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Using the software ANSYS-19.2/Explicit Dynamics, this study performed finite-element modeling of the large-diameter steel pipeline cross-section for the Beineu-Bozoy-Shymkent gas pipeline with a non-through straight crack, strengthened by steel wire wrapping. The effects of the thread tensile force of the steel winding in the form of single rings at the crack edges and the wires with different winding diameters and pitches were also studied. The results showed that the strengthening was preferably executed at a minimum value of the thread tensile force, which was 6.4% more effective than that at its maximum value. The analysis of the influence of the winding diameters showed that the equivalent stresses increased by 32% from the beginning of the crack growth until the wire broke. The increment in winding diameter decelerated the disclosure of the edge crack and reduced its length by 8.2%. The analysis of the influence of the winding pitch showed that decreasing the distance between the winding turns also led to a 33.6% reduction in the length of the straight crack and a 7.9% reduction in the maximum stresses on the strengthened pipeline cross-section. The analysis of the temperature effect on the pipeline material, within a range from −40°C to +50°C, resulted in a crack length change of up to 5.8%. As the temperature dropped, the crack length decreased. Within such a temperature range, the maximum stresses were observed along the central area of the crack, which were equal to 413 MPa at +50°C and 440 MPa at −40°C. The results also showed that the presence of the steel winding in the pipeline significantly reduced the length of crack propagation up to 8.4 times, depending on the temperature effect and design parameters of prestressing. This work integrated the existing methods for crack localization along steel gas pipelines. [ABSTRACT FROM AUTHOR]

In this study, the loads induced by tornado-like vortices on scaled models of eight low-rise residential buildings with real-world shapes in a typical North American community are quantified and compared to the provisions provided by ASCE/SEI 7–22. Physical simulations of the interaction between translating tornado-like vortices representative of EF1-, EF2- and EF3-rated tornadoes and the scaled models were performed in the WindEEE Dome at the University of Western Ontario. Three internal pressure scenarios were numerically simulated. The tornado velocity gust factor was identified as a critical parameter when translating loads from the model to full-scale. The uplift forces on the whole roof in the internal pressure scenarios with one dominant opening are between 44% and 63% higher than the distributed leakage scenario, highlighting the importance of keeping the integrity of the envelope. Revised values of the internal pressure coefficients and external pressure coefficients or correction factors may be used to improve the ability of the standard to provide safer design loads. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries play a vital role in modern energy storage systems, being widely utilized in devices such as mobile phones, electric vehicles, and stationary energy units. One of the critical challenges with their use is the thermal runaway (TR), typically characterized by a sharp increase in internal pressure. A thorough understanding and accurate prediction of this behavior are crucial for improving the safety and reliability of these batteries. To achieve this, two new combined models were developed: one to simulate the thermal runaway and another to simulate the internal cell pressure. The thermal model tracks a chain of decomposition reactions that eventually lead to TR. At the same time, the pressure model simulates the proportional increase in pressure due to the evaporation of the electrolyte and the gases produced from the decomposition reactions. What sets this work apart is the validation of the pressure model through experimental data, specifically for prismatic lithium-ion cells using NMC chemistries with varying stoichiometries—NMC111 and NMC811. While the majority of the literature focuses on the simulation of temperature and pressure for cylindrical cells, studies addressing these aspects in prismatic cells are much less common. This article addresses this gap by conducting pressure validation experiments, which are hardly documented in the existing studies. Furthermore, the model's accuracy and flexibility are tested through two experiments, conducted under diverse conditions to ensure robust and adaptive predictions of cell behavior during failure scenarios. [ABSTRACT FROM AUTHOR]

In this study, the loads induced by tornado-like vortices on scaled models of eight low-rise residential buildings with real-world shapes in a typical North American community are quantified and compared to the provisions provided by ASCE/SEI 7–22. Physical simulations of the interaction between translating tornado-like vortices representative of EF1-, EF2- and EF3-rated tornadoes and the scaled models were performed in the WindEEE Dome at the University of Western Ontario. Three internal pressure scenarios were numerically simulated. The tornado velocity gust factor was identified as a critical parameter when translating loads from the model to full-scale. The uplift forces on the whole roof in the internal pressure scenarios with one dominant opening are between 44% and 63% higher than the distributed leakage scenario, highlighting the importance of keeping the integrity of the envelope. Revised values of the internal pressure coefficients and external pressure coefficients or correction factors may be used to improve the ability of the standard to provide safer design loads.

Abstract With the population ages, many patients are unable to receive comprehensive care, leading to an increase in hazardous incidents, particularly falls occurring after getting out of bed. To address this issue, this paper proposes a method for recognizing bed-exit intentions using an array air spring mattress. The method integrates convolutional neural networks with feature point matching techniques to identify both global and local features of the array air spring. For global features, a one-dimensional focal loss convolutional neural network (1D-FLCNN) model is employed to classify eight internal pressure time series and determine bed-exit status based on global features. For local features, the distribution matrix and feature point matrix of the internal pressure features are extracted to represent the spatial distribution of bed-exit postures. Euclidean distance is utilized to measure the similarity between these matrices and match bed-exit postures. Finally, the recognition results from both feature types are combined using a logical OR operation to produce the final result. Experimental validation confirms that the proposed method greatly improves the anti-interference capability and effectively avoids the problem of non-recognition due to body position and external environment.

Introduction/purpose: There is a growing interest in pipeline integrity and its effects on economic and safety aspects. This study examines the process of corrosion evaluation in order to identify the remaining structural integrity of thin-walled pipelines with corrosion problems. Methods: This work aims to create a corrosion evaluation model that can analyse the deterioration of steel pipes caused by internal pressure. A study utilised the finite element approach to build models for predicting the burst pressure of defect-free straight pipes. The study involved analytical and numerical analysis and used the mathematical extrapolation method. Results: This paper discusses the impact of several factors on the integrity of a pipe, including the depth of defects, the thickness of the pipe, the shape, the size, and the position of faults, as well as the interaction between internal and external defects. Additionally, the influence of external defects on the overall integrity is discussed. Conclusion: It is concluded that the pipeline corrosion failure criterion (PCORRC) model and the presented model align with the analytical solution documented in the literature. This holds immense importance in the field of structural design and safety evaluation.

Copyright of Military Technical Courier / Vojnotehnicki Glasnik is the property of Military Technical Courier / Vojnotehnicki Glasnik and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated the mechanical behavior of silicon carbide fiber-reinforced silicon carbide matrix (SiC f /SiC) cladding using expanding plug tests at 0.5 and 2 mm/min. A three-stage mechanical response for SiC f /SiC was observed, with significant differences in Stage 3 between specimens tested at different rates. Specimens tested at the slower rate (0.5 mm/min) exhibited a characteristic hoop strength of 112.4 MPa and homogeneous destruction behavior, indicative of uniform stress distribution. In contrast, the hoop stress in SiC f /SiC became unsteady at the faster rate (2 mm/min), leading to cracking at a lower nominal proportional limit stress (PLS), structural instability, non-uniform fiber pull-out, and a lower characteristic hoop strength of 92.4 MPa. This suggests that similar phenomena might occur at higher loading rates during internal pressure shock. Therefore, considering the application of SiC f /SiC, to conduct hoop strength testing at faster rates was recommend, such as 2 mm/min. [ABSTRACT FROM AUTHOR]

Unbonded flexible risers have been widely used in the field of offshore engineering in recent years due to their excellent performance in extreme dynamic marine environments, structural compliance, low installation cost, and low quality. And, the internal pressure capacity of unbonded flexible risers is an important indicator of the mechanical performance of unbonded flexible risers. Based on a 2.5-inch, 8-layer typical unbonded flexible riser model, this paper examines the burst failure of the pressure armor layer. Firstly, the balance equation of each separate cylindrical layer and helical layer is derived by functional principle, and then the overall theoretical modeling of an unbonded flexible riser under axisymmetric loads is established by additionally considering the geometric relation between adjacent layers. Secondly, fully considering the complex cross-sectional geometric characteristics and the interlayer's contact with the unbonded flexible riser, a simplified numerical 7-layer model is established by Abaqus, and the material with elastic-plastic properties is conferred. Finally, the validity of the proposed theoretical and numerical methods is verified through the axisymmetric behavior of the test data. Then the burst failure of the pressure armor layer is analyzed based on the material. At an internal pressure of 42 MPa, the pressure armor layer reached its yield stress of 300 MPa, with the entire cross-section yielding between 42 MPa and 42.5 MPa. Additionally, the effect of the friction coefficient is examined. [ABSTRACT FROM AUTHOR]

Brain tissue is one of the softest parts of the human body, composed of white matter and grey matter. The mechanical behavior of the brain tissue plays an essential role in regulating brain morphology and brain function. Besides, traumatic brain injury (TBI) and various brain diseases are also greatly influenced by the brain's mechanical properties. Whether white matter or grey matter, brain tissue contains multiscale structures composed of neurons, glial cells, fibers, blood vessels, etc., each with different mechanical properties. As such, brain tissue exhibits complex mechanical behavior, usually with strong nonlinearity, heterogeneity, and directional dependence. Building a constitutive law for multiscale brain tissue using traditional function-based approaches can be very challenging. Instead, this paper proposes a data-driven approach to establish the desired mechanical model of brain tissue. We focus on blood vessels with internal pressure embedded in a white or grey matter matrix material to demonstrate our approach. The matrix is described by an isotropic or anisotropic nonlinear elastic model. A representative unit cell (RUC) with blood vessels is built, which is used to generate the stress-strain data under different internal blood pressure and various proportional displacement loading paths. The generated stress-strain data is then used to train a mechanical law using artificial neural networks to predict the macroscopic mechanical response of brain tissue under different internal pressures. Finally, the trained material model is implemented into finite element software to predict the mechanical behavior of a whole brain under intracranial pressure and distributed body forces. Compared with a direct numerical simulation that employs a reference material model, our proposed approach greatly reduces the computational cost and improves modeling efficiency. The predictions made by our trained model demonstrate sufficient accuracy. Specifically, we find that the level of internal blood pressure can greatly influence stress distribution and determine the possible related damage behaviors.

Lithium-ion batteries play a vital role in modern energy storage systems, being widely utilized in devices such as mobile phones, electric vehicles, and stationary energy units. One of the critical challenges with their use is the thermal runaway (TR), typically characterized by a sharp increase in internal pressure. A thorough understanding and accurate prediction of this behavior are crucial for improving the safety and reliability of these batteries. To achieve this, two new combined models were developed: one to simulate the thermal runaway and another to simulate the internal cell pressure. The thermal model tracks a chain of decomposition reactions that eventually lead to TR. At the same time, the pressure model simulates the proportional increase in pressure due to the evaporation of the electrolyte and the gases produced from the decomposition reactions. What sets this work apart is the validation of the pressure model through experimental data, specifically for prismatic lithium-ion cells using NMC chemistries with varying stoichiometries—NMC111 and NMC811. While the majority of the literature focuses on the simulation of temperature and pressure for cylindrical cells, studies addressing these aspects in prismatic cells are much less common. This article addresses this gap by conducting pressure validation experiments, which are hardly documented in the existing studies. Furthermore, the model’s accuracy and flexibility are tested through two experiments, conducted under diverse conditions to ensure robust and adaptive predictions of cell behavior during failure scenarios.

A polyethylene pipe reinforced by winding steel wires (PSP) consists of steel wires and high- density Polyethylene (HDPE). Due to its unique structure and combination of material, the PSP possesses excellent mechanical properties, and it has been widely used in many fields as a buried pipe. Foundation settlement is an evitable loading, and strength failure of buried PSP sometimes occurs due to the foundation settlement. In this paper, numerical investigation of failure behavior of buried PSP was conducted. Firstly, groups of uniaxial tensile tests were carried out to acquire the rate-dependent constitutive equation of the HDPE. Secondly, finite element model of PSP embedded in soil subject to foundation settlement was established. Steel wires are represented by truss elements, and HDPE pipes were modeled with solid elements. The steel wires are built in a spiral structure similar to the real steel-wire mesh of PSP. The effect of the nonlinear material property of components were considered in the model, as the tensile curves were input into the model. The PSP was buried in soil, and foundation settlement was applied on a part of the soil's top surface as the displacement boundary condition. Due to the great ductility of HDPE, the steel wires broke prior to the HDPE, so the maximum stress of steel wires was used as the failure criterion of PSP. Once the maximum stress of steel wires exceeds the ultimate strength, PSP was considered to have failed. Based on this model, the stress distribution along PSP was investigated with various internal pressure and settlement displacement. The combined influence of the internal pressure and foundation settlement on PSP failure behavior was analyzed, and the location where failure most possibly occurred was determined under different loading conditions. Furthermore, the influence of different structural parameters of PSP and soil was discussed. [ABSTRACT FROM AUTHOR]

To address the issues of the poor corrosion resistance and the low safety of the metal pipes used for oil and gas transportation, a glass-fiber-reinforced polyethylene thermoplastic composite pipe was developed. The finite-element analysis was employed to investigate the internal pressure resistance of each layer of the pipe. The impact of the winding angle, layer number, and diameter-to-thickness ratio were investigated. The optimum performance of the pipe was achieved when the ± 45° winding angle was set, but the layer number and diameter-to-thickness ratio met the relevant standards. To calculate the maximum bearing pressure of the pipe, two methods were compared: using the Tsai–Hill failure criterion and theoretical calculation of bursting pressure. The analysis revealed that the Tsai–Hill failure criterion better reflected the pipe failure situation. [ABSTRACT FROM AUTHOR]

Copyright of Structural Integrity & Life / Integritet i vek Konstrukcija is the property of University of Belgrade, Faculty of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effect of a temperature change on nonlinear axisymmetric straining of the clamped torispherical shell under internal pressure is investigated. The solution is based on the Kirchhoff–Love hypothesis, taking into account geometric and material nonlinearities. The stress-strain state is examined at cryogenic or elevated temperatures with the temperature-dependent material's characteristics. The analysis has been performed numerically using a combination of linearization and S.K. Godunov's orthogonal sweep methods. Shells made of alloys with various mechanical and thermophysical properties are considered. The effect of the alloy's properties on the nature of the stress-strain state dependence of the torispherical heads on temperature is discussed. [ABSTRACT FROM AUTHOR]

The research results are obtained on the basis of a technique implementing the finite element method for solving problems of strength and stability of discrete-reinforced cylindrical shells made of the composite material, taking into account the momentness and nonlinearity of their subcritical stress-strain state. The stability of an anisogrid circular cylindrical shell made of a composite material under pure bending with internal pressure is investigated. We determine the effect of deformation nonlinearity, reinforcing set stiffness, reinforcement layup angles, shell thickness, and internal pressure on the critical loads of the shell instability. [ABSTRACT FROM AUTHOR]

The article emphasizes the importance and necessity of studying the behavior of automobile tires during operation in the starting mode, from the beginning of driving on “cold” tires to stabilizing its temperature and internal pressure. During this period, the main performance characteristics of the tire can change in a relatively wide range. Therefore, the main focus was on the initial period of driving as the most dangerous from the point of view of predicting the behavior of automobile tires. This article presents the results of analyzing a car tire’s condition and behavior during the starting movement. Features of the main parameter for assessing the stiffness characteristics of the tires were investigated. The research was conducted under conditions of low ambient temperatures during the operation of automobile tires. A numerical-analytical approach was used to estimate the stiffness parameters. Simultaneously, the initial data required for a correct analysis were obtained from the experimental results in actual road conditions. The obtained results allow for providing recommendations on the peculiarities of the automobile tires’ operation under adverse conditions, such as low ambient temperatures.

After a loss of coolant accident (LOCA) in the prestressed concrete containment vessels (PCCVs) of nuclear power plants, the coupling of temperature and pressure can significantly affect the mechanical properties of the PCCVs. However, there is no consensus on how this coupling affects the failure mechanism of PCCVs. In this paper, a simplified finite element modeling method is proposed to study the effect of temperature and pressure coupling on PCCVs. The experiment results of a 1:4 scale PCCV model tested at Sandia National Laboratory (SNL) are compared with the results obtained from the proposed modeling approach. Seven working conditions are set up by varying the internal and external temperatures to investigate the failure mechanism of the PCCV model under the coupling effect of temperature and pressure. The results of this paper demonstrate that the finite element model established by the simplified finite element method proposed in this paper is highly consistent with the experimental results. Furthermore, the stress-displacement curve of the PCCV during loading can be divided into four stages, each of which corresponds to the damage to the concrete, steel liner, steel rebar, and prestressing tendon. Finally, the failure mechanism of the PCCV is significantly affected by temperature.

Abstract Ultrasonic techniques are frequently used in organic molecule conformation analysis. Mixtures of ternary liquid complexes are extensively used for comprehending the strength as well as the characteristics of the interactions between molecules. Experimentally, the thermo physical properties of ternary liquid mixtures such as viscosity (η), density (ρ) and velocity (u) of K-contin, (2-Aminoacetamido)acetic acid and non-aqueous medium were determined over temperature ranges of 298.15, 308.15 and 318.15 K. The experimental data were used to ascertain the thermoacoustic parameters such as free volume, internal pressure, adiabatic compressibility, solvation number, specific acoustic impedance and intermolecular free length. These parameters are more useful for predicting and validating molecular interactions.

Composite vessels are widely used in industry due to their high strength and low weight. In this research, a composite vessel with a metal liner was designed, manufactured, and subjected to internal pressure. The liner of the tank is made of 304 steel, which is screwed on its main part with two patterns of polar and peripheral twisting. In this research, S-glass fibers and epoxy resin 5052 were used. The vessel was subjected to a pressure of 40 bars. Electric strain gauges were used to measure the strain, and stresses were calculated using Hooke's law. In addition to the experimental method, the vessel was also analyzed numerically. ABAQUS (finite element) software was used to examine the experimental data, and the simulation results showed good consistency with the experimental data. The results of the numerical analysis determined the location of the strain gauges. The results of the two methods were compared and discussed. It was found that at low pressures (pressures lesser than 40 bar), composites do not have a significant role in tolerating vessel stress. It has been observed that changes in the geometry of the structure (the joint of the spherical part and the cylinder) resulted in turbulences in the strain and stress curves near the change site.

Investigating the structural behaviour and buckling susceptibility of cylindrical oil storage tanks is crucial for ensuring their safe and reliable operation. In this study, the structural behaviour and buckling susceptibility of closed roof-top cylindrical oil storage tanks under combined internal and external pressure scenarios were investigated using the finite element analysis (FEA) technique. By utilizing the FEA technique, the combined effect of wind-induced pressure of 250 Pa, applied on the outer surface of the tank and internal pressure of 0.5 MPa, applied on the outer surface of the storage was analysed. The result reveals significant stress concentrations and deformation patterns, particularly on the windward side of the tank, thus, emphasizing the susceptibility of the storage tank to buckling under the specified operating conditions for both the filled and half-filled tank; with internal pressure emerging as the primary contributor to mechanical strain and deformation experienced in the tank, while the wind load plays a secondary but significant role in the deformation of the tank. The fe-safe predicted useful life shows that under the specified operating conditions, the filled storage tank will survive 1 429 hours (2 months) while the half-filled tank will survive 3 551 hours (5 months) before failure due to buckling. Thus, the useful life estimation results show the importance of varying oil levels and operating conditions in the structural assessments of storage tanks.

For a typical functional space with dominant opening of a high-rise building, the distributions of mean internal pressure interference factor (IF m) and peak internal pressure interference factor (IF p) are studied in detail by a series of wind tunnel experiments, and the power spectrum densities are employed to present the energy distribution characteristics of the fluctuating internal pressure. For the case of windward wall opening, shielding effects are dominant for the mean internal pressures, while the peak internal pressures show certain amplification effects when the interfering building is located in the domain of {1.5 < y/b > 3} and the maximum IF p is 1.36. For the case of side wall opening, the mean internal pressures only show amplification effects in parallel arrangements for different breadth ratios (B r). However, it is not only in the parallel arrangements but also in the oblique arrangements that the peak internal pressures show amplification effects, where the maximum IF p is 1.21 when B r = 1.0 and 1.2. With respect to the height ratio H r = 0.6, the mean and peak internal pressures have nothing to do with the interfering building for windward wall opening, whereas they are interfered for side wall opening. When H r = 0.8 and x / b > 4, even though the values of IF m are less than 1 while the values of IF p are greater than 1 due to the three-dimensional flow effects. [ABSTRACT FROM AUTHOR]

Structural steel hollow section members are extensively utilized in civil engineering due to their excellent mechanical performance, favourable geometry for corrosion protection, and aesthetic appeal. Degradation in material properties of steel and thermal expansion at high temperatures must be regarded in designs for fire situations. The closed inner space of hollow sections presents challenges at elevated temperatures. The present study examines the effect of expanding air on the stress state in section walls of hermetically sealed circular and rectangular hollow sections. The effect of the gas pressure is calculated analytically and numerically. The pressure of the expanding air may substantially reduce the capacity of a tubular member. The influence on resistance depends on temperature, volume of the air in the tubular member, and geometry of the hollow section. The results of the study indicate that rectangular hollow sections with relatively large width-to-thickness ratios are more sensitive to internal pressure than circular hollow sections. The temperature range where the adverse effect of internal pressure occurs can include realistic critical temperatures in practical design and therefore deserve special attention to ensure the required safety. [ABSTRACT FROM AUTHOR]

Ultrasonic techniques are frequently used in organic molecule conformation analysis. Mixtures of ternary liquid complexes are extensively used for comprehending the strength as well as the characteristics of the interactions between molecules. Experimentally, the thermo physical properties of ternary liquid mixtures such as viscosity (η), density (ρ) and velocity (u) of K-contin, (2-Aminoacetamido)acetic acid and non-aqueous medium were determined over temperature ranges of 298.15, 308.15 and 318.15 K. The experimental data were used to ascertain the thermoacoustic parameters such as free volume, internal pressure, adiabatic compressibility, solvation number, specific acoustic impedance and intermolecular free length. These parameters are more useful for predicting and validating molecular interactions. [ABSTRACT FROM AUTHOR]

Unbonded flexible risers have been widely used in the field of offshore engineering in recent years due to their excellent performance in extreme dynamic marine environments, structural compliance, low installation cost, and low quality. And, the internal pressure capacity of unbonded flexible risers is an important indicator of the mechanical performance of unbonded flexible risers. Based on a 2.5-inch, 8-layer typical unbonded flexible riser model, this paper examines the burst failure of the pressure armor layer. Firstly, the balance equation of each separate cylindrical layer and helical layer is derived by functional principle, and then the overall theoretical modeling of an unbonded flexible riser under axisymmetric loads is established by additionally considering the geometric relation between adjacent layers. Secondly, fully considering the complex cross-sectional geometric characteristics and the interlayer’s contact with the unbonded flexible riser, a simplified numerical 7-layer model is established by Abaqus, and the material with elastic-plastic properties is conferred. Finally, the validity of the proposed theoretical and numerical methods is verified through the axisymmetric behavior of the test data. Then the burst failure of the pressure armor layer is analyzed based on the material. At an internal pressure of 42 MPa, the pressure armor layer reached its yield stress of 300 MPa, with the entire cross-section yielding between 42 MPa and 42.5 MPa. Additionally, the effect of the friction coefficient is examined.

In the course of combat operations, accidental projectile detonation in the mortar barrel channel can occur through the faulty fuze actuation or detonation of two projectiles for the violation of safety measures, viz double charging of the mortar. Barrel rupture occasions pose new challenges for the developers of this weapon to improve the safe operation of mortars. The literature analysis revealed that among the current studies on the stress-strain state of mortar barrels during the projectile explosion in their channel, the results of determining the stresses in the barrel structures capable of withstanding the explosive gas pressure in the channel were absent. Existing mathematical models for evaluating the stress-strain state of a mortar barrel on the projectile detonation in its channel need to be improved. The potentials of developing new approaches to mortar barrel strengthening for combat operations are substantiated. For this, the theory of insert liquid-filled cylinder structures (pipes) is proposed. The internal pressure for those structures is calculated. The mortar barrels can be modified by applying the optimum combination of new materials and modern design circuitry. [ABSTRACT FROM AUTHOR]

As the last barrier to preventing nuclear leakage, it is crucial to enhance the load-bearing capacity and cracking resistance of nuclear containment under internal pressure accidents. Currently, fiber-reinforced polymers are widely used in prestressing concrete structures because of their superior performance, but little research has been conducted on fiber-reinforced polymers in the field of nuclear power plants. In this paper, carbon fiber-reinforced polymer (CFRP) is used as a prestressing tendon material instead of traditional steel strands to study the damage mode of the new type of containment under internal pressure and the feasibility of using CFRP as prestressing tendons. In this study, a three-dimensional refinement model is established, employing ABAQUS 2020 software to analyze and quantify the pressure-bearing performance of nuclear containment with CFRP tendons and finally determine the reasonable range of CFRP tendons that can be used as a replacement. The research shows that the containment with CFRP tendons has an obvious strengthening effect in delaying the generation of cracks, restraining the speed of crack development, reducing the plastic damage of the steel liner, and improving the ultimate bearing capacity of the containment. [ABSTRACT FROM AUTHOR]

In service, the piping components (pipes/elbows) are subjected to different operational loadings such as thermal stress, internal pressure, self-weight, external loading from soil movement, flow induced vibration, vortex induced vibrations and third party damage. Structural integrity assessment of these piping components under postulated accidental conditions is essential for ensuring smooth operation of power plant piping system. In order to understand crack growth behaviour of piping components under operating conditions, fracture studies were carried out on two straight pipes and three elbows of 219 mm OD having circumferential through-wall notch with internal pressure. Fracture tests on pipes were carried out under four-point bending and elbows were tested under in-plane bending. A sealing arrangement consisting of stainless steel plate as backing material and silicon rubber sheet with two-component super strength epoxy based adhesive was used to seal the through-wall notch in the pipes and elbows. The pipe and elbows specimens were filled with water through threadolets and the desired internal pressure was achieved using an automatic high-pressure hydraulic pump. The internal pressure was varied from 10 to 25 MPa. The load carrying capacity of pipes decreased by a factor 1.95 with the increase of initial notch angle from 90.5° to 152.8° under an internal pressure of 10 MPa. In the case of elbows, with an increase of internal pressure from 10 to 25 MPa, load-line displacement corresponding to maximum load increased by 41.1%. Ovalization (intrados-extrados) in the elbows was found to be varying from 2.74% to 6.85% at the end of fracture tests. The pipe specimens have undergone initial stable crack growth followed by crack instability and crack growth deviated from the initial plane of the notch. The collapse load obtained for through-wall cracked elbows under internal pressure was found to be conservative compared to the values obtained using twice elastic slope method. [ABSTRACT FROM AUTHOR]

Fillet welds of airtight welded hollow boxes In steel and steel composite bridge construction, inaccessible box girders provide filigree and resource‐efficient structures. However, due to limited accessibility, inspecting the interior of these girders poses difficulties. As a result, it is necessary for the inaccessible hollow boxes to be airtight welded. This results in pressure variations within the box girder that are influenced by daily and seasonal temperature changes. Furthermore, due to geometric constraints, only two of the four longitudinal welds can be welded from the inside and the outside of the beam. As a result, two of the welds can only be made from the outside, resulting in a single‐sided fillet weld. These one‐sided fillet welds are subjected to unexpected bending stresses due to pressure variations. As part of a research project, numerical and experimental investigations are being conducted to examine the effects of internal pressure and determine the load‐bearing capacity of single‐sided fillet welds. A numerical model is generated and validated, and investigations are carried out using data from weather stations to determine the characteristic value of the internal pressure. Additionally, an initial series of experiments has been conducted to investigate the load‐carrying and rotational capabilities of single‐sided fillet welds. These experiments have shown a significant rotational capacity and increased load‐bearing capacity for the single‐sided fillet welds. [ABSTRACT FROM AUTHOR]

Corrosion is accountable for numerous malfunctions and leakages in gas pipelines. In instances of external corrosion, due to the internal pressure within the pipes, stress concentrations can occur around the corroded areas. These, in the presence of cavities or cracks resulting from corrosion, may amplify the risk of pipeline failure. Consequently, as the wall thickness diminishes due to corrosion, the pipeline's ability to withstand internal pressure declines. In the case of corrosion, the pressure at which a corroded pipe might collapse is significantly lower than that of an uncorroded one. Finite element modeling of corroded pipes with a defect is conducted using the Abaqus software, taking into account the mechanical effects of internal pressure on the gas pipeline structure. Abaqus facilitates the simulation of internal pressure and predicts the behavior of the pipe under pressure conditions. [ABSTRACT FROM AUTHOR]

The internal Xe gas pressure of ultrafine bubbles has been directly measured for the first time by using the γ‐γ angular correlation technique, a well‐known measurement technique in nuclear physics. Radioactive 125Xe (T1/2 = 16.9 h) was induced inside natural Xe‐ultrafine bubbles in water, having an average diameter of 200 nm, by thermal‐neutron irradiation. The asymmetry factor for the 55–188 keV γ‐γ cascade in 125I, followed by the β decay of 125Xe, was used as a probe for the gas pressure in ultrafine bubbles. The internal pressure of the ultrafine bubbles was determined to be 3.6-1.2+1.8 × 105 Pa, lower than those for ultrafine bubbles of N2, CH4, and Ar by Ohgaki (6 × 106 Pa) or that from the Young‐Laplace equation (1.6 × 106 Pa). [ABSTRACT FROM AUTHOR]

A method for solving the problem of relaxing residual stresses after bilateral surface hardening of a hollow cylinder under creep conditions with rigid constraints on the initially specified axial deformation and twist angle is presented. The solution is developed for complex loading regimes including pure thermal exposure, axial loading, torque, internal pressure, and their combinations. A numerical simulation was conducted on a thin-walled cylindrical specimen comprised of X18N10T steel, subjected to a temperature of $T\!=\!600\,^\circ$C, with the inner and outer surfaces subjected to ultrasonic peening. The reconstruction of the initial fields of residual stresses and plastic deformations was carried out based on the known experimental information on the distribution of axial and circumferential stress components in thin surface-hardened areas on the inner and outer surfaces. A phenomenological model of creep of steel alloy X18N10T at $T\!=\!600\,^\circ$C is constructed. The rheological deformation problem within the first two stages of creep was numerically solved using time and radius discretization. The calculations established that the presence of rigid constraints on angular and linear axial displacements resulted in a decrease in the rate of relaxation of residual stresses compared to the case where these constraints are absent. Graphs illustrating the kinetics of residual stresses with respect to the sequence of temperature and loading forces at different timestamps are presented.

The notion that modern buildings should strive to be net-zero energy buildings (NZEBs) is widely accepted. One of the causes leading to high energy usage for space heating, resulting in avoidable carbon emissions, is heat loss via building windows. In order to improve window’s insulation in existing buildings, structured-core transparent vacuum insulation panels (TVIPs) are proposed. TVIPs mainly consist of the structured core material, the low-emissivity film, and the transparent gas barrier envelope. TVIPs have high insulation performance and are inexpensive to manufacture and can be easily installed. Therefore, TVIPs have the potential to improve window’s insulation in existing buildings at a low cost. However, it is necessary to overcome the issue of preventing the pressure rise inside TVIP after vacuum sealing. The authors constructed an experimental setup to quantify the effect of reduction of gas flow rate in TVIP after evacuation by applying the pressure-rate-of-rise-method. In this experiment, a gas barrier film with a straw was used as the vacuum chamber. This could reproduce the pressure increase in the TVIP after sealing and the gas flow rate in the TVIP is evaluated. The experimental result shows that the coated core material and the enclosing getter agent lowered the pressure rise and gas flow rate in TVIP by combining concurrent evacuation and heating. Furthermore, after extending the simultaneous vacuuming and heating period to 8 h and applying the coated core material, and enclosing the getter agent, the internal pressure in TVIP may be lowered to around 1 Pa after 30 min after halting vacuuming. It was confirmed that this pressure satisfied the performance required for TVIPs, and the result was much closer to the realization of TVIPs.

An analytical solution for stresses in a plastically deformed cylinder made of a functionally graded material (FGM) under internal pressure is provided. The cylindrical material is composed of two metal powder particles manufactured using centrifugal casting. While Poisson’s ratio is assumed constant, Young’s modulus is a power function of the radius. The von Mises yield criterion is used under the plane-strain condition. The constitutive material model obeys the Ludwik power law, with the yield strength and work-hardening coefficient as functions of the radius. The stress distributions along the radial direction for the elastic, elasto–plastic field and beyond plastic collapse cases were analyzed. To study the effect on the plastic zone in FGM, in addition to pressure, the gradient index was made to vary from −2 to 2 and different cylinder aspect ratios ranging from 1 up to 3 are considered. A finite-element simulation was run for comparison and validation of the analytical solution. The results showed a good agreement between the two methods.

To overcome the difficulties of forming S-shaped bellows by conventional hydroforming, such as excessive thinning and high internal pressure, and to obtain S-shaped aluminium alloy bellows with large diameters and large expansion rates with minimal reduction in wall thickness, the axial hydroforging method was proposed. In this method, the deformation area produced bending deformation and gradually fitted the die by the end axial feeding under the support of the internal pressure. First, a finite element model was created to investigate the effect of initial internal pressure, final forming internal pressure and axial feeding on the forming quality of 5A03 aluminium alloy S-shaped bellows after springback from the wall thinning ratio and profile accuracy. The results demonstrated that the overall wall thickness of bellows decreased significantly during the bulging and forming stages, whereas the local thickening of the convolution crown occurred during the forging stage, which caused a shift in the position of the maximum wall thinning ratio and a decrease in the wall thinning ratio. The increase in the initial internal pressure increased the maximum wall thinning ratio, convolution height and convolution pitch of the bellows and decreased the convolution thickness. The increase in the final forming internal pressure increased the maximum wall thinning ratio and convolution height of the bellows and decreased the convolution thickness and convolution pitch. The increase in axial feeding increased the convolution height of the bellows and decreased the maximum wall thinning ratio, convolution thickness and convolution pitch. Finally, the experimental setup was designed, and the S-shaped bellows with a small wall thinning ratio and high profile accuracy were successfully manufactured based on the best simulation parameters, which verified the accuracy of the finite element model and the feasibility of the axial hydroforging process. It is essential to develop the bellow hydroforming technology and improve the quality of S-shaped bellows. [ABSTRACT FROM AUTHOR]