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In this study, a novel mechanical fluid–structure interaction (FSI) model is developed to analyze and discuss high-pressure hydrogen flow in a quick coupler under various operating conditions. The transient-state behavior is investigated with respect to different temperatures, hydrogen pressures, and O-ring thicknesses, which directly affect the compression and deformation of the seal. High-pressure hydrogen flow, which may lead to seal damage or failure, is of growing concern due to the increasing use of hydrogen in refueling stations, a sector expected to play a key role in the future of clean energy infrastructure. This study aims to introduce a coupled multiphysics approach by integrating the Finite Element Method (FEM) for solid mechanics with the Finite Volume Method (FVM) for hydrogen flow modeling. The coupling model shows nonlinear interactions between flowing hydrogen and the deformable polymer seal. The results of this work are expected to enhance both the design and performance of high-pressure hydrogen quick couplers, especially for applications in next-generation hydrogen refueling stations, where durability, sealing efficiency and safety are critical.

The properties of materials directly affect the performance of the sealing structures, among which the rubber O-ring seal is one of the most commonly used. In addition, the performance of the O-ring seal is often influenced by the randomness in structure and working conditions, which greatly reduce the reliability of the sealing structure. This paper proposes a reliability-based method to analyze the influence of the randomness in rubber material parameters on the sealing performance of the O-ring. Based on the failure mechanism of the O-ring seal, the stochastic characteristics of the parameters in O-rings are determined through experiments, and the influences of these parameters on the reliability are subsequently analyzed. Moreover, the working conditions are also taken into account to analyze their influence on the performance and reliability of the O-ring seal. The proposed method provides easy access to estimate the reliability of the rubber O-ring seal considering the uncertainty in structure and operational conditions. It is revealed that the material and geometric parameters had greater influence on the reliability of the rubber O-ring.

This paper presents the outcome of the measurement of the tribological characteristic of O-ring seals in the event of operating in conditions with a lack of lubrication. The measurement was carried out on a seal and rod model. The measurement was carried out during the condition of the round cross-section seal sliding on the surface of the piston rod. We analyzed how the friction force during rod movement, which resulted from the cooperation of the sliding nod and the rod, was changing. The experiment was conducted for various rubber materials. The aim of the research was to evaluate the friction reducing capability of graphite in rubbers of commercial sealing parts. Typical materials used for the seal and the materials, which contained the filler in the form of graphite powder, were compared. Synthetic graphite powder with a particle size of 1–2 µm was applied, and nitrile rubber (NBR) and fluoroelastomer (FKM) were compared as typical materials for O-ring seals. In the case of the two tested materials, the addition of graphite powder had an influence on the decrease in the friction force.

Purpose – This paper aims to investigate the suitability of additive manufacturing to produce O-ring seals. Design/methodology/approach – The O-rings were made by the PolyJet-Matrix technology using four different digital materials and then tested for relaxation properties under static and dynamic (sliding) conditions. The approximation of the relaxation curves involved modelling with a Prony series. Findings – The PolyJet-Matrix technology offers new opportunities to model elastomeric elements, with examples being the O-rings produced and tested for their relaxation properties. Describing the behaviour of the particular materials fabricated with this technology by using relaxation functions will extend the knowledge base on digital materials. Research limitations/implications – The four types of photopolymers used in the experiment differed in viscoelastic properties. The analysis of the stress relaxation of the O-ring models was performed at four different step displacements of the loading element. Practical implications – The test results may be useful for the design of O-ring seals made of new elastomeric materials. The relaxation properties of the O-rings made of such materials can be applied to analyse the dynamics of seals, for instance, face seals. Originality/value – The originality of the work lies in the use of digital materials to design and produce elastomeric elements with different relaxation properties, which was confirmed by the test results. This paper presents results of a relaxation analysis for a ring model and the material that the ring is made of. It also discusses how 3D printing and digital materials can be applied in practice.

In order to study the sealing performance of a rubber O-ring coated with fluoride plastic, a two-dimensional axisymmetric nonlinear contact model was established in this paper. The effects of different medium pressures and compression ratios on the stress and sealing performance of the coated O-rings were analyzed, and the performance differences between the coated O-rings and ordinary rubber O-rings were compared. The results show that the contact pressure of both increases with the increase of medium pressure, and the compression ratio has little effect on the overall stress of the two types of seals. Under the same external dimensions, the contact pressure of the coated O-rings is higher than that of ordinary rubber O-rings, but the contact surface length of the latter is about 1.4 times that of the former. Finally, this paper conducts a comparative analysis of the influence of two different coating materials on the sealing performance.

Interfacial surface roughness can result in fluid leakage of seals, and in the design of seals it is standard to give an upper limit for the surface root-mean-square (rms) roughness amplitude h rms . However, h rms is determined mainly by the long-wavelength roughness, which is (nearly) irrelevant for the sealing. I discuss the parameters which determine the leakage of seals, and present results for static rubber seals with circular cross-section (like rubber O-rings). I also study the influence of the fluid pressure on the interfacial surface separation and the leakrate. Graphical Abstract

During cell division, remodelling of the nuclear envelope enables chromosome segregation by the mitotic spindle 1 . The reformation of sealed nuclei requires ESCRTs (endosomal sorting complexes required for transport) and LEM2, a transmembrane ESCRT adaptor 2 – 4 . Here we show how the ability of LEM2 to condense on microtubules governs the activation of ESCRTs and coordinated spindle disassembly. The LEM motif of LEM2 binds BAF, conferring on LEM2 an affinity for chromatin 5 , 6 , while an adjacent low-complexity domain (LCD) promotes LEM2 phase separation. A proline–arginine-rich sequence within the LCD binds to microtubules and targets condensation of LEM2 to spindle microtubules that traverse the nascent nuclear envelope. Furthermore, the winged-helix domain of LEM2 activates the ESCRT-II/ESCRT-III hybrid protein CHMP7 to form co-oligomeric rings. Disruption of these events in human cells prevented the recruitment of downstream ESCRTs, compromised spindle disassembly, and led to defects in nuclear integrity and DNA damage. We propose that during nuclear reassembly LEM2 condenses into a liquid-like phase and coassembles with CHMP7 to form a macromolecular O-ring seal at the confluence between membranes, chromatin and the spindle. The properties of LEM2 described here, and the homologous architectures of related inner nuclear membrane proteins 7 , 8 , suggest that phase separation may contribute to other critical envelope functions, including interphase repair 8 – 13 and chromatin organization 14 – 17 . Following cell division, phase separation of the transmembrane adaptor LEM2 ensures that the ESCRT machinery remodels microtubules and seals the nuclear envelope.

In this paper, the effect of the contact forces of the combined sealing ring by the pre-compressibility of the O-ring seal and the working pressure is studied. The influence of the structural parameters (width, thickness and chamfer) of the friction ring on the contact forces of the combined sealing ring is analyzed. The results show that, in the combined seal, it is not that the higher the pre-compressibility, the higher the sealing efficiency. Under certain working conditions, the chamfer of the friction ring increases, the contact forces of the friction ring decreases; the thickness of the friction ring increases, the contact forces of the friction ring is almost unchanged; The contact force increases with the increase of the width of the friction ring. Under the condition of a given medium pressure of 25 MPa and a compressibility of 22.5%, the optimal values of friction rings L, R, and H and three contact forces and contact forces F under the corresponding conditions are calculated by the optimization algorithm.

Gas emission and diffusion through polymeric materials play crucial roles in ensuring safety and monitoring gas concentrations in technology and industry. Especially, the gas permeation characteristics for O-ring material should be investigated for sealing application in a hydrogen infrastructure. To accommodate the requirements of different environments, we first developed four complementary effective methods for measuring the gas absorption uptake from polymers enriched by pure gas under high pressure and determining the gas diffusivity. The methods included the gravimetric method, the volumetric method, the manometric method, and gas chromatography, which are based on mass, volume, pressure, and volume measurements, respectively. The representative investigated results of the developed methods, such as gas uptake, solubility, and diffusivity are demonstrated. The measuring principles, measuring procedures, measured results, and the characteristics of the methods are compared. Finally, the developed methods can be utilized for testing transport properties, such as the leakage and sealing ability, of rubber and O-ring material under high pressure for hydrogen fueling stations and gas industry.

Hydraulic systems are widely used in engineering fields, where seal reliability is critical to system performance and safety. Addressing potential micro-leakage issues in O-ring seals within high-pressure conditions of hydraulic systems for hydro turbine governors, this study constructs a leakage prediction model for sealing interfaces based on micro-seepage theory. Combined with finite element simulation, it analyzes the sealing process. Simulation results indicate that increasing the O-ring compression ratio significantly enhances both the peak contact stress and the proportion of contact area at the sealing interface, thereby reducing the probability of microscopic pore connectivity. When contact stress falls below a critical threshold, through-flow pathways are likely to form at the interface, causing a sharp increase in leakage probability. Conversely, once contact stress exceeds this critical pressure, leakage probability rapidly decreases toward zero, achieving reliable sealing. This research provides a micro-seepage theory-based reference for sealing design in hydraulic systems, enabling prediction of sealing performance and guiding the selection and compression design of sealing components such as O-rings.