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Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION 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.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION 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.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION 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.)

Lip seals are components subjected to high mechanical stress and they are responsible for many out-of-service in pneumatic cylinders. The aim of this work is the development of an experimental methodology to evaluate lifetime duration and analyse failures and damages of rod lip seals for pneumatic cylinders. A dedicated test bench was designed and manufactured which reproduces actual working conditions of the seals i.e., compressed air action (seal pressurisation) and relative linear reciprocating motion. Three types of seals made of two elastomers (NBR and polyurethane) were tested; dry condition was considered to speed up the tests. The influence of geometric parameters like seal seat dimension and seal axis misalignment with respect to the rod axis, was analysed by multiple experimental tests. Results in terms of seal life duration and failure modes are presented which allow comparison of seals performance and provide a helpful tool to end-users in a proper selection of seals geometry, material and key working parameters. [ABSTRACT FROM AUTHOR]

This article presents the results of a study of oil lip seals with a modified outer lip layer texture. In the first step, the interaction of flat rubber samples with different surface layer textures with the steel surface was recognised. Measurements of the friction coefficient of flat samples with different surface layer textures were carried out. The next step was an experimental study of rotating shaft lip seals in standard and prototype versions. The contact width of the sealing lip before and after durability tests was examined, and the clamping force of the lip on the shaft before and after durability tests was measured. The final step was to create a FEM model of the interaction of the sealing ring lip with the shaft to determine the lip seal pressure and width. These calculations, in cooperation with the previously determined friction coefficient and porosity of the lip seal, allowed the calculation of the friction torque. The solution proposed in this article was intended to be simple and viable for industrial applications. Satisfactory results were achieved with prototype rings in terms of reduced resistance to movement, tightness, and durability. [ABSTRACT FROM AUTHOR]

A stochastic model of the wear process of a shaft lip seal that takes into account random changes in the temperature and external load is described. The results of a numerical analysis of the process of seal wear in relation to the conditions of operation in open space at near-Earth orbital stations are presented. The importance of taking into account random changes in temperature and external load for predicting the seal durability is evaluated. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power 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.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION 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.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION 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.)

Aiming at the shortcomings of traditional lip seal, such as low temperature resistance, poor wear resistance, high friction heat generation and short service life, a method of replacing the traditional lip oil seal with inclined self-compensating oil seal was proposed, and the thermal-structural coupling analysis of oil seal was carried out by using numerical analysis software, to explore the influence law of friction temperature on thermal stress of oil seal. Firstly, the dynamic model of the inclined self-compensating oil seal was established by using the numerical analysis software. The thermal structural coupling analysis method was used to solve the temperature field of the oil seal. Then the temperature field was solved for the oil seal stress, so as to compared and analyzed the difference between the temperature field of the lip seal and the inclined self-compensating oil seal under the same working condition. Finally, a high-pressure and high-speed sealing test-bed was built, and the new technologies such as PT100 temperature sensor and transient liquid crystal measurement were used to measure the sealing point-surface temperature. The experimental study on the temperature rise characteristics of inclined self-compensating oil seal was carried out. The experimental results indicate that the friction temperature rise of the bevel self-compensating oil seal is lower than that of the lip seal. The high friction heat generation of the lip seal and the high elasticity of the material cause the thermal stress concentration of the lip seal and affect the service life of the lip seal. Under the same working condition, the friction temperature rise of the inclined self-compensation seal is lower than that of the lip seal. For every 1 000 r/min increase in rotor speed, the temperature of the lip seal rises by an average of 16.9%, and the temperature of the inclined self-compensation seal increases by an average of 14.1%. When the rotor speed is 3 000 r/min～4 000 r/min, the temperature of inclined self-compensation seal is 21.1%～26.3% lower than that of the lip seal. The results indicate that, under the same working condition, the temperature rise of inclined self-compensating oil seal is lower than that of the lip seal. The low friction temperature rise of slope self-compensation oil seal is instructive for improving the life of the seal. [ABSTRACT FROM AUTHOR]

Deep-sea pressure vessels are specialized pressure vessels designed for automatic deployment from underwater to the surface. These vessels find extensive applications in underwater life-saving and transportation. Their interiors are furnished with a pair of sealing rings, one of which is lip-shaped, and the other is a convex shape, to ensure a dependable seal. With increasing water depth, the sealing rings experience augmented pressure, resulting in a gradual pressing of the rings into the sealing groove. Using ANSYS workbench finite element software, a two-dimensional axisymmetric lip seal finite element model using forces for overall constraint was established, the complete process of progressive pressing into the sealing groove was simulated, and the deformation, contact stress, maximum shear stress, and von Mises stress distribution was also simulated. We also conducted a comparative analysis of lip seals under low and high-water pressure sealing conditions. The findings of the study indicate that when subjected to a combined effect of the installation pre-tightening force and the working water pressure, the lip seal experiences complete compression into the sealing groove at a specific water depth. When subjected to the simultaneous influence of water pressure on the sealing ring material and friction force on the contact surface, two extremes of contact stress manifest in the primary sealing zone of the lip seal. These extremes have the capacity to elevate the contact stress and the effective sealing width, ultimately leading to an improvement in the sealing performance. Concurrently, as the water pressure gradually increases, the inner concave circle of the sealing ring experiences stretching, leading to a reduction in stress concentration, equivalent stress, and shear stress to a considerable extent. This mechanism ensures that the lip-shaped sealing ring retains sufficient strength. This study offers a viable solution for conducting sealing studies on deep-sea separable pressure vessels. [ABSTRACT FROM AUTHOR]

Lip seals are components subjected to high mechanical stress and they are responsible for many out-of-service in pneumatic cylinders. The aim of this work is the development of an experimental methodology to evaluate lifetime duration and analyse failures and damages of rod lip seals for pneumatic cylinders. A dedicated test bench was designed and manufactured which reproduces actual working conditions of the seals i.e., compressed air action (seal pressurisation) and relative linear reciprocating motion. Three types of seals made of two elastomers (NBR and polyurethane) were tested; dry condition was considered to speed up the tests. The influence of geometric parameters like seal seat dimension and seal axis misalignment with respect to the rod axis, was analysed by multiple experimental tests. Results in terms of seal life duration and failure modes are presented which allow comparison of seals performance and provide a helpful tool to end-users in a proper selection of seals geometry, material and key working parameters.

This article presents the results of a study of oil lip seals with a modified outer lip layer texture. In the first step, the interaction of flat rubber samples with different surface layer textures with the steel surface was recognised. Measurements of the friction coefficient of flat samples with different surface layer textures were carried out. The next step was an experimental study of rotating shaft lip seals in standard and prototype versions. The contact width of the sealing lip before and after durability tests was examined, and the clamping force of the lip on the shaft before and after durability tests was measured. The final step was to create a FEM model of the interaction of the sealing ring lip with the shaft to determine the lip seal pressure and width. These calculations, in cooperation with the previously determined friction coefficient and porosity of the lip seal, allowed the calculation of the friction torque. The solution proposed in this article was intended to be simple and viable for industrial applications. Satisfactory results were achieved with prototype rings in terms of reduced resistance to movement, tightness, and durability.

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION 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.)

Marine thruster lip seals pose a condition monitoring challenge, yet they are seldom studied tribologically. The present work studies the behavior of a 300 mm diameter NBR marine thruster lip seal (n = 3) under typical operating conditions. Frictional torque and subsurface temperature were measured under 27 combinations of oil temperature, oil pressure, and rotational speed. The frictional torque increased with increasing oil pressure and decreased with increasing oil temperature. The subsurface temperature increased with increasing oil temperature, oil pressure, and rotational speed. There was no clear relation between the frictional torque and subsurface temperature. The frictional torque ranged 9.6–14.4 Nm, and subsurface temperature 57–94 °C. Preliminary wear measurements showed a wear track width of 0.2–0.3 mm and a wear rate of 0.031 ± 0.001 mm3/hour. • 300 mm diameter marine lip seal (n = 3) studied under 27 operating conditions. • Frictional torque ranged 9.6–14.4 Nm and subsurface temperature ranged 57–97 °C. • Average wear rate was 0.031 ± 0.001 mm3/hour. [ABSTRACT FROM AUTHOR]

Deep-sea pressure vessels are specialized pressure vessels designed for automatic deployment from underwater to the surface. These vessels find extensive applications in underwater life-saving and transportation. Their interiors are furnished with a pair of sealing rings, one of which is lip-shaped, and the other is a convex shape, to ensure a dependable seal. With increasing water depth, the sealing rings experience augmented pressure, resulting in a gradual pressing of the rings into the sealing groove. Using ANSYS workbench finite element software, a two-dimensional axisymmetric lip seal finite element model using forces for overall constraint was established, the complete process of progressive pressing into the sealing groove was simulated, and the deformation, contact stress, maximum shear stress, and von Mises stress distribution was also simulated. We also conducted a comparative analysis of lip seals under low and high-water pressure sealing conditions. The findings of the study indicate that when subjected to a combined effect of the installation pre-tightening force and the working water pressure, the lip seal experiences complete compression into the sealing groove at a specific water depth. When subjected to the simultaneous influence of water pressure on the sealing ring material and friction force on the contact surface, two extremes of contact stress manifest in the primary sealing zone of the lip seal. These extremes have the capacity to elevate the contact stress and the effective sealing width, ultimately leading to an improvement in the sealing performance. Concurrently, as the water pressure gradually increases, the inner concave circle of the sealing ring experiences stretching, leading to a reduction in stress concentration, equivalent stress, and shear stress to a considerable extent. This mechanism ensures that the lip-shaped sealing ring retains sufficient strength. This study offers a viable solution for conducting sealing studies on deep-sea separable pressure vessels.

In the present study of eight cases of traumatic lower lip defects, the reconstruction was achieved in a single stage by V-Y advancement island chin myocutaneous flap and labial mucosal advancement flap. There are many methods described for the reconstruction of small-to-large size of lower lip defects from straight-line closure of small defects to local flaps and free flaps for large defects. V-Y advanced chin flap has been reported previously also for the repair of lower lip defect with varying results. The vermilion reconstruction in others reported cases was done with the free mucosal grafts, V-Y labial mucosa advancement, or pedicled tongue flaps. Tongue flap is a two-stage procedure with esthetically unnatural look and an irregular surface of the vermilion. The free mucosa graft showed necrosis partial or complete resulting in irregular surface of vermilion and notching in the lip. V-Y labial mucosa advancement was done more for a small defect of the lip only. In the present series, we have repaired the vermilion of the lip by labial mucosal advancement flap, muscle by advancement of orbicularis oris from chin flap, and skin by V-Y advancement of island myocutaneous chin flap. Our results showed normal oral size with no evidence of microstoma or commissural distortion; oral competence was good with normal sphincteric function. The vermilion reconstructed had normal color and sensation. Lip seal was very good without notching defect in the vermilion. Drooling of saliva or speech defect was not noticed. The facial expressions and the look of the face were near normal. Hence, esthetically and functionally, the results were good without any irregularity or notching of the lip along with no incidence of drooling of saliva. We think that this technique may be considered as a procedure of choice for managing the moderate-to-large post traumatic defects of the lower lip. It is good esthetically and functionally besides being single stage for reconstructing moderate-to-large defects of the lower lip and is satisfying to the patient. [ABSTRACT FROM AUTHOR]

The paper presents the results of research into a hybrid seal which is a combination of standard rotary lip seals and a magnetic fluid seal. To maintain the magnetic fluid in the friction zone region, either a specially shaped pole piece was used or the shaft was modified accordingly. The research study concerns the allowable operating pressure and lubrication conditions in short-term and durability tests after which shaft wear was also assessed. Magnetic fluids with different rheological and magnetic properties were considered. The test results showed that the long-term operation of a hybrid seal is possible. The requirements, however, are the appropriate value of the magnetic field and dynamic viscosity of the magnetic fluid. [ABSTRACT FROM AUTHOR]

In slow-moving compressor stages the piston-cylinder seal is one of the most critical components affecting the tightness of the working chamber. In the present work, conditional clearances in the lip seal of low-speed compressor stages are determined by the method of static blowing. A comparative assessment of the leak-tightness of the piston-cylinder seal with a different number of cuffs and different wall temperatures is carried out

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION 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 paper presents theoretical studies to increase the service life of piston seals made on the basis of fluoroplastic by changing the speed of movement of the piston and, accordingly, a more efficient cooling mode. A design with two oppositely moving pistons is proposed, which allows to increase the service life of low-speed long stroke stages

Oral competence refers to the maintenance of lip closure with sufficient strength to prevent anterior spillage of saliva, food and fluid, and to clearly articulate labial sounds. Despite facial nerve paralysis having an impact on eating, drinking and communicating, little research has been done in this area. Studies examining oral competence associated with a diagnosis of facial nerve paralysis were considered using Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement checklists and evaluated for their risk of bias using the RevMan Risk of Bias Tool. 44 articles were examined. There was an over-representation of case-series and cohort studies. All studies carried a high risk of bias due to lack of (a) validated outcome measures, (b) comparison group and (c) blinding or randomised assessors and participants. Studies primarily examined facial nerve intervention for the purpose of restoring smiling or facial aesthetics rather than oral competence. Whilst oral competence is often compromised after a facial nerve paralysis, it is inconsistently measured, managed and described. Further studies are required to examine the (a) incidence, (b) severity and (c) impact on quality of life relating to oral incompetence using validated measures at consistent time intervals. [ABSTRACT FROM AUTHOR]

No matter the scale, stirred tank bioreactors are the most commonly used systems in biotechnological production processes. Single-use and reusable systems are supplied by several manufacturers. The type, size, and number of impellers used in these systems have a significant influence on the characteristics and designs of bioreactors. Depending on the desired application, classic shaft-driven systems, bearing-mounted drives, or stirring elements that levitate freely in the vessel may be employed. In systems with drive shafts, process hygiene requirements also affect the type of seal used. For sensitive processes with high hygienic requirements, magnetic-driven stirring systems, which have been the focus of much research in recent years, are recommended. This review provides the reader with an overview of the most common agitation and seal types implemented in stirred bioreactor systems, highlights their advantages and disadvantages, and explains their possible fields of application. Special attention is paid to the development of magnetically driven agitators, which are widely used in reusable systems and are also becoming more and more important in their single-use counterparts. Key Points • Basic design of the most frequently used bioreactor type: the stirred tank bioreactor • Differences in most common seal types in stirred systems and fields of application • Comprehensive overview of commercially available bioreactor seal types • Increased use of magnetically driven agitation systems in single-use bioreactors [ABSTRACT FROM AUTHOR]

The pressure between a shaft and a reinforced rubber cuff (a lip seal) is considered. An algorithm is derived for calculating the contact pressure, taking account of the properties of the material, the thickness of the cuff's active section, its inclination to the shaft, the spring's tensile force, and the geometric parameters of the cuff's free section. [ABSTRACT FROM AUTHOR]

A thermomechanical model of a stern tube seal has been developed by paying particular attention to the contact between the seal and the shaft. The finite element method is used to capture the macroscopic behavior of the seal while roughness was evaluated at a microscopic level by applying the boundary element method. The seal material was independently characterized, and the results were used to calibrate the material constitutive model used for the seal. Two specialized setups were built to validate the model in terms of radial force, contact width, and percolation threshold. By combining the two models, the strains, stresses, temperature, and the limits of static tightness can be predicted at high accuracy for a wide range of operating conditions. [ABSTRACT FROM AUTHOR]

This study is devoted to the effect of different coefficients on the calculation results of the rotary lip seal mixed lubrication model. It was proved by experiments that the dry friction coefficient used in the previous models was quite different from the boundary lubrication friction coefficient, which was theoretically more accurate. The pumping rate, friction torque, pressure distribution, and oil film thickness were calculated using both the dry friction coefficient and the boundary lubrication coefficient and the results were quite different. A friction coefficient test method under boundary lubrication condition for numerical simulation of rotary lip seals and an improved method for numerical calculation using the boundary lubrication coefficient instead of the dry friction coefficient were proposed. It was verified that the accuracy of numerical calculation can be improved, and the calculation result was closer to the actual working state. [ABSTRACT FROM AUTHOR]

In this study, a test system is developed in order to determine the effect of interference on the lifetime of the sealing element. A set of experiments are carried out with thermoplastic polyurethane radial lip seals with three different inner diameters varied by lip surface tolerance (40, 39.80 and 39.60 mm), and EP gear oil is used as lubricant. In order to determine the lifecycle of the sealing element, mass of the leaking oil is measured. Meanwhile, in order to determine the frictional performance of the sealing element, four load cells are mounted on the cylindrical housing of the system and frictional force values are monitored by a data acquisition terminal and frictional torque values are calculated. As a result, the frictional moment values of the seals increased with the increase in interference. Moreover, the increase in interference leads to a longer service life. [ABSTRACT FROM AUTHOR]

In literature the lubrication of rotary lip seals is explained by hydrodynamic action on a microscopic scale. This theory assumes perfect concentricity between the seal and the shaft which in reality seldomly occurs. Focusing on the stern tube seals application, an analysis is performed on the phenomena distorting the axisymmetric operation of rotary lip seals. Radial and angular shaft misalignments together with pressure and temperature gradients have been modelled. The model predictions are validated using a dedicated setup. Additionally, applying the soft-EHL film thickness expressions at the asperity level, an equivalent film thickness along the circumferential direction is estimated. The Reynolds PDE is solved to predict the misalignment-induced hydrodynamic pressure build-up. The film thickness variation derived and accompanying non-uniform contact pressure distribution was shown to be sufficient for hydrodynamic action and, depending on the minimum film thickness, the hydrodynamic pressure build-up can exceed the static contact pressure. Additionally, significant differences were observed between the radial and angular misalignment configurations.

The effect of lip surface microtopography on lubrication of radial shaft seals is studied numerically. Numerical analysis of hydrodynamic flow at the lip is conducted with a simple sinusoidal wave as a lip surface asperity model. In order to understand the effects of lip surface microtopography on micro EHL, amplitude, wavelength, curvature and asperity ratio on film formation are investigated. It is found that the wavelength, the curvature and the aspect ratio significantly affect film formation and the coefficient of friction, and that coefficient of friction is influenced not only by minimum film thickness but by the average film thickness.

It is generally agreed that radial lip seals are used in systems with a rotating shaft and a stationary lip. However, according to previous work, it was demonstrated that relative motion between the shaft and the lip has substantial effects on the hydrodynamic lifting load and sealing performances. Nowadays, new generations of textured shafts have emerged in order to reduce friction torque and improve reverse pumping, but no study has confirmed the effect of the relative motion between the rough lip and the shaft grooves on the rotary lip seal performances. In this work, an isothermal hydrodynamic lubrication was performed in transient conditions to investigate the effect of the relative velocity between an oblique grooved shaft and a rough lip. After confirming the validity of the current model with respect to previous works, simulations have underlined the effect of the grooved shaft with relative lip motion on the rotary lip seal performance. Indeed, by keeping the same relative velocity between surfaces, it is shown that moving the shaft with a rate higher than that of the lip surface could produce an important reverse pumping and reduce the friction torque significantly, in comparison with cases where the shaft velocity is weaker.

On the basis of elastohydrodynamic model established by the present authors in advance, the present study numerically analyzes the influence of the axial position of contact zone on the sealing performances of lip seals with different micro-dimple texture shapes (circle, square and triangle) on the shaft surface, assuming a smooth elastomer and that the contact zone spans only a few rows of texture. It is found that the triangle micro-dimple texture shape that can always produce positive pumping rate no matter where the contact zone locates on the shaft surface. According to the determined texture shape, parameter analysis is conducted to select the optimal shape parameter that is less sensitive to the axial position of contact zone and produces more pumping rate and less friction torque. [ABSTRACT FROM AUTHOR]