WorldWideScience

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

    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.

  11. 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

  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. 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...

  6. 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.

  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

    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

    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.

  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. 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

  13. 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 $SG_{2,b}$.

  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. 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...

  13. 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.

  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. 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...

  8. 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.

  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. 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。

  14. 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.

  15. 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

  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. 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].

  10. 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.

  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. 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...

  1. 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...

  2. 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.

  3. 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

  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

    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

  9. 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.

  10. 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.

  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. 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...

  4. 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

  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. 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

  10. 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.

  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. 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。

  9. 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。

  10. 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.

  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. 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.

  15. 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.

  16. 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.

  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. 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.

  2. 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.

  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. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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

  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. 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...

  17. 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...

  18. 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.

  19. 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.

  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. 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.

  3. 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.

  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. 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.

  8. 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。

  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. 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.

  4. 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.

  5. 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

  6. 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.

  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。

  11. Semicarbazide is a minor thermal decomposition product of azodicarbonamide used in the gaskets of certain food jars.

    Stadler, Richard H; Mottier, Pascal; Guy, Philippe; Gremaud, Eric; Varga, Natalia; Lalljie, Sam; Whitaker, Richard; Kintscher, Jurgen; Dudler, Vincent; Read, Wendy A; Castle, Laurence

    2004-03-01

    Evidence is presented for the first time showing that semicarbazide (SEM) is a minor thermal decomposition product of the blowing agent azodicarbonamide (ADC). A novel direct analytical method based on liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESIMS/MS) has been developed to determine SEM in foamed polyvinyl chloride (PVC) seals of metal lids, as well as in commercially available ADC. The direct LC-MS/MS method for gaskets entails extraction of the gaskets in hot water, addition of ((15)N(2)(13)C)-SEM as internal standard, and injection of an aliquot directly into the LC-MS system, achieving good sensitivity (S/N = 348 for 2 ng injected on-column) and monitoring three characteristic mass transitions (m/z 76-->31; 76 -->44; 76-->59). Semicarbazide can be detected in thermally treated ADC, reaching up to 0.93 mmol mol(-1) at 220 degrees C, as determined by the direct LC-MS/MS method. This new method is also compared to the classical derivatization method using 2-nitrobenzaldehyde (2-NBA) that is routinely employed to determine SEM as an indicator of the usage of the antimicrobial drug nitrofurazone, the use of which is not authorized in the European Union (EU). Both methods revealed proportional results, with approx. 3-fold higher levels recorded by the direct SEM approach, probably due to differences in the extraction procedures used. A limited survey of plastic seals from used press twist and twist-off metal lids on food jars (non-foamed and foamed) revealed levels of SEM ranging from 2 to 8689 microg kg(-1)(average = 1593 microg kg(-1), n= 57 determinations). PMID:14978533

  12. TN trademark FLEX: a new generation of fluorocarbon o-rings developed by COGEMA logistics with enhanced characteristics at low temperature (-40 C)

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

    2004-07-01

    Three main types of elastomers are used for the sealing of radioactive material transport casks with elastomeric gaskets: EPDM, fluorocarbons type Viton {sup registered} (standard designation: FKM) and silicon rubbers. Each rubber has specific characteristics in terms of temperature range, permeability, coefficient of expansion.. For the casks where high temperatures can be reached (200 C in continuous using), FKM gaskets are generally used. The problem is that this type of gasket does not guarantee the leaktightness at -40 C, which is a regulatory requirement. Two solutions are generally used: to specify a minimum heat load or a minimum ambient temperature. The direct consequence is that it is impossible to get B(U) approvals on the new concepts when FKM gaskets are used but only B(M) approvals, which generate significant additional justification costs (multiple submittals of Safety Analysis Reports, calculation of the minimum heat load or of the minimum ambient temperature..). Thus, it is important to develop gaskets with the same performance as FKM gaskets at high temperature but with enhanced performance at low temperature (and mainly, which guarantee the leaktightness at -40 C). COGEMA LOGISTICS has qualified a new generation of fluorocarbon O-rings (TN trademark FLEX gaskets) which can be used in continuous service on a -47 C/+200 C temperature range. TN trademark FLEX gaskets will be implemented on new casks designs.

  13. TN trademark FLEX: a new generation of fluorocarbon o-rings developed by COGEMA logistics with enhanced characteristics at low temperature (-40 C)

    Three main types of elastomers are used for the sealing of radioactive material transport casks with elastomeric gaskets: EPDM, fluorocarbons type Viton registered (standard designation: FKM) and silicon rubbers. Each rubber has specific characteristics in terms of temperature range, permeability, coefficient of expansion.. For the casks where high temperatures can be reached (200 C in continuous using), FKM gaskets are generally used. The problem is that this type of gasket does not guarantee the leaktightness at -40 C, which is a regulatory requirement. Two solutions are generally used: to specify a minimum heat load or a minimum ambient temperature. The direct consequence is that it is impossible to get B(U) approvals on the new concepts when FKM gaskets are used but only B(M) approvals, which generate significant additional justification costs (multiple submittals of Safety Analysis Reports, calculation of the minimum heat load or of the minimum ambient temperature..). Thus, it is important to develop gaskets with the same performance as FKM gaskets at high temperature but with enhanced performance at low temperature (and mainly, which guarantee the leaktightness at -40 C). COGEMA LOGISTICS has qualified a new generation of fluorocarbon O-rings (TN trademark FLEX gaskets) which can be used in continuous service on a -47 C/+200 C temperature range. TN trademark FLEX gaskets will be implemented on new casks designs

  14. Caracterisation de l'effet du vieillissement en milieu aqueux sur les proprietes mecaniques de composites a matrice elastomere

    Favre, Audrey

    Rubber composites are widely used in several engineering fields, such as automotive, and more recently for inflatable dams and other innovative underwater applications. These rubber materials are composed by an elastomeric matrix while the reinforcing phase is a synthetic fabric. Since these components are expected to operate several years in water environment, their durability must be guaranteed. The use of rubber materials immersed in water is not new, in fact, these materials have been studied for almost one century. However, the knowledge on reinforced rubber composites immersed several years in water is still limited. In this work, investigations on reinforced rubbers were carried out in the framework of a research project in partnership with Alstom and Hydro-Quebec. The objective of this study was to identify rubber composites that could be used under water for long periods. Various rubber composites with ethylene-propylene-diene monomer (EPDM), silicone, EPDM/silicone and polychloroprene (Neoprene) matrices reinforced with E-glass fabric were studied. Thus, these materials were exposed to an accelerated ageing at 85 °C underwater for periods varying from 14 to 365 days. For comparison purposes, they were also immersed and aged one year at room temperature (21 °C). The impact of accelerated aging was estimated through three different characterization methods. Scanning electron microscopy (SEM) was first used to assess the quality of fiber-matrix interface. Then, water absorption tests were performed to quantify the rate of water absorption during immersion. Finally the evolution of the mechanical properties was followed by the determination of Young's modulus (E) and ultimate stress (sigmau) using a dedicated traction test. This analysis allowed to point out that the quality of the fiber-matrix interface was the main factor influencing the drop of the mechanical properties and their durability. Moreover, it was noticed that this interface could be improved

  15. Elastomeric Capture Microparticles (ECmuPs) and Their use with Acoustophoresis to Perform Affinity Capture Assays

    Cushing, Kevin Wallace

    This dissertation describes the development of elastomeric capture microparticles (ECmicroPs) and their use with acoustophoresis to perform affinity capture assays. ECμPs that function as negative acoustic contrast particles were developed by crosslinking emulsion-based droplets composed of commercially available silicone precursors followed by functionalization with avidin/biotin reagents. The size distribution of the ECμPs was very broad or narrow depending on the emulsion system that was used during the synthesis process. Elastomeric particles exhibited a very broad size distribution when a bulk-emulsion process was used; however, when microfluidic systems were utilized, their size distribution became comparatively narrow. The functionalization of elastomeric particles was accomplished by the non-specific adsorption of avidin protein followed by bovine serum albumin (BSA) blocking and bio-specific adsorption of a biotinylated-capture antibody. Polydisperse ECμPs were functionalized to bind prostate specific antigen (PSA) or IgG-phycoerythrin (PE) in aqueous media (buffer, plasma, blood); whereas monodisperse ECμPs were functionalized to bind a high density lipoprotein in the aqueous media. Polydisperse ECμPs functionalized to bind PSA in a physiological buffer (PBS pH 7.4) demonstrated nanomolar detection using flow cytometry analysis; whereas ECμPs functionalized to bind IgG-PE demonstrated picomolar detection in 10% porcine plasma. ECμPs have a specific density of ~1.03 and are more compressible than their surrounding aqueous media; which allowed the ECμPs to exhibit negative acoustic contrast properties under an ultrasonic acoustic standing wave field. The negative acoustic contrast property of ECμPs was advantageously utilized in an IgG-PE assay conducted in 0.1% whole porcine blood. The ligand-bound ECμPs suspended in the diluted blood sample were flowed through an acoustofluidic device where the application of an ultrasonic acoustic standing wave

  16. Elastomeric 2D Grating and Hemispherical Optofluidic Chamber for Multifunctional Fluidic Sensing

    Xu, Zhida

    2014-01-01

    We present an optofluidic sensor based on an elastomeric two-dimensional (2D) grating integrated inside a hemispherical fluid chamber. Laser beam is diffracted before (reflection) and after (transmission) going through the grating and liquid in the dome chamber. The sensing mechanism is investigated and simulated with a finite difference time domain (FDTD) based electromagnetic (EM) method. For experiment, by analyzing the size, power and shape of the 2D diffraction patterns, we can retrieve multiple parameters of the liquid including the refractive index, pressure and opacity with high sensitivity. We demonstrate that glucose concentration can be monitored when mixed in different concentrated phosphate buffered saline (PBS) solution. The free-solution binding of bovine serum albumin (BSA) and anti-BSA IgG is detected with this optical sensor. This low-cost, multifunctional and reliable optofluidic sensor has the potential to be used as monitor of biofluid such as blood in hemodialysis.

  17. Life Prediction of Elastomeric U Seals in Hydraulic/Pneumatic Actuators Using NSWC Handbook

    Even the rough prediction of the product test time before the lifetime test of mechanical component begins would be of use in estimating cost and deciding how to keep up with the test. The reliability predictions of mechanical components are difficult because failure or degradation mechanisms are complicated, and few plausible databases are available for lifetime prediction. Therefore, this study conducted lifetime predictions of elastomeric U seals that were respectively installed in a hydraulic actuator and a pneumatic actuator using lifetime models and a field database based on failure physics and an actual test database obtained from the NSWC handbook. To validate the results, the predicted failure rates were compared with the actual lifetime test results acquired in the lab durability tests. Finally, this study discussed an engineering procedure to determine the coefficients in the failure rate models and analyzed the sensitivity of each influential parameter on the seal lifetime

  18. Printing transferable components using microstructured elastomeric surfaces with pressure modulated reversible adhesion

    Menard, Etienne; Rogers, John A.; Kim, Seok; Carlson, Andrew

    2016-08-09

    In a method of printing a transferable component, a stamp including an elastomeric post having three-dimensional relief features protruding from a surface thereof is pressed against a component on a donor substrate with a first pressure that is sufficient to mechanically deform the relief features and a region of the post between the relief features to contact the component over a first contact area. The stamp is retracted from the donor substrate such that the component is adhered to the stamp. The stamp including the component adhered thereto is pressed against a receiving substrate with a second pressure that is less than the first pressure to contact the component over a second contact area that is smaller than the first contact area. The stamp is then retracted from the receiving substrate to delaminate the component from the stamp and print the component onto the receiving substrate. Related apparatus and stamps are also discussed.

  19. Thermomechanical analysis of thin films on temperature-dependent elastomeric substrates in flexible heterogeneous electronics

    Thermomechanical analysis is presented to study the basic temperature effects on elastomeric substrate of flexible electronics. Strains of a films-on-substrate structure related with three key temperatures are given based on the interfacial continuum model. An improved strain model is given and compared with other two models. The role of the temperature-dependent effects is highlighted and adopted to design a flexible inorganic/organic heterogeneous structure subject to little thermal action. The sensitivity analysis of three key temperatures is investigated, by which proper selection of technological parameter for poly(dimethylsiloxane) fabrication may be determined to eliminate the variation of stress of the interface in circumstances with temperature varying severely. This work contributes to systemic reliability and compatibility, structural design and thermal management of flexible electronics.

  20. BRITTLE-DUCTILE TRANSITION OF PP/EPDM/ELASTOMERIC NANO-PARTICLE TERNARY BLENDS

    Yan Xiao; Wen Cao; Ke Wang; Hong Tan; Qin Zhang; Rong-ni Du; Qiang Fu

    2006-01-01

    The brittle-ductile transition is a very important phenomenon for polymer toughening. Polypropylene (PP) is often toughened by using rubbers, e.g., ethylene-propylene diene monomer (EPDM) has often been used as a modifier. In this article, the toughening of PP by using a new kind of rubber, known as elastomeric nano-particle (ENP), and the brittleductile transition of PP/EPDM/ENP was studied. Compared to PP/EPDM binary blends, the brittle-ductile transition of PP/EPDM/ENP ternary blends occurred at lower EPDM contents. SEM experiment was carried out to investigate the etched and impact-fractured surfaces. ENP alone had no effect on the impact strength of PP, however, with the same EPDM content,PP/EPDM/ENP ternary blends had smaller particle size, better dispersion and smaller interparticle distance in contrary to PP/EPDM binary blends, which promoted the brittle-ductile transition to occur earlier.

  1. Transition to an elastomeric infusion pump in home care: an evidence-based approach.

    Broadhurst, Daphne

    2012-01-01

    A fatal overdose of a chemotherapeutic agent delivered to a patient via an electronic infusion device served as a stark reminder of the risks that infusion therapy poses to patients and health care providers and as the impetus for a strategy to optimize safe and efficient delivery of home infusion therapy. The Academic Center for Evidence-Based Practice Star Model of Knowledge Transformation was used as the evidence-based framework for the implementation of a portable infusion pump that supports home infusion of high-risk medications, leading to increased patient and caregiver satisfaction. Evaluation of this implementation supports the use of an elastomeric infusion device for a high-risk therapy. PMID:22498484

  2. A highly sensitive and flexible pressure sensor with electrodes and elastomeric interlayer containing silver nanowires

    Wang, Jun; Jiu, Jinting; Nogi, Masaya; Sugahara, Tohru; Nagao, Shijo; Koga, Hirotaka; He, Peng; Suganuma, Katsuaki

    2015-02-01

    The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present study a simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires. By increasing the relative permittivity, εr, of the composite interlayer induced by compression at high nanowire concentration, it has been possible to achieve a maximum sensitivity of 5.54 kPa-1. The improvement in sensitivity did not sacrifice or undermine the other features of the sensor. Thanks to the silver nanowire electrodes, the sensor is flexible and stable after 200 cycles at a bending radius of 2 mm, and exhibits outstanding reproducibility without hysteresis under similar pressure pulses. The sensor has been readily integrated onto an adhesive bandage and has been successful in detecting human movements. In addition to measuring pressure in direct contact, non-contact pressures such as air flow can also be detected.The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present

  3. Experimental and analytical qualification of elastomeric seals in nuclear power stations

    During refueling of the pressurized water reactor type of nuclear power stations, the cavity surrounding the top of the reactor is filled with water to maintain acceptable levels of radiation while fuel is being transferred from the reactor. A generic illustration of this type of seal is shown which was a commonly used pneumatic seal. This particular seal has continued to receive some attention since I ampersand E Bulletin 84-03 was issued. While most plants addressed this issue at some time in the past, some plants continue to address concerns about other types of seals located in the plant. At the time of the I ampersand E Bulletin 84-03, other elastomeric-type seals were examined at meetings such as those held under the auspices of the Institute of Nuclear Power Operations. This paper addresses the testing performed on the seal used in refueling as well as the analytical method employed to accomplish the same purpose

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

    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. (paper)

  5. 药用合成聚异戊二烯透明垫片性能研究%Research on Performance of Medicinal Synthetic Polyisoprene Transparent Gasket

    章卫东

    2012-01-01

    To research the physical and chemical properties,the biological performance of the medicinal synthetic polyisoprene transparent gasket.The experimental results showed that the performance of the medicinal synthetic polyisoprene transparent gasket superior to the current used gasker,especially its chemical properties,biological performance is excellent,and it is developing trend.%研究了药用合成聚异戊二烯透明垫片的理化和生物性能,结果表明,其性能优于目前使用的药用合成聚异戊二烯垫片,其中化学和生物性能尤为突出,是未来药用合成聚异戊二烯垫片的发展趋势。

  6. 八角垫密封发生泄漏的原因初探%Exploration on the Reasons that Octagonal Gasket Sealing Form Produces Leakage

    徐立志; 韩杰

    2011-01-01

    八角垫密封方式是一种化工设备中常用的密封方式.本文对这种密封方式在使用中产生泄漏的一些原因进行了分析,指出了处理对策,并说明了这种密封方式在加工、制造、使用中的一些注意事项.%Using octagonal gasket is the general sealing form in chemical equipment. In this paper, the reasons that octagonal gasket sealing form produces leakage when using were analyzed, countermeasures are pointed out, and some matters needing attention of this sealing form in the processing, manufacture and use.

  7. 2 -Distance Coloring of Sierpi(n)ski Gasket Graphs%Sierpi(n)ski Gasket图的2-距离着色

    莫明忠; 潘玉美

    2012-01-01

    运用群论中置换的思想,通过置换顶点的着色法,研究Sierpi(n)ski gasket图Sn的2-距离着色,且给出了Sierpi(n)ski gasket图Sn的2-距离色数的精确值为x2d(Sn)=6,其中n≥2.%In this paper, the authors study 2 - distance coloring of Sierpinski gasket Graphs Sn by applying vertex color permutation based on the idea of permutation in group theory. Meanwhile, the authors give the exact 2 - distance chromatic number of Sierpinski gasket graphs Sn, χ2d(Sn) = 6, where n≥2.

  8. Radiation data definitions and compilation for equipment qualification data bank

    Dose definitions, physical properties, mechanical properties, electrical properties, and particle definitions are listed for insulators and dielectrics, elastomeric seals and gaskets, lubricants, adhesives, and coatings

  9. 鱼骨垫-一种承载垫片密封的革新设计%Fishbone Gasket-An Innovation of the High Sealing Performance

    赵晶玮

    2015-01-01

    垫片密封一直都是工业安全生产的关键。该文分析了传统垫片在载荷力过大或者系统工况波动下存在的不足,提出了革新性的鱼骨垫片创新设计,介绍了鱼骨垫片的结构和密封原理,通过测试数据的对比显示,鱼骨垫不仅极大地降低了密封泄漏率,而且显著提高了生产、环境和人员健康的安全保障,为极端环境下更可靠、更牢固的密封问题提供了新的解决方案。%Gasket sealing is always the key to ensure the industrial safety. This article analyzes the weaknesses of traditional gaskets under the condition of over compression or other project environment fluctuation, and illustrates the innovated design, structure and sealing princi-ple of Fishbone Gasket. With comparision of the leakage testing provided by the worldwide well-known laboratory, it is obvious that Fish-bone Gasket not only has the capability of decreasing the sealing leakage dramatically, but also enhancing the safety of manufacture, envi-ronment and personnel. It provides a new more reliable, safer solution for severe sealing environment.

  10. 柔性石墨金属波齿复合垫片研究进展%Research Progress of Flexible Graphite Corrugated Metal Gaskets

    李力驳; 张铱鈖; 李多民

    2013-01-01

    The structure characteristics,seal mechanism and performance characteristics of flexible graphite corrugated metal gaskets were introduced,including its research achievements and successful application in petrochemical plant as well as the gasket's seriation and standardization to be solved.Carrying out the study on corrugated gaskets in a variety of applications has an important value and significance for equipment protection and stable operation.%介绍了波齿复合垫片的结构特点、密封机理和性能特点.总结了对波齿复合垫片各方面的研究成果以及波齿复合垫片在石化装置中的应用,提出现在亟待解决的问题是垫片的系列化和标准化.开展波齿复合垫片在各种应用场合的研究对于保障企业设备的安全、稳定运行具有重要的价值和意义.

  11. 一种机油冷却器加强垫圈夹持器的设计%The Design of Reinforced Gasket Gripper for Engine Oil Cooler

    翁玲灵; 朱兴龙; 孙钊

    2014-01-01

    It introduces the composition and working principle of a type of oil cooler , analyzes the features and functions of the reinforced gasket .Then it presents the method that grabs automatically the reinforced gasket in the assembling process .Based on this method , it uses a vacuum pump to drive gripper .In addition , it also illus-trates the related structure of the reinforced gasket gripper and the related calculation .%介绍了一种汽车机油冷却器的组成及工作原理,分析了加强垫圈的特点和作用,提出了在自动组片过程中加强垫圈自动抓取的方法。根据提出的方法阐述了采用真空泵驱动夹持器实现抓取的工作原理,设计了加强垫圈夹持器的相关结构并进行了相关的计算分析。

  12. Development of a CAE-based procedure for the acoustic optimization of gaskets between engine structure and add-on parts; Entwicklung eines rechnergestuetzten Verfahrens zur akustischen Optimierung von Dichtungen zwischen Motorstruktur und Anbauteilen

    Pischinger, S.; Pilath, Ch. [RWTH Aachen (Germany). Lehrstuhl Verbrennungskraftmaschinen

    2005-07-01

    The current status for calculation of structure born noise flow via elastomer gaskets is not sufficient. A simulation method developed in this project which is based on MSC Nastran shows accurate results compared to measurements. The calculation results were significantly better than those which were conducted using the state-of-the-art modal calculation approach. The key for getting good simulation results is to include the frequency dependent shear modulus of the sealing material in the calculation. The optimisation of the sealing geometry regarding to it's NVH behaviour showed that no general statement concerning the best geometry is possible. The best geometry for acoustics strongly depends on the given boundaries. Depending on the utilized sealing material different physical effects like damping or insulation come into operation. The improved acoustic behaviour of the optimised geometry was verified in an experimental analysis. In order to confirm the methodology the calculation approach was transferred to a second engine structure and verified with experimental results. (orig.)

  13. Effects of Strain-Induced Crystallization on Mechanical Properties of Elastomeric Composites Containing Carbon Nanotubes and Carbon Black

    The effects of strain-induced crystallization (SIC) on the mechanical properties of elastomeric composites as functions of extension ratio (λ), multi walled carbon nanotube (CNT) content, and carbon black (CB) content are investigated. The differential scanning calorimetry (DSC) analysis shows that the degree of crystallinity increases with the increase in the CB and CNT content. As λ increases, the glass transition temperature (Tg) of the composites increases, and the latent heat of crystallization (LHc) of the composites is maximum at λ=1.5. It is found that the mechanical properties have a linear relation with LHc, depending on the CNT content. According to the TGA (thermogravimetric analysis), the weight loss of the composite matrix is 94.3% and the weight of the composites decreases with the filler content. The ratio of tensile modulus (Ecomp/ Ematrix) is higher than that of tensile strength (σcomp/ σmatrix) because of the CNT orientation inside the elastomeric composites

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

    Hossein Aghili

    2015-02-01

    Full Text Available 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.In this lab trial study, Iranian and foreign-made elastomeric ligatures were experimentally contaminated in Streptococcus mutans, Enterococcus faecalis and Candida albicans suspensions. Ligatures were then decontaminated using 0.2% CHX as the control, 0.5 mg/ml Zataria multiflora extract mouthwashes as the test and phosphate buffered saline (PBS as the negative control for one hour. Antimicrobial properties of both solutions were evaluated by comparing the mean viable bacterial cell count on both rings after decontamination, using SPSS version 15 software.The mean viable bacterial cell count on Iranian ligatures was greater than that on foreign-made ligatures before disinfection (P=0.001, however this difference for C. albicans was not statistically significant (P=0.061. Chlorhexidine mouthwash completely eliminated all tested microorganisms attached to both elastomeric rings, but Zataria extract was only capable of completely eliminating C. albicans from both ligatures. Statistically significant differences were found in viable bacterial counts on both ligatures before and after disinfection with Zataria extract (P=0.0001.Zataria multiflora extract has antimicrobial properties and can be used for disinfection of elastomeric ligatures. In vivo studies are required to evaluate the efficacy of the incorporation of this herbal extract in mouthwashes for orthodontic patients.

  15. Synthesis and characterizations of high permittivity ultraviolet cured soft elastomeric networks and composites applicable as dielectric electroactive polymer

    Goswami, Kaustav

    The objective of this thesis was preparation and characterizations of high permittivity ultraviolet (UV) cured elastomeric networks and composites applicable as dielectric electroactive polymers (DEAPs). At present, none of the commercially available elastomers such as acrylics, poly (dimethyl......-developed processes due to better control over the heterogeneity of the networks. The sequential curing approach was successfully used to incorporate conductive multiwalled carbon nanotubes (MWCNTs) in higher concentrations than usual without making the elastomers conductive. The PDMS-MWCNT composites also showed...

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

    Dilip Kumar

    2016-01-01

    Full Text Available 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 containing 125ml of bupivacaine (0.125% was connected with the epidural catheter Pain was assessed by VAS scoring system ranging from 0 to 10. Haemodynamic parameters, quality of analgesia, degree of motor block, and adverse effect encountered were recorded at two hours interval for 24 hours at the end of two hours of subarachnoid block when operation is over. RESULTS AND OBSERVATIONS None of our patients had shown any clinically significant changes in their cardiorespiratory indices in the postoperative period. All the patients at 0 hr. were having VAS score of 0 and till 22 hours enjoyed good pain relief, i.e. VAS of 3-4. Infusion is not always steady as set by the manufacturer. There is no motor blockade after 16 hours (Bromage-0. Insignificant number of patients experienced nausea or vomiting and backache. CONCLUSIONS Elastomeric balloon pumps is a reliable device to deliver LA agents steadily and safely with 0.125% bupivacaine as continuous epidural.

  17. Compilation of current literature on seals, closures, and leakage for radioactive material packagings

    This report presents an overview of the features that affect the sealing capability of radioactive material packagings currently certified by the US Nuclear Regulatory Commission. The report is based on a review of current literature on seals, closures, and leakage for radioactive material packagings. Federal regulations that relate to the sealing capability of radioactive material packagings, as well as basic equations for leakage calculations and some of the available leakage test procedures are presented. The factors which affect the sealing capability of a closure, including the properties of the sealing surfaces, the gasket material, the closure method and the contents are discussed in qualitative terms. Information on the general properties of both elastomer and metal gasket materials and some specific designs are presented. A summary of the seal material, closure method, and leakage tests for currently certified packagings with large diameter seals is provided. 18 figs., 9 tabs

  18. The use of dual material seals for packaging

    The use of dual material seals, metal and elastomeric for a transportation package, provides a viable option for packages requiring high temperature seal capability. Allowing the seal area to go to higher temperatures then allowed for all elastomeric seal reduce the necessity of providing thermal protection during a postulated accident condition fire. It also increases the options for impact limiting features that do not also mitigate the affects of accident thermal events. Typically, high temperature seals require the use of metal O-rings. Only one seal (typically identified as the containment seal) needs to survive the hypothetical accident conditions, including the high temperatures that may occur during the prescribed hypothetical thermal event. However, to expedite the assembly leakage rate testing of radioactive material packages, a dual O-ring seal arrangement is often used to allow creation of a relatively small volume test cavity between the seals. For any package that is being used on a frequent basis, the total cost of seals can be significantly reduced by using an elastomeric seal as the secondary seal. The elastomeric seal is not the containment boundary seal and does not need to survive the high temperature condition. To get the dual material O-ring seals to seat properly, a different approach has to be taken than with closure of a radioactive material package that does not use metallic O-ring(s). A metal O-ring requires an application of a seating force while the elastomeric package requires a certain percentage of deformation. This is further complicated when the seating force is developed using a multi-bolt closure. Because of the nature of multi-bolt closures, elastic interaction prevents the equal application of force. This paper develops the methods involved in properly closing and establishing containment when using dual material seals with a multi-bolt closure. These methods were demonstrated in two production casks requiring testing leak

  19. A New Generation of Sterile and Radiopaque Impression Materials?an in vitro Cytotoxicity Study

    Coppi, Chiara; Paolinelli Devincenzi, Chiara; Bortolini, Sergio; Consolo, Ugo; Tiozzo, Roberta

    2007-01-01

    Abstract Impression materials are largely used to record the geometry of dental tissue. Hence, the assessment of their possible cytotoxicity is a necessary step in the evaluation of their biocompatibility. The present study is carried out to evaluate the cytotoxicity of a new elastomeric sterile and radiopaque impression material. Human gingival fibroblasts, cultured in vitro are exposed directly to Elite I...

  20. Modification of PVC compounds with butadiene-acrylonitrile elastomers

    J. Stabik

    2006-04-01

    Full Text Available Purpose: The purpose of the paper is to present the research programme on influence of acrylonitrile-butadiene copolymers on properties of plasticized polyvinylchloride as window gaskets material.Design/methodology/approach: Short literature review concerning application of modified PVC as gasket material was presented. In experimental part two types of acrylonitrile-butadiene copolymers were used as elastomeric plasticizers. Compounds with fifteen different levels of modifiers content (up to 25% by weight were prepared and tested. Additionally three commercial compounds were tested as reference formulations. The following test were performed: Shore hardness, short-term and long-term elastic recovery, tensile strength, elongation at break and migration of plasticizers from gasket material to unplasticized PVC.Findings: Application of acrylonitrile-butadiene copolymers as PVC modifier enhanced many properties essential for window gasket materials such as long-term and short term elastic recovery, tensile strength and elongation at break. At the same time addition of these elastomers did not change migration of other plasticizers contained in gasket material. Obtained results indicated that among tested compounds best properties as gasket material exhibited plasticized PVC with 23% of acrylonitrile-butadiene copolymer Chemigum P83. Reference commercial compounds exhibited worse performance properties than compounds with this acrylonitrile-butadiene copolymer. Practical implications: Research programme allowed to elaborate plasticized PVC compounds modified with acrylonitrile-butadiene copolymer that can be industrially applied for PVC window gaskets.Originality/value: Obtained results are of scientific and practical value. Research programme allowed to investigate the influence of elastomeric modifiers on plasticized PVC properties. Research results are also of practical importance.

  1. Highly Sensitive, Flexible, and Wearable Pressure Sensor Based on a Giant Piezocapacitive Effect of Three-Dimensional Microporous Elastomeric Dielectric Layer.

    Kwon, Donguk; Lee, Tae-Ik; Shim, Jongmin; Ryu, Seunghwa; Kim, Min Seong; Kim, Seunghwan; Kim, Taek-Soo; Park, Inkyu

    2016-07-01

    We report a flexible and wearable pressure sensor based on the giant piezocapacitive effect of a three-dimensional (3-D) microporous dielectric elastomer, which is capable of highly sensitive and stable pressure sensing over a large tactile pressure range. Due to the presence of micropores within the elastomeric dielectric layer, our piezocapacitive pressure sensor is highly deformable by even very small amounts of pressure, leading to a dramatic increase in its sensitivity. Moreover, the gradual closure of micropores under compression increases the effective dielectric constant, thereby further enhancing the sensitivity of the sensor. The 3-D microporous dielectric layer with serially stacked springs of elastomer bridges can cover a much wider pressure range than those of previously reported micro-/nanostructured sensing materials. We also investigate the applicability of our sensor to wearable pressure-sensing devices as an electronic pressure-sensing skin in robotic fingers as well as a bandage-type pressure-sensing device for pulse monitoring at the human wrist. Finally, we demonstrate a pressure sensor array pad for the recognition of spatially distributed pressure information on a plane. Our sensor, with its excellent pressure-sensing performance, marks the realization of a true tactile pressure sensor presenting highly sensitive responses to the entire tactile pressure range, from ultralow-force detection to high weights generated by human activity. PMID:27286001

  2. Static characterization of a soft elastomeric capacitor for non destructive evaluation applications

    Saleem, Hussam; Laflamme, Simon; Zhang, Huanhuan; Geiger, Randall; Kessler, Michael; Rajan, Krishna

    2014-02-01

    A large and flexible strain transducer consisting of a soft elastomeric capacitor (SEC) has been proposed by the authors. Arranged in a network setup, the sensing strategy offers tremendous potential at conducting non-destructive evaluation of large-scale surfaces. In prior work, the authors have demonstrated the performance of the sensor at tracking strain history, localizing cracks, and detecting vibration signatures. In this paper, we characterize the static performance of the proposed SEC. The characterization includes sensitivity of the signal, and temperature and humidity dependences. Tests are conducted on a simply supported aluminum beam subjected to bending as well as on a free standing sensor. The performance of the SEC is compared against off-the-shelf resistance-based strain gauges with resolution of 1 μɛ. A sensitivity of 1190 pF/ɛ is obtained experimentally, in agreement with theory. Results also show the sensor linearity over the given level of strain, showing the promise of the SEC at monitoring of surface strain.

  3. Development and evaluation of elastomeric hollow fiber membranes as small diameter vascular graft substitutes

    Mercado-Pagán, Ángel E.; Kang, Yunqing; Findlay, Michael W.; Yang, Yunzhi

    2015-01-01

    Engineering of small diameter (<6 mm) vascular grafts (SDVGs) for clinical use, remains a significant challenge. Here, elastomeric polyester urethane (PEU)-based hollow fiber membranes (HFM) are presented as an SDVG candidate to target the limitations of current technologies and improve tissue engineering designs. HFMs are fabricated by a simple phase inversion method. HFM dimensions are tailored through adjustments to fabrication parameters. The walls of HFMs are highly porous. The HFMs are very elastic, with moduli ranging from 1–4 MPa, strengths from 1–5 MPa, and max strains from 300–500%. Permeability of the HFMs varies from 0.5–3.5×10−6 cm/s, while burst pressure varies from 25 to 35 psi. The suture retention forces of HFMs are in the range of 0.8 to 1.2 N. These properties match those of blood vessels. A slow degradation profile is observed for all HFMs, with 71 to 78% of the original mass remaining after 8 weeks, providing a suitable profile for potential cellular incorporation and tissue replacement. Both human endothelial cells and human mesenchymal stem cells proliferate well in the presence of HFMs up to 7 days. These results demonstrate a promising customizable PEU HFMs for small diameter vascular repair and tissue engineering applications. PMID:25686982

  4. Caterpillar locomotion-inspired valveless pneumatic micropump using a single teardrop-shaped elastomeric membrane

    So, Hongyun

    2014-01-01

    This paper presents a microfluidic pump operated by an asymmetrically deformed membrane, which was inspired by caterpillar locomotion. Almost all mechanical micropumps consist of two major components of fluid halting and fluid pushing parts, whereas the proposed caterpillar locomotion-inspired micropump has only a single, bilaterally symmetric membrane-like teardrop shape. A teardrop-shaped elastomeric membrane was asymmetrically deformed and then consecutively touched down to the bottom of the chamber in response to pneumatic pressure, thus achieving fluid pushing. Consecutive touchdown motions of the teardrop-shaped membrane mimicked the propagation of a caterpillar\\'s hump during its locomotory gait. The initial touchdown motion of the teardrop-shaped membrane at the centroid worked as a valve that blocked the inlet channel, and then, the consecutive touchdown motions pushed fluid in the chamber toward the tail of the chamber connected to the outlet channel. The propagation of the touchdown motion of the teardrop-shaped membrane was investigated using computational analysis as well as experimental studies. This caterpillar locomotion-inspired micropump composed of only a single membrane can provide new opportunities for simple integration of microfluidic systems. © the Partner Organisations 2014.

  5. Relationship Between Structure and Dynamic Mechanical Properties of a Carbon Nanofiber Reinforced Elastomeric Nanocomposite

    The tensile and dynamic mechanical properties of a nanocomposite, containing modified carbon nanofibers (MCNFs) homogenously dispersed in an elastomeric ethylene/propylene (EP) copolymer semicrystalline matrix (84.3 wt% P), have been correlated with the structure development. These properties were characterized by in situ synchrotron X-ray diffraction during stretching, dynamic mechanical analysis and X-ray analysis techniques over a wide temperature range. Upon sequential drawing, the tensile strength of the nanocomposite film was notably higher than that of the unfilled polymer even though both samples exhibited a similar amount of crystal fraction and the same degree of crystal orientation, revealing the effect of nanofiller reinforcement in the semicrystalline matrix. The mechanical spectra of the 10 wt% MCNF filled samples in both stretched and non-stretched states showed broadening of the elastic modulus at high temperatures, where the corresponding crystallinity index also decreased. It is conceivable that a significant fraction of chain orientation is induced in the vicinity of the nanofillers during stretching, and these stretched chains with reduced mobility significantly enhance the thermal mechanical properties

  6. Caterpillar locomotion-inspired valveless pneumatic micropump using a single teardrop-shaped elastomeric membrane.

    So, Hongyun; Pisano, Albert P; Seo, Young Ho

    2014-07-01

    This paper presents a microfluidic pump operated by an asymmetrically deformed membrane, which was inspired by caterpillar locomotion. Almost all mechanical micropumps consist of two major components of fluid halting and fluid pushing parts, whereas the proposed caterpillar locomotion-inspired micropump has only a single, bilaterally symmetric membrane-like teardrop shape. A teardrop-shaped elastomeric membrane was asymmetrically deformed and then consecutively touched down to the bottom of the chamber in response to pneumatic pressure, thus achieving fluid pushing. Consecutive touchdown motions of the teardrop-shaped membrane mimicked the propagation of a caterpillar's hump during its locomotory gait. The initial touchdown motion of the teardrop-shaped membrane at the centroid worked as a valve that blocked the inlet channel, and then, the consecutive touchdown motions pushed fluid in the chamber toward the tail of the chamber connected to the outlet channel. The propagation of the touchdown motion of the teardrop-shaped membrane was investigated using computational analysis as well as experimental studies. This caterpillar locomotion-inspired micropump composed of only a single membrane can provide new opportunities for simple integration of microfluidic systems. PMID:24812661

  7. Characterisation and evaluation of soft elastomeric actuators for hand assistive and rehabilitation applications.

    Yap, Hong Kai; Lim, Jeong Hoon; Nasrallah, Fatima; Cho Hong Goh, James; Yeow, Chen-Hua

    2016-05-01

    Various hand exoskeletons have been proposed for the purposes of providing assistance in activities of daily living and rehabilitation exercises. However, traditional exoskeletons are made of rigid components that impede the natural movement of joints and cause discomfort to the user. This paper evaluated a soft wearable exoskeleton using soft elastomeric actuators. The actuators could generate the desired actuation of the finger joints with a simple design. The actuators were characterised in terms of their radius of curvature and force output during actuation. Additionally, the device was evaluated on five healthy subjects in terms of its assisted finger joint range of motion. Results demonstrated that the subjects were able to perform the grasping actions with the assistance of the device and the range of motion of individual finger joints varied from subject to subject. This work evaluated the performance of a soft wearable exoskeleton and highlighted the importance of customisability of the device. It demonstrated the possibility of replacing traditional rigid exoskeletons with soft exoskeletons that are more wearable and customisable. PMID:27007297

  8. Highly Magneto-Responsive Elastomeric Films Created by a Two-Step Fabrication Process

    Marchi, Sophie

    2015-08-24

    An innovative method for the preparation of elastomeric magnetic films with increased magneto-responsivity is presented. Polymeric films containing aligned magnetic microchains throughout their thickness are formed upon the magnetophoretic transport and assembly of microparticles during polymer curing. The obtained films are subsequently magnetized at a high magnetic field of 3 T directed parallel to the orientation of the microchains. We prove that the combination of both alignment of the particles along a favorable direction during curing and the subsequent magnetization of the solid films induces an impressive increase of the films’ deflection. Specifically, the displacements reach few millimeters, up to 85 times higher than those of the nontreated films with the same particle concentration. Such a process can improve the performance of the magnetic films without increasing the amount of magnetic fillers and, thus, without compromising the mechanical properties of the resulting composites. The proposed method can be used for the fabrication of magnetic films suitable as components in systems in which large displacements at relatively low magnetic fields are required, such as sensors and drug delivery or microfluidic systems, especially where remote control of valves is requested to achieve appropriate flow and mixing of liquids.

  9. Biodegradable, elastomeric coatings with controlled anti-proliferative agent release for magnesium-based cardiovascular stents.

    Gu, Xinzhu; Mao, Zhongwei; Ye, Sang-Ho; Koo, Youngmi; Yun, Yeoheung; Tiasha, Tarannum R; Shanov, Vesselin; Wagner, William R

    2016-08-01

    Vascular stent design continues to evolve to further improve the efficacy and minimize the risks associated with these devices. Drug-eluting coatings have been widely adopted and, more recently, biodegradable stents have been the focus of extensive evaluation. In this report, biodegradable elastomeric polyurethanes were synthesized and applied as drug-eluting coatings for a relatively new class of degradable vascular stents based on Mg. The dynamic degradation behavior, hemocompatibility and drug release were investigated for poly(carbonate urethane) urea (PCUU) and poly(ester urethane) urea (PEUU) coated magnesium alloy (AZ31) stents. Poly(lactic-co-glycolic acid) (PLGA) coated and bare stents were employed as control groups. The PCUU coating effectively slowed the Mg alloy corrosion in dynamic degradation testing compared to PEUU-coated, PLGA-coated and bare Mg alloy stents. This was confirmed by electron microscopy, energy-dispersive x-ray spectroscopy and magnesium ion release experiments. PCUU-coating of AZ31 was also associated with significantly reduced platelet adhesion in acute blood contact testing. Rat vascular smooth muscle cell (rSMC) proliferation was successfully inhibited when paclitaxel was released from pre-loaded PCUU coatings. The corrosion retardation, low thrombogenicity, drug loading capacity, and high elasticity make PCUU an attractive option for drug eluting coating on biodegradable metallic cardiovascular stents. PMID:27085049

  10. Research on Manufacture and Compression Recovery Performance of High Performance Graphite Sealing Gasket%高性能纯石墨缠绕垫的研制及回弹性能研究

    张林

    2012-01-01

    The structure of LATTYgraf REFLEX graphite sealing gasket made by the French LATTY Company was analyzed , and a pure graphite wound seal gaskets with excellent performance was designed. The gasket structure and manufacturing process were studied. By performance testing,the gasket structure parameters were optimized with resilience rate as a performance optimization indexes,and a pure graphite wound seal gaskets with the excellent performance were manufactured.%在剖析法国LATTY公司的LATTYgrf REFEX石墨密封垫片的基础上,设计一种高性能纯石墨缠绕垫片.研究该垫片的结构和制造工艺,对试制出的垫片进行性能测试,并以回弹率作为性能优化指标,对垫片结构参数进行优化,获得了性能优异的纯石墨缠绕密封垫片.

  11. 聚氯乙烯瓶盖垫蒸发残渣的检测与分析%Determination and Analysis of Evaporation Residue of PVC Gaskets

    徐国敏; 吉玉碧; 刘勇; 罗恒; 谭红

    2012-01-01

    The measurement method of evaporation residue of PVC gaskets was analyzed and studied based on area measurement method and mass measurement method, and the effect of sample shape and mass on the quantity of evaporation residue was discussed. The results showed that the quantity of evaporation residue based on area measurement method is greater than that of mass measurement method, and the quantity of evaporation residue of round-shape gaskets is greater than that of sheet-shape gaskets; sample mass shows great effect on the quantity of evaporation residue based on mass measurement method, but has little effect on that of evapora- tion residue based on area measurement method.%以质量法和面积法为基准,对聚氯乙烯(PVC)瓶盖垫蒸发残渣量测定方法进行了研究和分析,探讨了样品形状和用量对PVC瓶盖垫蒸发残渣量的影响。结果表明:采用面积法测试蒸发残渣的量大于质量法测试的,且测试样品制成垫圈形式时,测试的蒸发残渣量比制成垫片形式的样品蒸发残渣量大;样品用量对基于质量法的蒸发残渣测试结果影响很大,但对基于面积法的测试结果影响不明显。

  12. 法兰用聚四氟乙烯垫片的密封性能分析%Sealing Performance Analysis of PTFE Gasket in Flange Connection

    孙璇甍

    2016-01-01

    According to the finite element theory ,the finite element model of a pipe flange connection was established ,and the stress distribution rule of PTFE sealing gasket was researched .The distributions of von Mises stress and contact stress in preloaded state and working state were studied ,and the effect of fluid pressure on the stress and its distribution was analyzed .The results show that the von Mises stress of the gasket in the working state is greater than that in the preloaded state .Fluid pressure is bigger ,the von Mises stress of the gasket is larger ,but the effective contact width is smaller .%根据有限元理论,建立了管法兰连接有限元模型,对管法兰用聚四氟乙烯密封垫片的密封性能进行了数值计算。研究了垫片在预紧状态和工作状态下的Von Mises应力和接触应力分布,分析了管道内介质压力对其应力和应力分布的影响。结果发现:垫片在工作状态下的Von Mises应力大于其在预紧状态下的;介质压力越大,垫片的Von Mises应力越大,但垫片的有效接触宽度越小。

  13. Analyzing the photonic band gaps in two-dimensional plasma photonic crystals with fractal Sierpinski gasket structure based on the Monte Carlo method

    Hai-Feng Zhang

    2016-08-01

    Full Text Available In this paper, the properties of photonic band gaps (PBGs in two types of two-dimensional plasma-dielectric photonic crystals (2D PPCs under a transverse-magnetic (TM wave are theoretically investigated by a modified plane wave expansion (PWE method where Monte Carlo method is introduced. The proposed PWE method can be used to calculate the band structures of 2D PPCs which possess arbitrary-shaped filler and any lattice. The efficiency and convergence of the present method are discussed by a numerical example. The configuration of 2D PPCs is the square lattices with fractal Sierpinski gasket structure whose constituents are homogeneous and isotropic. The type-1 PPCs is filled with the dielectric cylinders in the plasma background, while its complementary structure is called type-2 PPCs, in which plasma cylinders behave as the fillers in the dielectric background. The calculated results reveal that the enough accuracy and good convergence can be obtained, if the number of random sampling points of Monte Carlo method is large enough. The band structures of two types of PPCs with different fractal orders of Sierpinski gasket structure also are theoretically computed for a comparison. It is demonstrate that the PBGs in higher frequency region are more easily produced in the type-1 PPCs rather than in the type-2 PPCs. Sierpinski gasket structure introduced in the 2D PPCs leads to a larger cutoff frequency, enhances and induces more PBGs in high frequency region. The effects of configurational parameters of two types of PPCs on the PBGs are also investigated in detail. The results show that the PBGs of the PPCs can be easily manipulated by tuning those parameters. The present type-1 PPCs are more suitable to design the tunable compacted devices.

  14. Leakage Analysis of Metal Octagonal Ring Gasket System with ANSYS Software%基于ANSYS的金属环形八角垫片密封系统的泄漏分析

    黄有用; 陈晔; 查俊杰

    2013-01-01

      考虑金属环形八角垫片结构特点,运用ANSYS非线性分析中的接触分析功能,对金属环形八角垫密封系统进行有限元三维数值模拟,研究附加弯矩和附加轴向力对八角垫真实接触应力的影响。结果表明,附加弯矩与附加轴向力使八角垫真实接触应力沿周向分布不均匀,其中附加弯矩对真实接触应力的影响更明显。利用分析法对八角垫片进行泄漏分析,得到附加弯矩和附加轴向力对泄漏率的关系式。STATISTICA的响应面%Considering the structural property of metal octagonal ring gasket and using contact analysis function of AN-SYS nonlinear analysis,a 3-D numerical simulation was made for metal octagonal ring-joint gasket system. The effect of ex-ternal bending moment and axial force on the gasket actual contact stress was studied. The results indicate that the distribu-tion of gasket real contact stress along circumferential direction is nonuniform due to the external bending moment and axial force,and the external bending moment has more obvious influence on the gasket real contact stress. The leakage rate of oc-tagonal ring gasket was discussed by response surface analysis of STATISTICA software,and the relational expression be-tween the leakage rate and the external bending moment and axial force.

  15. 双金属自密封波齿垫片结构参数及密封性能研究%Study on Structural Parameters and Sealing Performance of Bimetal Seal Corrugated Composite Gasket

    周先军; 卫朋; 尚庆军

    2015-01-01

    The study plot was planed with four factors and three grades adopting orthogonal experimental design method.The compressibility and resilience performance of the new gaskets was investigated adop-ting finite element analysis,the sealing performance was discussed between the new gasket and flexible graphite corrugated metal gasket.The result shows that the major element that greatly affects the compres-sibility and resilience performance of the gasket are graphite and gap;the excellent scheme is A1 B1 C1 D1;compared with the flexible graphite corrugated metal gasket,the new gasket has a better sealing perform-ance.%对双金属自密封波齿垫片运用正交试验方法设计了四因素三水平的试验方案,采用有限元方法研究其压缩回弹性能,并比较相同结构参数下波齿复合垫片与双金属自密封波齿垫片的密封性能。研究结果表明:石墨覆盖层厚度是影响双金属自密封波齿垫片压缩率的显著因素,缝宽是影响其回弹率的显著因素,双金属自密封波齿垫片的优选方案为A1 B1 C1 D1;相同预紧力下双金属自密封波齿垫片可以密封较高的内压。

  16. An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

    Jung, Wooseok; Barrett, Matthew; Brooks, Carla; Rivera, Andrew; Birdsell, Dawn N.; Wagner, David M.; Zenhausern, Frederic

    2015-12-01

    We present a new elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis. The valve functions include metering to capture a designated volume of biological sample into a polymerase chain reaction (PCR) chamber, sealing to preserve the sample during PCR cycling, and transfer of the PCR-products and on-chip formamide post-processing for the analysis of DNA fragments by capillary gel electrophoresis. This new valve differs from prior art polydimethylsiloxane (PDMS) valves in that the valve is not actuated externally by air-pressure or vacuum so that it simplifies a DNA analysis system by eliminating the need for an air-pressure or vacuum source, and off-cartridge solenoid valves, control circuit boards and software. Instead, the new valve is actuated by a thermal cycling peltier assembly integrated within the hardware instrument that tightly comes in contact with a microfluidic cartridge for thermal activation during PCR, so that it spontaneously closes the valve without an additional actuator system. The valve has bumps in the designated locations so that it has a self-alignment that does not require precise alignment of a valve actuator. Moreover, the thickness of the new valve is around 600 μm with an additional bump height of 400 μm so that it is easy to handle and very feasible to fabricate by injection molding compared to other PDMS valves whose thicknesses are around 30-100 μm. The new valve provided over 95% of metering performance in filling the fixed volume of the PCR chamber, preserved over 97% of the sample volume during PCR, and showed very comparable capillary electrophoresis peak heights to the benchtop assay tube controls with very consistent transfer volume of the PCR-product and on-chip formamide. The new valve can perform a core function for integrated nucleic acid analysis by capillary electrophoresis.

  17. An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

    We present a new elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis. The valve functions include metering to capture a designated volume of biological sample into a polymerase chain reaction (PCR) chamber, sealing to preserve the sample during PCR cycling, and transfer of the PCR-products and on-chip formamide post-processing for the analysis of DNA fragments by capillary gel electrophoresis. This new valve differs from prior art polydimethylsiloxane (PDMS) valves in that the valve is not actuated externally by air-pressure or vacuum so that it simplifies a DNA analysis system by eliminating the need for an air-pressure or vacuum source, and off-cartridge solenoid valves, control circuit boards and software. Instead, the new valve is actuated by a thermal cycling peltier assembly integrated within the hardware instrument that tightly comes in contact with a microfluidic cartridge for thermal activation during PCR, so that it spontaneously closes the valve without an additional actuator system. The valve has bumps in the designated locations so that it has a self-alignment that does not require precise alignment of a valve actuator. Moreover, the thickness of the new valve is around 600 μm with an additional bump height of 400 μm so that it is easy to handle and very feasible to fabricate by injection molding compared to other PDMS valves whose thicknesses are around 30–100 μm. The new valve provided over 95% of metering performance in filling the fixed volume of the PCR chamber, preserved over 97% of the sample volume during PCR, and showed very comparable capillary electrophoresis peak heights to the benchtop assay tube controls with very consistent transfer volume of the PCR-product and on-chip formamide. The new valve can perform a core function for integrated nucleic acid analysis by capillary electrophoresis. (paper)

  18. Elastomeric matrix composites: effect of processing conditions on the physical, mechanical and viscoelastic properties

    D. Zaimova

    2012-02-01

    Full Text Available Purpose: The aim of this study is to investigate the influence of accelerator-vulcanizing agent system and the vulcanization temperature on the properties of vulcanizates based on Natural rubber/Polybutadiene rubber (NR/BR compounds. This preliminary study will allow optimizing the composition for improving the mechanical properties and understanding the damage behaviour.Design/methodology/approach: NR/BR based composites with different vulcanization temperatures and curing systems were characterized in respect of their curing characteristics (for 140ºC and 160ºC and mechanical properties. The cure characteristics of the rubber compounds were studied by using the Monsanto MDR 2000 rheometer. The mechanical properties were investigated- tensile strength, elongation at break, tensile modulus at 100% (M100 and at 300% (M300 deformation. The hardness (Shore A and molecular mass of the samples were also determined. Scanning electron microscopy was used to study the microstructure of the fracture surfaces.Findings: The processing, physical, mechanical and viscoelastic properties and chemical structure of the mixture of Natural rubber/Polybutadiene rubber (NR/BR compounds have been evaluated in detail for the compounds of D1 and D2 (140/160.Research limitations/implications: limitations/implications: Some critical point, control of the temperature during vulcanization in press, can introduce some restrictions; these measurements can play on the final vulcanizates and in the course of processing.Practical implications: In practical way, mechanical test results (tensile and shore A give very useful information about the damage behaviour of the elastomeric matrix composites.Originality/value: Natural rubber/Polybutadiene rubber (NR/BR compounds were mixed by additions of some certain elements to improve physical, mechanical and viscoelastic properties and damage behaviours of these compounds produced under certain conditions.

  19. Development and evaluation of elastomeric hollow fiber membranes as small diameter vascular graft substitutes

    Engineering of small diameter (< 6 mm) vascular grafts (SDVGs) for clinical use remains a significant challenge. Here, elastomeric polyester urethane (PEU)-based hollow fiber membranes (HFMs) are presented as an SDVG candidate to target the limitations of current technologies and improve tissue engineering designs. HFMs are fabricated by a simple phase inversion method. HFM dimensions are tailored through adjustments to fabrication parameters. The walls of HFMs are highly porous. The HFMs are very elastic, with moduli ranging from 1–4 MPa, strengths from 1–5 MPa, and max strains from 300–500%. Permeability of the HFMs varies from 0.5–3.5 × 10−6 cm/s, while burst pressure varies from 25 to 35 psi. The suture retention forces of HFMs are in the range of 0.8 to 1.2 N. These properties match those of blood vessels. A slow degradation profile is observed for all HFMs, with 71 to 78% of the original mass remaining after 8 weeks, providing a suitable profile for potential cellular incorporation and tissue replacement. Both human endothelial cells and human mesenchymal stem cells proliferate well in the presence of HFMs up to 7 days. These results demonstrate a promising customizable PEU HFMs for small diameter vascular repair and tissue engineering applications. - Highlights: • Hollow fiber membranes (HFMs) were fabricated and evaluated. • HFM properties could be tailored through adjustments to fabrication parameters. • Properties could match or exceed those of blood vessels. • HFM showed excellent compatibility in vitro. • HFMs have the potential to be used for small diameter vascular grafts

  20. On the mobility of iron particles embedded in elastomeric silicone matrix

    Rabindranath, R.; Böse, H.

    2013-02-01

    In this contribution the rheological and magnetorheological properties of different polydimethylsiloxane (PDMS) based magnetorheological elastomers (MRE) are presented and discussed. In order to investigate the mobility of the iron particles with respect to the rheological characteristics, the iron particles were silanized with vinyltrimethoxysilane to enable a reaction between the modified particle and the cross-linking agent of the silicone elastomer. In addition, the vinyl-functionalized particles were further modified by the coupling of the superficial vinyl groups with a long-chain hydride terminated PDMS, which enables a reaction pathway with the vinyl terminated PDMS. On the other hand, the iron particles were treated with surfactants such as fatty acids, calcium and aluminum soaps, respectively, prior to vulcanization in order to increase the mobility of the iron particles in the elastomeric matrix. It was found, that both, the modification with the long-chain hydride terminated PDMS as well as the treatment with surfactants lead to an increase of the storage modulus G', the loss modulus G" and the loss factor tan δ in the magnetic field. It is concluded that both modifications, the coupling with long-chain hydride terminated PDMS as well as the treatment with surfactants, provide a greater mobility of the iron particles and hence a greater friction represented by the increase of the loss factor tan δ. Consequently it is assumed that untreated iron particles are less mobile in the rubber matrix due to covalent bonding with the silicone components, most likely due to the reaction of the hydroxyl groups on the metal surface with the silane groups of the cross-linking agent.

  1. Development and evaluation of elastomeric hollow fiber membranes as small diameter vascular graft substitutes

    Mercado-Pagán, Ángel E.; Kang, Yunqing [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Findlay, Michael W. [Department of Plastic and Reconstructive Surgery, Stanford University, Stanford, CA (United States); University of Melbourne Department of Surgery, Royal Melbourne Hospital, Parkville, VIC (Australia); Yang, Yunzhi, E-mail: ypyang@stanford.edu [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Department of Materials Science and Engineering, Stanford University, Stanford, CA (United States)

    2015-04-01

    Engineering of small diameter (< 6 mm) vascular grafts (SDVGs) for clinical use remains a significant challenge. Here, elastomeric polyester urethane (PEU)-based hollow fiber membranes (HFMs) are presented as an SDVG candidate to target the limitations of current technologies and improve tissue engineering designs. HFMs are fabricated by a simple phase inversion method. HFM dimensions are tailored through adjustments to fabrication parameters. The walls of HFMs are highly porous. The HFMs are very elastic, with moduli ranging from 1–4 MPa, strengths from 1–5 MPa, and max strains from 300–500%. Permeability of the HFMs varies from 0.5–3.5 × 10{sup −6} cm/s, while burst pressure varies from 25 to 35 psi. The suture retention forces of HFMs are in the range of 0.8 to 1.2 N. These properties match those of blood vessels. A slow degradation profile is observed for all HFMs, with 71 to 78% of the original mass remaining after 8 weeks, providing a suitable profile for potential cellular incorporation and tissue replacement. Both human endothelial cells and human mesenchymal stem cells proliferate well in the presence of HFMs up to 7 days. These results demonstrate a promising customizable PEU HFMs for small diameter vascular repair and tissue engineering applications. - Highlights: • Hollow fiber membranes (HFMs) were fabricated and evaluated. • HFM properties could be tailored through adjustments to fabrication parameters. • Properties could match or exceed those of blood vessels. • HFM showed excellent compatibility in vitro. • HFMs have the potential to be used for small diameter vascular grafts.

  2. 阀用柔性石墨金属波齿复合垫片密封失效分析及改进%Failure Analysis and Improvement of Metal Skeleton of Flexible Graphite Corrugated Metal Gaskets for Valve

    刘洁; 王强

    2013-01-01

    Under given pressure (3.5MPa) conditions, metal skeleton of flexible graphite corrugated metal gaskets occurred the seal leakage in the boundary valve. The failure analysis and improvement was proposed, which solves the problem of short -term failure of the gasket sealing.%对3.5MPa边界阀法兰密封——柔性石墨金属波齿复合垫片密封的泄漏进行了密封失效分析,并提出了改进方案,解决了垫片密封短期失效问题.

  3. Synthesis, characterization, and paclitaxel release from a biodegradable, elastomeric, poly(ester urethane)urea bearing phosphorylcholine groups for reduced thrombogenicity.

    Hong, Yi; Ye, Sang-Ho; Pelinescu, Anca L; Wagner, William R

    2012-11-12

    Biodegradable polymers with high elasticity, low thrombogenicity, and drug loading capacity continue to be pursued for vascular engineering applications, including vascular grafts and stents. A biodegradable elastomeric polyurethane was designed as a candidate material for use as a drug-eluting stent coating, such that it was nonthrombogenic and could provide antiproliferative drug release to inhibit smooth muscle cell proliferation. A phosphorylcholine containing poly(ester urethane) urea (PEUU-PC) was synthesized by grafting aminated phosphorylcholine onto backbone carboxyl groups of a polyurethane (PEUU-COOH) synthesized from a soft segment blend of polycaprolactone and dimethylolpropionic acid, a hard segment of diisocyanatobutane and a putrescine chain extender. Poly(ester urethane) urea (PEUU) from a soft segment of polycaprolactone alone was employed as a control material. All of the synthesized polyurethanes showed high distensibility (>600%) and tensile strengths in the 20-35 MPa range. PEUU-PC experienced greater degradation than PEUU or PEUU-COOH in either a saline or lipase enzyme solution. PEUU-PC also exhibited markedly inhibited ovine blood platelet deposition compared with PEUU-COOH and PEUU. Paclitaxel loaded in all of the polymers during solvent casting continued to release for 5 d after a burst release in a 10% ethanol/PBS solution, which was utilized to increase the solubility of the releasate. Rat smooth muscle cell proliferation was significantly inhibited in 1 wk cell culture when releasate from the paclitaxel-loaded films was present. Based on these results, the synthesized PEUU-PC has promising functionality for use as a nonthrombogenic, drug eluting coating on metallic vascular stents and grafts. PMID:23035885

  4. 橡胶防撞垫片参数对曲线桥力学特性的影响%Influence of Parameters of Rubber Gasket on Mechanical Characteristic of Curved Bridge

    宋波; 程景霞; 王彦旭; 毕泽锋

    2016-01-01

    The calculation model was established based on a curved bridge with two‐linking ,and the influences of parameters of rubber gasket on mechanical characteristic of curved bridge were studied .The results show that application of rubber gasket make the rotation center of curved bridge transfer and the offset direction change .When rubber gasket is arranged ,the stiffness of rubber gasket should be considered to ensure that the maximum force of gasket doesn't exceed the limit value ,and the deviation of beam body is avoided .T he impact of beam body and block stop can be reduced by addition of gasket , and the curvature ductility demand coefficient of pier bottom can be reduced .The utilization rate of rubber gasket decreases obviously and the load of relative gasket increases with the increase of gap value .Under the premise of ensuring the normal service deformation requirements of temperature of curved bridge , the gap value should be reduced as far as possible . With the increase of hardness , the strength of rubber gasket increases ,the deformation ability is weakened , and the utilization rate of rubber gasket is reduced .It is suggested that the Shore hardness value of 55 is taken as the first choice of rubber gasket .%基于某两联曲线桥建立了计算模型,通过横桥向橡胶防撞垫片的设置,研究了橡胶垫片设计参数对曲线桥动力特性的影响。结果表明:橡胶垫片的加设使曲线桥旋转中心点转移,位移偏移方向改变;在设置橡胶垫片时,应考虑橡胶垫片的刚度以保证垫片作用力最大值不超过其极限值,避免梁体出现偏移;通过垫片的加设可以减弱梁体与挡块的碰撞,降低墩底曲率延性需求系数;随着间隙值的增大,橡胶垫片利用率明显下降,相对垫片的负荷增大,在保证曲线桥温度正常服役变形要求的前提下尽量减小间隙值的取值;随着硬度的增大,橡胶垫片强度增大

  5. 球面密封结构锥形垫片的系列化研究%The Study on Serialization of Conical Gasket with Orbicular Seal Structure

    骆青业; 马少华; 应媛媛

    2015-01-01

    针对航天管路系统中常用的球面密封结构,分析了其密封机理,讨论了密封面的损坏导致介质泄漏的原因。该文以管路系统中常用的37°以及60°球面密封接头为例,研制出相应的系列化锥形垫片。通过工程实践将锥形垫片成功应用于球面密封结构解决泄漏问题,说明了其工程实用价值。%The orbicular seal structure was commonly used in pipeline system of aerospace, its sealing mechanism was analyzed, and the cause of the leakage for the damaged sealing surface was discussed. Taking 37 degree and 60 degree orbicular seal joint used commonly in pipeline system as an example, a series of corresponding conical gaskets were developed. Through engineering practice that conical gasket had been successfully applied to solve the leakage problem of orbicular seal joint, it illustrated the practical value in engineering.

  6. Rationale for the use of protective gaskets made of geotextiles and permeability evaluation of impervious coatings made of geomembranes

    Kosichenko Yuriy Mikhaylovich

    2015-03-01

    Full Text Available The purpose of this paper is to design rationale for the use of protective pads of geotextiles and geomembranes permeability of PD using these pads. In order to justify the use of protective pads made of geotextile for reducing the defectiveness geomembrane soil fractions, the existing formulas to determine the thickness of the film element of impervious devices were examined. The calculations according to the formulas show that HDPE geomembrane with a minimum thickness of 1,0 mm, the protective lining of the geotextile should be applied at the average diameter fractions of soil of more than 6,5 mm, and for geomembranes HDPE - at a diameter of soil fractions of over 15,5 mm. In order to estimate the permeability of the TFG geomembrane using additional protective linings of geotextile in the scientific article the basic design schemes of such coatings with one and two layers of protective linings of geotextiles were considered. The evaluation results of water permeability of impervious surfaces with geotextile and for comparison - without geotextiles are given in a table. As it is shown by the data presented for the design scheme with a single layer of geotextile geomembrane at the base (in the presence of small holes in the geomembrane the decrease the effectiveness of an anti-covering is more than 268,0 %, and for the settlement scheme covering with two layers of geotextile there will be a very large reduction in the efficiency, which almost completely reduces the effectiveness of the coating to the value of the geomembrane permeability of a soil layer without geomembrane with the filtration flow rate of 71,75 m /day, against water permeability of the geomembrane cover - 38,52 m /day. From the foregoing, it can be concluded that the application of a coating design of well filtering gaskets made of geotextile is justified in terms of protecting the geomembrane from mechanical damage, but greatly reduces the effectiveness of impervious cover in

  7. Low-level laser therapy effects on pain perception related to the use of orthodontic elastomeric separators

    Rachel D'Aurea Furquim

    2015-06-01

    Full Text Available INTRODUCTION: Some patients refer to pre-banding orthodontic separation as a painful orthodontic procedure. Low-level laser therapy (LLLT has been reported to have local analgesic effect. OBJECTIVE: The aim of this single-blind study was to investigate the perception of pain caused by orthodontic elastomeric separators with and without a single LLLT application (6J. METHODS: The sample comprised 79 individuals aged between 13 and 34 years old at orthodontic treatment onset. Elastomeric separators were placed in first maxillary molars at mesial and distal surfaces and kept in place for three days. The volunteers scored pain intensity on a visual analogue scale (VAS after 6 and 12 hours, and after the first, second and third days. One third of patients received laser applications, whereas another third received placebo applications and the remaining ones were controls. Applications were performed in a split-mouth design. Thus, three groups (laser, placebo and control were assessed. RESULTS: No differences were found among groups considering pain perception in all periods observed. CONCLUSION: The use of a single-dose of LLLT did not cause significant reduction in orthodontic pain perception. Overall pain perception due to orthodontic separator placement varied widely and was usually mild.

  8. Effects of Strain-Induced Crystallization on Mechanical Properties of Elastomeric Composites Containing Carbon Nanotubes and Carbon Black

    Sung, Jong Hwan; Ryu, Sang Ryeoul; Lee, Dong Joo [Yeungnam University, Gyeongsan (Korea, Republic of)

    2011-09-15

    The effects of strain-induced crystallization (SIC) on the mechanical properties of elastomeric composites as functions of extension ratio ({lambda}), multi walled carbon nanotube (CNT) content, and carbon black (CB) content are investigated. The differential scanning calorimetry (DSC) analysis shows that the degree of crystallinity increases with the increase in the CB and CNT content. As {lambda} increases, the glass transition temperature (Tg) of the composites increases, and the latent heat of crystallization (LHc) of the composites is maximum at {lambda}=1.5. It is found that the mechanical properties have a linear relation with LHc, depending on the CNT content. According to the TGA (thermogravimetric analysis), the weight loss of the composite matrix is 94.3% and the weight of the composites decreases with the filler content. The ratio of tensile modulus (E{sub comp}/ E{sub matrix}) is higher than that of tensile strength ({sigma}{sub comp}/ {sigma}{sub matrix}) because of the CNT orientation inside the elastomeric composites.

  9. Experimental Study on Sealing Performance of Flexible Graphite Gaskets Reinforced by Corrugated Metal Sheet%柔性石墨波齿复合垫片密封性能试验研究

    李军

    2015-01-01

    采用试验的方法对柔性石墨波齿复合垫片的密封性能进行研究,分析垫片泄漏率与垫片压紧力和介质压力之间的关系曲线,结果表明,垫片泄漏与垫片压紧力呈负指数关系;垫片泄漏率与介质压力之间近似于正比例关系;石墨波齿复合垫片具有良好的密封性能。%The sealing performance of flexible gasket reinforced by corrugated metal sheet was studied by experiment in this paper, and the relationships between leakage rate and gasket preload and medium pressure were analyzed. The results indicated that leakage rate was negatively related to gasket preload, leakage rate was approximately proportional to medium pressure, and sealing performance of the gasket was good.

  10. The Preformance of New Camprofile Gasket Unfer Normal Temperature%常温下新型齿形组合垫片密封性能的试验研究

    孙世锋; 杜培德

    2001-01-01

    研究了齿形组合垫片的主要性质,包括垫片的密封性能和设计参数(m,y)的计算,讨论了垫片覆层的种类、尺寸以及操作条件对其密封性能的影响。研究结果表明,齿形组合垫片具有良好的使用性能,可以较广泛地代替单一齿形垫片。%This paper deals with the property of the camprofile gasket as well as the gasket's sealing performance and the design of the parameter(m. y), and discusses the effect on the sealing performance such as the sort, size of the layer and operation condition. The camprofile gasket has advantages in usage and it can replace the single gasket in many cases.

  11. 缠绕垫片匹配凹凸面法兰接头密封泄漏的讨论%Discussion of the Leakage of Made Femadle Flange joint Sealing with Winding Gasket

    关庆贺; 张光

    2014-01-01

    With the example of the leakage of a u-shape tube type heat exchanger during hydrotest ,which caused by the pinding-out of winding gasket between tubsheet and the concave side of shell lfange,this paper discusses the gasket mininum width,dimesional deviation of male-female seal face,lfange assembly and thd characteristiscs of winding gasket. The author suggest that minimum width of gasket should be comifrmed reasonably, and related standards should be amended.%以一台U形管式a型换热器在进行壳程水压试验时管板与壳体法兰凹面间缠绕垫片被压出泄漏为事例,针对选择低公称压力等级的缠绕垫片用在高设计压力的凹凸面法兰接头密封的影响因素,从垫片最小宽度、法兰凹凸密封面尺寸偏差、垫片与法兰装配以及缠绕垫片特性等方面进行了分析,提出了在设计计算法兰时应考虑垫片最小宽度的合理确定并修订完善相关标准的建议。

  12. Development of bus body rubber profiles with additives from renewable sources: Part I – Additives characterization and processing and cure properties of elastomeric compositions

    Highlights: • Bus body rubber profiles with additives from renewable sources. • Soybean oil, vulcanization activator from ethanol production and cereal loading filler. • Physical, chemical and thermal characterization of the additives. • Processing and cure properties of elastomeric compositions. • Components commonly used by the rubber industry can be replaced by these additives. - Abstract: The goal of this work was to characterize additives from renewable sources aiming replace the components that are traditionally used by the rubber industry in a formulation with terpolymer of ethylene–propylene–diene (EPDM). Soybean oil (MD600®) was used as a plasticizer. The vulcanization activator (MDECR®) was a sub-product from cellulosic ethanol production, while the loading filler (MDCO®) was obtained from cereals. Firstly, the physical, chemical and thermal properties of these additives were investigated. Thus, a standard composition used for bus body rubber profiles and compositions containing varying proportions of these additives were prepared. The acceleration system was added in a laboratory two-roll mill after the elastomeric compositions were processed in a torque rheometer. The elastomeric compositions were characterized by their cure properties, Mooney viscosities, differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD). The addition of these additives led to a decrease in the viscosity, work, energy and Mooney viscosity of each composition, thus improving its processability. The curing characteristics of elastomeric compositions were affected by the addition of MD600® and MDECR®, leading to lower vulcanization time, while the cure properties were not affected by the addition of MDCO®

  13. Case files of the University of Massachusetts Fellowship in Medical Toxicology: Lethal dose of opioids contained in an elastomeric capsule labeled as vancomycin

    Courtney, James M.; Boyer, Edward W.

    2008-01-01

    This case describes the adulteration of a vancomycin elastomeric capsule with opioids that likely arose from degradation of heroin [29–31]. Although the clinical management of patients suffering the effects of contaminated drugs may be straightforward, the public health risk associated with adulterated pharmaceuticals and drug delivery devices should mandate a brisk response from governmental regulatory agencies.

  14. Plaque retention by self-ligating vs elastomeric orthodontic brackets: quantitative comparison of oral bacteria and detection with adenosine triphosphate-driven bioluminescence.

    Pellegrini, P.; Sauerwein, R.W.; Finlayson, T.; McLeod, J.; Covell, D.A.; Maier, T.; Machida, C.A.

    2009-01-01

    INTRODUCTION: Enamel decalcification is a common problem in orthodontics. The objectives of this randomized clinical study were to enumerate and compare plaque bacteria surrounding 2 bracket types, self-ligating (SL) vs elastomeric ligating (E), and to determine whether adenosine triphosphate (ATP)-

  15. Analysis on self-tightening capacity of metal lens gasket connected by bolted flanges%螺栓法兰连接的金属透镜垫的自紧能力分析

    弓海霞; 徐折贵; 石长伟; 王肃

    2015-01-01

    分析了螺栓法兰连接的金属透镜垫在预紧状态和工作状态下的变形情况,以及透镜垫与螺栓法兰的变形协调关系,将金属透镜垫与螺栓法兰刚度引入透镜垫法兰连接的力学计算中,推导出了金属透镜垫自紧系数计算公式,结果表明金属透镜垫自紧系数与金属透镜垫及螺栓法兰刚度有关。采用 Hertz接触理论推导出了关于透镜垫密封接触环中心最大接触压力的螺栓法兰预紧载荷与工作载荷计算公式。通过接触力学实验验证了公式的正确性,为水下密封工程中较大直径透镜垫的设计提供参考依据。%Deformation conditions of metal lens gasket connected by the bolted flanges in the preloaded state and work state and the coupled deformation between the lens gasket and bolted flanges were ana‐lyzed ,stiffness of metal lens and bolted flanges was introduced into the connection mechanics calcula‐tion ,the formulae for calculating coefficients of metal lens gasket self‐tightening was deduced and the results show that the metal lens gasket self‐tightening coefficient relates to stiffness of the metal lens gasket and the bolted flanges .Pre‐tightening load and work load calculation formula for the bolted flange with the maximum contact pressure in the center of the lens gasket contact ring was deduced by using Hertz contact theory as well .The formula was validated by a contact mechanics experiment . This work could be used as reference for design of large diameter lens gasket in underwater engineer‐ing .

  16. Study on electrical insulation property of the insulating sealing gaskets for warship piping system%舰船管系绝缘密封垫片电绝缘性能研究

    李竹影; 曹文康; 刘冶; 张晓东

    2015-01-01

    The asbestos rubber fiber gaskets and epoxy gaskets were soaked in the seawater, alkaline solution( 10%NaOH ),acid solution(10%H2SO4)and heavy oil,and the variation of the volume resistivity and surface resistivity of the gaskets with soaking time were studied. The results showed that the wet resistivity of the asbestos rubber fiber gaskets reduced to 102Ω( orΩ·cm)level when being soaked in the alkaline solution and acid solution for two months and the period of validity of the insulation was inferred to four months in seawater,and however, the wet resistivity of the epoxy gaskets could remain 104~6Ω(orΩ·cm)level,and as the conclu-sion,the performance of the insulation of the epoxy gaskets is much better than that of asbestos rubber fiber gaskets.%研究了用于舰船管系异种金属绝缘的石棉橡胶纤维垫片和环氧垫片在海水、碱溶液(10%NaOH溶液)、酸溶液(10%H2SO4溶液)和重油中浸泡后,其体电阻率和面电阻率随浸泡时间的变化规律.实验结果显示,石棉橡胶纤维垫片在酸、碱溶液中浸泡两个月后,其湿态电阻降低到102欧姆(或欧姆?厘米)量级,在海水中的电绝缘有效期约为4个月,环氧垫片的湿态电阻可保持为104~6欧姆(或欧姆?厘米)量级,环氧材料组成的垫片其绝缘性能远好于石棉橡胶纤维垫片的绝缘性能.

  17. 螺栓法兰金属垫片连接结构的紧密性分析方法%Method for Tightness Analysis of Bolted Flanged Connections with Metallic Gaskets

    冯秀; 顾伯勤

    2011-01-01

    The design of the connections with metallic gaskets in the current codes is based on the gasket factors or the linear sealing stress,where the strength of elements is taken for design criterion,but the quantitative leakage and tightness are not taken into consideration. The method for the tightness analysis of bolted flanged connections with metallic gaskets was put forward based on the formula of the leakage rate, the analytical method for calculating the gasket contact stress and the load-deformation equation of connections. Analysis of examples shows that the leakage rate of connections can be reduced by increasing the gasket contact stress (I. E. Increasing bolt load) , which is not significant when the gasket contact stress is higher. The smoother surface of gaskets can be used for higher sealing of connections. Taking both the strength of elements and the maximal allowable leakage rate for design criterion,a new design method of bolted flanged connections may be developed.%现行金属垫片的设计以垫片系数或线密封比压为依据,主要针对法兰强度问题,而没有定量泄漏和紧密性的概念,因此无法从理论上说明连接是否紧密.在金属垫片变截面泄漏通道的泄漏率计算公式、接触应力分布的解析算法以及连接结构变形协调分析的基础上,建立连接系统的紧密性分析方法.实例分析表明:通过增加垫片应力(即提高螺栓载荷),可降低连接的泄漏率,但当垫片应力水平较高时,效果并不显著.对于密封性要求高的连接,可以采用表面较光滑的垫片.以最大允许泄漏率为设计准则的设计方法与以强度为设计准则的规范设计方法相结合,有可能发展成为一种新的密封连接设计方法.

  18. 柔性石墨金属波齿复合垫片的分级研究%Research on Classification of Flexible Graphite Covered Wave-Serrated Metal Gaskets

    陈元; 任建民

    2015-01-01

    Standards of flexible graphite covered wave-serrated metal gaskets were analyzed. It’s found that the gasket pretightening in the condition of same pressure levels and different nominal size fluctuated around a certain value,gasket pretightening in the condition of same nominal size and different pressure levels were not identical.The finite element simulation of flexible graphite covered wave-serrated metal gaskets was carried out by using ANSYS WORKBENCH. The compression ratio of flexible graphite corrugated metal gaskets under different structural parameters was calculated. The result shows that the gaskets can be classified by pressure through adjusting the structural parameters. Accordingly, flexible graphite covered wave-serrated metal gaskets can be classified according to pressure.%对柔性石墨金属波齿复合垫片的标准进行了剖析,发现同一压力级别不同名义尺寸的垫片,绝大部分的预紧比压在某一应力水平附近波动,同一名义尺寸不同压力级别的垫片预紧比压各不相同。利用ANSYS WORKBENCH 对柔性石墨金属波齿复合垫片进行有限元数值模拟,计算出在规定预紧比压下不同结构参数的柔性石墨金属波齿复合垫片的压缩率,结果表明在相同预紧比压作用下不同结构的垫片压缩率各不相同。即可以通过调整垫片结构参数达到调整垫片压缩回弹性能的目的。据此,可以实现柔性石墨金属波齿复合垫片生产按压力等级区分。

  19. 新型双楔角环垫结构参数显著性分析与设计%Significant analysis and design on the structure parameters of a new double wedge angle ring gasket

    陆晓峰; 徐永杰

    2014-01-01

    The flange joint with new double wedge angle ring gasket is a self-tightening seal structure.The structural parameters of the ring gasket has an important influence on the sealing and structural integrity of the joint. In this paper, the significance analy-sis was done by orthogonal test method, which referred to the influence of structure parameters of double wedge angle ring gasket on the sealing contact pressure and joint stress, and the design of the height and small end thickness of ring gasket was also studied. The results show that the significant influence sequence of ring gasket structural parameters to the key indexes is“master-slave sur-face cone angle>ring gasket height>small end thickness>small end inner diameter”, and“20/10°” is selected as the master-slave surface cone angle. Under the pre-tightening condition and operating condition with small medium pressure: With the increase of ring gasket height, the stress of ring gasket declines linearly at first and then waves up and down with small amplitudes, and “16 mm” is selected as the height at last;With the increase of small end thickness, the stress of ring gasket waves up and down first, then there will be a smooth stress variation region, and the stress will climb up again, and“4 mm” is finally selected as the small end thickness. The stress of ring gasket declines first and then rises with the increase of medium pressure, and this shift occurs in the pressure from 4 MPa to 5 MPa.%新型双楔角环垫法兰接头是一种自紧式密封结构,环垫的结构参数对接头的密封性和结构完整性有重要影响。本文采用正交试验法,对双楔角环垫结构参数影响密封接触压力和接头应力的程度进行了显著性分析,并对环垫高度和小端厚度的设计进行了深入探讨。结果表明,双楔角环垫结构参数对接头性能衡量指标显著性影响的总体排序依次为“主从面锥角度>环垫高度>小端厚度>

  20. Study on domestic material purchasing in MSR manufacture of conventional island

    Combining the real case of Dongfang Electric (Guangzhou) Heavy Machinery Co., Ltd. trying to purchase the domestic sealing gasket as needed in the MSR of the conventional island, this paper describes the trends and relevant experience about nuclear power equipment manufacturers purchasing materials in the domestic market, and provides a reference to broadening the procurement channels of the purchasing departments of nuclear equipment manufacturers. (author)

  1. Discussion on Bolt Load of Lens Gasket Seal%透镜垫密封螺栓载荷的探讨

    刘国振; 杨晓雨; 刘利云; 张建秀

    2015-01-01

    讨论了HG/T 20582—2011中透镜垫密封的螺栓载荷,并采用有限元方法对透镜垫螺栓载荷进行了分析,指出了螺栓载荷计算公式中存在的一些问题,并提出了新的计算公式,以供工程设计参考。%The bolt load of lens gasket seal in HG/T 20582—201 1 was discussed,and the bolt load was analyzed by the finite element method.Some problems on the calculated formula of the bolt load were pointed out.The new formula was presented for engineering design reference.

  2. [Diagnostics and planning of orthodontic treatment of patients with crowded teeth position with the use of elastomeric correcting splints].

    Arsenina, O I; Riakhovskiĭ, A N; Safarova, N M

    2011-01-01

    3D scanning of plaster jaw models and further processing of the received data in editing program for three dimensional models Rapid Form 2006 Basis is one of the used methods of diagnostics of patients with crowded teeth position (measurement of anthropometric parameters of jaw models, dental arches symmetry, sizes and forms of dentitions). On 3D jaw models with crowded teeth position there were planned trajectories of gradual single tooth displacement in such a way that to move them in new correct position. Prescribing determined step with which the tooth would be moved there was made a series of individual plastic jaw models corresponding to each stage of treatment by stereolithographic method. On the received models there was made a series of elastomeric correcting splints producing some pressure upon teeth and making for their displacement. PMID:21512472

  3. Controle sismique d'un batiment en acier de 1 etage par amortisseurs elastomeres et contreventements en Chevron

    Girard, Olivier

    Actuellement, le principe de dimensionnement a la capacite est fortement utilise dans le domaine du genie parasismique. De maniere simplifiee, cette methode de dimensionnement consiste a dissiper l'energie injectee a une structure lors d'une secousse sismique par la deformation inelastique d'un element structural sacrificiel. Cette methode de dimensionne-ment permet d'obtenir des structures economiques, car cette dissipation d'energie permet de reduire substantiellement les efforts qui se retrouvent a l'interieur de la structure. Or, la consequence de ce dimensionnement est la presence de degats importants a la structure qui suivent a la secousse sismique. Ces degats peuvent engendrer des couts superieurs aux couts d'erection de la structure. Bien entendu, sachant que les secousses sismiques d'importances sont des phenomenes rares, l'ingenieur est pret a accepter ce risque afin de diminuer les couts initiaux de construction. Malgre que cette methode ait permis d'obtenir des constructions economiques et securitaires, il serait interessant de developper un systeme qui permettrait d'obtenir des performances de controle des efforts sismiques comparables a un systeme dimensionne selon un principe de dimensionnement a la capacite sans les consequences negatives de ces systemes. En utilisant les principes d'isolation a la base, il a ete possible de developper un systeme de reprise des forces sismiques (SRFS). qui permet d'obtenir un controle des efforts sismiques concurrentiels tout en gardant une structure completement elastique. Ce systeme consiste u inserer un materiel elastomere entre l'assemblage de la poutre et des contreventements a l'interieur d'un cadre contrevente conventionnel. Cette insertion permet de diminuer substantiellement la rigidite laterale du batiment, ce qui a pour consequence d'augmenter la valeur de la periode fondamentale du batiment dans lequel ces cadres sont inseres. Ce phenomene est appele le saut de periode. Ce saut de periode permet de

  4. 柔性石墨密封垫片的研究现状及发展趋势%Present Research and Development Trend of Flexible Graphite Sealing Gasket

    2013-01-01

    The present research of flexible graphite sealing gasket were summarized .The preparation and performance of flexi -ble graphite,the main structure of metal-graphite composite gasket were introduced .The preparation technology mainly includes chemical oxidation method 、electrochemical method、microwave、detonation and gaseous volatilization method .The structures in-clude metal-graphite spiral wound gasket ,flexible graphite corrugated metal gasket and metal to metal contact type gasket .The re-search status of graphite sealing mechanism were also analyzed and the main leaking models were summarized .The application of graphite seal in areas such as nuclear power and development trend were also prospected .The future development direction of graphite gasket concentrates on highly purified graphite and design of new structure .The finite element analysis as auxiliary meth-ods will become one of research hot spot .%  主要介绍了柔性石墨的性能和制备工艺,制备工艺主要分为化学氧化法、电化学法、微波法、爆炸法和气相挥发法;总结了石墨与金属组成的复合垫片的主要结构形式,包括金属石墨缠绕垫片、石墨波齿复合垫片和金属与金属接触型垫片;还分析了石墨密封机理的研究现状,总结了现有的垫片泄露模型,并对石墨密封在核电等领域的应用前景和发展趋势进行了展望,指出未来石墨垫片发展的方向主要集中于石墨提纯、新密封结构开发,而有限元分析作为辅助的研究方法将成为热点课题之一。

  5. 新型双金属自密封复合垫片的研制开发%Development of New Dual-metal Self-sealed Composite Gaskets

    吴树济

    2012-01-01

    介绍了最新专利产品——双金属自密封复合垫片的基本结构和工作原理及其特性,该垫片具有与普通强制式密封垫片完全不同的压力自密封特性.实际使用表明:在使用其他垫片无法达到密封的法兰联接上使用该新型垫片会获得很好的密封效果.%The structure, working principle and features of newly-patented dual-metal self - sealed composite gasket were presented, which has self-sealing character quite different from the general ones with forced sealing. Application results prove its outstanding sealing capability when to be used for flange connection where other gasket fails.

  6. Engineered 3D bioimplants using elastomeric scaffold, self-assembling peptide hydrogel, and adipose tissue-derived progenitor cells for cardiac regeneration

    Soler-Botija, Carolina; Bagó, Juli R; Llucià-Valldeperas, Aida; Vallés-Lluch, Ana; Castells-Sala, Cristina; Martínez-Ramos, Cristina; Fernández-Muiños, Teresa; Chachques, Juan Carlos; Pradas, Manuel Monleón; Semino, Carlos E; Bayes-Genis, Antoni

    2014-01-01

    Contractile restoration of myocardial scars remains a challenge with important clinical implications. Here, a combination of porous elastomeric membrane, peptide hydrogel, and subcutaneous adipose tissue-derived progenitor cells (subATDPCs) was designed and evaluated as a bioimplant for cardiac regeneration in a mouse model of myocardial infarction. SubATDPCs were doubly transduced with lentiviral vectors to express bioluminescent-fluorescent reporters driven by constitutively active, cardiac...

  7. 压力容器用大直径法兰连接密封垫片的选用%Selection of Connecting Sealing Gaskets for Large -diameter Flanges in Pressure Vessels

    高俊峰; 吴树济

    2012-01-01

    With the larger size and higher parameter of equipment, sealing problems for flange connection have appeared more and more prominent,meanwhile solving these problems timely has also become more and more important. It is an urgent and worthy discussion about how to select gaskets properly for large -diameter flanges. According to the characteristics of large diameter flange connection,and combined widi the characteristics of various gaskets, the gasket selecting suggestion for large - diameter flange was put forward. Besides, combined with the engineering practice, application examples were introduced where the connection sealing problems for large - diameter flange have been solved by adopting the latest patent products - double metal self sealing composite gasket.%随着设备的大型化和操作参数的不断提升,法兰连接的密封问题越来越突出,适时化解已显得越来越重要.其中,正确选择大直径法兰用垫片是急需探讨的问题.根据大直径法兰连接结构的特点,结合不同垫片的特性,提出了大直径法兰垫片的选用建议,并结合工程实践,介绍了使用专利产品——双金属自密封复合垫片解决大直径法兰连接密封问题的案例.

  8. Effect of Additives on Evaporation Residue of PVC Gasket%原料助剂对PVC密封垫蒸发残渣性能的影响研究

    吉玉碧; 徐国敏; 胡智; 罗恒; 杨照; 田井速; 谭红

    2012-01-01

    研究了PVC密封垫产品中常用原料助剂对蒸发残渣卫生性能指标的影响。结果表明,原料助剂的添加时接触水性和低乙醇食品的PVC密封垫产品的蒸发残渣影响较小;添加的CaCO。填料对乙酸蒸发残渣影响明显,DINCH为增塑剂制备的PVC密封垫乙酸蒸发残渣值最低,ATBC为增塑剂制备的PVC密封垫正己烷蒸发残渣值最低。%Effect of additives on PVC gasket evaporation residue amount was investigated. The results showed that, the use of additives has less effect on PVC gasket evaporation residue when contacting water-based and low-ethanol food; it has obvious impact on acetic acid evaporation residue when using additive CaCO3. PVC gasket has the least acetic acid evaporation residue which using plasticizer DINCH, and the least hexane evaporation residue when using plasticizer ATBC.

  9. 柔性石墨波齿复合垫片力学性能的有限元模拟%Finite Element Analysis of Mechanical Property of Corrugated Flexible Graphite Metal Gaskets

    罗伟

    2012-01-01

    基于正交分析和有限元模拟的方法研究了波齿复合垫片的金属骨架厚度、金属骨架圆弧半径及波齿深度等因素对柔性石墨波齿复合垫片力学性能的影响.计算结果表明:波齿复合垫片的金属骨架厚度对垫片的性能影响最大,优化的参数设计的波齿复合垫片有较好的压缩率和回弹率.%The orthogonal analysis and finite element method were used to analyze the influence of metal skeleton thickness, circle radius of corrugated mental gaskets and corrugated metal sheet depth on the property of corrugated metal gaskets. The calculation results indicate that the greatest influence comes from metal skeleton thickness, and the corrugated mental gasket optimized in the parameter design has better compression ratio and rebound rate.

  10. RESEARCH OF AUTOMATIC MATCHING SYSTEM FOR AUTOMOBILE GEARBOX GASKET BASED ON VC++%基于VC++的汽车变速箱垫片自动选配系统的研究

    吴德刚; 赵利平

    2011-01-01

    The quality and efficiency of assembly is affected by the selection way of the gasket for gearbox. The requirements for modern production have not satisfied by the traditional method of election of gasket. A new type of automatic matching system for the gasket of vehicle gearbox is introduced in the paper. The device based on the relative measuring theory is controlled by an industrial computer, and the interface and the control work are done by the main development tool of the Visual C++ 6. 0, so the quality and efficiency of the gearbox assembly can be improved.%汽车变速箱垫片的选取方式是影响变速箱装配质量和效率的关键,传统的选垫方法已经不能满足现代化生产的要求,为此作者研制了一种新型的汽车变速箱垫片自动选配系统.该系统采用相对测量原理,由工业计算机控制,控制部分以Visual C++ 6.0为主要开发工具完成界面和控制工作,提高了变速箱装配的质量和效率.

  11. Algorithms for Harmonic Functions and Bi-harmonic Function on the level-3 Sierpinski Gasket%三分谢尔宾斯基垫片上的调和函数与双调和函数的算法

    王丽

    2014-01-01

    在这篇文章中,我们首先介绍了三分谢尔宾斯基垫片和标准拉普拉斯算子;其次,我们推导出了三分谢尔宾斯基垫片上调和函数与双调和函数的算法。图的顶点上这些函数的算法最后得出了预垫片,也就是近似三分谢尔宾斯基垫片。%In this paper,first,we introduce the level-3 Sierpinski Gasket and standard Laplacians on it;sec-ond,we describe algorithms for the exact computation of harmonic function, bi-harmonic function for the standard Laplacians on the level-3 Sierpinski Gasket ( SG3 ) .These algorithms allow for the computation of the values of these functions on the vertices of the graphs,the pre-gaskets Gm ,that is approximate SG3 .

  12. Study by three techniques of the elastic response of Al(6061) matrix composite material with a high content (40 % vol) of SIC

    The purpose of this investigation is to study the elastic behavior of a discontinuously reinforced composite material, Al(6061)-40vol%SiC, by using three different procedures; Extensometry in uniaxial testing, pendulum elastomeric, and propagation of acoustic signals in the materials. The high ceramic content of this material provides it with a high stiffness without a significant increase in density. Because of this, the material is suitable as structural component in the automotive and aerospace industry. (Author) 8 s refs

  13. Nonlinear analysis of r.c. framed buildings retrofitted with elastomeric and friction bearings under near-fault earthquakes

    Mazza, Mirko

    2015-12-01

    Reinforced concrete (r.c.) framed buildings designed in compliance with inadequate seismic classifications and code provisions present in many cases a high vulnerability and need to be retrofitted. To this end, the insertion of a base isolation system allows a considerable reduction of the seismic loads transmitted to the superstructure. However, strong near-fault ground motions, which are characterised by long-duration horizontal pulses, may amplify the inelastic response of the superstructure and induce a failure of the isolation system. The above considerations point out the importance of checking the effectiveness of different isolation systems for retrofitting a r.c. framed structure. For this purpose, a numerical investigation is carried out with reference to a six-storey r.c. framed building, which, primarily designed (as to be a fixed-base one) in compliance with the previous Italian code (DM96) for a medium-risk seismic zone, has to be retrofitted by insertion of an isolation system at the base for attaining performance levels imposed by the current Italian code (NTC08) in a high-risk seismic zone. Besides the (fixed-base) original structure, three cases of base isolation are studied: elastomeric bearings acting alone (e.g. HDLRBs); in-parallel combination of elastomeric and friction bearings (e.g. high-damping-laminated-rubber bearings, HDLRBs and steel-PTFE sliding bearings, SBs); friction bearings acting alone (e.g. friction pendulum bearings, FPBs). The nonlinear analysis of the fixed-base and base-isolated structures subjected to horizontal components of near-fault ground motions is performed for checking plastic conditions at the potential critical (end) sections of the girders and columns as well as critical conditions of the isolation systems. Unexpected high values of ductility demand are highlighted at the lower floors of all base-isolated structures, while re-centring problems of the base isolation systems under near-fault earthquakes are

  14. Al包覆层厚度对Al-NiTi复合垫片密封面压紧力影响的有限元分析%Effect of Al cover thickness on contact stress of Al-NiTi gasket using FEM

    诸士春; 陆晓峰; 巩建鸣

    2012-01-01

    周ABAQUS分析了法兰连接中不同A1包覆层厚度下Al-NiTi复合垫片密封面压紧力的分布,并与同等加载条件下的NiTi垫片、金属石墨缠绕垫片进行了对比.结果表明,相比NiTi垫片,Al包覆层降低了密封面的压紧力,随包覆层厚度增加,降低幅度增加;包覆Al层后,垫片密封面压紧力沿径向分布呈现波纹起伏,随包覆层厚度增加,波动幅度增加;Al-NiTi复合垫片内外侧附近出现密封压紧力急剧上升的突变,且随垫片厚度减少,突变值增加,这有利于提高密封效果;Al包覆层厚度为0.2 mm时,密封面压紧力数值较为理想,甚至超过NiTi垫片和金属石墨缠绕垫片.%The contact stress distributions of Al-NiTi gaskets were studied in flange joints with different aluminum cover thickness using finite element analysis ( ABAQUS) , and the conclusions were compared with that of spiral-wound gasket and NiTi gasket. The results show that gasket contact stress decreases with increasing thickness of the cover. Contact stresses fluctuate along the radial direction after gaskets are covered with aluminum sheet, and the range of fluctuation enlarges with the increasing thickness of the cover. Contact stress at the edge of Al-NiTi gasket increases sharply, and thin cover results in higher increment, which is benefit for sealing performance of the gasket. When the thickness of aluminum cover is 0. 2 mm, gasket contact stress is reasonable, e-ven beyond the stress of NiTi gasket or spiral-wound gasket.

  15. 密封垫片高温综合性能试验机的研制%The Development of Sealing Gasket Testing Machine of Elevated Temperature Combination Property

    刘麟; 顾伯勤; 孙振国; 袁惠新

    2011-01-01

    在总结分析目前国内外密封垫片综合性能评价技术的基础上,利用低压区作为密封测漏腔,克服高压区密封腔由于密封难带来试验误差大的问题,自主研制一种高温垫片综合性能试验机.介绍该试验机的设计原理和特殊功能,采用高斯误差估计方法对试验机的泄漏率测量范围和精度进行计算,并利用该试验机对不锈钢柔性石墨缠绕垫片和石棉橡胶板垫片的高温综合性能进行试验评定.试验结果表明,所研制的密封垫片高温综合性能试验机能够准确进行垫片的压缩回弹性能、蠕变性能和密封性能测试,为静密封连接的泄漏预测与控制提供可靠的试验依据.%Based on studying combination property evaluation technology of gasket,a new sealing gasket testing machine was developed. The machine uses low pressure sealing cavity to detect leakage,which has more precise than that using high pressure area. The design principle and special function of the machine were introduced. The measurement range and accuracy of leakage rate were estimated by Gauss error function. The combination properties of stainless steel-graphite spiral wound gasket and asbestos rubber gasket were tested. The experimentation indicates this tester can simulate compression resilience, creep relaxation and sealing performances of gaskets, and it can provide experimental basis for preventing leakage.

  16. Numerical Study on Waterproof Failure Mechanism of Elastic Sealing Gasket of Underwater Shield-bored Tunnel%水下盾构隧道弹性密封垫防水失效数值模拟研究

    王湛

    2015-01-01

    In the paper,numerical simulation study is made on the waterproof failure mechanism of elastic sealing gaskets by means of ABAQUS program,with the design of the waterproof system of an underwater shield-bored tunnel as example.The finite element model used in the paper is compared with the previous simplified model,and the waterproof failure mechanism of elastic sealing gaskets in the case of joint opening and that in the case of joint staggering are analyzed respectively.Conclusions drawn are as follows:1 )In the case of joint opening,the water leakage mainly occurs at the contact surface between the sealing gaskets;2)In the case of joint staggering,the water leakage at the contact surface between the sealing gaskets turns into water leakage at the contact surface between the sealing gasket and the concrete segment as the staggering displacement grows.%结合某水下盾构隧道工程的防水设计,采用大型有限元软件 ABAQUS 对弹性密封垫的防水失效机理进行数值模拟研究。将本文有限元模型与前人简化模型进行了对比分析,并对接缝张开及接缝错开情况下的密封垫防水失效机理进行了分析。研究表明,在接缝张开的情况下,渗漏主要发生在密封垫间的接触面上;接缝错开的情况下,随错缝位移的增大,渗漏将由发生在密封垫接触面上而转变为发生在密封垫与混凝土间的接触面上。

  17. Heat shrink ability of electron-beam-modified thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer and polyethylene

    Chattopadhyay, S.; Chaki, T.K.; Bhowmick, Anil K. E-mail: anilkb@rtc.iitkgp.ernet.in

    2000-11-01

    The heat shrink ability of electron-beam-irradiated thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer (EVA) and low-density polyethylene (LDPE) has been investigated in this paper. The effects of temperature, time and extent of stretching and shrinkage temperature and time have been reported. Based on the above data, the optimized conditions in terms of high heat shrinkage and low amnesia rating have been evaluated. Influence of radiation doses (0-500 kGy), multifunctional sensitizer levels (ditri methylol propane tetraacrylate, DTMPTA), and blend proportions on heat shrink ability has been explained with the help of gel fraction and X-ray data. With the increase in radiation dose, gel fraction increases, which in turn gives rise to low values of heat shrinkage and amnesia rating. At a constant radiation dose and blend ratio, percent heat shrinkage is found to decrease with increase in DTMPTA level. Gel content increases with the increase in EVA content of the blend at a constant radiation dose and monomer level, giving rise to decrease in heat shrink ability. Heat shrinkage increases with the increase in percent crystallinity, although the amnesia rating follows the reverse trend.

  18. Heat shrink ability of electron-beam-modified thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer and polyethylene

    The heat shrink ability of electron-beam-irradiated thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer (EVA) and low-density polyethylene (LDPE) has been investigated in this paper. The effects of temperature, time and extent of stretching and shrinkage temperature and time have been reported. Based on the above data, the optimized conditions in terms of high heat shrinkage and low amnesia rating have been evaluated. Influence of radiation doses (0-500 kGy), multifunctional sensitizer levels (ditri methylol propane tetraacrylate, DTMPTA), and blend proportions on heat shrink ability has been explained with the help of gel fraction and X-ray data. With the increase in radiation dose, gel fraction increases, which in turn gives rise to low values of heat shrinkage and amnesia rating. At a constant radiation dose and blend ratio, percent heat shrinkage is found to decrease with increase in DTMPTA level. Gel content increases with the increase in EVA content of the blend at a constant radiation dose and monomer level, giving rise to decrease in heat shrink ability. Heat shrinkage increases with the increase in percent crystallinity, although the amnesia rating follows the reverse trend.

  19. Development of elastomeric lab-on-a-chip devices through Proton Beam Writing (PBW) based fabrication strategies

    In recent years, one of the most exciting developments in fluidic device applications is the rapid evolution of miniaturized micro- and nanofluidic systems, the so called 'lab-on-a-chip' devices. These devices integrate laboratory functions into a single chip, and are capable of various biochemical analysis and synthesis, such as sample injection and preparation, single cell/molecule observation, bioparticle sequencing and sorting etc. The evolvement of lab-on-a-chip concept implies the use of novel fabrication techniques for the construction of versatile analytical components in a fast and reproducible manner. Endowed with unique three-dimensional fabrication abilities, Proton Beam Writing (PBW) , which is capable of producing nanometer scaled fluidic structures with smooth and straight side wall features, has a great potential to develop all sorts of polymer fluidic devices. In this paper, we describe the batch fabrication of Poly-dimethysiloxane (PDMS) elastomeric lab-on-a-chip devices utilizing PBW technique. A series of fabrication processes, involving PBW, nickel electroplating, soft lithography, polymer dynamic coating and hydrophilic treating, were modified and adopted in our work. Subsequent characterization of individual categories of channel devices was carried out for specific fluidic studies. Respective experimental procedures are presented and results are explained. The channel devices demonstrated good fluidic performance and functionality, suggesting their further application in more complex biological investigations, and the versatility of PBW in lab-on-a-chip development.

  20. Seismic vulnerability assessment of a steel-girder highway bridge equipped with different SMA wire-based smart elastomeric isolators

    Hedayati Dezfuli, Farshad; Shahria Alam, M.

    2016-07-01

    Shape memory alloy wire-based rubber bearings (SMA-RBs) possess enhanced energy dissipation capacity and self-centering property compared to conventional RBs. The performance of different types of SMA-RBs with different wire configurations has been studied in detail. However, their reliability in isolating structures has not been thoroughly investigated. The objective of this study is to analytically explore the effect of SMA-RBs on the seismic fragility of a highway bridge. Steel-reinforced elastomeric isolators are equipped with SMA wires and used to isolate the bridge. Results revealed that SMA wires with a superelastic behavior and re-centering capability can increase the reliability of the bearing and the bridge structure. It was observed that at the collapse level of damage, the bridge isolated by SMA-HDRB has the lowest fragility. Findings also showed that equipping NRB with SMA wires decreases the possibility of damage in the bridge while, replacing HDRB with SMA-HDRB; or LRB with SMA-LRB increases the failure probability of the system at slight, moderate, and extensive limit states.

  1. Study of the hydro-mechanical behaviour of expanded graphite gaskets; Etude du comportement et de l`etancheite de joints en graphite expnase

    Patron, E. [Electricite de France (EDF), Direction des Etudes et Recherches, 92 - Clamart (France)

    1997-12-31

    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). 21 refs.

  2. Statistical study of static gasket conductance; Etude statistique de la conductance d'un joint d'etancheite statique

    Flukiger, F

    2005-10-15

    This work is motivated by tightness technological problems associated with metallic gasket. The objective is a better understanding of leakage mechanisms, through the development of new computational tools. In this study, the aperture field between two rough surfaces in contact is described by a short correlated isotropic random Gaussian process. The system is studied as a set of independent elementary surfaces. Joint conductances are evaluated from a statistical study on those elementary surfaces. A computational code is developed using a network approach based on lubrication theory estimation of local conductances. The global conductance computation becomes analogous to an electrical problem for which the resistances are distributed on a random network. The network is built from the identification of the aperture field critical points. Maxima are linked through saddle points. Bond conductances are estimated at the aperture field saddle points. First, a purely plastic model of deformations is considered. Near percolation threshold the conductances display a power behaviour. Far from percolation threshold, numerical results are favourably compared with an effective medium approximation. Secondly, we study the impact of elastic deformations. A computational code based on Boussinesq approximation is coupled to the network approach. The results indicate a significant impact of elastic deformations on conductances. Finally, the network approach is adapted to simulate quasi-static drainage thanks to a classical invasion percolation algorithm. A good comparison between previous experiments and numerical predictions is obtained. (author)

  3. Elastomeric degradable biomaterials by photopolymerization-based CAD-CAM for vascular tissue engineering

    Baudis, Stefan; Nehl, Franziska; Ligon, S Clark; Liska, Robert [Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163MC, A-1060 Vienna (Austria); Nigisch, Anneliese; Bernhard, David [Department of Surgery, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Bergmeister, Helga [Core Unit for Biomedical Research, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Stampfl, Juergen, E-mail: robert.liska@tuwien.ac.at [Institute of Material Science and Technology, Vienna University of Technology, Favoritenstrasse 9-11, A-1040 Vienna (Austria)

    2011-10-15

    A predominant portion of mortalities in industrial countries can be attributed to diseases of the cardiovascular system. In the last decades great efforts have been undertaken to develop materials for artificial vascular constructs. However, bio-inert materials like ePTFE or PET fail as material for narrow blood vessel replacements (coronary bypasses). Therefore, we aim to design new biocompatible materials to overcome this. In this paper we investigate the use of photoelastomers for artificial vascular constructs since they may be precisely structured by means of additive manufacturing technologies. Hence, 3D computer aided design and manufacturing technologies (CAD-CAM) offer the possibility of creating cellular structures within the grafts that might favour ingrowth of tissue. Different monomer formulations were screened concerning their suitability for this application but all had drawbacks, especially concerning the suture tear resistance. Therefore, we chose to modify the original network architecture by including dithiol chain transfer agents which effectively co-react with the acrylates and reduce crosslink density. A commercial urethane diacrylate was chosen as base monomer. In combination with reactive diluents and dithiols, the properties of the photopolymers could be tailored and degradability could be introduced. The optimized photoelastomers were in good mechanical accordance with native blood vessels, showed good biocompatibility in in vitro tests, degraded similar to poly(lactic acid) and were successfully manufactured with the 3D CAD-CAM technology.

  4. Elastomeric degradable biomaterials by photopolymerization-based CAD-CAM for vascular tissue engineering

    A predominant portion of mortalities in industrial countries can be attributed to diseases of the cardiovascular system. In the last decades great efforts have been undertaken to develop materials for artificial vascular constructs. However, bio-inert materials like ePTFE or PET fail as material for narrow blood vessel replacements (coronary bypasses). Therefore, we aim to design new biocompatible materials to overcome this. In this paper we investigate the use of photoelastomers for artificial vascular constructs since they may be precisely structured by means of additive manufacturing technologies. Hence, 3D computer aided design and manufacturing technologies (CAD-CAM) offer the possibility of creating cellular structures within the grafts that might favour ingrowth of tissue. Different monomer formulations were screened concerning their suitability for this application but all had drawbacks, especially concerning the suture tear resistance. Therefore, we chose to modify the original network architecture by including dithiol chain transfer agents which effectively co-react with the acrylates and reduce crosslink density. A commercial urethane diacrylate was chosen as base monomer. In combination with reactive diluents and dithiols, the properties of the photopolymers could be tailored and degradability could be introduced. The optimized photoelastomers were in good mechanical accordance with native blood vessels, showed good biocompatibility in in vitro tests, degraded similar to poly(lactic acid) and were successfully manufactured with the 3D CAD-CAM technology.

  5. A Study on Shielding Effectiveness of Conductive Gasket Material%导电衬垫材料的屏蔽效能研究

    沈菊军; 史建东

    2006-01-01

    导电衬垫是当损耗由接缝与结合面产生时,用以恢复屏蔽完整性的极重要的屏蔽材料.文中结合屏蔽机柜设计中的需要,对备选的几种衬垫材料的屏蔽性能进行了测试,得出了一些具有工程应用价值的数据和结论.

  6. 席尔宾斯基垫片在格网DEM信息伪装中的应用%Study of Sierpinski Gasket used in grid DEM information disguise

    陈令羽; 宋国民; 李黎亮

    2013-01-01

    DEM具有十分重要的军事经济价值,格网DEM是其最常见的一种表现方式.本文通过探讨席尔宾斯基垫片的一些性质,结合数字高程模型的数据特点,给出了席尔宾斯基垫片应用于DEM数据信息伪装的方法并进行了安全性分析,实现了n维席尔宾斯基垫片情况下的DEM信息伪装.通过实验分析了伪装效果与各种影响要素之间的关系.所提出的DEM伪装算法迷惑性强、安全性能良好,可以为DEM数据的存储和传输提供有力的技术保障.%DEM has very important military and economy value, grid DEM is the usually represented way. This paper discussed the character of Sierpinski Gasket, according to the characteristics of digital elevation model ( DEM) , studied the method of Sierpinski Gasket used in DEM information disguise, and analyzed its safety, carried out the disguises process under n dimension Sierpinski Gasket Then, this paper validated the feasibility through experiments, and found the relation between the impression and some factors. The arithmetic for DEM information disguise has characteristics as strong captivation and good safety, could provide a forceful technique guarantee for DEM's saving and delivering.

  7. Printing Three-Dimensional Heterogeneities in the Elastic Modulus of an Elastomeric Matrix.

    Abdel Fattah, Abdel Rahman; Ghosh, Suvojit; Puri, Ishwar K

    2016-05-01

    We present a rapid and controllable method to create microscale heterogeneities in the 3D stiffness of a soft material by printing patterns with a ferrofluid ink. An ink droplet moved through a liquid polydimethylsiloxane (PDMS) volume using an externally applied magnetic field sheds clusters of magnetic nanoparticles (MNPs) in its wake. By varying the field spatiotemporally, a well-defined three-dimensional curvilinear feature is printed that contains MNP clusters. Subsequent cross-linking of the PDMS preserves the feature in place after the magnetic field is removed. Since the ferrofluid ink interferes with the cross-linking of PDMS, a 3D print containing ink density variations leads to corresponding spatial deviations in the elastic modulus of the matrix. The modulus is mapped in the experiments with atomic force microscopy. This rapid method to print 3D heterogeneities in soft matter promises the ability to mimic mechanical variations that occur in natural biomaterials. PMID:27088326

  8. Buckling Instability of Dielectric Elastomeric Plates for Soft, Bio-Compatible Microfluidic Pumps

    Tavakol, Behrouz; Bozlar, Michael; Froehlicher, Guillaume; Punckt, Christian; Stone, Howard A.; Aksay, Ilhan; Holmes, Douglas

    2013-03-01

    Dielectric elastomers are well-known for their superior stretchability and permittivity. A fully-clamped thin elastomer will buckle when it is compressed by applying sufficient electric potentials to its sides. When embedded within soft, silicone rubbers, these advanced materials can provide a means for a bio-compatible pumping mechanism that can be used to inject bio-fluids with desired flow rates into microfluidic devices, tissues, and organs of interest. We have incorporated a dielectric film that is sandwiched between two thin, flexible, solid electrodes into a microfluidic device and utilized a voltage-induced out-of-plane buckling instability for pumping of fluids. We experimentally quantify the voltage-induced plate buckling and measure the fluid flow rate when the structure is embedded in a microchannel. Additionally, we offer an analytical prediction that uses plate buckling theory to estimate the flow rate as a function of applied voltage.

  9. Finite Element Analysis of Sealing Performance of T Profile Cylinder Head Cover Gasket%T形气缸盖罩垫密封性能的有限元分析

    丘佛球; 章争荣; 吴克胜; 何洪; 陈奕沁

    2015-01-01

    The distributions of the stress,strain and contact stress of the flat type,stiffener type and boss type T profile cylinder head cover gasket were analyzed by using the finite element software.The sealing capability of these types of T profile cylinder head cover gasket was compared.The results show that the sealing capability can be improved by the stiff-eners,but different structure types of stiffeners have different effects on the sealing capability,unreasonable designed stiff-eners will easily cause the fast failure and aging of T profile cylinder head cover gasket.The flat type gasket is applicable to the condition of long sealing time but not too high sealing stress;while the stiffener type is applicable to the condition of high sealing stress but short sealing time.The boss type has high synthetic performance,which can be applicable to the condition of high sealing stress and long sealing time.%运用有限元软件对平型、加强筋型和凸台型 T 形缸垫的应力、应变以及接触应力分布规律进行研究,对比分析这几种 T 形缸垫的密封性能。结果表明,加强筋能提高缸垫的密封能力,但不同的加强筋结构对密封能力有着不同的影响,设计不合理的加强筋,还容易导致 T 形气缸盖罩垫过快失效和老化。平型气缸盖罩垫适用于密封周期长但密封力要求不高的情况;而加强筋型气缸盖罩垫则适用于密封力要求高但密封周长不长的情况;凸台型气缸盖罩垫的综合性能高,能满足密封周期长和密封力要求比较高的情况。

  10. Fabrication and characterization of elastomeric polyester/carbon nanotubes nanocomposites for biomedical application.

    Meng, Z X; Zheng, W; Ding, M H; Zhou, H M; Chen, X Q; Chen, J C; Liu, M K; Zheng, Y F

    2011-04-01

    A novel biodegradable polymer elastomer nanocomposite composing of poly(1,8-octanediol-citrate) (POC) polymer matrix and carbon nanotubes (CNTs) additive was successfully fabricated and systematically investigated using Fourier transform infrared (FT-IR), X-ray diffractometer (XRD), differential scanning calorimetry (DSC), tensile test, incubation and cytotoxicity tests. It was found that the addition of CNTs in POC elastomer did not result in any noticeable change in its chemical structure and the amorphous state. However, the tensile strength and elongation at break were greatly improved by the addition of CNTs in POC polymer matrix. It revealed that the swelling ratio and percentage of weight loss of POC/CNTs nanocomposite were lower, compared with the pure POC material. Moreover, the adsorption amount of bovine serum albumin (BSA) increased with an increase of the CNTs mass content in POC matrix revealing the enhanced hydrophilicity of POC/CNTs nanocomposites contributed by the carboxyl of the CNTs. Additionally, the cytotoxicity tests with L929 cell line revealed that the experimental POC/CNTs nanocomposites possessed good in vitro biocompatibility. PMID:21776679

  11. Bio-inspired structural bistability employing elastomeric origami for morphing applications

    A structural concept based upon the principles of adaptive morphing cells is presented whereby controlled bistability from a flat configuration into a textured arrangement is shown. The material consists of multiple cells made from silicone rubber with locally reinforced regions based upon kirigami principles. On pneumatic actuation these cells fold or unfold based on the fold lines created by the interaction of the geometry with the reinforced regions. Each cell is able to maintain its shape in either a retracted or deployed state, without the aid of mechanisms or sustained actuation, due to the existence of structural bistability. Mathematical quantification of the surface texture is introduced, based on out-of-plane deviations of a deployed structure compared to a reference plane. Additionally, finite element analysis is employed to characterize the geometry and stability of an individual cell during actuation and retraction. This investigation highlights the critical role that angular rotation, at the center of each cell, plays on the deployment angle as it transitions through the elastically deployed configuration. The analysis of this novel concept is presented and a pneumatically actuated proof-of-concept demonstrator is fabricated. (paper)

  12. Mechanically tunable aspheric lenses via additive manufacture of hanging elastomeric droplets for microscopic applications

    Fuh, Yiin-Kuen; Chen, Pin-Wen; Lai, Zheng-Hong

    2016-07-01

    Mechanically deformable lenses with dynamically tunable focal lengths have been developed in this work. The fabricated five types of aspheric polydimethylsiloxane (PDMS) lenses presented here have an initial focal length of 7.0, 7.8, 9.0, 10.0 and 10.2 mm. Incorporating two modes of operation in biconvex and concave-convex configurations, the focal lengths can be tuned dynamically as 5.2-10.2, 5.5-9.9, 6.6-11.9, 6.1-13.5 and 6.6-13.5 mm respectively. Additive manufacturing was utilized to fabricate these five types of aspheric lenses (APLs) via sequential layering of PDMS materials. Complex structures with three-dimensional features and shorter focal lengths can be successfully produced by repeatedly depositing, inverting and curing controlled PDMS volume onto previously cured PDMS droplets. From our experiments, we empirically found a direct dependence of the focal length of the lenses with the amount (volume) of deposited PDMS droplets. This new mouldless, low-cost, and flexible lens fabrication method is able to transform an ordinary commercial smartphone camera into a low-cost portable microscope. A few microscopic features can be readily visualized, such as wrinkles of ladybird pupa and printed circuit board. The fabrication technique by successively applying hanging droplet and facile mechanical focal-length-tuning set-up can be easily adopted in the development of high-performance optical lenses.

  13. Elastomeric Polymers for Retrofitting of Reinforced Concrete Structures against the Explosive Effects of Blast

    S. N. Raman

    2012-01-01

    Full Text Available The main distinction of blast load from other types of dynamic loadings is its impulsive nature, where the loads usually act for a very short duration but transmit very high impulsive pressures. This paper presents an overview of the present retrofitting techniques in use to enhance the capacity of structural elements to withstand the effects of blast loads, and introduces an alternative retrofitting approach by utilizing polymer coatings. The authors have demonstrated the positive effects of this approach by conducting a numerical investigation on the behavior of an unretrofitted reinforced concrete panel subjected to the blast load from a 2 kg charge at 1.6 m stand-off distance, and subsequently comparing its performance with several polymer coated panels. The analysis was performed by using an explicit nonlinear finite element (FE code. The results demonstrate the contributions of this technique in terms of panel displacement control and energy dissipation. Considering that the polymer coating can also act as a protective layer in improving the durability of structural materials, this technique can also be optimized favorably to enhance the overall sustainability of structures.

  14. Integrated elastomeric components for autonomous regulation of sequential and oscillatory flow switching in microfluidic devices

    Mosadegh, Bobak; Kuo, Chuan-Hsien; Tung, Yi-Chung; Torisawa, Yu-Suke; Bersano-Begey, Tommaso; Tavana, Hossein; Takayama, Shuichi

    2010-06-01

    A critical need for enhancing the usability and capabilities of microfluidic technologies is the development of standardized, scalable and versatile control systems. Electronically controlled valves and pumps typically used for dynamic flow regulation, although useful, can limit convenience, scalability and robustness. This shortcoming has motivated the development of device-embedded non-electrical flow-control systems. Existing approaches to regulate operation timing on-chip, however, still require external signals such as timed generation of fluid flow, bubbles, liquid plugs or droplets or an alteration of chemical compositions or temperature. Here, we describe a strategy to provide device-embedded flow switching and clocking functions. Physical gaps and cavities interconnected by holes are fabricated into a three-layer elastomer structure to form networks of fluidic gates that can spontaneously generate cascading and oscillatory flow output using only a constant flow of Newtonian fluids as the device input. The resulting microfluidic substrate architecture is simple, scalable and should be applicable to various materials. This flow-powered fluidic gating scheme brings the autonomous signal processing ability of microelectronic circuits to microfluidics where there is the added diversity in current information of having distinct chemical or particulate species and richness in current operation of having chemical reactions and physical interactions.

  15. High friction on ice provided by elastomeric fiber composites with textured surfaces

    Rizvi, R.; Naguib, H.; Fernie, G.; Dutta, T.

    2015-03-01

    Two main applications requiring high friction on ice are automobile tires and footwear. The main motivation behind the use of soft rubbers in these applications is the relatively high friction force generated between a smooth rubber contacting smooth ice. Unfortunately, the friction force between rubber and ice is very low at temperatures near the melting point of ice and as a result we still experience automobile accidents and pedestrian slips and falls in the winter. Here, we report on a class of compliant fiber-composite materials with textured surfaces that provide outstanding coefficients of friction on wet ice. The fibrous composites consist of a hard glass-fiber phase reinforcing a compliant thermoplastic polyurethane matrix. The glass-fiber phase is textured such that it is aligned transversally and protruding out of the elastomer surface. Our analysis indicates that the exposed fiber phase exhibits a "micro-cleat" effect, allowing for it to fracture the ice and increase the interfacial contact area thereby requiring a high force to shear the interface.

  16. Synthesis and characterization of conductive, biodegradable, elastomeric polyurethanes for biomedical applications.

    Xu, Cancan; Yepez, Gerardo; Wei, Zi; Liu, Fuqiang; Bugarin, Alejandro; Hong, Yi

    2016-09-01

    Biodegradable conductive polymers are currently of significant interest in tissue repair and regeneration, drug delivery, and bioelectronics. However, biodegradable materials exhibiting both conductive and elastic properties have rarely been reported to date. To that end, an electrically conductive polyurethane (CPU) was synthesized from polycaprolactone diol, hexadiisocyanate, and aniline trimer and subsequently doped with (1S)-(+)-10-camphorsulfonic acid (CSA). All CPU films showed good elasticity within a 30% strain range. The electrical conductivity of the CPU films, as enhanced with increasing amounts of CSA, ranged from 2.7 ± 0.9 × 10(-10) to 4.4 ± 0.6 × 10(-7) S/cm in a dry state and 4.2 ± 0.5 × 10(-8) to 7.3 ± 1.5 × 10(-5) S/cm in a wet state. The redox peaks of a CPU1.5 film (molar ratio CSA:aniline trimer = 1.5:1) in the cyclic voltammogram confirmed the desired good electroactivity. The doped CPU film exhibited good electrical stability (87% of initial conductivity after 150 hours charge) as measured in a cell culture medium. The degradation rates of CPU films increased with increasing CSA content in both phosphate-buffered solution (PBS) and lipase/PBS solutions. After 7 days of enzymatic degradation, the conductivity of all CSA-doped CPU films had decreased to that of the undoped CPU film. Mouse 3T3 fibroblasts proliferated and spread on all CPU films. This developed biodegradable CPU with good elasticity, electrical stability, and biocompatibility may find potential applications in tissue engineering, smart drug release, and electronics. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2305-2314, 2016. PMID:27124702

  17. Compression and shear properties of elastomeric bearing using finite element analysis

    2Faculty of Science and Technology, Chiang Mai Rajabhat University, Muang, Chiang Mai, 50300 Thailand.

    2006-09-01

    Full Text Available Standard size samples of four natural rubber compounds, varying the amount of carbon black from 10 to 70 phr, were characterised under uniaxial compression and simple shear tests in order to obtain the strain energy function constants. These constants were then used as hyperelastic material constants for the Windows-based finite element package (COSMOS/M version 1.75. The investigated bearings, made with those NR compounds, had the approximate area and thickness of 50x106 mm2 and 50 mm respectively. Each compound of bearing consisted of four different values of shape factor ranging from about 0.33 to 1.70, according to the number of reinforcing plates in the bearing. Three deformation modes of compression, shear and compression-shear were predicted. Good agreement was found between twelve compression model predictions and the corresponding experimental values of bearings, containing 10, 20 and 40 phr of carbon black and each of which consisted of four different layers of reinforcing metal plates (0, 1, 2 and 3 layers. On the other hand, deviation from the predicted valve was clearly seen in the 70 phr black bearing case. The percentage difference increased with respect to the increasing number of reinforcing plates or the rising shape factor. Therefore, the improved FEA model was supplemented with an imaginary elastic glue layer between the rubber block and metal plate as glue failure compensation. The optimum value of the elastic layers modulus is 8 MPa while the thickness of the layer depends on the total thickness or total volume of rubber block. This model can predict the 70 phr carbon black bearings, having shape factor ranging from 0.5 to 2.35 for 11 cases. The FEA prediction of shear behaviour agrees well with the experimental data for all four bearing compounds and there is no effect of shape factor on shear stress. Moreover, shear stress does not depend on the compressive force applied to like bearing before shear and the FEA results

  18. Optimization of the heavy metal (Bi-W-Gd-Sb) concentrations in the elastomeric shields for computer tomography (CT)

    Eight elastomeric composites (NRU, GR1-GR4, NRBG08-NRBG24) containing mixtures of different proportions of heavy metal additives (Bi, W, Gd and Sb) have been synthesized and examined as protective shields. The NRU sample was a pure rubber matrix and served as a reference sample for heavy metal modified composites. Experimental procedure used for evaluation of the composite shields and their attenuation properties was based on the utilization of HPGe spectrometry and analysis of X-ray fluorescence radiation intensity of the heavy metal additives in the following energy ranges for: Sb (20-35 keV), Gd (35-55 keV), W (55-70 keV) and Bi (70-90 keV). The main contributor to the induced X-ray fluorescence radiation within the shield is Bi additive and the intensity of the X-ray radiation generated within the energy range of 70-90 keV strongly depends on its concentration. It was found that decreasing concentration of the Bi fraction from 0.35 (GR samples) to 0.15 (NRBG samples) results in significant lowering Bi X-ray fluorescence radiation within the 70-90 keV energy range. Secondary effect of decreasing Bi concentration was efficient diminishing excitation processes for lower Z heavy metal additives (W, Gd and Sb, GR vs. NRBG samples). As the final quality parameter of the shielding properties for the examined elastomers, dose reduction factor (DRF) coefficients were calculated for each shield. It was found, that the best shielding properties are observed for composites with lower Bi concentration (0.15 vs. 0.35 Bi mass fraction) with only slight further improvement of their parameters (DRF) with increasing of Gd concentration (Gd mass fraction 0.08, 0.16 and 0.24). The most efficient dose reduction composite was found to be NRBG24 elastomer with DRF value 0.47 (53 % dose reduction) for ca. 2 mm and 0.44 g/cm2 layer thickness. (author)

  19. Plate heat exchanger

    In a plate heat exchanger required to handle corrosive, toxic or radioactive fluids, wherein each plate has a peripheral recess or like formation adapted for receiving an elastomeric gasket, the plates are welded together in pairs by the method comprising the steps of inserting into the gasket recess of a first plate of said pair a metal packing piece and welding the second place (e.g. by a laser or electron beam weld running along the base of the recess) superimposing a second plate on to the first in contact with the packing piece and welding the second plate to the packing piece (e.g. by a laser or electron beam weld). The packing piece may be of hollow or solid cross section and is preferably of the same material (e.g. titanium or stainless steel) as the plates. In use a service fluid in heat exchange with the said corrosive etc. fluid is confined by peripheral and normally elastomeric gaskets. (author)

  20. Electrical insulating materials - Determination of the effects of ionizing radiation - Part 5: Procedures for assessment of ageing in service

    International Electrotechnical Commission. Geneva

    2003-01-01

    Covers ageing assessment methods which can be applied to components based on polymeric materials (for example, cable insulation and jackets, elastomeric seals, polymeric coatings, gaiters) which are used in environments where they are exposed to radiation. The object of this part of IEC 60544 is to provide guidelines on the assessment of ageing in service. The approaches discussed cover ageing assessment programmes based on condition monitoring (CM), the use of equipment deposits in severe environments and sampling of real-time aged components.

  1. Advanced materials and biochemical processes for geothermal applications

    Kukacka, L.E.; van Rooyen, D.; Premuzic, E.T.

    1987-04-01

    Two Geothermal Technology Division (GTD)-sponsored programs: (1) Geothermal Materials Development, and (2) Advanced Biochemical Processes for Geothermal Brines, are described. In the former, work in the following tasks is in progress: (1) high temperature elastomeric materials for dynamic sealing applications, (2) advanced high temperature (300/sup 0/C) lightweight (1.1 g/cc) well cementing materials, (3) thermally conductive composites for heat exchanger tubing, (4) corrosion rates for metals in brine-contaminated binary plant working fluids, and (5) elastomeric liners for well casing. Methods for the utilization and/or the low cost environmentally acceptable disposal of toxic geothermal residues are being developed in the second program. This work is performed in two tasks. In one, microorganisms that can interact with toxic metals found in geothermal residues to convert them into soluble species for subsequent reinjection back into the reservoir or to concentrate them for removal by conventional processes are being identified. In the second task, process conditions are being defined for the encapsulation of untreated or partially biochemically treated residues in Portland cement-based formulations and the subsequent utilization of the waste fractions in building materials. Both processing methods yield materials which appear to meet disposal criteria for non-toxic solid waste, and their technical and economic feasibilities have been established.

  2. 金属波齿柔性石墨复合垫片蠕变-应力松弛性能研究%Characteristic study of creep-stress relaxation on flexible graphite corrugated metal gaskets

    郭滨诗; 姜敏夫; 刘金义

    2013-01-01

    The study showed that stress relaxation characteristic of gaskets has remarkable influence on reliability of bolt-flange linking system.The paper was in according to GB/T19066.3 test conditions to be testing for flexible graphite corrugated metal gaskets of standard D 65.5 mm×50.5 mm×2.5 mm,three various circular arc radius,wave gear distance and gear quantity,and found out the affection factor and regular on stress relaxation characteristic,to provide scientific basis for engineering practice.%垫片的蠕变-应力松弛特性对螺栓法兰密封连接系统的可靠性有显著的影响.作者按照GB/T19066.3的实验条件对标准规格为D 65.5 mm×50.5 mm×2.5mm 3种不同几何尺寸的金属(06Cr19Ni10+柔性石墨)波齿复合垫片进行蠕变-应力松弛实验研究,从而找出应力松弛特性影响因素及其规律,为工程实践提供科学指导.

  3. 发动机气缸密封垫压缩回弹性能测试技术研究%Research on the Testing Technology of Compression Recovery Performance of Engine Cylinder Seal Gasket

    王兴日; 田明

    2013-01-01

    This paper introduces the overall structure of the compression-resilience testing machine and describes the working principles of its system.The whole system is controlled by computer for loading and unloading,measures the deformation de-gree of the gasket by using the raster displacement sensor with high precision and realizes the automatic measurement on the two important parameters of compression rate and resilience rate of the engine cylinder gasket,which is proved to have high measurement precision and wide application prospect.%介绍了压缩回弹试验机的整体结构,表述了试验机系统的工作原理。整个系统通过计算机控制进行加载和卸载,利用高精度的光栅尺位移传感器测量垫片的变形量,实现了对发动机气缸密封垫的两个重要参数压缩率和回弹率的自动测量,测量精度较高,应用前景广泛。

  4. Sierpi ´nski图与Sierpi ´nski gasket图的条件着色∗%On r-hued Coloring of Sierpi ´nski Graphs and Sierpi ´nski Gasket Graphs

    宋兴坤; 梁晓东

    2015-01-01

    In this paper, the authors study r-hued coloring of Sierpi ´nski graphs and Sierpi ´nski gasket graphs, meanwhile, the authors give their r-hued chromatic number, respectively. For Sierpi´nski gasket graphs, when n > 2, χ1(Sn) =χ2(Sn)=3 andχ3(Sn)=4;if r>4, thenχr(Sn)=6. For Sierpi´nski graphs, when n>2, if 1 6 r 6 k−1, thenχr(S(n,k))=k;if r>k, thenχr(S(n,k))=k+1.%对Sierpi ´nski图与Sierpi ´nski gasket图的条件着色进行研究,分别给出其条件色数.对于Sierpi ´nski gasket图,当n>2时,χ1(Sn)=χ2(Sn)=3,χ3(Sn)=4,若r>4,则χr(Sn)=6.对于Sierpi´nski图,当n>2时,若16 r 6 k−1,则χr(S(n,k))=k;若r>k,则χr(S(n,k))=k+1.

  5. Study of Neural Network in the Classification of the Non- asbestos Gaskets%神经网络在非石棉垫片分类中的研究

    田槐艳; 刘美红; 王海飞

    2011-01-01

    A method of classification by using neural network to the known 15 kinds of the non -asbestos gaskets of formula data was proposed in this paper. By using the PNN( probabilistic neuralnetwork) ,LVQ( learning vector quantization) neural network and SOM ( self - organizing feature map) neural network respectively to classify the non - asbestos gaskets. The results indicate that the PNN neural network and LVQ neural network method based on the data that provided in the paper both can effectively classify,while SOM neural network can not classify them ideally.%提出运用神经网络的分类方法来对已知的15种非石棉垫片的配方数据进行分类.分别运用神经网络中的PNN,LVQ和SOM神经网络对其进行分类.结果表明,PNN神经网络和LVQ神经网络在所提供的数据中均能进行有效的分类,而SOM的分类结果则不太理想.

  6. Cryogenic loading of large volume presses for high-pressure experimentation and synthesis of novel materials

    Lipp, M J; Evans, W J; Yoo, C S

    2005-01-21

    We present an efficient easily implemented method for loading cryogenic fluids in a large volume press. We specifically apply this method to the high-pressure synthesis of an extended solid derived from CO using a Paris-Edinburgh cell. This method employs cryogenic cooling of Bridgman type WC anvils well insulated from other press components, condensation of the load gas within a brass annulus surrounding the gasket between the Bridgman anvils. We demonstrate the viability of the described approach by synthesizing macroscopic amounts (several milligrams) of polymeric CO-derived material, which were recovered to ambient conditions after compression of pure CO to 5 GPa or above.

  7. Remifentalino intravenoso mediante infusor elastomerico frente a meperidina intramuscular: Estudio comparativo en analgesia obstetrica Intravenous remifentanil delivered through an elastomeric device versus intramuscular meperidine comparative study for obstetric analgesia

    E. Calderón

    2006-10-01

    Full Text Available Objetivos: Evaluar la eficacia y seguridad de remifentanilo administrado mediante infusor elastomérico con PCA iv en analgesia obstétrica comparado con meperidina intramuscular en parturientas con contraindicación para analgesia epidural. Material y Método: Se seleccionaron aletoriamente 24 parturientas, se asoció infusor elastomérico Baxter® con 250 ml de suero fisiológico con 2,5 mg de remifentanilo y un ritmo de 12 ml·h ¹, lo que supone una infusión media de 0,025 μg·kg-1·min-1 de remifentanilo, permitiendo la administración de bolos de 5 ml con un tiempo de cierre de 30 minutos (Grupo R o 1 mg·kg¹ de meperidina y 2,5 mg de haloperidol (Grupo M vía intramuscular cada 4 h. Valoramos la intensidad del dolor cada 30 min mediante una escala analógica visual (EVA, tiempo de infusión, bolos administrados, el nivel de sedación mediante escala del estado de alerta y sedación evaluada por el observador (OAA/S, efectos adversos y el test de Apgar del recién nacido al minuto y a los 5 min. Resultados: No hubo diferencias en los datos antropométricos de ambos grupos. La duración media de la infusión en el grupo R fue de 280 ± 55 min y las necesidades de bolos de rescate de 1,2 ± 1,5. La dosis media de meperidina intramuscular en el grupo M fue de 120 ± 25 mg. La intensidad del dolor durante el parto fue significativamente menor en el grupo R durante todo el periodo de dilatación y expulsivo (pObjectives: To evaluate the effectiveness and security of remifentanil administered by means of elastomeric infusor with PCA IV compared obstetrical analgesia with intramuscular meperidine in obstetric patients with contraindication for epidural analgesia, Material and Method: 24 patients were randomized, an elastomeric infusor Baxter® with a capacity of 250 ml was filled with 2.5 mg of remifentanil and a 12 mililiter·h-1, was satarted, (average infusion of 0.025·kg-1·min-1 of remifentanil, and boluses of 5 ml with a time of closing

  8. Analgesia invasiva domiciliaria en el manejo del dolor postoperatorio en cirugía mayor ambulatoria mediante bombas elastoméricas intravenosas Home invasive analgesia in the management of postoperative pain alter outpatient major surgery using intravenous elastomeric pumps

    R. Rodríguez de la Torre

    2011-06-01

    los pacientes mostró un alto grado de satisfacción, un 16% de los pacientes satisfacción moderada y un 0,2% poca satisfacción. Conclusión: nuestro estudio demuestra la viabilidad y seguridad de la utilización de infusores elastoméricos endovenosos como método de analgesia postoperatoria, que permiten controlar los casos de dolor moderado a severo en procedimientos aplicados a la cirugía ambulatoria. Sin embargo se necesitan más estudios comparativos con técnicas analgésicas convencionales, así como con diferentes regímenes de infusión.Introduction: moderate to severe postoperative pain is still a problem in outpatient surgery, since it causes patient flow problems and delays the discharge of patients, being one of the major causes of re-hospitalization and hence a relevant quality indicator of these Units. The use of home invasive analgesic techniques, in all their regimes, can be effective for the management of postoperative pain in these surgical procedures and allow them to be included in outpatient surgery programs. Objectives: the aim of our study was to determine the feasibility and safety of the use of elastomeric continuous perfusion pumps for the administration of home continuous endovenous analgesia, as well as to assess analgesic effectiveness and degree of satisfaction of patients undergoing outpatient surgerys. Material and methods: we conducted a simple retrospective study in 463 patients. After the surgical procedure was performed under multimodal analgesia, two differents elastomeric endovenous pumps (dexketoprofeno pump or metamizol pump were used. Pain intensity by means of a visual analog scale and a plain oral scale, the need for supplemental analgesics. At home (24 hours after the surgical operation, the Home Care Unit checked side effects, sleep disorders, pain intensity, need of rescue analgesia and degree of satisfaction. Results: 69% of the patients report absence or slight pain 24 h after the surgical operation, just 16 out of

  9. Modular glovebox connector and associated good practices for control of radioactive and chemically toxic materials

    Design and associated good practices are described for a modular glovebox connector to improve control of radioactive and chemically toxic materials. The connector consists of an anodized aluminum circular port with a mating spacer, gaskets, and retaining rings for joining two parallel ends of commercially available or custom-manufactured glovebox enclosures. Use of the connector allows multiple gloveboxes to be quickly assembled or reconfigured in functional units. Connector dimensions can be scaled to meet operational requirements for access between gloveboxes. Options for construction materials are discussed, along with recommendations for installation of the connector in new or retrofitted systems. Associated good practices include application of surface coatings and caulking, use of disposable glovebags, and proper selection and protection of gasket and glove materials. Use of the connector at an inhalation toxicology research facility has reduced the time and expense required to reconfigure equipment for changing operational requirements, the dispersion of contamination during reconfigurations, and the need for decommissioning and disposal of contaminated enclosures

  10. 变压吸附装置均压阀密封片易损原因分析及解决办法%Reasons for easy damage of pressure equalizing valve gasket seals for PSA units and their solution

    赵天志; 黄贻弘

    2012-01-01

    针对变压吸附装置中均压阀密封片易损寿命短的问题,选取碟阀进行详细分析其失效原因.根据多年对阀门的研究以及变压吸附工程经验,对此提出解决办法.%The reasons for easy damage of the pressure equalizing valve gasket seals for pressure swing adsorption (PSA)units were analyzed with the butterfly valve as an example, and the solutions to the problem were proposed based on the long term research on valves and experiences in PSA engineering.

  11. 铸铁管道胶圈承插接口抗震性能试验研究%Experimental research on seismic capability of cast-iron pipe with rubber gasket joints

    陈春光; 杨庆华; 孔杰; 解晓杰; 廖倩

    2012-01-01

    Ductile cast iron pipe is a tubular product, which is frequently used in city water-supply project. The seismic capability of joints is one of the factors, which must be considered in the design of water-supply network in seismic areas. To study the mechanical parameters of rubber gasket joints, a series of prototype drawing experiment are performed lo investigate the regularity of joints drawing force and the joints displacement. The experimental results show that, rubber gasket joints for ductile cast iron pipe is favorable for earthquake-resistance; the allowed maximum joints displacement is about 3 ~4cm; the joints spring coefficient is between 32N/cm· cm-2 to 125 N/ cm ·cm-2and the maximum resistance is about 45 ~75N/cm2.%铸铁管道是城市供水工程常用的管材,其接口的抗震性能是地震多发地区供水管网设计必须考虑的因素之一.为研究胶圈承插接口的力学性能参数,采用了原型拉拔试验,测定了管道胶圈接口拉拔力与接口变形量,通过试验数据分析,证明了胶圈承插接口具有良好的抗震性能,接头最大允许变形量可达3~4cm,测定出铸铁管胶圈承插接口单位接触面积弹簧系数值在32~125N/(cm·cm2)之间、单位接触面积接头最大抗力为45~75N/cm2.

  12. 超高水压大直径盾构隧道管片接缝防水设计与试验研究%Design and experimental study on waterproof gasket of large-diameter shield tunnel under ultra high water pressure

    拓勇飞; 舒恒; 郭小红; 丁文其; 王建

    2013-01-01

    For the project of large-diameter shield tunnel under the highest water pressure in China,a set of design process and research method is proposed for the waterproof gasket for segrnent joints,and the related pattern is studied.First of all,based on the worldwide research progress,combined with the engineering characteristics,a double seal elastomer arrangement for segment joint waterproof gasket of large-diameter shield tunnel under the ultra high water pressure is determined.Secondly,the technical standard of waterproof is studied,and it lays the basis for further analysis of the elastic gasket design and experiment.Thirdly,comparative analysis of several sections of elastic seal gaskets is performed.Finally,a set of unique device and method is adopted,performing the experiments on the waterproof ability and assembly force of the gaskets,and through the comprehensive analysis of the experiment data,the optimal design scheme of the waterproof gasket for segment joint is determined.%针对目前国内承受水压最高的大直径盾构隧道工程,提出一套较系统的弹性密封垫设计流程与研究方法,研究该类管片接缝防水的规律.首先,基于国内外现有研究成果,结合工程特点,确定了超高水压大直径盾构管片接缝防水双道弹性体的布置方式;其次,对防水技术标准进行研究,为深入分析弹性密封垫的相关设计内容与试验成果奠定基础;再次,重点对弹性密封垫的断面形式进行多方案比选分析;最后,通过独特的试验系统与试验方法,对不同断面的弹性密封垫进行高水压防水能力试验以及密封垫装配力试验,综合分析试验成果,最终确定最优防水设计方案.

  13. Corrosion and stress corrosion cracking of bolting materials in light water reactors

    The primary coolant of a pressurized water reactor contains dissolved boric acid added as a soluble neutron absorber. Corrosion and stress corrosion cracking of bolts on pumps and on primary system manways have occurred where gaskets leak this boric acid onto the low alloy steel bolting material. Laboratory experiments have shown that the concentration of the boric acid to a moist paste at approximately the boiling point of water can produce corrosion rates of the order of several tenths of an inch per year on bolting and piping materials, which values are consistent with service experience. Frequently molybdenum disulfide is used as a lubricant for tightening bolts on massive flanges. Laboratory experience has shown that when the primary coolant leaks through a gasket the molybdenum disulfide can react with the leaking steam to produce hydrogen sulfide and subsequent stress corrosion cracking of the bolts. Additionally, contaminants concentrating over significant time periods have caused stress corrosion cracking failures of reactor coolant pump internals. Failure analysis of cracked bolts from service and the results of laboratory tests that demonstrate these mechanisms of bolt cracking are presented

  14. Survey of materials for hydrazine propulsion systems in multicycle extended life applications

    Coulbert, C. D.; Yankura, G.

    1972-01-01

    An assessment is presented of materials compatibility data for hydrazine monopropellant propulsion systems applicable to the Space Shuttle vehicle missions. Materials were evaluated for application over a 10-yr/100-mission operational lifetime with minimum refurbishment. A general materials compatibility rating for a broad range of materials and several propellants based primarily on static liquid propellant immersion testing and an in-depth evaluation of hydrazine decomposition as a function of purity, temperature, material, surface conditions, etc., are presented. The most promising polymeric material candidates for propellant diaphragms and seals appear to have little effect on increasing hydrazine decomposition rates, but the materials themselves do undergo changes in physical properties which can affect their 10-yr performance in multicycle applications. The available data on these physical properties of elastomeric materials as affected by exposure to hydrazine or related environments are presented.

  15. Percentual de degradação das forças liberadas por ligaduras elásticas Force decay rate of orthodontic elastomeric ligatures

    Emanoela Volles de Souza

    2008-04-01

    Full Text Available OBJETIVO: avaliar ligaduras elásticas da marca Morelli, dos tipos modular e bengala, nas cores cinza e cristal para determinação do percentual de degradação das forças geradas pelas mesmas. METODOLOGIA: as ligaduras elásticas foram estiradas em estiletes de aço inoxidável com diâmetro de 4mm, imersas em solução de saliva artificial a 37ºC, sendo a intensidade das forças liberadas medidas nos tempos de zero hora, 24 horas, 1 semana, 2 semanas, 3 semanas e 4 semanas, em máquina de ensaios de tração. RESULTADOS E CONCLUSÕES: as ligaduras do tipo bengala liberaram, em média e no período de 4 semanas, maior intensidade de força que as do tipo modular. O percentual de degradação das forças liberadas por todas as ligaduras aumentou de forma acentuada entre zero e 24 horas e de forma gradativa após este período, com exceção do 28º dia quando, provavelmente, houve perda das propriedades elásticas das ligaduras. Não foi observado um comportamento constante das ligaduras bengala e modular em relação às cores cinza e cristal.PURPOSE: to evaluate gray and clear module and cane-loaded elastomeric ligatures of the brand Morelli to determine the percentage of decay of the forces they deliver. METHODS: the elastomeric ligatures were stretched over 4mm diameter stainless steel dowels and placed in synthetic saliva bath at 37ºC. The intensity of the forces delivered were taken at start, after 24 hours, one week, two weeks, three weeks and four weeks at a tensile test machine. RESULTS AND CONCLUSIONS: the cane-loaded ligatures delivered, in a period of 4 weeks, in average, greater force intensity than the modules. The percentage of force decay of all ligatures increased rapidly between zero and 24 hours and gradually after that period, except for the 28th day, when probably there was a loss of elastic properties of the ligatures. The researchers did not note any constant behavior in the cane-loaded and module ligatures in relation

  16. Outgassing tests on materials used in the DIII-D magnetic fusion tokamak

    In order to achieve high performance plasma discharges in the DIII-D magnetic fusion tokamak, impurity levels must be carefully controlled. Since first wall materials can desorb volatile impurities during these discharges, it is important to characterize and control the outgassing of these materials. An outgassing chamber was built to measure the outgassing properties of various materials used in the DIII-D vessel. The results of pump-down tests performed on ATJ graphite, thin Grafoil reg-sign gaskets, and MgO coaxial cables will be presented. In addition to pumpdown tests it was desired to study the behavior of the materials at temperatures up to 400 C, which is the maximum temperature to which the DIII-D vessel is baked. The station was modified to include independent heating control of the sample and a simple load-lock chamber

  17. The influence of filler on the properties of elastomeric materials based on poly(ethylene-co-propylene-co-2-ehylidene-5-norbornene rubber

    Budinski-Simendić Jaroslava

    2006-01-01

    Full Text Available Crosslinked samples based on poly(ethylene-co-propylene-co-2-ehylidene5-norbornene EPDM rubber, carbon black as active filler and natural chalk as inactive filler were cured with sulphur. The content of carbon black was varied from 100 to 200 pph. The content of chalk was varied from 0 to 100 pph. The content of paraffin oil was also varied in some samples. The compounds were prepared by mixing ingredients on a laboratory two-roll mill. Vulcanizates were prepared by curing at 180°C. Various methods were used for the physical and mechanical characterizations. The dynamic mechanical properties of the elastomers were measured in the temperature range from -120 to 80°C.

  18. Ultra-high-precision alignment of the elastomerically mounted elements of the science camera lenses for the Mars Science Laboratory (MSL) rover

    Cameras built for space exploration are required to meet stringent environmental conditions, such as thermal and dynamic loads for both the optics (camera lens) and imaging electronics. On a multitude of spaceborne imaging instruments, optical elements are supported in their mounts via an elastomeric bonding approach using a room temperature vulcanizing silicone as the bonding agent. Employing this integration method, we achieved element-to-element alignment, measured as the total indicated runout, using a high-precision contact probe to be on the order of half a wavelength of He-Ne laser light, or 0.3 μm, on the Malin Space Science Systems lenses for the Mars Science Laboratory (MSL) cameras. This is a higher precision than the current industry state-of-the-art, and it was achieved for the very challenging small diameter lens elements. This paper describes the design philosophy, implementation, and integration method that resulted in achieving this level of precision for interelement alignment. The results are based on actual measurements that were made during the process of building the MSL rover's science camera lenses, namely Mastcams, the Mars Hand Lens Imager, and the Mars Descent Imager. The optical designs of these cameras lenses are described in detail in [Opt. Eng.48, 103002 (2009)10.1117/1.3251343], while further information on the four science cameras can be found at http://www.msss.com.

  19. W形柔性石墨金属缠绕垫片结构及工艺参数优化试验研究%Experimental Study on Structure and Technology Parameter Optimization of Flexible Graphite Metal Spiral Wound Gasket of W-shape

    陈庆; 甘树坤; 刘兴德; 刘彦辰

    2014-01-01

    The elastic deformation formula was established through the mechanical model and theoretical analysis.Using the national standard 4.5 mm thickness of winding gasket as a benchmark,three kinds of W-shaped steel band structures were designed respectively with different width of flat steel belt.The compression-recovery performance of the flexible graphite metal spiral wound gasket with different W-shaped steel band structures was studied under different coil compres-sion force and tension force through orthogonal experiments,and the best combination performance parameters of the flexi-ble graphite metal spiral wound gasket were obtained.%通过力学模型和理论分析,建立W形柔性石墨金属缠绕垫片弹性变形公式。以国家标准中4.5 mm厚度的缠绕垫片为基准,分别用不同宽度的平钢带设计出3种W形钢带结构,并通过正交试验研究不同W形钢带结构的柔性石墨内外环缠绕垫片在不同缠绕压紧力和拉紧力时的压缩-回弹性能,得到性能最佳的参数组合。

  20. GC-MS法测定食品包装用塑料垫圈及与其接触的食品中邻苯二甲酸酯类物质含量%Determination of phthalate esters in plastic gasket used in food package and the food inside by GC-MS

    郝景雯; 张金鹏; 杨向辉

    2014-01-01

    采用超声波萃取-气质联用法测定食品包装用塑料垫圈中5种邻苯二甲酸酯(PAEs)的含量, PAEs添加回收率在83.9%~107.8%之间,标准偏差在1.5%~6.1%之间;此外,对其中包装容器内的食品也进行了检测。结果表明:GC-MS法可以对塑料垫圈中的邻苯二甲酸酯进行定性定量分析,样品垫圈均被检出含有PAEs增塑剂成分,且由于溶出迁移,对所接触的食品造成了不同程度的污染。%Phthalate esters in plastic gasket used in food package was determinate by ultrasonic solvent extraction and gas chromatography-mass spectrometry (GC-MS). The recoveries of phthalate esters (PAEs) were from 83.9% to 107.8%, and RSD were from 1.5%to 6.1%. Results showed that PAEs in Plastic Gasket could be identified and quan-tified by GC-MS. PAEs Plasticizer were detected in the plastic gaskets, and the foods inside were also contaminated by PAEs because of the migration.

  1. Type B plutonium transport package development that uses metallic filaments and composite materials

    A new package was developed for transporting Pu and U quantities that are currently carried in DOT-6M packages. It uses double containment with threaded closures and elastomeric seals. A composite overpack of metallic wire mesh and ceramic or quartz cloth insulation is provided for protection in accidents. Two prototypes were subjected to dynamic crush tests. A thermal computer model was developed and benchmarked by test results to predict package behavior in fires. The material performed isotropically in a global fashion. A Type B Pu transport package can be developed for DOE Pu shipments for less than $5000 if manufactured in quantity. 5 figs, 6 refs

  2. Type B plutonium transport package development that uses metallic filaments and composite materials

    Pierce, J. D.; Moya, J. L.; McClure, J. D.; Hohnstreiter, G. F. [Sandia National Labs., Albuquerque, NM (United States); Golliher, K. G. [USDOE Albuquerque Operations Office, NM (United States)

    1991-01-01

    A new package was developed for transporting Pu and U quantities that are currently carried in DOT-6M packages. It uses double containment with threaded closures and elastomeric seals. A composite overpack of metallic wire mesh and ceramic or quartz cloth insulation is provided for protection in accidents. Two prototypes were subjected to dynamic crush tests. A thermal computer model was developed and benchmarked by test results to predict package behavior in fires. The material performed isotropically in a global fashion. A Type B Pu transport package can be developed for DOE Pu shipments for less than $5000 if manufactured in quantity. 5 figs, 6 refs. (DLC)

  3. 碱锰电池尼龙密封圈爆破压力测试影响因素探究%Study on the influence factors in the test of burst pressure of nylon gasket for alkaline Zn-MnO2 battery

    李海波; 邹快乐

    2014-01-01

    通过对碱锰电池尼龙密封圈爆破压力测试环境、测试方法等因素的选择与改变,研究了密封圈测试前热处理温度、热处理时间、测试前晾晒时间以及测试环境温度、湿度等因素对尼龙密封圈爆破压力测试值的影响。研究结果表明,热处理温度越高,热处理时间越长,测试值越低;晾晒时间越长,测试值越高;测试温度越高,测试值越低;测试湿度越高,测试值越低。对各因素产生的结果进一步研究,并结合实验发现,各因素的变化对尼龙材料的内部水分造成了影响,也导致测试值的变化。%With the changes of test environment and test methods for burst pressure of alkaline manganese battery nylon gasket,the influences of the heat treatment temperature,heat treat-ment time,drying time before test and test environment factors such as temperature or humidity on the test results are studied.Results show that the higher the heat treatment temperature and the longer the heat treatment time,the lower the test values;the longer the drying time,the higher the test values;the higher the testing temperature,the lower the test values;the higher the test humidity,the lower the test values.After the further study on the effects of various fac-tors and combined with the experiments’results,it is found that the change of the factors would affect the internal moisture of the nylon material,and then lead to the change of test values.

  4. Long term Integrity of Spent Fuel and Construction Materials and Behaviour of Components for Dry Storage Facilities

    In Japan, two dry storage facilities at TEPCO and JAPCO sites have been in operation since 1995 and 2002 respectively. The TEPCO dry storage facility was damaged by a Tsunami attack on 11th March 2011. The casks stored in the facility have since been moved to an onsite temporary cask custody area; after confirmation of the integrity of casks. On the other hand, the Tsunami did not attack the dry storage facility at the JAPCO site. The integrity of the storage building and the casks were maintained. In addition, an off-site centralized dry storage facility has been constructed at Mutsu City. Operation of the storage facility is pending a safety re-examination against new safety regulations. Its final storage capacity will be 5000 t(U) and the storage period is up to 50 years. To support storage operations, it is therefore necessary to obtain and evaluate data on the integrity of spent fuels and cask construction materials during long term dry storage. Objectives: Construction materials for dry storage facilities: • To evaluate long-term reliability of welded stainless steel canisters under stress corrosion cracking (SCC) environment, including the critical salt density deposited on the canister to initiate SCC, monitoring, prevention, and the mitigation method of SCC; • To detect and analyze the cover gas leak from canisters; • To evaluate integrity of sealability of metal gasket under long term storage; • To evaluate influence of the vibration on sealing performance of the ageing gasket

  5. Experimental Study on Stress Relaxation of Flexible Graphite Corrugated Metal Gaskets%柔性石墨金属波齿复合垫片应力松弛特性试验研究

    陈庆; 陈利强

    2013-01-01

    According to GB/T 19066.3 test specifications,the experiment on stress relaxation of the flexible graphite corrugated metal gaskets which boasting of φ65.5mm × 50.5mm × 2.5mm in size,three different arc radiuses,wave pitches and number of teeth was implemented so that the factors influencing the stress relaxation can be obtained to guide engineering practice scientifically.%按照GB/T 19066.3的试验条件对标准规格为φ65.5mm×50.5mm×2.5mm、具有3种不同的圆弧半径、波齿距和齿数的柔性石墨金属(柔性石墨+ 06Cr19Ni10)波齿复合垫片进行应力松弛试验,找出应力松弛特性影响因素及其规律,为工程实践提供科学指导.

  6. Use of a sub-gasket and soft gas diffusion layer to mitigate mechanical degradation of a hydrocarbon membrane for polymer electrolyte fuel cells in wet-dry cycling

    Ishikawa, Hiroshi; Teramoto, Takeshi; Ueyama, Yasuhiro; Sugawara, Yasushi; Sakiyama, Yoko; Kusakabe, Masato; Miyatake, Kenji; Uchida, Makoto

    2016-09-01

    The mechanical durability of hydrocarbon (HC) membranes, used for polymer electrolyte fuel cells (PEFCs), was evaluated by the United States Department of Energy (USDOE) stress protocol involving wet-dry cycling, and the degradation mechanism is discussed. The HC membrane ruptured in the edge region of the membrane electrode assembly (MEA) after 300 cycles due to a concentration of the mechanical stress. Post-test analysis of stress-strain measurements revealed that the membrane mechanical strain decreased more than 80% in the edge region of the MEA and about 50% in the electrode region, compared with the pristine condition. Size exclusion chromatography (SEC) indicated that the average molecular weight of the HC polymer increased slightly, indicating some cross-linking, while the IEC decreased slightly, indicating ionomer degradation. As a result of two types of modifications, a sub-gasket (SG) and a soft gas diffusion layer (GDL) in the MEA edge region, the mechanical stress decreased, and the durability increased, the membrane lasting more than 30,000 cycles without mechanical failure.

  7. Comparison of Raman spectroscopy vs. high performance liquid chromatography for quality control of complex therapeutic objects: model of elastomeric portable pumps filled with a fluorouracil solution.

    Bourget, Philippe; Amin, Alexandre; Vidal, Fabrice; Merlette, Christophe; Lagarce, Frédéric

    2014-03-01

    This study compares the performance of a reference method of HPLC to Raman spectroscopy (RS) for the analytical quality control (AQC) of complex therapeutic objects. We assessed a model consisting of a widely used anticancer drug, i.e., 5-fluorouracil, which was compounded in a complex medical device, i.e., an elastomeric portable infusion pump. In view of the main objective, the two methods provided excellent results for the analytical validation key criteria, i.e., trueness, precision and accuracy, ranging from 7.5 to 50mg/mL and in either isotonic sodium or 5% dextrose. The Spearman and Kendall correlation tests (p-value<1×10(-15)) and the statistical studies performed on the graphs confirm a strong correlation in the results between RS and the standard HPLC under the experimental conditions. The selection of a spectral interval between 700 and 1400cm(-1) for both the characterization and quantification by RS was the result of a gradual process optimization, combining matrix and packaging responses. In this new application, we demonstrate at least eight benefits of RS: (a) operator safety, (b) elimination of disposables, (c) elimination of analysis waste, which contributes to the protection of the environment, (d) a fast analytical response of less than 2min, (e) the ability to identify the solubilizing phase, (f) reduction of the risk of errors because no intrusion or dilution are needed, (g) negligible maintenance costs and (h) a reduction in the budget dedicated to technician training. Overall, we indicate the potential of non-intrusive AQC performed by RS, especially when the analysis is not possible using the usual techniques, and the technique's high potential as a contributor to the safety of medication. PMID:24463044

  8. Micromechanics and constitutive models for soft active materials with phase evolution

    Wang, Binglian

    Soft active materials, such as shape memory polymers, liquid crystal elastomers, soft tissues, gels etc., are materials that can deform largely in response to external stimuli. Micromechanics analysis of heterogeneous materials based on finite element method is a typically numerical way to study the thermal-mechanical behaviors of soft active materials with phase evolution. While the constitutive models that can precisely describe the stress and strain fields of materials in the process of phase evolution can not be found in the databases of some commercial finite element analysis (FEA) tools such as ANSYS or Abaqus, even the specific constitutive behavior for each individual phase either the new formed one or the original one has already been well-known. So developing a computationally efficient and general three dimensional (3D) thermal-mechanical constitutive model for soft active materials with phase evolution which can be implemented into FEA is eagerly demanded. This paper first solved this problem theoretically by recording the deformation history of each individual phase in the phase evolution process, and adopted the idea of effectiveness by regarding all the new formed phase as an effective phase with an effective deformation to make this theory computationally efficient. A user material subroutine (UMAT) code based on this theoretical constitutive model has been finished in this work which can be added into the material database in Abaqus or ANSYS and can be easily used for most soft active materials with phase evolution. Model validation also has been done through comparison between micromechanical FEA and experiments on a particular composite material, shape memory elastomeric composite (SMEC) which consisted of an elastomeric matrix and the crystallizable fibre. Results show that the micromechanics and the constitutive models developed in this paper for soft active materials with phase evolution are completely relied on.

  9. Novel nanocomposite technologies for dynamic monitoring of structures: a comparison between cement-based embeddable and soft elastomeric surface sensors

    Ubertini, Filippo; Laflamme, Simon; Ceylan, Halil; Materazzi, Annibale Luigi; Cerni, Gianluca; Saleem, Hussam; D'Alessandro, Antonella; Corradini, Alessandro

    2014-04-01

    The authors have recently developed two novel solutions for strain sensing using nanocomposite materials. While they both aim at providing cost-effective solutions for the monitoring of local information on large-scale structures, the technologies are different in their applications and physical principles. One sensor is made of a cementitious material, which could make it suitable for embedding within the core of concrete structures prior to casting, and is a resistor, consisting of a carbon nanotube cement-based transducer. The other sensor can be used to create an external sensing skin and is a capacitor, consisting of a flexible conducting elastomer fabricated from a nanocomposite mix, and deployable in a network setup to cover large structural surfaces. In this paper, we advance the understanding of nanocomposite sensing technologies by investigating the potential of both novel sensors for the dynamic monitoring of civil structures. First, an in-depth dynamic characterization of the sensors using a uniaxial test machine is conducted. Second, their performance at dynamic monitoring of a full-scale concrete beam is assessed, and compared against off-the-shelf accelerometers. Experimental results show that both novel technologies compare well against mature sensors at vibration-based structural health monitoring, showing the promise of nanocomposite technologies for the monitoring of large-scale structural systems.

  10. An in vitro comparison of the force decay generated by different commercially available elastomeric chains and NiTi closed coil springs Comparação in vitro da degradação da força gerada por cadeias elastoméricas e por molas fechadas de NiTi de diferentes marcas comerciais

    Ana Cristina Soares Santos; André Tortamano; Sandra Regina Frazatto Naccarato; Gladys Cristina Dominguez-Rodriguez; Julio Wilson Vigorito

    2007-01-01

    This in vitro study was designed to compare the forces generated by commercially available elastomeric chains and NiTi closed coil springs, and to determine their force decay pattern. Forty elastomeric chains and forty NiTi closed coil springs were divided into 4 groups according to the following manufacturers: (1) Morelli®, (2) Abzil®, (3) TP Orthodontics® and (4) American Orthodontics®. The specimens were extended to twice their original length and stored in artificial saliva at 37°C. I...

  11. Frictional force released during sliding mechanics in nonconventional elastomerics and self-ligation: An in vitro comparative study

    Kumar, Davender; Dua, Vinay; Mangla, Rajat; Solanki, Ravinder; Solanki, Monika; Sharma, Rekha

    2016-01-01

    Aim and Objectives: The aim of this study is to evaluate the frictional forces generated by five different orthodontic brackets when used in combination with stainless steel (SS), titanium molybdenum alloy (TMA), and nickel-titanium (NiTi) archwires in dry conditions at physiological temperature. Materials and Methods: Five different types of maxillary upper right side self-ligating brackets (SLBs) (Damon 3MX, Smart Clip and Carriere LX) and conventional SS brackets (Mini 2000, Optimum Series and Victory Series) with a slot size 0.022 inch were coupled with 0.016” NiTi and 0.019 × 0.025” SS/titanium molybdenum alloy (TMA) archwires. Tests were carried out for each group of the bracket-wire combination at physiological temperature and in the dry state. Frictional forces were measured by Instron universal testing machine. Results: SLB showed lower fictional values in comparison with elastic ligatures. Frictional force increased proportionally to the wire size; TMA and NiTi archwires presented higher frictional resistance than SS archwires. Conclusion: SS brackets tied with conventional ligatures produced high and low friction when ligated with SLBs with passive clip. PMID:27433047

  12. Fabrication and characterization of elastomeric scaffolds comprised of a citric acid-based polyester/hydroxyapatite microcomposite

    Highlights: • Porous scaffolds were prepared from polymer/hydroxyapatite (POC/HA) composite. • The pore size was designed to be uniform for all POC/HA composite scaffolds. • Compression strength and modulus are dependent on HA concentration within composite. - Abstract: In this paper we describe an effective technical route for the production of porous scaffolds from microcomposite material consistent of citric acid-based polyester elastomer and hydroxyapatite microparticles with potential use in tissue engineering applications. Fabricated scaffolds were characterized by field emission electron microscopy, Fourier-transform infra-red spectroscopy, thermal gravimetric analysis and mechanical tests. We demonstrate that the chemical composition, scaffold morphology, mechanical integrity and porosity of the produced microcomposite scaffolds are strongly affected by variation of the initial hydroxyapatite concentration in the mineral-polymer mixture during the fabrication process. This polyester/mineral scaffold exhibits versatility in compression modulus and strength in the range of 21.72–33.25 KPa and 49.92–101.48 KPa respectively, corresponding to the hydroxyapatite concentration in the composite (10–30 wt.%)

  13. Replication of microchannel structures in WC-Co feedstock using elastomeric replica moulds by hot embossing process.

    Sahli, M; Gelin, J-C; Barrière, T

    2015-10-01

    Hot embossing is a net shaping process that is able to produce the micro-components of polymers with intrinsic and complex shapes at lower cost compared with machining and injection moulding. However, the emboss of hard metals, such as WC-Co, is more challenging due to their high thermal conductivity and ease of agglomeration. Thus, a WC-Co alloy mixed with a wax-based binder feedstock was selected. The formed feedstock exhibited pseudo-plastic flow and was successfully embossed (green part). Here, we developed a novel process that is used to replicate polymer microfluidic chips while simultaneously reducing the channel surface roughness of the mould insert, yielding optical-grade (less than 100 nm surface roughness) channels and reservoirs. This paper concerns the replication of metallic microfluidic mould inserts in WC-Co and the parameters associated with feedstock formation via a hot embossing process. A suitable formulation for micro-powder hot embossing has been established and characterised by thermogravimetric analyses and measurements of mixing torques to verify and quantify the homogeneity of the proposed feedstocks. The relative density of the samples increased with processing temperature, and almost fully dense materials were obtained. In this work, the effects of the sintering temperature on the physical properties were systematically analysed. The evolution of the metal surface morphology during the hot embossing process was also investigated. The results indicate that the feedstock can be used to manufacture micro-fluidic die mould cavities with a low roughness, proper dimensions and good shape retention. The shrinkage of the sintered part was approximately 19-24% compared with that of the brown part. PMID:26117760

  14. 关于船用垫片禁用石棉的探讨%Discussion on Asbestos Being Banned in Marine Gasket

    徐营杰; 徐燕铭; 滕宪斌

    2012-01-01

    Asbestos is always the darling of shipbuilding industry. But it becomes a kind of unwelcome material since the birth of more and more stringent environmental protection conventions, which should cause the attention of shipyards or dockyards. According to the asbestos problem found in one inspection carried by Australian environment protection bureau, this paper gives a brief discussion on asbestos material and proposed substitute materials.%随着越来越严格的环保公约的颁布与实施,曾广泛使用的石棉已经成为一种不受欢迎的材料,对此各大造船厂或者修船厂应引起注意文章针对天津新河船舶重工有限公司(以下简称“公司”)在一次澳大利亚环境保护局的检查过程中发现的石棉问题,对石棉材料相关问题进行了探讨,并提出了替代材料的建议

  15. Correlation of electrical reactor cable failure with materials degradation

    Complete circuit failure (shortout) of electrical cables typically used in nuclear power plant containments is investigated. Failure modes are correlated with the mechanical deterioration of the elastomeric cable materials. It is found that for normal reactor operation, electrical cables are reliable and safe over very long periods. During high temperature excursions, however, cables pulled across corners under high stress may short out due to conductor creep. Severe cracking will occur in short times during high temperatures (>1500C) and in times of the order of years at elevated temperatures (1000C to 1400C). A theoretical treatment of stress distribution responsible for creep and for cracking by J.E. Reaugh of Science Applications, Inc. is contained in the Appendix. 29 refs., 32 figs

  16. Open-access dielectric elastomer material database

    Vertechy, R.; Fontana, M.; Stiubianu, G.; Cazacu, M.

    2014-03-01

    Dielectric Elastomer Transducers (DETs) are deformable capacitors that can be used as sensors, actuators and generators. The design of effective and optimized DETs requires the knowledge of a set of relevant properties of the employed Dielectric Elastomer (DE) material, which make it possible to accurately predict their electromechanical dynamic behavior. In this context, an open-access database for DE materials has been created with the aim of providing the practicing engineer with the essential information for the design and optimization of new kinds of DET. Among the electrical properties, dielectric susceptibility, dielectric strength and conductivity are considered along with their dependence on mechanical strain. As regards mechanical behavior, experimental stress-strain curves are provided to predict hyperelasticity, plasticity, viscosity, Mullins effect and mechanical rupture. Properties of commercial elastomeric membranes have been entered in the database and made available to the research community. This paper describes the instrumentations, experimental setups and procedures that have been employed for the characterization of the considered DE materials. To provide an example, the experimental data acquired for a commercially available natural rubber membrane (OPPO Band Red 8012) are presented.

  17. Performance characteristics of O-ring seals for radioactive material packages when subjected to extreme temperatures

    Performance requirements for radioactive material (RAM) packages are specified in Title 10, Code of Federal Regulations, Part 71 (10CFR71). Seals that provide the containment system interface between the packaging body and closure must function in both high and low temperature environments which are characteristic of the hypothetical fire accident and the -40F (233 K)1 normal transport condition, respectively. A research and testing program has been initiated at Sandia National Laboratories to examine the performance of elastomeric O-ring seal materials commonly used in RAM packages during the temperature extremes. Performance characteristics including permeation times, static compression set, and leakage rate versus temperature and time are being examined using helium or neon as the tracer gas. The results of this study can be used as an aid to package designers when selecting O-ring seal materials for specific applications

  18. Experimental performance of an ablative material as an external insulator for a hypersonic research aircraft

    Puster, R. L.; Chapman, A. J.

    1977-01-01

    An ablative material composed of silica-filled elastomeric silicone was tested to evaluate its thermal and structural performance as an external insulator, or heat shield, for a hypersonic research aircraft. The material was also tested to determine whether it would form a durable char layer when initially heated and thereafter function primarily as an insulator with little further pyrolysis or char removal. Aerothermal tests were representative of nominal Mach 6 cruise conditions of the aircraft, and additional tests were representative of Mach 8 cruise and interference heating conditions. Radiant heating tests were used to simulate the complete nominal Mach 6 surface-temperature history. The silica char that formed during aerothermal tests was not durable. The char experienced a general and preferential surface recession, with the primary mechanism for char removal being erosion. Tests revealed that radiant heating is not a valid technique for simulating aerodynamic heating of the material.

  19. Development of thermoradiation technology of making of aggressiveproof elastomer materials for oil industry

    Full text: At present in oil industry is used elastomer materials (EM) on base of butadiene-nitrile caoutchouc (BNC). In most cases EM made from BNC, especially diaphragms, gasket rings and glands are destructed after shortly exploitation in aggressive liquid mediums, at result of the structure of EM contenting caoutchouc matter, accelerators plasticizer, antioxidant and other ingredients have some changes. So in factories of rubber and oil industry there are a lot of used EM on base of BNC. The problem of returning to balance expensive and deficit materials has a high economical, technological and ecological significance. At the Institute of radiation Problems of NAS of Azerbaijan is developed thermo radiation method of vulcanization of EM on base of BNC using γ-irradiation of Co60.This method has a significance advantage on comparison thermochemical method and allows to get the product of high quality. EM can be obtained with predicted properties by changing of absorbed dose of radiation, at this is ensured obtaining of C-C connection without application of sulfur and sulfur contenting accelerators. Instead is recommended polychalogenmethylcontenting (PCM) and epoxy compounds (EC) with oxides of metals. A wide laboratory testing of PCM and EC showed, that entering these structuring systems to gasket and gland mixtures is purposeful. On technological and exploitation properties the model are comparable with factory made products. It is suggested to use thermo radiation EM in engineering industry. The developed method allows to exclude environment pollution. Properties of thermo radiated vulcanizate depend on vulcanization structure and absorbed dose. The technological scheme of obtaining of use thermo radiation EM includes mixing heating in electropress during 2-4 min, radiation and other operations

  20. Accuracy of stone casts obtained by different impression materials

    Adriana Cláudia Lapria Faria

    2008-12-01

    Full Text Available Several impression materials are available in the Brazilian marketplace to be used in oral rehabilitation. The aim of this study was to compare the accuracy of different impression materials used for fixed partial dentures following the manufacturers' instructions. A master model representing a partially edentulous mandibular right hemi-arch segment whose teeth were prepared to receive full crowns was used. Custom trays were prepared with auto-polymerizing acrylic resin and impressions were performed with a dental surveyor, standardizing the path of insertion and removal of the tray. Alginate and elastomeric materials were used and stone casts were obtained after the impressions. For the silicones, impression techniques were also compared. To determine the impression materials' accuracy, digital photographs of the master model and of the stone casts were taken and the discrepancies between them were measured. The data were subjected to analysis of variance and Duncan's complementary test. Polyether and addition silicone following the single-phase technique were statistically different from alginate, condensation silicone and addition silicone following the double-mix technique (p .05 to alginate and addition silicone following the double-mix technique, but different from polysulfide. The results led to the conclusion that different impression materials and techniques influenced the stone casts' accuracy in a way that polyether, polysulfide and addition silicone following the single-phase technique were more accurate than the other materials.

  1. Evaluation of Ion Exchange Materials in K Basin Floor Sludge and Potential Solvents for PCB Extraction from Ion Exchange Materials

    Approximately 73 m3 of heterogeneous solid material, ''sludge,'' (upper bound estimate, Packer 1997) have accumulated at the bottom of the K Basins in the 100 K Area of the Hanford Site. This sludge is a mixture of spent fuel element corrosion products, ion exchange materials (organic and inorganic), graphite-based gasket materials, iron and aluminum metal corrosion products, sand, and debris (Makenas et al. 1996, 1997). In addition, small amounts of polychlorinated biphenyls (PCBs) have been found. These small amounts are significant from a regulatory standpoint. Ultimately, it is planned to transfer the K Basins sludge to the Hanford double shell tanks (DSTs). Chemical pretreatment is required to address criticality issues and the destruction or removal of PCBs before the K Basin sludge can be transferred to the DSTs. Eleven technologies have been evaluated (Papp 1997) as potential pretreatment methods. Based on the evaluations and engineering studies and limited testing, Fluor Daniel Hanford recommended solvent washing of the K Basin sludge, followed by nitric acid dissolution and, potentially, peroxide addition (FDH 1997). The solvent washing (extraction) and peroxide addition would be used to facilitate PCB removal and destruction. Following solvent extraction, the PCBs could be distilled and concentrated for disposal as a low-level waste. The purpose of the work reported here was to continue investigating solvent extraction, first by better identifying the ion exchange materials in the actual sludge samples and then evaluating various solvents for removing the PCBs or possibly dissolving the resins. This report documents some of the process knowledge on ion exchange materials used and spilled in the K Basins and describes the materials identified from wet sieving KE Basin floor and canister sludge and the results of other analyses. Several photographs are included to compare materials and illustrate material behavior. A summary of previous tests on solvent

  2. Lightweight constructions made of polymer materials. Classes - applications - trends; Leichtbau mit polymeren Werkstoffen. Klassen - Anwendungen - Tendenzen

    Meij, A. [Fachhochschule Kaiserslautern (Germany)

    2000-07-01

    The properties of polymer (composite) materials can be tailored to the specific requirements in service. This tailoring offers sheer unnumerable variations of materials and processing methods. A classification scheme is introduced to reduce this number of possible variations to a limited group of essential characteristics. Typical consequences for the properties and the processing of this material variations are described. The classification scheme also reveals 'white spots' in the application of engineering plastics. Development of new materials and combinations can thus be initiated more target-oriented. Consequently fabric reinforced thermoplastics are regarded as an example to raise today's volume in high-end composites. Pros and cons of these fabric reinforced plastics are mentioned. It is shown, that a synergy between the 'classical' plastics processing technology of the one hand and the composites technology on the other hand can boost new applications of structural polymer parts. (orig.) [German] Die technische Entwicklung der Menschheit wird seit jeher von der Verfuegbarkeit geeigneter Werkstoffe mitbestimmt. Je nach Anforderung verlangen Konstrukteure Werkstoffe mit unterschiedlichen Eigenschaftsprofilen, z.B. steif und fest oder weich und fest. Am besten, es gaebe einen Werkstoff, dessen Eigenschaften in allen Hinsichten frei 'einstellbar' waeren. Polymere Werkstoffe erfuellen diesen Wunsch selbstverstaendlich nicht, dennoch erstrecken die durch Modifikation erreichbaren Kennwerte sich ueber einen ausserordentlich grossen Bereich. Betrachtet man die polymeren Schaeume, die Elastomere, die technischen Kunststoffe und die Faserverbundwerkstoffe zusammen, so erstrecken sich sowohl die Festigkeit als auch die Steifigkeit ueber vier Dekaden. Auch die Zaehigkeit und die Dichte koennen weitgehend frei variiert werden. In diesem Beitrag sollen nun weiter einige Gedanken zum Eigenschafts-, Anwendungs- und Verarbeitungsprofil von

  3. Space Environment Effects on Silicone Seal Materials

    deGroh, Henry C., III; Daniels, Christopher C.; Dever, Joyce A.; Miller, Sharon K.; Waters, Deborah L.; Finkbeiner, Joshua R.; Dunlap, Patrick H.; Steinetz, Bruce M.

    2010-01-01

    A docking system is being developed by the NASA to support future space missions. It is expected to use redundant elastomer seals to help contain cabin air during dockings between two spacecraft. The sealing surfaces are exposed to the space environment when vehicles are not docked. In space, the seals will be exposed to temperatures between 125 to -75 C, vacuum, atomic oxygen, particle and ultraviolet radiation, and micrometeoroid and orbital debris (MMOD). Silicone rubber is the only class of space flight-qualified elastomeric seal material that functions across the expected temperature range. NASA Glenn has tested three silicone elastomers for such seal applications: two provided by Parker (S0899-50 and S0383-70) and one from Esterline (ELA-SA-401). The effects of atomic oxygen (AO), UV and electron particle radiation, and vacuum on the properties of these three elastomers were examined. Critical seal properties such as leakage, adhesion, and compression set were measured before and after simulated space exposures. The S0899-50 silicone was determined to be inadequate for extended space seal applications due to high adhesion and intolerance to UV, but both S0383-70 and ELA-SA-401 seals were adequate.

  4. Grant Writing without Blowing a Gasket

    Vandenbroek, Alicia

    2010-01-01

    In today's economic downturn budget cut is becoming more and more common. Even libraries seen as a vital part of the educational process are subject to reductions because districts are suffering financially. The answer? Grants. They aren't a perfect solution, but there is a lot of financial support available for those who ask. Besides the monetary…

  5. Materials selection guidelines for geothermal power systems. First edition

    DeBerry, D.W.; Ellis, P.F.; Thomas, C.C.

    1978-09-01

    Nine potential power cycles are defined and diagrammed for the generation of electricity from geothermal fluids. General fluid properties that influence the applicability of power cycles to a particular geothermal resource are discussed. The corrosivity of individual process streams in power cycles is described based on variations in chemical composition and temperature. Results of materials performance tests are analyzed based on the chemical composition of the corrosive medium and physical factors such as temperature, duration of exposure, and fluid velocity. The key chemical components in geothermal fluids that are significant in determining corrosivity are identified. Both summarized and detailed results of materials performance tests in U.S. liquid-dominated resources are given. Seven U.S. liquid-dominated KGRA's are classified according to relative corrosiveness and their key chemical components are defined. The various forms and mechanisms of corrosive attack that can occur in geothermal process streams are described. The application of nonmetallic materials in geothermal environments is discussed. The appendices contain information on (1) operating experience at geothermal power plants, (2) corrosion in desalination facilities, (3) reliability of geothermal plants, (4) elastomeric materials, (5) comparative alloy costs, and (6) geothermal equipment manufacturers. (MHR)

  6. Compatibility of refrigerants and lubricants with elastomers

    Hamed, G.R.; Seiple, R.H.

    1992-10-01

    Information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. 97% of the swell measurements have been made to date. The other 3% of the measurements are contingent on the availability of additional quantities of R-32. Swell behavior in the fluids have been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 hours and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

  7. Compatibility of refrigerants and lubricants with elastomers. Quarterly report, 1 July 1992--30 September 1992

    Hamed, G.R.; Seiple, R.H.

    1992-10-01

    Information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. 97% of the swell measurements have been made to date. The other 3% of the measurements are contingent on the availability of additional quantities of R-32. Swell behavior in the fluids have been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 hours and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

  8. Compatibility of refrigerants and lubricants with elastomers. Quarterly report, 1 October 1992--30 December 1992

    Hamed, G.R.; Seiple, R.H.

    1993-01-01

    The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. 97% of the swell measurements have been made to date. The other 3% of the measurements are contingent on availability of additional R-32. Swell behavior in the fluids have been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

  9. Compatibility of refrigerants and lubricants with elastomers

    Hamed, G.R.; Seiple, R.H.

    1993-01-01

    The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. 97% of the swell measurements have been made to date. The other 3% of the measurements are contingent on availability of additional R-32. Swell behavior in the fluids have been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

  10. Compatibility of refrigerants and lubricants with elastomers. Final report

    Hamed, G.R.; Seiple, R.H.; Taikum, Orawan

    1994-01-01

    The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. In part I of the program the swell behavior in the test fluids has been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 and 24 hours for samples removed fro the refrigerant test fluids and 24 hours after removal from the lubricants. Part II of the testing program includes the evaluation of tensile strength, hardness, weight, and dimensional changes after immersion aging in refrigerant/lubricant mixtures of selected elastomer formulations at elevated temperature and pressure.

  11. Mechanics of Re-Torquing in Bolted Flange Connections

    Gordon, Ali P.; Drilling Brian; Weichman, Kyle; Kammerer, Catherine; Baldwin, Frank

    2010-01-01

    It has been widely accepted that the phenomenon of time-dependent loosening of flange connections is a strong consequence of the viscous nature of the compression seal material. Characterizing the coupled interaction between gasket creep and elastic bolt stiffness has been useful in predicting conditions that facilitate leakage. Prior advances on this sub-class of bolted joints has lead to the development of (1) constitutive models for elastomerics, (2) initial tightening strategies, (3) etc. The effect of re-torque, which is a major consideration for typical bolted flange seals used on the Space Shuttle fleet, has not been fully characterized, however. The current study presents a systematic approach to characterizing bolted joint behavior as the consequence of sequentially applied torques. Based on exprimenta1 and numerical results, the optimal re-torquing parameters have been identified that allow for the negligible load loss after pre-load application

  12. Sustainable materials

    Allwood, Julian M.

    2016-01-01

    Materials influence every aspect of the energy system; therefore, as well as developing new materials for energy generation, materials scientists should engage in public debate about the limitations of future innovations and the conservation of existing materials.

  13. Characterisation of Materials used in Flex Bearings of Large Solid Rocket Motors

    CH.V. Ram Mohan

    2011-04-01

    Full Text Available Solid rocket motors are propulsion devices for both satellite launchers and missiles, which require guidance and steering to fly along a programmed trajectory and to compensate for flight disturbances. A typical solid rocket motor consists of motor case, solid propellant grain, motor insulation, igniter and nozzle. In most solid rocket motors, thrust vector control (TVC is required. One of the most efficient methods of TVC is by flex nozzle system. The flex nozzle consists of a flexible bearing made of an elastomeric material alternating with reinforcement rings of metallic or composite material. The material characterisation of AFNOR 15CDV6 steel and the natural rubber-based elastomer developed for use in flex nozzle are discussed. This includes testing, modelling of the material, selection of a material model suitable for analysis, and the validation of material model.Defence Science Journal, 2011, 61(3, pp.264-269, DOI:http://dx.doi.org/10.14429/dsj.61.52

  14. Effects of atomic oxygen on polymeric materials flown on EOIM-3

    Kamenetzky, Rachel R.; Linton, Roger C.; Finckenor, Miria M.; Vaughn, Jason A.

    1995-01-01

    Diverse polymeric materials, including several variations of Kapton, were flown on STS-46 as part of the Evaluation of Oxygen Interaction with Materials Experiment (EOIM-3). These materials were flown in the cargo bay and exposed to the space environment July 31 - August 8, 1992, including 40 hours of direct atomic oxygen impingement. The atomic oxygen exposure was approximately 2.2 x 10(exp 20) atoms/sq cm. Polymeric materials flown on EOIM-3 include coated and uncoated Kapton, Tefzel ETFE, Lexan, FEP and TFE Teflon, bulk Halar and PEEK, S383 silicone and Viton elastomeric seal material. Analyses performed included thickness measurements using Dektak and eddy current methods, mass loss, resistance, permeability, hardness, and FTIR. The effects of stress and the space environment on Kapton were also evaluated. Previous EOIM missions on STS-5 and STS-8 and the Long Duration Exposure Facility also contained polymeric material samples. Data from these previous flights are shown for comparison, as well as ground simulation of space environment effects using both thermal energy flow tubes and 5 eV neutral atomic oxygen beam facilities. Reaction efficiencies for the various atomic oxygen exposure conditions are discussed.

  15. Effects of atomic oxygen on polymeric materials flown on EOIM-3

    Kamenetzky, R.R.; Linton, R.C.; Finckenor, M.M.; Vaughn, J.A.

    1995-02-01

    Diverse polymeric materials, including several variations of Kapton, were flown on STS-46 as part of the Evaluation of Oxygen Interaction with Materials Experiment (EOIM-3). These materials were flown in the cargo bay and exposed to the space environment July 31 - August 8, 1992, including 40 hours of direct atomic oxygen impingement. The atomic oxygen exposure was approximately 2.2 x 10(exp 20) atoms/sq cm. Polymeric materials flown on EOIM-3 include coated and uncoated Kapton, Tefzel ETFE, Lexan, FEP and TFE Teflon, bulk Halar and PEEK, S383 silicone and Viton elastomeric seal material. Analyses performed included thickness measurements using Dektak and eddy current methods, mass loss, resistance, permeability, hardness, and FTIR. The effects of stress and the space environment on Kapton were also evaluated. Previous EOIM missions on STS-5 and STS-8 and the Long Duration Exposure Facility also contained polymeric material samples. Data from these previous flights are shown for comparison, as well as ground simulation of space environment effects using both thermal energy flow tubes and 5 eV neutral atomic oxygen beam facilities. Reaction efficiencies for the various atomic oxygen exposure conditions are discussed.

  16. Measurement of surface acoustic wave velocity using phase shift mask and application on thin film of thermoelectric material

    Li, Dongyao; Zhao, Peng; Gunning, Noel; Johnson, David; Zhao, Ji-Cheng; Cahill, David

    2014-03-01

    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 and apply this method, in combination with conventional picosecond acoustics, to determine a subset of the elastic constants of thin films of semiconducting misfit layered compounds. SAWs with a wavelength of 700 nm are generated and detected using an elastomeric polydimethylsiloxane (PDMS) phase-shift mask which is fabricated using a commercially-available Si grating as a mold. The velocity of SAWs of [(SnSe)1.04]m[MoSe2]n synthesized by elemental reactants show subtle variations in their elastic constants as a function of m and n. Precise measurements of elastic constants will enable a better understanding of interfacial stiffness in nanoscale multilayers and the effects of phonon focusing on thermal conductivity.

  17. Electrospinning and crosslinking of low-molecular-weight poly(trimethylene carbonate-co-(L)-lactide) as an elastomeric scaffold for vascular engineering.

    Dargaville, Bronwin L; Vaquette, Cédryck; Rasoul, Firas; Cooper-White, Justin J; Campbell, Julie H; Whittaker, Andrew K

    2013-06-01

    The growth of suitable tissue to replace natural blood vessels requires a degradable scaffold material that is processable into porous structures with appropriate mechanical and cell growth properties. This study investigates the fabrication of degradable, crosslinkable prepolymers of l-lactide-co-trimethylene carbonate into porous scaffolds by electrospinning. After crosslinking by γ-radiation, dimensionally stable scaffolds were obtained with up to 56% trimethylene carbonate incorporation. The fibrous mats showed Young's moduli closely matching human arteries (0.4-0.8MPa). Repeated cyclic extension yielded negligible change in mechanical properties, demonstrating the potential for use under dynamic physiological conditions. The scaffolds remained elastic and resilient at 30% strain after 84days of degradation in phosphate buffer, while the modulus and ultimate stress and strain progressively decreased. The electrospun mats are mechanically superior to solid films of the same materials. In vitro, human mesenchymal stem cells adhered to and readily proliferated on the three-dimensional fiber network, demonstrating that these polymers may find use in growing artificial blood vessels in vivo. PMID:23416575

  18. Novel nanocomposite technologies for dynamic monitoring of structures: a comparison between cement-based embeddable and soft elastomeric surface sensors

    The authors have recently developed two novel solutions for strain sensing using nanocomposite materials. While they both aim at providing cost-effective solutions for the monitoring of local information on large-scale structures, the technologies are different in their applications and physical principles. One sensor is made of a cementitious material, which could make it suitable for embedding within the core of concrete structures prior to casting, and is a resistor, consisting of a carbon nanotube cement-based transducer. The other sensor can be used to create an external sensing skin and is a capacitor, consisting of a flexible conducting elastomer fabricated from a nanocomposite mix, and deployable in a network setup to cover large structural surfaces. In this paper, we advance the understanding of nanocomposite sensing technologies by investigating the potential of both novel sensors for the dynamic monitoring of civil structures. First, an in-depth dynamic characterization of the sensors using a uniaxial test machine is conducted. Second, their performance at dynamic monitoring of a full-scale concrete beam is assessed, and compared against off-the-shelf accelerometers. Experimental results show that both novel technologies compare well against mature sensors at vibration-based structural health monitoring, showing the promise of nanocomposite technologies for the monitoring of large-scale structural systems. (paper)

  19. Understanding Materials

    Katsioloudis, Petros J.

    2010-01-01

    Almost everything people have ever done has involved materials. Historical evidence indicates that "engineered materials" have been available and utilized for the benefit of humankind since the Neolithic period, beginning about 10,000 BC. Some of these materials have been in existence for thousands of years. At first, materials consisted of wood,…

  20. Materials Development

    Brian Tomlinson

    2005-01-01

    @@ Introduction Materials development is both a field of study and a practical undertaking. As a field it studies the principles and procedures of the design, implementation and evaluation and adaptation of language teaching materials, by teachers for their own classrooms and by materials writers for sale or distribution. Ideally these two aspects of materials development are interactive in that the theoretical studies inform and are informed by the development and use of classroom materials (e. g. Tomlinson 1998c).

  1. Long term integrity of spent fuel and construction materials for dry storage facilities

    In Japan, two dry storage facilities at reactor sites have already been operating since 1995 and 2002, respectively. Additionally, a large scale dry storage facility away from reactor sites is under safety examination for license near the coast and desired to start its operation in 2010. Its final storage capacity is 5,000tU. It is therefore necessary to obtain and evaluate the related data on integrity of spent fuels loaded into and construction materials of casks during long term dry storage. The objectives are: - Spent fuel rod: To evaluate hydrogen migration along axial fuel direction on irradiated claddings stored for twenty years in air; To evaluate pellet oxidation behaviour for high burn-up UO2 fuels; - Construction materials for dry storage facilities: To evaluate long term reliability of welded stainless steel canister under stress corrosion cracking (SCC) environment; To evaluate long term integrity of concrete cask under carbonation and salt attack environment; To evaluate integrity of sealability of metal gasket under long term storage and short term accidental impact force.

  2. Materials Chemistry

    Fahlman, Bradley D

    2011-01-01

    The 2nd edition of Materials Chemistry builds on the strengths that were recognized by a 2008 Textbook Excellence Award from the Text and Academic Authors Association (TAA). Materials Chemistry addresses inorganic-, organic-, and nano-based materials from a structure vs. property treatment, providing a suitable breadth and depth coverage of the rapidly evolving materials field. The 2nd edition continues to offer innovative coverage and practical perspective throughout. After briefly defining materials chemistry and its history, seven chapters discuss solid-state chemistry, metals, semiconducting materials, organic "soft" materials, nanomaterials, and materials characterization. All chapters have been thoroughly updated and expanded with, for example, new sections on ‘soft lithographic’ patterning, ‘click chemistry’ polymerization, nanotoxicity, graphene, as well as many biomaterials applications. The polymer and ‘soft’ materials chapter represents the largest expansion for the 2nd edition. Each ch...

  3. Functional materials

    It is a compilation of chapters written by active researchers and offer information and critical insights about semiconducting materials and devices, dielectric and ferroelectric materials, magnetic materials, composites and other functional materials. In the book, the functional materials are discussed from the mixed valences and stoichiometry points of view, to understand the structural evolution and transformation of different material systems - in particular, the role played by crystal structures in property control of functional materials using advanced characterization techniques. The book examines the properties, soft-chemistry preparations, electronic structures and crystal structures of transition and rare earth metals and their oxides. The book presents a strong argument that functional materials system is the future direction of the multidisciplinary research involving physics, chemistry, materials science and electrical engineering, with emphasis on device applications. Papers relevant to INIS are indexed separately

  4. Contrast Materials

    ... adverse reaction, you should tell your doctor about: allergies to contrast materials, food, drugs, dyes, preservatives, or animals medications ... These include: previous adverse reactions to iodine-based contrast materials history of ... disease dehydration sickle cell anemia , polycythemia and ...

  5. Controle sismique d'un batiment en acier de 3 etages a l'echelle 1/3 par amortisseurs elastomeres et contreventements en chevron

    Gauron, Olivier

    This study develops an innovative configuration of seismic natural rubber dampers for multistory low- and medium-rise steel braced frames. The dampers are directly integrated in an horizontal position in the seismic force resisting system of the structure. They are connected in a series with typical chevron brace systems. This control system provides not only additional structural damping to the structure but also a period shift, acting in the same way as a base isolation system. First, the fiber reinforced natural rubber used in the application was tested. It exhibited strong non linear dependance of its equivalent viscoelastic properties related to the shear strain. Then, a 1/3-scale 3-story chevron braced steel frame with and without dampers was considered. The structure was build and placed on the shaking table of the University of Sherbrooke Structures Laboratory. Numerical studies show that the efficiency of the control system reduces strongly the seismic induced forces of the undamped structure without any amplification of displacement or drift. Obtained seismic response reduction levels represent significant safety and economical benefits for the proposed application. Finally, the control system viability is experimentally demonstrated by shaking table tests at different reduced seismic intensities. Non linear behavior of the structure due to non linear behavior of the damping material is highlighted, and the dependance of seismic control performances is shown to be related to seismic intensities. Results allow an extrapolation of the experimental control peformances tending to the numerical results at higher intensities. Key-words : chevron braces, damper, multistory building, natural rubber, seismic control, shaking table.

  6. Flourinated material

    Bozukova, Dimitriya; Jérôme, Christine; Pagnoulle, Christophe

    2009-01-01

    This invention relates to a method for modifying the surface of a material for use with a biological sample or tissue comprising the steps of providing a material having a surface which comprises reactive-functional groups; providing fluorinated molecules having reactive-functional groups complimentary to those on the material surface; using wet chemistry to attach the fluorinated molecules to the surface of the material by reacting the reactive-functional groups of the implant with the compl...

  7. Materials Engineering

    Fidancevska, Emilija; Srebrenkoska, Vineta

    2013-01-01

    The material presented in this book is the last part from the five books series which are resulte of the aforementioned project. Sustainable development, pariculary for industry was the base for developing of these educative materials. Part of the contents presented in the previous books covered the temas which generally are connected with sustainable development, but this book coveres the types of materials in general and the management of the waste materials. The nowdays f...

  8. Composite Materials

    Nielsen, Lauge Fuglsang

    This book deals with the mechanical and physical behavior of composites as influenced by composite geometry. "Composite Materials" provides a comprehensive introduction for researchers and students to modern composite materials research with a special emphasis on the significance of phase geometry....... The book enables the reader to a better understanding of the behavior of natural composites, improvement of such materials, and design of new materials with prescribed properties. A number of examples are presented: Special composite properties considered are stiffness, shrinkage, hygro...

  9. A new generation of sterile and radiopaque impression materials: an in vitro cytotoxicity study.

    Coppi, Chiara; Paolinelli Devincenzi, Chiara; Bortolini, Sergio; Consolo, Ugo; Tiozzo, Roberta

    2007-07-01

    Impression materials are largely used to record the geometry of dental tissue. Hence, the assessment of their possible cytotoxicity is a necessary step in the evaluation of their biocompatibility. The present study is carried out to evaluate the cytotoxicity of a new elastomeric sterile and radiopaque impression material. Human gingival fibroblasts, cultured in vitro are exposed directly to Elite Implant in three different viscosities, heavy, medium, and light. At 3, 9, 24, 48, and 72 h, the cellular proliferation is evaluated. In parallel, human gingival fibroblasts are exposed indirectly by means of fluid extracts of Elite Implant. The cellular viability is evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide, (MTT) assay (Sigma, St Louis, Mo). The gingival fibroblasts proliferation and viability are unaffected by the presence of Elite Implant. This new impression material may represent a safe medical device for clinical and surgical applications. In addition, this material is radiopaque and, thus, can be identified radiographically. PMID:17065163

  10. Plutonium air transportable package development using metallic filaments and composite materials

    A new design concept for plutonium air transport packagings has been developed by the Transportation Systems Department and modeled by the Engineering Mechanics and Material Modeling Department at Sandia National laboratories. The new concept resulted from an in-depth review of existing package design philosophies and limitations. This new design concept uses a very robust primary containment vessel with elastomeric seals for protection and confinement of an inner containment vessel with contents. An overpack consisting of multiple layers of plastically-deformable metallic wire mesh and high-tensile strength materials is placed around the containment vessels to provide energy absorption for the primary containment vessel as well as thermal protection. The use of intermittent layers with high-tensile strength results in a limiter which remains in place during accidental impact events and can be relied upon to provide subsequent puncture and fire protection. In addition, an outer shell around the energy absorbing material is provided for handling and weather protection. Scoping tests were performed on material samples, wall sections, and partially modeled prototypes. To evaluate various design features, finite element analyses were performed on the package

  11. Static seals and their application in water-cooled nuclear reactor systems

    Information relative to six types of static seals commonly used in the primary cooling systems of nuclear reactors is compiled. This information includes a description of each type of seal, its material of construction, design features, operating experience, and advantages and disadvantages. The types covered include spiral-wound asbestos-filled gaskets, hollow metallic O-rings, Belleville spring type of gasketed joints, integrated elastomer and metal retainer gaskets, and solid metal gaskets with heavy cross sections. Omega, canopy, and lip seals are discussed briefly, and information on flange design for gasketing is also presented

  12. The effect of material difference and flange nominal size on the sealing performance of new gasketless flanges

    This paper deals with a new seal system between flange joints without using a gasket. This gasketless flange includes a groove and an annular lip that is machined in one of the flange rings which when removed being in contact with the other flange to form a seal line when the flanges are assembled. In this study, firstly, fundamental dimensions are examined for unplasticized polyvinyl chloride (PVC-U JIS) to obtain the best sealing performance. Then, the effects of material difference and flange nominal size upon the sealing performance of the new gasketless flange are investigated for two types of materials, 0.25% carbon steel (S25C JIS) and PVC-U. It is found that the critical internal pressure at which leakage appears is mainly controlled by the maximum stress at the annular lip for each material even if the flange nominal sizes are different. The gasketless flange made by PVC-U shows the higher critical internal pressure compared with the case of S25C if the same clamping forces are applied. The effect of stress relaxation for PVC-U on the sealing performance is also considered. Then, it may be concluded that this PVC-U gasketless flange as well as S25C has good sealing performance

  13. Materials development

    Objective of the materials program is the development of a structural material for the MSBR primary circuit which is resistant to irradiation embrittlement and intergranular attack by fission products. The bulk of the work was done on the development and study of modified Hastelloy N (Ti, Nb), including its interaction with salt and fission Te. Materials (Ta-10 percent W, Mo, graphite) are also being tested for corrosion resistance at 600 and 7000C to Bi--Li for use in fuel processing

  14. Engineering materials

    Kumaraswamy, Mohan

    2002-01-01

    One element of the CIVCAL project Web-based resources containing images, tables, texts and associated data of the Engineering Materials such as concrete, metals and wood. Portland Cement Concrete is a particulate composite consisting of a continuous binder phase, the cementitious matrix and a dispersed particulate phase, the aggregates. Metals as construction material are an important construction material. They possess characteristics such as strength, stiffness, toughness and ductili...

  15. Material Systems

    Jensen, Mads Brath; Mortensen, Henrik Rubæk; Mullins, Michael;

    2009-01-01

    This paper describes and reflects upon the results of an investigative project which explores the setting up of a material system - a parametric and generative assembly consisting of and taking into consideration material properties, manufacturing constraints and geometric behavior. The project...... approaches the subject through the construction of a logic-driven system aiming to explore the possibilities of a material system that fulfills spatial, structural and performative requirements concurrently and how these are negotiated in situations where they might be conflicting....

  16. Materializing Ethnography

    Geismar, H.; Horst, H. A.

    2004-01-01

    The articles in this volume were originally presented in a panel entitled ‘Material Methodologies’ at the American Anthropological Association meeting in New Orleans (November 2002). The panel was devised to tie together theoretical advances in the study of the material with the creative possibilities of fieldwork practices. Through detailed ethnographic discussion, we highlighted the ways in which a focus on a specifically material world enabled us to discover new perspecti...

  17. Plutonium air transportable package development using metallic filaments and composite materials

    A new design concept for plutonium air transport packagings has been developed by the Transportation Systems Department and modeled by the Engineering Mechanics and Material Modelinc, Department at Sandia National Laboratories (SNL). The new concept resulted from an in-depth review (Allen et al., 1989) of existing, package design philosophies and limitations. This review indicated a need for a new package which could survive combinations of impact, fire, and puncture environments, and which could be scaled up or down to meet a wide range of requirements for various contents and regulations. This new design concept uses a very robust primary containment vessel with elastomeric seals for protection and confinement of an inner containment vessel with contents. An overpack consisting of multiple layers of plastically-deformable metallic wire mesh and high-tensile strength materials is placed around the containment vessels to provide energy absorption for the primary containment vessel as well as thermal protection. The use of intermittent layers with high-tensile strength results in a limiter which remains in place during accidental impact events and can be relied upon to provide subsequent puncture and fire protection. In addition, an outer shell around the energy absorbing material is provided for handling, and weather protection

  18. Materializing ideas

    Strandvad, Sara Malou

    2011-01-01

    Based on a qualitative study of development processes in the Danish film industry, this article sketches a socio-material perspective for analysing the production of culture. Whereas previous studies of cultural production have identified social factors in cultural production, this article sets out...... while it is becoming materialized....

  19. Scintillator material

    A scintillator material for detection and quantitative determination of ionizing radiation is discussed consisting of an acridone dissolved in a fluid or solid medium. Solvent mixtures with at least one protogenic component or polymers and copolymers are used. The scintillator material is distinguished by an excellent stability at high energy doses

  20. Composite material

    Hutchens, Stacy A. (Knoxville, TN); Woodward, Jonathan (Solihull, GB); Evans, Barbara R. (Oak Ridge, TN); O' Neill, Hugh M. (Knoxville, TN)

    2012-02-07

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  1. Composite material

    Hutchens, Stacy A.; Woodward, Jonathan; Evans, Barbara R.; O'Neill, Hugh M.

    2012-02-07

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  2. Evaluation of seals for mechanical penetrations of containment buildings

    This report describes tests of elastomeric seals that are used in the mechanical penetrations of nuclear power plant containments. These tests assessed the effects of thermal aging, radiation and thermal aging, sealing surface separation, and squeeze on the performance of several gasket designs: O-ring, gum drop, double dog ear, and tongue and groove. Both ethylene propylene rubber and silicone rubber gaskets were tested. The environment for testing enveloped a hypothetical severe seals is quantified in terms of the leakage onset point on the time-temperature curve

  3. Elastomeric composites for flexible microwave substrates

    Awang, Robiatun A.; Baum, Thomas; Berean, Kyle J.; Yi, Pyshar; Kalantar-zadeh, Kourosh; Sriram, Sharath; Rowe, Wayne S. T.

    2016-03-01

    Manipulating dielectric properties of polydimethylsiloxane (PDMS) is an important consideration for flexible, low-loss device design. This paper presents a method for reducing dielectric loss (tan δ) by forming PDMS composites loaded with various concentrations of either alumina (Al2O3) or polytetrafluoroethylene (PTFE) particles. The structural, mechanical, and electrical properties of the composites are investigated. Theoretical mixing models were used to predict the relative permittivity (ɛr) of PDMS composites, and good similarity with the measured ɛr was observed. The incorporation of either low dielectric loss filler in the PDMS matrix (up to 50 wt. % filler loading) is shown to reduce the dielectric loss while maintaining the flexibility of the host matrix. The fillers can also control the permittivity of the composite, either increasing or decreasing relative permittivity from that of PDMS. Interestingly, a strain of ˜500% can be applied to 15 wt. % PDMS/PTFE composites, compared with ˜350% for pure PDMS.

  4. 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 obesity1. Currently, bypass surgery using autologous vessels, allografts, and synthetic grafts are known as a commonly used for arterial substitutes2. 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 ...

  5. 薄片状聚酰亚胺多孔材料的研究进展%Research Progress of Thin Sheet Polyimide Porous Materials

    马晶晶; 詹茂盛; 王凯; 刘小艳; 吴畏

    2013-01-01

    综述了薄片状聚酰亚胺多孔材料的研究进展,主要介绍了薄片状的聚酰亚胺多孔材料的产品种类、研究单位、性能指标、应用情况及制备方法,并提出了目前对薄片状聚酰亚胺多孔材料研究存在的问题以及研究现状,展望了薄片状聚酰亚胺多孔材料在今后的研究方向和发展趋势.薄片状聚酰亚胺多孔材料,已经作为垫片用在宇宙飞船的多层隔热系统中,甚至会逐渐替代传统的多层隔热系统材料.%The recent development of the thin sheet polyimide porous material is reviewed. The product types, properties and application of the thin sheet polyimideporous material are introduced and its future research direction as well as the development trends is also pointed out. The thin sheet polyimide porous materials will gradually replace traditional MLI materials as a gasket in the multi-layer insulation system of spacecraft.

  6. Thermoluminescent materials

    Thermoluminescence is the emission of light from substances when they are heated. This phenomena is observed for many synthetic and natural substances. These thermoluminescent materials must be ionic crystals, covalent crystals, and molecular crystals - an insulator or a semiconductor, but metals do not exhibit luminescent properties because they could not storage radiation energy. Most research has been devoted to the discovery and development of materials suitable for thermoluminescence dosemeters, and some phosphors are used routinely in dosimetric applications. But for other purposes, many interesting materials have been suggested and investigated. (author)

  7. Polymer Materials

    Charles C. Han; DONG Jinyong; NIU Hui; CHENG He; HUANG Ye; ZHENG Jianfen; XU Shanshan

    2011-01-01

    @@ Since the second half of the 20th century, polymer materials have already become an essential part of our daily life.The use of polymeric materials has already exceeded that of metals and ceramics in terms of volume and is intimately connected to our clothing, food, household use, transportation, and medical needs.Meanwhile it also brought some recycle and environmental problems.In the 21 st century, human beings are facing ever increasing challenges on environmental protection, energy shortage, and health-medical problems, which have made even higher demand on polymer materials due to its light weight, flexibility and high functionality.

  8. Utopian Materialities

    Elgaard-Jensen, Torben

    2004-01-01

    In various ways, this paper makes the counter-intuitive claim that the utopian and the material are thoroughlyinterdependent, rather than worlds apart. First, through a reading of Thomas More's Utopia, it is argued thatUtopia is the product of particular kinds of relations, rather than merely a...... detachment from the known world.Second, the utopianism of a new economy firm is examined. It is argued that the physical set-up of the firm -in particular the distribution of tables and chairs - evoke a number of alternatives to ordinary work practice.In this way the materialities of the firm are crucial to...... its persuasive image of being the office of the future.The notion that utopia is achieved through material arrangements is finally related to the analysis of facts andfictions in ANT. It is argued, that even though Utopias are neither fact nor fiction, they are both material andeffective on the...

  9. Encountering Materiality

    Svabo, Connie

    2016-01-01

    DHT researcher Connie Svabo and artist Charlotte Grum did a joint performance presentation titled Becoming Sheep, Becoming Animal at the international conference Encountering Materiality – Transdisciplinary Conversations, held in Geneve, Schwitzerland, June 23-25 2016.......DHT researcher Connie Svabo and artist Charlotte Grum did a joint performance presentation titled Becoming Sheep, Becoming Animal at the international conference Encountering Materiality – Transdisciplinary Conversations, held in Geneve, Schwitzerland, June 23-25 2016....

  10. Background Material

    Zandersen, Marianne; Hyytiäinen, Kari; Saraiva, Sofia;

    2016-01-01

    This document serves as a background material to the BONUS Pilot Scenario Workshop, which aims to develop harmonised regional storylines of socio-ecological futures in the Baltic Sea region in a collaborative effort together with other BONUS projects and stakeholders.......This document serves as a background material to the BONUS Pilot Scenario Workshop, which aims to develop harmonised regional storylines of socio-ecological futures in the Baltic Sea region in a collaborative effort together with other BONUS projects and stakeholders....

  11. Video material

    Mark Miodownik

    2004-01-01

    The scanning electron microscopy (SEM) images of microelectromechanical systems in motion pictures were discussed. Computer-generated special effects were used on materials like silicon, polyurethanes and wood for giving special effects in the movies. It was found that the use of digital video was bringing science and entertainment industry closer to form a new fusion of art and science. It was suggested that more sophisticated models of materials behavior were required to render realistic ef...

  12. Propulsion materials

    Wall, Edward J. [U.S. Dept. of Energy, Washington, D.C. (United States); Sullivan, Rogelio A. [U.S. Dept. of Energy, Washington, D.C. (United States); Gibbs, Jerry L. [U.S. Dept. of Energy, Washington, D.C. (United States)

    2008-01-01

    The Department of Energy’s (DOE’s) Office of Vehicle Technologies (OVT) is pleased to introduce the FY 2007 Annual Progress Report for the Propulsion Materials Research and Development Program. Together with DOE national laboratories and in partnership with private industry and universities across the United States, the program continues to engage in research and development (R&D) that provides enabling materials technology for fuel-efficient and environmentally friendly commercial and passenger vehicles.

  13. Photostrictive materials

    Kundys, B.

    2015-01-01

    Light-matter interactions that lead to nonthermal changes in size of the sample constitute a photostrictive effect in many compounds. The photostriction phenomenon was observed in four main groups of materials, ferroelectrics, polar, and non-polar semiconductors, as well as in organic-based materials that are reviewed here. The key mechanisms of photostriction and its dependence on several parameters and perturbations are assessed. The major literature of the photostriction is surveyed, and t...

  14. Magnetostrictive materials

    The paper has been prepared on the basis of literature survey covering last 10 years. The article contains concise overview of the effect of magnetostriction and related effects such as Villarie effect, Young modulus change effect, Widemann and Birkhausen effects. Magnetostrictive materials (MM) covert reversibly magnetic energy into energy of elastic deformation. Traditional, as well as newest magnetostrictive materials, exhibiting effect of giant magnetostriction, e.g. containing rare earth metals (Tb,Dy) Terphenol-D, have been discussed. Interesting new groups of materials appear to be hybrid systems, which combine properties of magnetostrictive and magnetic shape memory materials. Processing methods of MM comprise rapid solidification of liquid alloy, monocrystallization, directional crystallization and powder metallurgy. Potential application areas of MM are generally related to their use as sensors and actuators. MM find applications in sonar devices, seismic sensors, geological tomography, hydraulic valves, sensors of motion, force and magnetic field, and many others. Interesting field of MM applications is related to systems for health monitoring of composite materials. Directions for further research in the field of MM should consider development of new materials having lower anisotropy and hysteresis, and development of a new technologies e.g. thin magnetostrictive films. (author)

  15. BOOK REVIEW: NMR Imaging of Materials

    Blümich, Bernhard

    2003-09-01

    spectroscopic methods to weight or filter the spin signals represents the core of the book. This is a subject where Blümich is deeply involved with substantial contributions. The chapter includes a lot of ideas to provide MR contrast between different regions based on their mobility, diffusion, spin couplings or NMR spectra. After describing NMR imaging methods for solids with broad lines, Blümich spends time on applications in the last two chapters of the book. This part is really fun to read. It underlines the effort to bring NMR into many kinds of manufacturing. Car tyres and high-voltage cables are just two such areas. Elastomeric materials, green-state ceramics and food science represent other interesting fields of applications. This part of the book represents a personal but nevertheless extensive compilation of modern applications. As a matter of course the MOUSE is presented, a portable permanent-magnet based NMR developed by Blümich and his co-workers. Thus the book is not only of interest to NMR spectroscopists but also to people in material science and chemical engineering. The bibliography and indexing are excellent and may serve as an attractive reference source for NMR spectroscopists. The book is the first on the subject and likely to become the standard text for NMR imaging of materials as the books by Abragam, Slicher and Ernst et al are for NMR spectroscopy. The purchase of this beautiful book for people dealing with NMR spectroscopy or medical MRI is highly recommended. Ralf Ludwig

  16. Analytical Model of Elastomeric Lag Damper Kinematic Coupling and Its Effect on Helicopter Air Resonance in Hover%粘弹减摆器几何耦合模型及对直升机悬停空中共振的影响.

    胡国才; 向锦武; 张晓谷

    2002-01-01

    For an elastomeric lag damper with nonlinear properties and kinematic couplings, its differential equation about equilibrium position was derived in a rotating frame. The equation was then transformed into a non-rotating frame by multi-blade transformation and incorporated into the rotor/airframe differential equations for eigen analysis. The effects of damper steady displacement and kinematic couplings on helicopter air resonance in hover were analyzed. The results demonstrate that the elastomeric damper can increase helicopter dynamic stability; however, its available damping will decrease as its steady displacement increased. For the notional rotor system, the damper steady displacement will decrease when kinematic couplings are introduced, and hence the regressive lag modal damping can be increased.%针对具有几何耦合的非线性粘弹减摆器,在旋转坐标系下建立了其在平衡位置附近的小扰动微分方程,然后通过多桨叶坐标转换的方法将方程变换到不转坐标系中,并与直升机悬停时的线化小扰动方程结合起来进行特征值分析;减摆器静态位移和几何耦合对直升机空中共振稳定性的影响进行了分析.结果表明,粘弹减摆器会提高直升机空中共振稳定性;增大减摆器的静态位移会降低其有效阻尼;对于所考虑的旋翼系统来说,几何耦合可能会减小减摆器的静态位移,从而提高摆振后通型模态的阻尼.

  17. Innovative lightweight materials for motor cars. Status, trends, potential; Innovative Leichtbauwerkstoffe im Automobilbau. Status, Trends, Potentiale

    Hoffmann, E.; Euler, W.; Baumgart, D.; Deinzer, G. [Opel (A.) AG., Ruesselsheim (Germany). Internationales Technisches Entwicklungszentrum

    1999-07-01

    The modern motor car industry is undergoing a period of transition marked by changes in technologies, logistics, production processes, and the nature of work. Parallel to this, there are changes on the materials sector, which are characterized by materials substitutions in components, functional groups and systems. During the last decade, the metal fraction in motor cars was reduced by 4 % in favour of plastics and elastomers. This may seem a moderate change, but it amounts to quite a tonnage when scaled up to, e.g., a series of 500,000 vehicles, and it becomes clear that the substitutions also affect the national economy as a whole. [German] Die heutige Automobiltechnik und die auf diesem Sektor taetige Industrie erleben z.Zt. national und international eine Phase tiefgreifender Strukturaenderungen und weitreichender Wandlungen bei den eingesetzten Technologien, bei der Logistik, den Fertigungsablaeufen sowie den Arbeitsinhalten. Ueberlagert werden diese technologisch-oekonomischen Veraenderungen von Verschiebungen auf dem Materialsektor, wo bei Komponenten, Baugruppe und Systemen Werkstoffsubstitutionen erfolgen. Fuer den Sektor metallischer Werkstoffe ergibt sich ueber einen Zeitraum von 10 Jahren eine Reduzierung des prozentualen Anteils am Fahrzeuggesamtgewicht um 4 Punkte, waehrend die Kunststoffe und Elastomere in diesem Zeitraum in Summe um etwa den gleichen Anteil zunehmen. In Gewichtsanteilen pro Fahrzeug erscheinen diese Zahlen noch recht moderat, bezogen auf eine Serie von 500.000 Fahrzeugen ergeben sich - auch schon fuer einen Hersteller - recht beeindruckende Tonnagen, bezogen auf eine nationale Produktion sind die Aenderungen durch Substitution relevant fuer eine Volkswirtschaft. (orig./AKF)

  18. Design improvements for gloveboxes used [in] 238PuO2 process operations

    238PuO2 process operations are housed in a complex of 76 gloveboxes and introductory hoods connected by means of an overhead trolley housed in a tunnel. Because a significant number of the gloveboxes used for 238PuO2 processing were installed before the original startup of the facility in 1978, they have been in service for nearly 20 years. During a recent heat source production campaign, numerous contamination releases in the 238PuO2 processing area were traced to degraded elastomer gaskets used for glovebox connections, and attachment of feed-throughs, service panels, and windows. Evaluation of the degraded gaskets revealed that a combination of radiolytic degradation related to the high specific activity of 238Pu, and extended service at high altitude in a low (to extremely low) humidity environment had resulted in accelerated gasket aging. However, it was also apparent that gasket design was the most important factor in actual contamination release. All of the contamination releases that were traced to degraded gaskets occurred in variations of a design that used a spline to expand an elastomeric gasket into the space between a connecting flange, window, or service panel, and a glovebox opening. No contamination releases were traced to the gasket design that employed bolted clamps to compress the gasket between a connecting flange, window, or panel, and the exterior surface of a glovebox opening. As a result of these findings, the Actinide Ceramics group at LANL (NMT-9) has initiated a routine replacement and upgrade program to replace aging gloveboxes. All of the new gloveboxes will utilize the preferred gasket design, which is expected to reduce the number and frequency of contamination releases

  19. Design improvements for gloveboxes used [in] {sup 238}PuO{sub 2} process operations

    George, T.G. [Los Alamos National Lab., NM (United States). Nuclear Materials Technology Div.

    1997-09-01

    {sup 238}PuO{sub 2} process operations are housed in a complex of 76 gloveboxes and introductory hoods connected by means of an overhead trolley housed in a tunnel. Because a significant number of the gloveboxes used for {sup 238}PuO{sub 2} processing were installed before the original startup of the facility in 1978, they have been in service for nearly 20 years. During a recent heat source production campaign, numerous contamination releases in the {sup 238}PuO{sub 2} processing area were traced to degraded elastomer gaskets used for glovebox connections, and attachment of feed-throughs, service panels, and windows. Evaluation of the degraded gaskets revealed that a combination of radiolytic degradation related to the high specific activity of {sup 238}Pu, and extended service at high altitude in a low (to extremely low) humidity environment had resulted in accelerated gasket aging. However, it was also apparent that gasket design was the most important factor in actual contamination release. All of the contamination releases that were traced to degraded gaskets occurred in variations of a design that used a spline to expand an elastomeric gasket into the space between a connecting flange, window, or service panel, and a glovebox opening. No contamination releases were traced to the gasket design that employed bolted clamps to compress the gasket between a connecting flange, window, or panel, and the exterior surface of a glovebox opening. As a result of these findings, the Actinide Ceramics group at LANL (NMT-9) has initiated a routine replacement and upgrade program to replace aging gloveboxes. All of the new gloveboxes will utilize the preferred gasket design, which is expected to reduce the number and frequency of contamination releases.

  20. Shielding material

    The present invention effectively utilizes iron reinforced concrete wastes generated upon dismantling of concretes of nuclear facilities, to provide shielding material. That is, at least one of members selected from the group consisting of iron rods in iron-reinforced concretes and, regenerated aggregates regenerated from concrete wastes upon dismantling is charged in a predetermined mold. Cement pastes or cement mortars are charged therein, and solidified, cured and released from the mold. With such procedures, a block-formed shielding materials made of precast concretes can be obtained. In this case, the cements including much water of crystallization are used. Since iron reinforcing dusts and iron reinforcing dust chips are contained in the shielding materials, a great γ-ray shielding effect can be obtained. Further, since cements containing a great amount of water of crystallization are used, a great neutron shielding effect can be obtained. (I.S.)

  1. Virtual materiality

    Søndergaard, Dorte Marie

    There are two questions that feed the curiosity of this paper: a theoretical question connected to the conceptualization of materiality across the real/virtual divide and an empirical question connected to the understanding of virtual experiences in children’s lives when studied in relation to...... recounts of them and 3. the consumption of other media products like movies, reality shows, YouTube videos etc. How do we theorize ‘matter’ in such dimensions? Is it possible to theorize virtual matter as ‘materiality’ in line with any real life materiality? What conceptualization will help us understand...... is a field that begs for new theorizing and new analytical tools. (Søndergaard 2008, 2009a) It is a field that deals with children’s individual and collective processes of becoming, of materializing and of entering in and as agentic part(ner)s of the human and non-human world. But current theoretical...

  2. Layered materials

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and

  3. Photovaltic materials

    Bube, R H

    1998-01-01

    Research and development of photovoltaic solar cells is playing an ever larger practical role in energy supply and ecological conservation all over the world. Many materials science problems are encountered in understanding existing solar cells and the development of more efficient, less costly, and more stable cells. This important and timely book provides a historical overview, but concentrates primarily on exciting developments in the last decade. It describes the properties of the materials that play an important role in photovoltaic applications, the solar cell structures in which they ar

  4. Electronic materials

    Kwok, H L

    2010-01-01

    The electronic properties of solids have become of increasing importance in the age of information technology. The study of solids and materials, while having originated from the disciplines of physics and chemistry, has evolved independently over the past few decades. The classical treatment of solid-state physics, which emphasized classifications, theories and fundamental physical principles, is no longer able to bridge the gap between materials advances and applications. In particular, the more recent developments in device physics and technology have not necessarily been driven by new conc

  5. Touching Materiality

    Rasmussen, Lisa Rosén

    2012-01-01

    Dripping ink pens, colourful paint on skin, vegetables pots on a school roof. In interviews with three generations of former school pupils, memories of material objects bore a relation to everyday school life in the past. Interwoven, these objects entered the memorising processes, taking the inte...

  6. Emerging Materiality

    Bertelsen, Olav Wedege; Breinbjerg, Morten; Pold, Søren

    2009-01-01

    The authors examine how materiality emerges from complex chains of mediation in creative software use. The primarily theoretical argument is inspired and illustrated by interviews with two composers of electronic music. The authors argue that computer mediated activity should not primarily be...

  7. Nuclear materials

    In 1996, 39 inspections of nuclear materials were performed, 22 of them performed in co-operation with IAEA inspectors. The main content of common inspections with IAEA was the inspection of both fresh and spent fuel in Bohunice NPPs and Mochovce NPPs. During 1996 there were 420 spent fuel assemblies transported from the V-1 and V-2 NPPs units to the interim spent fuel storage and 396 spent fuel assemblies were transported to the Dukovany NPP. Current state of stored spent fuel in the interim spent fuel storage is 4656 fuel assemblies, 4050 of them are Bohunice NPPs assemblies and 606 of them are fuel assemblies which belong to Dukovany NPP. There are 128 spent fuel assemblies stored in A-1 NPP, which are placed in cases of the long-term storage. Inspections of fresh fuel storage in the V-1, V-2 and Mochovce NPPs were performed, as well as spent fuel inspections in the A-1 NPP and in the interim spent fuel storage in Bohunice. From the outcomes of inspections resulted, that the limits and conditions, operating procedures and conditions of nuclear safety were not violated in any ease. There was no extraordinary event at above mentioned equipment during the 1996 and the equipment was reliably operated. NRA SR performed during 1996 eight inspections focused on safety protection of nuclear equipment and nuclear materials, and no significant deficiencies, which could resulted in extraordinary events or violation of nuclear safety were found out. Safety of transportation of fresh fuel, spent fuels, and other materials is discussed. NRA SR performed inspection focused on checking transportation readiness each transportation of the spent nuclear fuel. Serious deficiencies were not found out. Suggested system for treatment of radioactive materials caught at illegal trade is described. An attempt to export 3 radioactive sources in consignment of iron scrap to Italy came about in 1996. The NRA SR continued in co-operation with IAEA on updating IAEA database to illegal

  8. Friction Material Composites Materials Perspective

    Sundarkrishnaa, K L

    2012-01-01

    Friction Material Composites is the first of the five volumes which strongly educates and updates engineers and other professionals in braking industries, research and test labs. It explains besides the formulation of design processes and its complete manufacturing input. This book gives an idea of mechanisms of friction and how to control them by designing .The book is  useful for designers  of automotive, rail and aero industries for designing the brake systems effectively with the integration of friction material composite design which is critical. It clearly  emphasizes the driving  safety and how serious designers should  select the design input. The significance of friction material component like brake pad or a liner as an integral part of the brake system of vehicles is explained. AFM pictures at nanolevel illustrate broadly the explanations given.

  9. Materials Science

    2003-01-01

    The Materials Science Program is structured so that NASA s headquarters is responsible for the program content and selection, through the Enterprise Scientist, and MSFC provides for implementation of ground and flight programs with a Discipline Scientist and Discipline Manager. The Discipline Working Group of eminent scientists from outside of NASA acts in an advisory capacity and writes the Discipline Document from which the NRA content is derived. The program is reviewed approximately every three years by groups such as the Committee on Microgravity Research, the National Materials Advisory Board, and the OBPR Maximization and Prioritization (ReMaP) Task Force. The flight program has had as many as twenty-six principal investigators (PIs) in flight or flight definition stage, with the numbers of PIs in the future dependent on the results of the ReMaP Task Force and internal reviews. Each project has a NASA-appointed Project Scientist, considered a half-time job, who assists the PI in understanding and preparing for internal reviews such as the Science Concept Review and Requirements Definition Review. The Project Scientist also insures that the PI gets the maximum science support from MSFC, represents the PI to the MSFC community, and collaborates with the Project Manager to insure the project is well-supported and remains vital. Currently available flight equipment includes the Materials Science Research Rack (MSRR-1) and Microgravity Science Glovebox. Ground based projects fall into one or more of several categories. Intellectual Underpinning of Flight Program projects include theoretical studies backed by modeling and computer simulations; bring to maturity new research, often by young researchers, and may include preliminary short duration low gravity experiments in the KC-135 aircraft or drop tube; enable characterization of data sets from previous flights; and provide thermophysical property determinations to aid PIs. Radiation Shielding and preliminary In

  10. Magnetocaloric materials

    Jeppesen, Stinus

    2008-10-15

    New and improved magnetocaloric materials are one of the cornerstones in the development of room temperature magnetic refrigeration. Magnetic refrigeration has been used since the 1930ies in cryogenic applications, but has since the discovery of room temperature refrigerants received enormous attention. This Ph.D. work has been mainly concerned with developing a new technique to characterize the magnetocaloric effect (MCE) and using this technique in the investigations on new and improved magnetocaloric materials. For this purpose a novel differential scanning calorimeter (DSC) with applied magnetic fields was developed for measuring heat capacity as function of magnetic field. Measurements using the developed DSC demonstrate a very high sensitivity, fast measurements and good agreement with results obtained by other techniques. Furthermore, two material systems have been described in this work. Both systems take basis in the mixed-valence manganite system La{sub 1-x}Ca{sub x}MnO{sub 3} well known from research on colossal magnetoresistance (CMR). The mixed-valence manganite crystallizes in the perovskite structure of general formula ABO{sub 3}. The first material system is designed to investigate the influence of low level Cu doping on the B-site. Six different samples were prepared with over-stoichiometric compositions La{sub 0.67}Ca{sub 0.33}Mn{sub 1.05}Cu{sub x}O{sub 3}, x=0, 1, 2, 3, 4 and 5%. All compositions crystallized well in the same perovskite structure, but the morphology of the samples changed drastically with doping. Investigation on the magnetocaloric properties revealed that small levels of Cu up to around 3% could improve the magnetocaloric performance of the materials. Furthermore, Cu could be used to tune the temperature interval without deteriorating the MCE, which is a much desired characteristic for potential use in magnetic refrigerators. A less comprehensive part of the work has been concerned with the investigation of doping on the A

  11. Classy material

    Mark Miodownik

    2005-01-01

    The usefulness of glass and it's impact on our culture is discussed. Glass is irreplaceable as our main transparent protection against the wind, rain, heat, and cold, and is therefore, the key to our trains, plains, automobiles, and buildings. The transparency and inertness of glass pushed chemistry forward by allowing color changes of chemical reactions to be measured and gas evolution to be observed, so that glass became the essential material for chemistry. Glass is used by the physicists ...

  12. Prosthesis Material

    2004-01-01

    In this photograph, Amputee Amie Bradly uses a NASA-developed prosthesis to paint her fingernails. Derived from foam insulation technology used to protect the Space Shuttle External Tank from excessive heat, FAB/CAD, a subsidiary of the Harshberger Prosthetic and Orthotic Center, utilized the technology to replace the heavy, fragile plaster they used to produce master molds for prosthetics. The new material was lighter, cheaper and easier to manufacture than plaster, resulting in lower costs to the customer.

  13. Material monitoring

    Waste Reduction Operations Complex (WROC) facilities are located at the Idaho National Engineering Laboratory (INEL). The overall goal for the Pollution Prevention/Waste Minimization Unit is to identify and establish the correct amount of waste generated so that it can be reduced. Quarterly, the INEL Pollution Prevention (P2) Unit compares the projected amount of waste generated per process with the actual amount generated. Examples of waste streams that would be addresses for our facility would include be are not limited to: Maintenance, Upgrades, Office and Scrap Metal. There are three potential sources of this variance: inaccurate identification of those who generate the waste; inaccurate identification of the process that generates the waste; and inaccurate measurement of the actual amount generated. The Materials Monitoring Program was proposed to identify the sources of variance and reduce the variance to an acceptable level. Prior to the implementation of the Material Monitoring Program, all information that was gathered and recorded was done so through an informal estimation of waste generated by various personnel concerned with each processes. Due to the inaccuracy of the prior information gathering system, the Material Monitoring Program was established. The heart of this program consists of two main parts. In the first part potential waste generators provide information on projected waste generation process. In the second part, Maintenance, Office, Scrap Metal and Facility Upgrade wastes from given processes is disposed within the appropriate bin dedicated to that process. The Material Monitoring Program allows for the more accurate gathering of information on the various waste types that are being generated quarterly

  14. Biomedical Materials

    CHANG Jiang; ZHOU Yanling

    2011-01-01

    @@ Biomedical materials, biomaterials for short, is regarded as "any substance or combination of substances, synthetic or natural in origin, which can be used for any period of time, as a whole or as part of a system which treats, augments, or replaces any tissue, organ or function of the body" (Vonrecum & Laberge, 1995).Biomaterials can save lives, relieve suffering and enhance the quality of life for human being.

  15. Radiation Balance of Urban Materials and Their Thermal Impact in Semi-Desert Region: Mexicali, México Study Case

    Néstor Santillán-Soto

    2015-10-01

    Full Text Available Net radiation is an essential forcing of climate in the lower layers of Earth’s atmosphere. In this paper, radiation balance is measured in clay soil and green grass, and is compared with three urban materials. These materials: asphalt, concrete and white painted elastomeric polystyrene roofing sheet are widely used in Mexicali, Baja California, México. This study was carried out during August of 2011, the hottest time of the year. The 24-hour average values of net radiation found were: 137.2 W·m−2 for asphalt, 119.1 for concrete, 104.6 for clay soil, 152 for green grass and 29.2 for the polystyrene insulation. The latter two types of materials are likely to be the most effective in reducing urban heat island effects. This variation in the radiation balance has widespread implications for human living conditions, as land cover change tends to be towards surfaces that have higher levels of net radiation.

  16. Migration of epoxidised soya bean oil into foods from retail packaging materials and from plasticised PVC film used in the home.

    Castle, L; Mayo, A; Gilbert, J

    1990-01-01

    Epoxidised soya bean oil (ESBO) is used as a plasticiser and heat stabiliser in a number of feed contact materials, in particular in poly(vinyl chloride) (PVC) films and gaskets. The level of ESBO migration into foods has been determined using a combined gas chromatographic/mass spectrometric (GC/MS) analytical procedure. The study has included both the use of ESBO-containing materials for retail packaged foods and the domestic use of plasticised PVC films for applications such as wrapping food and covering food for re-heating in a microwave oven. Levels of ESBO in fresh retail meat samples wrapped in film ranged from less than 1 to 4 mg/kg, but were higher (max. 22 mg/kg) in retail cooked meat. Migration into sandwiches and rolls from 'take-away' outlets ranged from less than 1 to 27 mg/kg depending on factors such as the type of filling and the length of the contact time prior to analysis. The levels of migration of ESBO into cheese and cakes were consistent with previous experience with plasticiser migration--direct contact with fatty surfaces leading to the highest levels. When the film was used for microwave cooking in direct contact with food, levels of ESBO from 5 to 85 mg/kg were observed, whereas when the film was employed only as a splash cover for re-heating foods, ESBO levels ranged from 0.1 to 16 mg/kg. For a variety of baby foods there was no significant difference in ESBO levels between foods packaged in glass jars with PVC gaskets and foods in cans containing ESBO in the can lacquer. In both cases ESBO levels were low, ranging from less than 0.1 to 7.6 mg/kg. It is not clear for these retail samples, if the low levels observed (average 1.9 mg/kg) result solely from migration or contain some contribution from naturally occurring epoxides. PMID:2307263

  17. Plugging material

    Kuznetsov, Yu.S.; Kravtsov, V.M.; Mavlyutov, M.R.; Spivak, A.I.; Trutnev, G.A.

    1982-01-01

    Plugging material is proposed which includes Portland cement and quartz sand. In order to improve the strength of the stone and sedimentation stability of the cement mud and to guarantee expansion during hardening of the stone in the interval 20-180/sup 0/C, it also contains solid residue of wastes from soda production thermally treated at temperature 850-900/sup 0/C with the following ratio of components (% by mass): Portland cement 60-80, quartz sand 15-20; solid residue of soda production 5-20.

  18. Energy materials

    Bruce, Duncan W; Walton, Richard I

    2011-01-01

    In an age of global industrialisation and population growth, the area of energy is one that is very much in the public consciousness. Fundamental scientific research is recognised as being crucial to delivering solutions to these issues, particularly to yield novel means of providing efficient, ideally recyclable, ways of converting, transporting and delivering energy. This volume considers a selection of the state-of-the-art materials that are being designed to meet some of the energy challenges we face today. Topics are carefully chosen that show how the skill of the synthetic chemist can

  19. Advanced materials for control of post-earthquake damage in bridges

    This paper presents analytical modeling to study the seismic response of bridge systems with conventional and advanced details. For validation, a 33 m quarter-scale model of a four-span bridge incorporating innovative materials and details seismically tested on the shake tables at the University of Nevada, Reno was taken. The bridge specimen involved use of advanced materials and details to reduce damage at plastic hinges and minimize residual displacements. A three-dimensional, nonlinear model incorporating the response of the innovative materials was developed to study the bridge response using the finite-element software OpenSees. Existing finite-element formulations were used to capture the response of the advanced materials used in the bridge. The analytical model was found to be able to reproduce comparable bent displacements and bent shear forces within reasonable accuracy. The validated model was further used to study different types of bridges under suite of scaled bi-directional near-fault ground motions. Comparisons were made on behavior of five different bridge types, first conventional reinforced concrete bridge, second post-tensioned column bridge, third bridge with elastomeric rubber elements at the plastic hinge zone, fourth bridge with nickel–titanium superelastic shape memory alloy (SMA) reinforcing bar and fifth bridge with CuAlMn superelastic SMA reinforcing bar. Both the SMA used bridges also utilized engineered cementitious composite element at the plastic hinge zone. The results showed effectiveness of the innovative interventions on the bridges in providing excellent recentering capabilities with minimal damage to the columns. (paper)

  20. Photovoltaic Materials

    Duty, C.; Angelini, J.; Armstrong, B.; Bennett, C.; Evans, B.; Jellison, G. E.; Joshi, P.; List, F.; Paranthaman, P.; Parish, C.; Wereszczak, A.

    2012-10-15

    The goal of the current project was to help make the US solar industry a world leader in the manufacture of thin film photovoltaics. The overall approach was to leverage ORNL’s unique characterization and processing technologies to gain a better understanding of the fundamental challenges for solar cell processing and apply that knowledge to targeted projects with industry members. ORNL has the capabilities in place and the expertise required to understand how basic material properties including defects, impurities, and grain boundaries affect the solar cell performance. ORNL also has unique processing capabilities to optimize the manufacturing process for fabrication of high efficiency and low cost solar cells. ORNL recently established the Center for Advanced Thin-film Systems (CATS), which contains a suite of optical and electrical characterization equipment specifically focused on solar cell research. Under this project, ORNL made these facilities available to industrial partners who were interested in pursuing collaborative research toward the improvement of their product or manufacturing process. Four specific projects were pursued with industrial partners: Global Solar Energy is a solar industry leader in full scale production manufacturing highly-efficient Copper Indium Gallium diSelenide (CIGS) thin film solar material, cells and products. ORNL worked with GSE to develop a scalable, non-vacuum, solution technique to deposit amorphous or nanocrystalline conducting barrier layers on untextured stainless steel substrates for fabricating high efficiency flexible CIGS PV. Ferro Corporation’s Electronic, Color and Glass Materials (“ECGM”) business unit is currently the world’s largest supplier of metallic contact materials in the crystalline solar cell marketplace. Ferro’s ECGM business unit has been the world's leading supplier of thick film metal pastes to the crystalline silicon PV industry for more than 30 years, and has had operational

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

    Manoj Choudhary; Manpreet Kaur

    2015-01-01

    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 ...

  2. PREFACE: Superconducting materials Superconducting materials

    Charfi Kaddour, Samia; Singleton, John; Haddad, Sonia

    2011-11-01

    The discovery of superconductivity in 1911 was a great milestone in condensed matter physics. This discovery has resulted in an enormous amount of research activity. Collaboration among chemists and physicists, as well as experimentalists and theoreticians has given rise to very rich physics with significant potential applications ranging from electric power transmission to quantum information. Several superconducting materials have been synthesized. Crucial progress was made in 1987 with the discovery of high temperature superconductivity in copper-based compounds (cuprates) which have revealed new fascinating properties. Innovative theoretical tools have been developed to understand the striking features of cuprates which have remained for three decades the 'blue-eyed boy' for researchers in superconductor physics. The history of superconducting materials has been notably marked by the discovery of other compounds, particularly organic superconductors which despite their low critical temperature continue to attract great interest regarding their exotic properties. Last but not least, the recent observation of superconductivity in iron-based materials (pnictides) has renewed hope in reaching room temperature superconductivity. However, despite intense worldwide studies, several features related to this phenomenon remain unveiled. One of the fundamental key questions is the mechanism by which superconductivity takes place. Superconductors continue to hide their 'secret garden'. The new trends in the physics of superconductivity have been one of the two basic topics of the International Conference on Conducting Materials (ICoCoM2010) held in Sousse,Tunisia on 3-7 November 2010 and organized by the Tunisian Physical Society. The conference was a nice opportunity to bring together participants from multidisciplinary domains in the physics of superconductivity. This special section contains papers submitted by participants who gave an oral contribution at ICoCoM2010

  3. Propriedades reométricas e mecânicas e morfologia de compósitos desenvolvidos com resíduos elastoméricos vulcanizados Cure characteristics, mechanical properties and morphology of composites developed with addition of elastomeric vulcanized ground scraps

    Aline Zanchet

    2007-03-01

    Full Text Available Uma alternativa para as empresas geradoras de resíduos elastoméricos é a incorporação dos mesmos em suas formulações. Esse trabalho tem como objetivo preparar compósitos a partir da incorporação de resíduos industriais de SBR (copolímero de butadieno-estireno e de EPDM (terpolímero de etileno-propileno-dieno, em formulação ASTM específica para cada tipo de elastômero. Foram avaliadas as propriedades reométricas, mecânicas e morfológicas dos compósitos desenvolvidos. A incorporação do resíduo permitiu a obtenção de produtos que vulcanizam em menores tempos quando comparados a composições sem resíduo. A quantidade de resíduo, para o melhor resultado de resistência à tração foi de 37 e de 196 phr para os compósitos com SBR e EPDM, respectivamente. As micrografias de MEV corroboraram os resultados mecânicos dessas composições, indicando melhor homogeneidade do resíduo na respectiva matriz elastomérica.One alternative for elastomeric scraps generation is its incorporation in conventional formulations in the industry itself. In this work, compositions with incorporation of SBR (styrene butadiene rubber and EPDM (ethylene propylene diene rubber industrial scraps, in specific ASTM formulation for each elastomer, were prepared. Rheometric characteristics, mechanical properties and the morphology of the compounds developed were evaluated. With the ground scraps incorporation the vulcanization time decreases, comparing with compounds without ground scraps. The amount of scraps for the best tensile strength properties was 37 and 196 phr for SBR and EPDM compositions, respectively. Micrographs corroborated the mechanical results, indicating the best homogeneity of the scraps in the elastomeric matrix for these compositions.

  4. Ecology of toxic shock syndrome: amplification of toxic shock syndrome toxin 1 by materials of medical interest.

    Tierno, P M; Hanna, B A

    1989-01-01

    Historically, the literature suggests that staphylococcal exoproteins, including enterotoxins, are stimulated by various physicochemical ecologic factors, many of which have been shown to stimulate production of toxic shock syndrome toxin 1 (TSST-1). The propensity of different fibers and other substances to amplify TSST-1 production in toxic shock syndrome-associated strains of Staphylococcus aureus, as well as a comparative analysis of the underlying mechanisms of TSST-1 production, are reported. Two hundred twenty intravaginal devices or other products and materials and 60 experimental controls were examined for their propensity to induce TSST-1 production. Certain materials are superior to unaltered cotton in providing a more absorbent fiber--nutrients are efficiently drawn in, concentrating protein between fibers, and thereby creating an ideal physicochemical environment for the amplification of TSST-1 and other toxins. The greatest stimulation of TSST-1 was observed with (in decreasing order): polyester and carboxymethyl cellulose, polyacrylates, viscose rayon, gelatin foam, polyurethane, and cotton. No toxin was found with nasal tampons (polymer of polyvinyl acetal) or with vaginal cups (an elastomeric polymer). Results are discussed in terms of specific ecologic parameters from historical as well as recent perspectives. PMID:2928635

  5. 石墨垫片与填料中可溶性氯离子含量测定方法研究%Determination Method of Leachable Chloride in Gasketing and Packing of Plumbago Materials by Ion-Selective Electrode Technique

    陈中官

    2013-01-01

    密封垫片是现代工业生产设备中的一种重要基础元件,广泛用于管道和设备等可拆连接中.其中石墨垫片中的有害元素如硫和氯有可能对密封面造成腐蚀危害,尤其是可溶性氯离子对不锈钢密封件腐蚀更为严重.本文提出了离子选择电极测定石墨垫片与填料中可溶性氯离子含量的方法对电极检测性能及干扰离子的消除等进行了一系列的测定与讨论.

  6. High temperature range recuperator. Phase II. Prototype demonstration and material and analytical studies. Final report

    None

    1980-04-01

    A summary of the work performed to fully evaluate the commercial potential of a unique ceramic recuperator for use in recovering waste heat from high temperature furnace exhaust gases is presented. The recuperator concept being developed consists of a vertical cylindrical heat exchange column formed from modular sections. Within the column, the gasketed modules form two helical flow passages - one for high temperature exhaust gases and one for pre-heating combustion air. The column is operated in a counterflow mode, with the exhaust gas entering at the bottom and the combustion air entering at the top of the column. Activities included design and procurement of prototype recuperator modules, construction and testing of two prototype recuperator assemblies, exposure and mechanical properties testing of candidate materials, structural analysis of the modules, and assessment of the economic viability of the concept. The results of the project indicated that the proposed recuperator concept was feasible from a technical standpoint. Economic analysis based upon recuperator performance characteristics and module manufacturing costs defined during the program indicated that 3 to 10 years (depending upon pre-heat temperature) would be required to recover the capital cost of the system in combustion air preheat applications. At this stage in the development of the recuperator, many factors in the analysis had to be assumed. Significant changes in some of the assumptions could dramatically affect the economics. For example, utilizing $2.85 per mcf for the natural gas price (as opposed to $2.00 per mcf) could reduce the payback period by more than half in certain cases. In addition, future commercial application will depend upon ceramic component manufacturing technique advances and cost reduction.

  7. Gas storage materials, including hydrogen storage materials

    Mohtadi, Rana F; Wicks, George G; Heung, Leung K; Nakamura, Kenji

    2013-02-19

    A material for the storage and release of gases comprises a plurality of hollow elements, each hollow element comprising a porous wall enclosing an interior cavity, the interior cavity including structures of a solid-state storage material. In particular examples, the storage material is a hydrogen storage material such as a solid state hydride. An improved method for forming such materials includes the solution diffusion of a storage material solution through a porous wall of a hollow element into an interior cavity.

  8. Geopolymer resin materials, geopolymer materials, and materials produced thereby

    Seo, Dong-Kyun; Medpelli, Dinesh; Ladd, Danielle; Mesgar, Milad

    2016-03-29

    A product formed from a first material including a geopolymer resin material, a geopolymer resin, or a combination thereof by contacting the first material with a fluid and removing at least some of the fluid to yield a product. The first material may be formed by heating and/or aging an initial geopolymer resin material to yield the first material before contacting the first material with the fluid. In some cases, contacting the first material with the fluid breaks up or disintegrates the first material (e.g., in response to contact with the fluid and in the absence of external mechanical stress), thereby forming particles having an external dimension in a range between 1 nm and 2 cm.

  9. The materials physics companion

    Fischer-Cripps, Anthony C

    2014-01-01

    Introduction to Materials Physics: Structure of matter. Solid state physics. Dynamic properties of solids. Dielectric Properties of Materials: Dielectric properties. Ferroelectric and piezoelectric materials. Dielectric breakdown. Applications of dielectrics. Magnetic Properties of Materials: Magnetic properties. Magnetic moment. Spontaneous magnetization. Superconductivity.

  10. Nuclear materials in Japan

    2015-03-01

    The incident at Fukushima Daiichi brought materials in the nuclear industry into the spotlight. Nature Materials talks to Tatsuo Shikama, Director of the International Research Centre for Nuclear Materials, Institute for Materials Research, Tohoku University, about the current situation.

  11. Improvement and evaluation of thermal, electrical, sealing and mechanical contacts, and their interface materials

    Luo, Xiangcheng

    Material contacts, including thermal, electrical, seating (fluid sealing and electromagnetic sealing) and mechanical (pressure) contacts, together with their interface materials, were, evaluated, and in some cases, improved beyond the state of the art. The evaluation involved the use of thermal, electrical and mechanical methods. For thermal contacts, this work evaluated and improved the heat transfer efficiency between two contacting components by developing various thermal interface pastes. Sodium silicate based thermal pastes (with boron nitride particles as the thermally conductive filler) as well as polyethylene glycol (PEG) based thermal pastes were developed and evaluated. The optimum volume fractions of BN in sodium silicate based pastes and PEG based pastes were 16% and 18% respectively. The contribution of Li+ ions to the thermal contact conductance in the PEG-based paste was confirmed. For electrical contacts, the relationship between the mechanical reliability and electrical reliability of solder/copper and silver-epoxy/copper joints was addressed. Mechanical pull-out testing was conducted on solder/copper and silver-epoxy/copper joints, while the contact electrical resistivity was measured. Cleansing of the copper surface was more effective for the reliability of silver-epoxy/copper joint than that of solder/copper joint. For sealing contacts, this work evaluated flexible graphite as an electromagnetic shielding gasket material. Flexible graphite was found to be at least comparable to conductive filled silicone (the state of the art) in terms of the shielding effectiveness. The conformability of flexible graphite with its mating metal surface under repeated compression was characterized by monitoring the contact electrical resistance, as the conformability is important to both electromagnetic scaling and fluid waling using flexible graphite. For mechanical contacts, this work focused on the correlation of the interface structure (such as elastic

  12. Photorefractive Materials and Their Applications 2 Materials

    Günter, Peter

    2007-01-01

    Photorefractive Materials and Their Applications 2: Materials is the second of three volumes within the Springer Series in Optical Sciences. The book gives a comprehensive review of the most important photorefractive materials and discusses the physical properties of organic and inorganic crystals as well as poled polymers. In this volume, photorefractive effects have been investigated at wavelengths covering the UV, visible and near infrared. Researchers in the field and graduate students of solid-state physics and engineering will gain a thorough understanding of the properties of materials in photorefractive applications. The other two volumes are: Photorefractive Materials and Their Applications 1: Basic Effects. Photorefractive Materials and Their Applications 3: Applications.

  13. Silicone and Fluorosilicone Based Materials for Biomedical Applications

    Palsule, Aniruddha S.

    The biocompatibility and the biodurability of silicones is a result of various material properties such as hydrophobicity, low surface tension, high elasticity and chemical and thermal stability. A variety of biomedical implants employ an inflatable silicone rubber balloon filled with a saline solution. Commercial examples of such a system are silicone breast implants, tissue expanders and gastric bands for obesity control. Despite the advantages, saline filled silicones systems still have a certain set of challenges that need to be addressed in order to improve the functionality of these devices and validate their use as biomaterials. The central goal of this research is to identify these concerns, design solutions and to provide a better understanding of the behavior of implantable silicones. The first problem this research focuses on is the quantification and identification of the low molecular weight silicones that are not crosslinked into the elastomeric matrix and therefore can be leached out by solvent extraction. We have developed an environmentally friendly pre-extraction technique using supercritical CO 2 and also determined the exact nature of the extractables using Gas Chromatography. We have also attempted to address the issue of an observed loss of pressure in the saline filled device during application by studying the relaxation behavior of silicone elastomer using Dynamic Mechanical Analysis and constructing long-term relaxation master curves. We have also developed a technique to develop highly hydrophobic fluorinated barrier layers for the silicone in order to prevent diffusion of water vapor across the walls of the implant. This involves a hybrid process consisting of surface modification by plasma technology followed by two different coating formulations. The first formulation employed UV curable fluorinated acrylate monomers for the coating process and the second was based on Atom Transfer Radical Polymerization (ATRP) to generate a fluorinated

  14. Environmental Risk Assessment of the Olefin plant in Arya Sasol Petrochemical Complex using Fault Tree Analysis Method

    S. A. Jozi

    2014-05-01

    Conclusion: Most likely occurrence of the final event was related to the gasket unsuitable material (2×10-2. Control action to prevent the occurrence of leakage could be supplying high quality gaskets and the failure is classified in the hardware failure category.

  15. 40 CFR Appendix D to Subpart A of... - Harmonized Tariff Schedule Description of Products That May Contain Controlled Substances in...

    2010-07-01

    ... Conditioning/Heat Pump Equipment Domestic and commercial air conditioning and refrigeration equipment fall... of plastic or elastomeric materials), water and oil repellant (potentially under HS 3402),...

  16. Poliamidas, poliésteres e termoplásticos elastoméricos: uma perspectiva sustentável na indústria moderna Polyamides, polyesters and elastomeric thermoplastics: a sustainable perspective in modern industry

    Haroldo Marcos

    2012-01-01

    Full Text Available Polímeros extraídos de fontes fósseis, não biodegradáveis, são assunto cada vez mais em pauta. Seja por conta de descartes incorretos, do longo tempo que levam para se decompor no meio ambiente ou até mesmo pelo impacto socioambiental que esse tipo de material pode causar às gerações futuras. Isso nos faz indagar: como as tecnologias utilizadas por empresas do setor de polímeros têm feito surgir novos materiais? É possível oferecer soluções de menor impacto ambiental, mais resistência, mais segurança e custo menor? Ao longo deste artigo, exibiremos novos produtos e modelos de fabricação que podem tornar mais saudável e sustentável todo o caminho, que leva das grandes empresas até o consumidor final, os elementos presentes no dia-a-dia de pessoas no mundo todo.Polymers extracted from fossile sources are an issue highlighted among debates in industry, for its incorrect discard, for the long period of time this material takes to decompose or even due to its unsustainable environmental footprint. This scenario makes the industry of polymers question how the available technology can be used to create new materials, and if it would be possible to offer safer and cheaper solutions with less environmental impact and more resistance. This article will expose new products and new industrial development models that can make the chain that leads from the companies to the consumer the elements present into present-day society worldwide more sustainable.

  17. Remifentalino intravenoso mediante infusor elastomerico frente a meperidina intramuscular: Estudio comparativo en analgesia obstetrica Intravenous remifentanil delivered through an elastomeric device versus intramuscular meperidine comparative study for obstetric analgesia

    E. Calderón; Martínez, E.; M. D. Román; A. Pernio; R. García-Hernández; L. M. Torres

    2006-01-01

    Objetivos: Evaluar la eficacia y seguridad de remifentanilo administrado mediante infusor elastomérico con PCA iv en analgesia obstétrica comparado con meperidina intramuscular en parturientas con contraindicación para analgesia epidural. Material y Método: Se seleccionaron aletoriamente 24 parturientas, se asoció infusor elastomérico Baxter® con 250 ml de suero fisiológico con 2,5 mg de remifentanilo y un ritmo de 12 ml·h ¹, lo que supone una infusión media de 0,025 μg·kg-1·min-1 de rem...

  18. Investigations on Electronic Materials

    Pugnor, E.; T. Kormány

    1982-01-01

    Electronics has been described as a materials oriented technology. In this sense a short review is given concerning: the connection of materials characterization to the design and processing of electronic components; the most important materials characterization methods used for electronic materials; the strategy of organizing a complete material characterization system for selected electronic components.

  19. Sporty materials uncovered

    Kevin Edwards

    2004-01-01

    Materials in Sports Equipment is a welcome addition to books on materials engineering, says Kevin Edwards. It fills a gap in coverage of the important sports market, where advances in materials can lead to improved performance.

  20. Sporty materials uncovered

    Kevin Edwards

    2004-03-01

    Full Text Available Materials in Sports Equipment is a welcome addition to books on materials engineering, says Kevin Edwards. It fills a gap in coverage of the important sports market, where advances in materials can lead to improved performance.