Academic literature on the topic 'Wrapping curve'
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Journal articles on the topic "Wrapping curve"
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Huo, Hong Yuan, Chen Jie Cao, Li Sun, Li Sha Song, and Tong Xing. "Experimental Study on Full Stress-Strain Curve of SFRC in Axial Tension." Applied Mechanics and Materials 238 (November 2012): 41–45. http://dx.doi.org/10.4028/www.scientific.net/amm.238.41.
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The tests were carried out to study the effects of the fraction of steel fiber by volume and the thickness of cement paste wrapping steel fibers on the axial tensile properties of steel fiber reinforced concrete (SFRC). The strength grade of SFRC was CF40 with the fraction of steel fiber by volume varying from 0.5% to 2.0%, and the thickness of cement paste wrapping steel fibers varying from 0.8mm to 1.2mm. The tests were conducted by WAW-600 electric-hydraulic servo-type test machine. The results show that the axial tensile properties such as the axial tensile strength, the fullness of stress-strain curve, the tensile energy and the axial tensile toughness ratio are all improved obviously by the adding of steel fiber in concrete. The reasonable thickness of cement paste wrapping steel fibers is 1.0mm. The formulas for stress-strain relationship of SFRC in axial tension are proposed.
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Liu, Jian, Shiqing Xin, Xifeng Gao, Kaihang Gao, Kai Xu, Baoquan Chen, and Changhe Tu. "Computational Object-Wrapping Rope Nets." ACM Transactions on Graphics 41, no. 1 (February 28, 2022): 1–16. http://dx.doi.org/10.1145/3476829.
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Wrapping objects using ropes is a common practice in our daily life. However, it is difficult to design and tie ropes on a 3D object with complex topology and geometry features while ensuring wrapping security and easy operation. In this article, we propose to compute a rope net that can tightly wrap around various 3D shapes. Our computed rope net not only immobilizes the object but also maintains the load balance during lifting. Based on the key observation that if every knot of the net has four adjacent curve edges, then only a single rope is needed to construct the entire net. We reformulate the rope net computation problem into a constrained curve network optimization. We propose a discrete-continuous optimization approach, where the topological constraints are satisfied in the discrete phase and the geometrical goals are achieved in the continuous stage. We also develop a hoist planning to pick anchor points so that the rope net equally distributes the load during hoisting. Furthermore, we simulate the wrapping process and use it to guide the physical rope net construction process. We demonstrate the effectiveness of our method on 3D objects with varying geometric and topological complexity. In addition, we conduct physical experiments to demonstrate the practicability of our method.
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Wang, Yinao. "The grey interval prediction method and its prediction accuracy." Grey Systems: Theory and Application 4, no. 2 (July 29, 2014): 339–46. http://dx.doi.org/10.1108/gs-05-2014-0013.
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Purpose – The purpose of this paper is to discuss the interval forecasting, prediction interval and its reliability. When the predicted interval and its reliability are construction, the general rule which must satisfy is studied, grey wrapping band forecasting method is perfect. Design/methodology/approach – A forecasting method puts forward a process of prediction interval. It also elaborates on the meaning of interval (the probability of the prediction interval including the real value of predicted variable). The general rule is abstracted and summarized by many forecasting cases. The general rule is discussed by axiomatic method. Findings – The prediction interval is categorized into three types. Three axioms that construction predicted interval must satisfy are put forward. Grey wrapping band forecasting method is improved based on the proposed axioms. Practical implications – Take the Shanghai composite index as the example, according to the K-line diagram from 4 January 2013 to 9 May 2013, the reliability of predicted rebound height of subsequent two or three trading day does not exceed the upper wrapping curve is 80 per cent. It is significant to understand the forecasting range correctly, build a reasonable range forecasting method and to apply grey wrapping band forecasting method correctly. Originality/value – Grey wrapping band forecasting method is improved based on the proposed axioms.
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Obaidat, Yasmeen Taleb. "Evaluation for RC Column Confined Partially with Externally FRP Wrapping Sheet Using Nonlinear FE Analysis." Materials Science Forum 972 (October 2019): 129–33. http://dx.doi.org/10.4028/www.scientific.net/msf.972.129.
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Little research has been carried out in validating, fiber reinforced polymer (FRP) concrete strengthened column and the effective using partial wrapping. Also the effect of several parameter on strengthen column using the partial wrapping sheet of desired width and thickness around column have not been found out. To this end, a nonlinear 3D finite element model has been developed in current study for CFRP strengthened reinforced concrete column to simulate the behavior accompanied by the effect of partial wrapping with emphasis on load capacity and failure mode. The finite element simulation of CFRP strengthened RC columns is performed using commercial finite element program ABAQUS. Modelling was conducted on reinforced concrete columns with dimensions of 160 x 250 x 960 mm. The finite element model incorporates the nonlinear material behavior of concrete, bilinear stress-strain curve of steel and linear elastic behavior of CFRP material. The concrete was modeled using a plastic damage model. The performance of the FE model was studied by simulating experimental columns from the literature. The load, and strain of CFRP obtained from the FE study were compared with the corresponding experimental results. The FEM results agreed well with the experiments. In addition, to enhance our understanding of the behavior of strengthened reinforced concrete column capacity using partial wrapping the effect of changing the spacing between the CFRP sheets and number of layers were examined. The increase number of layers and decrease spacing give a higher ultimate load capacity, and delay the failure.
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Abd Ghani, Kay Dora, Nor Hayati Hamid, and Muhd Salmizi Jaafar. "Load versus Displacement Validation between Ruaumoko Hysteresis Program and Experimental Work on CFRP Retrofitted Precast Beam-Column Exterior Joint." Key Engineering Materials 594-595 (December 2013): 390–94. http://dx.doi.org/10.4028/www.scientific.net/kem.594-595.390.
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This paper presented the load versus displacement curve for experimental work and validated with modeling results. A full-scale specimen which representing retrofitted precast RC beam-column exterior joint with corbels was tested in the laboratory under reversible lateral cyclic loading until ±1.75% interstorey drift. The specimen was rehabilitated by using Carbon Fiber Reinforced Polymer (CFRP) wrapping method. Modeling work was carried out using Ruaumoko Hysteres Program. A curve representing load versus displacement for beam-column exterior joint is generated using Pampanin Reinforced Concrete Beam-Column Joint Hysteresis rule with reloading slip factor. The modeling result was compared with the load versus displacement curve obtained from experimental work. It was found that the hysteresis loops exhibited good agreement between experimental and modeling results. The effective stiffness, displacement ductility and equivalent viscous damping for the specimen were also discussed and compared.
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Li, Jian Hui, Ying Li, and Zong Cai Deng. "Envelope Response of Corroded RC Circular Columns Strengthened with Hybrid Fiber Reinforced Polymers." Advanced Materials Research 255-260 (May 2011): 3124–28. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.3124.
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Corroded RC columns do not possess necessary ductility to dissipate seismic energy during a major earthquake, the study investigates the use of hybrid fiber reinforced polymer (FRP) wrapping as a method of retrofitting non-ductile corroded RC columns, and a model to determine the envelope response of RC corroded columns strengthened with hybrid FRP are presented based on cross-section analysis for undamaged RC element. The results show that the technique of strengthening corroded RC column with hybrid FRP is quite effective, the envelope curve estimated using the linear plane assumption with modification by reinforcement slip model, may still be used as the envelope curve of RC corroded columns strengthened with hybrid FRP, a good agreement between analytical and experimental results is observed.
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Lu, Jiancheng, Yujun Qi, Yifei Li, and Xuxu Wang. "Axial Compressive Performance of a Composite Concrete-Filled GFRP Tube Square Column." Applied Sciences 11, no. 15 (July 23, 2021): 6757. http://dx.doi.org/10.3390/app11156757.
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A composite concrete-filled glass fiber reinforced polymer (GFRP) tube square column is a new type of composite column, where GFRP is externally wrapped over several GFRP square tubes to form a multicavity GFRP tube, and then concrete is poured inside. External GFRP wrapping methods can be divided into two types: entirely wrapped and strip-type wrapped methods. The former is superior to the latter in terms of performance under stress. However, difficulties are introduced in the construction process of the former, and substantial materials are required to wrap the entire structure. To examine the axial compressive performance for this new type of composite column and the impact of the wrapping method, we designed and fabricated one type of entirely wrapped composite column and two types of strip-type wrapped composite columns with clear spacings of 85 mm and 40 mm, respectively, and performed static axial compression tests. Through tests and numerical simulations, we obtained the failure mode, load–displacement curve, and load–strain curve of the specimen, and analyzed the impact of the externally wrapped GFRP on the mechanical behavior of the composite column. The results show that the composite column reached the peak load before the fracture of the GFRP tube fiber occurred, and the bearing capacity declined sharply to approximately 75% of the peak load after the fiber fractured, then entered a platform section, thereby displaying ductile failure. As the wrapped layers of GFRP strips increased, the load capacity of the specimen exhibited a linear growth tendency. Compared with the performance of the entirely wrapped method, the load capacity of the specimens in the W5040 group declined 9.8% on average, and the peak efficiency of the GFRP strips increased by 50%, thereby indicating that the use of appropriate GFRP layers and strip distance intervals can ensure the appropriate bearing capacity of composite columns and full utilization of GFRP material properties.
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Kwahk, Imjong, Kwang-Yeun Park, Ji-Young Choi, Hungjoo Kwon, and Changbin Joh. "Non-Destructive Evaluation for Sectional Loss of External Tendon of Prestressed Concrete Structures Using Total Flux Leakage." Applied Sciences 10, no. 21 (October 22, 2020): 7398. http://dx.doi.org/10.3390/app10217398.
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A non-destructive evaluation method is proposed to identify the sectional loss of the external tendon of prestressed concrete structures by detecting the change of the magnetic flux in the external tendon exposed to a magnetic field. The method uses a solenoid-shaped device with two coils: a primary coil for producing magnetic field and secondary coil for damage detection, wrapping the external tendon. A current applied to the primary coil in the device causes the magnetic field. Then, the change in the magnetic flux by the damage in the external tendon is detected by the variation of the voltage in the secondary coil in the device as the device moves along the tendon. An alternating current is applied to the primary coil to minimize the effect of the moving speed of the device. As a result, the damaged area can be detected with a low-level energy current. In addition, a wrapping solenoid-shaped device that is easy to disassemble and assemble was developed for in situ inspection. The measured signal from the secondary coil has a sinusoidal form with the same frequency as the applied current to the primary coil, and the peak curve of the measured signal provides enough information to detect the damage. It is shown that the proposed method can quantitatively identify one or multiple damaged-tendon locations as well as damages of at least 2 cm.
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Ramaswamy, Anandakumar, Selvamony Chachithanantham, and Seeni Arumugam. "Performance of BFRP Retrofitted RCC Piles Subjected to Axial Loads." Advances in Materials Science and Engineering 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/323909.
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This paper deals with the behaviour of basalt fibre reinforced polymer (BFRP) composites retrofitted RCC piles subjected to axial compression loads. Currently the awareness of using FRP increases rapidly in engineering fields and also among public. Retrofitting becomes vital for aged and damaged concrete structures, piles, and so forth, to improve its load carrying capacity and to extend the service life. The load carrying capacity of piles retrofitted with basalt unidirectional fabric was studied experimentally. 15 nos. of RCC end bearing pile elements were cast with same reinforcement for axial compression experiment. Three piles were used as conventional elements, another 3 piles were used as double BFRP wrapped pile elements, and remaining 9 piles were used as retrofitted piles with BFRP double wrapping after preloaded to 30%, 60%, and 90% of ultimate load of conventional element. The effects of retrofitting of RCC pile elements were observed and a mathematical prediction was developed for calculation of retrofitting strength. The stress vs. strain relationship curve, load vs. deformation curve, preloaded elements strength losses are tabulated and plotted. Besides, crack patterns of conventional elements and tearing BFRP wrapped elements were also observed. The BFRP wrapped elements and retrofitted elements withstand more axial compressive load than the conventional elements.
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Ortega Moreno, L., A. Sanz-Garcia, M. J. Fernández de la Fuente, R. Arroyo Solera, M. Chaparro, S. Fernandez-Tome, A. C. Marin, et al. "P113 Serum adipokines as non-invasive biomarker in Crohn’s disease." Journal of Crohn's and Colitis 14, Supplement_1 (January 2020): S192. http://dx.doi.org/10.1093/ecco-jcc/jjz203.242.
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Abstract Background Adipose tissue wrapping the gastrointestinal tract is a risk factor for disease activity in Crohn’s disease (CD). Indeed, adipokines associated to lipid metabolism can modulate local immune responses. However, few studies have investigated the possible association between adipokines and CD. Here, we aimed to evaluate the role of serum adipokines as possible biomarkers in CD. Methods Serum samples were obtained from 18 patients with endoscopically active CD (aCD), 22 patients with endoscopically quiescent CD (qCD) and 36 non-inflamed healthy controls (HC). Serum leptin, ghrelin, resistin and adiponectin were analysed by Multiplex (Bio-Rad, Hercules, CA) in a Luminex 200 system technology. Adipokines means for each group of patients were compared and adjusted by Bonferroni or Wilcoxon tests. Receiver operating characteristic (ROC) curves and the area under the curve (AUC) were carried on to evaluate the discriminatory capacity of the adipokines levels between patients groups. Furthermore, for those adipokines that showed an AUC > 0.7, a binary logistic regression adjusted by possible confounders (i.e. sex, age and BMI) was performed in order to test their possible association with CD. Results No differences were found in age, sex or BMI among aCD, qCD and HC; there was no correlation either among the adipokines analysed. Means distribution for serum resistin was different among aCD, qCD and HC (p = 0.006). However, only comparisons between HC and aCD groups showed significant differences (p = 0.02) in the post hoc test. Serum leptin, ghrelin and adiponectin did not show differences between means. ROC curve for resistin showed an AUC of 0.78, with a standard error (SE) of 0.067 when HC and aCD groups were analysed (Figure 1). Furthermore, in this case, as sensitivity and specificity for Youden index correspond to the resistin median concentration, this value was selected as a cut-off for the binary logistic regression analysis; thus, odds ratio (OR) along with their 95% confidence interval (CI) analysis of high relative resistin levels (values higher than their median) adjusted by age, sex and BMI yielded a value of 5.46 (1.34–22.14) when aCD group was compared with HC group. Comparison between qCD and aCD showed an AUC of 0.70 with an SE of 0.089. However, ROC curve did not show a good accuracy when HC and qCD groups were analysed (AUC = 0.58; SE = 0.08). ROC curves analysis for leptin, ghrelin and adiponectin did not show enough accuracy to discriminate between groups. Conclusion Resistin may modulate the inflammation state in CD and it is probably associated to activity, being this association independent of sex, age or BMI.
Dissertations / Theses on the topic "Wrapping curve"
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Čepil, Jiří. "Optimalizace návrhových prvků pozemních komunikací pomocí vlečných křivek vozidel." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-408021.
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The dissertation deals with application of simulated swept paths of vehicles to road designs. Using software which generates simulated swept paths makes new demands on the designer, but Czech regulations do not stipulate the appropriate method of applying swept paths. The theoretical part of the dissertation analyses the theory of how a vehicle moves when passing through a horizontal road curve and a method of calculating a necessary extent of widening the road. The practical part compares swept paths generated by various software programs and differences between them. In order to verify the shapes and dimensions of the swept paths generated, the swept path of a real vehicle was measured. This swept path was then compared with the one generated, and the differences between them were evaluated. One of the software programs was chosen as a reference program, and its output was applied to a road design pursuant to valid regulations. The results obtained within the dissertation were used to develop certified methodology titled: „Methodology of widening road lanes in horizontal curves and of application of vehicles’ swept paths “.
Book chapters on the topic "Wrapping curve"
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"WRAPPING IT UP." In The Mummy's Curse, 179–90. Routledge, 2006. http://dx.doi.org/10.4324/9780203462867-13.
Full textConference papers on the topic "Wrapping curve"
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Chatzopoulou, Giannoula, Ioannis Skarakis, Spyros A. Karamanos, Nicholas G. Tsouvalis, and Aglaia E. Pournara. "Numerical Simulation of CFRP Reinforced Steel Pipe Elbows Subjected to Cyclic Loading." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63853.
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Strengthening of pipelines and piping systems under extreme loading conditions increases their operation safety level towards safeguarding their structural integrity. Motivated by the structural integrity of pipelines and piping systems, the present study aims at investigating the effect of Carbon Fiber Reinforced Plastic (CFRP) wrapping on the mechanical response of cyclically-loaded steel pipe elbows. Based on experimental testing results, a finite element model is developed, which simulates reinforced and non-reinforced pipe elbows specimens subjected to low-cyclic fatigue. For the description of the material nonlinearities, an efficient cyclic-plasticity material model is also employed, capable of describing both the yield plateau region of the steel stress-strain curve and the Bauschinger effect that appears under reverse plastic loading conditions. The results from the numerical models are compared successfully with the experimental data. Furthermore, a parametric analysis is conducted in order to examine the effect of internal pressure on the structural behavior of unreinforced and reinforced elbows, subjected to cyclic loading.
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Gandham, Naresh Kumar, and Hong Zhou. "Synthesis of Concave Helical Compression Springs." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50800.
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Helical compression springs are used to resist compressive forces or store energy in push mode. They are found in many applications that include automotive, aerospace and medical devices. The common configuration of helical compression springs is straight cylindrical shape that has constant coil diameter, constant pitch and constant spring rate. Unlike cylindrical helical compression springs, concave helical compression springs have a larger diameter at each end and a smaller diameter in the middle of the spring. The variable coil diameter enables them to produce desired load deflection characteristics, reduce solid height, buckling and surging, and keep them centered on a larger diameter hole. The unique features of concave helical compression springs also raise their synthesis challenges. In this paper, a method is introduced to synthesize concave helical compression springs. The variable coil diameter of a concave helical compression spring is described by a spline curve. A cylinder with variable diameter is generated by revolving the spline curve on spring axis. The concave helical compression spring is then modeled by wrapping a spring wire on the variable diameter cylinder. The synthesis of a concave helical compression spring is systemized as the optimization of the geometric control parameters of its wrapped spring wire. A synthesis example is presented in the paper to verify the effectiveness and demonstrate the procedure of the introduced method.
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Mitra, Aniruddha, Sirajus Salekeen, and Mosfequr Rahman. "Fabrication of Polyurethane Based Fabric Composite Shaft and its Experimental Study Under Triple Point Bending." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-88531.
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Semi-rigid urethane based fiber composite shafts are fabricated by high pressure injection molding process. The samples are made in Georgia Southern University’s laboratory where compressed air pressure is effectively used for this purpose. A special manufacturing process is suggested which can be used for mass production of these composites. This unique manufacturing technique creates a composite shaft with a core made of matrix material which is completely wrapped around by a woven fiber cloth with a very strong bonding between core and fibers. Three different types of woven fibers: fiber glass, Kevlar 49, and carbon fibers, are used. Triple point bending tests are carried out to test these three different types of composite samples and also samples made of only base or core material. During the test as the applied load is increased, a linear trend is observed between the load and mid-point deflection of the specimens up to a certain level. Higher load causes separation of fibers and core matrix and followed by local buckling of the separated fibers that are under compression region. This phenomenon brings down the bending stiffness of the composite significantly and it is quite pronounced in the load deflection curve diagram. Failure modes are observed to differ for each of these three types of composite and are discussed in details here. Composites with fiber glass wrapping are found to be the strongest among the three. Future work will involve determining the torsional and fatigue properties, and also the effect of fiber orientations on the mechanical properties of these composites.
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Oancea, Nicolae, and Victor G. Oancea. "A New Method for Modeling of Cutting Tools Associated With Rolling Axodes." In ASME 1998 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/detc98/dfm-5714.
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Abstract Most of the existing methods for determining the profiles of cutting tools that work by wrapping are based on the envelope theory which requires cumbersome analytical formulations associated with the solution of equations not always easy to resolve. This work presents a new alternative method for studying conjugated surfaces associated with rolling axodes. The original meshing surfaces are replaced by a family of curves of substitution which gives a simpler interpretation of the envelope theory. The meshing line and the contact points can be easily determined. An equidistant to the tool profile can be simply calculated which can be very useful in the case of machining with cylindrical abrasive disks. Several examples are shown for rack, shaper and rotational cutters.
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Mensah, Patrick F., Omer Soysal, Guoqiang Li, Amitava Jana, and Michael A. Stubblefield. "Transient Two-Dimensional Numerical Modeling of Asymmetric Curing Process." In ASME 2002 Engineering Technology Conference on Energy. ASMEDC, 2002. http://dx.doi.org/10.1115/etce2002/cmda-29073.
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Modeling of a heat-activated coupling process of fiberglass reinforced epoxy composite pipe with a copper nickel 90/10 (Cu 90% Ni 10%) alloy pipe was investigated in this study. A nonlinear-coupled two-dimensional heat diffusion model was used to capture the essentials of in-situ thermal transport during the curing process through the thickness of the prepreg wrapping layers. The resulting nonlinear boundary value problem was solved using an Alternating Direction Implicit (ADI) finite difference model (FDM). Transient temperature distributions and degree of cure were predicted for the prepreg layers with and without a heating source at the side of the alloy pipe. A reasonable agreement was found between the predicted temperatures and the experimental results. Measures to improve the curing quality of prepreg layers were discussed based on the modeling results.
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Xu, Huazhao, Jianhua Wang, and Ting Wang. "Numerical Investigations of Wake and Shock Wave Effects on Film Cooling Performance in a Transonic Turbine Stage: Part 2 — Unsteadiness Effect in a 2D Rotating Passage." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94545.
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Using the validated CFD model and realizable k-ε turbulence model from Part 1, the unsteadiness effects of shock waves and wake flow on the pressure coefficient and film cooling performance in a 2-D, rotating passage is studied in Part 2. Both time-dependent and time-averaged cooling effectiveness distributions on the rotor under the influence of shock waves and unsteady wake flows are presented with blowing ratios of 0.5, 1.0, and 1.5. The results show that (a) the unsteady wake passing caused by the blade rotation significantly influences the time-dependent pressure coefficients, especially in the forward region downstream of the stagnation point on both the suction and pressure sides on the rotor. This effect can be evidenced by the “wrapping behavior” of a strong vorticity field wrapping around the blade leading edge after the wake hit the blade (b) On the suction side, over the crown area of the rotor, the wake-induced pressure fluctuations are augmented by the weak shock wave emanating from the stator’s trailing edge, appearing as a primary peak followed by a secondary peak. The weak oblique shock wave can be evidenced by the dense Mach contour curves. The effect of the wake (rotational) is distinguished from that of the shock (inviscid and non-rotational) by comparing the pressure gradient field with the vorticity field. (c) Similar effects of passing wakes and shock waves on the surface pressure on a rotor are observed on the film cooling effectiveness, except that these effects are of the same magnitude. (d) The effect of the blowing ratio on the static pressure distribution at the rotor wall is not significant, whereas its effect on the film cooling effectiveness is more pronounced.
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Badaru, Akintunde, Brenton Greska, and Anjaneyulu Krothapalli. "Flow-Field Study in a Microjet PEM Fuel Cell." In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33186.
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Microjets have been implemented into a PEM fuel cell in an attempt to achieve even distribution of reactants and passive cooling of the fuel cell unit and a preliminary investigation of this application has yielded positive results. Unlike conventional reactant supply, the reactant microjets impinge on the back side of the flow field plate before wrapping around and traversing the flow field channels where they are involved in electrochemical activity. However, it was observed that the fuel cell was subject to significant flooding, which limited its continuous operation. This paper discusses the results from an experimental study that has been carried out in an attempt to reduce or eliminate the occurrence of flooding through the use of two different flow-field configurations. Measurements of these flow field configurations, identified as MJFC I and MJFC II, are presented here. MJFC I, the first generation prototype, uses a variant of parallel flow field while MJFC II, the second generation prototype, uses multiple independent serpentine flow field channels. For similar operating conditions, characteristic curves obtained showed that MJFC I is susceptible to flooding while MJFC II has superior water management capability. Secondary tests using Electrode Impedance Spectroscopy confirm these findings.
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Ghosh, S. K., S. K. Mukherjea, and B. N. Datta. "Numerical Study of the Flow in the Wake of an Impulsively Started Rotating and Translating Circular Cylinder." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-37355.
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In the present work, a detailed investigation in the wake region of the flow for the case of a two dimensional, laminar, incompressible flow past a rotating and translating circular cylinder has been carried out by applying a second order time accurate finite difference method using primitive variable formulation for different values of α ranging between 0 and 8 for Re = 200, where α is a nondimensional peripheral velocity of the cylinder. It has been observed that lift coefficient increases monotonically with α. But the effect of rotational speed on the steadiness of the flow is found significantly critical. Within the present range of α it is found that there have been back and forth regimes of unsteadiness in the flow. The flow remains unsteady for α ≤ 1.95, becomes steady for 1.95 ≤ α ≤ 4.33 and is unsteady again for 4.33 ≤ α ≤ 4.73. For α > 4.73 the flow is again steady. It is found that while the first steady regime of flow is characterised by two oppositely rotating static vortices, the second steady regime is characterised by only one rotating static vortex wrapping around the cylinder. It is also found that the nature of two unsteady regimes are not same. Detailed investigation reveals that in the first mode of vortex shedding, vortices are shed alternatively from both top and bottom surfaces, while in the second mode, the shedding occurs only from the bottom surface. Investigation also explains the cause behind increase of lift, decrease of drag with respect to α. From FFT analysis it can be concluded that lift curves corresponding to the first unsteady regime are simple sinusoidal waves, while those corresponding to the second unsteady regime are combinations of different harmonics. On the other hand, simple sinusoidal nature of the drag variation is found only when α is zero. By tracking the vortex shedding process closely, it is observed that during the process of formation, a small anticlockwise vortex is formed inside a large anticlockwise wrapping vortex around the cylinder to result into a higher pressure stagnation region just below the cylinder which in turn, effects maximum lift and detaches the small vortex from the lower surface of the cylinder resulting into vortex shedding from the bottom surface.
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Walsh, William, Sandeep Abotula, and Bharath Konda. "Ring Expansion Testing Innovations: Hydraulic Clamping and Strain Measurement Methods." In 2020 13th International Pipeline Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/ipc2020-9407.
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Abstract Ring expansion testing is one of the three accepted methods in API 5L for the measurement of yield strength for line pipe. The other two are flattened-strap tensile testing and round-bar tensile testing. A novel-concept ring expansion test machine has recently been commissioned which uses hydraulic pressure to clamp the top and bottom pressure-reacting plates rather than a traditional bolting arrangement. The benefit of hydraulic clamping is vastly reduced set-up times. This paper describes the design approach and the pitfalls that were overcome in commissioning the ring expansion test unit. Expansion measurements are taken using two different methods: a chain extensometer and an LVDT with a band wrapping the circumference of the pipe. Both approaches are used simultaneously to generate and compare two stress-strain curves for one pressure test. In addition, a 3-Point contact approach is developed to determine the hoop strain during pipe expansion. The 3-point contact approach is an attempt to infer the full hoop expansion behavior by measuring the radius change over a segment of the circumference. The device has two rollers which contact the pipe surface while a dial indicator midway between measures the radius change. As the pipe expands, the rollers maintain contact with the pipe surface while the dial indicator records the change in radius. Tests are performed on HFI, SAWL, and SAWH pipes ranging in outer diameter from 20-inch (508 mm) to 48-inch (1219 mm) and wall thicknesses from 0.375-inch (9.5 mm) to 0.969-inch (24.4 mm). The differences in the stress-strain behavior of these pipe forms are described and related to the residual-stress profiles generated by their respective manufacturing operations. The comparison to flattened-strap and round-bar tensile results are presented in a companion paper. The results of the 3-Point contact approach show that the radius change during early stages of expansion are not uniform around the pipe circumference and different patterns are observed in the HFI, SAWL, and SAWH pipe forms.