can be combined to determine a region where a leak is likely to be located in a pipe rather than giving an exact position as provided by commercial correlators. Measured data is used to validate the approach using the bespoke test-rig.

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22

da, Costa Pépe Nuno Vasco. "Advances in gas metal arc welding and application to corrosion resistant alloy pipes." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4501.

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According to recent estimations, the construction of pipelines will continue to increase during the next thirty years, in particular as a result of oil and gas discoveries in remote locations. Significant advances in welding technology during the last ten years have potential to provide improvements in productivity, quality and structural integrity of pipe girth welds. In this thesis, several new processes Lincoln STT, Lincoln RapidArc, Fronius CMT, Fronius CMT-P and Kemppi FastROOT have been compared the first time to the GMAW-P to understand how these new waveforms operate for pipe welding. The process setting parameters have been analysed to understand their effect on metal transfer and arc stability control, and on bead shape characteristics. Although all waveforms present similar burn-off ratios, individual waveforms differ considerably, and especially the arc voltage waveform. This leads to considerable differences in the mechanism of metal transfer and the stability of the processes under similar experimental conditions. Understanding of these new waveforms in terms of the effect of setting parameters in the mechanism of metal transfer, process stability and melting phenomena provides a basis for assessing the potential of these processes for a range of applications, and in particular application to CRA pipe root welding Since the arc energy is the overall energy delivered from the power source at the contact tip of the torch, and part of that energy is not absorbed by the workpiece, research was performed to measure the process efficiency associated with some of these waveforms and process setting conditions. The study led to a better understanding of the potential errors in calculating process efficiency. The results obtained show that all the short-circuiting waveforms analysed (i.e. CMT, STT and FastRoot) had a similar process efficiency of 90±3%, while pulse spray waveforms (GMAW-P, CMT-P and RapidArc) are characterized by lower process efficiency, approximately 78±3%. The application of these waveforms to the welding a narrow groove pipe with a “J” groove design was investigated. These analyses were focused on the variation of bead shape characteristics and welding quality performance based on the analysis of the conditions that result in lack of penetration and top bead defects, such as lack of side wall fusion or undercutting. It was observed that RapidArc and CMT-P are able to satisfy the quality requirements, i.e. full penetration and absence of defects for the specific conditions described in this thesis. High welding speeds (up to 1m/min) were achieved with these processes, four times the typical speed 0.25m/min. Finally, the shielding gas plays an important role in terms of quality and weld bead performance. This led to an optimization of the shielding gas composition used, based on mixtures of carbon dioxide, argon and helium. Statistical modelling was undertaken to optimize the shielding gas mixtures using RapidArc and CMT-P waveforms. In parallel, a new purging shielding gas device was designed to achieve a weld root free of oxidation.

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23

Wheel, Marcus A. "High speed double torsion testing of pipe grade polyethylenes." Thesis, Imperial College London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318493.

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24

Simmons, Andrew Ray. "Use of flowable fill as a backfill material around buried pipes." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2477.

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Thesis (M.S.)--West Virginia University, 2002.
Title from document title page. Document formatted into pages; contains viii, 152 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 87-91).

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25

Ainsworth, Kim. "Low velocity transverse impact of filament wound E-glass/epoxy resin pipes." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293699.

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26

Strand, Seth R. "Effects of Friction Stir Welding on Polymer Microstructure." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd338.pdf.

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27

Chevallier, Elise Camille. "Assessment of welding induced plastic strain using the thermoelastic stress analysis technique." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/420750/.

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The work presented in the thesis is dedicated to the development and validation of a new technique to assess plastic strain based on thermoelastic stress analysis (TSA). Welding induced plasticity (WIP) and welding residual stresses can negatively affect the structural integrity of welded structures as they can exacerbate creep and stress corrosion cracking and limit the structure’s resistance to failure. Moreover, WIP has been shown to negatively affect weld integrity, since the associated accumulation of defects (dislocations) in the material will accelerate the nucleation of macro-scale defects that lead to component failure. There has been considerable amount of work published on determining the magnitude and distribution of the residual stresses both experimentally and by using numerical techniques. WIP can be predicted using finite element analysis (FEA), however, there is currently no standardised experimental method to characterise plastic strain and hence, model predictions are not readily validated with confidence. Recently, two techniques, based on electron backscatter diffraction and indentation respectively, were developed to assess WIP. However, both techniques are destructive and would not be applicable on in-situ components. TSA is a non-contact stress analysis method which is quick to apply and fully portable. TSA is based on the measurement of a small temperature change that occurs as a result of a change in the stress. The small temperature change is measured using an infrared detector. A method for plastic strain assessment (PSA) using TSA has been proposed based on the change in the thermoelastic response due to the plastic strain a material has experienced during a process, e.g. deformation or welding. TSA has the potential to be the first nondestructive, non-contact plastic strain assessment technique, termed as TSA-PSA. The aim of the PhD is to investigate the potential of using the TSA-PSA approach for assessing WIP in austenitic (AISI 316L) and ferritic (SA508 Gr.3 Cl.1) steels. The influence of welding induced microstructural changes on the thermoelastic response is investigated to establish any changes in the thermoelastic response relating to plastic straining only. The study focuses on two typical nuclear grade steels; ferritic SA508 Gr.3 Cl.1 and austenitic stainless steel AISI 316L. The effect of plastic strain on the thermoelastic response of both steels is investigated through the design and assessment of a calibration specimen used to determine the thermoelastic constant variation with plastic strain alongside with microstructural changes. It was found that the plastic strain has a stronger influence on the thermoelastic constant in SA508 than in AISI 316L. For uniform microstructures the influence of plastic strain on the thermoelastic response can be defined and, a larger influence of plastic strain on thermoelastic response was reported for coarse grains of austenite in AISI 316L and coarse grains of ferrite in SA508. The second part of the work concerns development finite element (FE) models of weld mock-ups to demonstrate application of TSA-PSA. The modelling enabled the plastic strain experienced during welding to be predicted and adjustments made to the design prior to the mock-up manufacture. Once satisfied that the mock-ups were suitable for TSA, they were manufactured at TWI Ltd. TSA experimental work was conducted on each mock-up and the outcome was compared with the outputs from the calibrated FE models. The capability of TSA to identify plastic strain in welded components is assessed through the use of the weld mock-ups. The thesis makes a novel contribution to the development of TSA as a portable non-destructive, non-contact technique to assess WIP in components with the investigation of the influence of microstructural changes similar to that found in welds on the technique, as well as the design, manufacture and plastic strain predictions in weldments dedicated to the technique. The results indicate a stronger influence of the plastic strain on the thermoelastic constant in coarse-grained microstructure in both grades of steel.

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28

Marcus, Miranda. "Theory Driven Engineering Model to Predict Ultrasonic Weld Strength of Plastics." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1605556381223829.

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29

Rosala, George Florin. "The process mechanics of polymer pipes welding by electro-fusion : a theoretical and experimental analysis of the electro-fusion welding process applied to polymer pipes. Process modelling using finite element and finite difference methods." Thesis, University of Bradford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.574642.

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This thesis presents a theoretical and experimental investigation into the modelling of the electro-fusion process, applied to welding polymer pipes. The theoretical background of the transient heat transfer between the fitting and pipe, including variable interface thermal resistance and involving consecutive changes of phase (melting and re-solidification) and the problem of the thermo-mechanical induced stresses in the joint, are fully discussed. Three 2D axisymmetric models of the EFW process, with different degrees of complexity, have been developed, refined and validated by comparison with experimental data: a finite element coupled model, with both temperature and displacement degrees of freedom, and two sequential heat transfer models, finite element and finite difference based. The effect of the melt movement into the fitting-pipe initial clearance is discussed and has been modelled by a 'virtual material movement' method. For the sequential models a 'gap evolution model' has been developed to describe the closure of the initial fitting-pipe gap through the process. Results from the simulations of the electro-fusion welding process performed using all three models, which give an exceptionally good insight into the temperature, displacement and stress fields within the joint, are fully discussed and validated through comparison with experimental data.

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30

Mada, Hemachandar. "Numerical modeling of buried pipes with flowable fill as a backfill material." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4262.

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Thesis (M.S.)--West Virginia University, 2005.
Title from document title page. Document formatted into pages; contains x, 157 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 128-132).

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31

Venkatesan, Arvind. "WAVE MOTION IN ELASTIC-PLASTIC SOLIDS BY SPACE-TIME CONSERVATION ELEMENT AND SOLUTION ELEMENT METHOD." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1367581029.

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32

ITOH, Y., Y. KITANE, and X. CHEN. "Compression Behaviors of Thickness-Reduced Steel Pipes Repaired with Underwater Welds." Elsevier, 2011. http://hdl.handle.net/2237/18823.

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33

Mason, Nicholas Scott. "The asset lives of plastic pipes : technical and economic factors affecting the in-service life of pressurised polymer pipes in the water industry." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/8218.

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34

Hengprathanee, Songwut. "Evaluation of the geometry effect of the profile of high density polyethylene pipes." Ohio : Ohio University, 2000. http://www.ohiolink.edu/etd/view.cgi?ohiou1172000993.

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35

Glennon, Dermot. "A study of the molecular organisation in structural PVDF." Thesis, University of Portsmouth, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310418.

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36

Lim, C. S. "Plastic limit pressures for pressure vessels with defects at openings." Thesis, Cardiff University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234339.

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37

Parise, Luís Fernando Schiano. "Fully plastic J and CTOD estimation procedure for circumferential surface cracks in biaxially loaded pipes." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-14122014-171536/.

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The main goal of this work is to develop an estimation procedure for the and CTOD driving forces for circumferential surface cracks in pipelines under combined bending and internal pressure loading. It is intended that the methodology proposed here will be applicable to a significant range of pipe and crack geometries, material yielding and strain hardening characteristics as well as loading biaxiality levels. In particular, pipelines currently employed in the offshore oil and gas production industry constitute an important class of potential application for this kind of procedure, and thus the current structural integrity concerns involving the reeling of pressurized pipelines have served as a motivating theme and bridge with real-world application throughout this research. The central theoretical framework upon which the developments presented here are based is the driving force estimation scheme known as EPRI methodology. This traditional approach for estimating and CTOD relies on splitting the driving forces into elastic and plastic components. The elastic part is calculated directly from widely available stress intensity factor solutions, while the plastic part is determined using fully plastic solutions derived from power-law descriptions of material behaviour. In the first part of this work the EPRI methodology in its more conventional form is extended to cover the cases of interest, allowing the calculation of and CTOD for circumferential surface cracks in pipelines subjected to combined internal pressure and bending loadings. This is done by carrying out detailed finite element simulations of bending of pressurized cracked pipes, the results of which then allow the direct determination of non-dimensional functions that correlate (CTOD) with applied loading, consistent with the form of the original EPRI fully plastic solutions. In the second part of the work attention is given to certain drawbacks and limitations of the procedure developed in the first part. A new, alternative procedure is then proposed which aims to overcome these problems by combining the main ideas behind the EPRI methodology with concepts from strain based design. The theoretical framework underlying this development is laid out and the analytical derivation of the new driving force estimation scheme is presented. Finally, results are given in a form similar to that employed in the first part, and the two procedures are compared. While they are shown to be conceptually equivalent, the strain based methodology is argued to be more readily applicable to some important classes of real world problems. The work concludes with comments on the effects of load biaxiality over crack driving forces and with discussions on the quality, accuracy and physical meaningfulness of the non-dimensional scaling functions obtained which correlate crack driving forces to loads or strains.
O objetivo principal deste trabalho é o desenvolvimento de um procedimento para estimação das forças motrizes e CTOD para trincas circumferenciais superficiais em dutos submetidos a carregamento combinado de flexão e pressão interna. Pretende-se que a metodologia aqui proposta seja aplicável a uma ampla faixa de geometrias de duto e trinca, características de escoamento e encruamento de material e níveis de biaxialidade de carregamento. Em particular, dutos atualmente empregados na exploração submarina de óleo e gás constituem uma classe importante de aplicações em potencial para procedimentos dessa natureza. Por essa razão, a avaliação de integridade estrutural de dutos pressurizados submetidos a enrolamento em carretel serve como tema motivador e ponto de conexão com a aplicação real ao longo deste trabalho. A base teórica fundamental sobre a qual se assentam os desenvolvimentos aqui propostos é o procedimento de estimação de forças motrizes de trinca conhecido como metodologia EPRI. Este método tradicional de cálculo de e CTOD separa as forças motrizes em componentes elástica e plástica. A component elástica é calculada diretamente a partir de soluções para o fator de intensidade de tensões, que se encontram amplamente disponíveis. A componente plástica, por sua vez, é determinada a partir de soluções totalmente plásticas derivadas de um modelo de lei de potência para o comportamento do material. Na primeira parte deste trabalho a metodologia EPRI em sua forma tradicional é estendida para abranger os casos de interesse, permitindo assim a determinação de e CTOD para trincas circumferenciais superficiais em dutos carregados por flexão e pressão interna. Para isto empregam-se simulações computacionais por elementos finitos, os resultados das quais permitem a determinação direta de fatores adimensionais que correlacionam (CTOD) com o carregamento aplicado de maneira consistente com as soluções totalmente plásticas da metodologia EPRI original. Na segunda parte do trabalho a atenção se volta para algumas deficiências e limitações da metodologia desenvolvida na primeira parte. Um procedimento novo é proposto como alternativa, tendo por objetivo superar estas dificuldades a partir da combinação dos principais conceitos da metodologia EPRI com ideias derivadas do projeto baseado em deformações. Apresentam-se a base teórica subjacente à estes conceitos e a derivação analítica do novo procedimento de estimação de forças motrizes. Finalmente, resultados semelhantes aos obtidos na primeira parte são calculados e os dois procedimentos são comparados. Embora ambos sejam conceitualmente equivalentes, argumenta-se que o procedimento baseado em deformações é mais imediata e convenientemente aplicado a algumas classes importantes de problemas práticos. O trabalho encerra com comentários acerca dos efeitos de biaxialidade de carregamento sobre as forças motrizes de trinca e com discussões sobre a acurácia, relevância, e significância física das funções adimensionais que escalam as forças motrizes com cargas ou deformações.

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Zhang, Xiangping. "Characterization of filament wound GRP pipes under lateral quasi-static and low velocity impact loads." Thesis, University of Aberdeen, 1998. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU551705.

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Glass-fibre reinforced plastic pipes are widely used to convey fluids for various purposes. They offer a number of distinct advantages over conventional metals, such as high specific strengths, high specific moduli, superior corrosion resistance and low coefficient of thermal expansion. However, their behaviour under lateral quasi-static and impact loading are still not well known. The research programme described in this thesis was designed to characterise the performance of 55° winding angle GRP pipes, subjected to lateral quasi-static and impact loading. Two approaches: experimental tests and finite element analysis, were used to investigate the behaviour of the GRP pipes. The experimental investigation was started with diametral compression of short GRP pipes to examine the structural behaviour and failure mechanisms. Subsequently, lateral indentation tests were conducted on rigid-foundation supported or simply supported specimens using two different indenter geometries: line-ended and flat-ended. Furthermore, low-velocity impact tests were performed under similar conditions as those for indentation tests in order to characterise the response of the GRP pipes and to identify the correlation between the two forms of loading. The pipes exhibited multi-mode failure mechanisms, resin cracks, delaminations and fibre breakage. It is found that delamination, which resulted in significant loss in stiffness and strength, was the most significant mode of failure for the GRP pipes. A good correlation in behaviour was identified between quasi-static indentation and its energy equivalent low-velocity impact when the global bending stiffness of the GRP specimens were high. Specimens with span S 10.5D i, where Di is the internal diameter of the pipe, are considered to have high bending stiffness, while simply supported specimens with S10.5D i have low bending stiffness. Irrespective of the support conditions and loading type, specimens with high bending stiffness followed a failure mechanism sequence: local resin failure, delamination and the fibre breakage. However, the large global bending experienced by low bending stiffness specimens resulted in a change of failure mechanism, only local damage and surface tensile cracks were observed.

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Kastner, Robert Eugene Lee. "Structural performance of plastic pipe used for landfill leachate collection." Ohio : Ohio University, 1992. http://www.ohiolink.edu/etd/view.cgi?ohiou1172687975.

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Vishwakarma, Anmol. "Development Of A Performance Analysis Framework For Water Pipeline Infrastructure Using Systems Understanding." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/87081.

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The fundamental purpose of drinking water distribution systems is to provide safe drinking water at sufficient volumes and optimal pressure with the lowest lifecycle costs from the source (treatment plants, raw water source) to the customers (residences, industries). Most of the distribution systems in the US were laid out during the development phase after World War II. As the drinking water infrastructure is aging, water utilities are battling the increasing break rates in their water distribution system and struggling to bear the associated economic costs. However, with the growth in sensory technologies and data science, water utilities are seeing economic value in collecting data and analyzing it to monitor and predict the performance of their distribution systems. Many mathematical models have been developed to guide repair and rehabilitation decisions in the past but remain largely unused because of low reliability. This is because any effort to build a decision support framework based on a model should rest its foundations on a robust knowledge base of the critical factors influencing the system, which varies from utility to utility. Mathematical models built on a strong understanding of the theory, current practices and the trends in data can prove to be more reliable. This study presents a framework to support repair and rehabilitation decisions for water utilities using water pipeline field performance data.
Master of Science

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41

Anantharaman, Satish. "RESIDUAL STRESS MEASUREMENT IN PLASTIC WELDED JOINS AND ITS APPLICATION TO THE DESIGN AND MANUFACTURE OF HYBRID ELECTRIC VEHICLE BATTERIES." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250695031.

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42

Al-Tarawneh, Bashar K. "Comparison between field and analytical results on the structural performance of deeply buried 42 & 60-inch diameter high density polyethylene pipes." Ohio : Ohio University, 2002. http://www.ohiolink.edu/etd/view.cgi?ohiou1174411226.

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43

Wu, Guiyi. "The influence of long-range residual stress on plastic collapse of pressurised pipes with and without flaws." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.681731.

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Structural integrity assessments of pressurised pipes include plastic collapse as a potential failure mode. This dissertation uses analytical and numerical models as well as experiments to explore the effect of displacement controlled loading conditions and fixed load conditions on the collapse pressure of pipes with and without flaws. Open- and closed-ended pipes are considered. The displacement controlled uniform stress and bending stress represent long-range or fit-up residual stress. Such long-range residual stress, resulting from misfit between components of an engineering structure, is associated with significant elastic follow-up and is commonly treated as primary stress which contributes to plastic collapse. However, this approach may be incorrect as residual stress can be relaxed. There is little evidence that explores the relationship between longrange residual stress and plastic collapse in a pressurised pipe. In this thesis the finite element method and experiments are developed to consider the effect of long-range residual stress on plastic collapse of pressurised pipes. Pipes in a number of states are considered: short and long pipes with no flaws, part and full circumferential flaws. The flaws consist of either a crack or a slot on the internal or external surface of the pipe. Both local and global collapse pressures are considered. It is found that global collapse of pressurised pipes containing longrange residual stress is not dependent solely on the level of initial stress but also on the length of the pipe, the flaw geometries and the collapse dominated stress. It is shown that the displacement controlled stress can act either as secondary stress or as primary stress. Finally, before considering the role of long-range residual stress in failure assessment diagrams, the level of elastic follow-up for full circumferentially flawed pipes is quantified and closed-form approximations of plastic collapse pressures are proposed to consider when a long-range residual stress is treated as either a secondary stress or a primary stress. The results from this work show that conservative assessments will be made of the collapse pressures of pipes containing flaws if a long-range residual stress is simply taken to be an equivalent form of mechanical loading.

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Masada, Teruhisa. "Structural performance of profile-wall plastic pipes under relatively shallow soil cover and subjected to large surface load." Ohio : Ohio University, 1996. http://www.ohiolink.edu/etd/view.cgi?ohiou1174611925.

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45

Kirkwood, Michael George. "Plastic loads for branch pipe junctions subjected to combined internal pressure and in-plane bending moments." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257705.

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Moran, Alan P. "Comparison between field and analytical results on the structural performance of deeply buried 30-inch diameter thermoplastic pipes." Ohio : Ohio University, 2001. http://www.ohiolink.edu/etd/view.cgi?ohiou1174052234.

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Vishal, Vaibhaw 1978. "Plastic buckling in gas transmission line-pipes, cold formed from thermo-mechanically-controlled rolling of low-allow steel plates." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40359.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.
Includes bibliographical references (leaves 157-164).
The need for energy infrastructure has led to transportation of gases over long distances. The strength-grade of pipeline steels used for transportation of gases has been increasing to reduce the cost of the overall pipeline system. Along with higher strength, adequate fracture toughness and resistance to plastic buckling are required of pipes installed in earthquake- or frost-prone regions. To get higher strength with adequate deformability in low-alloy pipeline steels, plates for pipes are typically made today by thermo-mechanically-controlled rolling processes, which introduce strong crystallographic texture and anisotropy in the pipes. The plates are then cold-formed into pipes, which introduces further anisotropy and residual stresses in the pipe. In the current work, effects of various steps of the pipe manufacturing process, such as rolling, cold forming, etc., on residual stress, hardening moduli, plastic anisotropy, and eventually, to the buckling resistance of the pipe, are studied. Effects of various types of geometric perturbation on plastic buckling response of pipes are also studied.
(cont.) Due to the crystallographic texture and cold-forming, crystal plasticity-based constitutive models instead of Mises plasticity-based constitutive models may be better suited to model the pipe. In the current work, crystal plasticity-based material models are used to predict the buckling response of pipes. Results show that the buckling strain in uniaxial compression, predicted using a crystal plasticity-based model, is - 20% less than the one predicted using an "equivalent" Mises plasticity-based model, for a pipe with d/t ratio of 51. Further results show that variation in material properties and residual stresses caused by cold forming reduces the buckling strain by - 30%, for a pipe with d/t ratio of 51.
by Vaibhaw Vishal.
Ph.D.

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Cai, Minghao. "Acousto-Plastic deformation of metals by nonlinear stress waves." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1156445865.

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O'Brien, Evan Daniel. "Welding with Low Alloy Steel Filler Metal of X65 Pipes Internally Clad with Alloy 625: Application in Pre-Salt Oil Extraction." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469018389.

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50

Kalhor, Roozbeh. "Accelerated Testing Method to Estimate the Lifetime of Polyethylene Pipes." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/79944.

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The ability to quickly develop predictions of the time-to-failure under different loading levels allows designers to choose the best polymeric material for a specific application. Additionally, it helps material producers to design, manufacture, test, and modify a polymeric material more rapidly. In the case of polymeric pipes, previous studies have shown that there are two possible time-dependent failure mechanisms corresponding to ductile and brittle failure. The ductile mechanism is evident at shorter times-to-failure and results from the stretching of the amorphous region under loading and the subsequent plastic deformation. Empirical results show that many high-performance polyethylene (PE) materials do not exhibit the brittle failure mechanism. Hence, it is critical to understand the ductile mechanism and find an approach to predict the corresponding times-to-failure using accelerated means. The aim of this study is to develop an innovative rupture lifetime acceleration protocol for PE pipes which is sensitive to the structure, orientation, and morphology changes introduced by changing processing conditions. To accomplish this task, custom fixtures are developed to admit tensile and hoop burst tests on PE pipes. A pressure modified Eyring flow equation is used to predict the rupture lifetime of PE pipes using the measured mechanical properties under axial tensile and hydrostatic pressure loading in different temperatures and strain rates. In total, the experimental method takes approximately one week to be completed and allows the prediction of pipe lifetimes for service lifetime in excess of 50 years.
Master of Science

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