Internal Pressure Research Articles

Development of an improved limit pressure solution for shape-distorted 90o pipe bends with through-wall circumferential cracks

PurposeThis paper presents the approximate limit pressure solution for shape-imperfect and through-wall circumferential cracked (TWCC) 90° pipe bends at the intrados region. Finite element (FE) limit analysis was used to estimate the limit pressure by considering the small geometrical change effects.Design/methodology/approachThree-dimensional (3D) geometric linear FE methodology was implemented to investigate the limit pressure of structurally deformed TWCC 90° pipe bends. The material considered in the analysis is elastic perfectly plastic (EPP). The limit pressure of TWCC shape-distorted pipe bends was predicted from the corresponding internal pressure when von-Mises stress was equal to or just exceeded the material’s yield strength for all the models. The theoretical solution which was published in the literature was used to evaluate the current FE approach.FindingsOvality Co and TWCC at the intrados region caused a considerable impact on pipe bends, while the thinning? Ct produced a negligible effect and hence was not included in the analysis. With the combined effect, the bend portion of pipe bend experiences substantial influence, and the TWCC effect consequently increases with 45o, 60o and 90o crack angles and decreases the limit pressure of pipe bends. An improved closed-form empirical limit pressure solution was proposed for TWCC shape-distorted pipe bends at the intrados region.Originality/valueIn the limit pressure analysis of 90° pipe bends, the implications of structural irregularities (ovality and thinning) and TWCC have not been examined and reported.

Elevated systemic venous pressures as a possible pathology in prepubertal pediatric idiopathic intracranial hypertension

BackgroundPediatric idiopathic intracranial hypertension (IIH) is a rare and challenging condition. As implied by the nomenclature, the etiologies remain unknown, and multiple etiologies are being investigated. In this study, we explored the potential role of increased systemic or cerebral venous pressure in the pathogenesis.MethodAn observational cohort study following the STROBE guidelines, including prepubertal children with clinical symptoms and imaging findings consistent with IIH referred to the neurosurgical department, was conducted. The patients underwent a comprehensive diagnostic protocol, including MRI, continuous intracranial pressure (ICP) monitoring, and endovascular venography with venous pressure measurements.ResultsThe study included 11 consecutive patients (six boys and five girls) with an average age of 2.3 years, and an average BMI of 18.4. Among these, one patient was found to have venous stenosis with a gradient; the other 10 patients presented with normal intracranial anatomy. All patients exhibited elevated venous pressures, with an average superior sagittal sinus pressure of 18.9 mmHg, average internal jugular vein pressure of 17.0 mmHg, and average central venous pressure of 15.9 mmHg. Daytime ICP averaged 12.9 mmHg, whereas nighttime ICP averaged 17.2 mmHg with either A- or B-waves in 10 of the 11 patients. Despite pathological ICP, only three patients had papilledema.ConclusionsAll patients had an increased systemic venous pressure, indicating a possible pathological factor for prepubertal IIH. Additionally, our findings show that young children often only partly meet the Friedman criteria due to a lack of papilledema, emphasizing the need for pediatric-specific diagnostic criteria. Further large-scale studies are needed to confirm these findings and to explore the underlying reasons for this increase in venous pressure and potential new treatment avenues.

Effect of helium bubbles on the mobility of edge dislocations in copper

Abstract Helium bubbles can form in materials upon exposure to irradiation. It is well known that the presence of helium bubbles can cause changes in the mechanical behavior of materials. To improve the lifetime of nuclear components, it is important to understand deformation mechanisms in helium-containing materials. In this work, we investigate the interactions between edge dislocations and helium bubbles in copper using molecular dynamics (MD) simulations. We focus on the effect of helium bubble pressure (equivalently, the helium-to-vacancy ratio) on the obstacle strength of helium bubbles and their interaction with dislocations. Our simulations predict significant differences in the interaction mechanisms as a function of helium bubble pressure. Specifically, bubbles with high internal pressure are found to exhibit weaker obstacle strength as compared to low-pressure bubbles of the same size due to the formation of super-jogs in the dislocation. Activation energies and rate constants extracted from the MD data confirm this transition in mechanism and enable upscaling of these phenomena to higher length-scale models.

Foundational Engineering of Artificial Blood Vessels' Biomechanics: The Impact of Wavy Geometric Designs.

The design of wavy structures and their mechanical implications on artificial blood vessels (ABVs) have been insufficiently studied in the existing literature. This research aims to explore the influence of various wavy geometric designs on the mechanical properties of ABVs and to establish a foundational framework for advancing and applying these designs. Computer-aided design (CAD) and finite element method (FEM) simulations, in conjunction with physical sample testing, were utilized. A geometric model incorporating concave and convex curves was developed and analyzed with a symbolic mathematical tool. Subsequently, a total of ten CAD models were subjected to increasing internal pressures using a FEM simulation to evaluate the expansion of internal areas. Additionally, physical experiments were conducted further to investigate the expansion of ABV samples under pressure. The results demonstrated that increased wave numbers significantly enhance the flexibility of ABVs. Samples with 22 waves exhibited a 45% larger area under 24 kPa pressure than those with simple circles. However, the increased number of waves also led to undesirable high-pressure gradients at elevated pressures. Furthermore, a strong correlation was observed between the experimental outcomes and the simulation results, with a notably low error margin, ranging from 19.88% to 3.84%. Incorporating wavy designs into ABVs can effectively increase both vessel flexibility and the internal area under pressure. Finally, it was found that expansion depending on the wave number can be efficiently modeled with a simple linear equation, which could be utilized in future designs.

Research on the Unsteady Flow Characteristics of Solid–Liquid Two-Phase Flow in a Deep-Sea Mining Lift Pump and Model Experimental Verification

The deep-sea mining lift pump is one of the pivotal components in deep-sea mineral transportation systems and its internal flow is very complex; consequently, unraveling its unsteady flow behavior pattern holds immense practical value. This study adopts numerical methods to analyze the time-averaged distribution characteristics of the internal flow field in mining lift pumps, as well as the flow field’s pulsation intensity distribution characteristics, the vortex’s spatiotemporal evolution process in both moving and static cascades, and the time- and frequency-domain pulsation characteristics of internal pressure in each flow passage component under four different flow conditions are also investigated. The hydraulic properties of mining lift pumps under these four different conditions are also evaluated, and the outcomes are benchmarked against those of numerical predictions. Our findings reveal that the interplay between impeller blades and guide vanes significantly influences the pump’s flow characteristics, with the pump’s unsteady flow influencing its hydraulic properties. Experimental validation of this system confirms that the pump under study is in line with design specifications in terms of hydraulic properties. The method validation test on the prototype pump shows that the SST k-ω model is capable of successfully forecasting instability in the flow features of deep-sea mining lift pumps. These results will serve as a theoretical reference for regulating the flow state inside deep-sea mining lift pumps.

Simulation Analysis and Experimental Investigation on the Fluid–Structure Interaction Vibration Characteristics of Aircraft Liquid-Filled Pipelines under the Superimposed Impact of External Random Vibration and Internal Pulsating Pressure

This paper investigated the fluid–structure interaction vibration response of an aircraft liquid-filled pipeline under external random vibration and internal pulsating pressure. First, the fluid–structure interaction solution is theoretically analyzed, and the advantages and disadvantages of the direct coupling method and the separation coupling method are compared, with the latter chosen as the simulation analysis method in this study. Second, taking the U-shaped oil pipeline of an aircraft engine as an example, simulation modeling was performed to compare and analyze the fluid–structure interaction vibration response of aircraft liquid-filled pipelines under different working conditions, obtaining the vibration response characteristics of stress danger points under various conditions. Finally, a test bench for an aircraft liquid-filling pipeline was built to explore the influence of external random vibrations with different kurtoses, different pipe wall thicknesses and different working conditions on the vibration response danger points of aircraft liquid-filling pipelines, verifying the simulation conclusions and providing a basis for aircraft liquid-filling pipeline design.

Impact of stacking sequence on burst pressure in glass/epoxy Type IV composite overwrapped pressure vessels for CNG storage

The shift from metallic to composite pressure vessels for storing compressed natural gas (CNG) is driven by the goal of reducing environmental impact by using lighter higher-performing structures. This work focuses on enhancing the internal pressure strength of a type IV composite overwrapped pressure vessel (COPV) by optimising the stacking sequence of the overwrapping composite layers. Parametric finite element (FE) models are developed to reveal symmetry effects. In these models, both the thickness build-up and fibre angle variation at the turnaround zones are accurately modelled. Subsequently, the stacking sequence is optimised with the objective function of maximising burst strength. The parametric modelling demonstrates that representing the COPV as an axisymmetric continuum reduces computational costs in 5400× while yielding results comparable to full 3D continuum models. Experimental burst tests are carried out to validate the numerical predictions, and the difference in pressure between them is 12.6 %.

Accurate modeling and safety evaluation of dented pipeline with internal pressure based on reverse modeling technique

ABSTRACT As a common form for pipeline geometric defects, dents can induce the local stress concentration of the pipeline, which would result in the debilitation of the bearing capacity and bring huge safety hazards. In this paper, the accurate surface profiles of dented pipeline are acquired based on the 3D scanning technology and deformation detection technology, respectively. Then, the dented pipeline models are constructed by the reverse modeling technique, and the stress distribution characteristics of the dented pipeline in the operation condition are simulated using ABAQUS. The maximum von Mises stresses of a dented pipeline obtained from two proposed modeling techniques are basically consistent. However, the deformation detection technology can effectively avoid the excavation work for buried pipelines. Therefore, the reverse modeling technique based on the deformation detection technology has strong feasibility in practical projects and significant application value in the safety assessment of submarine pipelines, where excavation work is impractical.

Design and Calculation of Products from Composite Materials Using Software

This article analyzes six types of composite pipes that are good replacements for corrosive steel and metal pipes for oil, gas, and water. The analysis of the six samples of composite pipes was done using the software program Hoffman Engineering, which is intended for the design and calculation of various types of products made of composite materials. For the analysis of the six composite pipes, the same diameter and the same length were taken, and variable parameters are: the type of material from which the composite pipes are made (carbon/epoxy, carbon-glass/epoxy and glass/epoxy), and the angle of winding of the fibers (10º and 90º degrees). Using the Hoffman Engineering software package, an analysis of the durability of the six differently designed composite pipes at high internal pressure was performed. The same conclusion was obtained from all analyses: the high internal pressure resistance of composite pipes is highly dependent on the fiber winding angle and the type of fibers used. Composite pipes obtained with a fiber winding angle of 90º have twice the internal pressure resistance compared to composite pipes obtained with a fiber winding angle of 10º. Composite pipes based on carbon fibers have the highest resistance to internal pressure, then composite pipes based on hybrid materials (glass and carbon fibers) and finally composite pipes based on glass fibers. Finally, a comparison was made with the obtained laboratory results for the same composite pipes. The same conclusion was obtained from all analyses: the high internal pressure resistance of composite pipes is highly dependent on the fiber winding angle and the type of fibers used. The composite pipes obtained by this process are durable and resistant to very high pressures.

Toward monitoring submarine glacier melt using hydroacoustics: The role of timescale in the signal of bubble release.

Submarine glacier melt plays a key role in determining glacier stability and driving glacier mass loss. However, quantifying submarine melt remains challenging due to occupational hazards near glacier termini. One method that has been proposed as a low-cost long-term option for remote sensing, though remains unproven, is to use the sounds of glacier ice bubbles to study submarine melt from afar. Calculating melt rate from bubble acoustics remains complicated because different bubbles produce acoustic energy heterogeneously. This study investigates the physical factors that cause this heterogeneity. A computational method to determine time scales of acoustical excitation and acoustic energy values is proposed and utilized to analyze 203 bubble release events from glacier ice collected in Svalbard, Norway. The distributions of these variables are used to show the existence of two separate types of bubble release events. Additionally, internal pressures are determined for the subset of events with the highest acoustic energy values. No straightforward relationship between time scale of excitation and internal pressure is found. This work begins to untangle the acoustic signal of submarine glacier melt and necessitates further research into the environmental factors modulating bubble release.

Study on the Stress Intensity Factor of Tilt Crack on the Inner Surface of Pipeline

Abstract Cracking is one of the key factors jeopardizing the safe operation of pipelines, and Stress Intensity Factor (SIF) is an important parameter for evaluating the degree of crack danger. Cracks on engineering pipelines often appear in irregular patterns. In this paper, with FRANC3D crack analysis software, SIFs of the circumferential tilt cracks and axial tile cracks on the inner wall surface of a pipe under internal pressure were studied with concentration on the effects of the crack tilt angles. Mode I stress intensity factor weakening effect KI/K0 was defined and influences of the crack tilt angle, pipe and crack size on KI/K0 were investigated. With enough simulation results, empirical formulas for calculating the Mode I SIF for the circumferential or axial tilt crack were obtained by modifying the formulas for calculating the SIF of the crack in AMSE FFS-1.

Study on CL-20 Initiated by Flyer Driven by Copper Azide

Abstract A simulation model of copper azide microcharge driving flyer initiation microscale CL-20 explosive was established, and the action process of copper azide detonation driven flyer initiation microscale CL-20 explosive was numerically simulated by ANSYS/LS-DYNA fluid-structure interaction algorithm. The internal pressure and velocity changes of the flyer during the detonation of copper azide and the internal pressure change of the CL-20 explosive during the detonation were studied. The results show that the error between the experimental and numerical simulation results of the average speed of the flyer is within 10%. This provides a feasible solution for the study of the micro-explosion detonation mechanism by simultaneously analyzing the explosion process of the multi-physical field change law. The numerical simulation results are consistent with the experimental results, indicating that the established simulation model can be used to simulate the detonation process of CL-20 initiated by a flyer driven by copper azide. The copper azide charge, with a diameter of 1 mm and a charge thickness of 0.6 mm, successfully initiates the detonation of the CL-20 explosive.

312. THE VALUE OF DETECTING THE GASTRIC TUBE PRESSURE AFTER MINIMALLY INVASIVE ESOPHAGECTOMY: A PROSPECTIVE, UNCONTROLLED EXPLORATORY STUDY

Abstract Background With the increasing popularity of minimally invasive esophagectomy(MIE), the incidence of postoperative gastric conduit dilation has also shown an increasing trend. The main purpose of this study is to explore the relationship between postoperative tubular gastric dilation and internal gastric tube pressure. Methods In a prospective cohort study from November 2023 to February 2024, 54 patients undergoing MIE were enrolled. Based on postoperative chest X-ray, patients were categorized into acute gastric conduit dilation (Acd) and non-acute dilation (Non-Acd) groups. Gastric tube pressure, including static pressures(SP), peak pressures(PP), and median pressures (MP), was measured postoperatively. Acute gastric dilation was defined as the gastric tube occupying over 40% of the hemithorax on X-ray. We compared the incidence of postoperative complications, surgery-related mortality, readmission rates, and hospital stay durations. Results Of the patients, 19 experienced acute gastric dilation, while 35 did not. The Acd group showed significantly higher SP, PP, and MP (p<0.01). Univariate analysis identified SP, PP, MP, and upper mediastinal pleura reconstruction as risk factors for acute gastric dilation, with SP being a key predictor in multivariate analysis. Patients in the Acd group had longer hospital stays (median 13 days vs. 8 days for Non-Acd). No significant differences were noted in postoperative complications, surgery-related mortality or readmission rates. Conclusion Acute gastric conduit dilation post-MIE is linked to increased gastric tube pressure. Monitoring this pressure is both safe and feasible, offering insights into reducing acute gastric dilation through surgical improvements such as mediastinal pleura reconstruction.

Leveraging Lean and Green Supply Chain Practices for Sustainable Supply Chain Performance: The Moderating Role of Environmental Orientation

Abstract This study investigates the impact of lean and green supply chain practices on business process performance and sustainable supply chain performance. The research utilises the resource-based view (RBV) theory to construct a conceptual model wherein lean and green supply chain practices are employed to augment business processes and sustainable performance. Concurrently, dynamic capabilities theory is applied to signify an organisation’s capacity to adapt and evolve in response to internal and external pressures from customers and competitors. The conceptual model is validated using structural equation modelling with a sample of 170 supply chain practitioners from the apparel and textile supply chain in Jordan. Results indicate that lean practices exhibit no direct impact, whereas green practices significantly influence business process performance and indirectly affect sustainable supply chain performance. Business process performance does not mediate the relationship for lean practices, but it does so for green practices. Moreover, the environmental orientation of both competitors and customers negatively moderates the impact of green practices on business processes and sustainable supply chain performance. These findings contribute to existing literature and underscore the crucial role of green supply chain practices in enhancing sustainable supply chain performance in the apparel and textile industry.

Free Vibrations of Thin-Walled Gas Pipelines Taking into Account the Influence of Longitudinal Force During Trench Laying

A numerical experiment was carried out to determine the frequencies of free oscillations of an inhomogeneous pipeline at various mechanical and geometric parameters.This made it possible to establish the influence of factors such as longitudinal force, thickness of the reinforced concrete shell, internal working pressure and the coefficient of the soil bed on the system’s own vibrations. For calculations, a model of an inhomogeneous cylindrical two-layer shell of finite length consisting of a steel pipe and a protective reinforced concrete layer was chosen.

High frequency venting of MEMS ultrasonic transducers and sensors: materials solutions.

Abstract This paper introduces the concept of ultrasonic venting. Similar to acoustic vents, ultrasonic vents refer to the aperture in air-coupled MEMS ultrasonic transducers (either PMUT or CMUT) intended to allow the equalization of internal and external pressures, the transfer of heat and the pass of ultrasonic waves, while impeding the penetration of fluids or particles that can affect the transducer membrane. To that end, vents are covered with a porous membrane whose properties are tuned to meet the afore mentioned requirements. The main difficulty in ultrasonic venting, compared with acoustic venting, is that the required “transparency” to ultrasonic waves is much more difficult to achieve. This involves two main problems as both transmission loss and frequency distortion are much larger at ultrasonic frequencies than in the audio range. The objectives of this paper are: to measure the response of acoustic venting materials in the ultrasonic frequency range, to determine the usability of these materials in ultrasonic vents, and to extract useful information for the design of efficient ultrasonic venting materials. Transmission coefficient spectra of different acoustic venting materials is measured in the frequency range 0.2 –2.7 MHz. The origin of the ultrasonic losses and frequency distortion are analysed as well as the role of mode conversion, internal interferences, modes interference, etc. Results reveal that none of the acoustic venting materials analysed can be used in ultrasonic venting applications, but the obtained knowledge about the response of these materials in the ultrasonic frequency range permit to advance in the selection of successful candidate materials for this application.

Evaluation method of accelerated aging life of internal pressure seal layer of flexible composite hose

Abstract Aiming at the lack of evaluation methods for the life prediction of the inner pressure seal layer of in-service flexible composite hoses, the accelerated aging test method, which is the same as the transport medium and environmental conditions, and the Arrhenius equation principle are adopted to fit the life curve at different temperatures, so as to solve the problem that the life prediction of in-service flexible composite hoses is not possible at present. It provides the basis for the integrity management of flexible composite hose. The results show that the established aging life prediction model can meet the actual application requirements. The crosslinked polyethylene (XLPE) of internal pressure seal can be used for 76 years.

Hydrogen embrittlement effects on remaining life and fatigue crack growth rate in API 5L X52 steel pipelines under cyclic pressure loading

Transporting hydrogen gas through the existing natural gas pipeline network offers an efficient solution for energy storage and conveyance. Hydrogen generated from excess renewable electricity can be conveyed through the API 5L steel-made pipelines that already exist. In recent years, there has been a growing demand for the transportation of hydrogen through existing gas pipelines. Therefore, numerical and experimental tests are required to verify and ensure the mechanical integrity of the API 5L steel pipelines that will be used for pressurized hydrogen transportation. Internal pressure loading is likely to accelerate hydrogen diffusion through the internal pipe wall and consequently accentuate the hydrogen embrittlement of steel pipelines. Furthermore, pre-cracked pipelines are susceptible to quick failure mainly under a time-dependent cyclic pressure loading that drives fatigue crack propagation. Meanwhile, after several loading cycles, the initial cracks will propagate to a critical size. At this point, the remaining service life of the pipeline can be estimated, and inspection intervals can be determined. This paper focuses on the hydrogen embrittlement of API 5L steel-made pipeline under cyclic pressure loading. Pressurized hydrogen gas is transported through a network of pipelines where demands at consumption nodes vary periodically. The resulting pressure profile over time is considered a cyclic loading on the internal wall of a pre-cracked pipeline made of API 5L steel-grade material. Numerical modeling has allowed the prediction of fatigue crack evolution and estimation of the remaining service life of the pipeline. The developed methodology presented in this paper is based on the ASME B31.12 standard, which outlines the guidelines for hydrogen pipelines with reference to the ASME BPVC Section VIII, Division 3, Article KD-10.

Study on the mechanism of pressure-induced erosion in molten pool of EDM metal

Abstract This study employs molecular dynamics methods to explore the mechanism of pressure-induced erosion due to the pressure differential within and outside the molten pool during the EDM process. Through simulations of the EDM process for metals such as copper and tungsten, it was found that high melting point materials exhibit slow melting and evaporation rates within the molten pool, resulting in lower internal pressures and reduced efficacy in material erosion, thereby exhibiting high erosion resistance. Experimental validation has demonstrated that the machining efficiency of metals increases with the decrease in their melting points, thus confirming the accuracy of the simulation results. This research not only unveils the micro-dynamic mechanisms of material erosion but also provides a theoretical foundation and experimental support for the advancement of EDM technology.

A study on the small failure probabilities of cylindrical composite hydrogen storage tanks using subset simulation

Although composite hydrogen tanks are becoming increasingly intriguing, a detailed structural reliability analysis is still lacking. The current landscape of analysis for pressurised multilayer cylinders, while rich in research, lacks tools to deal with the low probabilities of failure that govern the design of hydrogen tanks. This study presents a computational framework integrating the Subset Simulation method (SS) for assessing the failure probability of composite tanks used for hydrogen storage. To explore how randomness impacts design parameters, this study utilises a limit state equation derived from the thin-walled circumferential model of composite pressure tanks. Five random variables, each with varying coefficients of variation (COVs), are incorporated into the analysis. For comparison and validation purposes, two methods Monte Carlo simulations and FORM have been used. The analysis revealed that SS excels at estimating the low failure probabilities of composite hydrogen tanks, and showed also the feasibility and accuracy of SS in the prediction of burst pressure since good agreement was obtained between the probabilistic approach and the experimental results. Furthermore, the uncertainties related to internal pressure and composite thickness affect significantly the reliability of the structure and can lead to the shrinkage of the safety margin and the failure of the vessel.