Tube Wall Thickness Research Articles

A Restoring Force Correction Model for Enveloped Steel Jacket-Confined Seismic-Damaged Rectangular Recycled Aggregate Concrete-Filled Steel Tubular Columns

In order to establish a suitable restoring force correction model for enveloped steel jacket (ESJ)-confined seismic-damaged rectangular recycled aggregate concrete-filled steel tubular (RRACFST) columns, based on experimental research, a study of the seismic performance and parameters of ESJ-confined seismic-damaged RRACFST columns was carried out. The restoring force theory, model test, and OpenSees simulation of ESJ-confined seismic-damaged RRACFST columns were conducted. Firstly, a trilinear model of the skeleton curve and a suitable restoring force model for ESJ-confined seismic-damaged RRACFST columns were established. The results were compared with the model test results, and it was found that the two results had good consistency. Secondly, the initial damage of the RRACFST column was simulated by the reducing material properties method, and a correct numerical model for ESJ-confined seismic-damaged RRACFST columns was proposed. The influence mechanism of seismic parameters of the RRACFST column was clarified. Finally, the seismic parameter combination with the best seismic performance for ESJ-confined seismic-damaged RRACFST columns was established; namely, the replacement rate of recycled coarse aggregate is 50%, the concrete strength is C40, the axial compression ratio is 0.3, the strength of the rectangular steel tube is Q345, the wall thickness of the steel tube is 4 mm, and the slenderness ratio is 7.5.

Waste rubber recycling in concrete-filled steel tube members: Mechanical performance, reliability and life cycle assessment

This paper focuses on the axial compression mechanical performance, reliability analysis and environmental impact of rubber concrete-filled circular steel tube (RuCFST) columns. Initially, the research of the axial compression performance reveals that enhancing the wall-thickness or yield strength of steel tubes variably increases the yield, peak, and ultimate loads of RuCFST columns. The degree of enhancement of each characteristic point by growing the wall thickness of the steel tube is 5 %–44 %, 6 %–44 %, and 9 %–44 %, respectively; while the degree of enforcement is 5 %–55 %, 23 %–53 %, and 24 %–61 %, respectively, upon yield strength increase. Reliability analysis indicates that higher concrete grades decrease the probability of axial compression failure in RuCFST columns. Raising the yield strength and wall-thickness of steel tubes leads to a reduction in the reliability index. Both larger and smaller live-to-dead load effect ratios adversely impact the reliability index. In addition, the life cycle assessment method was used to evaluate the environmental impact of RuCFST columns, and the analysis was made after considering the superposition effect of waste rubber incineration and recycling into rubber aggregates.

Experience of preputiotomy performing in bull with acroposthitis and fibrous affect of penis’ S-shaped curve

The aim of this study was to perform a preputiotomy with the formation of an artificial opening in a breeding bull to realize his reproductive potential. Scientific and production research was conducted in the spring of 2024. In a 3.5-year-old Holstein breeding bull, kept at a breeding station for keeping breeding bulls, acroposthitis and fibrous lesion of the penis in the area of the S-shaped bend were detected due to the developed infectious process caused by Pseudomonas aeruginosa. The resulting pathology prevented the penis from fully extending beyond the preputial sac when collecting sperm for an artificial vagina (the last sperm collection was performed on 02/07/2024). The operation performed consisted of the following stages: insertion of a thick-walled tube into the preputial sac for better orientation in the tissues; making a V-shaped incision of all layers of the prepuce near its fornix; excision of the prepuce section necessary for free removal of the penis when collecting sperm; formation of an artificial opening by connecting the parietal preputial layer to the skin with an interrupted suture. The postoperative period included daily monitoring of the animal's condition, antibiotic therapy (amoxicillin (0.15 g), three injections every 48 hours), and the use of non-steroidal anti-inflammatory drugs (meloxicam (0.002 g), 3 days). A month after the operation, sperm was collected (06.05.2024, three months later) and the presence of all unconditioned reflexes was noted. At the same time, the copulatory reflex was full, painless and ended in ejaculation. The obtained volume of sperm after two mountings was 2.5 ml, the concentration was 1.3x108, the activity was 8 points. Thus, preputiotomy is an effective method for surgical correction of lesions of the preputial sac and adhesions in the area of the S-shaped bend of the penis in breeding bulls.

Study on Crashworthiness of Shrink Tube Anti-Creep Device

Based on the requirements of the narrow installation space of a train end, compact energy-absorbing travel, and huge energy suck, a shrink tube anti-creep device was designed. The crashworthiness of different structures was studied by means of a material test, a trolley test, and numerical simulation. For every 1 mm increase in tube wall thickness, 1 mm increase in the axial length of the friction cone, and 0.01 increase in the friction coefficient, the mean crushing force (MCF) increased by 45.1 kN, 13.5 kN, and 30.5 kN, respectively. When the cone angle of the shrink tube increased from α = 5° to α = 25°, the increase in the MCF with different thicknesses was about 600%. The MCF was most affected by the cone angle, followed by the wall thickness, the friction coefficient, and the axial length of the friction cone. The change in the contact length of the friction cone of the shrink tube under different structural parameters was compared. The contact length decreased with the increase in tube wall thickness and increased with the increase in angle. The variation rule of MCF was obtained to provide a reference for the development of genealogical products.

Eccentric load capacity of ultra-high strength concrete-filled steel tubular lattice short columns

To explore the behavior of ultra-high strength concrete filled steel tubular (UHSC-FST) lattice short columns under eccentric compressive loads, experimental analyses on four specimens and 276 finite element models using ABAQUS were conducted. The study focused on the effects of steel tube wall thickness, concrete strength, steel tube strength, and load eccentricity on failure modes, load-displacement curves, and ultimate load-bearing capacity. Results showed that for columns with minor eccentricity-induced compressive failure, the reduction coefficient of ultimate load capacity has a weak correlation with the parameters. However, for columns with significant eccentricity-induced tensile failure, the reduction coefficient increases with steel tube thickness and strength and decreases with concrete strength. The center-to-center distance of the columns has a minor effect. Based on these findings, a comparative analysis of existing standards was conducted, leading to the development of an accurate method for calculating the ultimate load-bearing capacity of eccentric CFST lattice columns. This method is applicable to various cross-sectional dimensions, material strengths, and steel tube wall thicknesses, with calculation errors within 10 %, ensuring it meets engineering precision requirements.

Image restoration of reflectors by the method of digital aperture focusing in thick-walled pipes of small diameter

In ultrasonic inspection of pipes of various diameters using antenna arrays and arrays, two technologies of reflector image reconstruction are widely used: antenna array focusing technology (PAUT) and digital aperture focusing (DAF) technology. If the tube diameter is larger than a hundred wavelengths, the DAF method can be used to reconstruct the reflector image by taking into account several reflections from the boundaries, assuming that the object of inspection is flat. In this case, the errors in the formation of DAF-image of reflectors will be insignificant. However, if the pipe diameter is several tens of wavelengths and the wall thickness is about half of the pipe diameter, then in this case the geometry of the inspection object must be taken into account to obtain a high-quality DAF-image of the reflectors. The paper considers the peculiarities of image formation at registration of echo signals by an antenna array or matrix, when scanning both on the external and internal surfaces of the object of control. In numerical and modeling experiments it is shown that both antenna array and antenna array can be used to obtain high-quality DAF-image of reflectors when scanning along the outer surface of a thick-walled pipe of small diameter. This is due to the presence of the effect of physical focusing of the ultrasonic field. But when scanning along the inner surface of a thick-walled tube of small diameter, because of the defocusing effect, it is necessary to register echoes with an antenna array to restore the image of reflectors.

Impact of steel tube wall thickness on axial compression behavior of reinforced and recycled aggregate concrete-filled square steel tube short columns

Tests and numerical simulations were conducted to investigate the impact of wall thickness of steel tube on the axial load performance of reinforced and recycled aggregate concrete (RAC)-filled square steel tube short columns (R-RACFST). The test groups consisted of R-RACFST, concrete-filled square steel tube (CFST), and RAC-filled square steel tube (RACFST). Each group had five different wall thicknesses of the steel tube, and the RAC infill was made of 100 % recycled coarse aggregate (RCA). Two replicate specimens were prepared for each group and wall thickness. The tests were used to analyze the effect of steel ratio on failure mode, loading performance, and ductility. The analyses clarified that the reinforcement effectively enhanced the confinement effect on RAC, compensating for the inadequate confinement of the square tubes and the brittleness of the RAC with 100 % RCA. To further understand the acting role of reinforcement, numerical parametric studies were conducted. A novel numerical model for R-RACFSTs was established and verified with the tests. A total of 81 models were then simulated, considering the coupling effects between the wall thickness of the steel tube, the amount of reinforcement, and the strength of RAC. Based on the simulations, the coupling relationship between the steel tube and reinforcement, as well as the optimal range of steel ratio, were determined. Additionally, strength prediction equations were studied and proposed. The findings indicate that it is feasible to fill RAC with 100 % RCA in R-RACFSTs; when combined with appropriate reinforcement, R-RACFSTs with thinner tubes can achieve the same or better performance compared to RACFSTs with thicker tubes; the recommended reasonable range for the steel ratio and corresponding confinement coefficient in R-RACFSTs are 6.4 % to 13.7 % and 1.00 to 2.04, respectively; the predictions proposed are accurate and reliable.

Experimental investigation and numerical simulation of swaging process of tubes for oil country tubular goods

AbstractPremium integrated seamless pipes made from high strength low alloy steels are used to produce oil country tubular goods. Operational requirements of these pipes in petroleum industry lead to an adequate tube end connection with better mechanical strength and sealing properties. Therefore a cold swaging process or calibration of pipe end is necessary for the mechanical threading process of the tube. Applications of typical calibration mandrels result in heavy wear due to higher swaging loads and the optimal necessary geometry of end tube could not be achieved. In this study, a new mandrel geometry with a finished surface was developed to modify the pipe end profile and reduce the wear tool. The investigated pipe made from P110- pipe steel was plastically preformed using a cold swaging process. Experimental measurements of the pipe end geometry after swaging process resulted an increase of the inner tube diameter of approximately 4.9% and an outer tube diameter of 3.7% respectively. Furthermore, a rather constant tube wall thickness was also observed. An Abaqus plug-in was developed to characterize the swaging process of pipe ends. The influence of friction between tool and pipe surfaces on the final geometry of pipe ends and residual stresses in pipe ends due to preforming were numerically predicted. The new designed swaging process resulted a better final pipe end geometry and low tool wear during the preforming of pipe end. The presented plug-in in this work could be used for tool optimization and characterization of swaging process of pipes in oil and gas industries.

A forming method of variable-diameter tubes straightforward from sheet metals

Variable-diameter metallic tubes are extensively used in many industrial applications. They are generally made of pre-formed raw tubes by using the existing processing methods, during which obvious non-uniformity in tube wall thickness inevitably occurs. In this work, a novel method is proposed to form variable-diameter tubes directly from sheet metals by means of the roll-stamp forming technique. A three-pass roll-stamp forming process and corresponding die blocks are designed and implemented to form a demonstrative conical tube. The finite element model of the roll-stamp forming process is established and forming quality is quantitatively evaluated. The initial blank configuration, which is the most important factor for process design, is determined by combining machine learning and multi-objective optimization. The forming experiment is performed, and the conical tube is successfully formed with no significant thinning/thickening of tube wall. The influences of forming direction and conical ratio on the forming process are numerically investigated. The proposed roll-stamp technique provides a novel and effective approach to manufacturing variable-diameter tubes.

Similarity design method and multi-objective optimization of train energy-absorbing tube velocity distortion under axial impact

Thin-walled tubes are commonly used as crucial structures for energy absorption. It is an efficient and convenient research method to establish a small-scale model of the energy-absorbing thin-walled tube for experiments. However, due to the inevitable difference between the design velocity of the test and the actual velocity of the test, it cannot meet the traditional similarity theory. Because of this limitation, this article constructs a similarity design method for the velocity distortion of the multi-cell energy-absorbing tube at the front end of the train under axial impact. Firstly, according to the motion equation of the train system, the design criterion of the similar model under the velocity distortion is derived. Then, the collision mass correction factor is derived based on the elastic-plastic structural energy equation, aiming at the error of the collision peak force and the error of the collision time, the correction factor of the wall thickness of the energy absorbing tube is obtained based on the simulation analysis results. Finally, it is verified that the velocity distortion similarity model can accurately predict the dynamic response of the prototype, and reveals the influence of the mass and wall thickness correction factors on the error.

Preparation, upconversion/downshifting emissions, temperature sensing, and thermochromic properties of one-dimensional Y2Zr2O7:Er3+/Yb3+ tube-in-tube nanostructures via single-nozzle electrospinning

One-dimensional (1D) Y2Zr2O7:Er/Yb tube-in-tube nanostructures were prepared via a simple electrospinning technique with a single nozzle. The diameter of the outer tube of the Y2Zr2O7:Er/Yb tube-in-tube nanostructures is 190–170 nm, the thickness of the outer wall is 22–20 nm, the diameter of the inner tube is 120–100 nm, and the wall thickness of the inner tube is 17–14 nm. The optical properties of the Y2Zr2O7:Er/Yb tube-in-tube nanostructures, including the up-conversion and downshifting luminescence spectra, temperature sensitivity, and thermochromic properties, were studied in detail. Under 980 nm excitation, two weak green emissions at 528 nm and 550 nm, as well as a strong red emission at 650 nm of Er ions, are presented. When excited at 378 nm, the Er ions exhibit strong green emission at 545 nm, two weak red emission peaks at 650 and 680 nm, and near-infrared emission peaks at 1400–1600 nm. With increasing environmental temperature, the luminescence color of the 1D Y2Zr2O7:Er/Yb tube-in-tube nanostructures exhibited a transition from “orange→yellow→ green” when excited at 980 nm. For the 1D Y2Zr2O7:xEr/yYb tube-in-tube nanostructures (x = 0.01, 0.02, 0.03; y = 0.05, 0.10, 0.15), the maximum values of Sr are 2.3 % K−1 under 980 nm excitation and 2.1%K−1 under 378 nm excitation within the temperature range of 303–723 K. This work develops integrated multifunctional optical materials and provides an alternative approach for the fabrication of nanoscale smart platforms, advanced displays, and applications in information security.

Crushing performance of an additively manufactured bio-inspired hybrid energy absorption profile

Abstract Bio-inspired structures have applications in various industries, including automotive, defense, aerospace, and biomedical industries, owing to their combination of high-strength and lightweight properties. To enhance their energy absorption performance, a novel design was developed by integrating a spiral component, inspired by the cross section of the date palm tree trunk (Latin: Phoenix dactylifera), into an empty aluminum tube. The energy absorption performance of a bio-inspired hybrid energy-absorbing profile (BIHEAP) was experimentally and numerically investigated. To ensure the reliability of the numerical studies, finite element models were generated using ANSYS LS-DYNA and subsequently validated through axial crushing tests. Design optimization studies were carried out using surrogate-based models, such as the response surface model and Kriging surrogate models, to increase the energy absorption performance of the BIHEAP, which has three different design variables (spiral revolution, wall thickness, and number of spiral tubes). The initial design of the BIHEAP exhibited a specific energy absorption capacity (SEA) and crush force efficiency (CFE) that surpassed those of the empty aluminum tube by 17.2 % and 4.6 %, respectively. The optimized BIHEAP design demonstrated SEA and CFE values that were 21.4 % and 32 % greater than those of the empty aluminum tube, respectively. When the initial and optimized BIHEAP design were compared, it was found that SEA and CFE was increased by 3.5 % and 26.1 %, respectively.

Performance degradation evaluation of square steel tubes with local penetration damage

Steel tubular structures are susceptible to welding defects, cracking defects and environmental corrosion, which can negatively affect the stability and reliability of structure. This study tested the axial compression performance of twenty-six square steel tubular stubs with localized penetration damage simulated by artificial notch, considering the influence of notch length, orientation, and position. The test results showed that the failure mode of the specimens was dominated by the local buckling along the direction of the notch axis. The failure mode of the specimen with vertical notch showed notch opening, while those with horizontal notch showed notch closing, resulting in the secondary peak value in the load-displacement curve. The existence of local penetration damage reduced the ultimate strength and ductility of the tubular stubs. Compared to the ultimate strength of the specimens with middle notch, those with corner notch were weakened more, up to 27 %. Furthermore, the effects of notch dimension, position, orientation, and tube wall thickness on the axial bearing capacity of square steel tubular stubs are discussed by using a validated finite element model. Owing to the analysis, the ultimate strength of the stubs is reduced by increasing notch length, width and depth, whereas the reduction effect tends to be weakened as the notch orientation angle increases. The notch located in the corner is the most unfavorable for the axial compression performance of the square steel tubular stubs. A semi-empirical formula for evaluating the ultimate strength of square steel tubular stubs with local penetration damage is proposed by introducing the strength reduction factor. An artificial neural network-based ultimate strength prediction model is developed that can consider the effects of wide-range parameters, achieving high accuracy.

Multi-Objective Optimization of Crashworthiness of Shrink Tube Energy Absorption Structure

By means of material testing, truck testing and numerical simulation, the structural parameters of the shrink tube anti-climb device for high-speed trains were determined. The effects of cone angle, tube thickness, friction coefficient and axial length of the friction cone on the crashworthiness of the shrink tube were studied, and the main causes were analyzed. Using cone angle and tube wall thickness as input variables, and peak crush force, mean crash force and specific energy absorption as crashworthiness indexes, a proxy model was constructed using a radial basis function. The global response surface methodology was adopted to optimize the design of the shrink tube’s structural parameters. The results showed that the crashworthiness of the shrink tube was positively correlated with the cone angle, the thickness of the shrink tube and the friction coefficient, and the influence decreased successively, while the influence was negatively correlated with the axial length of the friction cone, which had the least influence. Through the optimized design, the peak force of the shrink tube increased by only 5.41%, while the specific energy absorption increased by 31.03%. Additionally, the mean force was closer to the technical requirements of 600 kN, and the crashworthiness was optimized.

An exact rigid/plastic solution for a thick-walled tube subject to internal pressure and axial load considering a general isotropic hardening law and its application

An exact rigid/plastic solution for a thick-walled tube subject to internal pressure and axial load considering a general isotropic hardening law and its application

Energy absorbing characteristics of pressurized filled tubes under quasi-static loading

This study investigated the crashworthiness performance of tubes filled simultaneously with cellular structures and pressurized air under quasi-static loading by considering the pressure, tube wall thickness, and deformation modes. The compression tests revealed an improvement in the crushing force response to the effects of the filler materials in the tube gap. The absorbed total energy increased by 2 and 3.8 times for pressurized and filled tubes concerning the empty tubes, respectively. It has been demonstrated that the interface effects between the cellular structure and the tube wall play a critical role in the pressure-filled tube’s deformation mode and energy absorption capacity.

Investigating the Mechanical Behavior and Energy Absorption Characteristics of Empty and Foam-Filled Glass/Epoxy Composite Sections under Lateral Indentation.

In this study, the crashworthiness behavior and energy absorption capacity of composite tubes under lateral indentation by steel rods aligned parallel to the specimen axis are investigated using experimental methods. Key parameters such as tube diameter, length, wall thickness, and indenter diameter are systematically examined and compared. Additionally, the influence of polyurethane foam fillers on damage modes and energy absorption capacity is rigorously analyzed. Contrary to conventional findings, smaller diameter specimens filled with foam demonstrate superior energy absorption compared to their larger counterparts, primarily due to enhanced compression of the foam volume. Experimental results reveal a complex interplay of damage mechanisms in composite specimens, including matrix cracking, fiber breakage, foam crushing, foam densification, foam fracture, and debonding of composite layers, all contributing to enhanced energy absorption. Increased tube thickness, length, and indenter diameter, alongside decreased tube diameter, are correlated with higher contact forces and improved energy absorption. Smoother shell fractures are promoted, and overall energy absorption capabilities are enhanced by the presence of foam fillers. This investigation provides valuable insights into the structural response and crashworthiness of composite tubes, which is essential for optimizing their design across various engineering applications.

METHOD FOR PREDICTING THE TECHNICAL CONDITION OF GAS WELL TUBING WITH CORRECTION BASED ON IN-LINE DIAGNOSTICS INFORMATION

The article presents a methodology for monitoring and predicting the technical condition of the suspension of pump-compressor pipes (tubing) of gas wells exposed to carbon dioxide corrosion. The tubing suspension as an object of control and diagnostics is considered, the main loads acting on the object in question are determined, as well as the expression for the equivalent value of the loads. An expression has been obtained for determining the permissible reduction in the tubing wall thickness, provided that the facility remains operational, as well as an expression for determining the total and residual life of the tubing hanger.A comparative analysis of the main methods for determining the corrosion rate of a diagnostic object was carried out, and the optimal method was selected. A method for correcting the results of calculating the corrosion rate using tubing wall thickness values obtained during in-line diagnostics is described.

Post-fire bond-slip performance of concrete-filled stainless steel tube columns

Concrete-filled stainless steel tube (CFSST) structures exhibit superior strength, durability, and fire resistance. These attributes, coupled with their aesthetic appeal and corrosion resistance, make them highly suitable for a broad range of civil engineering applications, ensuring long-term performance and safety across diverse environments. This study investigates the post-fire bond-slip performance of CFSST structures to facilitate the strengthening and retrofitting of fire-damaged CFSST structures. The paper reviews the bond-slip performance and fire resistance of CFSST. A series of fire tests and push-out tests were conducted on 99 circular CFSST stub columns, considering variables such as fire duration, wall thickness of the stainless steel tube, and concrete strength. The analysis covers the slip mechanism, load-slip relationship, sliding load, ultimate displacement, and ultimate bond strength of specimens post-fire. The bonding force between interfaces transitions from cementation to mechanical interlock and ultimately to friction, with some overlap among these mechanisms. A positive correlation exists between sliding load and wall thickness when fire duration is short. For shorter fire durations, fire exposure reduces the ultimate displacement while increasing bond-slip stiffness. Finally, a formula is proposed to predict the ultimate bond strength of CFSST stub columns following exposure to ISO 834 standard fire conditions.

Mechanism and bearing load-capacity of compound stirrup UHPC-encased CFST columns under axial compression

To augment the synergistic performance between the outer reinforced concrete and the core concrete-filled steel tube (CFST) in standard reinforced concrete encased CFST columns, 14 columns underwent axial compression testing. Of these, 12 columns were encased with compound stirrup Ultra-High Performance Concrete (UHPC), one with compound stirrup high-strength cement-based material, and one with ordinary reinforced concrete. The experiment investigated the effects of compound stirrup forms, stirrup spacing, steel fiber content, steel tube wall thickness, outer concrete types, and core concrete strength on the final failure mode, load-displacement curve, strain characteristics, and development pattern of the specimens. Results indicated improved deformation coordination between the outer compound stirrup UHPC and the core CFST in compound stirrup UHPC encased CFST columns. The yield strength of both the compound stirrup and the steel tube was fully developed within the tested parameter range. A calculation method considering the compound stirrups, fiber constrained outer concrete, and the CFST’s contribution ratio was used to predict the ultimate bearing capacity of reinforced concrete encased CFST columns.