Metal Tube Research Articles

A Comparative Study of RCC Pre-Cast and Composite Structure Using Delta Beams

Composite structures are gaining greater recognition these days in production regions. Composite beams like concrete filled metal tube are components with precise performance because of the confinement impact of metal with concrete and layout versatility. The composite shape has extra advantage over RCC body structure. The study about the behaviour and the characteristics of a composite over RCC is the high need. In India, concrete is a very famous material of production, particularly in the case of high-raised building, medium-raised and low-raised buildings. where in structural steel is typically used, the composite production isn't that popular, but it's miles possible that composite creation can be extra useful in the case of medium and high-raised buildings. steel concrete composite creation may be constructed in region of RCC systems to get maximum benefit of steel and concrete, to produce green and low-budget systems. it's miles the selection of the contractor or owner which kind of properties they require within the area and in line with those properties, the sort of material can be selected. This paper is in particular based totally at the assessment of the RCC frame structure with the Composite beam structure by using the delta beam. It is largely focused on the structural behaviour and results are tabulated within the form of comparison.

Experimental results for a MW-scale fluidized particle-in-tube solar receiver in its first test campaign

To advance the development of particle-driven technologies, this study presents experimental results of a megawatt-scale solar receiver installed atop the Themis Solar Tower (France). The whole experimental loop and the solar flux distribution at the receiver aperture are described with the associated instrumentation. The solar receiver is composed of forty 4-meter long metallic tubes, and the irradiated part size is 3 m high and 2.6 m wide. The facility was operated at partial load with a maximum solar power of approximately 800 kW with a particle mass flow rate ranging from 2148 kg/h to 12456 kg/h. The tube wall temperature distribution is presented along with a particle temperature increase that reached 400 °C. The dynamic behavior of the solar loop is detailed, in particular the starting phase. The thermal efficiency of the solar receiver ranges from 35 to 63%. An assessment of the lessons learned during this experimental campaign is offered.

A Novel Efficient Energy Absorber With Necking-Expansion of Foam Sandwich Tubes

Abstract Foam sandwich tube is composed of two tubes and a lightweight foam core possessing various advantages, i.e., low density, excellent mitigation performance and energy absorption, etc. With the hope of enhancing the load bearing and energy absorption capacity of energy absorbers, a novel efficient energy absorber composed of axial necking-expansion deformation mode for sandwich circular tube with metal foam core (SCMF-Tube) by an inner-outer conical-cylindrical die is proposed. Considering deformation modes including necking, stretching, bending, and strain hardening of metal tubes as well as densification of the metal foam core, we established an analytical model of necking-expansion deformation for the SCMF-Tube. Then, finite element (FE) simulations are conducted. Analytical deformation modes, load-displacement curves, and bending radii all agree well with the FE results. Effects of material property and geometry on the necking-expansion deformation of SCMF-Tubes are discussed in detail based on the validated analytical model. Adjusting parameters, such as the wall thickness ratio of the inner tube to the outer tube and the maximum diameter of the die can improve the load bearing and energy absorption capacity of the novel energy absorber. Finally, the specific energy absorption of the SCMF-Tube under necking-expansion deformation is 68% higher than that of the circular metal tube under expansion deformation.

Analytical and Numerical Investigations of Circular Metal Foam Sandwich Tube Under Free Inversion

Abstract The foam sandwich tube contains inner and outer tubes and filling foam. The foam sandwich tube is widely used in engineering, due to its lightweight, high specific strength, energy absorption, and other excellent characteristics. In this paper, the free inversion of the circular metal foam sandwich tube (CMFST) under axial loading is studied analytically and numerically. The plastic deformation occurs in the CMFST, and its main deformation modes include circumferential expansion, radial bending of the CMFST, and compression of the metal sandwich foam. An analytical model for the free inversion of the CMFST under axial loading is established, considering metal tube expansion, the radial bending of metal circular tube wall, and metal foam compression. The commercial abaqus software is adopted to numerically study the free inversion behavior of the CMFST. The analytical predictions agree well with the numerical ones. It is shown that the specific energy absorption (SEA) of the CMFST under free inversion is significantly better than the empty tube. When the non-dimensional foam strength is 0.05, the SEA of the CMFST under free inversion is 107.68% higher than the empty tube. Thus, the metal foam sandwich tube under free inversion is an excellent energy-absorbing device.

Predicting the wrinkling in AA5052 seamless tubes manufactured by free bending forming technology

Wrinkling is a significant defect during forming of thin-walled metallic tubes via free-bending forming (FBF) technology. Thus, it's quite important to predict the wrinkling in the tubes to improve the quality of the final products. Accordingly, new theoretical and numerical frameworks were proposed for predicting the wrinkling of the tubes manufactured via FBF technology. The theoretical wrinkling prediction model is based on the energy criteria and the thin shell theory. The numerical prediction model was constructed on the ABAQUS/Implicit FE code. Besides, The Knoop microhardness test characterized the anisotropy of the tube. The tube's imperfection was introduced to the numerical model through pure bending buckling analysis. The bending experiments were conducted to verify the results obtained from the proposed theoretical and numerical frameworks and showed good agreement with them. Furthermore, it was noticed that the additional axial force in the FBF process reduces the tube's ability to resist wrinkles. The larger additional axial force makes tubes more sensitive to imperfection in free bending than in other bending technologies. The numerical prediction model with the perfect tube exhibits good accuracy in predicting the initiation of the tube wrinkling in free bending but not in terms of the wrinkling shape. The model considering the imperfection can predict the onset and development of wrinkling properly.

Анализ методик расчета теплоотдачи к моторному авиационному маслу марки МС-20 в условиях вынужденной конвекции в кольцевом канале с учетом их верификации с экспериментом

Based on experimental studies of the thermal processes in an annular oil channel with the internal heated replaceable metal tube, an experimental database was created. Experimental values of the heat transfer coefficient in regard to the MS-20 aircraft engine oil under its forced convection at various heat flux densities, pressures and pumping rates were calculated based on the experiment results using the Newton — Richmann formula. The authors of the article also created an experimental formula to calculate the Nusselt number. The results obtained were verified by comparing the experimental research results with results of other authors. Theoretical values of the heat transfer coefficient were obtained from the Nusselt number formulas presented by various authors. Formulas and the Nusselt number calculation formulas were analyzed, as well as the heat transfer coefficient in regard to the liquid heat carriers exposed to their forced convection presented by various authors. Graphs and tables compare calculation results according to the theoretical formulas by various authors and calculation results according to the experimental formula of the authors of the article with results of the experimental study. It was established that the experimental formula of the authors of the article was the most accurate and workable. Recommendations are given for calculating the heat transfer coefficient in regard to the MS-20 aircraft engine oil in the annular channel under various thermodynamic conditions. It is proposed to introduce the methodology in conducting an experimental study and creating experimental formulas for calculating the Nusselt number and the heat transfer coefficient in regard to the MS-20 brand aircraft engine oil in studying the other aviation engine oils.

Overlapping of linear optical spectra in metallic carbon nanotubes, Controlled by applied axial magnetic field and uniaxial strain

The excitons and absorption spectra of M11 and M22 transitions in metallic carbon nanotubes were calculated by the tight-binding model, under the combined effect of axial magnetic field and uniaxial strain. It is interesting to find that the separated absorption peaks induced by axial magnetic field will meet each other when the uniaxial strain is applied. At the same axial magnetic field, the first overlapping point is appeared for Mii−−2 and Mii+−1 exciton with small uniaxial strain, and the biggest uniaxial strain is needed for Mii−−1 and Mii+−2 exciton. When we change the magnitude of the axial magnetic field, the overlapping point displays different variation trend for four separate excitons. This overlapping phenomenon is also occurred for other metallic tubes: with bigger diameter, smaller uniaxial strain is needed. More important is that an useful tool is offered to regulate the optical properties of carbon nanotubes by applying simultaneously the axial magnetic field and uniaxial strain.

An Internal Detector Positioning Method in Oil Pipelines Using Vibration Signal

In-pipe inspection is an important means to ensure the safety of oil pipelines. External positioning technology of the internal detector is a vital component of the pipeline detection system. Due to the shielding effect of the metal tube wall,a great limit will be exerted on the application of general electromagnetic technology to the tracking and positioning of the internal detector. This paper proposes a positioning method of the internal detector in the pipeline based on the vibration signal. Aiming at the actual operation of the internal detection in the project site, a structural model of the internal detector positioning system based on the vibration signal is designed based on the idea of "coarse classification and exact regression". Through the vibration generated by the friction and collision between the detector and the tube wall, the feature extraction scheme of vibration signal based on wavelet packet decomposition is designed, and the precise positioning of the in-pipe detector is realized by using the two stage positioning network of Convolutional Neural Network (CNN) and Recurrent Neural Network (RNN). Finally, the field experiments verify that the positioning method of internal detector designed in this paper has the advantages of high positioning accuracy and strong anti-interference ability.

Efficiency improvement of the solar chimneys by insertion of hanging metallic tubes in the collector: Experiment and computational fluid dynamics simulation

The solar chimney power plant (SCPP) is a straightforward and clean technique to generate electricity from solar radiation. However, this technology still faces major challenges, such as low efficiency, which has hindered its industrialization. This study experimentally develops a novel collector design to improve the solar chimney collector's efficiency. The new design includes metallic tubes as solar radiation absorbers hung from the canopy of the collector. The metallic tubes are open at the top and sealed with transparent sheets at the bottom to decrease the solar radiation reflected into the ambient air. Experimental and 3-D computational fluid dynamics (CFD) analyses are performed to validate the new design. The effects of hanging metallic tubes on temperature and velocity distribution are explored. The temperature increased by about 5 K at the chimney inlet, causing a roughly 8% rise in collector efficiency due to the fact that metallic tubes operate as an extended surface. The impact of various tube geometries on solar chimneys' efficiency is examined. The CFD findings reveal that the metallic tube geometry variation has considerably impacted the collector's efficiency. Thus, the collector efficiency is increased by changing tube diameter by around 33.7%, similar to changing tube length by 30%.

Axial Crushing Behaviors of Metal Density Gradient Foam-Filled Square Taper Tubes: Analytical Model and Numerical Calculation

Abstract Metal tube is a traditional energy-absorbing structure, and metal foam is a lightweight material with advantages, i.e., high energy absorption and high specific strength. The foam-filled square tube can improve crashworthiness and has better energy absorption, which is higher than the sum of the energy absorption of the tube and foam. Axial crushing behaviors of metal density gradient foam (DGF) filled square taper tubes are studied analytically and numerically in this paper. An analytical model is presented to study the crushing behavior of DGF-filled square taper metal tube under axial loading, in which the interaction between square taper tube and DGF is considered. The numerical calculation is conducted, and the deformation mode is obtained. The analytical predictions are well consistent with the experimental and numerical results. The influences of taper angle, foam strength, maximum relative density, and minimum relative density of gradient foam on the compressive behavior of metal DGF-filled square taper tubes under axial loading are considered. It is demonstrated that when the taper angle is less than 85 deg, the average crushing force increases as the minimum density of the DGF increases. However, when the taper angle is greater than 85 deg, the average crushing force decreases with the increase of the minimum density of the gradient. This proposed analytical model can effectively predict the axial crushing behaviors of metal DGF-filled square taper tubes.

Relationship between internal pressure strength of flexible metal tubes and bellows shapes

BACKGROUND: This study is concerned with the development of the hydrogen gas dispenser used in hydrogen stations for fuel cell vehicles (FCV). Most of the current flexible hoses suppling the high-pressure hydrogen gas to FCV are made of rubber and resin-based materials. They are required to have the characteristics of resistance to permeation of the gas and to inhibit the internal fractures known as blisters. If the materials can be replaced with metal materials, those difficulties may be resolved. OBJECTIVE: The relationship between the internal pressure strength of flexible metal tubes and their convolution shapes is investigated by experiments and computer-aided engineering (CAE) analyses. METHODS: Two kinds of stainless steels with high Ni equivalent are used for flexible tubing. The U-shaped bellows and the compressed bellows made by compressing them in the axial direction are fabricated, and then CAE analyses of their internal pressure strength are performed Internal pressure rupture tests are also carried out on both bellows. RESULTS: The internal pressure strength of the compressed bellows with a pitch of 1.6 mm was more than twice that of the U-shaped bellows with a pitch of 4.3 mm. CONCLUSION: It was found that the smaller the pitch of the bellows, the larger the internal pressure strength.

Experimental study of the thermal performance of heat storage-integrated solar receiver for parabolic dish collectors.

Parabolic dish collectors (PDC) efficiently produce hot fluids for medium-temperature applications. Thermal energy storage employs phase change material (PCM) due to its high energy storage density. This experimental research proposes a solar receiver for the PDC with a circular flow path surrounded by PCM-filled metallic tubes. The selected PCM is a eutectic mixture of KNO3 and NaNO3 (60%:40% by wt). At a peak solar radiation of about 950 W/m2, the receiver surface reached a maximum of 300°C. The modified receiver is tested outdoors with water as a heat transfer fluid (HTF). The energy efficiency of the proposed receiver is about 63.6%, 66.8%, and 75.4% for the HTF at 0.111kg/s, 0.125kg/s, and 0.138kg/s, respectively. The receiver's exergy efficiency is recorded at about 8.11% at 0.138kg/s. The receiver with a maximum reduction of CO2 emission is about 1.16 tons recorded at 0.138kg/s. The exergetic sustainability is analyzed using key indicators, like the waste exergy ratio, improvement potential, and sustainability index. The proposed receiver design with PCM effectively produces maximum thermal performance with a PDC.

Analysis of high velocity forming of metallic tubes

Metal forming is vital in many manufacturing industries for resizing and reshaping of raw metallic tubes and sheets. Conventional forming processes like forging, rolling, tube drawing and extrusion are associated with high-cost complex tools which are applicable for specific shape and size. High velocity deformation process utilizes impact energy for forming and deformation takes place at high velocity. This paper analyses the high velocity forming of 6061 aluminium tubes, formed under electromagnetic force. Numerical simulation is used to understand dynamic conditions of electromagnetic compressive forming.

Pitfalls of EUS-guided gastrojejunostomy in a patient with history of Roux-en-Y gastric bypass and a frozen abdomen.

Video 1Case of EUS-guided gastrojejunostomy in a patient with a history of Roux-en-Y gastric bypass and a frozen abdomen.

Mathematical procedure for predicting tube metal temperature in the radiant superheaters of a tangentially and front fired utility boilers

The superheaters can be indicated as one of the most critical components of the utility boilers experiencing highest temperatures. The local overheating of the heat exchangers material is a significant operational issue. The current and future market conditions implicate new unfavourable regimes of boiler operating conditions bringing the need for prediction capability of tube wall temperature in either design or retrofit process. There is a need to obtain a realistic metal temperature distribution based on uneven heat flux absorbed and complex steam flow. The current paper demonstrates a computational methodology of predicting tube metal temperature of radiant superheaters platens. It couples a full scale 3-D boiler simulations based on CFD technique on the combustion side with an in-house 1-D heated pipe flow model of the steam side. The methodology was applied to two different boilers with different firing strategy (front fired and tangentially fired) to demonstrate the model flexibility. The model is capable of identifying the exact location of specific platen in which the metal maximum temperature occurs. A validation study was conducted by utilising the available measurements. The computations are in qualitative and quantitative agreement with measurement. The modelling approach can be easily extended to boilers utilising all types of fuels as well as heat recovery steam generators.

On the crashworthiness performance of thin-walled circular tubes: Effect of diameter and thickness

Thin-walled metal structures are known as an effective solution in absorbing impact energy and reducing the resulting reaction forces. The design of energy absorbers with higher energy absorption capability, lower weight and reaction forces, as well as lower manufacturing cost, has always been of interest. In this study, the effects of diameter and thickness of thin-walled Aluminum tubes on different crashworthiness criteria were investigated. To this end, different geometries were examined by simulating the uniaxial compressive test applying the finite element method. The results revealed that the optimal diameter for a simple circular tube (SCT), assuming constant length and thickness, is the smallest diameter in terms of resistance to global buckling. The SCT with an optimal diameter has the highest specific energy absorption (SEA), the lowest maximum crushing force ( F max ), and the highest crushing force efficiency (CFE). Moreover, in this study, the effect of thickness on the tubular absorber performance was numerically investigated according to four criteria: SEA, F max , CFE, and energy absorption (EA), and the optimal dimensions were obtained. Based on the results, increasing the thickness increases CFE, and increasing the ratio of thickness to diameter (t/D) increases SEA and CFE. Eventually, by applying the regression analysis, two equations were presented to calculate F max and CFE, which can be used to predict the performance of thin-walled metal tubes.

Emission control using Carbon Silencer

: For the purpose of mitigating emission and noise in an automotive exhaust system, a carbon silencer is utilized. It is assembled using a perforated hollow metal tube, external casing, activated charcoal and a solution of limestone. The engine's exhaust pipe is connected to the carbon silencer. The hazardous sulfur oxides and nitrogen oxides elements generated by the engine are filtered by activated charcoal. Compared to sound produced in a traditional silencer, sound produced within limestone water is less audible. This is primarily due to little sprockets in water molecules, which reduces its amplitude and hence the sound level. Due to the presence of activated charcoal which has more surface area than regular charcoal it is known as Carbon Silencer. When tested in a single cylinder 4-stroke petrol engine, the noise and smoke levels are significantly lower compared to a typical silencer. Automobiles contribute the majority of pollutants, which include carbon monoxide (CO), unburned hydrocarbons (HC), nitrogen oxides (NOx), and lead. Other sources include electric power plants, industrial and household fuel usage, trash burning, and industrial processes. Carbon silencers are used to decrease emissions and noise

Experimental and finite element simulation study of the mechanical behaviors of aluminum foam-filled single/double tubes

Aluminum foam-filled tubes are complicated structures created by filling one or more thin-walled metal tubes with varying shapes in cross-sections with aluminum foam. We optimized the structure of aluminum foam-filled tubes using software simulation, compression, and three-point bending experiments. Filling aluminum foam not only improves the axial compressive performance and bending strength of the thin-walled metal tube but also eliminates the disadvantage of the low strength of the aluminum foam. The aluminum foam-filled single tube exhibited significant improvements in load-bearing and energy absorption, with a one-time increase in load-bearing and five times increase in energy absorption compared with an empty tube. The aluminum foam-filled single tube with a smaller diameter-to-thickness ratio has a higher load-bearing capacity. In contrast, the length-to-diameter ratio has a lower impact on load-bearing capacity. Once the filling length reaches the effective filling length, the structure can still support higher loads and effectively reduce its overall weight. The compression and bending properties in the double-tube structure filled with foam aluminum improved significantly compared with the empty tube and single-tube structure filled with aluminum foam. The total compressive energy absorption capacity in the double-tube structure filled with aluminum foam is 2.01 times that of the empty tube and 1.81 times that in the single-tube-filled structure. When the wall thickness of the filled stainless steel tube is 1.0 mm, the total bending energy absorption and the specific absorption energy of the aluminum foam-filled double tube structure are 1.5 and 2.1 times that of the corresponding aluminum foam-filled single tube, respectively.

Levels of Radon in Soils of Dodoma City, Central Tanzania

Purpose: Humans receive radiation doses exceeding fifty percent (50%) of the total dose from natural sources as a result of inhaling radon and thoron gases and their daughters. Radon occurs naturally in soils and can diffuse into indoor environments leading to adverse health effects for inhabitants. In this study, measurement of levels of radon gas in soils was performed with the purpose of categorizing areas and highlighting the likelihood of high levels of radon in indoor environments.
 Design/Methodology/ Approach: The study targeted the environs of Dodoma where the rapid expansion of human settlements is ongoing or anticipated. For easy access and convenience, the study was conducted in areas located along main roads leading to the nearby towns/cities. Sampling was done by inserting the drilling rod to a depth of approximately one meter (1 m) below ground level with the aid of a heavy hammer. The alpha pump was used to suck the soil gas from the ground through a metallic tube (the capillary probe) and pressed it into the ionization chamber of the measuring instrument (AlphaGUARD). Radon concentration was read directly from the instrument’s display.
 Findings: It was found that radon concentrations in soil vary from 18.8 to 233.5 kBq.m-3. Based on the radon risk criterion, surveyed areas range from normal to high radon risk categories.
 Research Limitation/Implication: The study only covered a limited area in Dodoma City, and therefore the results may not be representative of the entire city or even the surrounding regions.
 Practical Implications: This study is useful in categorizing building areas based on radon risk criterion with the purpose of reducing possibilities of radon-related health risks; mainly lung cancer to the population.
 Social Implications: Radon is a proven cause of lung cancer in humans. Therefore, knowledge of radon levels in the study area will help in setting the mitigation measures necessary for public health protection.
 Originality / Value/ Novelty: The study demonstrates an approach for estimating radon levels in soils which is beneficial to current and future researchers, environmentalists and regulators, among others.

Degradation of the internal well equipment steel under continuous service in the corrosive and aggressive environments

Purpose is to analyze steel degradation of the internal well equipment during its continuous service while contacting directly the corrosive environments. Methods. A range of research concerning the damaged metal tubes of the internal equipment for oil and gas wells, in particular regarding continuous service tubing, comprised both standard and specific studies involving different variations of X-ray spectral analysis with the use of scanning electron microscope JSM-35CF (JEOL Company, Japan) and SEM-515 with microanalyzer Link by Philips Company. The studied samples have been made of tubing in the period of the unauthorized and emergency well shutdowns; life of the wells is 0 up to 15 years. To analyze both structure and chemical composition of metal inclusive of such gases as oxygen and hydrogen, chippings were produced mechanically from various parts of tube walls. Findings. X-ray structural studies have made it possible to obtain data confirming cementite decay (Fe3С) in the tube metal during continuous operation of the internal well equipment. X-ray structural analysis methods have helped identify the parameters of crystal lattice of a matrix; and a level of elastic distortions of the lattice (i.e. microstresses of the distortions) has been evaluated as well as carbon distribution within ferrite and cementite. The abovementioned offered the possibility to describe both reason and mechanism of the reduced resistance to corrosion in the context of internal well equipment. Originality. New regularities under cementite decay in tube metal have been identified in addition to changes in the parameters of a crystal a lattice; microstresses of the lattice distortions; and carbon distribution within ferrite and cementite. The aforesaid helps explain in a new way both reason and mechanism of the reduced resistance to corrosion in the context of internal well structures operating continuously in aggressive environments. The basic sources and mechanisms of tube steel degradation, resulting from the metal hydrogenation and oxidation, have been defined which becomes the foundation to develop scientifically the substantiated measures mitigating the negative impact on the condition of the internal well facilities operating continuously in the chemically aggressive environments. Practical implications. Degrading hydrogen effect on the crystal lattice of metal has been proved. The effect creates conditions under which tube structures of oil and gas wells experience their failure.