Academic literature on the topic 'Rubber Grommet'

A grommet, made of ethylene propylene diene methylene (EPDM) rubber, is an integral part used for fixing and protecting the wire inserted from the outside to the inside of vehicles. Rubber compounds exhibit various mechanical properties and vulcanization characteristics depending on the accelerator mixing ratio. These mechanical properties affect the insertion and detachment forces when the grommet is manufactured and fixed to the vehicle body. In this study, we experimentally analyzed the changes in the properties of EPDM rubber depending on the vulcanization accelerator to improve the mounting performance of the grommet, and subsequently derived the optimum accelerator mixing ratio. We implemented a mixture design strategy to derive the optimum mixing ratio for obtaining the desired mechanical properties and vulcanization characteristics. The insertion and separation forces of the existing grommet were compared with those of the grommet fabricated using the derived mixing ratio and we found that the mounting performance was improved compared to the existing grommet.

The first recorded myringotomy was in 1649. Astley Cooper presented two papers to the Royal Society in 1801, based on his observation that myringotomy could improve hearing. Widespread inappropriate use of the procedure followed, with no benefit to patients; this led to it falling from favour for many decades. Hermann Schwartze reintroduced myringotomy later in the nineteenth century. It had been realised earlier that the tympanic membrane heals spontaneously, and much experimentation took place in attempting to keep the perforation open. The first described grommet was made of gold foil. Other materials were tried, including Politzer's attempts with rubber. Armstrong's vinyl tube effectively reintroduced grommets into current practice last century. There have been many eponymous variants, but the underlying principle of creating a perforation and maintaining it with a ventilation tube has remained unchanged. Recent studies have cast doubt over the long-term benefits of grommet insertion; is this the end of the third era?

The first recorded myringotomy was in 1649. Astley Cooper presented 2 papers to the Royal Society in 1801, based on his observations that myringotomy could improve hearing. Widespread inappropriate use of the procedure followed, with no benefit to patients; this led to it falling from favor for many decades. Hermann Schwartze reintroduced myringotomy later in the 19th century. It had been realized earlier that the tympanic membrane heals spontaneously, and much experimentation took place in attempting to keep the perforation open. The first described grommet was made of gold foil. Other materials were tried, including Politzer’s attempts with rubber. Armstrong’s vinyl tube effectively reintroduced grommets into current practice last century. There have been many eponymous variants, but the underlying principle of creating a perforation and maintaining it with a ventilation tube has remained unchanged. Recent studies have cast doubt over the long-term benefits of grommet insertion; is this the end of the third era?

A grommet is a representative component that fixes the position of a cable. It is made from hyper-elastic materials (rubber), such as ethylene propylene diene monomer (EPDM). The grommet and cable are conventionally fixed through bonding; however, this method has numerous disadvantages that can be improved through relevant research. To apply a fixing method using the elastic force of EPDM rubber, this paper presents an empirical equation for approximating the bonding force of EPDM grommet parts with a hollow shaft geometry. First, tensile tests and the inverse method were used to approximate the basic mechanical properties. The physical properties were derived through basic tests; furthermore, bonding force tests and the inverse method were used on a grommet with a hollow shaft structure. In addition, the Box–Behnken design of experiments was used to predict the amount of change in the bonding force according to the geometry variables. Finally, this study was validated by comparing the approximation results derived through the design of experiments with the analysis and bonding force test results.

Ethylene propylene diene monomer (EPDM) has superior mechanical properties, water resistance, heat resistance, and ozone resistance. It can be applied to various products owing to its low hardness and high slip resistance properties. A grommet is one of the various products made using EPDM rubber. It is a main component of automobiles, in which it protects wires throughout the inside and outside of a vehicle body. The grommet, made of EPDM, has different mounting performance depending on the process parameters and the shape of the grommet. This study conducted optimization to improve the mounting performance of a grommet using EPDM materials. The physical properties of the main molding materials were investigated according to process parameters. A grommet was fabricated according to the process parameters of fabrication. Insertion force and separation force were examined through experiments. Nonlinear material constants were determined through uniaxial and biaxial tensile tests. The nonlinear analysis of the grommet was conducted, and a compound design that incorporated the shape parameters for the minimum load of each part was derived. Then, additional nonlinear analysis was performed. This was followed by a comparative analysis of the actual model through experimental evaluation.

Deflashing is the process of removal of excess flashes from the rubber products. Initially deflashing was a manual operation where dozen of workers, seated at small work stations would take each part and trim the excess rubber off with scissors, knives or by grinding. Still the same method is employed in most of the rubber industry. The drawbacks of this method are demand inconsistent and repeatable quality. Work done by hand is often inconsistent. There are commercially available cryogenic deflashing machine but they are too expensive hence cost effectiveness is also a prime factor. The objective of this paper is to develop a technique, to identify the media through which the flashes can be removed easily and effectively. Based on the test results obtained from testing of five different types of media, ABCUT Steel media gave best results. The testing of the ABCUT Steel media on rubber samples like O-rings, grommet tail door, bottom bush etc. shows good results.

Residential air conditioning units include several sources which can lead to vibrational and noise issues. The most important structure-borne source is the compressor which controls the noise and vibration in certain frequency ranges. Compressors are mounted on four relatively stiff rubber grommets which partially isolate the basepan from the compressor motion while also ensuring that the compressor does not move too much. In this work, the grommets are simulated using the finite element method and results are correlated with measurement results with good agreement. It is demonstrated that the hyperelastic properties of the grommets should be increased due to the Payne effect to improve correlation.

This paper presents an accelerated life test for embrittlement of natural rubber grommets. From the analyses of field samples, it is found that embrittlement is due to the decrease of plasticizer (zinc stearate for natural rubber) in the rubber. To estimate the embrittlement life, an accelerated life test is designed based on a factorial design. Temperature and compression load are selected as accelerating variables, and the hardness is measured for each specimen during the test. An analysis of variance indicates that the significant factor affecting the hardness is not load, but temperature. The embrittlement life and temperature relationship and the acceleration factor are estimated from the failure times using linear degradation model under the assumptions of Weibull lifetime distribution and Arrhenius model.

SUMMARYThe bacteriological investigation of an outbreak of Legionnaires' disease in Glasgow Royal Infirmary affecting 16 patients is described. Most of the patients had been treated in high-dependency areas on two floors of the hospital supplied by the same two air-conditioned ventilation systems. The source of infection was traced to contamination of a cooling tower from which a plume of spray discharged into the intake vents of the two ventilation systems. Rubber grommets within the cooling tower probably provided a nidus of infection there. The control and management of the outbreak are discussed: a policy of frankness about the course and progress of the investigations was adopted and helped to allay anxiety on the part of both staff and media.

AbstractThe middle ear cavity is exposed and vulnerable to waterborne infection in patients with grommets, perforated tympanic membranes and after radical mastoidectomy. Patients suffering from chronic otitis externa and those receiving radiotherapy to the head and neck also have an increased susceptibility to such infections. Many advocate the use of waterproof ear protectors in such patients when swimming. The choice of a suitable ear protector is complicated as many are now available commercially.This study was therefore designed to evaluate the degree of protection afforded by seven different ear protectors in a group of six swimmers. A very sensitive, original method of water detection was devised incorporating a pH indicator strip.The results showed conclusively that cotton wool coated in paraffin jelly BPC was the most effective method of ear protection and was found to be comfortable and easy to use. Other methods, including custom-made silicone rubber plugs, were not adequate in sealing the external auditory canal and are considerably more expensive.

The tractor is the machines that provides the largest percentage of power used on rural activities inside the agricultural automation, making the researches on parameters of the vibration frequency on the rubber grommet and the tridimensional magnitude more convenient, in order to contribute to the future engineering researches. Therefore, this work has the main objective to analyze the magnitude of efficient accelerations on the seat-operator interface and the vibrations transmissibility of the rubber grommet on the agricultural tractor with a cabin, using three adjustment knob positions, two scarification depths, two displacement speeds and three different ballast settings. The experiment was held at the Phytotechny School s experimental area (Federal University of Santa Maria) through a subdivided portion outlining with 4 repetitions and 144 experimental units. A 4x2 TDA tractor was used with 63 kW of power on the engine (63 kW) attached to the chisel plow. The information was recorded by the accelerometers that were installed on the floor of the cabin, platform, rubber grommet and on the seat. It was concluded that the magnitude of efficient accelerations obtained on the seat-operator interface in all the 36 individual tests stayed above the comfort limit on the frequency of 1 to 80Hz, established by the standard (ISO 2631-1: 1997) for daily 8-hour exposure. The magnitude of efficient accelerations on the vertical direction (z) in the tractor s cabin floor in all the 36 individual tests had comfortable rates for the total metallic ballasting (TMB) and little uncomfortable for both the partial metallic ballasting (PMB) and the total hydraulic ballasting (THB) according to the (ISO 2631-1: 1997). The vibration transmissibility, on the direction (z) through the rubber grommet, had an amplification in the interval from 0 to 15Hz for TMB, from 0 to 19Hz for PMB and from 71 to 76Hz for THB. The transmissibility rates in the analysis between 1 and 80 Hz corresponded to 59%, 74% and 88% for TMB, PMB and THB, respectively. In all the individual tests, the vibration transmissibility from the floor to the seat was around twenty times higher compared to the vibration transmissibility from the platform to the tractor floor, using the frequency range from 1 to 80 Hz. On the virtual dynamic simulation, the elastomer provided around 11% reduction for the vibration magnitude on the seat-operator interface in the vertical direction.
O trator é uma das máquinas que fornece a maior parte da potência para execução das atividades rurais dentro da mecanização agrícola, sendo oportunas maiores investigações dos parâmetros de frequência da vibração nos coxins e magnitudes tridimensionais no assento, a fim de contribuir para futuras pesquisas de engenharia. Sendo assim, este trabalho teve por objetivo analisar as magnitudes das acelerações eficazes na interface assento-operador e a transmissibilidade das vibrações no coxim de um trator agrícola cabinado, utilizando três posições de regulagem do assento, duas profundidades de escarificação, duas velocidades de deslocamento e três configurações de lastros. O experimento foi realizado na Universidade Federal de Santa Maria com delineamento de parcelas subdivididas, com 4 repetições, totalizando 144 unidades experimentais. Utilizou-se um trator, (4x2 TDA) com potência no motor de 63 kW (85 cv), tendo um escarificador acoplado, os dados foram registrados através de acelerômetros instalados no piso da cabina, na plataforma, no coxim e no assento. Concluiu-se que as magnitudes das acelerações eficazes obtidas, na interface assento-operador, em todos os 36 tratamentos, ficaram acima do limite de conforto na frequência de 1 a 80 Hz, estabelecidas pela norma (ISO 2631-1: 1997) para exposição de 8h diária do operador. As magnitudes das acelerações eficazes na direção vertical (z), no piso da cabina do trator, em todos os 36 tratamentos, tiveram índice confortável para a lastragem metálica total (LMT) e pouco desconfortável para a lastragem metálica parcial (LMP) e lastragem hidráulica total (LHT), de acordo com a (ISO 2631-1: 1997). A transmissibilidade de vibração na direção (z) através do coxim teve amplificação no intervalo de 0 a 15 Hz para a LMT, de 0 a 19 Hz para a LMP e de 71 a 76 Hz para a LHT. Os valores de transmissibilidade na análise de 1 a 80 Hz corresponderam a 59%, 74% e 88%, respectivamente para a LMT, LMP e LHT. Em todos os tratamentos a transmissibilidade de vibração do piso para o assento foi em torno de 20 vezes maior em relação à transmissibilidade da plataforma para o piso do trator, sendo a faixa frequência de 1 a 80 Hz. Na simulação dinâmica virtual, o elastômero utilizado proporcionou uma redução da magnitude de vibração na interface assento-operador, em torno de 11%, na direção vertical.