Rubber O-rings Research Articles

Establishment of experimental models to evaluate the effectiveness of dental trauma splints.

The purpose was to describe a novel simple experimental model of injured teeth for developing dental trauma splints (DTS), and to test various splints by combining use of this model and the Periotest® device. Rubber O-rings and spring washers were used to simulate and modify injured tooth mobility. Splinting effects were assessed among three kinds of DTS, including a composite splint and two wire-composite splints (1: rectangular orthodontic wire 0.533×0.635 mm, 2: cobalt-chromium alloy wire Φ0.9 mm). The Periotest values were measured three times for each tooth before and after splint insertion. The splinting effect was defined as the change in tooth mobility. Splinting effects significantly increased in the order wire-composite splint 1<wire-composite splint 2<composite splint (p<0.05). This model system could evaluate the effects of DTS including the differences among various splint methods, which showed reasonable reproducibility of dental trauma situations depending on severity in clinical usage.

Dynamic Characterization of Rubber O-Rings: Squeeze and Size Effects

This paper concerns the dynamic characterization of rubber O-rings used to introduce damping in high speed gas bearing systems. O-shaped rubber rings composed of high temperature rubber compounds are characterized in terms of stiffness and damping coefficients in the frequency range 100–800 Hz. Simple formulas with frequency independent coefficients were identified to express the viscoelastic properties of the O-rings. The formulas proposed approximate the stiffness and damping coefficients of O-rings of general size.

Use of pyrolyzed paper as disposable substrates for voltammetric determination of trace metals

The possibility of using pyrolyzed paper as disposable working electrodes for trace metals determination is reported for the first time. A small piece of pyrolyzed paper (0.7×0.7cm) was positioned at the bottom side of the electrochemical cell using a rubber O-ring, which defined the electrode area (0.48cm; 0.18cm2). A large number of electrodes can be obtained from a single piece of standard dimensions (2.5cm×7.5cm) of paper, therefore minimizing the cost per unit. The electrochemical performance of the pyrolyzed paper was demonstrated by cyclic voltammetry, electrochemical impedance spectroscopy and by the determination of Zn, Cd, and Pb by square-wave anodic stripping voltammetry. The unmodified pyrolyzed paper showed excellent performance for Pb and Cd detection (LOD =0.19 and 0.16 ppb, respectively). In the presence of Bi3+(in-situ film formation), the simultaneous determination of Zn, Cd and Pb was also possible (LOD=0.26, 0.25, and 0.39 ppb, respectively).

Electroless Pd deposition on a planar porous stainless steel substrate using newly developed plating rig and agitating water bath

A new plating bath was developed to prevent palladium plating in the pores of the porous stainless steel support when using plate-type porous substrate. The plating bath, composed of a holder, a rubber O-ring and a bottom, provides very simple assembly and is very effective in preventing palladium plating in the pores of porous stainless steel. The agitation of the plating solution increases plating rate significantly because the agitation improves the external mass transfer of Pd ion and reducing agent to the membrane surface facilitating ~99.7% plating yield of palladium ion. This new plating method carried out at a temperature range of 293 to 298 K provides a very simple and economic membrane manufacturing process. Using a newly developed plating rig, an 88.9-mm diameter membrane was fabricated, and gas permeation tests showed that the hydrogen permeation flux reached ~0.9 mol s−1 m−2 at 873 K and a pressure difference of 300 kPa and selectivity (H2/N2) was ~1,850 at 873 K with a pressure difference of 100 kPa.

기만기 적용 고무 O-ring의 온도에 따른 가속수명시험을 통한 수명예측에 관한 연구

기만기 적용 고무 O-ring의 온도에 따른 가속수명시험을 통한 수명예측에 관한 연구

Corrosion mechanism of hydrogenated nitrile butadiene rubber O-ring under simulated wellbore conditions

Corrosion testing of hydrogenated nitrile butadiene rubber (HNBR) O-ring was conducted at 140°C, 35MPa containing 0.5MPa CO2 for 168h in simulated wellbore conditions using self-designed compression simulator and autoclave. The mechanical properties, EDS and fracture morphology analyses were performed. The corrosion under the compression state was more serious than that under the free state. Moreover, liquid corrosion was more serious under the free state. The decrease of mechanical properties can be attributed to the penetration of corrosive media and chemical actions, which changed the structure of rubber chains, weakened the reinforcement role of carbon black (CB).

Clinical and radiographic evaluation of implant-supported removable partial overdenture in the lower Kennedy class IV cases

Introduction The objective of the present study was to evaluate the effect of implant-supported partial overdenture design in restoring mandibular long class IV Kennedy's classification on the supporting structure, both clinically and radiographically. Materials and methods Ten partially edentulous patients with lower six anterior teeth missing were selected. Their ages ranged from 40 to 50 years. Each patient received two dental implants placed in the lower edentulous span at the canine area bilaterally. Ball-and-socket attachment (polycarbonate housing with rubber O-ring) was used between the implant and the overlay removable partial denture for retention. Periodic evaluation was carried out for every patient before denture insertion and then after 3, 6, and 9 months. As regards the clinical evaluation, the probing depth, gingival level, and attachment level around the implants were recorded. The radiographic evaluation included the use of specially developed software for measuring the alveolar bone density in gray scales and the bone height in pixels for the implants and the residual alveolar ridges. Results All implants were highly successfully osseointegrated at the end of this study. There was a statistically nonsignificant increase in the clinical parameters (probing depth, gingival level, and attachment level) around the dental implants throughout the 9-month follow-up period after denture insertion. Radiographically, there was a nonsignificant increase in bone loss, but a significant increase in bone density around the dental implants and the alveolar ridge throughout the follow-up period. Conclusion From the previous results, it was found that the concept of immediate loaded dental implant was efficient to be used successfully in the mandibular long Kennedy class IV to retain the partial overdenture.

福島第一原子力発電所事故の考証

Many lessons can be learned from the Fukushima Daiichi Nuclear Power Plant (NPP) accident. After the loss of Emergency Core Cooling System (ECCS) and IC core cooling, fuels in the core melted down. Leak of fission product and hydrogen began because of high-temperature damage to the PCV packing. A hydrogen explosion occurred in the upper floor in the reactor building in Units 1, 3 and 4. At Unit 2, reactor core isolation cooling (RCIC) continued to function for about 3 days. Soon after the loss of RCIC water injection, the water level in the RPV declined. Drywell pressure increased from 400 kPa to 750 kPa, and PCV top flange might leak began through silicon rubber O-ring. It was an initiation of severe contamination around the NPS. In the afternoon on March 15, wind blew toward Iidate village. Melted core relocation into lower plenum caused the radiation level increased. The radiation level was measured by containment atmospheric monitoring system (CAMS).

Fatigue life and fracture mechanics of unconstrained Ni–Mn–Ga single crystals in a rotating magnetic field

Fracture resistance and long fatigue life are required to commercialize Ni–Mn–Ga ferromagnetic shape memory alloys. While Ni–Mn–Ga achieves high fatigue life at low strains, there is little data on the fatigue life of samples that are actuated near the theoretical strain limit. Furthermore, constraints imposed by clamping samples impact their magneto-mechanical and fatigue properties. Here, 10M Ni–Mn–Ga single crystals were exposed to a rotating magnetic field while holding them with rubber O-rings so they were minimally constrained. Prior to testing, sample surfaces were prepared to various levels of finish. Fatigue life varied with some samples reaching more than 800,000 cyclic loads before fracturing and some samples failing after only 4000 cyclic loads. Long fatigue life and fracture resistance are achieved when avoiding crystal defects and surface imperfections. Short fatigue life was caused by high surface roughness and stress concentration at defects and notches.

Enhancement of seal life through carbon composite back-up rings under shock loading conditions in defence applications

The life of Nitrile Butadiene Rubber (NBR) O-ring seal having shore hardness of A70 and A90 under shock loading conditions was investigated by a specially designed pneumo-hydraulic shock test rig. Shock tests have been carried out on bare seals, seal with conventional polytetrafluoroethylene (PTFE) back-up rings and seal with newly developed carbon composite back-up rings to study its behaviour under different operating conditions until failure. Experiments were conducted by varying annular gap ranging from 0.3 to 0.5 mm, oil temperature from 30 °C to 70 °C and rate of pressure rise from 600 to 2400 MPa/s. Significant enhancement in seal life was observed with carbon composite back-up ring at reduced annular clearances compared to seal life with conventional PTFE back-up ring and without back-up rings.

Sensor integration in rubber gaskets for structural health monitoring made by compression molding

This research work shows the integration process and characterization of a miniaturized strain gauge sensor in rubber O-rings for structural health monitoring (SHM). Strain gauges have been successfully embedded during compression molding, which is a commonly used fabrication method of rubber components. The sensor signal is correlated with the contact pressure of the gasket that abates over time due to aging processes. This can be exploited for lifetime prediction. Embedding sensors into rubber applying compression molding is a novel method that allows the integration into non-liquid elastomers. The strain gauge resistance correlates linearly to the contact pressure. An artificial aging test exhibits an exponential decrease in the resistance caused by the relaxation processes during the accelerated aging of the elastomer at 70 °C for 72 h. Uniaxial tensile testing with dumbbell specimens reveals the influence of the integrated sensors. It is demonstrated that the influence heavily depends on the sensor size.

Development of Herringbon-Grooved Aerodynamic Journal Bearing Systems for Ultra-High-Speed Rotations

It is absolutely important for ultra-compact rotational machineries to achieve sable shaft rotation at ultra-high-speed. This paper discussed herringbone-grooved aerodynamic journal bearing systems developed for the purpose. In this system, the bearings are supported by rubber-O-rings for accurate and stable operations. To grasp the possibility for stabilization, two types of O-rings with different stiffness and damping properties under bearing supporting were tested in the experiment. As the results, the bearing system demonstrated the maximum rotational speed over 460,000 rpm without unstable phenomenon called whirl. However, the difference in rubber O-rings definitely affected the stability of the bearing system.

Attenuation of short stress pulses in strongly nonlinear dissipative metamaterial

Attenuation of short stress pulses under different levels of precompression was investigated in a one-dimensional strongly nonlinear discrete metamaterial assembled using alternating steel disks and toroidal Nitrile O-rings. The results were compared with the numerical modeling. A double power-law is used to describe the nonlinear interaction between the disks due to the compression of rubber O-rings. The dispersion behavior caused by the periodic arrangement of elements is contributing to the attenuation of pulse, but could not explain the experimental observations. It was explained by taking into account the nonlinear viscous behavior of O-rings. The numerical simulations were able to predict the dependence of the signal speed on the precompression force, a significant decrease of the pulse width with the precompression and the attenuation of the leading positive pulse, the latter of major significance in the protection against impact. This strongly nonlinear dissipative metamaterial has a potential for attenuation of dynamic loading and allows an enhanced tunability of signal speed and degree of attenuation.

901 電力施設用ゴムOリングの圧縮永久ひずみと反力のFEM解析(OS9 オーガナイズドセッション≪発電機器の材料・構造解析と評価≫)

In this paper, leakage tests of rubber O-ring were conducted using original jig to evaluate relationship between restoring force and leakage of rubber O-ring. The relationships between restoring force and leakage of rubber O-ring were measured by original jig. Sealing performance of rubber O-ring decreased significantly when restoring force of compressed rubber O-ring was less than 271 N. In addition, compression set of rubber O-ring was estimated using a 3-dimentinal FEM simulation code. The FEM simulation code is based on a nonlinear viscoelastic model of rubber which reproduce stress relaxation depending on temperature. From the test results and FEM simulations, compression set of rubber O-ring was investigated.

058 密封気体の圧力が電力施設用ゴムOリングのシール性能に及ぼす影響

058 密封気体の圧力が電力施設用ゴムOリングのシール性能に及ぼす影響

Stress distribution patterns of implant supported overdentures-analog versus finite element analysis: A comparative in-vitro study.

Aims and Objectives:The aim of this study was to asses & compare the load transfer characteristics of Ball/O-ring and Bar/Clip attachment systems in implant supported overdentures using analog and finite element analysis models.Methodology:For the analog part of the study, castable bar was used for the bar and clip attachment and a metallic housing with a rubber O-ring component was used for the ball/O-ring attachment. The stress on the implant surface was measured using the strain-gauge technique. For the finite element analysis, the model were fabricated and load applications were done in a similar manner as in analog study.Results:The difference between both the attachment systems was found to be statistically significant (P<0.001).Conclusion:Ball/O-ring attachment system transmitted lesser amount of stresses to the implants on the non-loading side, as compared to the Bar-Clip attachment system. When overall stress distribution is compared, the Bar-Clip attachment seems to perform better than the Ball/O-ring attachment, because the force was distributed better.

Note: O-ring stack system for electron gun alignment.

We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignment and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications.

Fretting Characteristics of Fluorine Rubber O-ring for Reciprocating Shaft Seal

Fretting Characteristics of Fluorine Rubber O-ring for Reciprocating Shaft Seal

Fracture Model Analysis of Rubber O-Ring Influenced by High-Pressure Hydrogen Gas

Fracture Model Analysis of Rubber O-Ring Influenced by High-Pressure Hydrogen Gas

Durability and field condition study of seal of SAVY-4000 storage container

The conditions of use for rubber O-rings are at least as important as their physical properties in their effect on the quality of a seal. Under normal use conditions, O-rings may be subject to wear and environmental contaminants such as hair and dirt. This study examines how these factors impact the leak tightness of a nuclear material storage container and the likelihood of the inadvertent release of radioactive material. The durability lifetime of an O-ring was explored by opening and closing four SAVY-4000 1 quart containers 100 times and periodically performing helium leak testing, though no significant change in leak rate was observed. This study also explored how the accumulation of dust or hair on the O-ring surface would affect the leak rate of the containers. A single hair crossing the seal, or a sufficient amount of particulate matter would compromise the seal, but after cleaning, the seal was re-established.