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Sample records for elastomeric gasket materials

  1. Degradation of elastomeric gasket materials in PEM fuel cells

    Polymer electrolyte membrane (PEM) fuel cell stack requires gaskets in each cell to keep the reactant gases within their respective regions. Long-term durability of the fuel cell stacks depends heavily on the functionality of the gaskets. Both the leachants from the seal materials and the cracking of the seals are of great concern to the overall durability of the fuel cell stacks. The degradation of four commercially available gasket materials was investigated in a PEM fuel cell environment in this study. Optical microscopy reveals that the degradation starts with surface roughness from the early stage of exposure and finally results in cracks over time. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were employed to study the surface chemistry of the gasket materials before and after exposure to the PEM fuel cell environment over time. Results from these analyses indicate that the surface chemistry changed initially as a manifestation of the chemical degradation and proceeded via de-cross-linking and chain scission in the backbone. Atomic adsorption spectrometry analysis was used to identify the leachants in the soaking solution from the gasket materials. The effect due to applied stress is reported as well

  2. [Elastomeric impression materials].

    Anagnostopoulos, T; Tsokas, K

    1990-01-01

    A review of the literature on elastomeric impression materials, is presented in this paper. The article mentions the composition and the most important properties of the elastomeric impression materials used in dental practice. The clinical significance of these materials, physical and mechanical properties are also emphasized. In addition some new elastomeric impression materials with improved properties and a new (experimental) light-cured impression material, are mentioned. Another part of this article is the biocompatibility of these materials. In the end the great significance of handling is outlined. PMID:2130039

  3. [Elastomeric impression materials].

    Levartovsky, S; Folkman, M; Alter, E; Pilo, R

    2011-04-01

    Elastomeric impression materials are in common use. The impression taken should be highly precise, thus, requiring specific care when manipulatingthese materials. There are 4 groups of elastomers; polysulfide, condensation silicone, addition silicone and polyether; each differ in their setting mechanism and their physical and chemical properties. This review elaborates the major properties of elastomers and its implications on their use. The impression material is inserted into the patient's mouth in a viscous state and transforms into viscoelastic state, upon withdrawal, influencing the residual deformation. The requirements are minimal residual deformation or maximal elastic recovery. As the mouth is a wet environment a major consideration is hydrophilicity. The wettability which is estimated by measuring either the contact angle of a droplet of water and the substrate post setting or the contact angle of a droplet of impression material and the wet tooth pre setting, determines the interaction of the material with both mouth fluids and gypsum. As the primary end target is to obtain a model depicting accurately the oral details, an attention to the impressions' compatibility with gypsum should also be given. Many studies were conducted to get a thorough understanding of the hydrophilic properties of each material, and the mechanism utilized, such as surfactants in hydrophilic PVS. Polyether is the only material that is truly hydrophilic; it exhibits the lowest contact angle, during and after setting. Recent studies show that during setting the Polyether hydrophilicity is increased compared to the condition after setting. Dimensional stability, a crucial property of the impression, is affected by the physical and chemical attributes of the material, such as its tear strength. Polysulfide has the highest tear strength. Tear Strength is affected by two major parameters, viscosity, a built-in property, and how fast the impression is pulled out of the mouth, the

  4. Elastomere seals/gaskets for gas supply pipes and district heating gas pipes. Einsatz von Dichtungen aus Elastomeren fuer Gasversorgungs- und Gasfernleitungen

    1982-06-01

    The leaflet applies to properties, storage, utilisation and installation of elastomere gaskets in gas supply lines and district gas heating pipes, as well as to their components in accordance with DIn 3535 part 3. Gas is transported at temperatures between -5deg C and +50deg C and operating pressures of up to 40 bar. (DG).

  5. Chemical degradation of five elastomeric seal materials in a simulated and an accelerated PEM fuel cell environment

    Lin, Chih-Wei [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 804 (China); Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Chien, Chi-Hui [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 804 (China); Tan, Jinzhu [College of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing, Jiangsu 210009 (China); Chao, Yuh J. [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Van Zee, J.W. [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2011-02-15

    Polymer electrolyte membrane (PEM) fuel cell stack requires gaskets and seals in each cell to keep the hydrogen and air/oxygen within their respective regions. The stability of the gaskets/seals is critical to the operating life as well as the electrochemical performance of the fuel cell. Chemical degradation of five elastomeric gasket materials in a simulated and an aggressive accelerated fuel cell solution at PEM operating temperature for up to 63 weeks was investigated in this work. The five materials are copolymeric resin (CR), liquid silicone rubber (LSR), fluorosilicone rubber (FSR), ethylene propylene diene monomer rubber (EPDM), and fluoroelastomer copolymer (FKM). Using optical microscopy, topographical changes on the sample surface due to the acidic environment were revealed. Weight loss of the test samples was monitored. Atomic absorption spectrometer analysis was performed to study the silicon, calcium, and magnesium leachants from the materials into the soaking solution. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy was employed to study the surface chemistry of the materials before and after exposure to the simulated fuel cell environment over time. Among the five materials studied, CR and LSR in the accelerated solution are not as stable as the other three materials. FSR appears to be the most stable. (author)

  6. A guide to the suitability of elastomeric seal materials for use in radioactive material transport packages

    Vince, D.J. [Department for Transport, London (United Kingdom)

    2004-07-01

    Elastomeric seals are a frequently favoured method of sealing Radioactive Material Transport (RMT) packages. The sealing technology has been proven for many years in a wide range of industrial applications. The requirements of the RMT package applications, however, are significantly different from those commonly found in other industries. This guide outlines the Regulatory performance requirements placed on an RMT package sealing system by TS-R-1, and then summarises the material, environment and geometry characteristics of elastomeric seals relevant to RMT applications. Tables in the guide list typical material properties for a range of elastomeric materials commonly used in RMT packages.

  7. A guide to the suitability of elastomeric seal materials for use in radioactive material transport packages

    Elastomeric seals are a frequently favoured method of sealing Radioactive Material Transport (RMT) packages. The sealing technology has been proven for many years in a wide range of industrial applications. The requirements of the RMT package applications, however, are significantly different from those commonly found in other industries. This guide outlines the Regulatory performance requirements placed on an RMT package sealing system by TS-R-1, and then summarises the material, environment and geometry characteristics of elastomeric seals relevant to RMT applications. Tables in the guide list typical material properties for a range of elastomeric materials commonly used in RMT packages

  8. Soft hydrogel materials from elastomeric gluten-mimetic proteins

    Bagheri, Mehran; Scott, Shane; Wan, Fan; Dick, Scott; Harden, James; Biomolecular Assemblies Team

    2014-03-01

    Elastomeric proteins are ubiquitous in both animal and plant tissues, where they are responsible for the elastic response and mechanical resilience of tissues. In addition to fundamental interest in the molecular origins of their elastic behaviour, this class of proteins has great potential for use in biomaterial applications. The structural and elastomeric properties of these proteins are thought to be controlled by a subtle balance between hydrophobic interactions and entropic effects, and in many cases their characteristic properties can be recapitulated by multi-block protein polymers formed from repeats of short, characteristic polypeptide motifs. We have developed biomimetic multi-block protein polymers based on variants of several elastomeric gluten consensus sequences. These proteins include constituents designed to maximize their solubility in aqueous solution and minimize the formation of extended secondary structure. Thus, they are examples of elastic intrinsically disordered proteins. In addition, the proteins have distributed tyrosine residues which allow for inter-molecular crosslinking to form hydrogel networks. In this talk, we present experimental and simulation studies of the molecular and materials properties of these proteins and their assemblies.

  9. Long-time dynamic compatibility of elastomeric materials with hydrazine

    Coulbert, C. D.; Cuddihy, E. F.; Fedors, R. F.

    1973-01-01

    The tensile property surfaces for two elastomeric materials, EPT-10 and AF-E-332, were generated in air and in liquid hydrazine environments using constant strain rate tensile tests over a range of temperatures and elongation rates. These results were used to predict the time-to-rupture for these materials in hydrazine as a function of temperature and amount of strain covering a span of operating times from less than a minute to twenty years. The results of limited sheet-folding tests and their relationship to the tensile failure boundary are presented and discussed.

  10. Performance testing of elastomeric seal materials under low and high temperature conditions: Final report

    The US Department of Energy Offices of Defense Programs and Civilian Radioactive Waste Management jointly sponsored a program to evaluate elastomeric O-ring seal materials for radioactive material shipping containers. The report presents the results of low- and high-temperature tests conducted on 27 common elastomeric compounds

  11. Performance testing of elastomeric seal materials under low and high temperature conditions: Final report

    BRONOWSKI,DAVID R.

    2000-06-01

    The US Department of Energy Offices of Defense Programs and Civilian Radioactive Waste Management jointly sponsored a program to evaluate elastomeric O-ring seal materials for radioactive material shipping containers. The report presents the results of low- and high-temperature tests conducted on 27 common elastomeric compounds.

  12. EXPERIMENTAL RESEARCHES OF ELASTOMERIC MATERIALS TO STABILIZE THE OSCILLATION OF POWER GRID STRUCTURES

    Iurii Priadko

    2015-12-01

    Full Text Available This paper proposes a new type of insulator, has both insulating and damping properties to improve the operational reliability of overhead power lines' structures (OHPL. In order to assess an effectiveness of the new insulator's design have made laboratory tests of a insulator model with different types of elastomer seals, differed of the rubber marks and the type of reinforcement. An experiment consist of two stages: at the first stage an object of study has been exposed to cyclical vibration, at the second – the impact of an impulsively load. Results of the research showed, that the most effective are the elastomeric gasket with a minimum rigidity characteristics without reinforcement. Using insulators with such dampers allows to reduce the first maximum impulse to a support by an average of 20% and reduce the frequency and amplitude characteristics of the system. Based on this was developed a new type of elastomer reinforcing with steel sheet elements in the form of a truncated cone.

  13. Developments in new aircraft tire tread materials. [fatigue life of elastomeric materials

    Yager, T. J.; Mccarty, J. L.; Riccitiello, S. R.; Golub, M. A.

    1976-01-01

    Comparative laboratory and field tests were conducted on experimental and state-of-the-art aircraft tire tread materials in a program aimed at seeking new elastomeric materials which would provide improved aircraft tire tread wear, traction, and blowout resistance in the interests of operational safety and economy. The experimental stock was formulated of natural rubber and amorphous vinyl polybutadiene to provide high thermal-oxidative resistance, a characteristic pursued on the premise that thermal oxidation is involved both in the normal abrasion or wear of tire treads and probably in the chain of events leading to blowout failures. Results from the tests demonstrate that the experimental stock provided better heat buildup (hysteresis) and fatigue properties, at least equal wet and dry traction, and greater wear resistance than the state-of-the-art stock.

  14. Lifetime Analysis of Rubber Gasket Composed of Methyl Vinyl Silicone Rubber with Low-Temperature Resistance

    Young-Doo Kwon

    2015-01-01

    Full Text Available Most machines and instruments constantly require elastomeric materials like rubber for the purposes of shock absorption, noise attenuation, and sealing. The material properties and accurate lifetime prediction of rubber are closely related to the quality of machines, especially their durability and reliability. The properties of rubber-like elastomers are influenced by ambient conditions, such as temperature, environment, and mechanical load. Moreover, the initial properties of rubber gaskets must be sustained under working conditions to satisfy their required function. Because of its technical merits, as well as its low cost, the highly accelerated life test (HALT is used by many researchers to predict the long-term lifetime of rubber materials. Methyl vinyl silicone rubber (VMQ has recently been adopted to improve the lifetime of automobile radiator gaskets. A four-parameter method of determining the recovery ability of the gaskets was recently published, and two revised methods of obtaining the recovery were proposed for polyacrylate (ACM rubber. The recovery rate curves for VMQ were acquired using the successive zooming genetic algorithm (SZGA. The gasket lifetime for the target recovery (60% of a compressed gasket was computed somewhat differently depending on the selected regression model.

  15. High k dielectric elastomeric materials for low voltage applications

    Walder, C.; Molberg, M.; Opris, D. M.; Nüesch, F. A.; Löwe, C.; Plummer, C. J. G.; Leterrier, Y.; Månson, J.-A. E.

    2009-03-01

    In principle EAP technology could potentially replace common motion-generating mechanisms in positioning, valve control, pump and sensor applications, where designers are seeking quieter, power efficient devices to replace conventional electrical motors and drive trains. Their use as artificial muscles is of special interest due to their similar properties in terms of stress and strain, energy and power densities or efficiency. A broad application of dielectric elastomer actuators (DEA) is limited by the high voltage necessary to drive such devices. The development of novel elastomers offering better intrinsic electromechanical properties is one way to solve the problem. We prepared composites from cross-linked silicone elastomers or thermoplastic elastomers (TPE) by blending them with organic fillers exhibiting a high dielectric constant. Well characterized monomeric phthalocyanines and modified doped polyaniline (PANI) were used as filler materials. In addition, blends of TPE and an inorganic filler material PZT were characterized as well. We studied the influence of the filler materials onto the mechanical and electromechanical properties of the resulting mixtures. A hundredfold increase of the dielectric constant was already observed for blends of an olefin based thermoplastic elastomer and PANI.

  16. Biodegradable and Elastomeric Poly(glycerol sebacate) as a Coating Material for Nitinol Bare Stent

    2014-01-01

    We synthesized and evaluated biodegradable and elastomeric polyesters (poly(glycerol sebacate) (PGS)) using polycondensation between glycerol and sebacic acid to form a cross-linked network structure without using exogenous catalysts. Synthesized materials possess good mechanical properties, elasticity, and surface erosion biodegradation behavior. The tensile strength of the PGS was as high as 0.28 ± 0.004 MPa, and Young's modulus was 0.122 ± 0.0003 MPa. Elongation was as high as 237.8 ± 0.64...

  17. The effect of rinsing time periods on wettability of elastomeric impression materials: in vitro study

    Özlem Acar

    2016-01-01

    Full Text Available OBJECTIVE: The aim of this study was to determine whether different rinsing time periods affected the wettability of polymerized elastomeric impression materials. MATERIALS AND METHOD: Panasil Contact Plus (PCP, Panasil Contact Non-Surfactant (PCNS, Panasil Initial Contact (PIC, Express (EXP and Impregum (IMP impression materials were tested. Standardized samples were rinsed with water for 10 s, 15 s or 20 s, and the wettability was determined by contact angle measurement through an evaluation period of 60 seconds (n=7. Non-rinsed groups were used as control. Measurements were made at 5 time points (at 0, 6, 15, 30 and 60 seconds. Kruskal Wallis test and Conover’s multiple comparison tests were used for all multiple comparisons. Bonferroni adjustment was applied for controlling Type I error (p0.002. CONCLUSION: Rinsing the surfactant-containing polyvinylsiloxane impression materials decreased their wettability, whereas no such effect was seen for the surfactant free polyvinylsiloxane and polyether impression materials.

  18. Glass interface effect on high-strain-rate tensile response of a soft polyurethane elastomeric polymer material

    Fan, J.T.; Weerheijm, J.; Sluys, L.J.

    2015-01-01

    The glass interface effect on dynamic tensile response of a soft polyurethane elastomeric polymer material has been investigated by subjecting a glass-polymer system of this polymer material matrix embedded a single 3 mm-diameter glass particle to impact loading in a split Hopkinson tension bar (SHT

  19. Utilizing stretch-tunable thermochromic elastomeric opal films as novel reversible switchable photonic materials.

    Schäfer, Christian G; Lederle, Christina; Zentel, Kristina; Stühn, Bernd; Gallei, Markus

    2014-11-01

    In this work, the preparation of highly thermoresponsive and fully reversible stretch-tunable elastomeric opal films featuring switchable structural colors is reported. Novel particle architectures based on poly(diethylene glycol methylether methacrylate-co-ethyl acrylate) (PDEGMEMA-co-PEA) as shell polymer are synthesized via seeded and stepwise emulsion polymerization protocols. The use of DEGMEMA as comonomer and herein established synthetic strategies leads to monodisperse soft shell particles, which can be directly processed to opal films by using the feasible melt-shear organization technique. Subsequent UV crosslinking strategies open access to mechanically stable and homogeneous elastomeric opal films. The structural colors of the opal films feature mechano- and thermoresponsiveness, which is found to be fully reversible. Optical characterization shows that the combination of both stimuli provokes a photonic bandgap shift of more than 50 nm from 560 nm in the stretched state to 611 nm in the fully swollen state. In addition, versatile colorful patterns onto the colloidal crystal structure are produced by spatial UV-induced crosslinking by using a photomask. This facile approach enables the generation of spatially cross-linked switchable opal films with fascinating optical properties. Herein described strategies for the preparation of PDEGMEMA-containing colloidal architectures, application of the melt-shear ordering technique, and patterned crosslinking of the final opal films open access to novel stimuli-responsive colloidal crystal films, which are expected to be promising materials in the field of security and sensing applications. PMID:25243892

  20. A general approach for quantifying the heat-ageing of gaskets

    A recurrent concern in the design of packaging for the transportation of radioactive material is to determine the elastomeric gaskets life at high temperature. Most gasket suppliers specify maximum allowable temperatures during ''continuous service'' and ''peak service'' (such as ''200 C in continuous service'' or ''250 C in peak'') but they do not specify the definition of ''continuous'' or ''peak'' service, what are the acceptance criteria and how these maximum temperatures are determined. Based on this type of data, it is difficult to assess the acceptability of a gasket submitted to fluctuating temperatures. COGEMA LOGISTICS has launched a test program on the different rubber grades used on its casks to determine, for different temperature levels (e.g. 200 C, 210 C,.., 250 C..), the maximum seal life based on clearly defined criteria. The goal is to establish, for each rubber grade, the seal life versus temperature curve. These curves can be used to know if a gasket exposed to any specified temperature profile can guarantee the leaktightness. The principle of the method is to calculate a sum of ''elementary damage rates'' on the temperature profile (split up into elementary time intervals) and to compare this sum (the ''global damage rate'') to a ''aximum permissible damage rate''. If the global damage rate is lower than the maximum permissible damage rate, the leaktightness of the packaging can be guaranteed for the given temperature profile

  1. Development and evaluation of elastomeric materials for geothermal applications. Annual report, October 1977-December 1978

    Mueller, W.A.; Kalfayan, S.H.; Reilly, W.W.; Yavrouian, A.H.; Mosesman, I.D.; Ingham, J.D.

    1979-05-15

    The research involved formulation of commercially available materials and synthesis of new elastomers. Formulation studies at JPL and elsewhere produced a material having about 250-350 psi tensile strength and 30 to 80% elongation at 260/sup 0/C for at least 24 hours in simulated brine. The relationship between these laboratory test results and sealing performance in actual or simulated test conditions is not entirely clear; however, it is believed that no conventional formation or casing packer design is likely to perform well using these materials. The synthetic effort focused on high temperature block copolymers and development of curable polystyrene. Procedures were worked out for synthesizing these new materials. Initial results with heat-cured unfilled polystyrene gum at 260/sup 0/C indicated a tensile strength of about 50 psi. Cast films of the first sample of polyphenyl quinoxaline-polystyrene block copolymer, which has a graft-block structure consisting of a polystyrene chain with pendant polyphenyl quinoxaline groups, showed elastomeric behavior in the required temperature range. Its tensile strength and elongation at 260/sup 0/C were 220 to 350 psi and 18 to 36%, respectively. All of these materials also showed satisfactory hydrolytic stability. A procedure for the synthesis of a linear block copolymer of this type has been devised, and the required new intermediates have been synthesized and characterized. A description of the previous year's work is included in an appendix.

  2. A Study of Durability for Elastomeric Fuel Cell Seals and an Examination of Confinement Effects in Elastomeric Joints

    Klein, Justin

    2010-01-01

    Proton exchange membrane fuel cells typically consist of stacks of membrane electrode assemblies sandwiched between bipolar plates, effectively combining the individual cells in series to achieve the desired voltage levels. Elastomeric gaskets are commonly used between each cell to insure that the reactant gases are isolated; any failure of a fuel cell gasket can cause the reactants to mix, which may lead to failure of the fuel cell. An investigation of the durability of these fuel cell seals...

  3. Linear dimensional changes in plaster die models using different elastomeric materials

    Jefferson Ricardo Pereira

    2010-09-01

    Full Text Available Dental impression is an important step in the preparation of prostheses since it provides the reproduction of anatomic and surface details of teeth and adjacent structures. The objective of this study was to evaluate the linear dimensional alterations in gypsum dies obtained with different elastomeric materials, using a resin coping impression technique with individual shells. A master cast made of stainless steel with fixed prosthesis characteristics with two prepared abutment teeth was used to obtain the impressions. References points (A, B, C, D, E and F were recorded on the occlusal and buccal surfaces of abutments to register the distances. The impressions were obtained using the following materials: polyether, mercaptan-polysulfide, addition silicone, and condensation silicone. The transfer impressions were made with custom trays and an irreversible hydrocolloid material and were poured with type IV gypsum. The distances between identified points in gypsum dies were measured using an optical microscope and the results were statistically analyzed by ANOVA (p < 0.05 and Tukey's test. The mean of the distances were registered as follows: addition silicone (AB = 13.6 µm, CD=15.0 µm, EF = 14.6 µm, GH=15.2 µm, mercaptan-polysulfide (AB = 36.0 µm, CD = 36.0 µm, EF = 39.6 µm, GH = 40.6 µm, polyether (AB = 35.2 µm, CD = 35.6 µm, EF = 39.4 µm, GH = 41.4 µm and condensation silicone (AB = 69.2 µm, CD = 71.0 µm, EF = 80.6 µm, GH = 81.2 µm. All of the measurements found in gypsum dies were compared to those of a master cast. The results demonstrated that the addition silicone provides the best stability of the compounds tested, followed by polyether, polysulfide and condensation silicone. No statistical differences were obtained between polyether and mercaptan-polysulfide materials.

  4. Nuclear power plant accident simulations of gasket materials under simultaneous radiation plus thermal plus mechanical stress conditions

    In order to probe the response of silicone door gasket materials to a postulated severe accident in an Italian nuclear power plant, compression stress relaxation (CSR) and compression set (CS) measurements were conducted under combined radiation (approximately 6 kGy/h) and temperature (up to 230 degrees C) conditions. By making some reasonable initial assumptions, simplified constant temperature and dose rates were derived that should do a reasonable job of simulating the complex environments for worst-case severe events that combine overall aging plus accidents. Further simplification coupled with thermal-only experiments allowed us to derive thermal-only conditions that can be used to achieve CSR and CS responses similar to those expected from the combined environments that are more difficult to simulate. Although the thermal-only simulations should lead to sealing forces similar to those expected during a severe accident, modulus and density results indicate that significant differences in underlying chemistry are expected for the thermal-only and the combined environment simulations. 15 refs., 31 figs., 15 tabs

  5. A general approach for quantifying the heat-ageing of gaskets

    Andre, R.; Malesys, P. [COGEMA Logistics, Saint-Quentin-en-Yvelines (France)

    2004-07-01

    A recurrent concern in the design of packaging for the transportation of radioactive material is to determine the elastomeric gaskets life at high temperature. Most gasket suppliers specify maximum allowable temperatures during ''continuous service'' and ''peak service'' (such as ''200 C in continuous service'' or ''250 C in peak'') but they do not specify the definition of ''continuous'' or ''peak'' service, what are the acceptance criteria and how these maximum temperatures are determined. Based on this type of data, it is difficult to assess the acceptability of a gasket submitted to fluctuating temperatures. COGEMA LOGISTICS has launched a test program on the different rubber grades used on its casks to determine, for different temperature levels (e.g. 200 C, 210 C,.., 250 C..), the maximum seal life based on clearly defined criteria. The goal is to establish, for each rubber grade, the seal life versus temperature curve. These curves can be used to know if a gasket exposed to any specified temperature profile can guarantee the leaktightness. The principle of the method is to calculate a sum of ''elementary damage rates'' on the temperature profile (split up into elementary time intervals) and to compare this sum (the ''global damage rate'') to a ''aximum permissible damage rate''. If the global damage rate is lower than the maximum permissible damage rate, the leaktightness of the packaging can be guaranteed for the given temperature profile.

  6. Attachment of bacteria to teflon and buna-n-rubber gasket materials

    Gaspar-Rolle, Maria Nelma Pinto

    1991-01-01

    Surface analysis of buna-N-rubber and teflon was performed. Scanning electron microscopy was used to analyze the topography of both materials and x-ray microanalysis identified the elemental chemical composition of the polymers. Teflon was primarily a smooth surface with random irregular spots, while buna-N-rubber had a very rough topography with "caverns" and crevices spread over the surface. The x-ray microanalysis showed that there are no impurities on the surface of teflon; however, c...

  7. A thermo-mechanically coupled theory for fluid permeation in elastomeric materials: Application to thermally responsive gels

    Chester, Shawn A.; Anand, Lallit

    2011-10-01

    An elastomeric gel is a cross-linked polymer network swollen with a solvent, and certain gels can undergo large reversible volume changes as they are cycled about a critical temperature. We have developed a continuum-level theory to describe the coupled mechanical deformation, fluid permeation, and heat transfer of such thermally responsive gels. In discussing special constitutive equations we limit our attention to isotropic materials, and consider a model based on a Flory-Huggins model for the free energy change due to mixing of the fluid with the polymer network, coupled with a non-Gaussian statistical-mechanical model for the change in configurational entropy—a model which accounts for the limited extensibility of polymer chains. We have numerically implemented our theory in a finite element program. We show that our theory is capable of simulating swelling, squeezing of fluid by applied mechanical forces, and thermally responsive swelling/de-swelling of such materials.

  8. Low-temperature behavior of elastomeric seals. Material property determination for the use in transport and storage casks for radioactive materials; Tieftemperaturverhalten von Elastomerdichtungen. Eigenschaftsbestimmung fuer den Einsatz in Transport- und Lagerbehaeltern fuer radioaktive Stoffe

    Jaunich, Matthias; Wolff, Dietmar; Stark, Wolfgang [BAM Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany)

    2010-05-15

    Elastomers are used as sealing materials for radioactive waste transport and storage casks. Due to the valid laws and guidelines for these containers the tightness of the elastomeric seals has to be demonstrated for temperature down to -40 C. Therefore the low-temperature behavior of elastomeric seals and the failure mechanism inducing leak rates above the limiting value are of interest. Material properties of elastomeric polymers are significantly temperature dependent, in the low temperature range due to the rubber-glass transition. The measurement of the dynamic storage modulus and the glass transition temperature was performed using dynamic mechanical analysis. Further measurements are necessary to determine the failure temperature of elastomeric seals. The authors show that EPDM is still in the rubber-elastic range at -40 C.

  9. Behavior of a New Elastomeric material used as polyolefinic geo membrane in waterproofing; Comportamiento de un nuevo material elastomerico utilizado como geomembrana poliolefinica en impermeabilizacion

    Blanco, M.; Aguilar, E.; Vara, T. A; Soriano, J.; Garcia, F.; Castillo, F.

    2011-07-01

    Two decades ago that Balsas de Tenerife (BALTEN) and the Centro de Estudios y Experimentacion de Obras Publicas (CEDEX), in its experimental field of the south of the Tenerife Island have installed a series of materials to known their behaviour over time. These products among which was placed over a dozen years ago, on an elastomeric polyolefin. This work presents the performance of this synthetic geo membrane, focusing on the evolution in the time of the tensile properties static puncture, low temperature folding, dynamic impact, joint strength (shear and peeling test), optical microscopy of reflection nd scanning electron microscopy. (Author) 11 refs.

  10. Relaxation behaviour of gasketed joints during assembly using finite element analysis

    Muhammad Abid; Saad Hussain

    2010-02-01

    Gasketed bolted flange pipe joints are always prone to leakage during operating conditions. Therefore, performance of a gasketed flange joint is very much dependent on the proper joint assembly with proper gasket, proper gasket seating stress and proper pre-loading in the bolts of a joint. For a gasketed flange joint, the two main concerns are the joint strength and the sealing capability. To investigate these, a detailed three-dimensional nonlinear finite element analysis of a gasketed joint is carried out using gasket as a solid plate. Bolt scatter, bolt bending and bolt relaxation are concluded as the main factors affecting the joint’s performance. In addition, the importance of proper bolt tightening sequence, number of passes influence of elastic and elasto-plastic material modelling on joint performance are also presented. A dynamic mode in a gasketed joint is concluded, which is the main reason for its failure.

  11. Properties of a new polyether urethane dimethacrylate photoinitiated elastomeric impression material.

    Craig, R G; Hare, P H

    1990-01-01

    The photoinitiated impression material is supplied premixed as a light-bodied material in a light-tight plastic syringe and as a heavy-bodied material in a tube. The impression material has excellent physical, mechanical, and clinical qualities with noteworthy long working times, short setting times, dimensional stability, accuracy, high tear strength, good wettability, biocompatibility, and ease of cold disinfection without loss of quality. The impression material is also compatible with gypsum and silver or copper metallizing baths. Accurate casts can be obtained by means of either a double-impression technique or a double-mix technique. PMID:2295985

  12. Geothermal elastomeric materials. Twelve-months progress report, October 1, 1976--September 30, 1977

    Hirasuna, A.R.; Bilyeu, G.D.; Davis, D.L.; Stephens, C.A.; Veal, G.R.

    1977-12-01

    Progress is reported on efforts to develop elastomers for packer seal element applications which will survive downhole geothermal well chemistry at 260/sup 0/C (500/sup 0/F) for 24 hours. To achieve this development, a three level elastomer testing and evaluation program was established. The first level Screening Tests is a broad screening of potential candidates and with the end objective to filter out the more promising candidates for more expensive subsequent testing. The battery of tests include standard ASTM tests and a special test developed to test extrusion resistance using specimens all made from sheet stock. The second level or Simulation Tests provide a laboratory equivalent of downhole conditions using synthetic geothermal fluid. Full scale packer seals are tested under simulated operational conditions by a test fixture. The third level or In-Situ Tests which are currently in the planning, provide for testing the most favored materials in-situ in the geothermal well. A test module provides for testing of the specimen without interfacing with the well casing. A test module freely hanging on a wireline has much lower probability of causing a problem, such as becoming lodged in the well, as compared to an operational casing packer. This maximizes the number of wells (hence geothermal environments) where access can be gained and In-Situ Testing performed. During this period commercially available polymers were investigated. Most of the work centered around formulating peroxide cured Vitons and some on EPDMs, butyls, and resin cured Vitons. Of the formulations tested to date the EPDMs appear most promising and the peroxide cured Vitons next most promising. However, data is too sparse to make any firm conclusions at this time. Minor tasks were performed evaluating current commercially available elastomers used in oil tools and conceptualization of casing packer for the geothermal application.

  13. A simple aluminum gasket for use with both stainless steel and aluminum flanges

    A technique has been developed for making aluminum wire seal gaskets of various sizes and shapes for use with both stainless steel and aluminum alloy flanges. The gasket material used is 0.9999 pure aluminum, drawn to a diameter of 3 mm. This material can be easily welded and formed into various shapes. A single gasket has been successfully used up to five times without baking. The largest gasket tested to date is 3.5 m long and was used in the shape of a parallelogram. Previous use of aluminum wire gaskets, including results for bakeout at temperatures from 20 to 660 degree C, is reviewed. A search of the literature indicates that this is the first reported use of aluminum wire gaskets for aluminum alloy flanges. The technique is described in detail, and the results are summarized. 11 refs., 4 figs

  14. Decrease of reaction force of metal gaskets just after initial tightening

    The decrease of reaction force of some metal gaskets inserted into the test flange at room temperature, 120 C(real cask temperature) and 200 C(accelerated condition) are measured. The reaction forces of metal gaskets in the room temperature have been almost not changed. The reaction force of 120 C and 200 C metal gaskets has decreased according to the temperature increase. After the temperature became stable, the decrease of the reaction force gradually proceeded, this decrease have been as same as previous studies. The bolts of transport and storage casks are usually tightened just after the loading of spent fuels, and then the temperature of metal gaskets at that time is almost the room temperature. The reaction forces of the metal gasket tightened at this condition would be decreased after the temperature increase due to the decay heat of spent fuels. It is confirmed that the loosening of the bolts might be happened if the tightening torque of bolts is not appropriate. It is easy to evaluate that the reaction forces of the metal gasket in storage condition according to Larson-Miller parameter or relaxation of the gasket material, but the decrease of the reaction forces of the metal gasket just after the loading is not able to evaluate by these method. It is necessary to evaluate the reaction forces according to plastic deformation property of the metal gaskets so as to fasten the gaskets safety

  15. Embedded Strain Gauges for Condition Monitoring of Silicone Gaskets

    Timo Schotzko

    2014-07-01

    Full Text Available A miniaturized strain gauge with a thickness of 5 µm is molded into a silicone O-ring. This is a first step toward embedding sensors in gaskets for structural health monitoring. The signal of the integrated sensor exhibits a linear correlation with the contact pressure of the O-ring. This affords the opportunity to monitor the gasket condition during installation. Thus, damages caused by faulty assembly can be detected instantly, and early failures, with their associated consequences, can be prevented. Through the embedded strain gauge, the contact pressure applied to the gasket can be directly measured. Excessive pressure and incorrect positioning of the gasket can cause structural damage to the material of the gasket, which can lead to an early outage. A platinum strain gauge is fabricated on a thin polyimide layer and is contacted through gold connections. The measured resistance pressure response exhibits hysteresis for the first few strain cycles, followed by a linear behavior. The short-term impact of the embedded sensor on the stability of the gasket is investigated. Pull-tests with O-rings and test specimens have indicated that the integration of the miniaturized sensors has no negative impact on the stability in the short term.

  16. Embedded strain gauges for condition monitoring of silicone gaskets.

    Schotzko, Timo; Lang, Walter

    2014-01-01

    A miniaturized strain gauge with a thickness of 5 µm is molded into a silicone O-ring. This is a first step toward embedding sensors in gaskets for structural health monitoring. The signal of the integrated sensor exhibits a linear correlation with the contact pressure of the O-ring. This affords the opportunity to monitor the gasket condition during installation. Thus, damages caused by faulty assembly can be detected instantly, and early failures, with their associated consequences, can be prevented. Through the embedded strain gauge, the contact pressure applied to the gasket can be directly measured. Excessive pressure and incorrect positioning of the gasket can cause structural damage to the material of the gasket, which can lead to an early outage. A platinum strain gauge is fabricated on a thin polyimide layer and is contacted through gold connections. The measured resistance pressure response exhibits hysteresis for the first few strain cycles, followed by a linear behavior. The short-term impact of the embedded sensor on the stability of the gasket is investigated. Pull-tests with O-rings and test specimens have indicated that the integration of the miniaturized sensors has no negative impact on the stability in the short term. PMID:25014099

  17. Evaluation of Force Degradation Pattern of Elastomeric Ligatures and Elastomeric Separators in Active Tieback State

    Mohammadi, Amir; Mahmoodi, Farhang

    2015-01-01

    Background and aims. The purpose of this study was to evaluate initial force and force decay of commercially available elastomeric ligatures and elastomeric separators in active tieback state in a simulated oral environment. Materials and methods. A total of 288 elastomeric ligatures and elastomeric separators from three manufacturers (Dentaurum, RMO, 3M Unitek) were stretched to 100% and 150% of their original inner diameter. Force levels were measured initially and at 3-minute, 24-hour, and 1-, 2-, 3- and 4-week intervals. Data were analyzed by univariate analysis of variance and a post hoc Tukey test. Results. The means of initial forces of elastomeric ligatures and separators from three above-mentioned companies, when stretched to 100% of their inner diameters, were 199, 305 and 284 g, and 330, 416, 330 g; when they were stretched to 150% of their inner diameters the values were 286, 422 and 375 g, and 433, 540 and 504 g, respectively. In active tieback state, 11-18% of the initial force of the specimens was lost within the first 3 minutes and 29-63% of the force decay occurred in the first 24 hours; then force decay rate decreased. 62-81% of the initial force was lost in 4 weeks. Although force decay pattern was identical in all the products, the initial force and force decay of Dentaurum elastomeric products were less than the similar products of other companies (P<0.05). Under the same conditions, the force of elastomeric separators was greater than elastomeric ligatures of the same company. Conclusion. Regarding the force pattern of elastomeric ligatures and separators and optimal force for tooth movement, many of these products can be selected for applying orthodontic forces in active tieback state. PMID:26889363

  18. Conductive elastomeric extensometer

    Gause, R. L.; Glenn, C. G. (Inventor)

    1974-01-01

    An extensometer was used for measuring surface area changes of the human body caused by expansion and contraction of the body. A relatively thin and wide strain responsive conductive elastomeric band was adapted for application to a part of the body, such as around a limb or the trunk of the body. The elastomeric band is incorporated as a resistor in a balanced bridge circuit. Expansion or contraction of the portion of the body on which the elastomeric band is applied causes a change in the resistance of the band and a resultant imbalance of the bridge circuit. The output of the amplifier in volts is suitable for proving the desired reading through a recorder, oscilloscope or voltmeter.

  19. Polycarbosilazane passivation on graphite foil used as gasket seal

    Gasket seals are often used in industry and laboratories where a leak-proof installation is needed in order to avoid loss of products or dangerous materials. Many of products transported inside tubes are at relatively high temperatures excluding polymeric gaskets. In the same line, many of transported materials contain solvents which can attack polymer sealings, therefore limiting their use. An alternative is to use graphite joints as sealings. These joints are a sandwich of graphite foil and stainless steel mesh as forming core. The problem that raises using graphite in contact with steel is that at temperatures of about 500 °C an interdiffusion of carbon on the steel structure occurs which produces adhesion of the graphite gasket on the metallic flange. Therefore this adhesion increases the time to change each gasket, since rests of previously adhered graphite has to be removed from the flange. In order to avoid the adhesion of the graphite on the flange, polycarbosilazane precursor was used as protective finishing on the graphite foil surface. After thermal transformation of the polymer into the corresponding PDC finishing, it acts in two manners: It avoids the direct contact between the carbon and the steel and it allows the sealing of liquids and gases. Adhesion tests were done and showed that the foils passivated with PDCs did not adhere to the steel flange. Moreover, the production methods and products are compatible to industrial environment and processes. The results found here show that the time to change the gasket in industry can be clearly reduced by using the PDC finishing on graphite gasket

  20. Production and Analysis of the Properties of Non-asbestos Material Gasket by BA%抄取无石棉垫片的制备及性能研究∗

    贾有东; 刘美红

    2014-01-01

    石棉材料对环境及人体健康都会带来严重危害,简要介绍了生产无石棉垫片所采用的工艺。因胶乳抄取法具有小型化和易操作等优点,主要对胶乳抄取法进行了总结归纳,并从中找出影响垫片性能的主要工艺参数;同时,对采用该工艺所制得的无石棉垫片的性能进行了介绍,找出了制备无石棉垫片的材料配比,以期为研制出价格更低、应用更广和综合性能更好的非石棉垫片提供参考。%The asbestos material will bring serious harm to environment and human health,so the processes used to the production of non-asbestos gasket were introduced in the paper,among these processes,Beater-Addition process has the ad-vantages of miniaturization,and it is easy to operate,so the method was summarized,from which the main factors that af-fect the properties of the non-asbestos material gasket are found.Meanwhile,to give the references for us to study a kind of cheaper and more widely used,comprehensive performance compound non-asbestos material,to find out the optimal ratio of non-asbestos material,the properties were also summed up.

  1. Basic Investigations on Metallic and Composite Gaskets for an Application in SOFC Stacks

    Bram, M.; Reckers, S.; Drinovac, P.; Bruenings, S. E.; Steinbrech, R. W.; Buchkremer, H. P.; St oever, D.

    2002-06-01

    Metallic gaskets are promising candidates for sealing of SOFC stacks considering their favorable combination of elastic and plastic deformation (e.g. tolerance against mismatch of thermal expansion coefficients and closing of small surface imperfections like scratches and pits). However, their susceptibility to extensive creep under SOFC operation conditions limits their use. To overcome the creep problem the application of suitable spacer or filler materials such as mica was investigated. Results are presented, which elucidate the influence of contact load on the deformation and sealing of various metallic gaskets and composites of metallic gaskets with anorganic filler materials. (author)

  2. A finite strain thermo-viscoelastic constitutive model to describe the self-heating in elastomeric materials during low-cycle fatigue

    Ovalle Rodas, C.; Zaïri, F.; Naït-Abdelaziz, M.

    2014-03-01

    A thermo-visco-hyperelastic constitutive model, in accordance with the second thermodynamics principle, is formulated to describe the self-heating evolution in elastomeric materials under cyclic loading. The mechanical part of the model is based upon a Zener rheological representation in which the specific free energy potential is dependent on an added internal variable, allowing the description of the time-dependent mechanical response. The large strain mechanical behavior is described using a Langevin spring, while the continuous stress-softening under cyclic loading is taken into account by means of a network alteration kinetics. The thermo-mechanical coupling is defined by postulating the existence of a dissipation pseudo-potential, function of the viscous dilatation tensor. The proposed model is fully three-dimensional and is implemented into a finite element code. The model parameters are identified using experimental data obtained on a styrene-butadiene rubber under a given strain rate for different strain conditions. Predicted evolutions given by the model for other strain rates are found in good agreement with the experimental data.

  3. Elastomeric hoof boots

    Hanley, John

    2003-01-01

    The design, manufacture and testing of a prototype elastomeric equine boot is described in this thesis. Thoroughbred horses may suffer from a number of serious hoof disorders. These include stone bruising, navicular syndrome and hoof wall separation. Excessive concussion in the equine hoof is a major contributory factor in most of the problems horses experience in their lower limbs. Bandaging of a horses foot after injury is time consuming as well as being labour intensive. The proposed boot ...

  4. Elastomeric actuator devices for magnetic resonance imaging

    Dubowsky, Steven (Inventor); Hafez, Moustapha (Inventor); Jolesz, Ferenc A. (Inventor); Kacher, Daniel F. (Inventor); Lichter, Matthew (Inventor); Weiss, Peter (Inventor); Wingert, Andreas (Inventor)

    2008-01-01

    The present invention is directed to devices and systems used in magnetic imaging environments that include an actuator device having an elastomeric dielectric film with at least two electrodes, and a frame attached to the actuator device. The frame can have a plurality of configurations including, such as, for example, at least two members that can be, but not limited to, curved beams, rods, plates, or parallel beams. These rigid members can be coupled to flexible members such as, for example, links wherein the frame provides an elastic restoring force. The frame preferably provides a linear actuation force characteristic over a displacement range. The linear actuation force characteristic is defined as .+-.20% and preferably 10% over a displacement range. The actuator further includes a passive element disposed between the flexible members to tune a stiffness characteristic of the actuator. The passive element can be a bi-stable element. The preferred embodiment actuator includes one or more layers of the elastomeric film integrated into the frame. The elastomeric film can be made of many elastomeric materials such as, for example, but not limited to, acrylic, silicone and latex.

  5. Integrated-fin gasket for palm cubic-anvil high pressure apparatus

    Cheng, J.-G. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Matsubayashi, K.; Nagasaki, S.; Hisada, A.; Hirayama, T.; Uwatoko, Y. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Hedo, M. [Faculty of Science, University of Ryukyus, Senbaru, Nishihara, Okinawa 903-0213 (Japan); Kagi, H. [Graduate School of Science, University of Tokyo, 7-3-1, Hongo Bunkyo-Ku, Tokyo 113-0033 (Japan)

    2014-09-15

    We described an integrated-fin gasket technique for the palm cubic-anvil apparatus specialized for the high-pressure and low-temperature measurements. By using such a gasket made from the semi-sintered MgO ceramics and the tungsten-carbide anvils of 2.5 mm square top, we successfully generate pressures over 16 GPa at both room and cryogenic temperatures down to 0.5 K. We observed a pressure self-increment for this specific configuration and further characterized the thermally induced pressure variation by monitoring the antiferromagnetic transition temperature of chromium up to 12 GPa. In addition to enlarge the pressure capacity, such a modified gasket also improves greatly the surviving rate of electrical leads hanging the sample inside a Teflon capsule filled with the liquid pressure-transmitting medium. These improvements should be attributed to the reduced extrusion of gasket materials during the initial compression.

  6. Integrated-fin gasket for palm cubic-anvil high pressure apparatus

    We described an integrated-fin gasket technique for the palm cubic-anvil apparatus specialized for the high-pressure and low-temperature measurements. By using such a gasket made from the semi-sintered MgO ceramics and the tungsten-carbide anvils of 2.5 mm square top, we successfully generate pressures over 16 GPa at both room and cryogenic temperatures down to 0.5 K. We observed a pressure self-increment for this specific configuration and further characterized the thermally induced pressure variation by monitoring the antiferromagnetic transition temperature of chromium up to 12 GPa. In addition to enlarge the pressure capacity, such a modified gasket also improves greatly the surviving rate of electrical leads hanging the sample inside a Teflon capsule filled with the liquid pressure-transmitting medium. These improvements should be attributed to the reduced extrusion of gasket materials during the initial compression

  7. Influence of Custom Trays, Dual-Arch Passive, Flexed Trays and Viscosities of Elastomeric Impression Materials on Working Dies

    Kohli, Shivani; Kalsi, Rupali

    2016-01-01

    Introduction Dual arch impression technique signifies an essential improvement in fixed prosthodontics and has numerous benefits over conventional impression techniques. The accuracy of working dies fabricated from dual arch impression technique remains in question because there is little information available in the literature. Aim This study was conducted to compare the accuracy of working dies fabricated from impressions made from two different viscosities of impression materials using metal, plastic dual arch trays and custom made acrylic trays. Materials and Methods The study samples were grouped into two groups based on the viscosity of impression material used i.e. Group I (monophase), whereas Group II consisted of Dual Mix technique using a combination of light and heavy body material. These were further divided into three subgroups A, B and C depending on the type of impression tray used (metal dual arch tray, plastic dual arch tray and custom made tray). Measurements of the master cast were made using profile projector. Descriptive statistics like mean, Standard Deviation (SD) were calculated for all the groups. One way analysis of variance (ANOVA) was used for multiple group comparisons. A p-value of 0.05 or less was considered statistically significant. Results The gypsum dies obtained with the three types of impression trays using two groups of impression materials were smaller than the master models in dimensions. Conclusion The plastic dual arch trays produced dies which were the least accurate of the three groups. There was no significant difference in the die dimensions obtained using the two viscosities of impression materials. PMID:27437342

  8. Silicone foam molding method for sealing timing belt cover gasket; Timing belt gasket no happo silicone gomu tofu gijutsu

    Kobayashi, Y.; Kagosaki, T.; Omura, S.; Yamaguchi, H. [Toyota Motor Corp., Aichi (Japan)

    1995-04-20

    An automated assembly of a timing belt cover gasket succeeded by changing a gasket material from molding rubber to silicone foam rubber and making a coating application process with the change. Since a conventional molding rubber gasket was unstable to shape and difficult to integrate in the automation, a method was examined for applying a liquid silicone foam rubber, a building material. A silicone foam rubber as a building material had problems such that reaction was fast after two liquids were mixed, that hardening occurred in the mixed part, and that the viscosity was so low as to make a 3-dimensional application impossible. Consequently, a material was developed for a two-liquid heat setting type that commenced reaction by heating. An application process excellent in quality and yield was completed. In the system containing a device for mixing and discharging two liquids, by enlarging the bore diameter of a discharge nozzle, cutting liquid at the tip end of the nozzle, making a mixer with a small number of revolution and small capacity, using the material in which reaction starting temperature was raised to suppress the reaction inside the mixer, and so on. Thus, the automation was successfully carried out. 16 figs., 1 tab.

  9. The flow Rate Accuracy of Elastomeric Infusion Pumps After Repeated Filling

    Mohseni, Masood; Ebneshahidi, Amin

    2014-01-01

    Background: One of the frequent applications of elastomeric infusion pumps is postoperative pain management. In daily practice, the disposable pumps get refilled with modified medication combinations in the successive days; although, the accuracy of infusion rates is unknown to clinicians. Objectives: Our aim was to evaluate the effect of repeated filling on the delivery rate accuracy of an elastomeric pump available in our market. Materials and Methods: We examined 10 elastomeric infusion pu...

  10. Electrically conductive composites based on an elastomeric matrix filled with expanded graphite as a potential oil sensing material

    The preparation and properties of electrically conductive polymeric composites based on an elastomer matrix (styrene-isoprene styrene block copolymer) filled with expanded graphite are reported in this paper. The developed materials were tested as oil sensors in various modes. The operation of this sensor is based on changes in the electrical resistance R of the composites when exposed to oil. This phenomenon involves both simple geometrical changes and changes in inherent material characteristics such as the specific electrical conductivity (resistivity). An original method for the improvement of the sensors’ response rate based on the application of stretched sensing films was developed. Slightly stretched films (by 4% of the original length) showed a response that was 12.5 times faster with respect to oil absorption than an un-stretched film. The specific electrical conductivity of a material strongly depends on the extent to which it is stretched. For a composite filled with 10 wt.% of the filler, it was found that the electrical conductivity remained constant up to 11% of the sample extension before sharply decreasing. It was also found that an increase in the filler content reduced the response rate of the sensors. (paper)

  11. Compatibility Study for Plastic, Elastomeric, and Metallic Fueling Infrastructure Materials Exposed to Aggressive Formulations of Ethanol-blended Gasoline

    Kass, Michael D [ORNL; Pawel, Steven J [ORNL; Theiss, Timothy J [ORNL; Janke, Christopher James [ORNL

    2012-07-01

    In 2008 Oak Ridge National Laboratory began a series of experiments to evaluate the compatibility of fueling infrastructure materials with intermediate levels of ethanol-blended gasoline. Initially, the focus was elastomers, metals, and sealants, and the test fuels were Fuel C, CE10a, CE17a and CE25a. The results of these studies were published in 2010. Follow-on studies were performed with an emphasis on plastic (thermoplastic and thermoset) materials used in underground storage and dispenser systems. These materials were exposed to test fuels of Fuel C and CE25a. Upon completion of this effort, it was felt that additional compatibility data with higher ethanol blends was needed and another round of experimentation was performed on elastomers, metals, and plastics with CE50a and CE85a test fuels. Compatibility of polymers typically relates to the solubility of the solid polymer with a solvent. It can also mean susceptibility to chemical attack, but the polymers and test fuels evaluated in this study are not considered to be chemically reactive with each other. Solubility in polymers is typically assessed by measuring the volume swell of the polymer exposed to the solvent of interest. Elastomers are a class of polymers that are predominantly used as seals, and most o-ring and seal manufacturers provide compatibility tables of their products with various solvents including ethanol, toluene, and isooctane, which are components of aggressive oxygenated gasoline as described by the Society of Automotive Engineers (SAE) J1681. These tables include a ranking based on the level of volume swell in the elastomer associated with exposure to a particular solvent. Swell is usually accompanied by a decrease in hardness (softening) that also affects performance. For seal applications, shrinkage of the elastomer upon drying is also a critical parameter since a contraction of volume can conceivably enable leakage to occur. Shrinkage is also indicative of the removal of one or more

  12. Spanning forests on the Sierpinski gasket

    Shu-Chiuan Chang

    2008-04-01

    Full Text Available We present the numbers of spanning forests on the Sierpinski gasket $SG_d(n$ at stage $n$ with dimension $d$ equal to two, three and four, and determine the asymptotic behaviors. The corresponding results on the generalized Sierpinski gasket $SG_{d,b}(n$ with $d=2$ and $b=3,4$ are obtained. We also derive the upper bounds of the asymptotic growth constants for both $SG_d$ and $SG_{2,b}$.

  13. XY model on a Sierpinski gasket

    Correlation functions and topological excitations of the XY model on a Sierpinski gasket are studied. The energy of a vortex is shown to be finite, so no Berezinskii-Kosterlitz-Thouless transition can be expected to take place. At any temperature the correlation function decays exponentially at large distances. A form of the XY model on a Sierpinski gasket is found that allows for exact renormalization. The results obtained can be applied to superconducting wire networks and tunnel-junction arrays

  14. New single-layer steel gasket; Neuartige Einlagen-Stahl-Zylinderkopfdichtung

    Cierocki, K.; Schmitt, K.; Heilig, M.; Hilgert, C. [Goetze Payen, Herdorf (Germany)

    1998-05-01

    Since the ban on the use of asbestos fibres in cylinder head gaskets in Europe, engine developers have essentially had two options for gasket materials, namely modern soft composite sealing materials or multi-layer steel (MLS) gaskets, which have become increasingly common over the last few years and are today considered state of the art. Goetze Payen GmbH in Herdorf, Germany, a subsidiary of international automotive supplier T and N, has now developed an innovative new SLS cylinder head gasket consisting of a single layer of steel with a sintered stopper. This new type of gasket reduces the component`s complexity and at the same time provides much greater design flexibility. (orig.) [Deutsch] Seit Asbestfasern zumindest in Europa nicht mehr als Bestandteil von Zylinderkopfdichtungen zugelassen sind, haben Motorenentwickler im wesentlichen zwei Optionen: Sie koennen zum einen auf moderne Weichstoffdichtungen, zum anderen auf die seit einigen Jahren zunehmend gebraeuchlichen Mehrlagen-Stahl-Dichtungen zugreifen. Letztere gelten heute als Stand der Technik. Die Goetze Payen GmbH in Herdorf hat eine neuartige Zylinderkopfdichtung entwickelt, die nur noch aus einer einzigen Lage Stahl mit aufgesinterter Stopperschicht besteht. Dieser neue Dichtungstyp reduziert die Komplexitaet der Komponente und bringt gleichzeitig wesentlich mehr Gestaltungsfreiheit mit sich. (orig.)

  15. Experimental Evaluation of the Surface Alteration of Gasket Samples under Operative Conditions

    M.C. Bignozzi

    2015-12-01

    Full Text Available This paper investigates the surface alteration of gasket samples commercialized by two alternative producers. These gaskets, in polymeric materials, are installed in process plants used for cleaning tires molds by a pioneering ultrasonic process. They are exposed to a combination of ultrasonic waves, temperature, humidity and acid attack causing several erosion phenomena. Their surface degradation under ordinary operative conditions was investigated using mechanical and tribological tests. The experimental characterization was performed by optical microscopy, scanning electron microscopy, thermograms, differential scanning calorimetry curves and infrared spectra aiming at defining the specific mechanics of wearing. As a conclusion, it was possible to state that even if samples exhibit similar chemical structures, their thermal and mechanical properties as well as their geometric dimensions are different. Such differences in the materials might cause various unexpected wear behaviors when gaskets are employed in the same working conditions.


  16. On the Local-Global Conjecture for integral Apollonian gaskets

    Bourgain, Jean; Kontorovich, Alex

    2012-01-01

    We prove that a set of density one satisfies the local-global conjecture for integral Apollonian gaskets. That is, for a fixed integral, primitive Apollonian gasket, almost every (in the sense of density) admissible (passing local obstructions) integer is the curvature of some circle in the gasket.

  17. Robust and Soft Elastomeric Electronics Tolerant to Our Daily Lives.

    Sekiguchi, Atsuko; Tanaka, Fumiaki; Saito, Takeshi; Kuwahara, Yuki; Sakurai, Shunsuke; Futaba, Don N; Yamada, Takeo; Hata, Kenji

    2015-09-01

    Clothes represent a unique textile, as they simultaneously provide robustness against our daily activities and comfort (i.e., softness). For electronic devices to be fully integrated into clothes, the devices themselves must be as robust and soft as the clothes themselves. However, to date, no electronic device has ever possessed these properties, because all contain components fabricated from brittle materials, such as metals. Here, we demonstrate robust and soft elastomeric devices where every component possesses elastomeric characteristics with two types of single-walled carbon nanotubes added to provide the necessary electronic properties. Our elastomeric field effect transistors could tolerate every punishment our clothes experience, such as being stretched (elasticity: ∼ 110%), bent, compressed (>4.0 MPa, by a car and heels), impacted (>6.26 kg m/s, by a hammer), and laundered. Our electronic device provides a novel design principle for electronics and wide range applications even in research fields where devices cannot be used. PMID:26218988

  18. Elastomeric Cellular Structure Enhanced by Compressible Liquid Filler

    Sun, Yueting; Xu, Xiaoqing; Xu, Chengliang; Qiao, Yu; Li, Yibing

    2016-05-01

    Elastomeric cellular structures provide a promising solution for energy absorption. Their flexible and resilient nature is particularly relevant to protection of human bodies. Herein we develop an elastomeric cellular structure filled with nanoporous material functionalized (NMF) liquid. Due to the nanoscale infiltration in NMF liquid and its interaction with cell walls, the cellular structure has a much enhanced mechanical performance, in terms of loading capacity and energy absorption density. Moreover, it is validated that the structure is highly compressible and self-restoring. Its hyper-viscoelastic characteristics are elucidated.

  19. Elastomeric Cellular Structure Enhanced by Compressible Liquid Filler

    Sun, Yueting; Xu, Xiaoqing; Xu, Chengliang; Qiao, Yu; Li, Yibing

    2016-01-01

    Elastomeric cellular structures provide a promising solution for energy absorption. Their flexible and resilient nature is particularly relevant to protection of human bodies. Herein we develop an elastomeric cellular structure filled with nanoporous material functionalized (NMF) liquid. Due to the nanoscale infiltration in NMF liquid and its interaction with cell walls, the cellular structure has a much enhanced mechanical performance, in terms of loading capacity and energy absorption density. Moreover, it is validated that the structure is highly compressible and self-restoring. Its hyper-viscoelastic characteristics are elucidated. PMID:27221079

  20. Liquid-Oxygen-Compatible Cement for Gaskets

    Elmore, N. L.; Neale, B. C.

    1984-01-01

    Fluorelastomer and metal bonded reliably by new procedure. To cure fluoroelastomer cement, metal plate/gasket assembly placed in vacuum bag evacuated to minimum vacuum of 27 inches (69 cm) of mercury. Vacuum maintained throughout heating process and until assembly returns to ambient room temperature. Used to seal gaskets and O-rings or used to splice layers of elastomer to form non-standard sized O-rings. Another possible use is to apply protective, liquid-oxygen-compatible coating to metal parts.

  1. The Hausdorff dimension of the CLE gasket

    Miller, Jason; Wilson, David B

    2012-01-01

    The conformal loop ensemble CLE_kappa is the canonical conformally invariant probability measure on non-crossing loops in a proper simply connected domain in the complex plane. The parameter kappa varies between 8/3 and 8; CLE_{8/3} is empty while CLE_8 is a single space-filling loop. In this work we study the geometry of the CLE gasket, the set of points not surrounded by any loop of the CLE. We show that the almost sure Hausdorff dimension of the gasket is bounded from below by 2-(8-kappa)(3 kappa-8)/(32 kappa) when 4gasket dimension for all values of kappa for which it is defined. The dimension agrees with the prediction of Duplantier-Saleur (1989) for the FK gasket.

  2. Gasketed plate type heat exchanger design software

    Gebremariam, Aklilu

    2016-01-01

    The purpose of this thesis was to make the design of gasketed plate type heat exchangers easier, simple, and accurate by reducing human error. Properly designed heat exchangers can provide more benefits and better safety in wide range of applications. Since the design of heat exchangers is so complicated and involves several steps, computer-aided design has come to be widely used. In this design, along with the knowledge of heat exchangers, the Visual Studio 2013 Professional and the programm...

  3. Lateral Response Comparison of Unbonded Elastomeric Bearings Reinforced with Carbon Fiber Mesh and Steel

    Ali Karimzadeh Naghshineh; Ugurhan Akyuz; Alp Caner

    2015-01-01

    The vertical and horizontal stiffness used in design of bearings have been established in the last few decades. At the meantime, applicability of the theoretical approach developed to estimate vertical stiffness of the fiber-reinforced bearings has been verified in different academic studies. The suitability of conventional horizontal stiffness equation developed for elastomeric material, mainly for steel-reinforced elastomeric bearings, has not been tested in detail for use of fiber-reinf...

  4. 'Tuning' the variable stiffness head gasket: An interactive computational approach

    Glander, D.W.; Punch, E.F.

    1987-01-01

    Problems of bore distortion, combustion blowby and gasket fatigue in lightweight engine blocks are ultimately related to the gasket sealing pressure distribution. For both conventional embossed steel gaskets and composite ones this distribution can be modified by suitable local changes in gasket stiffness. Current methods of gasket optimization concentrate on large scale iterative finite element analysis of the head/gasket/block system, with major computational costs. This paper presents a more economical alternative in which condensed compliance matrices are obtained either from elementary NASTRAN runs or by experimental means. The algorithm enables the gasket engineer to 'tune' the gasket to the desired sealing pressure profile with acceptable stiffness variations.

  5. Gasket sealing performance simulation during cycling operation condition

    The Steam Generators used in CANDU Nuclear Power Plants employ a primary-side obround manway design with two cover plates on each side of the opening. The sealing action against the high pressure primary side fluid is achieved by a spiral wound gasket installed in a groove in both inner and outer cover. The inner cover gasket will be initially pre stressed by the stud preload and by the internal pressure. The gasket in the outer cover will be initially pre stressed with the stud preload and unloaded during the application of the internal pressure. During the start up and shut down of the unit the temperature of the metal parts will change. This change in metal temperature has a significant effect on the gasket contact pressure and hence leak tightness. Because of the double gasket design, evaluation of the gasket pressure and hence leak tightness is only possible by using Finite Element (FE) analysis. This paper will investigate on a generic CANDU type primary manway the change in gasket contact pressure during the transient operation of the unit (heat up, start up, normal operation, shut down and cooled down) that will include the complex interaction between the manway components. The effect of repeated transient operation on the gasket contact pressure will also be investigated. During transient operation of the units (heat up, start up, operation, shut down and cool down) a complex interaction between the manway components occurs, which not only causes time-varying gasket contact pressure but also induces a non-uniform gasket contact pressure along the gasket width. As a result, the leak tightness of the joint may be affected. The effect of different stud preloads on the gasket contact pressure during transient operation is investigated by the 3D FE Analysis of a primary-side obround manway of CANDU's steam generator. The results are used to justify the seal performance of the manway structure under conditions of different stud pretension loads. The distribution

  6. Evaluation of Fillers Dispersion Degree in Elastomeric Magnetic Composites

    Ján Kruželák

    2012-01-01

    Full Text Available Elastomeric magnetic composites were prepared by incorporation of strontium ferrite into polymer matrices based on natural as well as butadiene rubber. Besides the rubber and ferrite, or the combinations of ferrite and carbon black (in case of natural rubber, the model rubber compounds contained only ingredients which support curing process. The study was dedicated to the observation of fillers dispersion degree in the rubber matrices and investigation of physical-mechanical and magnetic properties of prepared composites. The results indicate that the dispersion degree of ferrite in the rubber matrices is not very high, but it can be positively influenced by the addition of carbon black. Despite of the fact that ferrite exhibits only low reinforcing effect on cross-linked elastomeric materials, physical-mechanical properties can be also positively influenced by the mutual change in combinations of both fillers (ferrite and carbon black. The prepared materials seem to have suitable magnetic and elastic properties.

  7. Periferic intravenous infusion of fenoldopam through an elastomeric pump

    Quaranta, T; Cornaggia, G; Turi, S; Mizzi, A; Zangrillo, A

    2009-01-01

    Introduction Fenoldopam has been used to protect renal function in critically ill patients and in those undergoing major surgery, where a possible damage of kidney is expected. Numerous randomized studies and meta-analysis demonstrated the efficacy of fenoldopam in this setting. We performed this study to demonstrate the feasibility of administering fenoldopam, trough an elastomeric pump connected to a peripheral vein, to patients undergoing nephron sparing surgery. Materials and Methods Twen...

  8. Optimization problems on the Sierpinski gasket

    Marek Galewski

    2016-04-01

    Full Text Available We investigate the existence of an optimal process for such an optimal control problem in which the dynamics is given by the Dirichlet problem driven by weak Laplacian on the Sierpinski gasket. To accomplish this task using a direct variational approach with no global growth conditions on the nonlinear term, we consider the existence of solutions, their uniqueness and their dependence on a functional parameter for mentioned Dirichlet problem. This allows us to prove that the optimal control problem admits at least one solution.

  9. Energy dissipation in elastomeric isolators subjected to seismic forces

    Terhune, J.H.; Karim-Panahi, K. [GE Nuclear Energy, San Jose, CA (United States)

    1996-06-01

    In this paper, a detailed analysis is presented to elucidate thermal effects in elastomeric seismic isolators. Using the material properties of elastomers and the time history of typical seismic events, it is shown that a properly designed base structure provides effective heat transfer and limits temperature rise in the elastomer. The frequency-dependent material properties are a key factor in designing the base structure for maximum effectiveness. When thermal effects are considered, the material properties of the elastomer(s) do not change with temperature. Thus, the isolator material do not degrade during a prolonged seismic event and effectiveness is thereby optimized.

  10. Energy dissipation in elastomeric isolators subjected to seismic forces

    In this paper, a detailed analysis is presented to elucidate thermal effects in elastomeric seismic isolators. Using the material properties of elastomers and the time history of typical seismic events, it is shown that a properly designed base structure provides effective heat transfer and limits temperature rise in the elastomer. The frequency-dependent material properties are a key factor in designing the base structure for maximum effectiveness. When thermal effects are considered, the material properties of the elastomer(s) do not change with temperature. Thus, the isolator material do not degrade during a prolonged seismic event and effectiveness is thereby optimized

  11. A Grain of Dust Falling Through a Sierpinski Gasket

    Samantha LEORATO; Enzo ORSINGHER

    2007-01-01

    In this paper we analyze the downward random motion of a particle in a vertical,bounded,Sierpinski gasket G,where at each layer either absorption or delays are considered.In the case of motion with absorption the explicit distribution of the position of the descending particle in the pre-gasket Gn is obtained and the limiting case of the Sierpinski gasket discussed.For the delayed downward motion we derive a representation of the random time needed to arrive at the base of Gn in terms of independent binomial random variables (containing the contribution of delays at di .erent layers with di .erent geometrical structures).

  12. Contracting Similarity Fixed Point of General Sierpinski Gasket

    Shanhui Sun

    2013-12-01

    Full Text Available The article mainly studies the contracting similarity fixed point and the structure of the general Sierpinski gasket. Firstly, the paper analyzes the importance of contracting similarity fixed point in fractal geometry. Based on a series of definitions, the article studies the contracting similarity fixed point. Then, the paper researches on the structure of the general Sierpinski gasket, and describes it through function. Using a new characteristic function and other techniques, the article gives two important lemmas of the general Sierpinski gasket and the complete proof. By the proved lemmas, the article gets the formula of the contracting similarity fixed point of the Sierpinski gasket, and then proves that the aforementioned contracting similarity fixed points form a new fractal. As application, the paper classifies the above contracting similarity fixed points into three types and gives two examples.

  13. REVIEW OF ENERGY EFFICIENCY OF REFRIGERATOR/FREEZER GASKETS

    The report gives results of an investigation of the significance of heat leakage through gaskets in household refrigerator/freezers, explores different design features, and suggests further study if necessary. The report gives results of an extensive literature review, interviews...

  14. Chemical Stability of Telavancin in Elastomeric Pumps☆

    Sand, Patrick; Aladeen, Traci; Kirkegaard, Paul; LaChance, Dennis; Slover, Christine

    2015-01-01

    solutions examined. All decreases in telavancin concentration were ≤2.7%. Comparison of each test sample solution to the corresponding glass control indicated no loss of active drug due to absorption by the elastomeric material of the pumps. The greatest increase in the amount of total degradants observed over the 8-day period was ~0.7 w/w%. Conclusions The results of this study indicate that telavancin remains chemically stable when diluted in the Intermate Infusion System and the Homepump Eclipse elastomeric pumps and stored at 2°C to 8°C for up to 8 days protected from light at the concentration range and dilution schemes evaluated. PMID:26649079

  15. Embedded Strain Gauges for Condition Monitoring of Silicone Gaskets

    Timo Schotzko; Walter Lang

    2014-01-01

    A miniaturized strain gauge with a thickness of 5 µm is molded into a silicone O-ring. This is a first step toward embedding sensors in gaskets for structural health monitoring. The signal of the integrated sensor exhibits a linear correlation with the contact pressure of the O-ring. This affords the opportunity to monitor the gasket condition during installation. Thus, damages caused by faulty assembly can be detected instantly, and early failures, with their associated consequences, can be ...

  16. Identification of Swelling cause on Rubber Gaskets

    Fagerland, Jenny

    2011-01-01

    The aim of this master thesis was to develop an analysis method which identifies the swelling cause of EPDM rubber gaskets. The method shall facilitate failure investigation of rubber gaskets used in plate heat exchangers which require both determinations of volatile and involatile compounds as well as polar and non-polar compounds. To achieve this goal a combination analysis method of Headspace Gas chromatography Mass spectrometry (GC-MS) and liquid-liquid extraction Fourier Transform Infrar...

  17. An in-vitro study to compare the force degradation of pigmented and non-pigmented elastomeric chains

    Palathottungal Joseph Antony; Joby Paulose

    2014-01-01

    Aim: The purpose of the study was to compare the force delivery and force decay property of pigmented and non-pigmented elastomeric chains, widely used in orthodontic practice. Materials and Methods: Force delivered by the samples consisting of pigmented and non-pigmented elastomeric chains obtained from 3 manufacturers were tested at 3 time intervals (as received, after 24 hours and 21 days of stretching) to measure the force delivered by the test samples, as well as the force decay over...

  18. Magnetoactive elastomeric composites: Cure, tensile, electrical and magnetic properties

    K Sasikumar; G Suresh; K A Thomas; Reji John; V Natarajan; T Mukundan; R M R Vishnubhatla

    2006-11-01

    Magnetically active elastomer materials were prepared by incorporating nickel powder in synthetic elastomeric matrices, polychloroprene and nitrile rubber. Cure characteristics, mechanical, electrical and magnetic properties were experimentally determined for different volume fractions of magnetoactive filler. The cure time decreases sharply for initial filler loading and the decrease is marginal for additional loading of filler. The tensile strength and modulus at 100% strain was found to increase with increase in the volume fraction of nickel due to reinforcement action. The magnetic impedance and a.c. conductivity are found to increase with increase in volume fraction of nickel as well as frequency.

  19. SEALING PERFORMANCE OF GASKETED FLANGE JOINTS – A PARAMETRIC STUDY

    Muhammad Abid

    2014-12-01

    Full Text Available ABSTRACT: This paper aims at finding the leak rate through ANSI class#150 flange joints using compressed asbestos sheet gasket under combined structural and thermal transient loading conditions. The solution is obtained using two different leak rate models and two different bolt up values. The gasket compressive strain based model employs strains that are determined using finite element analysis. The other model is based on the porous media theory in which gasket is considered as porous media. Leak rates determined using these leak rate models are compared for different tightness classes and discussed. ABSTRAK: Kajian bertujuan mencari kadar bocor menerusi sambungan bebibir kelas ANSI#150 menggunakan gasket kepingan asbestos termampat di bawah kondisi bebanan gabungan struktur dan terma fana. Solusinya diperolehi dengan menggunakan dua model kadar bocor yang berbeza dan dua nilai atas bolt yang berlainan. Model terikan berasaskan pemampat gasket menggunakan terikan yang ditentukan dengan analisis unsur terhingga. Model yang lainnya berasaskan teori bahantara berongga di mana gasket digunakan sebagai medium. Kadar bocor ditentukan dengan menggunakan model kadar bocor, yang kemudiannya dibandingkan pada kelas keketatan yang berbeza dan keputusannya dibincangkan.KEYWORDS: bolted flange; gasket; leak rate; finite element analysis; tightness class compressive strains; porous media Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";}

  20. Coevolutionary extremal dynamics on gasket fractal

    Lee, Kyoung Eun [Department of Physics, Inha University, Incheon 402-751 (Korea, Republic of)] [Computational Physics, IfB, ETH-Honggerberg, Schafmattstrasse 6, 8093 Zurich (Switzerland); Sung, Joo Yup; Cha, Moon-Yong; Maeng, Seong Eun; Bang, Yu Sik [Department of Physics, Inha University, Incheon 402-751 (Korea, Republic of); Lee, Jae Woo, E-mail: jaewlee@inha.ac.k [Department of Physics, Inha University, Incheon 402-751 (Korea, Republic of)

    2009-11-09

    We considered a Bak-Sneppen model on a Sierpinski gasket fractal. We calculated the avalanche size distribution and the distribution of distances between subsequent minimal sites. To observe the temporal correlations of the avalanche, we estimated the return time distribution, the first-return time, and the all-return time distribution. The avalanche size distribution follows the power law, P(s)approxs{sup -tau}, with the exponent tau=1.004(7). The distribution of jumping sites also follows the power law, P(r)approxr{sup -pi}, with the critical exponent pi=4.12(4). We observe the periodic oscillation of the distribution of the jumping distances which originated from the jumps of the level when the minimal site crosses the stage of the fractal. The first-return time distribution shows the power law, P{sub f}(t)approxt{sup -tau}{sub f}, with the critical exponent tau{sub f}=1.418(7). The all-return time distribution is also characterized by the power law, P{sub a}(t)approxt{sup -tau}{sub a}, with the exponent tau{sub a}=0.522(4). The exponents of the return time satisfy the scaling relation tau{sub f}+tau{sub a}=2 for tau{sub f}<=2.

  1. Coevolutionary extremal dynamics on gasket fractal

    Lee, Kyoung Eun; Sung, Joo Yup; Cha, Moon-Yong; Maeng, Seong Eun; Bang, Yu Sik; Lee, Jae Woo

    2009-11-01

    We considered a Bak-Sneppen model on a Sierpinski gasket fractal. We calculated the avalanche size distribution and the distribution of distances between subsequent minimal sites. To observe the temporal correlations of the avalanche, we estimated the return time distribution, the first-return time, and the all-return time distribution. The avalanche size distribution follows the power law, P(s)∼s, with the exponent τ=1.004(7). The distribution of jumping sites also follows the power law, P(r)∼r, with the critical exponent π=4.12(4). We observe the periodic oscillation of the distribution of the jumping distances which originated from the jumps of the level when the minimal site crosses the stage of the fractal. The first-return time distribution shows the power law, P(t)∼t, with the critical exponent τ=1.418(7). The all-return time distribution is also characterized by the power law, P(t)∼t, with the exponent τ=0.522(4). The exponents of the return time satisfy the scaling relation τ+τ=2 for τ⩽2.

  2. Elastomeric PGS scaffolds in arterial tissue engineering.

    Lee, Kee-Won; Wang, Yadong

    2011-01-01

    Cardiovascular disease is one of the leading cause of mortality in the US and especially, coronary artery disease increases with an aging population and increasing obesity. Currently, bypass surgery using autologous vessels, allografts, and synthetic grafts are known as a commonly used for arterial substitutes. However, these grafts have limited applications when an inner diameter of arteries is less than 6 mm due to low availability, thrombotic complications, compliance mismatch, and late intimal hyperplasia. To overcome these limitations, tissue engineering has been successfully applied as a promising alternative to develop small-diameter arterial constructs that are nonthrombogenic, robust, and compliant. Several previous studies have developed small-diameter arterial constructs with tri-lamellar structure, excellent mechanical properties and burst pressure comparable to native arteries. While high tensile strength and burst pressure by increasing collagen production from a rigid material or cell sheet scaffold, these constructs still had low elastin production and compliance, which is a major problem to cause graft failure after implantation. Considering these issues, we hypothesized that an elastometric biomaterial combined with mechanical conditioning would provide elasticity and conduct mechanical signals more efficiently to vascular cells, which increase extracellular matrix production and support cellular orientation. The objective of this report is to introduce a fabrication technique of porous tubular scaffolds and a dynamic mechanical conditioning for applying them to arterial tissue engineering. We used a biodegradable elastomer, poly (glycerol sebacate) (PGS) for fabricating porous tubular scaffolds from the salt fusion method. Adult primary baboon smooth muscle cells (SMCs) were seeded on the lumen of scaffolds, which cultured in our designed pulsatile flow bioreactor for 3 weeks. PGS scaffolds had consistent thickness and randomly distributed macro

  3. Chemical Stability of Telavancin in Elastomeric Pumps

    Patrick Sand, MSc

    2015-12-01

    Conclusions: The results of this study indicate that telavancin remains chemically stable when diluted in the Intermate Infusion System and the Homepump Eclipse elastomeric pumps and stored at 2°C to 8°C for up to 8 days protected from light at the concentration range and dilution schemes evaluated.

  4. Vibration modes of 3n-gaskets and other fractals

    We rigorously study eigenvalues and eigenfunctions (vibration modes) on the class of self-similar symmetric finitely ramified fractals, which include the Sierpinski gasket and other 3n-gaskets. We consider the classical Laplacian on fractals which generalizes the usual one-dimensional second derivative, is the generator of the self-similar diffusion process, and has possible applications as the quantum Hamiltonian. We develop a theoretical matrix analysis, including analysis of singularities, which allows us to compute eigenvalues, eigenfunctions and their multiplicities exactly. We support our theoretical analysis by symbolic and numerical computations. Our analysis, in particular, allows the computation of the spectral zeta function on fractals and the limiting distribution of eigenvalues (i.e., integrated density of states). We consider such examples as the level-3 Sierpinski gasket, a fractal 3-tree, and the diamond fractal

  5. Maximum stress of interlayer steel plates in elastomeric isolator

    Recently, laminated rubber bearings are used in many buildings as isolation devices. This paper presents the results of Finite Element Analysis (FEM) of elastomeric isolators with a diameter of 500 mm, and proposes a prediction method of the maximum stress in the interlayer steel plate. This analysis was focused on the maximum stress of the steel plate while the isolator was deformed in the horizontal direction. The steel plate was modeled as an elasto-plastic material. The elastomeric material was represented by the strain energy density function (Takayama et al., my 1992). The maximum stress in the steel plates increased and exceeded the yield stress as the shear deformation became larger. The total yield area of the steel plates without a central hole was below 10% of the actual plan area, but, in the case of plates with a central hole of 50 mm in diameter, the total yield area was over 20%. The prediction method shows a good correspondence with the FEM results

  6. Finite Element Analysis of the Sealing Properties of Gasket under Specific Load Conditions%特定载荷作用下的垫片密封特性有限元分析

    张雷; 刘俊亨

    2015-01-01

    This paper uses the ANSYS software for finite element analysis of gasket, draws the compression characteristic curve of gasket material, and simulates the compression characteristic of gasket under the specific load conditions. According to the results of simulation, it can verify whether the sealing properties of gasket under specific load conditions can conform to the requirements or not.%利用ANSYS软件,对垫片进行有限元分析,绘制垫片材料的压缩特性曲线,进行特定载荷条件下垫片的压缩特性模拟,根据仿真结果,能够验证特定载荷条件下垫片的密封特性是否符合要求。

  7. SOME GEOMETRIC PROPERTIES OF BROWNIAN MOTION ON SIERPINSKI GASKET

    WUJUN; XIAOYIMIN

    1995-01-01

    Let {X(t),t≥0} be Brownian motion on Sierpinski gasket,The Hausdorff and packing dimensions of the image of a ompact set are studied,The uniform Hausdorff and packing dimensions of the inverse image are also discussed.

  8. 46 CFR 56.30-35 - Gasketed mechanical couplings.

    2010-10-01

    ... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND... section applied to pipe fittings that form a seal by compressing a resilient gasket onto the pipe joint... creeping on the pipe and uncovering the joint. Bite-type devices do not provide positive protection...

  9. ISI of elastomeric components in nuclear reactors

    On irradiation, polymers undergo chemical changes in their back bone/side chain. If the chemical structure is altered, the basic characteristic of parent polymer also changes, hence the property of the component also changes over the period of exposure to any type of radiation. This paper gives an idea about the main properties to be checked for assuring the quality of elastomeric components in view for radiation applications

  10. Practical Usage of Effect of Cold Weldability of Metals in Joint of Plastically Deformable Gasket and Flanges of Detachable Joint of Fuel Pipe-Line

    Danchenko, V. G.

    2002-01-01

    The performed investigations of the character of changing the leakage of control gas through flange connections in the process of drawing- up the bolts in to calculation moment and subsequent lowering of bolt loading to zero have shown the following. Gradual reduction of leakage through a gasket occurs in the process of increasing the tightening torque up to its complete absence. But there is no leakage through the unloaded gasket after untwisting all nuts and removal of fastening bolts from flanges. The performed analysis has shown that this effect is caused by cold weldability of the gasket with flanges; this is a result of flowing of its material into microrough holes of contact surfaces of flanges at plastic deformation with formation of strong and dense contact. Some technological methods of formation of undetachable joint have been developed for practical application of this effect. According to one of those methods, drawing- up the gasket is performed with the help of flanges preliminarily. Those bolts are substituted by less strong standard bolts for drawing- up by less moment after achievement of stress needed. Method of pressurization of the joint is more effective when technological detachable flanges and bolts are used for reduction of the gasket up to its plastic state. Those flanges and bolts are removed after drawing- up; after that standard flanges are loaded by the moment used for reception of effort only from pressure of operational medium in the pipe- line (Qoper.m.) because drawing- up of the gasket by effort (Qeff.) that provides its plastic state, is already achieved. Then we exclude the first component (Qeff.) in dependence which is known from technical literature: Qdraw. = Qeff . + Qoper .m. = qFgas. + PFpip. (1), and the final formula for calculation of the effort of drawing- up the joint (in which drawing- up the gasket with provision of cold weldability is carried out preliminarily before drawing- up the standard bolts) is expressed in

  11. Modelling leaktightness in a sealing system using elastomeric seal

    The container of radioactive gases in a transport cask is governed by the efficiency of the sealing system. The gas release of an elastomeric seal can have two causes: 1) the permeation through the elastomer which is an intrinsic characteristic for the material. 2) the leakage through geometrical defects (cracks, gaps, capillaries...) which are of a random nature. The purpose of this study is to develop representative models of these two leakage processes. In order to validate these models, experimental measurements were performed with a specific equipment ('LISE' test rig), to carry out tests with O-ring in a trapezoidal groove within a temperature range from -50degC to +300degC. The leakage rate was measured with a mass spectrometer using pure gases or gas mixtures. (J.P.N.)

  12. Description of gasket failure in a 7 cell PEMFC stack

    Husar, Attila; Serra, Maria [Institut de Robotica i Informatica Industrial, Parc Tecnologic de Barcelona, Edifici U, C. Llorens i Artigas, 4-6, 2a Planta, 08028 Barcelona (Spain); Kunusch, Cristian [Laboratorio de Electronica Industrial Control e Instrumentacion, Facultad de Ingenieria, UNLP (Argentina)

    2007-06-10

    This article presents the data and the description of a fuel cell stack that failed due to gasket degradation. The fuel cell under study is a 7 cell stack. The unexpected change in several variables such as temperature, pressure and voltage indicated the possible failure of the stack. The stack was monitored over a 6 h period in which data was collected and consequently analyzed to conclude that the fuel cell stack failed due to a crossover leak on the anode inlet port located on the cathode side gasket of cell 2. This stack failure analysis revealed a series of indicators that could be used by a super visional controller in order to initiate a shutdown procedure. (author)

  13. Method of making hollow elastomeric bodies

    Broyles, H. F.; Moacanin, J.; Cuddihy, E. F. (Inventor)

    1976-01-01

    Annular elastomeric bodies having intricate shapes are cast by dipping a heated, rotating mandrel into a solution of the elastomer, permitting the elastomer to creep into sharp recesses, drying the coated mandrel and repeating the operation until the desired thickness has been achieved. A bladder for a heart assist pump in which a cylindrical body terminating in flat, sharp horizontal flanges fabricated by this procedure has been subjected to over 2,500 hours of simulated life conditions with no visible signs of degradation.

  14. Accuracy and consistency of modern elastomeric pumps.

    Weisman, Robyn S; Missair, Andres; Pham, Phung; Gutierrez, Juan F; Gebhard, Ralf E

    2014-01-01

    Continuous peripheral nerve blockade has become a popular method of achieving postoperative analgesia for many surgical procedures. The safety and reliability of infusion pumps are dependent on their flow rate accuracy and consistency. Knowledge of pump rate profiles can help physicians determine which infusion pump is best suited for their clinical applications and specific patient population. Several studies have investigated the accuracy of portable infusion pumps. Using methodology similar to that used by Ilfeld et al, we investigated the accuracy and consistency of several current elastomeric pumps. PMID:25140510

  15. 节能门封%Energy Efficient Gasket

    2012-01-01

    The improvement of refrigerator gasket can achieve the energy consumption from convection, heat conduction and radiation. As the result of many research and experiments, the improvement of gasket structure can achieve 2% ~4%energy consumption of refrigerator. The article also previews the direction and trend of gasket development.%  本文总结了冰箱门封结构及材料优化可节省能量消耗,着重从对流、热传导和辐射3个方向来优化门封设计,经过大量的研究和试验分析得出,通过对冰箱门封结构的优化设计可以实现降低冰箱能耗2%~4%,并就未来门封的发展趋势和发展方向作出了展望。

  16. Development of radiation resistant EPDM based rubber compound for gasket application

    The elastomer material selected for seals for applications in reprocessing plant is required to possess both radiation and chemical resistance. Ethylene propylene diene monomer (EPDM) is used for gasket application in chemical industries due to its excellent resistance to heat, oxidation, ozone and weather ageing. To ascertain the suitability of EPDM for applications in radioactive environment, EPDM rubber compound was developed and its radiation tolerance has been evaluated by exposing to gamma radiation and measuring the change in the mechanical properties. EPDM rubber, ZnO, MgO, carbon black, aromatic oil, ethylene thiourea and stearic acid were the materials used for the development of rubber compound. Mixing was done as per ASTM D-3182 practice in a laboratory two-roll mill using the mixing cycle for the required formulation. Test slabs and buttons of the mixed compounds were obtained by compression-moulding technique as per ASTM D-3192 procedure and according to the optimum cure time got from Rheometric studies. The rubber compound was sheeted out to an uniform thickness of 2 mm and the product moulding was carried out in a hydraulic compression moulding press at 155℃ for a curing time of 20 min. The mechanical properties of the rubber compound were determined and were exposed to gamma radiation at the dose of 105, 106, 107 and 108 rads to understand the effect of radiation on the rubber compound. The mechanical properties measured for the rubber compound were 41 MPa as tensile strength, 550% as elongation at break, 39% as compression set and 67 as shore A hardness. These properties degraded with radiation. Degradation is due to the formation of radicals by radiation and subsequent chain scission and crosslinking. Increase in hardness by 11 points was observed after exposure to 108 rads. Tensile strength decreased to 61% and elongation at break decreased to 57% after 108 rads. Compression set, which is the important property of a gasket material was found

  17. Sensitivity improvement of a fibre Bragg grating pH sensor with elastomeric coating

    A new optical pH sensor based on fibre Bragg grating (FBG) is demonstrated. The sensor consists of a FBG coated with pH sensitive hydrogel. The sensing was performed through the detection of wavelength shifts resulting from the induced strain on the FBG due to mechanical expansion of the hydrogel. An elastomeric coating was applied before the hydrogel coating to improve the sensitivity. The sensor performance was investigated by simulating the hydrogel swelling and the strain induced on the FBG. The swelling of hydrogel due to pH change was modelled using a free-energy function and was solved using the finite element method. With silicone rubber as the elastomer material, the results show that the sensitivity was improved by up to 66% compared to that of the FBG pH sensor without elastomeric coating

  18. NCO-5 Technician Cuts Finger while Cutting Gasket Material

    Trujillo, Stanley [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schreiber, Stephen Bruce [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mcneel, John Worth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Monsalve-Jones, Robert A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Welsh, Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ortega, Greg N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez, Xavier Baltazar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Padilla, Ruby A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-10

    As part of the ADPSM Safety Improvement Plan, the WSST has established a subcommittee for a Learning Team. The purpose of a Learning Team is to transfer and communicate the information into operational feedback and improvement. We want to pay attention to the small things that go wrong because they are often early warning signals and may provide insight into the health of the whole system.

  19. 缠绕垫片外环发生翘曲的原因分析%Analysis on the Outer Ring Bending of Spiral Wound Gasket

    由立臣; 任大美; 郑康宁

    2011-01-01

    The force model of the spiral wound gasket outer ring when the V-type groove is asymmetric was establish,the force analysis and the calculation of strength under the bending moment were carried out. The theoretical calculation proves that there is a moment in the spiral wound gasket outer ring when the V-type groove is asymmetric, which makes the spiral wound gasket outer ring bend. Consequently, this bend diminishes the spring back effect to the body of the spiral wound gasket, influences the sealing performance, and it is the main factor which leads the leakage of spiral wound gasket. To fig-ure up the critical moment, the critical offset value and the maximum deflexion under the critical moment according to the material allowable stress, the spiral wound gasket outer ring bend can be prevented. It is a guidance on the production of the spiral wound gasket and drafting the standards.%建立缠绕垫片外环V型槽不对称情况下外环的受力模型,并进行受力分析和弯矩作用下的强度计算.通过理论计算,证明缠绕垫片外环V型槽不对称时,存在一个弯矩,使缠绕垫片外环发生翘曲,从而减小对缠绕垫片本体的回弹作用,影响缠绕垫片的密封性能,这是外环翘曲缠绕垫片容易产生泄漏的主要原因;根据材料的许用应力求出临界弯矩和临界偏移量,以及在临界弯矩下外环的最大挠度,从而可防止外环发生翘曲变形,对缠绕垫片的生产、标准制定具有指导意义.

  20. PERL - European research project on characterization of gaskets for bolted flange connections

    Great progress was observed in the European standardization in the last years in the field of the design of floating type bolted flange connections. New design rules were developed (EN 1591) which include new definitions of gasket characteristics for the calculation of floating type flanged joints. In addition a new gasket testing standard was drafted (prEN 13555) which assures a comprehensive characterization of gaskets for bolted flanged joints. This draft standard contains some new features which were examined and validated within the European research project PERL (Pressure Equipment - Reduction of Leak Rate). The gasket testing strategy laid down in prEN 13555 is presented in this paper. Some testing results highlighten the measuring procedures and the evaluation of the gasket characteristics. (orig.)

  1. Study of dynamic response of piping system with gasketed flanged joints using finite element analysis

    The dynamic response of piping system with gasketed flanged joints at various temperatures is studied using finite element analysis. FE simulation with thermo-mechanical analysis is performed, followed by modal and harmonic analysis. Important parameters affecting the vibration are discussed. Temperature of internal fluid induces thermal stresses which influence the natural frequencies significantly. A comparison has been made between metal gasket and spiral wound gasket. Results show that the natural frequencies corresponding to particular modes are influenced by the type of gasket used. - Highlights: ► We examine dynamic response of piping system at various temperatures. ► Thermo-mechanical analysis is performed followed by modal and harmonic analysis. ► The temperature of internal fluid influences the natural frequencies significantly. ► Natural frequencies and modes are also influenced by type of gasket used. ► Natural frequency is varied by12.3% for first bending mode shape.

  2. Stability of colistimethate sodium in a disposable elastomeric infusion device.

    Abdulla, Alan; van Leeuwen, Roelof W F; de Vries Schultink, Aurelia H M; Koch, Birgit C P

    2015-01-01

    Infections of the respiratory tract with Pseudomonas aeruginosa in cystic fibrosis patients are frequently treated with colistimethate sodium (CMS). For the intravenous administration of CMS a disposable elastomeric pump is a convenient option. To date, there are no data available on the chemical stability of CMS solutions stored in elastomeric pumps. We evaluated the chemical stability of 0.8 mg/mL solutions of CMS by measuring the degradation over a period of 7 days. Test samples were prepared by diluting CMS with saline solution (0.9%). The preparations were transferred to 100-mL elastomeric pumps and stored at 4 °C. The chemical stability was measured by a high-performance liquid chromatography method with UV detection. There was no degradation of CMS (elastomeric pump. PMID:25863116

  3. The effect of dietary pigmentation on the esthetic appearance of clear orthodontic elastomeric modules

    Talic, Nabeel F; Almudhi, Abdullazez A

    2016-01-01

    Objective: To compare the stain resistance of three types of clear elastomeric modules exposed to several common dietary substances through the assessment of the perception of a group of dentists to discoloration using visual analog scale (VAS). Materials and Methods: Elastomeric modules from Unitek (AU), Ormco (OR), and dentaurum (DE) were immersed in the following food substances: Coffee, black tea, chocolate, energy drink, ketchup, and Coca-Cola for 72 h. VAS was used to reflect the module staining severity. Results: Significant difference was found among the three types of modules examined in this study. OR modules showed the least mean staining ratings by the examiners. There was no statistical difference in the staining properties between AU and DE modules. Coffee and tea showed higher staining potential as compared to all staining media. Furthermore, there was no difference in the staining characteristics of coffee and black tea. Conclusions: Coffee and tea are strong staining media that should be avoided by patients who opted to have esthetic appliances for their orthodontic treatment. Elastomeric modules manufactured by AU showed higher staining optical properties as compared to the other two companies, which could be related to the manufacturing processing of these modules. PMID:27127754

  4. The application of elastomeric connector for multi-channel electrophysiological recordings.

    Szabó, Imre; Máthé, Kálmán; Tóth, Attila; Hernádi, István; Czurkó, András

    2002-02-15

    Interest in recording multi-channel electrophysiological data from behaving animals is rapidly growing, and many laboratories tend to record a large number of EEG and/or multi-unit channels, despite the limitation of the size of the headpiece that a small behaving animal can carry. A common drawback of these experiments, therefore, is the relatively large size of even the smallest, commercially available, high-density micro-connectors for the headset. To overcome this problem, we suggest the application of elastomeric or silicone inter-rubber connectors, that are widely used in electronics. The elastomeric or "zebra" connector consists of alternating thin strips of layered electrically conductive and non-conductive materials. The conductive strips provide electrical connections between uninsulated contact surfaces of printed circuit boards such as the connector plate of the micro-drive, that holds the brain electrode wires, and the preamplifier board of the recording system. In the present paper, we provide technical details of the design of this type of connector-sets and discuss common issues arising from their use. By comparing the applicability of two designs, we aim to demonstrate the simplicity, reliability and durability of the elastomeric inter-rubber connectors in electrophysiological experiments on freely moving laboratory animals. PMID:11850041

  5. Hybrid magnetorheological fluid–elastomeric lag dampers for helicopter stability augmentation

    A laboratory demonstration of a hybrid magnetorheological fluid–elastomeric (MRFE) damper is investigated for adjustable or programmable lag mode damping in helicopters, so that damping requirements can be varied as a function of different flight conditions. The laboratory demonstration of this hybrid MRFE lag damper consists of a double lap shear elastomeric damper in parallel with two magnetorheological (MR) flow mode dampers. This is compared to a damper where only elastomeric materials are implemented, i.e., a double lap shear specimen. The relationship between the output force and the quasi-steady harmonic displacement input to a flow mode MR damper is exploited, where the output force can be adjusted as a function of applied magnetic field. Equivalent viscous damping is used to compare the damping characteristics of the hybrid damper to a conventional elastomeric damper under steady-state sinusoidal displacement excitation. To demonstrate feasibility, a hybrid MRFE damper test setup is designed, and single frequency (lag frequency or rotor in-plane bending frequency) and dual frequency (lag frequency and rotor frequency) tests are conducted under different magnetic fields. The hybrid MRFE damper exhibits amplitude-dependent damping behavior. However, with application of a magnetic field, the damping level is controlled to a specific damping level objective as a function of displacement amplitude. Similarly, under dual frequency conditions, damping degradation at the lag frequency, because of lag motion at the rotor frequency, can also be recovered by increasing magnetic field. A time-domain analysis is developed to study the nonlinear dynamic behavior of the hybrid MRFE damper. Using rate-dependent elasto-slides, the amplitude-dependent behavior of the hybrid MRFE damper is accurately reconstructed using both constant and current-dependent (i.e. controllable) parameters. The analysis is physically motivated and can be applied to the elastomer and MR fluid

  6. Solvent-resistant elastomeric microfluidic devices and applications

    van Dam, Robert Michael

    Microfluidics is increasingly being used in many areas of biotechnology and chemistry to achieve reduced reagent volumes, improved performance, integration, and parallelism, among other advantages. Though early devices were based on rigid materials such as glass and silicon, elastomeric materials such as polydiznethylsiloxane (PDMS) are rapidly emerging as a ubiquitous platform for applications in biotechnology. This is due, in part, to simpler fabrication procedures and to the ability to integrate mechanical microvalves at vastly greater densities. For many applications in the areas of chemical synthesis and analysis, however, PDMS cannot replace glass and silicon due to its incompatibility with many solvents and reagents. Such areas could benefit tremendously from the development of an elastomeric microfluidic device technology that combines the advantages of PDMS with the property of solvent resistance. Simplified fabrication could increase the accessibility of microfluidics, and the possibility of dense valve integration could lead to significant advances in device sophistication. Applications could be more rapidly developed by design re-use due to the independence of mechanical valves on fluid properties (unlike electrokinetic pumping), and the property of permeability could enable novel fluidic functions for accessing a broader range of reactions than is possible in glass and silicon. The first half of this thesis describes our strategies and efforts to develop this new enabling technology. Several approaches are presented in Chapter 3, and two particularly successful ones, based on new elastomers (FNB and PFPE), are described in Chapters 4 and 5. Chapter 6 describes a novel method of fabricating devices from 3D molds that could expand the range of useful clastomers. The second half of this thesis discusses microfluidic combinatorial synthesis and high throughput screening-applications that take particular advantage of the ability to integrate thousands of

  7. Plaque accumulation and Streptococcus mutans levels around self-ligating bracket clips and elastomeric modules: A randomized controlled trial

    Dhaval Fadia

    2015-01-01

    Full Text Available Aim: To determine the effect of two different ligating systems that is, elastomeric modules and self-ligating (SL bracket systems (Smartclip - 3M Unitek with respect to harboring bacterial plaque in fixed orthodontic treatment. Objectives: To assess, evaluate, and compare the amount of plaque accumulation and Streptococcus mutans colonization around elastomeric ligation and SL clips in the smart clip appliance. Materials and Methods: A total of 111 orthodontic patients scheduled for fixed orthodontic treatments were selected for this split maxillary arch study. All the patients were bonded with smart-clip (3M Unitek SL brackets, and the wire was placed into the bracket slots, on the randomly selected hemi arch, elastomeric modules were placed for the study to be conducted. Microbial and periodontal plaque accumulation was recorded at 3-time intervals post ligation. Plaque index-by Silness and Loe, modified Quigely Hein index, bleeding on probing were evaluated, and biofilm was collected from the tooth surface after 30 days and placed in petri dishes containing Mitis Salivarius agar for bacterial culturing. Result: It was observed that the side where ligation was done with elastomeric modules accumulated more plaque and increase in S. mutans colony forming units as compared to the side without external ligation (P < 0.05. Conclusion: Reduced bacterial colonization and better plaque control was seen with SL orthodontic bracket appliance system as compared to conventional ligation method.

  8. An in-vitro study to compare the force degradation of pigmented and non-pigmented elastomeric chains

    Palathottungal Joseph Antony

    2014-01-01

    Full Text Available Aim: The purpose of the study was to compare the force delivery and force decay property of pigmented and non-pigmented elastomeric chains, widely used in orthodontic practice. Materials and Methods: Force delivered by the samples consisting of pigmented and non-pigmented elastomeric chains obtained from 3 manufacturers were tested at 3 time intervals (as received, after 24 hours and 21 days of stretching to measure the force delivered by the test samples, as well as the force decay over time. Results: The force delivered by the non-pigmented samples was significantly greater than the pigmented ones at all 3 time intervals irrespective of the brand. Force decay was more significant in case of pigmented samples. Force decay was greater noticed in first 24 hours of testing and a gradual decrease in force was observed from 24 hours to 21 days in all test samples irrespective of the brand or color. Conclusion: Non-pigmented elastomeric chains exhibited better force delivery and less force decay percentage when compared to pigmented chains. Though colored elastomeric chains are widely used in present day orthodontic practice to satisfy the younger age group patients, the study ascertains the prudential use of pigmented and non-pigmented chains for efficient and faster orthodontic treatment.

  9. Charge Effects on Mechanical Properties of Elastomeric Proteins

    Kappiyoor, Ravi; Balasubramanian, Ganesh; Dudek, Daniel; Puri, Ishwar

    2012-02-01

    Several biological molecules of nanoscale dimensions, such as elastin and resilin, are capable of performing diverse tasks with minimal energy loss. These molecules are efficient in that the ratio of energy output to energy consumed is very close to unity. This is in stark contrast to some of the best synthetic materials that have been created. For example, it is known that resilin found in dragonflies has a hysteresis loss of only 0.8% of the energy input while the best synthetic rubber made to date, polybutadiene, has a loss of roughly 20%.We simulate tensile tests of naturally occurring motifs found in resilin (a highly hydrophilic protein), as well as similar simulations found in reduced-polarity counterparts (i.e. the same motif with the charge on each individual atom set to half the natural value, the same motif with the charge on each individual atom set to zero, and a motif in which all the polar amino acids have been replaced with nonpolar amino acids). The results show a strong correlation between charge and extensibility. In order to further understand the effect of properties such as charge on the system, we will run simulations of elastomeric proteins such as resilin in different solvents.

  10. A NEW LOWER BOUND OF THE HAUSDORFF MEASURE OF THE SIERPINSKI GASKET

    Zhiwei Zhu; Zuoling Zhou; Baoguo Jia

    2006-01-01

    For the Sierpinski gasket, by using a sort of cover consisting of special regular hexagons, we define a new measure that is equivalent to the Hausdorff measure and obtain a lower bound of this measure. Moreover, the following lower bound of the Hausdroff measure of the Sierpinski gasket has been achieved Hs(S) ≥ 0.670432,where S denotes the Sierpinski gasket, s = dimH(S) = log23, and Hs(S) denotes the s-dimensional Hausdorff measure of S. The above result improves that developed in [2].

  11. Elastomeric composites with tuned electromagnetic characteristics

    This paper presents a novel elastomeric composite that exhibits a deformation-induced change in chirality. Previous efforts primarily dealt with a coil array in air without chiral tuning. Here, a composite is created that consists of an array of parallel, metallic helices of the same handedness embedded in a polymer matrix. The chiral response of the composite depends on pitch, coil diameter, wire thickness and coil spacing; however, pitch has the greatest effect on electromagnetic performance. The present study explores this effect by using helical elements to construct a chiral medium that can be mechanically stretched to adjust pitch. This adjustment directly affects the overall chirality of the composite. A prototype sample of the composite, fabricated for operation between 5.5–12.5 GHz, demonstrates repeatable elastic deformation. Using a transmit/receive measurement setup, the composite scattering response is measured over the frequency interval. The results indicate substantial tuning of chirality through deformation. An increase in axial strain of up to 30% yields a ∼18% change in axial chirality. (paper)

  12. Elastomeric composites with tuned electromagnetic characteristics

    Wheeland, Sara; Bayatpur, Farhad; Amirkhizi, Alireza V.; Nemat-Nasser, Sia

    2013-01-01

    This paper presents a novel elastomeric composite that exhibits a deformation-induced change in chirality. Previous efforts primarily dealt with a coil array in air without chiral tuning. Here, a composite is created that consists of an array of parallel, metallic helices of the same handedness embedded in a polymer matrix. The chiral response of the composite depends on pitch, coil diameter, wire thickness and coil spacing; however, pitch has the greatest effect on electromagnetic performance. The present study explores this effect by using helical elements to construct a chiral medium that can be mechanically stretched to adjust pitch. This adjustment directly affects the overall chirality of the composite. A prototype sample of the composite, fabricated for operation between 5.5-12.5 GHz, demonstrates repeatable elastic deformation. Using a transmit/receive measurement setup, the composite scattering response is measured over the frequency interval. The results indicate substantial tuning of chirality through deformation. An increase in axial strain of up to 30% yields a ˜18% change in axial chirality.

  13. Development of a snubber type magnetorheological fluid elastomeric lag damper for helicopter stability augmentation

    Ngatu, Grum T.

    Most advanced helicopter rotors are typically fitted with lag dampers, such as elastomeric or hybrid fluid-elastomeric (FE) lag dampers, which have lower parts counts, are lighter in weight, easier to maintain, and more reliable than conventional hydraulic dampers. However, the damping and stiffness properties of elastomeric and fluid elastomeric lag dampers are non-linear functions of lag/rev frequency, dynamic lag amplitude, and operating temperature. It has been shown that elastomeric damping and stiffness levels diminish markedly as amplitude of damper motion increases. Further, passive dampers tend to present severe damping losses as damper operating temperature increases either due to in-service self-heating or hot atmospheric conditions. Magnetorheological (MR) dampers have also been considered for application to helicopter rotor lag dampers to mitigate amplitude and frequency dependent damping behaviors. MR dampers present a controllable damping with little or no stiffness. Conventional MR dampers are similar in configuration to linear stroke hydraulic type dampers, which are heavier, occupy a larger space envelope, and are unidirectional. Hydraulic type dampers require dynamic seal to prevent leakage, and consequently, frequent inspections and maintenance are necessary to ensure the reliability of these dampers. Thus, to evaluate the potential of combining the simplicity and reliability of FE and smart MR technologies in augmenting helicopter lag mode stability, an adaptive magnetorheological fluid-elastomeric (MRFE) lag damper is developed in this thesis as a retrofit to an actual fluid-elastomeric (FE) lag damper. Consistent with the loading condition of a helicopter rotor system, single frequency (lag/rev) and dual frequency (lag/rev at 1/rev) sinusoidal loading were applied to the MRFE damper at varying temperature conditions. The complex modulus method was employed to linearly characterize and compare the performance of the MRFE damper with the

  14. Estimation of pressure drop in gasket plate heat exchangers

    Neagu Anisoara Arleziana

    2016-06-01

    Full Text Available In this paper, we present comparatively different methods of pressure drop calculation in the gasket plate heat exchangers (PHEs, using correlations recommended in literature on industrial data collected from a vegetable oil refinery. The goal of this study was to compare the results obtained with these correlations, in order to choose one or two for practical purpose of pumping power calculations. We concluded that pressure drop values calculated with Mulley relationship and Buonopane & Troupe correlation were close and also Bond’s equation gave results pretty close to these but the pressure drop is slightly underestimated. Kumar correlation gave results far from all the others and its application will lead to oversize. In conclusion, for further calculations we will chose either the Mulley relationship or the Buonopane & Troupe correlation.

  15. Generation and detection of gigahertz surface acoustic waves using an elastomeric phase-shift mask

    Li, Dongyao; Zhao, Peng; Zhao, Ji-Cheng; Cahill, David G.

    2013-10-01

    We describe a convenient approach for measuring the velocity vSAW of surface acoustic waves (SAWs) of the near-surface layer of a material through optical pump-probe measurements. The method has a lateral spatial resolution of elastomeric polydimethylsiloxane phase-shift mask which is fabricated using a commercially available Si grating as a mold. Time-domain electromagnetics calculations show, in agreement with experiment, that the efficiency of the phase-shift mask for generating and detecting SAWs decreases rapidly as the periodicity of the mask decreases below the optical wavelength. We validate the experimental approach using bulk and thin film samples with known elastic constants.

  16. Influence of elastomeric seal plate surface chemistry on interface integrity in biofouling-prone systems: Evaluation of a hydrophobic "easy-release" silicone-epoxy coating for maintaining water seal integrity of a sliding neoprene/steel interface

    Andolina, Vincent L.

    The scientific hypothesis of this work is that modulation of the properties of hard materials to exhibit abrasion-reducing and low-energy surfaces will extend the functional lifetimes of elastomeric seals pressed against them in abrasive underwater systems. The initial motivation of this work was to correct a problem noted in the leaking of seals at major hydropower generating facilities subject to fouling by abrasive zebra mussel shells and extensive corrosion. Similar biofouling-influenced problems can develop at seals in medical devices and appliances from regulators in anesthetic machines and SCUBA diving oxygen supply units to autoclave door seals, injection syringe gaskets, medical pumps, drug delivery components, and feeding devices, as well as in food handling equipment like pasteurizers and transfer lines. Maritime and many other heavy industrial seal interfaces could also benefit from this coating system. Little prior work has been done to elucidate the relationship of seal plate surface properties to the friction and wear of elastomeric seals during sliding contacts of these articulating materials, or to examine the secondary influence of mineralized debris within the contacting interfaces. This investigation utilized the seal materials relevant to the hydropower application---neoprene elastomer against carbon steel---with and without the application of a silicone-epoxy coating (WearlonRTM 2020.98) selected for its wear-resistance, hydrophobicity, and "easy-release" capabilities against biological fouling debris present in actual field use. Analytical techniques applied to these materials before and after wear-producing processes included comprehensive Contact Angle measurements for Critical Surface Tension (CA-CST) determination, Scanning Electron Microscopic inspections, together with Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-Ray Fluorescence (XRF) measurements for determination of surface texture and inorganic composition, Multiple

  17. Development of UHV compatible machined diamond profile gaskets for INDUS-2

    Yadav, D. P.; Shiroman, R.; Shukla, S. K.; Kotaiah, S.

    2008-05-01

    Ultra High Vacuum (UHV) compatible demountable joints are needed in Indus-2 (2.5 GeV, 300mA) electron storage ring for connecting Al-alloy vacuum chambers (homogeneous joints) as well as Al-alloy vacuum chambers to well proven stainless steel components like beam diagnostic components and RF-shielded bellow assemblies (heterogeneous joints). Bakeable & reliable diamond profile Al-alloy gaskets have been developed for Helium leak rate less than 2×10-10 Std. CC/sec, which eliminated the need of any Al to SS transition pieces onto the Aluminium vacuum chambers. Salient features of these gaskets are: high reliability, low cost, reduced flange thickness, self alignment, ease in installation, less torque requirement, formability to non-circular shape & ultra cleanliness. These diamond profile gaskets were machined from extruded Al-alloy 6061-T5 pipes using specially developed high-speed steel formed cutting tools. Thermal cyclic tests were carried to check the reliability of these gaskets. No leaks were found even after several bakeouts at 150°C. Non-circular metallic gaskets like the one used in UHV gate valve bonnet seal can also be manufactured using specially developed formed toolings. This paper describes basic design philosophy, manufacturing process and testing details of these gaskets.

  18. Development of UHV compatible machined diamond profile gaskets for INDUS-2

    Ultra High Vacuum (UHV) compatible demountable joints are needed in Indus-2 (2.5 GeV, 300mA) electron storage ring for connecting Al-alloy vacuum chambers (homogeneous joints) as well as Al-alloy vacuum chambers to well proven stainless steel components like beam diagnostic components and RF-shielded bellow assemblies (heterogeneous joints). Bakeable and reliable diamond profile Al-alloy gaskets have been developed for Helium leak rate less than 2x10-10 Std. CC/sec, which eliminated the need of any Al to SS transition pieces onto the Aluminium vacuum chambers. Salient features of these gaskets are: high reliability, low cost, reduced flange thickness, self alignment, ease in installation, less torque requirement, formability to non-circular shape and ultra cleanliness. These diamond profile gaskets were machined from extruded Al-alloy 6061-T5 pipes using specially developed high-speed steel formed cutting tools. Thermal cyclic tests were carried to check the reliability of these gaskets. No leaks were found even after several bakeouts at 150 deg. C. Non-circular metallic gaskets like the one used in UHV gate valve bonnet seal can also be manufactured using specially developed formed toolings. This paper describes basic design philosophy, manufacturing process and testing details of these gaskets

  19. COMPARATIVE PERFORMANCE STUDY OF GASKETED AND NON-GASKETED FLANGE JOINTS UNDER COMBINED INTERNAL PRESSURE, AXIAL AND BENDING LOADING – AN EXPERIMENTAL STUDY

    Muhammad Abid

    2010-11-01

    Full Text Available In this paper result of an extensive comparative experimental study of a gasketed and non-gasketed flange joint with different assemblies with different combined load combinations is carried out to investigate joint performance i.e. joint strength and sealing capability. Actual joint load capacities are determined under both the design and proof test pressure with maximum additional external loading (axial and bending that can be applied for safe joint performance. In addition, application of combined load is also discussed in the light of equivalent pressure approach.

  20. Evaluation of the effect of different stretching patterns on force decay and tensile properties of elastomeric ligatures

    Aminian, Amin; Nakhaei, Samaneh; Agahi, Raha Habib; Rezaeizade, Masoud; Aliabadi, Hamed Mirzazadeh; Heidarpour, Majid

    2015-01-01

    Background: There have been numerous researches on elastomeric ligatures, but clinical conditions in different stages of treatment are not exactly similar to laboratory conditions. The aim of this in vitro study was to simulate clinical conditions and evaluate the effect of three stretching patterns on the amount of force, tensile strength (TS) and extension to TS of the elastomers during 8 weeks. Materials and Methods: Forces, TS and extension to TS of two different brands of elastomers were...

  1. Antimicrobial effect of zataria multiflora extract in comparison with chlorhexidine mouthwash on experimentally contaminated orthodontic elastomeric ligatures.

    Hossein Aghili; Abbas Ali Jafari Nadoushan; Vahid Herandi

    2015-01-01

    Objectives: Long-term use of orthodontic appliances and fixation ligatures creates a favorable environment for the accumulation of oral normal microflora and increases the risk of enamel demineralization and periodontal disease. The aim of this study was to compare the antimicrobial effects of Zataria Multiflora extract and 0.2% chlorhexidine (CHX) mouthwash on experimentally contaminated orthodontic elastomeric ligatures. Materials and Methods: In this lab trial study, Iranian and foreign-ma...

  2. Mechanical-property changes of structural composite materials after low-temperature proton irradiation: Implications for use in SSC magnet systems

    Long-term physical, mechanical, electrical, and other properties of advanced composites, plastics, and other polymer materials are greatly affected by high-energy proton, neutron, electron, and gamma radiation. The effects of high-energy particles on materials is a critical design parameter to consider when choosing polymeric structural, nonstructural, and elastomeric matrix resin systems. Polymer materials used for filled resins, laminates, seals, gaskets, coatings, insulation and other nonmetallic components must be chosen carefully, and reference data viewed with caution. Most reference data collected in the high-energy physics community to date reflects material property degradation using other than proton irradiations. In most instances, the data were collected for room-temperature irradiations, not 4.2 K or other cryogenic temperatures, and at doses less than 108-109 Rad. Energetic proton (and the accompanying spallation-product particles) provide good simulation fidelity to the expected radiation fields predicted for the cold-mass regions of the SSC magnets, especially the corrector magnets. The authors present here results for some structural composite materials which were part of a larger irradiation-characterization of polymeric materials for SSC applications

  3. Prediction of Leakage Rates Through Sealing Connections with Nonmetallic Gaskets%非金属平垫片密封连接的泄漏率预测

    顾伯勤; 陈晔; 朱大胜

    2007-01-01

    In this work,a model of gas leakage through nonmetallic gaskets was developed in order to predict leakage rate of gasket sealing connections. The model was verified by the leakage experiments on two types of gaskets: compressed non-asbestos fiber gasket and flexible graphite gasket reinforced with tanged metal sheet. The coefficients in the leakage rate formula were obtained by regression of experimental data for each type of gasket.The model was also validated against the experimental leakage data by other researchers and shown to produce accurate predications. Furthermore,the model was applied to a bolted flanged connection in service in order to assess the tightness of the connection.

  4. Reduction of molecular gas diffusion through gaskets in leaf gas exchange cuvettes by leaf‐mediated pores

    Boesgaard, Kristine Stove; Mikkelsen, Teis Nørgaard; Ro‐Poulsen, Helge;

    2013-01-01

    There is an ongoing debate on how to correct leaf gas exchange measurements for the unavoidable diffusion leakage that occurs when measurements are done in non‐ambient CO2 concentrations. In this study, we present a theory on how the CO2 diffusion gradient over the gasket is affected by leaf......‐mediated pores (LMP) and how LMP reduce diffusive exchange across the gaskets. Recent discussions have so far neglected the processes in the quasi‐laminar boundary layer around the gasket. Counter intuitively, LMP reduce the leakage through gaskets, which can be explained by assuming that the boundary layer...

  5. Modified Sierpinski Gasket for Wi-Fi and WLAN Applications

    Manoj Choudhary

    2015-05-01

    Full Text Available The hasty growth of wireless technologies has drawn new demands for integrated components including antennas and antenna on chip is a new mantra in the area of antenna research. Various techniques have been suggested by researchers for the miniaturization of microstrip patch antennas with multiband characteristics. Numerous antennas for multiband operation have been studied and designed for communication and radar systems. One of the solutions for the multiband characteristics is the fractal antenna. The Fractal antennas are based on the concept of fractal geometries. They can be designed in a variety of shapes in order to obtain enhanced gain and bandwidth, dual band and circular polarization to even ultra-wideband operation. In this paper, the fractal antenna has been designed using the Arlon substrate with relative permittivity of 1.3 and a substrate of Sierpinski gasket shaped placed on it. Feed used is the line feed. The designed antenna is a low profile, small size and multiband antenna since it can be operated at different frequencies within the frequency range of (1.75 – 2.65 and (5.7 – 7.65 GHz. It includes the frequencies used for wireless WLAN application and used to receive and transmit a high-frequency signal.

  6. A BRIEF TALK ON THE SPIRAL WOUND GASKET STIPULATIONS OF NATIONAL STANDARD AND AMERICAN STANDARD%浅谈国标与美标关于缠绕式垫片的规定

    尹远福

    2001-01-01

    缠绕式垫片是一种密封性能好使用较广泛的垫片,许多国家对此均有相应的标准,并做出了相关的规定。文中介绍了我国国家标准GB4622.1~4622.3-93《缠绕式垫片》和美国机械工程师协会ASMEB16.20-1993《Metallic Gaskets for Pipe Flanges—Ring-Joint,Spiral-Wound,and Jacketed》标准在垫片适用范围、结构型式、垫片材料和标志等方面的相同点和不同点。%Spiral wound gasket has a good seal property and is used inwidespead range.Many countries have this relative standards,and stipulate the corresponding regulation.The same and different views in the fields of scope,structure type,gasket material and mark etc,between our national standard GB4622.1~4622.3-93“spiral wound gasket”and ASME B16.20-1993“Metallic gasket for pipe flange-ring joint,spiral wound and jacketed”standard are recommended.

  7. 非金属垫片螺栓法兰连接寿命评价%Life Assessment of Non-metallic Gasket Bolted Flanged Connections 

    孙振国; 顾伯勤

    2011-01-01

    分析非金属垫片密封的时效特性,考虑高温条件下材料退化和垫片载荷松弛过程对密封性能的影响,依据多孔介质理论,建立非金属垫片密封的时效泄漏模型.将螺栓法兰连接系统寿命划分为密封寿命和部件寿命.提出密封寿命试验方法,在考虑垫片泄漏特性变化的基础上,基于指标泄漏率分析螺栓法兰连接系统密封寿命;基于蠕变和疲劳损伤准则分析高温螺栓的剩余寿命,探讨螺栓法兰连接系统的密封寿命和各部件寿命之间的关系.建立螺栓法兰连接系统的寿命预测最弱环模型,将垫片的变形特性和泄漏特性统一于螺栓法兰连接系统中进行研究,提出基于指标泄漏率和结构完整性的螺栓法兰连接系统寿命评价方法.%The time-correlated leakage characteristic of nonmetallic gaskets was analyzed. Considering the effect of the gasket compressive stress relaxation and the deterioration of material on gasket sealing performance at elevated temperature,a time-correlated leakage prediction model of non-metallic gasket sealing connections based on the porous medium theory was proposed. The life of bolted flanged connections was divided into sealing life and component life. A testing method of sealing life was put forward,the sealing life can be predicted based on target leakage rate in considering the change of gasket leakage characteristic,and the life of bolts can be obtained based on creep and fatigue damage criterion. The relationship between sealing life and component life of sealing system was discussed, and a weakest-link model for predicting the life of bolted flanged connections was established. A life evaluation method of bolted flanged connections based on the target leakage rate and the structural integrity was proposed, in which the deformation and leakage characteristic of the sealing system were both taken into consideration.

  8. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa

    Meier, Thomas; Haase, Jürgen [Faculty of Physics and Earth Sciences, University of Leipzig, Linnéstrasse 5, Leipzig 04103 (Germany)

    2015-12-15

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al{sub 2}O{sub 3}), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures.

  9. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al2O3), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures

  10. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa

    Meier, Thomas; Haase, Jürgen

    2015-12-01

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al2O3), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures.

  11. Design of Sealing of High Pressure Flange Bolts Using Gasket Safety Factor%采用垫片安全系数的高压法兰螺栓密封设计

    陈孙艺

    2015-01-01

    为了防治高压大直径法兰螺栓密封的设计失效,从影响法兰密封效果的因素中提出垫片特性及垫片受力非均匀性2个参数;以垫片系数和垫片预紧比压为基础,分析特性比和特性系数这2个反映垫片组合特性的新概念;提出以垫片安全系数表征垫片的结构形式和材料性能在不同计算压力下的安全储备。绘制了典型的安全系数曲线,安全系数随着计算压力的增大而降低,且曲线下降中存在单个拐点;垫片适用压力大于拐点压力,小于垫片安全系数等于1时的计算压力。应用各种垫片在不同安全系数下相应的计算压力适用值进行密封设计,能够确保密封结构设计的有效性。%In order to prevent design failure on sealing of large diameter flange bolts under high pressure,two worth pa⁃rameters were put forward from the factors relation to the failure on sealing of high pressure flange bolts,which included gasket characteristic and inhomogeneous gasket stresses.New concepts of both characteristic ratio and characteristic factor that reflected gasket general characteristics were analyzed based on gasket factor and pre⁃tightening unit sealing load.Gas⁃ket safety factor was presented to characterize the safety remain of both structure and material characteristic under different calculation pressure.Typical safety factor curve was drawn that safety factor was descends as calculated pressure increased, and there was one inflexion during descending. Gasket applied pressure was greater than the inflexion pressure, and was smaller than the calculated pressure of safety factor was equal to 1�0.The method that uses the pressure calculated for all kinds of gasket at different safety factor to design the gasket sealing can ensure the effectiveness of sealing structure.

  12. The method for decrease of helium gas leak with double O-ring rubber gasket

    Nuclear components are required to be highly airtight. To get satisfactory airtightness, helium leak detection had been used. However helium gas atom is smaller than other gas atom except hydrogen and so has very high permeability. Therefore, leak of helium gas atom from O-ring rubber gasket was detected by helium leak detector in airtight test. It is very difficult to distinguish permeation from leakage. To solve the problem, we made double O-ring rubber gasket and tested its ability of decreasing permeation, examined its effect. As a result of the test and the examination, we found the gap between outer ring and inner ring of double O-ring rubber gasket was very important for decrease permeation helium gas. (author)

  13. Gasket like relief valve%密封圈式安全阀

    吕文柱; 孙震; 李泽锋; 唐宏伟; 赵芳

    2001-01-01

    针对弹簧式安全阀高压工作时开闭可靠性差,而销钉、膜片式安全阀不耐疲劳状况,设计出密封圈式一次动作安全阀。未超载时,密封圈密封保压,超载时,密封圈爆破,失去密封作用而泄压。%In order to solving the problems of the poor stability of spring relief valve working under high pressure and the poor fatigue resistance of pin and membrane relief valve, an one-off gasket like relief valve is designed. The gasket keep the pressure when the load is under the safe value, otherwise, the gasket breaks and relieves the load.

  14. Sealing performance of flexible graphite corrugated metal composite gaskets%柔性石墨金属波纹复合增强垫片密封性能试验

    励行根; 沈明学; 王成林; 魏世军; 励洁; 彭旭东

    2015-01-01

    The leakage ratio, compression recovery and stress-relaxation of flexible graphite corrugated metal composite gaskets with 316L and A3 steel as framework were tested on an automatic multi-function gasket testing rig. The effects of flexible graphite cover layer thickness, frame material and gasket stress on sealing performance and mechanical properties were investigated. The residual thickness of corrugated metal was determined at different thicknesses of cover layer and gasket stresses. The sealing performance of the composite gasket was mainly dependent upon the thickness of cover layer with flexible graphite, and optimal sealing performance was observed for the corrugated metal when the thickness of cover layer was 0.6 mm. The composite gaskets had good carrying capacity and sealing performance, which was especially suitable for complex applications, such as pressure and temperature fluctuations. Also outstanding recovery of the composite gaskets could be obtained by pre-compression. In addition, as gasket stress increased, sealing and compression recovery performance of 316L composite gaskets became obviously better than the composite gaskets with A3 steel as framework, and the former had distinct improvement than the latter in resisting stress relaxation and creep behavior.%在全自动垫片综合性能试验台上分别进行了316L和A3钢作为骨架材料的金属波纹复合垫片的泄漏率、压缩回弹性能和应力松弛试验,考察了柔性石墨覆盖层厚度、骨架材质和垫片应力对垫片密封性能和力学性能的影响,分析了不同覆盖层厚度和垫片应力下的金属波纹残余高度。结果表明:覆盖层厚度对垫片的密封性能有重要影响,厚度为0.6 mm 时该类垫片的综合性能最佳;金属波纹复合垫片具有良好的承载能力和密封性能,尤其适宜压力波动、温度剧变等场合的密封,预压缩处理更能真实反映出复合垫片优异

  15. Radiation dose estimation on rubber gaskets for remote repair of leaky helium flange joints in Cirus reactor

    Full text: The paper describes the analysis of the neutronic and gamma radiation dose on the rubber gaskets located within the reactor structure of Cirus after nearly 35 years of reactor operation. These gaskets are used in the flange joints of helium cover gas pipelines, some of which developed leak. This cumulative radiation dose was required to assess the compressive properties of the irradiated gaskets. After estimating the dose, fresh gaskets were procured and irradiated to comparable gamma dose. These gaskets were then tested in a universal testing machine and load versus deflection data were generated. A remote repair method of clamping the leaky flanges was developed. The data were used in the detailed piping analysis and the sequence and the extent of compression of flange joints was decided. Split sealing clamps were remotely installed and tightened to reduce the leaks significantly

  16. Assessing patient preference for two types of elastomeric infusion device.

    Dodd, Susan

    Home administration of antibiotic therapy to cystic fibrosis patients is one of many applications for the use of elastomeric infusion devices. Patient acceptability can significantly affect adherence to complex drug regimens with concordance being a concern in this patient population. While patient acceptance is often cited as a factor in pump selection, patient preference has not been assessed within a particular class of infusion device. The objective of this study was to assess patient preference for one type of elastomeric infusion device (Baxter Intermate--hard-shelled design) or another (Fresenius Kabi Eclipse--soft-shelled design). Twenty-four patients entered the study. 20/24 (83%) patients expressed a preference for the Eclipse, while 4/24 (17%) stated no preference for either device. The Eclipse device was found to be much more favourable in terms of comfort and discreetness. Patient preference should therefore be given significant consideration in order to maximize concordance with drug regimens. PMID:18026019

  17. Progressive die for copier gasket%复印机垫片级进模设计

    王娟; 吴正策

    2012-01-01

    The stamping process of a copier gasket was analyzed and the general structure and layout design of a multi-position progressive die for the gasket were presented.%分析了复印机垫片的冲压成形工艺,介绍了垫片多工位级进模总体结构设计、排样方式.生产实践证明,该模具生产的零件符合尺寸精度要求.

  18. AN APPROXIMATION METHOD TO ESTIMATE THE HAUSDORFF MEASURE OF THE SIERPINSKI GASKET

    Ruan Huojun; Su Weiyi

    2004-01-01

    In this paper, we firstly define a decreasing sequence {Pn(S)} by the generation of the Sierpinski gasket where each pn(S) can be obtained in finite steps. Then we prove that the Hausdorff measure Hs(S)of the Sierpinski gasket S can be approximated by {Pn(S)} with Pn(S)/(1 + 1/2n-3)s ≤ Hs(S) ≤ pn(S).An algorithm is presented to get Pn(S) for n ≤ 5. As an application, we obtain the best lower bound of Hs(S) till now: Hs(S) ≥ 0.5631.

  19. THE INFLUENCE OF OBLIQUE COLLISION OF THE GASKET OF A GAS REGULATOR ON SAFETY SHUTDOWN

    2012-11-01

    Full Text Available In this work the author presents a theoretical study on the conduct during the impact of the gasket at the intake of combustible gas, when the regulatory mechanism is controlled by a thermostat. For this case, the author analyzed two aspects involved in the operation of the proposed experimental model: - The oblique impact of the cinematic elements of the regulatory mechanism; - The influence of elasticity on deformation of the gasket at impact. Furthermore, the paper presents the modeling and dynamic analysis of the mechanism MSC ADAMS

  20. Evaluation of Fillers Dispersion Degree in Elastomeric Magnetic Composites

    Ján Kruželák; Sybill Ilisch; Ivan Hudec; Rastislav Dosoudil

    2012-01-01

    Elastomeric magnetic composites were prepared by incorporation of strontium ferrite into polymer matrices based on natural as well as butadiene rubber. Besides the rubber and ferrite, or the combinations of ferrite and carbon black (in case of natural rubber), the model rubber compounds contained only ingredients which support curing process. The study was dedicated to the observation of fillers dispersion degree in the rubber matrices and investigation of physical-mechanical and magnetic pro...

  1. Elastomeric microfluidic diode and rectifier work with Newtonian fluids

    Liu, John; Yan CHEN; Taylor, Clive R.; Scherer, Axel; Kartalov, Emil P.

    2009-01-01

    We report on two microfluidic elastomeric autoregulatory devices—a diode and a rectifier. They exhibit physically interesting and complex nonlinear behaviors (saturation, bias-dependent resistance, and rectification) with a Newtonian fluid. Due to their autoregulatory properties, they operate without active external control. As a result, they enable increased microfluidic device density and overall system miniaturization. The demonstrated diode and rectifier would also be useful components in...

  2. Interaction of Reinforced Elastomeric Bearings in Bridge Construction

    Nittmannová Ľubica; Magura Martin

    2016-01-01

    The aim of this paper is to demonstrate the behavior of reinforced elastomeric bearings under various loads. They are made of special types of bearings. The experimental verification of these special bearings has been tested on various types of loading. The results of the experimental measurements are compared with the results of the numerical modeling and calculations according to the standard assumptions in STN EN 1337-3. In the conclusion, the results are summarized for the selected types ...

  3. Local Anaesthetic Infusion with Elastomeric Pump After Arthroscopic Subacromial Decompression

    Little, Kevin; Pillai, Anand; Fazzi, Umberto; Storey, Neil

    2007-01-01

    INTRODUCTION The use of extended local anaesthesia for postoperative pain has previously been reported, and has several advantages over other methods, including ease of placement, safety, reliability, lower cost and effective analgesia. We present our experience with a portable elastomeric infusion device in patients undergoing arthroscopic subacromial decompression, and make a case for its potential to allow same-day discharge. PATIENTS AND METHODS Forty patients undergoing arthroscopic subacromial decompression were followed-up. At the end of the procedure, an epidural catheter connected to a portable elastomeric local anaesthetic infusion system was inserted into the subacromial space. All patients were electively admitted for overnight stay postoperatively and assessed using a visual analogue scale (VAS) to evaluate their level of pain. RESULTS No patient reported severe pain at any stage. None of the patients required any parenteral opiate analgesia with the pump in situ. CONCLUSIONS These findings suggest that the use of this elastomeric infusion device following shoulder surgery allows safe and early discharge of patients with decreased need for parenteral opiate analgesia. PMID:17535622

  4. New Soft Polymeric Materials Applicable as Elastomeric Transducers

    Bejenariu, Anca Gabriela; Skov, Anne Ladegaard

    range of temperature10-13. However, silicone elastomer has weak intermolecular forces among polymeric chains, which limits its mechanical strength. Mechanical properties may be improved using different methods (adding fillers14, interpenetrating network synthesis15 or bimodal network synthesis16). In...... ideal springs. The viscoelastic behavior as function of the applied frequency (LVE diagram) is shown for different hyperswollen networks with varying stoichiometric imbalance (r). The results are compared with results of similar un-swollen networks. The hyperswollen networks are significantly softer and...

  5. Preparation and Analysis of Non-asbestos Sealing Gasket%抄取无石棉密封垫片的制备及分析

    张萌; 刘美红; 袁希晨; 贾有东; 陈涛

    2014-01-01

    利用纤维混杂效应,综合有机和无机纤维的优点,选用合适的多种无机纤维和有机纤维,制备出达到一定使用要求,具有较好性价比的无石棉密封垫片,获得了工业化生产的基本工艺和材料配比,并对所研制的无石棉密封垫片进行了对比分析。结果表明,采用胶乳抄取工艺,利用不含石棉成分的无机纤维与有机纤维混杂增强橡胶粘接剂制备的新型密封垫片,达到了国外同类产品的性能指标,形成了具有我国特色的无石棉密封材料。%According to the fiber hybrid effect,the merits of organic and inorganic fibers were integrated.The appropri-ate organic and inorganic fibers were chosen to prepare the non-asbestos gasket which can meet the usage requirements and had a good cost performance.The ratio of basic craft and materials for industrial production were obtained.Basic research and comparing on the non-asbestos gasket were conducted.Results indicated that the new non-asbestos gasket which was made by non-asbestos fibers enhanced rubber adhesive and reached the level of similar international products.It has formed unique non-asbestos sealing materials of our country.

  6. In-use Stability of Ceftaroline Fosamil in Elastomeric Home Infusion Systems and MINI-BAG Plus Containers.

    Bhattacharya, Sisir; Parekh, Satish; Dedhiya, Mahendra

    2015-01-01

    The objective of this study was to determine in-use stability of ceftaroline fosamil infusion solution of concentrations up to 12 mg/mL in elastomeric home infusion system prefilled with 0.9% Sodium Chloride Injection USP or 5% Dextrose Injection USP and MINI-BAG Plus Container delivery devices prefilled with 0.9% sodium chloride injection. In-use ceftaroline fosamil infusion solution (12 mg/mL) was prepared for elastomeric home infusion systems (Homepump Eclipse, Baxter Intermate, and AccuRx Elastomeric Pump) pre-filled with either 0.9% sodium chloride injection or 5% dextrose; or Baxter MINI-BAG Plus Containers pre-filled with 0.9% Sodium Chloride Injection USP (4 mg/mL to 12 mg/mL ceftaroline fosamil in final solution). The systems were stored refrigerated for 24 hours followed by up to 6 hours of storage at room temperature. Samples were analyzed at various time points for assay and degradation product by a validated stability-indicating high-performance liquid chromatography method. In-use ceftaroline fosamil infusion solution, ranging from 4-mg/mL to a maximum of 12-mg/mL concentration, in elastomeric home infusion systems prefilled with 0.9% sodium chloride injection or 5% dextrose, and MINI-BAG Plus Containers prefilled with 0.9% sodium chloride injection were chemically stable for up to 24 hours refrigerated at 2°C to 8°C (36°F to 46°F) and up to 6 hours at room temperature and had acceptable compatibility with material used. Ceftaroline fosamil (4 mg/mL to 12 mg/mL) maintains its potency for up to 24 hours refrigerated at 2°C to 8°C (36°F to 46°F) and up to 6 hours of storage at room temperature upon reconstitution in infusion solution with 0.9% sodium chloride or 5% dextrose when used in elastomeric home infusion system and MINI-BAG Plus Containers delivery devices prefilled with 0.9% sodium chloride injection. PMID:26775451

  7. The oscillation of the occupation time process of super- Brownian motion on Sierpinski gasket

    郭军义

    2000-01-01

    The occupation time process of super-Brownian motion on the Sierpinski gasket is studied. It is shown that this process does not possess stable property in the long run, but oscillates periodically in some sense. Other convergence properties are also studied.

  8. The oscillation of the occupation time process of super-Brownian motion on Sierpinski gasket

    2000-01-01

    The occupation time process of super-Brownian motion on the Sierpinski gasket is studied. It is shown that this process does not possess stable property in the long run, but oscillates periodically in some sense. Other convergence properties are also studied.

  9. Optimization of fractional composition of the excipient in the elastomeric covering for asphalt highways

    E. M. Nurullaev

    2013-04-01

    Full Text Available The computational method of optimum fractional composition of a dispersible filler of polymeric composite on the basis of three-dimensionally linked elastomer is developed according to non-linear programming. The coefficient of dynamic viscosity of polymeric suspension or the initial module of a viscoelasticity of the join solidification low-molecular rubbers with the final functional groups, filled by many fractional dioxide of silicon are considered as criteria of optimization. Influence of the limiting volume filling on energy of mechanical destruction was investigated. The elastomeric material is offered for use as a covering of asphalt highways in the form of a frost-proof waterproofing layer, which allowing multiply to increase operating properties.

  10. Seismic response analysis of base isolated structures with high damping elastomeric bearings

    Seismic response analysis of base-isolated structures with high damping elastomeric bearings is described in this paper. Emphasis is placed on the adaptation of a nonlinear constitutive model for the isolation bearing together with the treatment of foundation embedment for the soil-structure-interaction analysis. The constitutive model requires six input parameters derived from bearing experimental data under sinusoidal loading. The characteristic behavior of bearing, such as the variation of shear modulus and material damping with the change of maximum shear deformation, can be captured closely by the formulation. In the treatment of soil embedment a spring method is utilized to evaluate the foundation input motion as well as soil stiffness and damping. The above features have been incorporated into a three-dimensional system response program, SISEC, developed at Argonne National Laboratory. Sample problems are presented to illustrate the relative response of isolated and unisolated structures

  11. Silicon micro-masonry using elastomeric stamps for three-dimensional microfabrication

    We present a micromanufacturing method for constructing microsystems, which we term ‘micro-masonry’ based on individual manipulation, influenced by strategies for deterministic materials assembly using advanced forms of transfer printing. Analogous to masonry in construction sites, micro-masonry consists of the preparation, manipulation, and binding of microscale units to assemble microcomponents and microsystems. In this paper, for the purpose of demonstration, we used microtipped elastomeric stamps as manipulators and built three dimensional silicon microstructures. Silicon units of varied shapes were fabricated in a suspended format on donors, retrieved, delivered, and placed on a target location on a receiver using microtipped stamps. Annealing of the assembled silicon units permanently bound them and completed the micro-masonry procedure. (paper)

  12. Flame resistant elastomeric polymer development. [for use in space shuttle instrument packaging

    Howarth, J. T.; Sheth, S. G.; Sidman, K. R.

    1975-01-01

    Elastomeric products were developed for use in the space shuttle program, and investigations were conducted to improve the properties of elastomers developed in previous programs, and to evaluate the possibility of using lower-cost general purpose polymers. Products were fabricated and processed on conventional processing equipment; these products include: foams based on fluorinated rubber flame-retarded compounds with a density of 20-30 pounds/cubic foot for use as padding and in helmets; foams based on urethane for use in instrument packaging in the space shuttle; flexible and semi-rigid films of fluorinated rubber and neoprene compounds that would not burn in a 70% nitrogen, 30% oxygen atmosphere, and in a 30% nitrogen, 70% oxygen atmosphere, respectively for use in packaging or in laminates; coated fabrics which used both nylon and Kelvar fabric substrates, coated with either fluorinated or neoprene polymer compositions to meet specific levels of flame retardancy; and other flame-resistant materials.

  13. 49 CFR 173.40 - General packaging requirements for toxic materials packaged in cylinders.

    2010-10-01

    ... valve must have a taper-threaded connection directly to the cylinder and be capable of withstanding the... be sealed by a threaded cap or threaded solid plug and inert gasketing material. (4) The materials...

  14. Inspection of Fuel Cladding and Metal Gasket in Metallic Dry Cask at Tokai No. 2 Power Station

    The metallic dry cask storage of spent fuel started in December 2001 at TOKAI No.2 power station. The cask that had served for 7 years was inspected in January 2009. The objective of this inspection is confirmation of fuel cladding and metal gasket integrity. This cask accommodates 8 × 8 zirconium liner type fuel. The gasket applied to this cask consists of aluminum outer lining and Inconel spring. This inspection confirmed that there had been no damage in fuel cladding and metal gasket during the storage for 7 years. (author)

  15. PRELIMINARY REPORT: EFFECTS OF IRRADIATION AND THERMAL EXPOSURE ON ELASTOMERIC SEALS FOR CASK TRANSPORTATION AND STORAGE

    Verst, C.; Skidmore, E.; Daugherty, W.

    2014-05-30

    A testing and analysis approach to predict the sealing behavior of elastomeric seal materials in dry storage casks and evaluate their ability to maintain a seal under thermal and radiation exposure conditions of extended storage and beyond was developed, and initial tests have been conducted. The initial tests evaluate the aging response of EPDM elastomer O-ring seals. The thermal and radiation exposure conditions of the CASTOR® V/21 casks were selected for testing as this cask design is of interest due to its widespread use, and close proximity of the seals to the fuel compared to other cask designs leading to a relatively high temperature and dose under storage conditions. A novel test fixture was developed to enable compression stress relaxation measurements for the seal material at the thermal and radiation exposure conditions. A loss of compression stress of 90% is suggested as the threshold at which sealing ability of an elastomeric seal would be lost. Previous studies have shown this value to be conservative to actual leakage failure for most aging conditions. These initial results indicate that the seal would be expected to retain sealing ability throughout extended storage at the cask design conditions, though longer exposure times are needed to validate this assumption. The high constant dose rate used in the testing is not prototypic of the decreasingly low dose rate that would occur under extended storage. The primary degradation mechanism of oxidation of polymeric compounds is highly dependent on temperature and time of exposure, and with radiation expected to exacerbate the oxidation.

  16. Micromechanical damage and fracture in elastomeric polymers

    Heyden, Stefanie

    This thesis aims at a simple one-parameter macroscopic model of distributed damage and fracture of polymers that is amenable to a straightforward and efficient numerical implementation. The failure model is motivated by post-mortem fractographic observations of void nucleation, growth and coalescence in polyurea stretched to failure, and accounts for the specific fracture energy per unit area attendant to rupture of the material. Furthermore, it is shown that the macroscopic model can be rigorously derived, in the sense of optimal scaling, from a micromechanical model of chain elasticity and failure regularized by means of fractional strain-gradient elasticity. Optimal scaling laws that supply a link between the single parameter of the macroscopic model, namely the critical energy-release rate of the material, and micromechanical parameters pertaining to the elasticity and strength of the polymer chains, and to the strain-gradient elasticity regularization, are derived. Based on optimal scaling laws, it is shown how the critical energy-release rate of specific materials can be determined from test data. In addition, the scope and fidelity of the model is demonstrated by means of an example of application, namely Taylor-impact experiments of polyurea rods. Hereby, optimal transportation meshfree approximation schemes using maximum-entropy interpolation functions are employed. Finally, a different crazing model using full derivatives of the deformation gradient and a core cut-off is presented, along with a numerical non-local regularization model. The numerical model takes into account higher-order deformation gradients in a finite element framework. It is shown how the introduction of non-locality into the model stabilizes the effect of strain localization to small volumes in materials undergoing softening. From an investigation of craze formation in the limit of large deformations, convergence studies verifying scaling properties of both local- and non-local energy

  17. Comparison of frictional resistance between self-ligating and conventional brackets tied with elastomeric and metal ligature in orthodontic archwires

    Vanessa Vieira Leite; Murilo Baena Lopes; Alcides Gonini Júnior; Marcio Rodrigues de Almeida; Sandra Kiss Moura; Renato Rodrigues de Almeida

    2014-01-01

    OBJECTIVE: To compare the frictional resistance between self-ligating and conventional brackets tied to different types of wire. MATERIAL AND METHODS : Abzil Kirium Capelozza (Pattern I) and Easy Clip (Roth prescription) incisor brackets were used. An elastomeric ligature or a ligating wire 0.10-in was used to ligate the wire to the Abzil bracket. Three types of orthodontic archwire alloys were assessed: 0.016-in NiTi wire, 0.016 x 0.021-in NiTi wire and 0.019 x 0.025-in steel wire. Ten obser...

  18. New elastomeric silicone based networks applicable as electroactive systems

    Bejenariu, Anca Gabriela; Boll, Mads; Lotz, Mikkel R.;

    2011-01-01

    mixed in a given ratio). An alternative network formulation method is adopted in this study in order to obtain an elastomeric system with controlled topology – a so-called bimodal network. Bimodal networks are synthesized using a ‘two-step four-pot’ mixing procedure which results in a nonhomogeneous...... necessarily compromising the viscous dissipation. Several elastomers are prepared and tested for the linear viscoelastic behaviour, i.e. behaviour in the small-strain limit (up to approximately 10% strain). The bimodal networks are, however, capable of extensions up to several times their initial length but...

  19. Interaction of Reinforced Elastomeric Bearings in Bridge Construction

    Nittmannová Ľubica

    2016-03-01

    Full Text Available The aim of this paper is to demonstrate the behavior of reinforced elastomeric bearings under various loads. They are made of special types of bearings. The experimental verification of these special bearings has been tested on various types of loading. The results of the experimental measurements are compared with the results of the numerical modeling and calculations according to the standard assumptions in STN EN 1337-3. In the conclusion, the results are summarized for the selected types of bearings.

  20. Performance Study on New Type of Composite Gasket%新型组合垫片性能研究

    周先军; 刘志亮; 张维东; 宋海燕; 毕红杰; 王庆

    2012-01-01

    Structural parameters of the new type composite gasket were determined with AN-SYS, and the good compressibility and resilience were proved through the gasket press spring tests. The gasket sealing experiments showed that the leak rate curve of the new type of composite gasket changes gently with the varying medium pressure, suits for the condition of pressure fluctuation.%采用有限元分析方法确定新型组合垫片结构参数,并通过垫片压缩回弹性能试验证明了此新型垫片具有良好的压缩回弹性能.垫片密封性能试验表明,新型组合垫片随介质压力变化泄漏率曲线比较平缓,适于压力波动的场合.

  1. Development of Remote Hanford Connector Gasket Replacement Tooling for the Savannah River Site's Defense Waste Processing Facility

    The Savannah River Site's (SRS) Defense Waste Processing Facility (DWPF) requested development of tooling and equipment to remotely replace gaskets in mechanical Hanford connectors to reduce personnel radiation exposure as compared to the current hands-on method. It is also expected that radiation levels will continually increase As future higher activity waste streams are treated. The facility is well equipped with compressed air, two master-slave manipulators (MSM's) and an electro-mechanical manipulator (EMM) arm for operation of the remote tools in the work cell proposed for remotely changing the gaskets. In order to perform all of the tasks required to remotely replace Hanford connector gaskets several operations must be performed remotely, including removal of the spent gasket and retaining ring, loading the new retaining ring and gasket into the installation tool and installation of the new gasket into the Hanford connector. The Savannah River National Laboratory, SRNL developed and tested multiple tools to perform all of the necessary tasks. Removal of retaining rings from horizontal and vertical connectors is performed by separate air actuated retaining ring removal tools and is manipulated in the cell by the MSM. A new retaining ring is then placed on a platform, rotated under the conical loading tool and raised and compressed into the gasket installation tool by two linear slides actuated by air cylinders. The gasket installation tool is then pressed against the gasket sealing surface of the Hanford connector using an MSM. Actuation of a custom air cylinder overcomes the force of several different springs to align and fix the installation tool relative to the Hanford connector and seats the retaining ring and gasket. All of the tools are located on a custom work table with a pneumatic valve station that directs compressed air to the desired tool and vents the tools as needed. On July 17 and 29, 2008 the Remote Gasket Replacement Tooling was successfully

  2. 一种广义Sirpinski垫片的Hausdorff测度%Hausdorff Measure of a Class of Generalized Sirpinski Gasket

    许荣飞

    2013-01-01

    Sirpinski gasket is the classic fractals with strick self-similar property. In this paper, we will give the construction of a class of Generalized Sirpinski Gasket and the exact value of its Hausdorff measure.%Sirpinski垫片具有严格的的自相似性,本文给出了一种广义Sirpinski垫片的构造,并得到了它的Hausdorff测度准确值。

  3. ELASTOMERIC SEISMIC-PROTECTION ISOLATORS FOR BUILDINGS AND BRIDGES

    Toshio Nishi; Nobuo Murota

    2013-01-01

    A giant earthquake of magnitude 9.0 occurred in Pacific Ocean off of Tohoku District Japan on March 11,2011.The highest seismic intensity of 7 in JMA scale was recorded in Miyagi.In the Tohoku district,around 230 buildings are seismically isolated (hereafter,SI) mainly by elastomeric isolators (seismic rubber bearings).According to the official survey reports by several organizations (for example[1]),the records of those buildings have verified the effectiveness of the seismic isolation.The response acceleration of the SI buildings was reduced by 30% to 50% of the input ground acceleration.Additionally,the difference of the conditions inside the room between SI and the fixed-base buildings was obvious as well as the damage in main structures of the buildings.The displacements of the isolators by the earthquake were around 200 mm according to the records of the instruments.As a result,the performance of SI buildings and the elastomeric isolators in the Tohoku District-Off the Pacific Ocean Earthquake 2011 were excellent,and the efficiency of the seismic isolation was verified by the records of many buildings in wide area.

  4. Frictional heat analysis of mine hoist and numerical simulation on temperature field of gasket

    HAN Dong-tai; GE Shi-rong; DU Xue-ping

    2009-01-01

    The frictional performance of gaskets is greatly affected by fiictional heat in operational mine hoists. Based on frictional mechanism and heat transfer theory, the mathematical model of the temperature field of the PVC gasket in an operational mine hoist was investigated, a numerical simulation using ANSYS is presented and the distribution of the temperature and heat flux were studied under basic assumptions. The results show that the temperature gradually decreases as the radius of the model increases and the isotherms are arcs of concentric semi-circle. The heat flux is of bilateral symmetry in the model and decreases radially. The theoretical values correspond with the measured values for a short time (τ≤100 s) when the steel wire rope slides.

  5. 带八角垫与双楔角环垫的法兰接头密封性能比较%Comparison of Sealing Performance of Bolted Flange Joints with Octagonal Gasket and Double Tapered Gasket

    荣文波; 陆晓峰; 程可

    2015-01-01

    利用ABAQUS有限元软件对带新型双楔角环垫与带八角垫的螺栓法兰接头进行数值模拟分析,对预紧工况和操作工况下的螺栓与法兰应力最大值、密封面接触压力最大值以及有效密封宽度进行分析对比。结果表明:介质内压使带双楔角环垫的法兰应力最大值下降,但法兰与螺栓应力值仍高于带八角垫的法兰、螺栓应力值;法兰公称直径增加,八角垫内、外侧面的有效密封宽度逐渐减小,而双楔角环垫主、从面有效密封宽度有增大的趋势;双楔角环垫特殊的楔形结构使得主、从面接触应力在介质内压作用后下降幅度小于八角垫内、外侧面,因而具有更好的密封性能,特别是对于大法兰公称直径的密封。%The sealing performances of the bolted flange joints with double tapered gasket and octagonal gasket were an⁃alyzed by finite element software of ABAQUS. The maximum stress between flange and bolt,the maximum contact pressure on each sealing surface and the effective sealing width between two gasket were analyzed and compared under working con⁃ditions and operating conditions. The results show that the internal pressure makes the maximum stress of the flange with double tapered gasket drop, but its stress of flange and bolt is still higher than that of the flange with octagonal gasket. With the increasing of nominal diameter, the effective sealing width of the inside and outside surfaces of octagonal gasket is decreased, but the double tapered gasket shows an increasing trend in the effective sealing width of the master and slave surfaces. The special wedge structure of double tapered gasket makes the decreasing amplitude of contact stress less than the octagonal gasket under internal pressure, therefore double tapered gasket has good sealing performance, especially for the sealing of the flange joints with large nominal diameter.

  6. Self-interacting self-avoiding walks on the Sierpinski gasket

    Klein, D.J.; Seitz, W.A.

    1984-01-01

    Exact recurrence relations for generating functions for self-interacting self-avoiding random walks on a Sierpinski gasket lattice are given. Their analysis reveals that the mean end-to-end separation of N-step walks varies as Nν with ν = In (2)/ln {(7 - 5)/2}, regardless of the (finite) strength of the self-interaction. Some other properties are also determined in the large-N limit

  7. Multiple solutions for a class of nonlinear elliptic equations on the Sierpi(n)ski gasket

    HU Jiaxin

    2004-01-01

    This paper investigates a class of nonlinear elliptic equations on a fractal domain. We establish a strong Sobolev-type inequality which leads to the existence of multiple non-trivial solutions of △u + c(x)u = f(x, u), with zero Dirichlet boundary conditions on the Sierpinski gasket. Our existence results do not require any growth conditions of f(x, t)in t, in contrast to the classical theory of elliptic equations on smooth domains.

  8. Estimate for the fractal dimension of the Apollonian gasket in d dimensions.

    Farr, R S; Griffiths, E

    2010-06-01

    We adapt a recent theory for the random close packing of polydisperse spheres in three dimensions [R. S. Farr and R. D. Groot, J. Chem. Phys. 131, 244104 (2009)] in order to predict the Hausdorff dimension dA of the Apollonian gasket in dimensions 2 and above. Our approximate results agree with published values in two and three dimensions to within 0.05% and 0.6%, respectively, and we provide predictions for dimensions 4-8. PMID:20866417

  9. Estimate for the fractal dimension of the Apollonian gasket in d dimensions

    Farr, R. S.; Griffiths, E.

    2010-01-01

    We adapt a recent theory for the random close packing of polydisperse spheres in three dimensions [R. S. Farr and R. D. Groot, J. Chem. Phys. {\\bf 131} 244104 (2009)] in order to predict the Hausdorff dimension $d_{A}$ of the Apollonian gasket in dimensions 2 and above. Our approximate results agree with published values in $2$ and $3$ dimensions to within $0.05%$ and $0.6%$ respectively, and we provide predictions for dimensions $4$ to $8$.

  10. Z-Pinch Wire-Electrode Contact Resistance Studies Using Weighted and Soft Metal Gasket Contacts*

    Gomez, M. R.; Zier, J. C.; Thurtell, A. F.; French, D. M.; Gilgenbach, R. M.; Tang, W.; Lau, Y. Y.

    2008-11-01

    The contact made between z-pinch wires and electrodes has a significant effect on both the energy deposited in the wires and the uniformity of the expansion profile of the wires. We have shown that using soft metal gaskets can improve wire-electrode contact significantly over typical weighted contacts. Images of wire expansion profile and wire plasma emission will be presented for single and double wire shots on a 16 kA, 100 kV 4-stage Marx bank with 150 ns risetime. Bench resistance measurements for aluminum, stainless steel, and tungsten wires with diameters ranging from 7.5 um to 30 um will be presented. These measurements utilized both soft metal gasket contacts (gaskets include: indium, silver, aluminum, tin, and lead) and double-ended wire weight contacts (weights ranged from 0.4 g to 1.9 g). *This research was supported by U. S. DoE through Sandia National Laboratories award document numbers 240985, 768225, 790791 and 805234 to the University of Michigan. MRG supported by NNSA Fellowship and JCZ supported by NPSC Fellowship sponsored by Sandia National Labs.

  11. Seismic isolation of nuclear power plants using elastomeric bearings

    Kumar, Manish

    Seismic isolation using low damping rubber (LDR) and lead-rubber (LR) bearings is a viable strategy for mitigating the effects of extreme earthquake shaking on safety-related nuclear structures. Although seismic isolation has been deployed in nuclear structures in France and South Africa, it has not seen widespread use because of limited new build nuclear construction in the past 30 years and a lack of guidelines, codes and standards for the analysis, design and construction of isolation systems specific to nuclear structures. The nuclear accident at Fukushima Daiichi in March 2011 has led the nuclear community to consider seismic isolation for new large light water and small modular reactors to withstand the effects of extreme earthquakes. The mechanical properties of LDR and LR bearings are not expected to change substantially in design basis shaking. However, under shaking more intense than design basis, the properties of the lead cores in lead-rubber bearings may degrade due to heating associated with energy dissipation, some bearings in an isolation system may experience net tension, and the compression and tension stiffness may be affected by the horizontal displacement of the isolation system. The effects of intra-earthquake changes in mechanical properties on the response of base-isolated nuclear power plants (NPPs) were investigated using an advanced numerical model of a lead-rubber bearing that has been verified and validated, and implemented in OpenSees and ABAQUS. A series of experiments were conducted at University at Buffalo to characterize the behavior of elastomeric bearings in tension. The test data was used to validate a phenomenological model of an elastomeric bearing in tension. The value of three times the shear modulus of rubber in elastomeric bearing was found to be a reasonable estimate of the cavitation stress of a bearing. The sequence of loading did not change the behavior of an elastomeric bearing under cyclic tension, and there was no

  12. Damage of Elastomeric Matrix Composites (EMC-rubbers) Under Static Loading Conditions: Experimental and Numerical Study

    Ayari, F.; Bayraktar, E.; Zghal, A.

    2011-01-01

    Elastomeric matrix composites (EMC-rubbers) are considered as isotropic hyper elastic incompressible materials under static loading conditions. As a rubber material element cannot be extended to an infinite stretch ratio, a damage mechanism at large strain is considered. The phenomenon of cavitation plays an important role in the damage of EMCs and influences the toughening mechanism of rubber-modified plastics. Indeed, cavitation in elastomers is thought to be initiated from flaws, which grow primarily due to a hydrostatic tensile stress and ahead of the crack; there will not only be a high stress perpendicular to the plane of the crack but also significant stress components in the other direction. However, there exists historically much discussion on the evolution of the cavitation in elastomers under monotonic and/or static solicitation. Mainly, cavitation instability occurs when the stress levels are sufficiently high so that the void expansion rate becomes infinitely large. Many research works have been performed to understand the effects of rubber cavitation on toughening of plastics. In fact, the cavitation phenomenon is not well known in detail. The most popular idea states that the cavitation is related to the existence of the gas bubbles trapped in the material during the production stage and the growing of the cavities would then be the result of the growing gas bubbles. Further, instable failure mechanism at the end of the cavitation is not well known too.

  13. Damage of Elastomeric Matrix Composites (EMC-rubbers) Under Static Loading Conditions: Experimental and Numerical Study

    Elastomeric matrix composites (EMC-rubbers) are considered as isotropic hyper elastic incompressible materials under static loading conditions. As a rubber material element cannot be extended to an infinite stretch ratio, a damage mechanism at large strain is considered. The phenomenon of cavitation plays an important role in the damage of EMCs and influences the toughening mechanism of rubber-modified plastics. Indeed, cavitation in elastomers is thought to be initiated from flaws, which grow primarily due to a hydrostatic tensile stress and ahead of the crack; there will not only be a high stress perpendicular to the plane of the crack but also significant stress components in the other direction. However, there exists historically much discussion on the evolution of the cavitation in elastomers under monotonic and/or static solicitation. Mainly, cavitation instability occurs when the stress levels are sufficiently high so that the void expansion rate becomes infinitely large. Many research works have been performed to understand the effects of rubber cavitation on toughening of plastics. In fact, the cavitation phenomenon is not well known in detail. The most popular idea states that the cavitation is related to the existence of the gas bubbles trapped in the material during the production stage and the growing of the cavities would then be the result of the growing gas bubbles. Further, instable failure mechanism at the end of the cavitation is not well known too.

  14. Ultraviolet light crosslinking of poly(trimethylene carbonate) for elastomeric tissue engineering scaffolds

    Bat, Erhan; Kothman, Bas H. M.; Higuera, Gustavo A.; van Blitterswijk, Clemens A.; Feijen, Jan; Grijpma, Dirk W.

    2010-01-01

    A practical method of photocrosslinking high molecular weight poly(trimethylene carbonate)(PTMC) is presented. Flexible, elastomeric and biodegradable networks could be readily prepared by UV irradiating PTMC films containing pentaerythritol triacrylate (PETA) and a photoinitiator. The network chara

  15. Biodegradable, Elastomeric, and Intrinsically Photoluminescent Poly(Silicon-Citrates) with high Photostability and Biocompatibility for Tissue Regeneration and Bioimaging.

    Du, Yuzhang; Xue, Yumeng; Ma, Peter X; Chen, Xiaofeng; Lei, Bo

    2016-02-01

    Biodegradable polymer biomaterials with intrinsical photoluminescent properties have attracted much interest, due to their potential advantages for tissue regeneration and noninvasive bioimaging. However, few of current biodegradable polymers possess tunable intrinsically fluorescent properties, such as high photostability, fluorescent lifetime, and quantum field, and strong mechanical properties for meeting the requirements of biomedical applications. Here, by a facile one-step thermal polymerization, elastomeric poly(silicone-citrate) (PSC) hybrid polymers are developed with controlled biodegradability and mechanical properties, tunable inherent fluorescent emission (up to 600 nm), high photostability (beyond 180 min for UV and six months for natural light), fluorescent lifetime (near 10 ns) and quantum yield (16%-35%), high cellular biocompatibility, and minimal inflammatory response in vivo, which provide advantages over conventional fluorescent dyes, quantum dots, and current fluorescent polymers. The promising applications of PSC hybrids for cell and implants imaging in vitro and in vivo are successfully demonstrated. The development of elastomeric PSC polymer may provide a new strategy in synthesizing new inorganic-organic hybrid photo-luminescent materials for tissue regeneration and bioimaging applications. PMID:26687865

  16. Elastomeric Structural Attachment Concepts for Aircraft Flap Noise Reduction - Challenges and Approaches to Hyperelastic Structural Modeling and Analysis

    Sreekantamurthy, Thammaiah; Turner, Travis L.; Moore, James B.; Su, Ji

    2014-01-01

    Airframe noise is a significant part of the overall noise of transport aircraft during the approach and landing phases of flight. Airframe noise reduction is currently emphasized under the Environmentally Responsible Aviation (ERA) and Fixed Wing (FW) Project goals of NASA. A promising concept for trailing-edge-flap noise reduction is a flexible structural element or link that connects the side edges of the deployable flap to the adjacent main-wing structure. The proposed solution is distinguished by minimization of the span-wise extent of the structural link, thereby minimizing the aerodynamic load on the link structure at the expense of increased deformation requirement. Development of such a flexible structural link necessitated application of hyperelastic materials, atypical structural configurations and novel interface hardware. The resulting highly-deformable structural concept was termed the FLEXible Side Edge Link (FLEXSEL) concept. Prediction of atypical elastomeric deformation responses from detailed structural analysis was essential for evaluating feasible concepts that met the design constraints. The focus of this paper is to describe the many challenges encountered with hyperelastic finite element modeling and the nonlinear structural analysis of evolving FLEXSEL concepts. Detailed herein is the nonlinear analysis of FLEXSEL concepts that emerged during the project which include solid-section, foamcore, hollow, extended-span and pre-stressed concepts. Coupon-level analysis performed on elastomeric interface joints, which form a part of the FLEXSEL topology development, are also presented.

  17. Thermoviscoplastic behaviors of anisotropic shape memory elastomeric composites for cold programmed non-affine shape change

    Mao, Yiqi; Robertson, Jaimee M.; Mu, Xiaoming; Mather, Patrick T.; Jerry Qi, H.

    2015-12-01

    Shape memory polymers (SMPs) can fix a temporary shape and recover their permanent shape upon activation by an external stimulus. Most SMPs require programming at above their transition temperatures, normally well above the room temperature. In addition, most SMPs are programmed into shapes that are affine to the high temperature deformation. Recently, a cold-programmed anisotropic shape memory elastomeric composite was developed and showed interesting low temperature stretching induced shape memory behavior. There, simple, uniaxial stretching at low temperature transformed the composites into curled temporary shapes upon unloading. The exact geometry of the curled state depended on the microstructure of the composite, and the curled shape showed no affinity to the deformed shape. Heating the sample recovered the sample back to its original shape. This new composite consisted of an elastomeric matrix reinforced by aligned amorphous polymer fibers. By utilizing the plastic-like behavior of the amorphous polymer phase at low temperatures, a temporary shape could be fixed upon unloading since the induced plastic-like strain resists the recovery of the elastomer matrix. After heating to a high temperature, the permanent shape was recovered when the amorphous polymer softened and the elastomer matrix contracted. To set a theoretical foundation for capturing the cold-programmed shape memory effects and the dramatic non-affine shape change of this composite, a 3D anisotropic thermoviscoelastic constitutive model is developed in this paper. In this model, the matrix is modeled as a hyperelastic solid, and the amorphous phase of the fibrous mat is considered as a nonlinear thermoviscoplastic solid, whose viscous flow resistance is sensitive to both temperature and stress. The plastic-deformation like behavior demonstrated in the fiber is treated as nonlinear viscoplasticity with extremely high viscosity or long relaxation time at zero-stress state at low temperature. The

  18. Influence of elastomeric seal plate surface chemistry on interface integrity in biofouling-prone systems: Evaluation of a hydrophobic "easy-release" silicone-epoxy coating for maintaining water seal integrity of a sliding neoprene/steel interface

    Andolina, Vincent L.

    The scientific hypothesis of this work is that modulation of the properties of hard materials to exhibit abrasion-reducing and low-energy surfaces will extend the functional lifetimes of elastomeric seals pressed against them in abrasive underwater systems. The initial motivation of this work was to correct a problem noted in the leaking of seals at major hydropower generating facilities subject to fouling by abrasive zebra mussel shells and extensive corrosion. Similar biofouling-influenced problems can develop at seals in medical devices and appliances from regulators in anesthetic machines and SCUBA diving oxygen supply units to autoclave door seals, injection syringe gaskets, medical pumps, drug delivery components, and feeding devices, as well as in food handling equipment like pasteurizers and transfer lines. Maritime and many other heavy industrial seal interfaces could also benefit from this coating system. Little prior work has been done to elucidate the relationship of seal plate surface properties to the friction and wear of elastomeric seals during sliding contacts of these articulating materials, or to examine the secondary influence of mineralized debris within the contacting interfaces. This investigation utilized the seal materials relevant to the hydropower application---neoprene elastomer against carbon steel---with and without the application of a silicone-epoxy coating (WearlonRTM 2020.98) selected for its wear-resistance, hydrophobicity, and "easy-release" capabilities against biological fouling debris present in actual field use. Analytical techniques applied to these materials before and after wear-producing processes included comprehensive Contact Angle measurements for Critical Surface Tension (CA-CST) determination, Scanning Electron Microscopic inspections, together with Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-Ray Fluorescence (XRF) measurements for determination of surface texture and inorganic composition, Multiple

  19. Reaction Model of Gasket Sealing Systems%垫片密封失效反应论模型

    陈永林; 顾伯勤

    2001-01-01

    提出了垫片密封系统寿命,即有效使用时间的概念,将反应论模型应用于垫片密封系统,建立了系统失效模型,得到了泄漏率与时间的函数关系以及密封系统寿命的数学表达式。%lhe concept of the life span or the efficient time of gasket sealing systems is put forward.According to the reaction model, the failure model of gasket sealing systems is set up. The relation between the leakage and the time is obtained, and the formula of predicting the life span of gasket sealing systems is derived in this paper.

  20. Stress Wave Reflecting Attenuation to Improve Anti-shock Capacity by Gasket%垫片提高抗冲击能力的应力波衰减机理

    徐蓬朝; 黄惠东; 张龙山; 周平; 许冉

    2012-01-01

    Most of researches on anti-shock for penetrating fuze suggests that elasto-plastic gasket materials can be used because of their properties of cushion and energy-absorption. But the theory of cushion can hardly explain that why the gasket can improve fuze parts anti-shock capacity. In this paper, stress wave attenuating by gasket was regarded as the major factor of anti-shock. The large percentage of stress wave was reflected at fuze-shell/gasket interface. The gasket had few effects on acceleration but significant on attenuating fluctuation of stress wave. The simulation results indicateed that (1) the less of the impedance, the better of attenuation; (2) the thickness of the gaskets had few effects on attenuations (3)multilayer different gaskets were much better.%引信零部件抗高过载冲击,目前大多文献和资料提到用弹塑性垫片材料进行缓冲、吸能,但是缓冲理论并不能解释垫片提高引信零部件耐高过载能力.为此,提出垫片提高引信零部件抗冲击能力的机理主要是应力波反射衰减,即机械滤波.根据应力波在不同界面的反射与透射理论,冲击应力波在通过结构件与垫片的分界面时,因大部分被反射而衰减,垫片提高被保护件抗冲击能力的主要原因不是弹性缓冲,而是机械滤波;垫片对于被保护件质心惯性加速度影响很小,却能显著衰减骑在质心加速度曲线上的应力波,降低二者的合力尖峰,并减少往复振动冲击的破坏.仿真表明:垫片滤波说比缓冲说更合理,并且,波阻抗越小的垫片,机械滤波效果越好;只要远小于有效缓冲厚度,垫片厚度对机械滤波贡献不大;使用不同材料的两层垫片优于同厚度的单一材质垫片,多层更好.

  1. Star Coloring of Sierpi(n)ski Gasket Graphs%Sierpi(n)ski Gasket图的星着色

    潘玉美; 莫明忠

    2011-01-01

    In this paper, star coloring of Sierpi(n)ski gasket graphs Sn is studied.Meanwhile, it proved that S3 is uniquely 4-star-colorable up to isomorphism, and gave the exact star chromatic number of Sierpi(n)ski gasket Graphs: xs(Sn) =5 (n≥4).%研究了Sierpi(n)ski gasket图Sn的星着色,证明了在同构意义下S3是唯一的4-星可着色的,且给出了Sierp(n)ski gasket图Sn的星色数的精确值为Xs(Sn)=5(n≥4).

  2. Elastomeric fluorescent POF for partial discharge detection: recent progress

    Siebler, Daniel; Hohberg, Michaela; Rohwetter, Philipp; Brusenbach, Roy; Plath, Ronald

    2015-09-01

    We present recent progress in our development of fibre-optic sensors for the detection of partial discharge (PD) in silicone cable accessories, based on detecting related low-level optical emission. We experimentally show that the sensitive optical detection of PD can dramatically enhance the performance of conventional electrical PD measurement in electromagnetically noisy environments, and that it can yield high sensitivity and specificity even when no synchronous electrical PD measurement is conducted. This is demonstrated using a real-scale model of a high voltage cable accessory with a surface-attached conventional thermoplastic fluorescent polymer optical fibre (F-POF) sensor. In order to increase light collection efficiency, as a prerequisite for a commercially competitive implementation using cost-efficient detectors, sensing fibres will have to be integrated into the silicone rubber insulation, close to the potential origin of PD-induced damage. This is the rationale for our efforts to develop elastomeric fluorescent sensing fibres, tailored to the requirements of the application. We discuss specific challenges to be tackled and report on the successful implementation of all-silicone rubber fluorescent POF, to our best knowledge for the first time.

  3. Fabrication and characterization of heparin-grafted poly-L-lactic acid-chitosan core-shell nanofibers scaffold for vascular gasket.

    Wang, Ting; Ji, Xuyuan; Jin, Lin; Feng, Zhangqi; Wu, Jinghang; Zheng, Jie; Wang, Hongyin; Xu, Zhe-Wu; Guo, Lingling; He, Nongyue

    2013-05-01

    Electrospun nanofibers were widely studied to be applied as potential materials for tissue engineering. A new technology to make poly-l-lactic acid/chitosan core/shell nanofibers from heterologous solution by coaxial electrospinning technique was designed for vascular gasket. Chitosan surface was cross-linked by genipin and modified by heparin. Different ratios of PLA/CS in heterologous solution were studied to optimize the surface morphology of fibers. Clean core-shell structures formed with a PLA/CS ratio at 1:3. Superior biocompatibility and mechanical properties were obtained by optimizing the core-shell structure morphology and surface cross-linking of chitosan. UE7T-13 cells grew well on the core-shell structure fibers as indicated by methylthiazolyldiphenyl-tetrazolium bromide (MTT) results and scanning electron microscopy (SEM) images. Compared with the pure PLA fiber meshes and commercial vascular patch, PLA/CS core-shell fibers had better mechanical strength. The elastic modulus was as high as 117.18 MPa, even though the yield stress of the fibers was lower than that of the commercial vascular patch. Attachment of red blood cell on the fibers was evaluated by blood anticoagulation experiments and in vitro blood flow experiments. The activated partial thromboplastin time (APTT) and prothrombin time (PT) value from PLA/CS nanofibers were significantly longer than that of pure PLA fibers. SEM images indicated there were hardly any red blood cells attached to the fibers with chitosan coating and heparin modification. This type of fiber mesh could potentially be used as vascular gasket. PMID:23586670

  4. Flange-Gasket Sealing of Petrichemical Engineering%石油化工装置法兰密封垫片探讨

    冯文清

    2014-01-01

    The flange-gasket sealing theory was analyzed , and influencing effects were discussed , such as gasket performance , the flange form and rigidity , bolts retightening force , installation error , and operation conditions.Different kinds of gasket structure and sealing effect , such as nonmetal -gasket , half metal -gasket and metal gasket were compared , and every kind of gasket by structure and operation conditions were analyzed and compared , and the right selection and installation method was proposed.%分析了垫片的密封机理,从垫片的性能、法兰密封面形式及刚度、螺栓预紧力、安装误差、操作条件等方面讨论了影响垫片密封的因素。对比了目前实用较为广泛的非金属垫片、半金属垫片和金属垫片三种不同类型垫片的结构形式和密封性能,并对每种垫片的具体实用类型从结构到操作条件进行了对比分析,归纳了一般情况下密封垫片的选型方法和正确的安装方法。

  5. Measurement of oil film thickness for application to elastomeric Stirling engine rod seals

    Krauter, A. I.

    1981-01-01

    The rod seal in the Stirling engine has the function of separating high pressure gas from low or ambient pressure oil. An experimental apparatus was designed to measure the oil film thickness distribution for an elastomeric seal in a reciprocating application. Tests were conducted on commercial elastomeric seals having a 76 mm rod and a 3.8 mm axial width. Test conditions included 70 and 90 seal durometers, a sliding velocity of 0.8 m/sec, and a zero pressure gradient across the seal. An acrylic cylinder and a typical synthetic base automotive lubricant were used. The experimental results showed that the effect of seal hardness on the oil film thickness is considerable. A comparison between analytical and experimental oil film profiles for an elastomeric seal during relatively high speed reciprocating motion showed an overall qualitative agreement.

  6. Thermally tailored gradient topography surface on elastomeric thin films.

    Roy, Sudeshna; Bhandaru, Nandini; Das, Ritopa; Harikrishnan, G; Mukherjee, Rabibrata

    2014-05-14

    We report a simple method for creating a nanopatterned surface with continuous variation in feature height on an elastomeric thin film. The technique is based on imprinting the surface of a film of thermo-curable elastomer (Sylgard 184), which has continuous variation in cross-linking density introduced by means of differential heating. This results in variation of viscoelasticity across the length of the surface and the film exhibits differential partial relaxation after imprinting with a flexible stamp and subjecting it to an externally applied stress for a transient duration. An intrinsic perfect negative replica of the stamp pattern is initially created over the entire film surface as long as the external force remains active. After the external force is withdrawn, there is partial relaxation of the applied stresses, which is manifested as reduction in amplitude of the imprinted features. Due to the spatial viscoelasticity gradient, the extent of stress relaxation induced feature height reduction varies across the length of the film (L), resulting in a surface with a gradient topography with progressively varying feature heights (hF). The steepness of the gradient can be controlled by varying the temperature gradient as well as the duration of precuring of the film prior to imprinting. The method has also been utilized for fabricating wettability gradient surfaces using a high aspect ratio biomimetic stamp. The use of a flexible stamp allows the technique to be extended for creating a gradient topography on nonplanar surfaces as well. We also show that the gradient surfaces with regular structures can be used in combinatorial studies related to pattern directed dewetting. PMID:24697617

  7. Analysis and Design of Cylinder Head Gasket Sealing under Transient Thermal Cycles%瞬态温度循环下的气缸垫密封分析与设计

    潘琼瑶; 冉帆

    2016-01-01

    针对气缸垫易于失效的受载和瞬态温度循环工况,提出了瞬态温度循环下的气缸垫密封设计与分析方法.采用材料和接触非线性有限元方法建立缸体、缸盖、气缸垫和螺栓一体化分析模型,进行瞬态温度和结构密封分析,采用密封压力和凸筋跳跃量对气缸垫密封进行评价.通过分析,识别出密封压力和凸筋跳跃量存在风险的区域,对设计进行改进,合理设置停止片高度,做到密封压力和凸筋跳跃量之间的平衡.%For the failure loading and transient thermal cycle of head gasket ,the design and analysis methods of sealing were put forward .The integrated analysis model of block ,head ,gasket and bolts was built with the material and contact nonlinear finite element analysis method and the analysis of transient temperature and structural sealing was conducted .The sealing per-formance of head gasket was finally evaluated with the sealing pressure and convex rib height .According to the analysis re-sults ,the potential failure areas of sealing pressure and convex rib height were identified and the design was improved to realize the balance of both .

  8. Elastomeric Properties of Poly(glycerol sebacate) (PGS) Based Nanoparticle Composites

    Chung, Hyun-Joong; Li, Xinda; Hong, Albert T.-L.

    2014-03-01

    Owing to the unique combination of biocompatible, biodegradable, and elastomeric properties, poly(glycerol sebacate) and their derivatives are an emerging class of biomaterials for soft tissue replacement, drug delivery, tissue adhesive, and hard tissue regeneration. The mechanical properties of the polyester have been tailored to match a wide range of target organs, ranging from cardiac muscle to bones, by manipulating the process parameters to modulate cross-linking density. In the present study, we applied nanoparticles and cross-linking agents to further optimize their elastomeric properties. Especially, the study aims to enhance the practically important, but less studied, property of tear resistance. Microscopic origin of the property enhancement is discussed.

  9. 制冷设备用非石棉密封垫片的分析研究%Analysis of Refrigeration Equipment with Non-asbestos Gasket

    邱传惠; 杨书益

    2014-01-01

    The performance characteristics of gaskets used in refrigeration equipment was analyzed , focusing on the refrigeration equipment used in non-asbestos gasket tested performance analysis , refrigeration equipment for use on standard gasket made some modifications recommendations .%分析了制冷设备中常用的一些密封垫片的性能特点,重点对制冷设备中使用的非石棉垫片进行了试验性能的分析,对制冷设备上使用的密封垫片标准提出了一些修改建议。

  10. Analysis of Flange Installation Requirements for Spiral- wound Gasket%缠绕式垫片法兰接头装配要求的剖析

    任建民; 蔡仁良

    2001-01-01

    Based on the application practice of the spiral- wound gasket flange joint and complied with the requirements for spiral- wound gasket in ASME B16.20, the installation requirements for the spiral- wound gasket used in the connection of the low pressure piping flanges was analyzed in this paper.%本文根据缠绕垫片法兰接头的实际情况,按照 ASME B16.20缠绕式垫片的技术要求,对低压管法兰用缠绕式垫片的安装要求进行一些分析。

  11. A fundamental study of the modification of elastomeric poly(dimethylsiloxane) and silicon surfaces using polymers and their applications in patterning

    Ell, John Randall

    A fundamental study of the polymer functionalization of flat elastomeric poly(dimethylsiloxane) (PDMS) and Silcon wafers is described. Using polymer grafting methodologies such as "grafting onto" and "grafting from" a functional substrate, the development of a novel pattern miniaturization protocol and method for nanoparticle patterning was achieved. Currently, a general strategy for the poly(ethylene glycol) (PEG) functionalization of Silastic RTV elastomeric substrates does not exist in the literature. Our preliminary attempts with the functionalization of elastomeric PDMS suffered from a lack of effective surface functionalization control, primarily as a result of literature inconsistencies and inadequate surface characterization. Therefore, we performed in-depth and quantitative surface analysis of the surface functionality of the elastic PDMS substrates that were used to adopt a modified functionalization strategy. The end result was the development of a dynamic material where the surface energy could be manipulated through simple mechanical stretching. A new miniaturization protocol, referred to as high-efficiency stepwise contraction and adsorption nanolithography (hSCAN), was demonstrated. A thin film of elastomeric precursor was first cast on a stretched substrate. A designed microstructure was then imprinted and the precursor layer was subsequently cured. The microstructure was miniaturized after the substrate relaxed to its original length. The miniaturized structures can be used as stamps to transfer materials onto a designated support or as molds to produce the structure on another stretched substrate for further miniaturization. The patterning of materials by microcontact printing has been improved with the development of hSCAN. Optical disc media polycarbonate discs were used as master molds in the hSCAN miniaturization protocol with promising results. CD's, DVD's and even Blue-ray polycarbonate discs were miniaturized, and techniques, we developed a

  12. Comparison of frictional resistance between self-ligating and conventional brackets tied with elastomeric and metal ligature in orthodontic archwires

    Vanessa Vieira Leite

    2014-06-01

    Full Text Available OBJECTIVE: To compare the frictional resistance between self-ligating and conventional brackets tied to different types of wire. MATERIAL AND METHODS : Abzil Kirium Capelozza (Pattern I and Easy Clip (Roth prescription incisor brackets were used. An elastomeric ligature or a ligating wire 0.10-in was used to ligate the wire to the Abzil bracket. Three types of orthodontic archwire alloys were assessed: 0.016-in NiTi wire, 0.016 x 0.021-in NiTi wire and 0.019 x 0.025-in steel wire. Ten observations were carried out for each bracket-archwire angulation combination. Brackets were mounted in a special appliance, positioned at 90 degrees in relation to the wire and tested in two angulations. Frictional test was performed in a Universal Testing Machine at 5 mm/min and 10 mm of displacement. The means (MPa were submitted to ANOVA and Tukey's test set at 5% of significance. The surfaces of wires and brackets were observed at SEM. RESULTS: Steel-tied brackets (16.48 ± 8.31 showed higher means of frictional resistance than elastomeric-tied brackets (4.29 ± 2.16 and self-ligating brackets (1.66 ± 1.57 (P 0.05. No statistical differences (P > 0.05 were found between zero (7.76 ± 8.46 and five-degree (7.19 ± 7.93 angulations. CONCLUSIONS: Friction was influenced not only by the type of bracket, but also by the ligating systems. Different morphological aspects were observed for the brackets and wires studied

  13. Comparison of frictional resistance between self-ligating and conventional brackets tied with elastomeric and metal ligature in orthodontic archwires

    Leite, Vanessa Vieira; Lopes, Murilo Baena; Gonini Júnior, Alcides; de Almeida, Marcio Rodrigues; Moura, Sandra Kiss; de Almeida, Renato Rodrigues

    2014-01-01

    Objective To compare the frictional resistance between self-ligating and conventional brackets tied to different types of wire. Material and Methods Abzil Kirium Capelozza (Pattern I) and Easy Clip (Roth prescription) incisor brackets were used. An elastomeric ligature or a ligating wire 0.10-in was used to ligate the wire to the Abzil bracket. Three types of orthodontic archwire alloys were assessed: 0.016-in NiTi wire, 0.016 x 0.021-in NiTi wire and 0.019 x 0.025-in steel wire. Ten observations were carried out for each bracket-archwire angulation combination. Brackets were mounted in a special appliance, positioned at 90 degrees in relation to the wire and tested in two angulations. Frictional test was performed in a Universal Testing Machine at 5 mm/min and 10 mm of displacement. The means (MPa) were submitted to ANOVA and Tukey's test set at 5% of significance. The surfaces of wires and brackets were observed at SEM. Results Steel-tied brackets (16.48 ± 8.31) showed higher means of frictional resistance than elastomeric-tied brackets (4.29 ± 2.16 ) and self-ligating brackets (1.66 ± 1.57) (P 0.05). No statistical differences (P > 0.05) were found between zero (7.76 ± 8.46) and five-degree (7.19 ± 7.93) angulations. Conclusions Friction was influenced not only by the type of bracket, but also by the ligating systems. Different morphological aspects were observed for the brackets and wires studied PMID:25162575

  14. Radiation Effects on Polymer Properties

    Bouquet, F. L.; Winslow, J. W.

    1987-01-01

    Report compiles data on effects of radiation on physical properties of synthetic organic materials. Emphasis on materials of interest to nuclear-equipment and nuclear-reactor designers. Data covers five categories of polymeric materials: Insulators, elastomeric seals and gaskets, lubricants, adhesives, and coatings. More than 250 materials represented.

  15. Artificial Neural Network Analysis of Sierpinski Gasket Fractal Antenna: A Low Cost Alternative to Experimentation

    Balwinder S. Dhaliwal

    2013-01-01

    Full Text Available Artificial neural networks due to their general-purpose nature are used to solve problems in diverse fields. Artificial neural networks (ANNs are very useful for fractal antenna analysis as the development of mathematical models of such antennas is very difficult due to complex shapes and geometries. As such empirical approach doing experiments is costly and time consuming, in this paper, application of artificial neural networks analysis is presented taking the Sierpinski gasket fractal antenna as an example. The performance of three different types of networks is evaluated and the best network for this type of applications has been proposed. The comparison of ANN results with experimental results validates that this technique is an alternative to experimental analysis. This low cost method of antenna analysis will be very useful to understand various aspects of fractal antennas.

  16. Modified Sierpinski Gasket Patch Antenna for UMTS and 2.4/5.2 WLAN

    Y. E. Ali

    2013-05-01

    Full Text Available A modified Sierpinski Gasket fractal antenna for multiband application is proposed in this paper. The modified ground plane and the microstrip feed are used to obtain the wider bandwidth at the resonance frequency. The antenna is designed and printed on two layers FR-4 substrate (ϵr=4.4 and h=1.6 mm to cover the UMTS and 2.4/5.2 WLAN. The radiation pattern of the proposed antenna is similar to an omnidirectional. The proposed antenna has maximum gain of 1.88, 1.6, 4.31 dB at 2, 2.4, 5.2 GHz, respectively The properties of the antenna such as return losses, radiation pattern, input resistance and gain are determined via numerical CST Microwave Studio 2010 software.

  17. Experimental and numerical study of damage initiation mechanism in elastomeric composites

    T.D. Silva Botelho

    2009-09-01

    Full Text Available Purpose: Experimental and Finite Element Analysis (FEA of the damage initiation mechanisms in elastomeric composites were carried out under static loading at room temperature. Double Cantilever Beam (DCB specimens from natural rubber (NR vulcanised and reinforced with other materials such as carbon black, silica, fibres and textiles or metals (rubber composites.Design/methodology/approach: Very huge experimental results were compared with that of the Finite Element Analysis (FEA. Damage mechanism has been described with a threshold criterion to identify damage. The damage was evaluated just at the beginning of the tearing by assuming large strain. A typical type of specimen geometry of Double Cantilever Beam (DCB specimens was considered under static tensile tests conducted on the notched specimens with variable depths.Findings: In this stage of this research, a finite element analysis (FEA has been applied under the same conditions of this part in order to obtain the agreement between experimental and FEA results. The numerical modelling is a representation of a previous experimental study. The specimen is stretched more than once its initial size, so that large strains occur. A hyper elastic Moonley-Rivlin law and a Griffith criterion are chosen. The finite elements analysis was performed with ABAQUS code (V.6.4.4.Practical implications: A damage criterion was suggested in the case of simple tension conditions by assuming large strain levels. an effective finite elements model has been developed to evaluate notch size effects on the load-displacement elastic response of 3D-DCB type specimen.Originality/value: This study proposes a threshold criterion for the damage just at the beginning of the tearing for Double Cantilever Beam (DCB specimens from rubber composites and gives a detail discussion for explaining the damage mechanisms. Comparison of FEA results with those of experimental studies gives many facilities for the sake of simplicity in

  18. Encyclopedia of polymer science and engineering, Vol. 11: Photographic applications to polyesters, elastomeric

    Mark, H.F.; Bikales, N.; Overberger, C.G.; Menges, G.

    1987-01-01

    The contents of this book are: Photographic Applications; Photocrosslinking; Phthaloccyanine Polymers; Pipe; Plant Design; Plasma Polymerizaton; Plastic; Plasticizers; Plastics; Identification; Plastics, Processing; Polyacetals; Poly(alkylidene sulfides); Polyalkylidenes; Polyamides; Polyamides, Aromatic; Polyamides, Fibers; Polyamides, Plastics; Polyamides from Fatty Acids; Polyamides; Polyaminotriazoles; Polyampholtyes; Polyanhydrides; Poly(arylene sulfides); Polybenzimidazoles; Polybenzothiazoles; Polybenzoxazinones; Polybithiazoles; Polycarbonates; Polyelectrolytes; Polyesters, Polyesters, Aromatic; Polyesters, Containers; and Polyesters, Elastomeric.

  19. Experimental Study on Influence of Mechanical Vibration during Transport of Transport/Storage Cask for Spent Nuclear Fuel on Containment Performance of Metal Gasket during Storage in Japan

    Transport casks of spent nuclear fuel will receive mechanical vibration during transport. It is known that the containment performance of metal gaskets is influenced by large external load or displacement. Quantitative influence of such vibration during transport on the containment performance of the metal gasket has not been known, but is crucial information particularly if the cask is stored as it is after the transport

  20. In vitro evaluation of force degradation of elastomeric chains used in Orthodontics

    André Weissheimer

    2013-02-01

    Full Text Available OBJECTIVE: To analyze the in vitro force degradation of four different brands of elastomeric chains: American Orthodontics, Morelli, Ormco and TP Orthodontics. METHODS: The sample consisted of 80 gray elastomeric chains that were divided into four groups according to their respective manufacturers. Chain stretching was standardized at 21 mm with initial force release ranging from 300 g to 370 g. The samples were kept in artificial saliva at a constant temperature of 37°C and the degradation force was recorded at the following time intervals: initial, 1, 3, 5, 7 and 9 hours, and 1, 7, 14, 21, 28, and 35 days. RESULTS: There was a statistically significant difference between the groups regarding the force degradation, mainly within the first day, as a force loss of 50-55% was observed during that time in relation to the initial force. The force delivered at 35 days ranged from 122 g to 148 g. CONCLUSION: All groups showed force degradation over time, regardless of their trademarks, a force loss of 59-69% was observed in the first hour compared to baseline. However, because the variation in force degradation depends on the trademark, studies such as the present one are important for guiding the clinical use of these materials.OBJETIVO: analisar, in vitro, a degradação de força, ao longo do tempo, de elastômeros das marcas comerciais American Orthodontics, Morelli, Ormco e TP Orthodontics. MÉTODOS: a amostra constituiu-se de 80 segmentos de elastômeros em cadeia fechada na cor cinza, divididos em quatro grupos, conforme o fabricante. A distensão foi padronizada em 21mm, com liberação de força inicial variando de 300 a 370g de força. As amostras foram mantidas em saliva artificial em temperatura constante de 37ºC, e a força avaliada nos seguintes intervalos: inicial, 1h, 3h, 5h, 7h, 9h, 1 dia, 7 dias, 14 dias, 21 dias, 28 dias e 35 dias. RESULTADOS: houve diferença estatisticamente significativa na degradação de força entre os

  1. 关于透镜垫密封形式的探讨%Inquire into Seal Form of Lens Gasket

    张恒

    2015-01-01

    针对透镜垫密封形式的分歧,对透镜垫的密封系统进行分析和计算,并与标准中的计算结果相互比较和验证。结果表明,透镜垫的密封形式应属于强制密封,但也具有一定的自紧作用;由于其自紧力很小,几乎无法对其结构尺寸进行更优化的设计。%In connection with differences of lens gasket seal forms,analysis and calculation are carried out of the seal system of lens gasket,the calculation results are compared and verified with that of the standard.The results show that seal form of the lens gasket belongs to forced seal,but it has certain self-tightening effect;because its self-tightening force is very small,it is almost impossible to perform optimal design of its structure size.

  2. Technology of Fluid Sealing Glue Gasket in Engine%发动机液态密封垫片技术

    邢东仕

    2013-01-01

    The paper mainly introduced the applying technology of fluid sealant gasket, including the characteristic of fluid sealant gasket, the different sealant selection, the designing requirement of flange, the coating technics of fluid sealant, finally, the applying status of fluid sealant in engine was introduced. Through the introduction of liquid sealing sealant technology, the paper provided the guide suggestion to the fluid gasket.%对液态密封垫片应用技术进行了详细介绍,主要涉及液态密封垫片的特点、不同类型液态密封胶的选择、法兰面的设计要求、液态密封胶的施工工艺等,最后对液态密封胶在发动机上的应用做了简单概述.通过液态对密封胶技术的介绍,为液态密封胶的正确使用提供了指导性意见.

  3. Novel elastomeric fibrous networks produced from poly(xylitol sebacate)2:5 by core/shell electrospinning: fabrication and mechanical properties.

    Li, Yuan; Thouas, George A; Chen, Qizhi

    2014-12-01

    Fabrication of nonlinear elastic materials that resemble biological tissues remains a challenge in biomaterials research. Here, a new fabrication protocol to produce elastomeric fibrous scaffolds was established, using the core/shell electrospinning technique. A prepolymer of poly(xylitol sebacate) with a 2:5mol ratio of xylitol:sebacic acid (PXS2:5) was first formulated, then co-electrospun with polyvinyl alcohol (PVA - 95,000Mw). After cross-linking of core polymer PXS2:5, the PVA shells were rinsed off in water, leaving a porous elastomeric network of PXS2:5 fibres. Under aqueous conditions, the PXS2:5 fibrous scaffolds exhibited stable, nonlinear J-shaped stress-strain curves, with large average rupture elongation (76%) and Young׳s modulus (~1.0MPa), which were in the range of muscle tissue. Rupture elongation of PXS2:5 was also much higher when electrospun, compared to 2D solid sheets (45%). In direct contact with cell monolayers under physiological conditions, PXS2:5 scaffolds were as biocompatible as those made of poly-l-lactic acid (PLLA), with improvements over culture medium alone. In conclusion, the newly developed porous PXS2:5 scaffolds show tissue-like mechanical properties and excellent biocompatibility, making them very promising for bioengineering of soft tissues and organs. PMID:25243671

  4. DISPOSABLE NON-MECHANICAL ELASTOMERIC BALLOON PUMP FOR CONTINUOUS EPIDURAL INFUSION: AN EFFECTIVE AND RELIABLE MEANS FOR POSTOPERATIVE ANALGESIA

    Dilip Kumar; Mrinal Kanti; Subhankar

    2016-01-01

    Postoperative pain an unpleasant sensory and emotional experience is one of the most challenging and gratifying domains to treat. Aim is here to assess effectiveness of postoperative pain relief, side effects and complications while using non-mechanical disposable elastomeric pump as continuous epidural infusion. PATIENTS AND METHODS The present study has been carried out on thirty patients in postoperative wards. At the end of operation the Elastomeric pump containin...

  5. Study of the hydro-mechanical behaviour of expanded graphite gaskets

    The poro-mechanical behaviour models developed by O. Coussy permit to consider various phenomena observed experimentally: thermo-hydro-mechanical couplings, plasticity, etc. The aim of this study is to implement the simplest poro-mechanical model (i.e. the isotropic linear poro-elastic model) to model the gasket hydro-mechanical behaviour. First, isotropic poro-elastic characteristics of expanded graphite have been estimated from these tests conducted at Departement Mecanique et Technologie des Composants (MTC) and data from literature. Then, analytical solutions of the tightness tests developed at the MTC Department have been carried out. These calculations provide a first estimation of porosity variations during a tightness tests with metal/metal contact or in elastic recovery, and during a 'hot thermal transient'. Thickness controlled numerical calculations have proved the analytical calculations relevance. With regard to simulation of tests with metal/metal contact or 'hot thermal transient', stress controlled numerical calculations have pointed out: - a greater vertical displacement on the inner side of the graphite ring and - a z dependence of the radial displacement and thus a porous differential variation between the upper and lower faces of the ring. (author)

  6. Analysis and experiment research on sealing gasket for a automobile motor igniting coil%发动机点火线圈密封垫密封性试验与计算研究∗

    郝伟

    2015-01-01

    Based on the large-scale finite element software ABAQUS,the sealing performance of the sealing gasket for an automo-bile motor igniting coil was researched. The procedure for establishing the two-dimensional axisymmetric finite element model of automobile motor igniting coil sealing gasket was elaborated. The contact pressure, Von. Mises and anti-off performance were cal-culated,the simulation results testified that the sealing gasket meet the conditions of sealing gasket-designing in sealing perform-ance and strength as well as anti-off performance. Static surface pressure test was conducted. The results proved that the finite ele-ment simulation model is correct by making a comparison between the simulation results and test results. Some factors influencing maximum contact pressure and Von. Mises of sealing face were taken into account,such as height compression ratio,rubber mate-rial parameters and friction coefficient. The results indicate that with the increase of height compression ratio,the sealing perform-ance improved significantly. Height compression ratio and rubber hardness also affect Von. Mises of sealing gasket. The rubber hardness parameters have a little influence on contact pressure.%利用大型有限元仿真计算软件ABAQUS对某款发动机点火线圈密封垫的密封性能进行研究。详细阐述了点火线圈密封垫二维轴对称有限元模型的建立过程,对密封垫密封面处的接触压力、密封垫的Von. Mises应力与脱落力进行计算,仿真计算结果证明该密封垫满足密封性、强度与防脱性设计要求。对密封垫进行了静态面压试验,试验结果与仿真计算结果吻合较好,验证了有限元数值方法的合理性。探讨了密封垫高度压缩率、橡胶材料参数对最大接触压力与Von. Mises应力的影响。计算分析表明:密封垫的高度压缩率越大,密封效果越好;Von. Mises应力随着高度压缩率与橡胶材料硬度的增大而增大

  7. The effect of nonlinear elastomeric lag damper characteristics on helicopter rotor dynamics

    Felker, Fort F.; Lau, Benton H.; Mclaughlin, Stacey; Johnson, Wayne

    1987-01-01

    Many helicopters use elastomeric lag dampers to prevent ground resonance and aeromechanical instability in hover and forward flight. Recent experimental results have shown that when the damper motion occurs at two superimposed frequencies, which is characteristic of operation in forward flight, the damper properties are not well-predicted by a superposition of the damper properties at each of the motion frequencies. This paper presents experimental data obtained with an elastomeric damper while it was undergoing single- and dual-frequency motion. The effect of the nonlinear dual-frequency damper characteristics on predicted rotor aeromechanical stability in forward-flight operation in a wind tunnel was evaluated using the comprehensive rotorcraft analysis program called CAMRAD.

  8. Increasing pumping efficiency in a micro throttle pump by enhancing displacement amplification in an elastomeric substrate

    Fluid transport is accomplished in a micro throttle pump (MTP) by alternating deformation of a micro channel cast into a polydimethylsiloxane (PDMS) elastomeric substrate. The active deformation is achieved using a bimorph PZT piezoelectric disc actuator bonded to a glass diaphragm. The bimorph PZT deflects the diaphragm as well as alternately pushing and pulling the elastomer layer providing displacement amplification in the PDMS directly surrounding the micro channel. In order to improve pumping rates we have embedded a polymethylmethacrylate (PMMA) ring into the PMDS substrate which increases the magnitude of the displacement amplification achieved. FEM simulation of the elastomeric substrate deformation predicts that the inclusion of the PMMA ring should increase the channel deformation. We experimentally demonstrate that inclusion of a PMMA ring, having a diameter equal to that of the circular node of the PZT/glass/PDMS composite, increases in the throttle resistance ratio by 40% and the maximum pumping rate by 90% compared to an MTP with no ring.

  9. A simple scanning spectrometer based on a stretchable elastomeric reflective grating

    Ghisleri, C.; Milani, P., E-mail: paolo.milani@mi.infn.it [CIMAINA and Dipartimento di Fisica, Università di Milano, via Celoria 16, 20133 Milano (Italy); WISE srl, Piazza Duse 2, 20122 Milano (Italy); Potenza, M. A. C.; Bellacicca, A. [CIMAINA and Dipartimento di Fisica, Università di Milano, via Celoria 16, 20133 Milano (Italy); Ravagnan, L. [WISE srl, Piazza Duse 2, 20122 Milano (Italy)

    2014-02-10

    We report a scanning optical spectrometer based on the use of a stretchable elastomeric reflective grating. The grating is obtained by supersonic cluster beam implantation of silver nanoparticles on polydimethylsiloxane previously grooved by molding to create a replica of a commercial digital versatile disk grating. The use of a stretchable grating allows the spectrometer spanning the whole optical wavelength range by solely extending the diffraction element by more than 100% of its original dimensions. The stretchable reflective optical grating shows excellent performances and stability upon thousands of stretching cycles. The use of this elastomeric element makes the optical layout and the mechanics of the spectrometer extremely simple and advantageous for those applications where spectral resolution is not a major requirement. As a proof of principle, we present the absorption spectrum of Rhodamine B in solution obtained by our spectrometer and compared to commercial instruments.

  10. A simple scanning spectrometer based on a stretchable elastomeric reflective grating

    We report a scanning optical spectrometer based on the use of a stretchable elastomeric reflective grating. The grating is obtained by supersonic cluster beam implantation of silver nanoparticles on polydimethylsiloxane previously grooved by molding to create a replica of a commercial digital versatile disk grating. The use of a stretchable grating allows the spectrometer spanning the whole optical wavelength range by solely extending the diffraction element by more than 100% of its original dimensions. The stretchable reflective optical grating shows excellent performances and stability upon thousands of stretching cycles. The use of this elastomeric element makes the optical layout and the mechanics of the spectrometer extremely simple and advantageous for those applications where spectral resolution is not a major requirement. As a proof of principle, we present the absorption spectrum of Rhodamine B in solution obtained by our spectrometer and compared to commercial instruments

  11. Increasing pumping efficiency in a micro throttle pump by enhancing displacement amplification in an elastomeric substrate

    Fujiwara, T.; Johnston, I. D.; Tracey, M. C.; Tan, C. K. L.

    2010-06-01

    Fluid transport is accomplished in a micro throttle pump (MTP) by alternating deformation of a micro channel cast into a polydimethylsiloxane (PDMS) elastomeric substrate. The active deformation is achieved using a bimorph PZT piezoelectric disc actuator bonded to a glass diaphragm. The bimorph PZT deflects the diaphragm as well as alternately pushing and pulling the elastomer layer providing displacement amplification in the PDMS directly surrounding the micro channel. In order to improve pumping rates we have embedded a polymethylmethacrylate (PMMA) ring into the PMDS substrate which increases the magnitude of the displacement amplification achieved. FEM simulation of the elastomeric substrate deformation predicts that the inclusion of the PMMA ring should increase the channel deformation. We experimentally demonstrate that inclusion of a PMMA ring, having a diameter equal to that of the circular node of the PZT/glass/PDMS composite, increases in the throttle resistance ratio by 40% and the maximum pumping rate by 90% compared to an MTP with no ring.

  12. Regional anaesthesia elastomeric pump performance after a single use and subsequent refill: a laboratory study.

    Grant, C R K; Fredrickson, M J

    2009-07-01

    Ambulatory local anaesthetic delivery systems are often limited by a short effective duration of infusion. Prolonging nerve blockade by substituting a new pump as recommended by the manufacturers, represents a substantial consumable item cost ($US 300-500). We therefore evaluated the flow delivery performance of 31 single model elastomeric devices (all with a 2 ml.h(-1) background and 5 ml every hour bolus capability) that had been filled, used in clinical practice and then refilled in the laboratory. For the second infusion, there was a pattern of over-infusion (pumps depreciated to pumps was not only within safe limits, but also predominantly within the range (background infusion +/- 15%, bolus +10/-20%) specified by the manufacturer for primary infusion. We conclude that this elastomeric regional anaesthesia pump design performs satisfactorily after having been refilled following a single previous use. PMID:19624633

  13. Pattern transfer printing by kinetic control of adhesion to an elastomeric stamp

    Nuzzo, Ralph G.; Rogers, John A.; Menard, Etienne; Lee, Keon Jae; Khang, Dahl-Young; Sun, Yugang; Meitl, Matthew; Zhu, Zhengtao

    2011-05-17

    The present invention provides methods, systems and system components for transferring, assembling and integrating features and arrays of features having selected nanosized and/or microsized physical dimensions, shapes and spatial orientations. Methods of the present invention utilize principles of `soft adhesion` to guide the transfer, assembly and/or integration of features, such as printable semiconductor elements or other components of electronic devices. Methods of the present invention are useful for transferring features from a donor substrate to the transfer surface of an elastomeric transfer device and, optionally, from the transfer surface of an elastomeric transfer device to the receiving surface of a receiving substrate. The present methods and systems provide highly efficient, registered transfer of features and arrays of features, such as printable semiconductor element, in a concerted manner that maintains the relative spatial orientations of transferred features.

  14. Roll to plate printed stretchable silver electrode using single walled carbon nanotube on elastomeric substrate.

    Jung, Minhun; Noh, Jinsoo; Kim, Junseok; Kim, Donghwan; Cho, Gyoujin

    2013-08-01

    Stretchable electronics may open new applications in display, sensors and actuators. To attain the stretchable electronics, the ink formulation should be compatible with elastomeric substrates. Here, we present the formulation of silver nanoparticles and single walled carbon nanotubes (SWNTs) for printing stretchable silver electrodes on the elastomeric substrates. Highly conductive stretchable electrodes can be printed directly on the poly(styrene-b-butadiene-b-styrene) (PSBS) substrates by roll to plate (R2P) gravure printer. During the stretching test, R2P printed silver based stretchable electrodes show the high conductivity of 1000 S cm(-1) at 0.27 wt% of SWNT loading. Furthermore, the resistance of the printed silver electrode was not changed up to 15% of tensile strain. PMID:23882805

  15. 3D Structural Patterns in Scalable, Elastomeric Scaffolds Guide Engineered Tissue Architecture

    Kolewe, Martin E.; Park, Hyoungshin; Gray, Caprice; Ye, Xiaofeng; Langer, Robert; Freed, Lisa E.

    2013-01-01

    Microfabricated elastomeric scaffolds with 3D structural patterns are created by semi-automated layer-by-layer assembly of planar polymer sheets with through-pores. The meso-scale interconnected pore architectures governed by the relative alignment of layers are shown to direct cell and muscle-like fiber orientation in both skeletal and cardiac muscle, enabling scale up of tissue constructs towards clinically relevant dimensions.

  16. Applicability of base isolation made of elastomeric isolators for the protection of cultural heritage

    Vojko Kilar; David Koren; Simon Petrovčič

    2009-01-01

    This article briefly presents the applicability of base isolation made of elastomeric isolators for the protection of heritage architecture. The first part of the article gives an illustrative overview on the use of base isolation throughout the world, together with an analysis of guidelines for the protection and management of places of heritage architecture. The guidelines which are given through international agreements and resolutions on the conservation of monuments have to be considered...

  17. Evaluation of the susceptibility to pigmentation of orthodontic esthetic elastomeric ligatures

    Janine Soares Cavalcante; Marcelo de Castellucci e Barbosa; Marcio Costa Sobral

    2013-01-01

    OBJECTIVE: The purpose of this laboratory study was to evaluate changes in the pigmentation of esthetic elastomeric ligatures after immersion in a staining solution. METHODS: Sixty ligatures were selected and divided into 12 groups according to their brand and also considering their condition, i.e., unstretched or stretched. The groups were divided into: Morelli (clear), TP Orthodontics (clear), American Orthodontics (clear), 3M/Unitek (clear), American Orthodontics (pearl color) and 3M/Unite...

  18. Evaluation of the susceptibility to pigmentation of orthodontic esthetic elastomeric ligatures

    Janine Soares Cavalcante

    2013-04-01

    Full Text Available OBJECTIVE: The purpose of this laboratory study was to evaluate changes in the pigmentation of esthetic elastomeric ligatures after immersion in a staining solution. METHODS: Sixty ligatures were selected and divided into 12 groups according to their brand and also considering their condition, i.e., unstretched or stretched. The groups were divided into: Morelli (clear, TP Orthodontics (clear, American Orthodontics (clear, 3M/Unitek (clear, American Orthodontics (pearl color and 3M/Unitek (pearl color, separated into groups of 5 unstretched and five stretched ligatures. Assessment of their color changes was performed by means of digital photograph and computer analysis using Adobe Photoshop. Standardized digital photographs were taken at T0 (before the staining process, with unstretched ligatures and at T1 (following the 5-days staining process. The staining solution was composed of artificial saliva and foods with staining potential. At T1 the ligatures were either stretched or unstretched. RESULTS: The results of this study showed that esthetic elastomeric ligatures are prone to staining. Among the evaluated brands, TP Orthodontics and American Orthodontics clear ligatures were the most stable. Moreover, 3M/Unitek pearl ligatures demonstrated statistically significant changes in all variables. CONCLUSIONS: Esthetic elastomeric ligatures are susceptible to staining and no statistically significant difference was found between unstretched or stretched ligatures, with the sole exception of the TP Orthodontics brand. The 3M/Unitek's pearl color ligatures displayed the greatest staining potential.

  19. Investigation of the recycling of tires to elastomeric requirements by techniques of thermal compression

    Nadal Gisbert, Antonio V.

    In this work is investigated the recycling of tires to elastomeric requirements by thermal compression. The production of recycled products is carried out starting from the powder, of elastomeric nature, coming from the grinding of used tires denominated GTR (Ground Tire Rubber) of different grain size, although the fundamental objective is the recycling of powder of 0,2mm grain size. The process of forming used for obtaining the recycled product is thermal compression, due to its simplicity and low cost. The composition of the powder has been analyzed and also the influence, on the elastomeric characteristics of the recycled product, of different parameters: Grain size, compact pressure, temperature, time, thickness of the recycled product and combination of sizes. At last we give an hypothesis that justifies the mechanism that gives cohesion to the powder GTR and allows their recycling. We also have carried out an analysis of the investigation lines, at the present, on the recycling of tires in general and an economic study of the viability of the recycled product in front of present products in the market, agglomerated with polyurethane, that have their application in using it in different types of floors.

  20. 非石棉纤维橡胶垫片失效分析%Failure Analysis of Non-Asbestos Fiber-Reinforced Elastomer Gasket

    陆晓峰; 顾伯勤; 丁毅; 夏翔鸣; 朱瑞松

    2001-01-01

    The leakage event of a non-asbestos gasket was taken place at the manhole flanged joint of a boiler after more than one-year service.In order to find out the reason of this accident,the spot investigation and gasket performance test were carried out,and the microstructure of some new and failure gaskets was observed by means of scanning electron microscope.The research results indicate that hydrolysis and pulverization of non-asbestos fibers of the gasket caused by steam at the elevated temperature is the main reason resulted in the gasket failure.%一台废热锅炉人孔用非石棉纤维橡胶垫片服役一年多后发生泄漏。通过现场调查和新旧垫片性能对比试验,并在扫描电镜下观察分析了垫片基体和纤维材料的微观组织,发现垫片失效主要是由其内部的增强纤维材料在高温蒸汽下水解、粉化导致强度明显下降而引起的。

  1. Fracture mechanics and statistical mechanics of reinforced elastomeric blends

    Heinrich, Gert; Kaliske, Michael; Klüppel, Manfred; Schneider, Konrad; Vilgis, Thomas

    2013-01-01

    Elastomers are found in many applications ranging from technology to daily life applications for example in tires, drive systems, sealings and print rollers. Dynamical operation conditions put extremely high demands on the performance and stability of these materials and their elastic and flow properties can be easily adjusted by simple manipulations on their elastic and viscous properties. However, the required service life suffers often from material damage as a result of wear processes such as abrasion and wear fatigue, mostly caused by crack formation and propagation. This book covers interdisciplinary research between physics, physical chemistry, material sciences and engineering of elastomers within the range from nanometres to millimetres and connects these aspects with the constitutive material properties. The different chapters describe reliable lifetime and durability predictions based on new fracture mechanical testing concepts and advanced material-theoretical methods which are finally implemented...

  2. Evaluation of the influence of the polymer-filler interaction on compounds based on epoxidized elastomeric matrix and precipitated silica

    Tatiana L. A. C. Rocha

    2006-06-01

    Full Text Available The introduction of epoxy groups into the main chain of elastomers has emerged as a promising alternative, considering the monitoring of polymer-filler interaction leading to changes in the properties of vulcanizates. The epoxidation reaction (in situ was chosen to modify elastomers, such as polybutadiene (BR and copolymer of styrene-butadiene-rubber (SBR, because it is a simple, easily controlled reaction, even considering the small epoxidation degree. The modification degree of the polymeric chain was studied with FT-IR and ¹H-NMR. The shift of the Tg to high temperatures with the increase of the epoxy group in the polymer chain was monitored through differential scanning calorimetry (DSC. An analysis of the dynamic modulus of the material in relation to its dependence on the amplitude and temperature was carried out. The interaction between epoxidized elastomeric matrix and silica as filler was extremely improved, even in the presence of very low content of epoxy groups into the polymer chain.

  3. Results from the University of Leipzig project concerning the long-term stability of elastomeric building sealants

    Boettger, T.; Bolte, H. [Univ. of Leipzig (Germany). Arbeitsgruppe Dauerbestaendigkeit von Baustoffen

    1998-12-31

    A comprehensive multi-year durability study was undertaken in which a series of high-performance sealant products were artificially and naturally aged in an effort to determine test methods most likely to simulate in-service conditions. Sixteen elastomeric products were evaluated; fourteen were sealants based on either polysulfide, polyurethane, or silicone compounds. The remaining products, an ethylene-propylene-diene-monomer rubber and a polychloroprene, were used to compare ageing effects on rubbery compounds subjected to ageing effects. Both free-film and model joint compounds were tested. Artificial ageing was conducted using different weathering apparatus and consisted of various combinations of exposure to fluorescent or xenon lamp ultraviolet radiation, simultaneous heat ageing at temperatures ranging from 60 to 140 C, and water condensation or spray. Natural ageing took place on a site located near the test laboratories and was characterized by its temperate climate and industrial setting. Changes in materials properties were characterized through mechanical tests, thermo-analytical methods, and chemical spectroscopy. Results from specimens aged artificially were compared with those aged from five years of open air weathering in Leipzig. As well, results on model joints were compared with those obtained from testing free films. Preliminary results suggest that the research should continue such that a comprehensive assessment of different ageing regimes and their effects on various sealant products can be ascertained. This work would then provide a fundamental basis for developing useful and predictive assessment tests for sealant products currently in use.

  4. Theoretical Analysis of Fractal Leakage Model for Nonmetallic Gasket%非金属垫片分形泄漏模型理论分析

    周先军

    2011-01-01

    以分形几何为基础,建立非金属质垫片分形泄漏模型.研究表明,载荷稳定时垫片中压力分布呈幂律变化,垫片泄漏率与压差成正比,且与分形垫片参数、异常扩散系数等有关.%Based on fractal geometry, a fractal leakage model for nonmetallic gasket was established. The results indicate that the pressure on gaskets varies in power law at a steady load, and its leakage rate varies with differential pressure and relates to gasket specifications and anomalous diffusion coefficient, etc.

  5. Qualitative Analysis of Gradient-Type Systems with Oscillatory Nonlinearities on the Sierpi(n)ski Gasket

    Gabriele BONANNO; Giovanni MOLICA BISCI; Vicentiu R(A)DULESCU

    2013-01-01

    Under an appropriate oscillating behavior either at zero or at infinity of the nonlinear data,the existence of a sequence of weak solutions for parametric quasilinear systems of the gradient-type on the Sierpi(n)ski gasket is proved.Moreover,by adopting the same hypotheses on the potential and in presence of suitable small perturbations,the same conclusion is achieved.The approach is based on variational methods and on certain analytic and geometrical properties of the Sierpi(n)ski fractal as,for instance,a compact embedding result due to Fukushima and Shima.

  6. Towards a stripline setup to characterise the effects of corrosion and ageing on the shielding effectiveness of EMI gaskets

    Pissoort, Davy; Catrysse, Johan; Claeys, Tim; Vanhee, Filip; Boesman, Bart; Brull, Christian

    2015-01-01

    This paper introduces a novel measurement set-up dedicated to the characterization of the evolution of the high-frequency shielding-effectiveness of gaskets due to corrosion and ageing. The measurement set-up is based on the recently introduced stripline set-up which has been validated previously up to 40 GHz. Compared to the original stripline set-up, the adapted set-up has a removable “clamping module” which can be easily mounted and removed from the set-up. The clamping module allows to ag...

  7. 4040A型喷油器垫片分选控制系统的设计%Design of 4040A Injector Gasket Sorting Control System

    石剑锋

    2013-01-01

    Injector gasket sorting is related to the quality of the injector. Traditional gasket sorting is labor-intensive work. To reduce work intensity, we designed 4040A injector gasket sorting control system. In this paper, we use PLC as control system. The simulation of the opening pressure is controlled through the servo motor; and during exercise we measured injector assembly and the rear thimble assembly length, and then chose proper gaskets. The paper introduces the working process of the gasket sorting machine and the implementation method. Practice shows that this system has achieved the expected goal in that it can measure and sort gasket automatically.%喷油器垫片分选关系到喷油器产品的品质,传统垫片分选需大量工人进行人工分选,属于劳动密集型工作,为降低工人的劳动强度,设计了4040A型喷油器垫片分选控制系统。分选机采用PLC作为主控系统,通过伺服电机控制模拟压力,在运动过程中测量喷油体组件和后顶针组件的长度,再经计算选出合适的垫片;同时介绍了垫片分选机的工作过程、实现方法等。运行结果表明,该控制系统能实现自动测量、自动选取垫片的功能,达到预期效果。

  8. Containment of fluid samples in the hydrothermal diamond-anvil cell without the use of metal gaskets: Performance and advantages for in situ analysis

    Chou, I.-Ming; Bassett, William A.; Anderson, Alan J.; Mayanovic, Robert A.; Shang, L.

    2008-01-01

    Metal gaskets (Re, Ir, Inconel, or stainless steel) normally used to contain fluid samples in the hydrothermal diamond-anvil cell (HDAC) are sometimes undesirable due to possible contamination and to gasket deformation at high pressures and temperatures resulting in nonisochoric behavior. Furthermore, in x-ray spectroscopic experiments, metal gaskets may attenuate the incident x-ray beam and emitted fluorescence x-rays, and the interaction of scattered radiation with the gasket may produce fluorescence that interferes with the x-ray spectrum of the sample. New arrangements and procedures were tested for the operation of the HDAC without using the metal gaskets. Distilled, de-ionized water was loaded into the sample chamber, a laser-milled recess 300 ??m in diameter and ???50 ??m deep centered in the 1.0 mm face of the lower diamond anvil, and sealed by pressing the top diamond anvil face directly against the lower one without a metal gasket in between. A maximum sample pressure of 202 MPa at 617 ??C was maintained for a duration of 10 min without evidence of leakage. A small change in fluid density was observed in one experiment where the sample was held at 266 MPa at 708 ??C for 10 min. The gasketless HDAC was also employed in x-ray absorption spectroscopy experiments, where, in addition to the sample chamber in the lower diamond, two grooves were milled at a 90?? angle to each other around the sample chamber to minimize the attenuation of incident and fluorescent x rays. With a minimum distance between the sample chamber and the grooves of 80 ??m, a pressure of 76 MPa at 500 ??C was maintained for 2 h with no change in the original fluid density. ?? 2008 American Institute of Physics.

  9. A family of self-avoiding random walks interpolating the loop-erased random walk and a self-avoiding walk on the Sierpinski gasket

    Hattori, Kumiko; Ogo, Noriaki; Otsuka, Takafumi

    2015-01-01

    We show that the `erasing-larger-loops-first' (ELLF) method, which was first introduced for erasing loops from the simple random walk on the Sierpinski gasket, does work also for non-Markov random walks, in particular, self-repelling walks to construct a new family of self-avoiding walks on the Sierpinski gasket. The one-parameter family constructed in this method continuously connects the loop-erased random walk and a self-avoiding walk which has the same asymptotic behavior as the `standard...

  10. Graded manufacturing technique of graphite spiral wound gaskets%石墨缠绕垫片分级制造技术

    周先军; 仇性启

    2001-01-01

    在研究缠绕垫片的力学性能与其结构及工艺参数关系的基础上,提出了缠绕垫片的分级制造技术,已取得初步研究成果。%A graded manufacturing technique of the graphite spiral wound gaskets was raised, based on the research of the relationship between graphite spiral wound gasket's mechanical performance and its structure, producing technology parameters. The research had acquired primary fruit.

  11. 估计Sierpinski地毯的Hausdorff测度的一个公式%An estimate of Hausdorff measure of Sierpinski gasket

    戴欣荣

    2001-01-01

    给出了一个估计Sierpinski地毯的Hausdorff测度的公式。由此公式,可以很容易得到Sierpinski地毯的Hausdorff测度的上界估计。%This paper gives a formula to estimate the upper bound of theHausdorff measure of the Sierpinski gasket. By this formula, one can get the upper bound of the Hausdorff measure of the Sierpinski gasket as well as possible, in case he finds a set well enough.

  12. Baseline and Lifetime Assessments for DC745U Elastomeric Components

    Maxwell, R S; Chinn, S C; Herberg, J; Harvey, C; Alviso, C; Vance, A; Cohenour, R; Wilson, M; Solyom, D

    2004-12-20

    The silicone elastomer Dow Corning DC 745U is used in two major components in the W80. We have investigated a number of issues concerning this material. Our studies have accomplished a baseline study of the chemical composition of DC745 and LLNL now has a good understanding of the chemical composition of this material. DC745 crystallizes within the system STS. Two potential means identified to mitigate the risk associated with this phenomenon are to (1) change material formulation and (2) predose the parts to {approx} 25 MRad {gamma}-radiation. A candidate material identified by Gordon Spellman has been studied for composition and the lack of crystallization within the STS has been verified. A sensitivity study of the effects of relevant aging mechanisms also has been performed. The extent of aging due to radiation exposure or elevated temperatures is minimal over the expected course of the LEP. In addition, since the DC745 parts are expected to be replaced at rebuild, the aging clock is essentially being reset. No significant aging issues seem likely to develop for these parts. DC745 parts are also subject to permanent deformation in service. Our studies have shown that the deformation is likely due to incomplete mixing of the raw gum stock and the curing agent at production. This results in areas of low crosslink density that are subject to a higher degree of compression set in service. We have identified two production diagnostic tools based on Nuclear Magnetic Resonance spectroscopy to prescreen the parts at production at KCP. These studies are concluded with specific recommendation for changes to core surveillance for this part based on the chemical knowledge we have gained from this study.

  13. Generation of the additional fluorescence radiation in the elastomeric shields used in computer tomography (CT)

    Two commercially available (EP, Z) and eight new elastomeric composites (M1-M4, G1-G4, of thickness ∼1 mm) containing mixtures of differing proportions of heavy metal additives (Bi, W, Gd and Sb) have been synthesised and examined as protective shields. The intensity of the X-ray fluorescence radiation generated in the typical elastomeric shields for CT, containing Bi and other heavy metal additives influence on the practical shielding properties. A method for assessing the radiation shielding properties of elastomeric composites used in CT examination procedures via X-ray spectrometry has been proposed. To measure the radiation reduction ability of the protective shields, the dose reduction factor (DRF) has been determined. The lead equivalents for the examined composites were within the ranges of 0.046-0.128 and 0.048-0.130 mm for 122.1 and 136.5 keV photons, respectively. The proposed method, unlike to the common approach, includes a dose contribution from the induced X-ray fluorescence radiation of the heavy metal elements in the protective shields. The results clearly indicate that among the examined compositions, the highest values DRF have been achieved with preparations containing Bi+W, Bi+W+Gd and Bi+W+Sb mixtures with gradually decreasing content of heavy metal additives in the following order: Bi, W, Gd and Sb. The respective values of DRF obtained for the investigated composites were 21, 28 and 27 % dose reduction for a 1 mm thick shield and 39 and ∼50 % for a 2 mm thick layer (M1-M4). (author)

  14. Modelling the self-assembly of elastomeric proteins provides insights into the evolution of their domain architectures.

    Hongyan Song

    Full Text Available Elastomeric proteins have evolved independently multiple times through evolution. Produced as monomers, they self-assemble into polymeric structures that impart properties of stretch and recoil. They are composed of an alternating domain architecture of elastomeric domains interspersed with cross-linking elements. While the former provide the elasticity as well as help drive the assembly process, the latter serve to stabilise the polymer. Changes in the number and arrangement of the elastomeric and cross-linking regions have been shown to significantly impact their assembly and mechanical properties. However, to date, such studies are relatively limited. Here we present a theoretical study that examines the impact of domain architecture on polymer assembly and integrity. At the core of this study is a novel simulation environment that uses a model of diffusion limited aggregation to simulate the self-assembly of rod-like particles with alternating domain architectures. Applying the model to different domain architectures, we generate a variety of aggregates which are subsequently analysed by graph-theoretic metrics to predict their structural integrity. Our results show that the relative length and number of elastomeric and cross-linking domains can significantly impact the morphology and structural integrity of the resultant polymeric structure. For example, the most highly connected polymers were those constructed from asymmetric rods consisting of relatively large cross-linking elements interspersed with smaller elastomeric domains. In addition to providing insights into the evolution of elastomeric proteins, simulations such as those presented here may prove valuable for the tuneable design of new molecules that may be exploited as useful biomaterials.

  15. Modelling the self-assembly of elastomeric proteins provides insights into the evolution of their domain architectures.

    Song, Hongyan; Parkinson, John

    2012-01-01

    Elastomeric proteins have evolved independently multiple times through evolution. Produced as monomers, they self-assemble into polymeric structures that impart properties of stretch and recoil. They are composed of an alternating domain architecture of elastomeric domains interspersed with cross-linking elements. While the former provide the elasticity as well as help drive the assembly process, the latter serve to stabilise the polymer. Changes in the number and arrangement of the elastomeric and cross-linking regions have been shown to significantly impact their assembly and mechanical properties. However, to date, such studies are relatively limited. Here we present a theoretical study that examines the impact of domain architecture on polymer assembly and integrity. At the core of this study is a novel simulation environment that uses a model of diffusion limited aggregation to simulate the self-assembly of rod-like particles with alternating domain architectures. Applying the model to different domain architectures, we generate a variety of aggregates which are subsequently analysed by graph-theoretic metrics to predict their structural integrity. Our results show that the relative length and number of elastomeric and cross-linking domains can significantly impact the morphology and structural integrity of the resultant polymeric structure. For example, the most highly connected polymers were those constructed from asymmetric rods consisting of relatively large cross-linking elements interspersed with smaller elastomeric domains. In addition to providing insights into the evolution of elastomeric proteins, simulations such as those presented here may prove valuable for the tuneable design of new molecules that may be exploited as useful biomaterials. PMID:22396636

  16. Prediction of service lifetimes of elastomeric seals during radiation ageing

    Measurements have been made on fluoropolymer seals of leakage rates, sealing force and compression set over a limited range of temperature and irradiation conditions to compare these techniques for their effectiveness in determining seal lifetimes. The results obtained indicate that the use of compression set tests in the routine assessment of seal performance is justified. Compression set measurements have been made on a polyurethane and a fluoropolymer over a range of temperature and radiation dose rates. The time-temperature superposition principle has been used to determine the thermal and dose rate shift factors asub(T), asub(R) and activation energy Esub(a) for both materials. Determination of the functional dependence of asub(T), asub(R) and Esub(a) on the dose rate enables realistic lifetime predictions to be made even when dose rate effects and temperature-radiation synergism are present. (orig.)

  17. Biodegradabilite et proprietes energetiques d'elastomeres azotures

    Lavoie, Jonathan

    The interest for polymer materials has steadily increased in the last decades and the use of polymer materials has been increasing ever since. These polymers are used in a vast range of applications from civil to military (Colclough et al., 1994; Nair & Laurencin, 2007; Sansone et al., 2012). This demand for polymer materials resulted in the development of various polymers with a wide range of properties depending on the desired application. In the field of propellants, this interest led to the development of glycidyl azide polymer (GAP) and other similar materials. Growing environmental concerns has led to a demand for more environmentally friendly polymers. This demand so far has been increasing and shows no sign of following a different trend for the next years. This demand is in part due to the presence of non-recyclable polymers, for which end of life can be problematic. At the same time, another problematic arose: the soil contamination originating from repeated military training as well as the subsequent contamination of water supplies by rain water seeping into the ground absorbing part of the contaminants (Dontsova, Pennington, Hayes, imunek, & Williford, 2009; M. R. Walsh, Thiboutot, Walsh, & Ampleman, 2012). This phenomenon incurs large decontamination costs and can result in the abandonment of training grounds due to contamination (Michael R. Walsh, Walsh, & Hewitt, 2010). The compounds responsible for the contamination of military training grounds are in part present in elastomers used as binders for propellants. The binders are non-biodegradable as well. In order to make greener propellants, it is not only necessary to replace the contaminants by non-contaminant materials, but also necessary to replace the binder by using new biodegradable materials. Glycidyl azide polymer, a commonly used energetic polymer in binders is non-biodebradable and as such unburned residue will accumulate in the environment. The main objective of this work is to develop new

  18. Comment on ``Critical behavior of the chain--generating function of self--avoiding walks on the Sierpinski gasket family: The Euclidean limit''

    Milosevic, Sava; Zivic, Ivan; Elezovic-Hadzic, Suncica

    1998-01-01

    We refute the claims made by Riera and Chalub [Phys.Rev.E {\\bf 58}, 4001 (1998)] by demonstrating that they have not provided enough data (requisite in their series expansion method) to draw reliable conclusions about criticality of self-avoiding walks on the Sierpinski gasket family of fractals.

  19. 广义Sierpinski垫片的Hausdorff测度的上限估值!%An estimation of the upper bound on the Hausdorff measure of the generalized Sierpinski gasket

    洪英辉

    2014-01-01

    通过构造一个一元序列和一个二元序列,得到了一个便于计算的广义 Sierpinski垫片的 Hausdorff测度的上限估值公式,该公式将文献[2]中关于经典的 Sierpinski垫片的 Hausdorff测度的上限估值的一个结果推广到所有维数大于1的广义 Sierpinski垫片的情形。%We obtained a formula regarding the upper bounds of the Hausdorff measure of the generalized Sierpinski gasket by constructing a 1-tuple sequence and a 2-tuple sequence.By means of this formula we can calculate some comparable different upper bounds of the generalized-Sierpinski gasket easily.This formula extends the result on upper bounds of the Hausdorff measure of the classical Sierpinski gasket in reference [2] to the case of the generalized Sierpinski gasket with the dimension larger than 1 .

  20. Finite element analysis on contact stress distribution of NiTi alloy sealing gasket%NiTi合金密封垫片压紧力分布有限元分析

    诸士春; 陆晓峰; 巩建鸣

    2012-01-01

    By using the ABAQUS method of finite element analysis, the contact stress distribution of NiTi shape memory alloy gasket was analyzed and compared with that of A1050 aluminum gasket and spirally wound gasket under the same loading conditions. Result showed that the uniformity of gasket contact stress distibution for NiTi shape memory alloy was better than that of the other two gaskets. Subjected to internal pressure and external bending moment, NiTi shape memory alloy gasket had better sealing performance than the other two gaskets.%利用ABAQUS有限元方法分析NiTi形状记忆合金密封面上的压紧力分布,并与同等加载条件下的A1050纯铝平垫、金属石墨缠绕垫片作比较.结果表明:NiTi形状记忆合金垫片密封面上压紧力分布均匀性优于后2种常规垫片;内压力和弯矩作用下,NiTi形状记忆合金密封面压紧力受载荷影响比后2种垫片小.

  1. Buckling of Dielectric Elastomeric Plates for Electrically Active Microfludic Pumps

    Holmes, Douglas; Tavakol, Behrouz; Bozlar, Michael; Froehlicher, Guillaume; Stone, Howard; Aksay, Ilhan

    2013-11-01

    Fluid flow can be directed and controlled by a variety of mechanisms within industrial and biological environments. Advances in microfluidic technology have required innovative ways to control fluid flow on a small scale, and the ability to actively control fluid flow within microfluidic devices is crucial for advancements in nanofluidics, biomedical fluidic devices, and digital microfluidics. In this work, we present a means for microfluidic control via the electrical actuation of thin, flexible valves within microfluidic channels. These structures consist of a dielectric elastomer confined between two compliant electrodes that can be actively and reversibly buckle out of plane to pump fluids from an applied voltage. The out-of-plane deformation can be quantified using two parameters: net change in surface area and the shape of deformation. Change in surface area depends on the voltage, while the deformation shape, which significantly affects the flow rate, is a function of voltage, and the pressure and volume of the chambers on each side of the thin plate. The use of solid electrodes enables a robust and reversible pumping mechanism that will have will enable advancements in rapid microfluidic diagnostics, adaptive materials, and artificial muscles.

  2. The effect of maximum stress located at gasket outer periphery on leakage of bolted flanged connections%垫片外缘最大应力对螺栓法兰连接结构泄漏率影响

    刘麟; 顾伯勤; 李传文

    2012-01-01

    螺栓法兰连接广泛的应用于石油化工等过程装备中,其是最重要的静密封连接形式之一,失效的主要原因是泄漏.利用有限元法对垫片的平均应力和外缘最大应力关系进行分析研究;采用解析方法预测螺栓法兰连接结构的泄漏率,并与试验结果进行对比,研究了垫片外缘最大应力与泄漏率之间的关系.结果表明,随着螺栓载荷的增加,法兰偏转程度增加,垫片平均应力与垫片外缘最大应力的差值逐渐增大;垫片外缘最大应力较平均应力对连接结构泄漏率影响更大.%The bolted flanged connection is one of the most important sealing connections in petrochemical industry,and leakage is the primary reason of the connections failure.The relationship between average gasket stress and maximum gasket stress located at the gasket outer periphery was analyzed by FEM methodAnd the leakage of bolted flanged connection was predicted,which results were investigated and compared with the experimental result.Then the effect of maximum gasket stress located at the gasket outer periphery on connection leakage was studied,which results indicate that the difference value of average gasket stress and maximum gasket stress increases gradually along with increasing of bolt loadThe maximum gasket stress located at the gasket outer periphery is found to be a key parameter that controls leakage.

  3. A new UV-curing elastomeric substrate for rapid prototyping of microfluidic devices

    Alvankarian, Jafar; Yeop Majlis, Burhanuddin

    2012-03-01

    Rapid prototyping in the design cycle of new microfluidic devices is very important for shortening time-to-market. Researchers are facing the challenge to explore new and suitable substrates with simple and efficient microfabrication techniques. In this paper, we introduce and characterize a UV-curing elastomeric polyurethane methacrylate (PUMA) for rapid prototyping of microfluidic devices. The swelling and solubility of PUMA in different chemicals is determined. Time-dependent measurements of water contact angle show that the native PUMA is hydrophilic without surface treatment. The current monitoring method is used for measurement of the electroosmotic flow mobility in the microchannels made from PUMA. The optical, physical, thermal and mechanical properties of PUMA are evaluated. The UV-lithography and molding process is used for making micropillars and deep channel microfluidic structures integrated to the supporting base layer. Spin coating is characterized for producing different layer thicknesses of PUMA resin. A device is fabricated and tested for examining the strength of different bonding techniques such as conformal, corona treating and semi-curing of two PUMA layers in microfluidic application and the results show that the bonding strengths are comparable to that of PDMS. We also report fabrication and testing of a three-layer multi inlet/outlet microfluidic device including a very effective fluidic interconnect for application demonstration of PUMA as a promising new substrate. A simple micro-device is developed and employed for observing the pressure deflection of membrane made from PUMA as a very effective elastomeric valve in microfluidic devices.

  4. Microrobotic tentacles with spiral bending capability based on shape-engineered elastomeric microtubes.

    Paek, Jungwook; Cho, Inho; Kim, Jaeyoun

    2015-01-01

    Microscale soft-robots hold great promise as safe handlers of delicate micro-objects but their wider adoption requires micro-actuators with greater efficiency and ease-of-fabrication. Here we present an elastomeric microtube-based pneumatic actuator that can be extended into a microrobotic tentacle. We establish a new, direct peeling-based technique for building long and thin, highly deformable microtubes and a semi-analytical model for their shape-engineering. Using them in combination, we amplify the microtube's pneumatically-driven bending into multi-turn inward spiraling. The resulting micro-tentacle exhibit spiraling with the final radius as small as ~185 μm and grabbing force of ~0.78 mN, rendering itself ideal for non-damaging manipulation of soft, fragile micro-objects. This spiraling tentacle-based grabbing modality, the direct peeling-enabled elastomeric microtube fabrication technique, and the concept of microtube shape-engineering are all unprecedented and will enrich the field of soft-robotics. PMID:26066664

  5. Experiment-Based Sensitivity Analysis of Scaled Carbon-Fiber-Reinforced Elastomeric Isolators in Bonded Applications

    Farshad Hedayati Dezfuli

    2016-01-01

    Full Text Available Fiber-reinforced elastomeric isolators (FREIs are a new type of elastomeric base isolation systems. Producing FREIs in the form of long laminated pads and cutting them to the required size significantly reduces the time and cost of the manufacturing process. Due to the lack of adequate information on the performance of FREIs in bonded applications, the goal of this study is to assess the performance sensitivity of 1/4-scale carbon-FREIs based on the experimental tests. The scaled carbon-FREIs are manufactured using a fast cold-vulcanization process. The effect of several factors including the vertical pressure, the lateral cyclic rate, the number of rubber layers, and the thickness of carbon fiber-reinforced layers are explored on the cyclic behavior of rubber bearings. Results show that the effect of vertical pressure on the lateral response of base isolators is negligible. However, decreasing the cyclic loading rate increases the lateral flexibility and the damping capacity. Additionally, carbon fiber-reinforced layers can be considered as a minor source of energy dissipation.

  6. Frictional resistance of orthodontic wires tied with 3 types of elastomeric ligatures

    Amanda Carneiro da Cunha

    2011-12-01

    Full Text Available The aims of this study were to determine and compare frictional resistance obtained by low-friction and conventional elastomeric ligatures in the presence of artificial saliva, and observe whether this variable changed after 21 days. Super Slick® low-friction elastomeric ligatures and conventional ligatures of the brands TP conventional® and Unitek® were placed on standard edgewise maxillary central incisor metal brackets, slot .022" × .028" tying rectangular orthodontic wires .018" × .025". Three experimental groups were arranged according to the type of ligature and a control group in which no wires were used. The friction values obtained between the bracket/wire/ligature set were measured using a Universal Test Machine at a speed of 20 mm/minute, at two experimental time intervals: T0 - immediately after specimen fabrication; and T1 - 21 days after fabrication and immersion in artificial saliva at 37 ºC. Conventional Unitek ligatures and the low-friction ligature (Super Slick showed the lowest friction values at T0. After 21 days (T1, however, conventional Unitek ligatures presented the lowest value. All groups assessed from T0 to T1 showed a numerical reduction in friction values, suggesting that time, heat and humidity may cause elastic degradation, however this was not verified statistically (P > 0.05.

  7. Optical fiber sensor for pressure measurement based on elastomeric membrane and macrobending loss

    Ribeiro, Livia A.; Rosolem, Joao B.; Dini, Danilo C.; Floridia, Claudio; Bezerra, Edson W.; Cezar, Fabio A.; Loichate, Marcelo D.; Durelli, Anderson S.

    2012-04-01

    We propose a fiber optic sensor array based on bend loss assessed by optical time domain reflectometry (OTDR). The sensor mechanism is based on optical fiber bending loss compressed by external pressure. An elastomeric surface is applied to the sensor in order to communicate external pressure to the fiber coil and also, this make sensor able to deal with degradation coming from aggressive environments. The sensing system proposed is able to monitor liquid or gas pressure in different environments, such as water, oil, alcohols, some diluted acids and others, depending only of elastomeric membrane choice. In order to protect the sensor stage against environmental degradation a plastic packaging was chosen. Bend loss measurements is taken concerning the number of fiber loops involved in the sensor, pump signal wavelength and temporal width. This long for the best parameters in the sensor construction. The specific case of the sensor applied to water percolation monitoring from embankment damns is detailed in this paper; for this application the sensor array have a number of at least six stages totally independent each other, in such a way that each stage can be developed to monitor a specific environment. Sensors have shown good performance in field tests, reaching work range from 0.1 to 0.6 atm with 0.05 atm of precision.

  8. Applicability of base isolation made of elastomeric isolators for the protection of cultural heritage

    Vojko Kilar

    2009-01-01

    Full Text Available This article briefly presents the applicability of base isolation made of elastomeric isolators for the protection of heritage architecture. The first part of the article gives an illustrative overview on the use of base isolation throughout the world, together with an analysis of guidelines for the protection and management of places of heritage architecture. The guidelines which are given through international agreements and resolutions on the conservation of monuments have to be considered when designing the base isolation of existing monuments. Generally, interventions into such structures should be minimal or visible as little as possible and should minimally affect the aesthetics and functionality of the object. In the second part of the article the general and some special requirements for base isolation design with elastomeric isolators are presented. The influence of the slenderness of the structure is analysed in more detail. The analysis is based on the corresponding rocking prevention criterion, upon the condition that the isolators cannot bear any tensile forces. The article concludes with a presentation of the maximum height-to-width ratios for objects that can be mounted on isolators, fulfilling the given rocking prevention criterion for different soil conditions. The maximum aspect ratios have also been determined by considering 5 appropriately scaled ground motions from the 1998 Posočje earthquake.

  9. Dynamic Response of a System under Anti-Vibration Forced Regime Depending on the Settlement Angle of the Elastomeric Isolators

    Carmen Alexandru

    2013-09-01

    Full Text Available For a number N of elastomeric elements grouped in parallel, but mounted at an angle alpha between the compression axis and the vertical axis, the total stiffness should be assessed accordingly. The vibration transmissibility will be determined for two borderline cases, so that intermediate values can be evaluated for an anti-vibration isolation techniques solution

  10. 垫片密封的可靠性分析方法%Reliability Analysis Method of Gasket Sealing

    陈永林; 顾伯勤

    2001-01-01

    The concept o the reliability of gasketsealing sytems is put fotqard.According to the reaction model and interference principle,the r frmula calculating the reliability og gasker selling systems is derived and the reliabilityisanalyzed with theanalytic method and the monte catloethod.furthermore,the design method of gasket sealing systems based on the prescribdd reliability is also discussed in the paper.%提出了垫片密封系统可靠性的基本概念,从反应论模型出发,依据干涉模型的基本原理,导得了系统可靠度的计算公式,采用解析法和Monte Carlo法进行可靠性分析,探讨了根据所要求的可靠度进行垫片密封设计的方法。