WorldWideScience

Sample records for piston ring wear

  1. Investigation of piston ring – cylinder liner dry wear using a block-on-ring test rig

    DEFF Research Database (Denmark)

    Bihlet, Uffe; Klit, Peder; Felter, Christian L.;

    material combinations for piston rings and cylinder liners are examined using a block-on-ring test rig. An accelerated wear test run without lubricant is used. Results show that the morphology of cast iron is an important parameter affecting the wear resistance of the material. It is also demonstrated...

  2. Standard guide for measuring the wear volumes of piston ring segments run against flat coupons in reciprocating wear tests

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This guide covers and describes a profiling method for use accurately measuring the wear loss of compound-curved (crowned) piston ring specimens that run against flat counterfaces. It does not assume that the wear scars are ideally flat, as do some alternative measurement methods. Laboratory-scale wear tests have been used to evaluate the wear of materials, coatings, and surface treatments that are candidates for piston rings and cylinder liners in diesel engines or spark ignition engines. Various loads, temperatures, speeds, lubricants, and durations are used for such tests, but some of them use a curved piston ring segment as one sliding partner and a flat or curved specimen (simulating the cylinder liner) as its counterface. The goal of this guide is to provide more accurate wear measurements than alternative approaches involving weight loss or simply measuring the length and width of the wear marks. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its ...

  3. Step towards optimizing friction, wear and oil control in piston ring/cylinder systems

    Energy Technology Data Exchange (ETDEWEB)

    Krause, H.H.

    1986-04-01

    In a reciprocating-piston engine, cylinder liner temperature has the greatest influence on friction and lubricating film thickness. With rising liner temperature, hydrodynamic friction forces and thus friction losses decrease. At the same time, the lubricating film thicknesses on the rings drop and the mixed friction forces at TDC and BDC rise. Wear increases. With increasing speed and constant liner temperature, hydrodynamic friction and thus friction losses increase. Lubricating films become thicker, mixed friction decreases and so does wear. Under increasing pressure loads at the same liner temperature, lubricating film thicknesses decrease, especially during the expansion stroke. Mixed friction increases and so does wear. Among the various running surface profiles examined for the first compression ring, there is one optimal profile as regards friction, wear and oil control: the results confirm that the profile used on modern rings in standard production today is already optimal for today's engines, having been developed purposefully over the years. The correlations found between friction and lubricating film thickness, between mixed friction forces and ring and liner wear rates, and between lubricating thickness and oil consumption show that it is possible to determine accurately the physical correlations involved by using such a test rig, and that the results can also be applied to a fired production engine. (orig.).

  4. Stirling engine piston ring

    Science.gov (United States)

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  5. A study on the piston ring wear in automotive engine Seat 1500 CA by means of radioactive tracer technique; Estudio del desgaste de segmentos en motor Seat 1500 CA mediante trazadores radiactivos

    Energy Technology Data Exchange (ETDEWEB)

    Val Cob, M. del; Chul, Y.; Fuentes Figuera de Vargas, J.

    1971-07-01

    The iron side wear in the chromium-plated top compression ring has been a matter of interest for the engine makers and it has been required by them to investigate the wear characteristics of the chromium-plated piston ring. Meanwhile, Bureau of Nuclear Energy in Spain (Junta de Energia Nuclear) and Seat Car Manufacturing Company (Sociedad Espanola de Automoviles de Turismo) agreed to study the wear characteristics of chromium-plated piston ring of type CA gasoline engine for Seat 1500 car by means of radioactive tracer technique. (Author) 9 refs.

  6. Estimation of the operational reliability determined with Weibull modulus based on the abrasive wear in a cylinder-piston ring system

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2012-12-01

    Full Text Available Purpose: The main purpose of the study was to determine methodology for estimation of the operational reliability based on the statistical results of abrasive wear testing.Design/methodology/approach: For research, a traditional tribological system, i.e. a friction pair of the AlSi17CuNiMg silumin in contact with the spheroidal graphite cast iron of EN-GJN-200 grade, was chosen. Conditions of dry friction were assumed. This system was chosen based on mechanical cooperation between the cylinder (silumin and piston rings (spheroidal graphite cast iron in conventional internal combustion piston engines with spark ignition.Findings: Using material parameters of the cylinder and piston rings, nominal losses qualifying the cylinder for repair and the maximum weight losses that can be smothered were determined. Based on the theoretical number of engine revolutions to repair and stress acting on the cylinder bearing surface, the maximum distance that the motor vehicle can travel before the seizure of the cylinder occurs was calculated. These results were the basis for statistical analysis carried out with the Weibull modulus, the end result of which was the estimation of material reliability (the survival probability of tribological system and the determination of a pre-operation warranty period of the tribological system.Research limitations/implications: The analysis of Weibull distribution modulus will estimate the reliability of a tribological cylinder-ring system enabled the determination of an approximate theoretical time of the combustion engine failure-free running.Originality/value: The results are valuable statistical data and methodology proposed in this paper can be used to determine a theoretical life time of the combustion engine.

  7. Design of Piston Ring Friction Tester Apparatus

    DEFF Research Database (Denmark)

    Klit, Peder

    2006-01-01

    the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external load may be established by measuring the pressure distribution, i.e. the pressure drop in the piston ring package. Speed and temperature may also be established. The amount...... and forces on piston rod. Since the frictional forces are small compared to the rest of the acting forces the main design idea is to fix the piston, while the cylinder liner moves. This approach makes it simple to measure the parameters mentioned above by putting the instrumentation in the piston....

  8. Double acting stirling engine piston ring

    Science.gov (United States)

    Howarth, Roy B.

    1986-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  9. Mathematical Model of Piston Ring Sealing in Combustion Engine

    Directory of Open Access Journals (Sweden)

    Koszałka Grzegorz

    2015-01-01

    Full Text Available This paper presents a mathematical model of piston-rings-cylinder sealing (TPC of a combustion engine. The developed model is an itegrated model of gas flow through gaps in TPC unit, displacements and twisting motions of piston rings in ring grooves as well as generation of oil film between ring face surfaces and cylinder liner. Thermal deformations and wear of TPC unit elements as well as heat exchange between flowing gas and surrounding walls, were taken into account in the model. The paper contains descriptions of: assumptions used for developing the model, the model itself, its numerical solution as well as its computer application for carrying out simulation tests.

  10. Mathematical Model of Piston Ring Sealing in Combustion Engine

    OpenAIRE

    Koszałka Grzegorz; Guzik Mirosław

    2015-01-01

    This paper presents a mathematical model of piston-rings-cylinder sealing (TPC) of a combustion engine. The developed model is an itegrated model of gas flow through gaps in TPC unit, displacements and twisting motions of piston rings in ring grooves as well as generation of oil film between ring face surfaces and cylinder liner. Thermal deformations and wear of TPC unit elements as well as heat exchange between flowing gas and surrounding walls, were taken into account in the model. The pape...

  11. ІNVESTIGATION OF PECULIARITIES OF PISTON RINGS LASER BORATING

    Directory of Open Access Journals (Sweden)

    BOLSHAKOV V. I.

    2015-11-01

    Full Text Available Problem formulation. Piston rings are subject to wear while in operation. Insufficient wear resistance of materials limits the growth of machines productivity as well as the terms of their exploitation. The required complex of properties of piston rings made of cast iron cannot be always reached by applying traditional methods of heat treatment or chemical heat treatment processing. Thus, application of traditional borating methods associated with diffusion of boron into the solid phase leads to the formation of the working layer exhibiting high brittleness. Therefore, the problem of increasing the wear resistance of piston rings without embrittlement is challenging. The use oflaser heating during borating provides the formation of a new layer with special properties. However, the optimum properties can be achieved only after determining the relationship between the parameters of running a process and the depth of the borated layer. Goal of research. To determine the influence of laser heating parameters on the depth of the borated layer, as the properties of piston rings depend on the depth of the latter. Conclusions. Increase in the speed of displacing parts during laser heating reduces the depth of the borated layer, and increase of the spot diameter enhances the depth of the layer. The phases and structural components of the borated layer were interpreted by means of X-ray and metallographic methods. The results of investigations can be applied to other machine parts, which are subject to intensive wear.

  12. Numerical Simulation of Piston Ring Lubrication

    DEFF Research Database (Denmark)

    Felter, Christian Lotz

    2006-01-01

    This paper describes a numerical method that can be used to model the lubrication of piston rings. Classical lubrication theory is based on the Reynolds equation which is ap- plicable to confined geometries and open geometries where the flooding conditions are known. Lubrication of piston rings...... is extended to include also the oil film outside the piston rings. The numerical model consists of a 2D free surface code that solves the time dependent compressible Navier-Stokes equations. The equations are cast in Lagrangian form and discretized by a meshfree moving least squares method using the primitive......, however, fall outside this category of problems since the piston rings might suffer from starved running conditions. This means that the com- putational domain where Reynold equation is applicable (including a cavitation criteria) is unknown. In order to overcome this problem the computational domain...

  13. Experimental Investigation of Piston Rings for Internal Combustion Engines

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2008-01-01

    One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external l...

  14. Numerical Calculation on Altiplano Engine Cylinder Liner-piston Ring Wear%高原柴油机气缸套-活塞环磨损计算研究

    Institute of Scientific and Technical Information of China (English)

    王宪成; 和穆; 张晶; 何星

    2011-01-01

    为了研究高原环境对柴油机寿命的影响,以某型柴油机为对象,通过模拟高原柴油机实际工作过程,结合活塞环受力分析和缸套传热计算得到边界条件,基于雷诺方程和改进的Holm-Achard黏着磨损公式建立气缸套-活塞环润滑磨损数值计算模型;经验证气缸套径向最大磨损深度的计算值与实测值误差不超过5%.计算表明,油膜厚度随外界大气压力降低而逐渐变薄;在海拔5 000 m左右时气缸平均磨损值达到最大.%In order to research the operating conditions effects on diesel life, a certain diesel through simulating the actually conditions of the altiplano diesel. The cylinder liner-piston ring boundary condition was established with dynamic and heat balance analysis. The lubrication and wear calculation mode was established based on mean Reynolds equation and Holm-Achard sticking wear mechanics. The results show that, the error of the calculated value of maximum radial wear depth of cylinder liner is lower than 5% compared with the measured value. The film thickness decreases with the gradually decrease of external atmospheric pressure. At an altitude of around 5 000 m, the average radial wear depth of cylinder attains the maximum.

  15. Experimental Investigation of Piston Rings for Internal Combustion Engines

    DEFF Research Database (Denmark)

    Christiansen, Jens; Klit, Peder; Vølund, Anders;

    2007-01-01

    One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external...... forces are small compared to the rest of the acting forces the main design idea is to fix the piston, while the cylinder liner moves. This approach makes it simple to measure the parameters mentioned above by putting the instrumentation in the piston. The aim of this paper is describe the tribological...

  16. The intermetallic bonding between a ring carrier and aluminum piston alloy

    OpenAIRE

    Manasijevic, Srećko; Dolić, Natalija; Djurdjevic, Mile; Mišić, Nataša; Davitkov, Novica

    2015-01-01

    This paper presents the results of investigating the formation of intermetallic bond between a ring carrier and aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist) in order to increase the wear resistance of the first ring groove and applied in highly loaded diesel engines. Metallographic examination of the quality of alfin bond was done. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the in...

  17. Experimental Piston Ring Tribology for Marine Diesel Engines

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2008-01-01

    A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. It is often assumed that piston rings operate under fully flooded conditions, but this is not the case in real life operation. In large two-stroke engines...

  18. TRIBOLOGICAL PERFORMANCE OF PISTON RING IN MARINE DIESEL ENGINE

    DEFF Research Database (Denmark)

    Imran, Tajammal; Klit, Peder; Felter, Christian

    From a tribology point of view, it is the two dead centers that are the main area of interest for experimental study of piston rings in large marine diesel engines. Therefore, in this work the performance of piston rings is studied to mark the importance of the two dead centers. A test rig based...

  19. Role Of Computational Simulations In The Design Of Piston Rings

    Directory of Open Access Journals (Sweden)

    Novotný Pavel

    2015-06-01

    Full Text Available The paper presents computational approaches using modern strategies for a dynamic piston ring solution as a fluid structural problem. Computational model outputs can be used to understand design parameter influences on defined results of a primarily integral character. Piston ring dynamics incorporates mixed lubrication conditions, the influence of surface roughness on oil film lubrication, the influence of ring movement on gas dynamics, oil film formulation on a cylinder liner and other significant influences. The solution results are presented for several parameters of SI engine piston rings.

  20. Piston ring lubrication and hydrocarbon emissions from internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Froelund, K.

    1997-11-01

    Is it the intention with this project to improve the existing hydrocarbon emission model at the Institute by combining it with a model for predicting the piston ring lubrication. The piston ring lubrication model should be experimentally verified to ensure the validity of the model. The following items were the objectives of the current study: Develop a piston ring lubrication model. This implies the development of a ring-pack gas flow model; Examine the response of the piston ring lubrication model to changing engineer conditions. Especially, it would be interesting to look at the engine warm-up phase since this is the phase where the engine-out emissions are highest and where the commonly used three way catalyst is not capable of converting the engine-out emissions, thereby leading the engine-out emissions directly out in to the environment with the exhaust gases; In order to verify the piston ring lubrication model the lubricant distribution on the cylinder liner should be investigated experimentally. Here again it would be of great interesting to look at the engine warm-up phase; The piston ring lubrication model should be adjusted for application together with the new hydrocarbon emission model for SI-engines at the Institute in order to increase the accuracy of the latter; The piston ring lubrication model could be used for describing the transport of PAH`s in diesel engines. (EG)

  1. Computational Modelling of Piston Ring Dynamics in 3D

    Directory of Open Access Journals (Sweden)

    Dlugoš Jozef

    2014-12-01

    Full Text Available Advanced computational models of a piston assembly based on the level of virtual prototypes require a detailed description of piston ring behaviour. Considering these requirements, the piston rings operate in regimes that cannot, in general, be simplified into an axisymmetric model. The piston and the cylinder liner do not have a perfect round shape, mainly due to machining tolerances and external thermo-mechanical loads. If the ring cannot follow the liner deformations, a local loss of contact occurs resulting in blow-by and increased consumption of lubricant oil in the engine. Current computational models are unable to implement such effects. The paper focuses on the development of a flexible 3D piston ring model based on the Timoshenko beam theory using the multibody system (MBS. The MBS model is compared to the finite element method (FEM solution.

  2. The intermetallic bonding between a ring carrier and aluminum piston alloy

    Energy Technology Data Exchange (ETDEWEB)

    Manasijevie, S.; Dolie, N.; Djurdjevic, M.; Misic, N.; Davitkov, N.

    2015-07-01

    This paper presents the results of investigating the formation of intermetallic bond between a ring carrier and aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist) in order to increase the wear resistance of the first ring groove and applied in highly loaded diesel engines. Metallographic examination of the quality of al fin bond was done. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that can be made successfully as well as the formation of metal connection (alfin bond) between the ring carrier and aluminum piston alloy. (Author)

  3. Numerical simulation of piston ring in the mixed lubrication

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Piston and piston ring lubrication is a factor that strongly affects the performance of thereciprocating internal combustion engine. When the oil film thickness becomes smaller than a cer-tain value, depending upon the roughness of the surfaces in contact, mixed lubrication has to beconsidered. This paper analyzes the lubrication of piston ring and predicts pressure distribution,lubricant film thickness and surface deformation. The work is based on a unified numerical ap-proach assuming that the pressure distribution obeys Reynolds equation in hydrodynamic lubrica-tion regions while in asperities contact regions, the contact pressure can be obtained through theso-called reduced Reynolds equation. The computation experience shows the unified equationsystem is stable and can deal with severe operating conditions.

  4. Evaluation of ring surfaces with several coatings for friction,wear and scuffing life

    Institute of Scientific and Technical Information of China (English)

    Dae-Hyun CHO; Young-Ze LEE

    2009-01-01

    Friction and wear of the sliding components in an automobile cause an increase in both fuel consumption and emission. Many engine components involved with sliding contact are all susceptible to scuffing failure at some points during their operating period. Therefore, it is important to evaluate the effects of various surface coatings on the tribological characteristics of the piston ring and cylinder block surface of a diesel engine. Wear and scuffing tests were conducted using a friction and wear measurement of the piston ring and cylinder block in a low friction diesel engine. The frictional forces, wear amounts and cycles to scuffing in the boundary lubricated sliding condition were measured using the reciprocating wear tester. The tester used a piece of the cylinder block as the reciprocating specimen and a segment of the piston ring material as the fixed pin. Several coatings on the ring specimen were used, such as DLC, TiN, Cr-ceramic and TiAlN, in order to improve the tribological characteristics of the ring. The coefficients of friction were monitored during the tests, and the wear volumes of the piston ring surfaces with various coatings were compared. Test results show that the DLC coating exhibits better tribological properties than the other coatings. The graphite structure of this coating is responsible for the low friction and wear of the DLC film. The TiN and DLC coatings show better scuffing resistance than the other coatings. The TiN and Cr-ceramic coated rings show good wear resistance and high friction.

  5. A modeling of pump impeller shroud and wear-ring seal as a whole, and its application to the pump rotordynamics

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Tae Woong [Kyungwon Univ., Sungnam (Korea, Republic of); Lee, An Sung [Korea Institute of Machinery and Materials, Taejon (Korea, Republic of)

    1998-06-01

    A modeling methodology of pump impeller shroud and wear-ring seal as a whole has been developed to give its rotordynamic coefficients. In this work the governing equations are derived for the continuous flow path of the impeller shroud and wear-ring seal. Pressure loss at the discontinuity of the connecting point between the impeller shroud and the wear-ring seal is defined by utilizing a pressure loss coefficient obtained from experimental measurements. The governing equations are solved directly by using the known conditions at the inlet of the impeller shroud and outlet of the wear-ring seal. A detailed rotordynamic analysis has been carried out on a 750 m-head fourteen-stage centrifugal pump system with the effects of the hydrodynamic forces of such as impeller shroud and wear-ring seals, balance piston, and interstage seals. Results have shown that the first critical speed obtained with all the seal effects is much higher than that obtained without those effects, and moreover that the system under consideration is unstable. Large cross coupled stiffness(k) of the impeller shroud and wear-ring seal has been suspected as the source of the problem. Design modifications of the impeller shroud and wear-ring seal geometry have been performed to decrease k and increase the direct damping(C). Finally, the design modifications have yielded a stable and well damped system.

  6. Liner surface improvements for low friction piston ring packs

    Science.gov (United States)

    Anderberg, C.; Dimkovski, Z.; Rosén, B.-G.

    2014-01-01

    The development of engine components in the automotive industry is governed by several constraints such as environmental legislation and customer expectations. About a half of the frictional losses in an internal combustion engine come from the interactions between the piston assembly and cylinder liner surface. The tribological considerations in the contact between the piston ring and cylinder liner have attracted much attention over the past few decades. Many non-conventional cylinder liner finishes have been, and are being, developed with the aim to reduce friction losses and oil consumption, but the effects of the surface finish on piston ring pack performance is not well understood. One way of reducing friction in the cylinder system is to reduce the tangential load from the piston ring pack, focusing on the oil control ring. However, the side-effect of this is a disappointingly increased oil consumption. In this study a number of different cylinder liner surface specifications were developed and implemented in test engines with the aim of maintaining the level for oil consumption when decreasing the tangential load for the piston ring pack. To improve our understanding of the result, the same surfaces were evaluated in elastic and elasto-plastic rough contact and hydrodynamic flow simulation models. It is shown that oil consumption is strongly related to surface texture on the cylinder liners and at lower speeds (900-1200 rpm), a ‘rougher surface’ with a high core (e.g. Sk) and valley roughness (e.g. Svk) results in higher oil consumption. At the medium speed range (1200-3600 rpm), oil consumption continues to dominate for the ‘rough’ surfaces but with a visible influence of a lower oil consumption for a decreased roughness within the ‘rough’ surface group. ‘Smooth’ surfaces with a ‘smooth’ core (Sk), irrespective of the valley component (Svk), show similar oil consumption. For engine speeds above 3600 rpms, an increase in plateau

  7. YAG激光微坑刻蚀分布对缸套-活塞环摩擦磨损性能影响%Friction and Wear Properties of Cylinder Liner and Piston Ring with Different YAG Laser Honing Micro-Pits Distributions

    Institute of Scientific and Technical Information of China (English)

    占剑; 杨明江

    2011-01-01

    通过改变激光刻蚀微坑面积占有率Sp及微坑分布角度θ等参数,测得摩擦副运行过程中缸套-活塞环间摩擦系数及缸套下试块磨损量,研究激光刻蚀工艺对缸套-活塞环摩擦副摩擦磨损性能的影响.得出在其他参数不变,θ为30°时,摩擦副间温度及摩擦系数最低,θ为45°时,磨损量最小;深径比为0.1、θ为30°时,Sp为35%,摩擦磨损特性最佳.将激光刻蚀缸套与机械珩磨摩擦磨损特性进行比较,激光微坑刻蚀得到了更低的摩擦系数和更小的磨损量.%To study the effect of laser honing on friction and wear properties, the friction coefficient between cylinder liner testing block and piston ring as well as the wear of bottom cylinder liner testing block were measured by varying area density of micro-pits Sp and micro-pits distribution angle θ. Results show that temperature and friction coefficient between the friction pairs reach their minimum values at θ= 30°, and the wear gives its lowest value at θ= 45°. Best friction and wear properties achieves ate = 0.1, θ = 30°, Sp = 35%. Compared with the mechanical honing, the laser honing gives the lower friction coefficient and less wear.

  8. Aluminizing and subsequent nitriding of plain carbon low alloy steels for piston ring applications

    Energy Technology Data Exchange (ETDEWEB)

    Bindumadhavan, P.N.; Keng Wah, H.; Prabhakar, O. [Nanyang Technol. Univ., Singapore (Singapore). Div. of Mater. Eng.; Makesh, S. [Chemical and Nuclear Engineering Building, University of Maryland, 20783, College Park, MD (United States); Gowrishankar, N. [I P Rings Ltd., D 11/12, Industrial Estate, 603209, Maraimalainagar (India)

    2000-05-22

    Nitriding is a case hardening process that is commonly used for increasing the wear life of automotive piston rings. However, special alloy steels are required to achieve high surface hardness and nitrided case depth values required by the automotive industry. The cost of such alloy steels is one of the major components of the total cost of the nitrided piston ring. To address this issue, efforts have been directed towards development of cheaper raw materials as substitutes for nitridable steels. In this study, an attempt has been made to increase the surface hardness of two plain carbon low alloy steels by aluminizing and subsequent diffusion treatment and nitriding. The process parameters for the aluminizing operation are discussed. Results indicate that a near twofold increase in surface hardness is achievable by aluminizing followed by diffusion treatment and nitriding (580-1208 HV for EN32B steel and 650-1454 HV for 15CR3 steel). It has also been found that the nitrided case depth obtained (0.11-0.13 mm for EN32B steel and 0.10-0.14 mm for 15CR3 steel) matches well with the general requirements of the piston ring industry. The diffusion of aluminum into the alloy layer has also been discussed and the theoretical predictions were compared with actual values of Al concentration, as obtained by SEM-EDS system. It is found that Fick's law gives a fairly good prediction of the actual Al concentration profile, in spite of the complexity of the diffusion path. X-Ray diffraction studies have confirmed the presence of AlN in the alloy layer, which could be instrumental in the significant increase in surface hardness. It is proposed that aluminizing followed by diffusion treatment and nitriding of plain carbon low alloy steels could provide an alternative to the use of expensive nitridable steels for piston ring applications. (orig.)

  9. Piston

    Energy Technology Data Exchange (ETDEWEB)

    Donahue, Richard J [Colgate, WI

    2009-03-24

    A number of embodiments of a piston may have a shape that provides enhanced piston guidance. In such embodiments, the piston shape may include an axial profile that is configured to provide certain thrust load characteristics.

  10. Piston

    Energy Technology Data Exchange (ETDEWEB)

    Donahue, Richard J [Colgate, WI

    2009-02-24

    A number of embodiments of a piston may have a shape that provides enhanced piston guidance. In such embodiments, the piston shape may include an axial profile that is configured to provide certain thrust load characteristics.

  11. Effects of Surface Irregularities on Piston Ring-Cylinder Tribo Pair of a Two Stroke Motor Engine in Hydrodynamic Lubrication

    Directory of Open Access Journals (Sweden)

    A. Zavos

    2015-03-01

    Full Text Available Tribological parameters such as friction, lubrication and wear influence strongly the engine component's life. In this study, a piston ring-cylinder system simulated taking into account the surface modifications under fully flooded lubrication and normal engine conditions. The hydrodynamic pressure field solved based on the Navier Stokes equations by Fluid Structure Interaction analysis. A real experimental data of piston ring-cylinder was used from a two stroke motor engine 50 cc. The surface irregularities are measured by 3D coordinate measurement machine while the engine has been worked about 4000 hours. The friction force, the hydrodynamic pressure, the oil film and the mechanical stresses were predicted for different engine conditions. Results show that the worn profile ring reduces the friction as well as the mechanical stresses increased. Surface condition of worn top ring was observed after a metallurgical profile analysis.

  12. Development and verification of a reciprocating test rig designed for investigation of piston ring tribology

    DEFF Research Database (Denmark)

    Pedersen, Michael Torben; Imran, Tajammal; Klit, Peder

    2009-01-01

    This paper describes the development and verification of a reciprocating test rig, which was designed to study the piston ring tribology. A crank mechanism is used to generate a reciprocating motion for a moving plate, which acts as the liner. A stationary block acting as the ring package is loaded......, which is suitable for the study of piston ring tribology....

  13. Effects of Nano-Particles on the Tribological and Thermal Properties of Piston Ring-Cylinder Liner

    Institute of Scientific and Technical Information of China (English)

    刘小君; 刘焜; 焦明华; 王伟; 丁曙光

    2004-01-01

    The effects of ultra-dispersed diamond (UDD) on the friction force, wear, and temperature of tribological pairs have been investigated.The experimental tests were carried out on a modified piston ring-cylinder liner bench tester with different particle mass fractions of 0, 0.02%, and 0.10%.The results show that compared with a pure fluid, the mixture of the fluid and UDD not only reduces the friction and wear, but also reduces the bulk temperature of the specimen.The mechanism by which the UDD lubricant improves the tribological properties has some relationship with surface topography, because it can increase the bearing capability of surfaces.

  14. Tribological Properties of IF-MoS2 Nanoparticles as Lubricant Additive on Cylinder Liner and Piston Ring Tribo-pair

    Directory of Open Access Journals (Sweden)

    M.S. Charoo

    2016-06-01

    Full Text Available Friction and wear behaviors of different concentrations of IF-MoS2 nanoparticles in SAE 20W40 were studied. First of all tribological tests with SAE 20W40 + IF-MoS2 were carried out on a four ball wear test machine as per ASTM D 4172 standard to study its wear properties. Detailed friction and wear studies on cylinder liner and piston ring tribo-pair were conducted on pin-on-block universal tribometer under lubricated conditions of SAE 20W40+ IF-MoS2. These experimental studies were conducted at different operating parameters to ascertain the influence of nanoadditive on friction and wear of cylinder liner and piston ring tribo-pair. A minimum coefficient of friction of 0.0772 was observed for 0.5 wt% of IF-MoS2 at normal load of 100 N at sliding velocity of 0.03 m/sec. A substantial reduction of 65 % in the wear of cylinder liner and piston ring tribo-pair was also observed when lubricated with SAE 20W40 and 0.5 wt% of IF-MoS2. Scanning electron microscopy and energy dispersive spectrometry analysis of the worn out surfaces was also carried out to find the causes for observed friction and wear behavior.

  15. Novel Tribotester for Cylinder Liner/Piston Ring Contacts of Two Stroke Marine Diesel Engines

    DEFF Research Database (Denmark)

    Pedersen, Michael Torben; Imran, Tajammal; Klit, Peder

    2009-01-01

    A good tribological description for the cylinder liner and piston ring materials is always desired in order to achieve an improved combination of the materials. The piston ring package in a two-stroke-diesel engine operates in three lubrication regimes and the materials must be characterized in r...

  16. Tribological properties of IF-MoS2 nanoparticles as lubricant additive on cylinder liner and piston ring tribo-pair

    OpenAIRE

    Charoo, M.S.; Wani, Mohammad Farooq

    2016-01-01

    Friction and wear behaviors of different concentrations of IF-MoS2 nanoparticles in SAE 20W40 were studied. First of all tribological tests with SAE 20W40 + IF-MoS2 were carried out on a four ball wear test machine as per ASTM D 4172 standard to study its wear properties. Detailed friction and wear studies on cylinder liner and piston ring tribo-pair were conducted on pin-on-block universal tribometer under lubricated conditions of SAE 20W40+ IF-MoS2. These experimental studies were conducted...

  17. The intermetallic bonding between a ring carrier and aluminum piston alloy

    Directory of Open Access Journals (Sweden)

    Manasijevic, Srećko

    2015-09-01

    Full Text Available This paper presents the results of investigating the formation of intermetallic bond between a ring carrier and aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist in order to increase the wear resistance of the first ring groove and applied in highly loaded diesel engines. Metallographic examination of the quality of alfin bond was done. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that can be made successfully as well as the formation of metal connection (alfin bond between the ring carrier and aluminum piston alloy.El artículo presenta los resultados de la investigación sobre la formación de una unión intermetálica entre el portasegmento y la aleación de aluminio del pistón. El portasegmento es una fundición de hierro austenítico (Ni-Resist con el fin de aumentar la resistencia al desgaste de la unión Al-fin del primer segmento y se utiliza en motores diésel altamente cargados. Se realizó un examen metalográfico de la unión intermetálica, mediante un microscopio óptico en combinación con SEM/EDS. Los satisfactorios resultados obtenidos muestran la formación de contacto metálico (unión Al-fin del primer segmento entre el portasegmento y la aleación de aluminio del pistón.

  18. Investigation of Different Piston Ring Curvatures on Lubricant Transport along Cylinder Liner in Large Two-Stroke Marine Diesel Engines

    DEFF Research Database (Denmark)

    Overgaard, Hannibal Christian; Klit, Peder; Vølund, Anders

    2016-01-01

    A theoretical investigation of the hydrodynamic lubrication of the top compression piston ring in a large two-stroke marine diesel engine is presented. The groove mounted piston ring is driven by the reciprocal motion of the piston. The ring shape follows a circular geometry and the effect...

  19. Pistonics

    DEFF Research Database (Denmark)

    Perram, John W.; Præstgaard, Eigil; Smith, Edgar R.

    2011-01-01

    is proportional to its internal energy. We report molecular dynamics experiments with ideal gas particles and show that they can exchange energy with their container. We then construct a dynamical system modelling the motion of the piston and heat transfer to the surroundings when the piston is released...

  20. PISTON

    Energy Technology Data Exchange (ETDEWEB)

    Sewell, Christopher Meyer [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-01-08

    This presentation was a part of the guest lecture series for graduate classes at the University of Oregon on many-core visualization. It discussed a practical introduction to high-level data parallelism using thrust and PISTON; presented an overview of PISTON and PINION; provided tutorial examples; additional details on research results.

  1. Standard test method for conducting friction tests of piston ring and cylinder liner materials under lubricated conditions

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method covers procedures for conducting laboratory bench-scale friction tests of materials, coatings, and surface treatments intended for use in piston rings and cylinder liners in diesel or spark-ignition engines. The goal of this procedure is to provide a means for preliminary, cost-effective screening or evaluation of candidate ring and liner materials. A reciprocating sliding arrangement is used to simulate the contact that occurs between a piston ring and its mating liner near the top-dead-center position in the cylinder where liquid lubrication is least effective, and most wear is known to occur. Special attention is paid to specimen alignment, running-in, and lubricant condition. 1.2 This test method does not purport to simulate all aspects of a fired engine’s operating environment, but is intended to serve as a means for preliminary screening for assessing the frictional characteristics of candidate piston ring and liner material combinations in the presence of fluids that behave as u...

  2. Wear and Corrosion of Cast Al Alloy Piston with and without Brake Oil

    Directory of Open Access Journals (Sweden)

    Olawale Olarewaju Ajibola

    2015-01-01

    Full Text Available The effects of wear and corrosion of cast AA6061 aluminium alloy were studied with and without brake fluid using a wear jig while the corrosion rate was determined in brake fluid for 70 days under two experimental set-ups. The tests, yielded 0.00000123 g/mm2/min highest wear rate at 147000 wear cycles and 0.0334 mg/mm2/yr as the highest corrosion rate within the early 39th day of immersion in oil, the values being considered comparatively lower than those obtained for Al alloy in most common wet abrasion test and corrosion in aqueous solutions as previously reported in literature. The material loss rates to wear and corrosion were determined from the equations relating to wear and corrosion based on the ASTM designations. The results show that the combined actions of wear and corrosion contribute to the total loss of piston material immersed in brake oil. This is greater than either of their effects individually on cast Al alloy in the brake oil.

  3. A dual-piston ring-driven X-spring transducer

    Science.gov (United States)

    Butler, Alexander L.; Butler, John L.; Pendleton, Robert L.; Ead, Richard M.

    2004-05-01

    Tonpilz transducers generally consist of a stack of piezoelectric material sandwiched between a single piston and an inertial tail mass or between two pistons. The result is a transducer with a large length-to-diameter ratio. The X-spring transducer design, based on U.S. Patent 4845688, allows a means for a shorter transducer length through an orthogonal piezoelectric drive system coupled to the pistons by lever arms. We present here a low-frequency, dual-piston piezoelectric ceramic ring driven version with a length of only 10 in. and a diameter of 19 in. Both single-element and two-element array results are presented. The measured response is shown to be in agreement with the finite-element model with a smooth, wideband 300- to 550-Hz response for this dual-piston, ring-driven X-spring transducer. [Work supported by a Phase II SBIR, through NUWC, Newport, RI 02841.

  4. Test Method Designed to Evaluate Cylinder Liner-Piston Ring Coatings for Advanced Heat Engines

    Science.gov (United States)

    Radil, Kevin C.

    1997-01-01

    Research on advanced heat engine concepts, such as the low-heat-rejection engine, have shown the potential for increased thermal efficiency, reduced emissions, lighter weight, simpler design, and longer life in comparison to current diesel engine designs. A major obstacle in the development of a functional advanced heat engine is overcoming the problems caused by the high combustion temperatures at the piston ring/cylinder liner interface, specifically at top ring reversal (TRR). Therefore, advanced cylinder liner and piston ring materials are needed that can survive under these extreme conditions. To address this need, researchers at the NASA Lewis Research Center have designed a tribological test method to help evaluate candidate piston ring and cylinder liner materials for advanced diesel engines.

  5. Tribological Performance of Different Geometries of Piston Rings in Marine Diesel Engines

    DEFF Research Database (Denmark)

    Imran, Tajammal; Klit, Peder; Felter, Christian

    are manufactured from real piston ring material. The mating slider is manufactured from cylinder liner material. Experiments are conducted at five different speeds and a fixed dead-weight loading. The friction force and the bulk temperature of the test specimen are recorded as a function of crank angle position...... centres. A theoretical model is developed to predict the performance of piston rings throughout the entire cycle. This model is based on Reynolds equation coupled with a pressure-density relation for modelling of cavitation. It is assumed that the infinite width bearing assumption is valid, which...... effectively reduces the spatial dimension by 1. The viscosity of the oil is based on a tabulated viscosity-temperature relation and the measured temperature of the piston ring segments. Thus, it is not necessary to include the energy equation in the theoretical model. Asperity interaction is included...

  6. Tribological Performance of Different Geometries of Piston Rings in Marine Diesel Engines

    DEFF Research Database (Denmark)

    Imran, Tajammal; Klit, Peder; Felter, Christian

    effectively reduces the spatial dimension by 1. The viscosity of the oil is based on a tabulated viscosity-temperature relation and the measured temperature of the piston ring segments. Thus, it is not necessary to include the energy equation in the theoretical model. Asperity interaction is included...... centres. A theoretical model is developed to predict the performance of piston rings throughout the entire cycle. This model is based on Reynolds equation coupled with a pressure-density relation for modelling of cavitation. It is assumed that the infinite width bearing assumption is valid, which...... in the model. Conservation of oil is ensured by considering the amount of oil outside the piston ring/liner interface. In order to validate the theoretical model a reciprocating lab scale test apparatus has been developed. Straight test specimens with radii of curvature of 80 mm, 160 mm, and 240 mm...

  7. Syntheses and Tribological Property of CrMoN/MoS2 Multilayer Films on Piston Rings of Heavy Vehicle Engine

    Institute of Scientific and Technical Information of China (English)

    WANG Xiancheng; LI Qi; LI Ruoting; DI Yuelan

    2016-01-01

    In order to prolong the service life of piston rings of heavy vehicle engine and decrease the friction and wear of piston rings and cylinder liner, CrMoN/MoS2 multilayer iflms were deposited on the surface of rings by magnetron sputtering and low temperature ion sulfuration. FESEM equipped with EDX was adopted to analyze the compositions and morphologies of surface, cross-section, and wear scars of the multilayer iflms. The nano-hardness and Young’s modulus of the iflms were measured by a nano tester. Tribological properties of the iflms were tested by an SRV®4 wear tester. The experimental results indicate that the structures of the multilayer films are dense and compact. The films possess nano hardness value of approximately 26.7 GPa and superior ability of plastic deformation resistance. The multilayer iflms can activate solid lubricating, and possess an excellent antifriction and wear resistance under the conditions of heavy load, high frequency, high temperature, and dynamic load.

  8. Lead-free, bronze-based surface layers for wear resistance in axial piston hydraulic pumps

    Energy Technology Data Exchange (ETDEWEB)

    Vetterick, Gregory Alan [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Concerns regarding the safety of lead have provided sufficient motivation to develop substitute materials for the surface layer on a thrust bearing type component known as a valve plate in axial piston hydraulic pumps that consists of 10% tin, 10% lead, and remainder cooper (in wt. %). A recently developed replacement material, a Cu-10Sn-3Bi (wt.%) P/M bronze, was found to be unsuitable as valve plate surface layer, requiring the development of a new alloy. A comparison of the Cu-1-Sn-10Pb and Cu-10Sn-3Bi powder metal valve plates showed that the differences in wear behavior between the two alloys arose due to the soft phase bismuth in the alloy that is known to cause both solid and liquid metal embrittlement of copper alloys.

  9. Design of self-adjusting tribo-tester fixture for piston ring%活塞环自调心夹具摩擦学试验设计

    Institute of Scientific and Technical Information of China (English)

    秦襄培; 吴丽; 鄢宁波; 曾诚; 武胜超

    2015-01-01

    为了研究活塞环的摩擦学问题,要使用活塞环上直接截取的一段试样进行实验,如果使用常规夹具,非对称的桶面活塞环作为销试样垂直于盘试样,不能保证摩擦接触面在工作面上,因此设计了一种活塞环自调心夹具,使得活塞环试样可以倾斜放置. 在随后的活塞环表面改性的筛选试验中,使用了所设计的新夹具,实验结果显示,盘试样和环试样的磨损量分别降低了1.5倍和2.3倍,实验筛选区分效果明显,自调心夹具可以满足实验要求.%To study the tribological problem of piston ring, a section cut from real piston is used to do exper-iment. If the convention fixture is used, the unsymmetrical drum piston ring is perpendicular to disc, which cannot guarantee friction surface lies on working surface. A self-adjusting fixture was designed to ensure that the piston ring sample can be inclined. The new designed fixture was used in the following screening tests of piston ring surface modification. The results show that the wear loss of disc sample and the ring sample de-crease 1.5 and 2.3 times respectively. Results of screening test are distinguished, and the self-adjusting fix-ture can meet the requirements of the experiment.

  10. Lubrication of Piston Rings in Large 2–and 4–stroke Diesel Engines

    DEFF Research Database (Denmark)

    Felter, Christian Lotz

    is fulfilled in a quasi-static sense a concrete example is analyzed using the Reynolds equation. Next a free surface 2D code based on the compressible Navier–Stokes equations is developed. The main idea is to model also the oil film outside the piston ring. Through time integration the movement of the inlet...

  11. Investigation of friction characteristics in segmented piston ring liner assembly of IC engine

    Directory of Open Access Journals (Sweden)

    Tejaskumar Chaudhari

    2016-09-01

    Full Text Available The friction at the piston ring cylinder liner assembly (PRLA is a major contributor in the total friction losses in the I.C. engine. New materials, coatings and high-tech machining processes that previously were considered to be too expensive and therefore only used in complex applications are today becoming more affordable. A significant amount of the total power loss in a modern automotive engine is due to the Friction interaction between the top compression ring and the cylinder liner, especially at the TDC and BDC where boundary lubrication exists. The change in piston speed is accompanied with change the lubrication regime in the cylinder, which results change in friction between the ring and the liner during the entire stroke of the piston. Theoretical modelling of friction force from the various sources of friction will be compared to experimental results for analysing the tribological characteristics. The appropriate sample of piston ring and cylinder liner pair is developed for studying the different tribological parameters on Reciprocating Tribometer. The variable parameters are engine speed, oil viscosity, and load. The experimental results and observations are studied under different operating conditions in speed ranges from 300 rpm to 1500 rpm with constant load of 60 N. It can be seen that as speed increases, the friction force and friction coefficient also decreases.

  12. The behaviour of inlet roughness in lubrication of piston ring-cylinder liner

    Institute of Scientific and Technical Information of China (English)

    KristianTφNDER

    2001-01-01

    The improvement of lubrication of piston ring-cyinder liner is always in demand, andsurface roughness behaviour plays a very important role. The present paper will explore this be-haviour and investigate how the inlet roughness of ring influences the lubrication of pistonring-cylinder. The quantitative results of this combination of surface roughness on friction force, oilfilm thickness and frictional power loss are given and discussed.

  13. Effects of Geometrical Clearances, Supports Friction, and Wear Rings on Hydraulic Actuators Bending Behavior

    Directory of Open Access Journals (Sweden)

    Sergio Baragetti

    2016-01-01

    Full Text Available Hydraulic actuators are commonly adopted in machines and structures to provide translating forces with significant magnitudes. Although their application dates back to the industrial revolution, their bending behavior under compression is typically addressed by simple Euler’s instability analysis on the rod, neglecting effects such as the cylinder inertia and stiffness, the presence of contact elements in the cylinder-rod junction and on the piston, geometrical misalignments and imperfections, and friction moments at the support. Such simplifications lead to unjustified reduced critical load calculations on the component. In the present paper, a complete mathematical formulation, which accounts for such effects, is presented and validated against experimental data. A numerical sensitivity analysis is conducted, to assess the contributions of initial rectilinear imperfections, wear rings stiffness and dimension, and supports friction on the actuator’s limit buckling load and bending behavior under compression. Results are presented, including the effect of the cited parameters on the buckling load, providing a reliable tool for the mechanical designer. In particular, an optimum position for the wear ring distance is found. Moreover, increased wear ring stiffness and reduced imperfections increase the buckling load and reduce the bending stresses before the critical load.

  14. A new production technique for wear resistant ring-hammers

    Directory of Open Access Journals (Sweden)

    Li Shifeng

    2011-11-01

    Full Text Available Based on a great number of laboratory experiments, a new technique has been developed for producing wear resistant ring-hammers. In this technology, lost foam casting with iron sand was combined to make mold; a special alloy was used to inoculate the molten steel, and proper heat treatment was used to further improve mechanical properties of wear resistant ring-hammers. The influence of this new production technology on the microstructure and mechanical properties of wear resistant ring-hammers was studied. Results show that iron sand molding, having the inherent characteristic of sand molding, changes the type of metallic compounds, refines crystal grains and increases the fineness of microstructure. Practical experience verified that the properties of the ring-hammers produced with this new technique are as follows: tensile strength (Rm 720 MPa, impact toughness (ak > 210 J•cm-2 and hardness > 200 HB. After water quenching from 1,080℃ (holding for 4 h and tempering at 320℃ for 3 h, the best wear resistance is obtained, and the wear resistance is 1.6 times higher than that of common high manganese ring-hammers.

  15. Point Lepreau primary heat transport pump wear ring cracking

    Energy Technology Data Exchange (ETDEWEB)

    Licina, G. [Structural Integrity Associates, Inc., San Jose, California (United States); Rankin, B. [Point Lepreau Nuclear Generating Station, Fredericton, New Brunswick (Canada)

    2011-07-01

    The number 3 Primary Heat Transport (PHT) pump from Point Lepreau Nuclear Generating Station (Point Lepreau) was disassembled after more than 30 years of service for inspection during station refurbishment. The disassembly and inspection were performed to provide assurance of continued satisfactory operation during life extension. The inspection revealed cracks in the wear ring, at and near the tack welds (Type 309 stainless steel weld metal) at the cap screws that attach the Type 420 stainless steel wear ring to the body of the pump. Investigative work consisted of on-site PT and replication of the microstructure at the surface of the wear ring, subsequent impressions of two crack faces, and hardness determinations. This paper describes the investigative work and conclusions associated with resolution of the following questions: 1. What is the most likely cause of the cracking? 2. Will the cracks propagate within the base metal of the wear ring? 3. If propagation is possible, what is the risk of cracks intersecting, such that a piece of metal could become dislodged? Question number 3 has clear ramifications with respect to foreign material entering and damaging a nuclear fuel-containing pressure tube. There are also questions associated with extent of condition, specifically, whether other PHT pumps may have similar or worse cracking and whether such cracks will grow. Results will be applied to wear rings in other PHT pumps at Point Lepreau and are likely to be applicable to similar components in other CANDU PHT pumps. (author)

  16. Influence of sliding surface roughness and oil temperature on piston ring pack operation of an automotive IC engine

    Science.gov (United States)

    Wolff, A.

    2016-09-01

    In the paper a comprehensive model of a piston ring pack motion on an oil film has been presented. The local oil film thickness can be compared to height of the combined roughness of sliding surfaces of piston rings and cylinder liner. Equations describing the mixed lubrication problem based on the empirical mathematical model formulated in works of Patir, Cheng and Greenwood, Tripp have been combined and used in this paper. The developed model takes the following phenomena into account: hydrodynamic and contact forces, spring and gas forces acting on piston rings. The rings motion concerning low and high temperature of cylinder surface has been compared. These results concern cases of hydrodynamic and mixed lubrication. Changes of oil wetted area and contact zone of piston rings have been shown. In addition the oil film thickness distribution along cylinder liner and all the forces acting on piston rings have been analysed and discussed. The results have been presented in form of relevant diagrams. The developed model and software can be utilized for optimization of piston rings design.

  17. EXPERIMENTAL INVESTIGATION ON PARTICLE EFFECT IN PISTON RING-CYLINDER LUBRICATION

    Institute of Scientific and Technical Information of China (English)

    LIU Kun; LIU Xiaojun; WANG Wei; JIAO Minghua

    2006-01-01

    To study the tribological properties of the piston ring-cylinder liner in liquid-solid lubrication, the experiment is carried out on a modified piston ring-cylinder liner tester. Two kinds of liquid-solid lubricants are used, one with ultra-dispersed diamond (UDD) nano-particles suspending in pure lubricant, the other with micro-sized MoS2 particles. The particle concentrations are 0%, 0.02%and 0.1% by weight. The experimental temperature is 30 ℃ and 75 ℃ respectively. The results show that with the presence of ultra-dispersed diamond particles, the load when scuffing failure occurs is increased. For the lubricant contains MoS2 particles, the scuffing load is decreased. The liquid-solid lubricant also affects the thermal behavior of piston ring-cylinder liner. The surface bulk temperatures of cylinder liner specimen are measured. It has been seen that liquid-solid lubricant used in this research tends to improve the thermal properties generally and the measured friction forces also decreases with the presence of UDD nano-particles. The surface bulk temperature when scuffing occurs is also measured. The results show that the size effect and environment temperature have obvious influence on scuffing load and scuffing temperature. With some new findings, this work is an important complement to the existing research on particle effect on lubrication, because the existing results only show one aspect of this problem.

  18. Nonlinear quantum piston for the controlled generation of vortex rings and soliton trains

    KAUST Repository

    Pinsker, Florian

    2013-05-29

    We propose a simple way to generate nonlinear excitations in a controllable way by managing interactions in Bose-Einstein condensates. Under the action of a quantum analog of a classical piston, the condensed atoms are pushed through the trap, generating vortex rings infully three-dimensional condensates or soliton trains in quasi-one-dimensional scenarios. The vortex rings form due to transverse instability of the shock-wave train, enhanced and supported by the energy transfer between waves. We elucidate in what sense the self-interactions within the atom cloud define the properties of the generated vortex rings and soliton trains. Based on the quantum-piston scheme we study the behavior of two-component Bose-Einstein condensates and analyze how the presence of an additional superfluid influences the generation of vortex rings or solitons in the other component, and vice versa. Finally, we show the dynamical emergence of skyrmions within two-component systems in the immiscible regime. © 2013 American Physical Society.

  19. Calculation of Oil Film Thickness from Damping Coefficients for a Piston Ring in an Internal Combustion Engine

    DEFF Research Database (Denmark)

    Christiansen, Jens; Klit, Peder; Vølund, Anders

    2007-01-01

    engine. The basic idea is to use the fluid film damping coefficients to estimate the film thickness variation for a piston ring under cyclic varying load. Reynolds Equation is solved for a piston ring and the oil film thickness is determined. In this analysis hydrodynamic lubrication is assumed......In 1966 Jorgen W. Lund published an approach to find the dynamic coefficients of a journal bearing by a first order perturbation of the Reynold's equation. These coefficients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In the mid seventies Jorgen...... W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. In the present paper this method is further developed and utilized to determine the dynamic behavior of a piston ring in a combustion...

  20. Analysis of the piston ring/liner oil film development during warm-up for an SI-engine

    DEFF Research Database (Denmark)

    Frølund, Kent; Schramm, Jesper; Tian, T.;

    2001-01-01

    A one-dimensional ring-pack lubrication model developed at MIT is applied to simulate the oil film behavior during the warm-up period of a Kohler spark ignition engine. This is done by making assumptions for the evolution of the ail temperatures during warm-up and that the oil control ring during...... downstrokes is fully, flooded. The ring-pack lubrication model includes features such as three different lubrication regimes, i.e., pure hydro-dynamic lubrication, boundary lubrication and pure asperity contact, nonsteady wetting of both inlet and outlet of the piston ring, capability to use all ring face...

  1. Wear and Corrosion of Cast Al Alloy Piston with and without Brake Oil

    OpenAIRE

    Olawale Olarewaju Ajibola; Daniel Toyin Oloruntoba

    2015-01-01

    The effects of wear and corrosion of cast AA6061 aluminium alloy were studied with and without brake fluid using a wear jig while the corrosion rate was determined in brake fluid for 70 days under two experimental set-ups. The tests, yielded 0.00000123 g/mm2/min highest wear rate at 147000 wear cycles and 0.0334 mg/mm2/yr as the highest corrosion rate within the early 39th day of immersion in oil, the values being considered comparatively lower than those obtained for Al alloy in most common ...

  2. Wear Resistance of Piston Sleeve Made of Layered Material Structure: MMC A356R, Anti-Abrasion Layer and FGM Interface

    Directory of Open Access Journals (Sweden)

    Hernik Szymon

    2016-09-01

    Full Text Available The aim of this paper is the numerical analysis of the one of main part of car engine – piston sleeve. The first example is for piston sleeve made of metal matrix composite (MMC A356R. The second improved material structure is layered. Both of them are comparison to the classical structure of piston sleeve made of Cr-Ni stainless steel. The layered material structure contains the anti-abrasion layer at the inner surface of piston sleeve, where the contact and friction is highest, FGM (functionally graded material interface and the layer of virgin material on the outer surface made of A356R. The complex thermo-elastic model with Archard's condition as a wear law is proposed. The piston sleeve is modelling as a thin walled cylindrical axisymmetric shell. The coupled between the formulation of thermo-elasticity of cylindrical axisymmetric shell and the Archard’s law with functionally changes of local hardness is proposed.

  3. Ceramics Technology Project database: September 1991 summary report. [Materials for piston ring-cylinder liner for advanced heat/diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Keyes, B.L.P.

    1992-06-01

    The piston ring-cylinder liner area of the internal combustion engine must withstand very-high-temperature gradients, highly-corrosive environments, and constant friction. Improving the efficiency in the engine requires ring and cylinder liner materials that can survive this abusive environment and lubricants that resist decomposition at elevated temperatures. Wear and friction tests have been done on many material combinations in environments similar to actual use to find the right materials for the situation. This report covers tribology information produced from 1986 through July 1991 by Battelle columbus Laboratories, Caterpillar Inc., and Cummins Engine Company, Inc. for the Ceramic Technology Project (CTP). All data in this report were taken from the project's semiannual and bimonthly progress reports and cover base materials, coatings, and lubricants. The data, including test rig descriptions and material characterizations, are stored in the CTP database and are available to all project participants on request. Objective of this report is to make available the test results from these studies, but not to draw conclusions from these data.

  4. Failure analysis of wear of main clutch separating ring of heavy vehicles

    Institute of Scientific and Technical Information of China (English)

    SUN Xiao-long; LI Xiao-yan; ZHU You-li; XU Bin-shi

    2005-01-01

    The severe wear of separating ring is considered to be a main reason which leads to the improper declutch of the main clutch of heavy vehicles. The wear mechanism of the separating ring is not well understood. Scanning electron microscopy and transmission electron microscopy were employed to analyze the surface features and dislocation characteristics of the separating ring. The typical features of furrows and rolled tongue-like metal were found on the surface of separating ring by scanning electron microscopy observation, which can be considered as a major indi cation of the grain-abrasion. A zone of high density dislocation was noted on the subsurface of the separating ring by transmission electron microscopy observation, which implies the contribution of the severe impact on the surface of the separating ring in the wear process. The influences of the structure of the separating ring, the service condition and the in-service stress distribution on the wear behavior, were also analyzed. The results show that the failure of separating ring results from the impact wear and grain-abrasion together with the plastic deformation.

  5. Standard test method for ranking resistance of plastics to sliding wear using block-on-ring wear test—cumulative wear method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This test method covers laboratory procedures for determining the resistance of plastics to sliding wear. The test utilizes a block-on-ring friction and wear testing machine to rank plastics according to their sliding wear characteristics against metals or other solids. 1.2 An important attribute of this test is that it is very flexible. Any material that can be fabricated into, or applied to, blocks and rings can be tested. Thus, the potential materials combinations are endless. In addition, the test can be run with different gaseous atmospheres and elevated temperatures, as desired, to simulate service conditions. 1.3 Wear test results are reported as the volume loss in cubic millimetres for the block and ring. Materials of higher wear resistance will have lower volume loss. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with it...

  6. Standard test method for ranking resistance of materials to sliding wear using block-on-ring wear test

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This test method covers laboratory procedures for determining the resistance of materials to sliding wear. The test utilizes a block-on-ring friction and wear testing machine to rank pairs of materials according to their sliding wear characteristics under various conditions. 1.2 An important attribute of this test is that it is very flexible. Any material that can be fabricated into, or applied to, blocks and rings can be tested. Thus, the potential materials combinations are endless. However, the interlaboratory testing has been limited to metals. In addition, the test can be run with various lubricants, liquids, or gaseous atmospheres, as desired, to simulate service conditions. Rotational speed and load can also be varied to better correspond to service requirements. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. Wear test results are reported as the volume loss in cubic millimetres for both the block and ring. Materials...

  7. Effect of wearing fingers rings on the behavioral and psychological symptoms of dementia: An exploratory study

    Science.gov (United States)

    Yokoi, Teruo; Okamura, Hitoshi; Yamamoto, Tomoka; Watanabe, Katsuya; Yokoi, Shigeko; Atae, Hitoshi; Ueda, Masayuki; Kuwayama, Takahiro; Sakamoto, Shigekazu; Tomino, Saaya; Fujii, Hideo; Honda, Takefumi; Morita, Takayosi; Yukawa, Takafumi; Harada, Nobuko

    2017-01-01

    Objective: This study was conducted to examine the effects of an approach that wears finger rings on elderly females with behavioral and psychological symptoms of dementia. Method: The subjects were seven Japanese dementia patients living in elderly nursing homes. A single-case experimental design was adopted for the study. Each study subject was asked to put rings on her finger (from 9:00 to 19:00) for 7 days. The Neuropsychiatric Inventory, scenes of behavioral and psychological symptoms of dementia, interest in wearing rings, self-awareness, and overall profile were determined to assess the effect on the patients of wearing rings. Results: The majority of nursing care providers stated, based on their assessment, that the “irritability/lability” that was noted during the baseline period disappeared during the ring-wearing intervention period in the three patients who displayed an interest in rings. In the assessment of the self-awareness ability, these three women were aware themselves of their intellect collapsing and were capable of conjecturing their own and others’ minds. It was commonly seen that the nursing staff, even though they had not been asked to do so by the researchers, told the patients, “Mrs. XX, you look so beautiful” when they found a patient wearing rings. Discussion/conclusion: Individuals with low self-esteem are inclined to get angry and display aggression. In subjects with low self-esteem, anger and aggression readily arise when they are slighted by others. Self-esteem is low in those women who are aware of their own status of collapsing intellect. It is concluded that the words of conjuration, “you look so beautiful,” which the wearing of the ring per se by the patient elicited from the caregivers heightened the self-esteem and alleviated “irritability/lability” in the study subjects. PMID:28856006

  8. Investigation into Transient Flow in a Centrifugal Pump with Wear Ring Clearance Variation

    Directory of Open Access Journals (Sweden)

    Houlin Liu

    2014-04-01

    Full Text Available The leakage flow paths in the sidewall gaps of centrifugal pumps are of significant importance for numbers of effects. The paper is concerned with the transient flow in the leakage flow paths with wear ring clearance variation. For this purpose, numerical simulations of the whole pump were carried out. The grid dependence and yplus check were performed first. Additionally, experimental data of performance characteristic and pressure fluctuation inside the sidewall gap was used to validate the numerical results. The transient velocity fields inside the sidewall gaps during one blade passage period were simulated. And the leakage through the wear ring gap was obtained for all operating points investigated. To have a better idea of attenuation and propagation of pressure inside the sidewall gap, the unsteady pressure distributions in the gap were calculated. Additionally, the surfaces of the impeller were divided into four parts. The fluid force on each part was expressed as a percentage of the total radial force. Through comparing the flow fields, the pressure distributions, and the radial force between the pumps with different wear ring clearances, the effects of the wear ring clearance were discussed in detail. The results can be used to guide the optimum design of the pump sidewall gaps.

  9. Lubrication and Sealing Analysis of Diesel Engine Piston Ring Pack%柴油机活塞环组密封润滑分析

    Institute of Scientific and Technical Information of China (English)

    邓志明; 朱海庆; 张红涛

    2011-01-01

    良好的密封和润滑是活塞环长期稳定运行的保障。在气密性仿真分析的基础上,建立了活塞环组的贫油润滑模型,提出了一种新的边界条件求解润滑模型。利用MATLAB仿真程序,完成了PA6—280柴油机活塞环组的密封与贫油润滑分析。结果发现,在密封性能良好的条件下,活塞环组处于一种非稳态的混合润滑状态,并且各个活塞环的润滑受先导环的润滑油供给情况影响很大。%Good sealing and lubrication ensures the piston ring to run stably for a long period On basis of sealing simulation and analysis, a poor lubrication model of piston ring group was established, where a new boundary condition was proposed solve the model. With MATLAB simulation program, the Sealing and poor lubrication analysis of PA6 - 280 diesel piston ring group was completed. It is found that piston ring group is on an unsteady state of mixed lubrication when it is in good sealing. Besides, the lubrication of all rings were greatly affected by oil supply of the leading ring.

  10. Effect of Porosity on the Mechanical Properties and Wear Performance of 2% Copper Reinforced Sintered Steel Used in Shock Absorber Piston Production

    Institute of Scientific and Technical Information of China (English)

    Bekir Yal(c)in

    2009-01-01

    Powder metallurgy (P/M) method has mainly been used to produce automobile parts such as self-lubrication beds, shock absorber parts, and gear wheels. In order to investigate the effect of porosity on the mechanical and tribological properties in sintered steel, specimens with 10%, 15%, and 20% porosity were produced in a 10 mm×10 mm×55 mm prismatic shape by pre-alloying powders of the MPIF Fe-C-0.205 alloy used in the production of shock absorber pistons. Sintering was carried out at 900℃ for 45 min in an argon atmosphere. Tensile, charpy, and microhardness tests were performed on these specimens. In addition, the wear performance of a 2% Cu reinforced sintered steel alloy under dry sliding conditions was determined. Metallographic studies such as pore formation, worn surface, and fractured surface analyses were performed by scanning electron microscopy and optical microscopy. The results indicate that irregular pore formation tendencies increase with an increase in porosity (%). Furthermore, an increase in porosity was shown to decrease the mechanical properties and increase the wear trace area and the friction coefficient of sintered steel.

  11. Surface and Wear Analysis of Zinc Phosphate Coated Engine Oil Ring and Cylinder Liner Tested with Commercial Lubricant

    Directory of Open Access Journals (Sweden)

    Doğuş Özkan

    2014-09-01

    Full Text Available The objective of this study was to evaluate the tribological performance through investigating protective additive layer and friction coefficient and implementing the quantitative wear measurements on the rubbed surface of the sliding pairs. The specimens of oil ring were rubbed against cast iron engine cylinder liner under boundary lubrication conditions. The ring and liner surfaces were examined by optical, scanning electron microscope and atomic force microscopy. The elemental analysis of surfaces was performed by using energy dispersive X-ray spectroscopy. Surface observations showed that coating was removed from the ring surface. Higher levels of Ca, Zn, P, and S elemental ratios (0.93%, 0.45%, 1.55%, and 1.60% as atomic percent were detected on the cylinder liner surface. Wear width, length, and depth measurements were performed by optical and atomic force microscopies on the ring and cylinder liner surface. The results showed that wear widths for oil ring were 1.59 μm and 1.65 μm; wear widths for cylinder liner were 3.20 μm and 3.18 μm; wear depths for oil ring were 100 nm; and wear depths for cylinder liner were 482 nm. Wear data were taken mostly from the additive layer points detected by SEM and X-ray measurements.

  12. Quantitative two-dimensional measurement of oil-film thickness by laser-induced fluorescence in a piston-ring model experiment.

    Science.gov (United States)

    Wigger, Stefan; Füßer, Hans-Jürgen; Fuhrmann, Daniel; Schulz, Christof; Kaiser, Sebastian A

    2016-01-10

    This paper describes advances in using laser-induced fluorescence of dyes for imaging the thickness of oil films in a rotating ring tribometer with optical access, an experiment representing a sliding piston ring in an internal combustion engine. A method for quantitative imaging of the oil-film thickness is developed that overcomes the main challenge, the accurate calibration of the detected fluorescence signal for film thicknesses in the micrometer range. The influence of the background material and its surface roughness is examined, and a method for flat-field correction is introduced. Experiments in the tribometer show that the method yields quantitative, physically plausible results, visualizing features with submicrometer thickness.

  13. Development of wear resistant ceramic coatings for diesel engine components

    Energy Technology Data Exchange (ETDEWEB)

    Haselkorn, M.H. (Caterpillar, Inc., Peoria, IL (United States))

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at these more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.

  14. 往复式压缩机活塞环技改小结%Revamping Summary of the Reciprocating Compressor Piston Rings

    Institute of Scientific and Technical Information of China (English)

    辛双和

    2014-01-01

    针对 ZW-9/30型往复式压缩机活塞环频繁损坏、设备运行周期短的问题,分析其原因,提出相应的技改措施,保证压缩机的正常运行。%For problems of ZW‐9/30 reciprocating compressor piston rings frequent damage and the short running cycle of the equipment , analyze the causes , propose appropriate revamping measures to ensure the compressor normal operation .

  15. Pistons and engine testing

    CERN Document Server

    GmbH, Mahle

    2012-01-01

    The ever-increasing demands placed on combustion engines are just as great when it comes to this centerpiece - the piston. Achieving less weight or friction, or even greater wear resistance, requires in-depth knowledge of the processes taking place inside the engine, suitable materials, and appropriate design and machining processes for pistons, including the necessary testing measures. It is no longer possible for professionals in automotive engineering to manage without specific know-how of this kind, whether they work in the field of design, development, testing, or maintenance. This techni

  16. 提高活塞环耐磨性的激光强化新技术%New Laser-Strengthening Technologies for Improving Wearability of the Engine Piston Ring

    Institute of Scientific and Technical Information of China (English)

    陈奉斌; 花银群; 胡昌龄; 张永康; 毕瑞

    2001-01-01

    The new laser-strengthening technologies to improve the wearability of the engine piston ring are introduced from different aspects.The effect of laser quenching of the piston ring and the inside wall of the cylinder liner,and laser texturing of the cylinder liner on the wearability of the piston ring are discussed respectively.The experimental results show that each process can make the life of the piston ring increase by 100%.The laser texturing can not only make the piston ring life increase 100%,but also decrease fuel exhaustion by 30%~60% and discharge of HC gas by 10%~20%.%从多方面论述了提高发动机活塞环耐磨性的激光强化新技术,分别讨论了活塞环的激光淬火、气缸套内壁激光淬火,以及气缸套激光毛化对活塞环耐磨性的影响.结果表明,各自单独处理则都可提高活塞环寿命1倍以上.采用激光造形, 则不仅可提高活塞环的使用寿命1倍,而且降低机油消耗量30%~60%,降低HC排放量10%~20%.

  17. Wear mechanism and wear prevention in coal-fueled diesel engines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Schwalb, J.A.; Ryan, T.W.

    1991-10-01

    Coal fueled diesel engines present unique wear problems in the piston ring/cylinder liner area because of their tendency to contaminate the lube-oil with high concentrations of highly abrasive particles. This program involved a series of bench-scale wear tests and engine tests designed to investigate various aspects of the ring/liner wear problem and to make specific recommendations to engine manufacturers as to how to alleviate these problems. The program was organized into tasks, designed to accomplish the following objectives: (1) define the predominant wear mechanisms causing accelerated wear in the ring/liner area; (2) investigate the effectiveness of traditional approaches to wear prevention to prevent wear in coal-fueled engines; (3) further refine information on the most promising approaches to wear prevention; (4) present detailed information and recommendations to engine manufacturers on the most promising approach to wear prevention; (5) present a final report covering the entire program; (6)complete engine tests with a coal-derived liquid fuel, and investigate the effects of the fuel on engine wear and emissions.

  18. Wear mechanism and wear prevention in coal-fueled diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Schwalb, J.A.; Ryan, T.W.

    1991-10-01

    Coal fueled diesel engines present unique wear problems in the piston ring/cylinder liner area because of their tendency to contaminate the lube-oil with high concentrations of highly abrasive particles. This program involved a series of bench-scale wear tests and engine tests designed to investigate various aspects of the ring/liner wear problem and to make specific recommendations to engine manufacturers as to how to alleviate these problems. The program was organized into tasks, designed to accomplish the following objectives: (1) define the predominant wear mechanisms causing accelerated wear in the ring/liner area; (2) investigate the effectiveness of traditional approaches to wear prevention to prevent wear in coal-fueled engines; (3) further refine information on the most promising approaches to wear prevention; (4) present detailed information and recommendations to engine manufacturers on the most promising approach to wear prevention; (5) present a final report covering the entire program; (6)complete engine tests with a coal-derived liquid fuel, and investigate the effects of the fuel on engine wear and emissions.

  19. Pistons and engine testing

    CERN Document Server

    2016-01-01

    The ever-increasing demands placed on combustion engines are just as great when it comes to this centerpiece—the piston. Achieving less weight or friction, or even greater wear resistance, requires in-depth knowledge of the processes taking place inside the engine, suitable materials, and appropriate design and manufacturing processes for pistons, including the necessary testing measures. It is no longer possible for professionals in automotive engineering to manage without specific expertise of this kind, whether they work in the field of design, development, testing, or maintenance. This technical book answers these questions in detail and in a very clear and comprehensible way. In this second, revised edition, every chapter has been revised and expanded. The chapter on “Engine testing”, for example, now include extensive results in the area of friction power loss measurement and lube oil consumption measurement. Contents Piston function, requirements, and types Design guidelines Simulation of the ope...

  20. Development of wear resistant ceramic coatings for diesel engine components. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Haselkorn, M.H. [Caterpillar, Inc., Peoria, IL (United States)

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at these more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.

  1. The Friction and Wear of Active Lubricants in theSleeve-ring Pair Lubricated by Presence of Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    ZHOUQiang; LIJian-ping; LONGHong-sheng

    2004-01-01

    The effect of magnetic fteld on the tribological process of sleeve-ring pair lubricated by WRL lu-bricants was investigated by means of a NG-x wear tester and a PS5013 video microscope. The friction coefficient (f) and the wear weight(W) in lubricating test with WRL lubricant were decreased with the increase in the ,mag-netic field vertical to the rubbing surface, and an almost zero wear lubricating situation was gained in a magneticfield of 1000A/m. The captured wear micro particles on the rubbing surface were observed in the testing process,and the theoretical analysis of magnetic effects was completed. It is indicated that the magnetic field has not only a capturing action of wear micro particles on the worn surface, but also a inducing polarization0 of magnetic anisotropy of lubricant molecular. The actions promote the absorption of WRL lubricant into the wear swrface aswell as wear micro-particles, so that a good tribological effect is obtained when both magnetic field and WRL pr-esent.

  2. Wear mechanism and wear prevention in coal-fueled diesel engines. Task 3, Traditional approaches to wear prevention

    Energy Technology Data Exchange (ETDEWEB)

    Schwalb, J.A.

    1991-06-01

    Contamination of the lube-oil with hard abrasive particles leads to a three-body abrasive wear mechanism that highly accelerates piston ring/cylinder liner wear in coal-fueled diesel engines. One approach to reducing that wear is to modify the size and orientation of surface asperities on the cylinder to enhance the formation of a hydrodynamic film, and to provide avenues of escape for particles that would otherwise be trapped in the wear zone. Another approach is to introduce additives into the contaminated lube-oil that further enhance hydrodynamic film formation, form chemical films on the wearing surfaces, or form films on the contaminant particles. This work focuses on defining the effects of cylinder liner surface finish, various configurations of slots in the cylinder liner surface, and various additives in the contaminated lube-oil on the wear process. Wear tests were initiated in a bench apparatus using coal-ash contaminated lube-oil to test the various wear configurations. The results of these tests indicate that the formation of a hydrodynamic film between the ring and cylinder specimens is enhanced by increasing surface roughness, and by orienting the surface asperities normal to the direction of ring travel but modifications to the cylinder liner surface did not greatly reduce the wear rate. Additives to the lubricant seemed to have a much more significant effect on wear, with a dispersant additive highly accelerating the wear, while a detergent additive was able to reduce the wear almost to the rate achieved where there was no contaminant.

  3. Wear mechanism and wear prevention in coal-fueled diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Schwalb, J.A.

    1991-06-01

    Contamination of the lube-oil with hard abrasive particles leads to a three-body abrasive wear mechanism that highly accelerates piston ring/cylinder liner wear in coal-fueled diesel engines. One approach to reducing that wear is to modify the size and orientation of surface asperities on the cylinder to enhance the formation of a hydrodynamic film, and to provide avenues of escape for particles that would otherwise be trapped in the wear zone. Another approach is to introduce additives into the contaminated lube-oil that further enhance hydrodynamic film formation, form chemical films on the wearing surfaces, or form films on the contaminant particles. This work focuses on defining the effects of cylinder liner surface finish, various configurations of slots in the cylinder liner surface, and various additives in the contaminated lube-oil on the wear process. Wear tests were initiated in a bench apparatus using coal-ash contaminated lube-oil to test the various wear configurations. The results of these tests indicate that the formation of a hydrodynamic film between the ring and cylinder specimens is enhanced by increasing surface roughness, and by orienting the surface asperities normal to the direction of ring travel but modifications to the cylinder liner surface did not greatly reduce the wear rate. Additives to the lubricant seemed to have a much more significant effect on wear, with a dispersant additive highly accelerating the wear, while a detergent additive was able to reduce the wear almost to the rate achieved where there was no contaminant.

  4. Entropy-Based weighting applied to normal boundary intersection approach: the vertical turning of martensitic gray cast iron piston rings case

    Directory of Open Access Journals (Sweden)

    Luiz Célio Souza Rocha

    2015-10-01

    Full Text Available In practical situations, solving a given problem usually calls for the systematic and simultaneous analysis of more than one objective function. Hence, a worthwhile research question may be posed thus: In multiobjective optimization, what can facilitate the decision maker in choosing the best weighting? Thus, this study attempts to propose a method that can identify the optimal weights involved in a multiobjective formulation. Our method uses functions of Entropy and Global Percentage Error as selection criteria of optimal weights. To demonstrate its applicability, we employed this method to optimize the machining process for vertical turning martensitic gray cast iron piston rings, maximizing the productivity and the life of cutting tool and minimizing the cost, using feed rate and rotation of the cutting tool as the decision variables. The proposed optimization goals were achieved with feed rate = 0.35 mm rev-1 and rotation = 248 rpm. Thus, the main contributions of this study are the proposal of a structured method, differentiated in relation to the techniques found in the literature, of identifying optimal weights for multiobjective problems and the possibility of viewing the optimal result on the Pareto frontier of the problem. This viewing possibility is very relevant information for managing processes more efficiently.

  5. Wear mechanism analysis of ring die of pellet mill%生物质制粒机环模的磨损机理分析

    Institute of Scientific and Technical Information of China (English)

    蒋清海; 武凯; 孙宇; 夏先飞

    2013-01-01

    A Rotating ring die pellet mill has been widely used in the feed, renewable biomass, and pharmaceutical industries, for its strengths such as high production efficiency, low transportation cost, and low energy consumption. A ring die is the core part of a pellet mill. At present, the granulating technology was seriously restricted due to the quick abrasion and short service life of the ring die. The purpose of this study was to provide a basis for improving the wear resistance and extending the working life of a ring die by wear mechanism analysis. In this paper, the working process of a pellet mill was studied, the distribution and change rule of the force state of a ring die were analyzed. A wear experiment of a ring die that was manufactured by a steel X46Cr13 with a quenching and tempering treatment was carried out under the practical production condition for 600 hours, the hardening depth was 3 mm, and the surface morphology was observed first. The abrasion depth of the ring die wall and the hole wall was measured by using a LK-G10 laser displacement sensor, the hardness of the wearing surface was measured with a HR-1500DT electric Rockwell apparatus, and the microscopic wear morphology of the wearing surface was observed by a JSM-6300 scanning electron microscope (SEM). The distribution of the abrasion and the wear mechanism of the wearing surface were studied from both macroscopic and microscopic aspects. The research results showed that the wear mechanisms of a ring die include polishing wear, abrasive wear, and fatigue wear, and different wear mechanisms play a leading role in different wear positions. The ring die wall was seriously abraded, the wear depth was around 3 mm and up to 3.4 mm was closed to the feeding side. With the depletion of the hardened layer, the hardness of the ring die wall descends slightly. The wear mechanisms of a ring die wall are fatigue wear and abrasive wear that is featured mainly as micro cutting. The material loss of a ring

  6. Dynamics of crank-piston mechanisms

    CERN Document Server

    Davitashvili, Nodar

    2016-01-01

    This monograph focuses on the dynamical research work on crank-piston mechanisms considering basic and additional motions. In order to have full dynamical analyses of piston machines and their mechanisms, the book studies the crank-piston mechanisms with clearances in kinematic pairs. The tasks are carried out by focusing on friction, wear and impacts in mechanisms, as well as cracks formation in links and elasticity of details, with distributed and concentrated masses. Then, the reliability and durability of the mechanisms of piston machines is applied on oil and gas transportation. The monograph is meant for design specialists. It is also useful for specialists-manufacturers and designers of piston machines, scientists and lecturers, doctoral students.

  7. Sources of tooth wear variation early in life among known-aged wild ring-tailed lemurs (Lemur catta) at the Bezà Mahafaly Special Reserve, Madagascar.

    Science.gov (United States)

    Cuozzo, Frank P; Head, Brian R; Sauther, Michelle L; Ungar, Peter S; O'Mara, M Teague

    2014-11-01

    Ring-tailed lemurs (Lemur catta) at the Bezà Mahafaly Special Reserve (BMSR), Madagascar display a high frequency of individuals with notable and sometimes extreme tooth wear. Adult lemurs display a range of tooth wear even among individuals of the same age, but we do not know at what age this variation first appears. This study's goal was to determine whether wear variation occurs in younger wild lemurs. Based on the decade-long study of ring-tailed lemur feeding and dental ecology at BMSR, we hypothesized that younger, natal lemurs (under 5 years of age), would display variation in their degree of tooth wear that would correspond to microhabitat differences, given differences in food availability in different troops' home ranges. We also hypothesized that wear would differ between sexes at this young age, given differences in feeding between males and females in this population. Hypotheses were tested using dental topographic analyses using dental impressions collected from known-aged lemurs across 10 years at BMSR. Results illustrate significant differences in wear-related tooth topography (i.e., relief and slope, presented here as "occlusal lift") for microhabitat, sex and troop affiliation among lemurs under 5 years of age in this population. Although, all lemurs in this population consume mechanically challenging tamarind fruit, those in more disturbed habitats eat additional introduced foods, some of which are also mechanically challenging. Thus, dietary variation is the likely cause of variation in tooth wear. The wear variation we show at a young age suggests caution when assigning age based on tooth wear in living and fossil primates. These wear-related tooth shape changes early in life, which reflects sex, habitat variation and levels of anthropogenic disturbance, may potentially impact reproductive fitness later in life. © 2014 Wiley Periodicals, Inc.

  8. REDUCED ENGINE FRICTION AND WEAR

    Energy Technology Data Exchange (ETDEWEB)

    Ron Matthews

    2005-05-01

    This Final Technical Report discusses the progress was made on the experimental and numerical tasks over the duration of this project regarding a new technique for decreasing engine friction and wear via liner rotation. The experimental subtasks involved quantifying the reduction in engine friction for a prototype rotating liner engine relative to a comparable baseline engine. Both engine were single cylinder conversions of nominally identical production four-cylinder engines. Hot motoring tests were conducted initially and revealed that liner rotation decreased engine friction by 20% under motoring conditions. A well-established model was used to estimate that liner rotation should decrease the friction of a four-cylinder engine by 40% under hot motoring conditions. Hot motoring tear-down tests revealed that the crankshaft and valve train frictional losses were essentially the same for the two engines, as expected. However, the rotating liner engine had much lower (>70%) piston assembly friction compared to the conventional engine. Finally, we used the Instantaneous IMEP method to compare the crank-angle resolved piston assembly friction for the two engines. Under hot motoring conditions, these measurements revealed a significant reduction in piston assembly friction, especially in the vicinity of compression TDC when the lubrication regime transitions from hydrodynamic through mixed and into boundary friction. We have some remaining problems with these measurements that we expect to solve during the next few weeks. We will then perform these measurements under firing conditions. We also proposed to improve the state-of-the-art of numerical modeling of piston assembly friction for conventional engines and then to extend this model to rotating liner engines. Our research team first modeled a single ring in the Purdue ring-liner test rig. Our model showed good agreement with the test rig data for a range of speeds and loads. We then modeled a complete piston

  9. Piston rod seal for a Stirling engine

    Science.gov (United States)

    Shapiro, Wilbur

    1984-01-01

    In a piston rod seal for a Stirling engine, a hydrostatic bearing and differential pressure regulating valve are utilized to provide for a low pressure differential across a rubbing seal between the hydrogen and oil so as to reduce wear on the seal.

  10. Variation in dental wear and tooth loss among known-aged, older ring-tailed lemurs (Lemur catta): a comparison between wild and captive individuals.

    Science.gov (United States)

    Cuozzo, Frank P; Sauther, Michelle L; Gould, Lisa; Sussman, Robert W; Villers, Lynne M; Lent, Cheryl

    2010-11-01

    Tooth wear is generally an age-related phenomenon, often assumed to occur at similar rates within populations of primates and other mammals, and has been suggested as a correlate of reduced offspring survival among wild lemurs. Few long-term wild studies have combined detailed study of primate behavior and ecology with dental analyses. Here, we present data on dental wear and tooth loss in older (>10 years old) wild and captive ring-tailed lemurs (Lemur catta). Among older ring-tailed lemurs at the Beza Mahafaly Special Reserve (BMSR), Madagascar (n=6), the percentage of severe dental wear and tooth loss ranges from 6 to 50%. Among these six individuals, the oldest (19 years old) exhibits the second lowest frequency of tooth loss (14%). The majority of captive lemurs at the Indianapolis Zoo (n=7) are older than the oldest BMSR lemur, yet display significantly less overall tooth wear for 19 of 36 tooth positions, with only two individuals exhibiting antemortem tooth loss. Among the captive lemurs, only one lemur (a nearly 29 year old male) has lost more than one tooth. This individual is only missing anterior teeth, in contrast to lemurs at BMSR, where the majority of lost teeth are postcanine teeth associated with processing specific fallback foods. Postcanine teeth also show significantly more overall wear at BMSR than in the captive sample. At BMSR, degree of severe wear and tooth loss varies in same aged, older individuals, likely reflecting differences in microhabitat, and thus the availability and use of different foods. This pattern becomes apparent before "old age," as seen in individuals as young as 7 years. Among the four "older" female lemurs at BMSR, severe wear and/or tooth loss do not predict offspring survival. © 2010 Wiley-Liss, Inc.

  11. Wear resistance of a metal surface modified with minerals

    Science.gov (United States)

    Kislov, S. V.; Kislov, V. G.; Balasch, P. V.; Skazochkin, A. V.; Bondarenko, G. G.; Tikhonov, A. N.

    2016-02-01

    The article describes the advantages of the new technology of mineral coating of metal products for the friction pair of mechanical systems. It presents the research results of the wear rate of the samples made of 12X13 steel (X12Cr13) with mineral layers, in the experiments with a piston ring sliding inside a cylinder liner with grease. The wear rate of the samples with mineral layers is lower almost by two factors than that of the samples made of grey foundry iron and untreated samples. As the result of slip/rolling abrasion tests of parts with mineral layers under conditions of high contact pressure, a suggestion was made concerning probable mechanics of surface wear.

  12. Design Analysis and Optimization of Internal Combustion Engine Piston using CAE tool ANSYS

    Directory of Open Access Journals (Sweden)

    Aditya Kumar Gupta

    2014-11-01

    Full Text Available In the internal combustion engine there are many reciprocating parts which are responsible for giving the motion to the engine. from them the piston is very important part of the internal combustion engine.. The working condition of the piston is so worst in comparison of other parts of the internal combustion engine. There is very high probability to failure of the piston due to high wear and tear. So there is necessary to inspection the working condition of piston. In before there is no availability of software packages. So there is difficult to check out the failure of the piston, it is also very time taken process. In now days the software packages are used to consume less time and give quality assurance. In this study work there are two steps of analysis of the piston they are Designing and Analysis. Firstly design the model of the piston in giving design specification on the modelling software like INVENTOR . Then giving it the constraints which are act on the working condition of the piston after import the model of the piston into the analysis software ANSYS in IGES format. Then the analysis become completed on the different parameters(temperature, stress, deformation and easily analysis the result. In this work the piston become optimized after the reducing the material of the piston. the mass and volume of the piston become reduced. The deformation also increased after the optimization which is responsible for the stress distribution on the piston head or piston crown.

  13. Less wear and oil consumption through helical slide honing of engines by Deutz; Weniger Verschleiss und Oelverbrauch durch Spiralgleithonung bei Deutz-Motoren

    Energy Technology Data Exchange (ETDEWEB)

    Hoen, Thomas [DEUTZ AG, Koeln (Germany); Schmid, Josef [Nagel Maschinen- und Werkzeugfabrik GmbH, Nuertingen (Germany); Stumpf, Walter [Federal Mogul, Burscheid (Germany)

    2009-04-15

    Within the scope of continuous development for the Deutz 2012 engines (4 l and 6 l engines) and Tier 3 emissions standards, new developments are required with regard to achieving a new maximum power requirement of 178 kW at 2100 rpm and a higher EGR rate via cooled exhaust gas recirculation. Without implementing engine design changes, the new Tier III constraints are expected to lead to higher wear in the cylinder unit (cylinder bore, piston, piston rings). Together with Deutz, Nagel found a solution for the expected cylinder unit wear on the existing engine, which not only eliminates the potential future wear problem, but also contributes to the important economic considerations of oil consumption and maintenance intervals. (orig.)

  14. Wear mechanism of ring die for straw briquetting machine%秸秆压块机组合环模的磨损机理

    Institute of Scientific and Technical Information of China (English)

    夏先飞; 孙宇; 武凯; 蒋清海

    2014-01-01

    As one of the important biomass resources in China, straw plays an important role in energy utilization. While straw solidifying technology provides an effective utilization route which has been widely used. After densification, both density and intensity of the straw fuel were improved, making it easier to transport, store and use. And this efficient utilization is also crucial for providing bio-energy, releasing the risk of environmental pollution caused by crop straw burning. But there are still some problems, such as easy wear of ring die, which will shorten its service life. In this paper, the wear behavior of ring die has been studied based on experimental test and theoretical analysis. After the shape of the worn ring die was tested, the microscopy morphology was obtained by scanning electron microscopy (SEM), and then the wear mechanism was analyzed. By testing it is found that abrasion mainly occurs in the middle part and lower side of the die, and abrasion gradually weakens along the feed direction. Hard abrasive wear plays a leading role in the wear process;the material loss of the die surface is caused by the cutting fracture mechanism. According to conclusions above, the calculation model of this abrasive wear was deduced based on fractal theory. It shows that the wear rate of the ring die is related to the particle size silhouette coefficient G, contact area Ar, forming speed v and material properties. Then the effect of the forming speed and the hardness of the ring die to this abrasive wear was investigated by using finite element analysis software DEFORM. The forming speed was set as 7, 8, 9 and 10 mm/s four levels, and the die hardness was set as 42.5, 45, 47.5 and 50 HRC four levels. The forming temperature was 110℃ while the extruded material length was 45 mm. Simulation results show that the wear depth of the ring die increases with increasing forming speed and decreases with increasing die hardness. Range analysis results of the above two

  15. A Review of Sub-Scale Test Methods to Evaluate the Friction and Wear of Ring and Liner Materials for Spark- and Compression Ignition Engines

    Energy Technology Data Exchange (ETDEWEB)

    Blau, P.J.

    2002-01-22

    A review was conducted of past laboratory-scale test methods and to assess their validity for ranking materials and lubricants for use as piston and liner materials in compression-ignition (CI) and spark-ignition (SI) engines. Most of the previous work was aimed at simulating SI engine environments. This report begins with a discussion of the numerous factors that can affect the validity of an approach to simulating engine conditions in a laboratory. These include not only mechanical, chemical and thermal factors, but also human factors as regards how the vehicle is operated and maintained. The next section provides an annotated review of open literature publications that address the issues of laboratory simulation of engine components. A comparison of these studies indicates a lack of sufficient standardization in procedures to enable a systematic comparison of one publication to another. There were just a few studies that compared several laboratory test methods to engine test results, and these indicated that some test methods correlate, at least qualitatively, better than others. The last section provides a series of recommendations for improving the accuracy and validity of laboratory-scale simulations of engine behavior. It became clear that much of the engine wear damage occurs during start-up when the engine is cold, and this calls into the question the usefulness of test methods that attempt to simulate steady-state running conditions. It is recommended that a new standard test method, perhaps developed with the help of the ASTM wear and erosion committee, be developed. It would use cold start-up conditions in the presence of degraded oil, or simulated degraded oil.

  16. The development and testing of ceramic components in piston engines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    McEntire, B.J. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.; Willis, R.W.; Southam, R.E. [TRW, Inc., Cleveland, OH (United States)

    1994-10-01

    Within the past 10--15 years, ceramic hardware has been fabricated and tested in a number of piston engine applications including valves, piston pins, roller followers, tappet shims, and other wear components. It has been shown that, with proper design and installation, ceramics improve performance, fuel economy, and wear and corrosion resistance. These results have been obtained using rig and road tests on both stock and race engines. Selected summaries of these tests are presented in this review paper.

  17. The problems of piston skirt microgeometry in combustion engines

    Science.gov (United States)

    Iskra, A.; Babiak, M.; Wróblewski, E.

    2016-09-01

    Geometry of the slot between piston bearing surface and cylinder bore affects the friction losses of the IC engine to the far extent. It appears that these losses depend more on the area covered with oil than the thickness of oil layer separating collaborating parts. Barrel-shaped or stepwise piston bearing surface is the way to reduce the oil covered area. Turns out that the referred to friction losses contributes more to area covered by the oil film than the film thickness of the separation elements cooperating. The method to reduce the area covered by the oil film is a modification of the bearing surface of the piston by adjusting the profile. This paper presents the results of simulation leading to the reduction in friction losses and abrasive wear of piston bearing surface and cylinder bore. Covering the piston bearing surface with a thin layer of graphite one can get an extremely advantageous tribological properties of the piston assembly which means the expected parameters of oil film and in a case of film rupture-an ignorable abrasive wear of the graphite layer and/or cylinder bore.

  18. Rotary-piston internal combustion engine. Rotationskolbenbrennkraftmaschine

    Energy Technology Data Exchange (ETDEWEB)

    Eiermann, D.

    1991-08-08

    Rotary-piston internal combustion engine in trochoidal design with a slide bearing piston which is controlled by a synchronous gear. The gear is covered by an insert unit which is screwed at the eccentric. The insert unit seals the synchronous gear from the remaining machine parts; it has a hollow cylinder which covers the hollow gear of the synchronous gear and is eccentric to the eccentric shaft; it is sealed with a sealing ring from a shoulder of the piston. A further hollow cylinder is coaxial to the eccentric shaft; it surrounds the mount part with a clearance for the pinion; it projects into the boring at the side of the shaft and it is sealed by a sealing ring from the boring. An annular space which is sealed from the remaining engine rooms is on the other side of the bearing. The oil which escapes from the bearing is led from this annular space through the cooling rooms of the piston to the synchronous gear. The oil is carried off into a drain channel through the space which is formed by the coaxial hollow cylinder in the sidewall.

  19. Experimental Thermal Analysis of Diesel Engine Piston and Cylinder Wall

    Directory of Open Access Journals (Sweden)

    Subodh Kumar Sharma

    2015-01-01

    Full Text Available Knowledge of piston and cylinder wall temperature is necessary to estimate the thermal stresses at different points; this gives an idea to the designer to take care of weaker cross section area. Along with that, this temperature also allows the calculation of heat losses through piston and cylinder wall. The proposed methodology has been successfully applied to a water-cooled four-stroke direct-injection diesel engine and it allows the estimation of the piston and cylinder wall temperature. The methodology described here combines numerical simulations based on FEM models and experimental procedures based on the use of thermocouples. Purposes of this investigation are to measure the distortion in the piston, temperature, and radial thermal stresses after thermal loading. To check the validity of the heat transfer model, measure the temperature through direct measurement using thermocouple wire at several points on the piston and cylinder wall. In order to prevent thermocouple wire entanglement, a suitable pathway was designed. Appropriate averaged thermal boundary conditions such as heat transfer coefficients were set on different surfaces for FE model. The study includes the effects of the thermal conductivity of the material of piston, piston rings, and combustion chamber wall. Results show variation of temperature, stresses, and deformation at various points on the piston.

  20. Analysis of Piston Slap Motion

    Directory of Open Access Journals (Sweden)

    Narayan S.

    2015-05-01

    Full Text Available Piston slap is the major force contibuting towards noise levels in combustion engines.This type of noise depends upon a number of factors such as the piston-liner gap, type of lubricant used, number of piston pins as well as geometry of the piston. In this work the lateral and rotary motion of the piston in the gap between the cylinder liner and piston has been analyzed. A model that can predict the forces and response of the engine block due to slap has been dicussed. The parameters such as mass, spring and damping constant have been predicted using a vibrational mobility model.

  1. Analysis of Piston Slap Motion

    Science.gov (United States)

    Narayan, S.

    2015-05-01

    Piston slap is the major force contibuting towards noise levels in combustion engines.This type of noise depends upon a number of factors such as the piston-liner gap, type of lubricant used, number of piston pins as well as geometry of the piston. In this work the lateral and rotary motion of the piston in the gap between the cylinder liner and piston has been analyzed. A model that can predict the forces and response of the engine block due to slap has been dicussed. The parameters such as mass, spring and damping constant have been predicted using a vibrational mobility model.

  2. 基于格子波兹曼方法研究颗粒对缸套-活塞环油膜压力的影响%Influences of solid particles on oil film pressure in cylinder-piston ring based on lattice-Boltzmann method

    Institute of Scientific and Technical Information of China (English)

    韩海燕; 张优云; 王凯

    2016-01-01

    Most liquid lubricating systems are inevitably supplied with lubricant containing contaminant particles. It is certain that some of these particles are suspended in the oil, that is, the size of the solid particle is smaller than the oil film thickness. In this paper, the effects of the suspended particles on the oil film pressure of cylinder-piston ring were mainly studied. In recent years, the lattice Boltzmann method (LBM) has been developed as an alternative to the conventional CFD (Computational Fluid Dynamics) methods. Unlike conventional numerical schemes based on discretization of macroscopic equations, the LBM is based on the statistical physics and describes the microscopic picture of particles movement in an extremely simplified way, but at the macroscopic level it gives a correct average description of the motion. It has been widely used to simulate the two-phase flow. The paper is aimed to study the influence of solid particles on the oil film pressure of piston ring based on L. The lubricate oil with suspended particles was regarded as the two-phase flow. The movement of the lubricate oil with solid particles is described with kinetic equations of distribution function of particles. A discrete Lattice-Boltzmann model of cylinder-piston ring was built in the domain of piston ring lubrication from the perspective of flow field. The implementation of boundary conditions for LBM is very important and has great effect on the accuracy and the stability of method. The bounce-back scheme was used in fluid-solid boundary and wall boundary treatment. The Reynolds boundary condition in the Lattice-Boltzmann Method was developed for the cracked oil film. By programming simulation, the influence of solid particles on the oil film pressure of piston ring was studied by researching the flow of the lubricant with solid particles based on LBM. The effect of particle location, shape and number on the oil film pressure of piston ring at certain crank angle was analyzed

  3. Analysis of Variation of Piston Temperature with Piston Dimensions and Undercrown Cooling

    Science.gov (United States)

    Sanders, J C; Schramm, W B

    1948-01-01

    A theoretical analysis is presented that permits estimation of the changes in piston-temperature distribution induced by variations in the crown thickness, the ring-groove-pad thickness, and the undercrown surface heat-transfer coefficient. The analysis consists of the calculation of operating temperatures at various points in the piston body on the basis of the experimentally determined surface heat-transfer coefficients and boundary-region temperatures, as well as arbitrarily selected surface coefficients. Surface heat-transfer coefficients were estimated from the internal temperature gradients obtained by hardness surveys of aluminum pistons that had been operated under severe conditions in a liquid-cooled, single-cylinder, 5 1/2 by 6-inch test engine.

  4. Orthogonal Experiments on Piston Skirt With Groove Structure%带有凹槽结构活塞裙部的正交试验

    Institute of Scientific and Technical Information of China (English)

    吴波; 熙鹏

    2014-01-01

    针对发动机活塞失效形式,结合活塞工作过程中所受应力的非均匀分布,以 XL-2V 型发动机为试验对象,将均匀排布的减阻耐磨型凹槽、凹坑结构优化变形为非均匀排布形式应用于活塞裙部。为了保证凹槽和通孔卸载活塞环槽集中应力作用的实现,同时使凹槽和通孔不影响活塞裙刚度以加大活塞裙底部变形,在发动机活塞裙部表面以环形形式逐行加工出变深度、变宽度、变间距的宏观凹槽及通孔形态,且槽深、槽宽、槽间距距离活塞顶部越近尺寸越大。运用正交试验方法制定了9种试验方案,选取3因素分别为孔槽分布类型、凹槽深度和凹槽宽度。搭建发动机冷试验台架,对9种凹槽形活塞和标准活塞进行对比试验,以磨损量和功率损耗率为试验结果指标。试验结果表明:凹槽形活塞磨损量平均减少35%、功率最大提高1%;凹槽形分布较其他2种分布类型减阻、耐磨效果更佳;较小的凹槽深宽设计更有助于保证活塞刚度、延长活塞寿命。%XL-2V type engine is used as the research subject. Failure modes of the engine piston and the stress of the working piston that is non-uniform distribution are considered. Many scientists developed the grooves and pits on the surface of kinematic pair, which were uniform distribution and friction reduction and wear-resisting. This paper optimizes the structures of grooves and pits, which are non-uniform distribution, for acclimatizing movement of engine piston. Grooves and through-holes surrounding the piston skirt of the engine is machined, which have variable-depth variable-width variable-separation. The sizes of depth, width and separation are bigger and closer to the top of piston to unload concentrated stress of piston ring grooves and keeping stiffness of piston skirt not to make enlargement deformation. With the orthogonal experiment method, nine test plans are made. The

  5. Electromagnetic liquid pistons for capillarity-based pumping.

    Science.gov (United States)

    Malouin, Bernard A; Vogel, Michael J; Olles, Joseph D; Cheng, Lili; Hirsa, Amir H

    2011-02-07

    The small scales associated with lab-on-a-chip technologies lend themselves well to capillarity-dominated phenomena. We demonstrate a new capillarity-dominated system where two adjoining ferrofluid droplets can behave as an electronically-controlled oscillator or switch by an appropriate balance of magnetic, capillary, and inertial forces. Their oscillatory motion can be exploited to displace a surrounding liquid (akin to an axial piston pump), forming electromagnetic "liquid pistons." Such ferrofluid pistons can pump a precise volume of liquid via finely tunable amplitudes (cf. pump stroke) or resonant frequencies (cf. pump speed) with no solid moving parts for long-term operation without wear in a small device. Furthermore, the rapid propagation of electromagnetic fields and the favorable scaling of capillary forces with size permit micron sized devices with very fast operating speeds (∼kHz). The pumping dynamics and performance of these liquid pistons is explored, with experimental measurements showing good agreement with a spherical cap model. While these liquid pistons may find numerous applications in micro- and mesoscale fluidic devices (e.g., remotely activated drug delivery), here we demonstrate the use of these liquid pistons in capillarity-dominated systems for chip-level, fast-acting adaptive liquid lenses with nearly perfect spherical interfaces.

  6. Numerical Simulation of Piston Ring Lubrication

    DEFF Research Database (Denmark)

    Felter, Christian Lotz

    2006-01-01

    variables u, v, rho for the velocity components and density, respectively. Time integration is performed by a third order Runge-Kutta method. The set of equations is closed by the Dowson- Higginson equation for the relation between density and pressure. Boundary conditions are the non-slip condition...

  7. A Study of Piston-Ring Friction

    Science.gov (United States)

    1947-08-01

    were caught by the upper oil seal. wc-5 TÄHUe II.- IBICECO SKOOKDB [Cylinder, SÄK 4l40f all Kings, Cast Iron] Fil» EDglDO Bpeei (npn) Braks ...HOLD PROCESS NO. 625-1-90-10 f« FINISH ’•flPAIÜr.L v-X 7^AP£BfflL& MUST BLEND V/’//i SMOOTHLY WITH OP- HONE ^M, -^QX^-QHAW

  8. OIL SLUGS FOR PRODUCTION OF PISTON RING

    Directory of Open Access Journals (Sweden)

    V. F. Bevza

    2008-01-01

    Full Text Available The developed technological process of continuously cyclic casting by frosting allows to receive high-quality hollow cylindrical slugs of cast iron for production of critical parts. 

  9. Compiling Method for Wear Spectrum of Engine Cylinder Liner%发动机气缸套磨损谱编制方法研究

    Institute of Scientific and Technical Information of China (English)

    司东亚; 骆清国; 许晋豪; 尹洪涛; 宁兴兴

    2015-01-01

    Based on the lubrication analysis between cylinder liner and piston ring ,the asperity load and wear rate of piston ring at different crank angles were calculated .The Archard wear calculation model was modified according to the dynamic load characteristics ,the engine operating conditions were discretized according to the load classification and the wear parameters of each discrete mesh were acquired .Based on the engine load spectrum ,the cylinder liner wear spectrum under typical mission profile was compiled using the time interpolation method .%通过对气缸套-活塞环进行润滑分析 ,得到了不同曲轴转角位置活塞环的微凸体载荷分布及磨损速率.结合动载荷特点对A rchard磨损计算模型进行了修正 ,同时根据载荷分级对发动机工况进行了离散 ,计算得到了各离散网格单元内的磨损参数 ,基于发动机整机载荷谱 ,采用时间插值方法 ,编制了典型任务剖面下的气缸套磨损谱.

  10. Bearing and gearing systems for rotary piston engines. Lager- und Getriebeanordnung einer Rotationskolbenmaschine

    Energy Technology Data Exchange (ETDEWEB)

    Eiermann, D.

    1991-03-14

    The proposed bearing and gearing system for rotary piston engines is provided with a trochoidal liner and triangular piston which is controlled by a synchromesh gear consisting of ring gear and pinion. The ring gear toothing is worked from the piston bore by shaping or broaching a depth of teeth which corresponds to the depth of the bore. A second, concentric bore inside the piston bore reaches from off the synchromesh gear to the ring gear and truncates the toothing of the latter. The stubs which are left hold the shell of the eccentric bearing. Cooling ducts are formed by the spaces in between. Since the bearing shell rests on the tooth stubs alone, the heat transfer from piston to eccentric bearing is considerably reduced.

  11. Internal combustion piston engines

    Energy Technology Data Exchange (ETDEWEB)

    Segaser, C.L.

    1977-07-01

    Current worldwide production of internal combustion piston engines includes many diversified types of designs and a very broad range of sizes. Engine sizes range from a few horsepower in small mobile units to over 40,000 brake horsepower in large stationary and marine units. The key characteristics of internal combustion piston engines considered appropriate for use as prime movers in Integrated Community Energy Systems (ICES) are evaluated. The categories of engines considered include spark-ignition gas engines, compression-ignition oil (diesel) engines, and dual-fuel engines. The engines are evaluated with respect to full-load and part-load performance characteristics, reliability, environmental concerns, estimated 1976 cost data, and current and future status of development. The largest internal combustion piston engines manufactured in the United States range up to 13,540 rated brake horsepower. Future development efforts are anticipated to result in a 20 to 25% increase in brake horsepower without increase in or loss of weight, economy, reliability, or life expectancy, predicated on a simple extension of current development trends.

  12. A Piston-Rotaxane with Two Potential Stripes: Force Transitions and Yield Stresses

    Directory of Open Access Journals (Sweden)

    Edith M. Sevick

    2013-10-01

    Full Text Available We examine a rod piston-rotaxane system, where the positions of several mobile rings on the axle are controlled by an external force acting on one of the rings. This allows us to access the translational entropy of the rings. For a simple rotaxane molecule with an axle that has uniform ring-axle interactions along its length, the molecule behaves like a miniature piston filled with a one-dimensional ideal gas. We then examine the effect of two stripes on the axle, having different ring-axle interactions with the mobile rings, so that one section is of high energy (repulsive for the rings and another section is of lower energy (or attractive. This kind of rotaxane can exhibit rapid changes in displacement or force, and in particular, this molecule can exhibit a yield stress in which the piston suddenly compresses under a small increase in the applied force.

  13. Interring Gas Dynamic Analysis of Piston in a Diesel Engine considering the Thermal Effect

    Directory of Open Access Journals (Sweden)

    Wanyou Li

    2015-01-01

    Full Text Available Understanding the interaction between ring dynamics and gas transport in ring pack systems is crucial and needs to be imperatively studied. The present work features detailed interring gas dynamics of piston ring pack behavior in internal combustion engines. The model is developed for a ring pack with four rings. The dynamics of ring pack are simulated. Due to the fact that small changes in geometry of the grooves and lands would have a significant impact on the interring gas dynamics, the thermal deformation of piston has been considered during the ring pack motion analysis in this study. In order to get the temperature distribution of piston head more quickly and accurately, an efficient method utilizing the concept of inverse heat conduction is presented. Moreover, a sensitive analysis based on the analysis of partial regression coefficients is presented to investigate the effect of groove parameters on blowby.

  14. Lubrication and tribology in seawater hydraulic piston pump

    Institute of Scientific and Technical Information of China (English)

    WANG Dong; LI Zhuang-yun; ZHU Yu-quan

    2003-01-01

    Water hydraulic systems have provoked major interest because of the human friendly and environmental safety aspects. Piston pump is one of the most frequently used hydraulic units in recent engineering technique. In water hydraulic piston pump, poor lubrication is more likely to happen than in oil hydraulic one because of difference in properties between water and oil. So there are some key problems such as corrosive wear and erosion, which are investigated briefly. Many new materials have been developed, which give longer life expectancies with water without corrosion and erosion. A new type of seawater hydraulic piston pumps with better suction characteristics had been developed at HUST. Much of this research has concentrated on new materials, structure and experiments, which are also specially introduced.

  15. Compression-cast light metal piston for internal combustion engines. Pressgegossener Leichtmetallkolben fuer Verbrennungskraftmaschinen

    Energy Technology Data Exchange (ETDEWEB)

    Mielke, S.; Henning, W.; Weiss, F.; Goelder, K.

    1991-05-16

    In a compression-cast light metal piston for internal combustion engines, fibre bodies made of short ceramic fibres, which are aligned parallel to a plane, are cast in. To improve the resistance to wear of the piston consisting of a heat-resistant magnesium alloy, the piston shank has a metallic, chemically or galvanically separate layer with a thickness of 10 to 30 m, and a hardness of 740 to 850 HV < 0.01, at least in the area of its friction surfaces.

  16. Development of wear-resistant ceramic coatings for diesel engine components

    Energy Technology Data Exchange (ETDEWEB)

    Naylor, M.G.S. (Cummins Engine Co., Inc., Columbus, IN (United States))

    1992-06-01

    The tribological properties of a variety of advanced coating materials have been evaluated under conditions which simulate the piston ring -- cylinder liner environment near top ring reversal in a heavy duty diesel engine. Coated ring'' samples were tested against a conventional pearlitic grey cast iron liner material using a high temperature reciprocating wear test rig. Tests were run with a fresh CE/SF 15W40lubricant at 200 and 350{degrees}C, with a high-soot, engine-tested oil at 200{degrees}C and with no lubrication at 200{degrees}C. For lowest wear under boundary lubricated conditions, the most promising candidates to emerge from this study were high velocity oxy-fuel (HVOF) Cr{sub 3} C{sub 2} - 20% NiCr and WC - 12% Co cermets, low temperature arc vapor deposited (LTAVD) CrN and plasma sprayed chromium oxides. Also,plasma sprayed Cr{sub 2}O{sub 3} and A1{sub 2}O{sub 3}-ZrO{sub 2} materials were found to give excellent wear resistance in unlubricated tests and at extremely high temperatures (450{degrees}C) with a syntheticoil. All of these materials would offer substantial wear reductions compared to the conventional electroplated hard chromium ring facing and thermally sprayed metallic coatings, especially at high temperatures and with high-soot oils subjected to degradation in diesel environments. The LTAVD CrN coating provided the lowest lubricated wear rates of all the materials evaluated, but may be too thin (4 {mu}m) for use as a top ring facing. Most of the coatings evaluated showed higher wear rates with high-soot, engine-tested oil than with fresh oil, with increases of more than a factor of ten in some cases. Generally, metallic materials were found to be much more sensitive to soot/oil degradation than ceramic and cermet coatings. Thus, decreased soot sensitivity'' is a significant driving force for utilizing ceramic or cermet coatings in diesel engine wear applications.

  17. Dynamically balanced, hydraulically driven compressor/pump apparatus for resonant free piston Stirling engines

    Science.gov (United States)

    Corey, John A.

    1984-05-29

    A compressor, pump, or alternator apparatus is designed for use with a resonant free piston Stirling engine so as to isolate apparatus fluid from the periodically pressurized working fluid of the Stirling engine. The apparatus housing has a first side closed by a power coupling flexible diaphragm (the engine working member) and a second side closed by a flexible diaphragm gas spring. A reciprocally movable piston is disposed in a transverse cylinder in the housing and moves substantially at right angles relative to the flexible diaphragms. An incompressible fluid fills the housing which is divided into two separate chambers by suitable ports. One chamber provides fluid coupling between the power diaphragm of the RFPSE and the piston and the second chamber provides fluid coupling between the gas spring diaphragm and the opposite side of the piston. The working members of a gas compressor, pump, or alternator are driven by the piston. Sealing and wearing parts of the apparatus are mounted at the external ends of the transverse cylinder in a double acting arrangement for accessibility. An annular counterweight is mounted externally of the reciprocally movable piston and is driven by incompressible fluid coupling in a direction opposite to the piston so as to damp out transverse vibrations.

  18. Carbon-Carbon Piston Architectures

    Science.gov (United States)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    2000-01-01

    An improved structure for carbon-carbon composite piston architectures is disclosed. The improvement consists of replacing the knitted fiber, three-dimensional piston preform architecture described in U.S. Pat.No. 4,909,133 (Taylor et al.) with a two-dimensional lay-up or molding of carbon fiber fabric or tape. Initially, the carbon fabric of tape layers are prepregged with carbonaceous organic resins and/or pitches and are laid up or molded about a mandrel, to form a carbon-fiber reinforced organic-matrix composite part shaped like a "U" channel, a "T"-bar, or a combination of the two. The molded carbon-fiber reinforced organic-matrix composite part is then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. At this point, cylindrical piston blanks are cored from the "U"-channel, "T"-bar, or combination part. These blanks are then densified by reimpregnation with resins or pitches which are subsequently carbonized. Densification is also accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston billets are machined to final piston dimensions; coated with oxidation sealants; and/or coated with a catalyst. When compared to conventional steel or aluminum alloy pistons, the use of carbon-carbon composite pistons reduces the overall weight of the engine; allows for operation at higher temperatures without a loss of strength; allows for quieter operation; reduces the heat loss; and reduces the level of hydrocarbon emissions.

  19. Method Evaluating the Durability of Aircraft Piston Engines

    Directory of Open Access Journals (Sweden)

    Luca PIANCASTELLI

    2012-12-01

    Full Text Available A significant issue in aircraft engines is quantifying residual life to overhaul. The algorithm described in this paper calculates with a good level of reliability the residual life of a petrol piston engine. The method was tested on small, latest-generation, naturally-aspirated aircraft and racing piston engines, and has been effective in several experiments. This method is implemented directly on the electronic control system of the engine with very few lines of C-code. The method can also be used in many industrial engines. This innovative method assumes that only two main factors (power level and wear affect engine durability or time between overhauls. These two factors are considered as separate and combined with worst case criteria. The wear is assumed to follow a logarithmic law and a formula similar to the Miner’s law for material fatigue is used, making it possible to calculate the power-level curve with knowledge of only two points. The wear-curve is also related to elapsed engine cycles. The algorithm is very simple and can be implemented with just a few lines of software code accessing data collected from existing sensors. The system is currently used to evaluate actual residual life of racing engines.

  20. Piezoelectric sensors to monitor lubricant film thickness at piston-cylinder contacts in a fired engine

    OpenAIRE

    2013-01-01

    The contact between the piston ring and cylinder liner is the most important sealing interface in an automotive engine. Understanding the contact interactions and lubricant film formation at this interface is crucial for the development of fuel-efficient and low emission engines. This article outlines the development of an ultrasonic approach to enable non-invasive measurement of the lubricant film thickness formed between piston and cylinder wall of a fired engine. The sensor system consiste...

  1. Piston-assisted charge pumping

    CERN Document Server

    Kaur, D; Mourokh, L

    2015-01-01

    We examine charge transport through a system of three sites connected in series in the situation when an oscillating charged piston modulates the energy of the middle site. We show that with an appropriate set of parameters, charge can be transferred against an applied voltage. In this scenario, when the oscillating piston shifts away from the middle site, the energy of the site decreases and it is populated by a charge transferred from the lower energy site. On the other hand, when the piston returns to close proximity, the energy of the middle site increases and it is depopulated by the higher energy site. Thus through this process, the charge is pumped against the potential gradient. Our results can explain the process of proton pumping in one of the mitochondrial enzymes, Complex I. Moreover, this mechanism can be used for electron pumping in semiconductor nanostructures.

  2. 49 CFR 229.55 - Piston travel.

    Science.gov (United States)

    2010-10-01

    ..., DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Brake System § 229.55 Piston travel. (a) Brake cylinder piston travel shall be sufficient to provide brake shoe clearance...

  3. On the validity range of piston theory

    CSIR Research Space (South Africa)

    Meijer, M-C

    2015-06-01

    Full Text Available International Forum on Aeroelasticity and Structural Dynamics On the validity range of Piston Theory Marius-Corne Meijer, Laurent Dala Keywords: potential flow, local piston theory, perturbation, linearization, quasi-steady. Abstract: The basis...

  4. Two piston V-type Stirling engine

    Science.gov (United States)

    Corey, John A.

    1987-01-01

    A two piston Stirling engine which includes a heat exchanger arrangement placing the cooler and regenerator directly adjacent the compression space for minimal cold duct volume; a sealing arrangement which eliminates the need for piston seals, crossheads and piston rods; and a simplified power control system.

  5. Development of new volumetric compressor with rotating cylinder and piston

    Energy Technology Data Exchange (ETDEWEB)

    Sawai, K.; Iida, N.; Futagami, Y.; Hirano, H. [Matsushita Electrical Ind. Co. Ltd., Air-Conditioning Research Lab., Shiga (Japan); Hasegawa, H. [Matsushita Electric Ind. Co. Ltd., Human Environment Systems Development Center, Osaka (Japan); Ishii, N. [Osaka Electro-Communications Lab., Faculty of Engineering, Osaka (Japan)

    1999-07-01

    We developed a new compression mechanism named 'Ellipse Compressor', which can be used in air conditioning and refrigeration. This compression mechanism is basically rotary type machine, which consists of rotating cylinder and rotating piston without vane. It has high potentiality to exhibit high reliability in R410A refrigerant, because of low wear without extreme high pressure on the sliding parts. This paper presents a compression mechanism, theoretical analysis, a prototype model design, performance and loss analysis. Test results indicated that the performance of the prototype model exhibited almost the same as that of scroll compressor for room air conditioner. Durability test on the room air conditioner at heavy heating condition resulted in the low level of wear of the sliding parts, without special materials. (Author)

  6. Investigation of Valve Plate in Water Hydraulic Axial Piston Motor

    Institute of Scientific and Technical Information of China (English)

    聂松林; 李壮云; 等

    2002-01-01

    This paper has introduced the developments of water hydraulic axial piston equipments.According to the effects of physicochemical properties of water on water hydraulic components,a novel valve plate for water hydraulic axial motor has been put forward,whose moment exerted by the fluid field between valve plate and bearing plate is balanced entirely.The material screening experiment of valve plate is done on the test rig.Through numerical simulation the effects of some geometry parameters on the performance of water hydraulic motor have been studied.The silencing grooves on the valve plate in water hydraulic motor can reduce the pressure shock and the occurrence of cavitation effectively.It is evident that the appropriate structure should change the wear status between matching paris and reduces the wear and specific pressure of the matching pairs.The specimen with the new type valve plate is used in a tool system.

  7. Study on the engine oil's wear based on the flash point

    Science.gov (United States)

    Niculescu, R.; Iorga-Simăn, V.; Trică, A.; Clenci, A.

    2016-08-01

    Increasing energy performance of internal combustion engines is largely influenced by frictional forces that arise between moving parts. Thus, in this respect, the nature and quality of the engine oil used is an important factor. Equally important is the effect of various engine injection strategies upon the oil quality. In other words, it's of utmost importance to maintain the quality of engine oil during engine's operation. Oil dilution is one of the most common causes that lead to its wear, creating lubrication problems. Moreover, at low temperatures operating conditions, the oil dilution with diesel fuel produces wax. When starting the engine, this may lead to lubrication deficiencies and even oil starvation with negative consequences on the engine mechanism parts wear (piston, rings and cylinders) but also crankcase bearings wear.Engine oil dilution with diesel fuel have several causes: wear of rings and/or injectors, late post-injection strategy for the sake of particulate filter regeneration, etc.This paper presents a study on the degree of deterioration of engine oils as a result of dilution with diesel fuel. The analysed oils used for this study were taken from various models of engines equipped with diesel particulate filter. The assessment is based on the determination of oil flash point and dilution degree using the apparatus Eraflash produced by Eralytics, Austria. Eraflash measurement is directly under the latest and safest standards ASTM D6450 & D7094), which are in excellent correlation with ASTM D93 Pensky - Martens ASTM D56 TAG methods; it uses the Continuous Closed Cup method for finding the Flash Point (CCCFP).

  8. Comparison of Nitinol Stapes Pistons with Conventional Stapes Pistons: A Cadaver Study

    Science.gov (United States)

    2011-01-01

    Comparison of Nitinol Stapes Pistons with Conventional Stapes Pistons: A Cadaver Study Samuel A. Spear1 and James V. Crawford2 1 48th Medical Group, ENT...cited. Objective. To visually compare the Nitinol “smart” stapes prosthesis to conventional manual crimping stapes pistons in temporal bone cadaver...answer questions about each stapes piston. The answers to the survey were then recorded for analysis. Results. 8 of 9 Nitinol pistons were described as

  9. Eye Wear

    Science.gov (United States)

    Eye wear protects or corrects your vision. Examples are Sunglasses Safety goggles Glasses (also called eyeglasses) Contact ... jobs and some sports carry a risk of eye injury. Thousands of children and adults get eye ...

  10. Remaining useful life prediction based on the Wiener process for an aviation axial piston pump

    Institute of Scientific and Technical Information of China (English)

    Wang Xingjian; Lin Siru; Wang Shaoping; He Zhaomin; Zhang Chao

    2016-01-01

    An aviation hydraulic axial piston pump’s degradation from comprehensive wear is a typical gradual failure model. Accurate wear prediction is difficult as random and uncertain char-acteristics must be factored into the estimation. The internal wear status of the axial piston pump is characterized by the return oil flow based on fault mechanism analysis of the main frictional pairs in the pump. The performance degradation model is described by the Wiener process to predict the remaining useful life (RUL) of the pump. Maximum likelihood estimation (MLE) is performed by utilizing the expectation maximization (EM) algorithm to estimate the initial parameters of the Wiener process while recursive estimation is conducted utilizing the Kalman filter method to estimate the drift coefficient of the Wiener process. The RUL of the pump is then calculated accord-ing to the performance degradation model based on the Wiener process. Experimental results indi-cate that the return oil flow is a suitable characteristic for reflecting the internal wear status of the axial piston pump, and thus the Wiener process-based method may effectively predicate the RUL of the pump.

  11. Development of wear-resistant ceramic coatings for diesel engine components. Volume 1, Coating development and tribological testing: Final report: DOE/ORNL Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    Naylor, M.G.S. [Cummins Engine Co., Inc., Columbus, IN (United States)

    1992-06-01

    The tribological properties of a variety of advanced coating materials have been evaluated under conditions which simulate the piston ring -- cylinder liner environment near top ring reversal in a heavy duty diesel engine. Coated ``ring`` samples were tested against a conventional pearlitic grey cast iron liner material using a high temperature reciprocating wear test rig. Tests were run with a fresh CE/SF 15W40lubricant at 200 and 350{degrees}C, with a high-soot, engine-tested oil at 200{degrees}C and with no lubrication at 200{degrees}C. For lowest wear under boundary lubricated conditions, the most promising candidates to emerge from this study were high velocity oxy-fuel (HVOF) Cr{sub 3} C{sub 2} - 20% NiCr and WC - 12% Co cermets, low temperature arc vapor deposited (LTAVD) CrN and plasma sprayed chromium oxides. Also,plasma sprayed Cr{sub 2}O{sub 3} and A1{sub 2}O{sub 3}-ZrO{sub 2} materials were found to give excellent wear resistance in unlubricated tests and at extremely high temperatures (450{degrees}C) with a syntheticoil. All of these materials would offer substantial wear reductions compared to the conventional electroplated hard chromium ring facing and thermally sprayed metallic coatings, especially at high temperatures and with high-soot oils subjected to degradation in diesel environments. The LTAVD CrN coating provided the lowest lubricated wear rates of all the materials evaluated, but may be too thin (4 {mu}m) for use as a top ring facing. Most of the coatings evaluated showed higher wear rates with high-soot, engine-tested oil than with fresh oil, with increases of more than a factor of ten in some cases. Generally, metallic materials were found to be much more sensitive to soot/oil degradation than ceramic and cermet coatings. Thus, decreased ``soot sensitivity`` is a significant driving force for utilizing ceramic or cermet coatings in diesel engine wear applications.

  12. Integration of Gas Nitrocarburising and Oxidising in a Mass Production Line for Brake Pistons

    Institute of Scientific and Technical Information of China (English)

    Gero Walkowiak; Dieter M(u)ller; Uwe Zeibig

    2004-01-01

    The combination of wear- and corrosion resistance is a demand to a multitude of automotive parts. Several metallic coatings as hard/soft chromium or electroless nickel have been the conventional surface protection e.g. on parts as brake pistons and shock absorber or gas spring piston rods. The Corr-I-Dur(R) process - a special gasnitrocarburising and oxidising technology - has a huge potential not only in substituting those coatings but also in delivering surfaces with higher quality.The benefits of the replacement of soft chromium with Corr-I-Dur(R) and the implementation of the process in the customers production line with an annual capacity of 17 million brake pistons is described in this presentation. Starting with the demands on wear- and corrosion resistance the way of process development and the design of applicative equipment is shown. The result is a tailor-made surface solution with superior quality for deep drawn brake pistons. Two main disadvantagesoutgassing of the chromium layer and reduced corrosion resistance on the inner diameter - are eliminated by the replacement with Corr-I-Dur(R). The process-sure achievement of enhanced corrosion resistance, uniform layer thickness, negligible distortion as well as environmental and economical advantages make Corr-I-Dur(R) an excellence choice for this application.

  13. Tooth wear

    Directory of Open Access Journals (Sweden)

    Tušek Ivan

    2014-01-01

    Full Text Available Tooth wear is the loss of dental hard tissue that was not caused by decay and represents a common clinical problem of modern man. In the etiology of dental hard tissue lesions there are three dominant mechanisms that may act synergistically or separately:friction (friction, which is caused by abrasion of exogenous, or attrition of endogenous origin, chemical dissolution of dental hard tissues caused by erosion, occlusal stress created by compression and flexion and tension that leads to tooth abfraction and microfracture. Wear of tooth surfaces due to the presence of microscopic imperfections of tooth surfaces is clinically manifested as sanding veneers. Tribology, as an interdisciplinary study of the mechanisms of friction, wear and lubrication at the ultrastructural level, has defined a universal model according to which the etiopathogenesis of tooth wear is caused by the following factors: health and diseases of the digestive tract, oral hygiene, eating habits, poor oral habits, bruxism, temporomandibular disorders and iatrogenic factors. Attrition and dental erosion are much more common in children with special needs (Down syndrome. Erosion of teeth usually results from diseases of the digestive tract that lead to gastroesophageal reflux (GER of gastric juice (HCl. There are two basic approaches to the assessment of the degree of wear and dental erosion. Depending on the type of wear (erosion, attrition, abfraction, the amount of calcium that was realised during the erosive attack could be determined qualitatively and quantitatively, or changes in optical properties and hardness of enamel could be recorded, too. Abrasion of teeth (abrasio dentium is the loss of dental hard tissue caused by friction between the teeth and exogenous foreign substance. It is most commonly provoked by prosthetic dentures and bad habits, while its effect depends on the size of abrasive particles and their amount, abrasive particle hardness and hardness of tooth

  14. 具有仿生条纹结构的内燃机活塞疲劳特性回归分析%Regression analysis of fatigue property of internal combustion engine piston with bionic stripe structure

    Institute of Scientific and Technical Information of China (English)

    吴波; 丛茜; 杨利; 刘洋; 金绍江; 王洪臣; 刘鸿涛; 田为军

    2016-01-01

    were got. Then we could observe the stress, strain and deformation of piston from coupled thermo-mechanical analysis results. Second, most animals have evolved and formed non-smooth surface, which can reduce drag and resist wear. The soil animal earthworm is one of the perfect animals, which has non-smooth surface. It shuttles back and forth in the soil, which was just like piston doing reciprocating motion in air cylinder. We copied stripes and holes from earthworm and enlarged them. The enlarging scale was decided according to piston size. Then the stripes and holes on the piston skirt were processed. The bionic piston could resist attrition and heat dissipation, and increase fatigue life. The coupled thermo-mechanical analysis results of standard piston showed that the stress of perfective aspect of piston was non-uniform. The stress was concentrated on the piston top and the third ring groove, and the maximum deformation was at the bottom of piston skirt. So this design made depth, width and space of stripe variable size. For the stripe, the closer to the top of piston, the larger the depth, width and space between columns. There were 8 stripes on the skirt from top to bottom, and every adjacent 2 stripes had the same size (1 and 2, 3 and 4, 5 and 6, 7 and 8). Third, the three-level and three-factor orthogonal array was used, and 9 testing programs of bionic pistons were made. The first factor was stripe distribution pattern, and it included 3 levels which were stripe distribution, drilling in stripe and a line of stripe with a line of bore. The second factor was stripe depth, and it included 3 levels which were A (0.8, 0.7, 0.6 and 0.5 mm), B (0.9, 0.8, 0.7 and 0.6 mm) and C (1, 0.9, 0.8 and 0.7 mm). The third factor was stripe width, and it included 3 levels which were I (0.8, 0.7, 0.6 and 0.5 mm), II (0.9, 0.8, 0.7 and 0.6 mm) and III (1, 0.9, 0.8 and 0.7 mm). The coupled thermo-mechanical analysis was carried out on 9 bionic pistons. Three typical indices that

  15. Fluid structure interaction in piston diaphragm pumps

    NARCIS (Netherlands)

    Van Rijswick, R.; Van Rhee, C.

    2013-01-01

    Piston diaphragm pumps are used world-wide for the transport of aggressive and/or abrasive fluids in the chemical, mining and mineral processing industries. Figure 1 shows a cross section of a piston diaphragm pump as is used in the mining and mineral processing industries for the transport of

  16. Fluid structure interaction in piston diaphragm pumps

    NARCIS (Netherlands)

    Van Rijswick, R.; Van Rhee, C.

    2013-01-01

    Piston diaphragm pumps are used world-wide for the transport of aggressive and/or abrasive fluids in the chemical, mining and mineral processing industries. Figure 1 shows a cross section of a piston diaphragm pump as is used in the mining and mineral processing industries for the transport of miner

  17. Casting of Motorcycle Piston from Aluminium Piston Scrap using Metallic Mould

    Directory of Open Access Journals (Sweden)

    Francis Uchenna OZIOKO

    2012-11-01

    Full Text Available The casting of motorcycle piston was carried out using metallic mould. The prepared piston sand core was positioned in the mould to provide casting with contours and cavities. The molten metal of required composition was poured into the metallic mould, allowed to solidify and take the desired shape of the cavity. Aluminium silicon piston scraps were used as the casting material. Melting of the aluminium piston scraps was achieved using local crucible furnace and finally pouring the molten metal into the metallic mould having the prepared piston sand core in place to obtain the piston. After fettling and cleaning, the casting was found to be good. The composition test revealed that the scrap piston was made from LM29 aluminium alloy. The cast piston was machined and subjected to performance rating test in a Jincheng AX100 motorcycle engine. The rating used was based on a scale from 1 to 10. The higher the rating, the better the evaluation of the piston in the specific area rated. Deposits are evaluated by appearance, ranging from 10 (clean - absence of deposits to 0.0 (maximum deposits. In spite of various production constraints the result of the performance test was good. The rating showed that the locally cast piston compared favourably with imported piston.

  18. Low-Wear Ball-Bearing Separator

    Science.gov (United States)

    Hawkinson, Elden L.

    1991-01-01

    Proposed ball-bearing separator for use in cryogenic pump stronger and more resistant to wear. Consists of molded plastic-and-metal composite ring imbued with solid lubricant and containing embedded metal ring. Obtains combination of strength and lubricity. Before molding and machining, ring includes tooling portion for handling and indexing. Molded composite blend of PTFE and fluorinated ethylene/propylene (FEP) filled with brass and bronze powder and molybdenum disulfide powder.

  19. Effects of piston speed, compression ratio and cylinder geometry on system performance of a liquid piston

    Directory of Open Access Journals (Sweden)

    Mutlu Mustafa

    2016-01-01

    Full Text Available Energy storage systems are being more important to compensate irregularities of renewable energy sources and yields more profitable to invest. Compressed air energy storage (CAES systems provide sufficient of system usability, then large scale plants are found around the world. The compression process is the most critical part of these systems and different designs must be developed to improve efficiency such as liquid piston. In this study, a liquid piston is analyzed with CFD tools to look into the effect of piston speed, compression ratio and cylinder geometry on compression efficiency and required work. It is found that, increasing piston speeds do not affect the piston work but efficiency decreases. Piston work remains constant at higher than 0.05 m/s piston speeds but the efficiency decreases from 90.9 % to 74.6 %. Using variable piston speeds has not a significant improvement on the system performance. It is seen that, the effect of compression ratio is increasing with high piston speeds. The required power, when the compression ratio is 80, is 2.39 times greater than the power when the compression ratio is 5 at 0.01 m/s piston speed and 2.87 times greater at 0.15 m/s. Cylinder geometry is also very important because, efficiency, power and work alter by L/D, D and cylinder volume respectively.

  20. Prediction of Cone Crusher Performance Considering Liner Wear

    Directory of Open Access Journals (Sweden)

    Yanjun Ma

    2016-12-01

    Full Text Available Cone crushers are used in the aggregates and mining industries to crush rock material. The pressure on cone crusher liners is the key factor that influences the hydraulic pressure, power draw and liner wear. In order to dynamically analyze and calculate cone crusher performance along with liner wear, a series of experiments are performed to obtain the crushed rock material samples from a crushing plant at different time intervals. In this study, piston die tests are carried out and a model relating compression coefficient, compression ratio and particle size distribution to a corresponding pressure is presented. On this basis, a new wear prediction model is proposed combining the empirical model for predicting liner wear with time parameter. A simple and practical model, based on the wear model and interparticle breakage, is presented for calculating compression ratio of each crushing zone along with liner wear. Furthermore, the size distribution of the product is calculated based on existing size reduction process model. A method of analysis of product size distribution and shape in the crushing process considering liner wear is proposed. Finally, the validity of the wear model is verified via testing. The result shows that there is a significant improvement of the prediction of cone crusher performance considering liner wear as compared to the previous model.

  1. Wear simulation effects on overdenture stud attachments.

    Science.gov (United States)

    Rutkunas, Vygandas; Mizutani, Hiroshi; Takahashi, Hidekazu; Iwasaki, Naohiko

    2011-01-01

    The aim of this study was to evaluate wear effects on overdenture resilient attachments. Six commercially available attachments were investigated: ERA orange and white (EO and EW), Locator pink, white and blue (LRP, LRW and LRB) and OP anchor (OP). Five specimens were used for wear simulation while other two specimens served as controls. Fifteen thousands insertion-removal cycles were simulated. Dimensional changes and surface characteristics were evaluated using light microscopy and SEM, respectively. Sudden decrease of retentive force was characteristic for EO and EW attachments. Retentive force of Locator attachments fluctuated throughout the wear simulation period. Dimensional changes and surface wear was more expressed on plastic cores than on plastic rings of attachment males. Based on SEM analysis, some of the specimens obtained smoother surface after wear simulation. Mechanism of retention loss of resilient overdenture attachments can be only partially explained by dimensional changes and surface alterations.

  2. Electromagnetic Casimir piston in higher dimensional spacetimes

    CERN Document Server

    Teo, L P

    2011-01-01

    We consider the Casimir effect of the electromagnetic field in a higher dimensional spacetime of the form $M\\times \\mathcal{N}$, where $M$ is the 4-dimensional Minkowski spacetime and $\\mathcal{N}$ is an $n$-dimensional compact manifold. The Casimir force acting on a planar piston that can move freely inside a closed cylinder with the same cross section is investigated. Different combinations of perfectly conducting boundary conditions and infinitely permeable boundary conditions are imposed on the cylinder and the piston. It is verified that if the piston and the cylinder have the same boundary conditions, the piston is always going to be pulled towards the closer end of the cylinder. However, if the piston and the cylinder have different boundary conditions, the piston is always going to be pushed to the middle of the cylinder. By taking the limit where one end of the cylinder tends to infinity, one obtains the Casimir force acting between two parallel plates inside an infinitely long cylinder. The asymptot...

  3. Engineering wear-resistant surfaces in automotive aluminum

    Science.gov (United States)

    Kavorkijan, V.

    2003-02-01

    Inadequate wear resistance and low seizure loads prevent the direct use of aluminum alloys in automotive parts subject to intensive friction combined with high thermal and mechanical loading, such as brake discs, pistons, and cylinder liners. To enable the use of aluminum alloys in the production of automotive brake discs and other wear-resistant products, the insertion of a monolithic friction cladding rather than surface coating has been considered in this work. Three experimental approaches, two based on the pressure-less infiltration of porous ceramic preforms and one based on the subsequent hot rolling of aluminum and metal-matrix composite strips, are currently under investigation.

  4. Conspray dynamic sleeve piston coal feeder. Phase II. Verification tests. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    1984-01-26

    This report details the performance of Phase II: Verification Tests of the Conspray dynamic sleeve piston coal feeder. The machine performed for 200 hours at 700 psi backpressure, utilizing a 70% to 200 mesh Utah bituminous coal as feedstock. All test work was satisfactorily completed. A post-test inspection was performed. A report of component wear and failures incurred in testing is included as well as suggestions for machine upgrades. The overall conclusion is that the dynamic sleeve piston feeder has proven its ability to operate safely and reliably. When problems have occurred, the machine has demonstrated inherent safety by shutting down without endangering process or personnel. With the recommended improvements incorporated into the feeder, the unit will be ready for installation on a pilot scale coal gasifier. 9 figures, 11 tables.

  5. Drive piston assembly for a valve actuator assembly

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Zongxuan (Troy, MI)

    2010-02-23

    A drive piston assembly is provided that is operable to selectively open a poppet valve. The drive piston assembly includes a cartridge defining a generally stepped bore. A drive piston is movable within the generally stepped bore and a boost sleeve is coaxially disposed with respect to the drive piston. A main fluid chamber is at least partially defined by the generally stepped bore, drive piston, and boost sleeve. First and second feedback chambers are at least partially defined by the drive piston and each are disposed at opposite ends of the drive piston. At least one of the drive piston and the boost sleeve is sufficiently configured to move within the generally stepped bore in response to fluid pressure within the main fluid chamber to selectively open the poppet valve. A valve actuator assembly and engine are also provided incorporating the disclosed drive piston assembly.

  6. Systematic parametric design/calculation of the piston rod unit

    Science.gov (United States)

    Kacani, V.

    2015-08-01

    In this article a modern and economic method for the strength calculation of the piston rod unit and its components under different operating conditions will be presented. Herefore the commercial FEA - Software will be linked with the company-owned calculation tools. The parametric user input will be followed by an automatic Pre- and Postprocessing. Afterwards the strength calculation is processed on all critical points of the piston rod connection, assisted by an extra module, based on general standards and special codes for reciprocating compressors. In this process most arrangements of the piston rod unit as well as the special geometries of the single-components (piston, piston rod and piston nut) can be considered easily. In this article the modeling of the notches, especially on the piston rod, piston as well as the piston nut will be covered in detail.

  7. Experimental and Dynamic Study of the Piston Rod Lateral Friction for the Twin-Tube Hydraulic Shock Absorber

    Directory of Open Access Journals (Sweden)

    Yanqing Liu

    2003-01-01

    Full Text Available In this paper, dynamic loads acting on a twin-tube hydraulic shock absorber are derived out both in wheel and axle planes by modeling mechanically car rear suspensions, and internal and external forces that yield lateral surface damage and wear-out of the piston rod for the absorber are analyzed according to bench and real road test measures. From viewpoint of vehicle system dynamics and experiment, such key factors as road unevenness, very high car speed and severe shock induced vibrations are investigated, by which stochastic bending moments and dramatically increasing shock loading are introduced directly to the piston rod. From viewpoint of the whole car assembly, on the other hand, due to hardly perfectly placements of the piston rods in their positions between the car suspension and body, unacceptable manufacturing quality of the body may cause additional dynamic forces on the piston rod. Significant results obtained by theoretical and experimental analysis of lateral frictions of the piston rod are presented systematically for improving design of the shock absorber.

  8. Insulated Piston Heads for Diesel Engines

    Science.gov (United States)

    Tricoire, A.; Kjellman, B.; Wigren, J.; Vanvolsem, M.; Aixala, L.

    2009-06-01

    Widely studied in the 1980s, the insulation of pistons in engines aimed at reducing the heat losses and thus increasing the indicated efficiency. However, those studies stopped in the beginning of the 1990s because of NO x emission legislation and also because of lower oil prices. Currently, with the improvement of exhaust after treatment systems (diesel particulate filter, selective catalytic reduction, and diesel oxidation catalyst) and engine technologies (exhaust gas recirculation), there are more trade-offs for NO x reduction. In addition, the fast rise of the oil prices tends to lead back to insulation technologies in order to save fuel. A 1 mm thick plasma sprayed thermal barrier coating with a graded transition between the topcoat and the bondcoat was deposited on top of a serial piston for heavy-duty truck engines. The effects of the insulated pistons on the engine performance are also discussed, and the coating microstructure is analyzed after engine test.

  9. NEW METHOD TO MEASURE PISTON SKIRT DIMENSIONS

    Institute of Scientific and Technical Information of China (English)

    Qin Yuexia; Hu Dejin

    2004-01-01

    The measurement of the middle-convex and varying ellipse profile of a piston skirt is a key technology because of its complex profile and high precision. Generally, a piston is measured on special device after it is machined. High accuracy can be achieved through this off-line measurement, but the result diverges from the actual dimension. Therefore, a no-contact in-site measurement system is proposed. A laser displacement meter is used to measure the profile of the piston skirt. A computer connected to the meter is used to process the measured data. A regression analysis method is used to process the ellipse section data. The method of moving average is used to process the middle-convex curve data. By using the given system, high measurement accuracy can be gained, and the production requirement is met.

  10. Development of deep drawn aluminum piston tanks

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J.C.; Bronder, R.L.; Kilgard, L.W.; Evans, M.C.; Ormsby, A.E.; Spears, H.R.; Wilson, J.D.

    1990-06-08

    An aluminum piston tank has been developed for applications requiring lightweight, low cost, low pressure, positive-expulsion liquid storage. The 3 liter (183 in{sup 3}) vessel is made primarily from aluminum sheet, using production forming and joining operations. The development process relied mainly on pressurizing prototype parts and assemblies to failure, as the primary source of decision making information for driving the tank design toward its optimum minimum-mass configuration. Critical issues addressed by development testing included piston operation, strength of thin-walled formed shells, alloy choice, and joining the end cap to the seamless deep drawn can. 9 refs., 8 figs.

  11. Staged combustion with piston engine and turbine engine supercharger

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Larry E [Los Gatos, CA; Anderson, Brian L [Lodi, CA; O' Brien, Kevin C [San Ramon, CA

    2011-11-01

    A combustion engine method and system provides increased fuel efficiency and reduces polluting exhaust emissions by burning fuel in a two-stage combustion system. Fuel is combusted in a piston engine in a first stage producing piston engine exhaust gases. Fuel contained in the piston engine exhaust gases is combusted in a second stage turbine engine. Turbine engine exhaust gases are used to supercharge the piston engine.

  12. Fault Wear and Friction Evolution: Experimental Analysis

    Science.gov (United States)

    Boneh, Y.; Chang, J. C.; Lockner, D. A.; Reches, Z.

    2011-12-01

    Wear is an inevitable product of frictional sliding of brittle rocks as evidenced by the ubiquitous occurrence of fault gouge and slickenside striations. We present here experimental observations designed to demonstrate the relationship between wear and friction and their governing mechanisms. The experiments were conducted with a rotary shear apparatus on solid, ring-shaped rock samples that slipped for displacements up to tens of meters. Stresses, wear and temperature were continuously monitored. We analyzed 86 experiments of Kasota dolomite, Sierra White granite, Pennsylvania quartzite, Karoo gabbro, and Tennessee sandstone at slip velocities ranging from 0.002 to 0.97 m/s, and normal stress from 0.25 to 6.9 MPa. We conducted two types of runs: short slip experiments (slip distance mechanisms; and long slip experiments (slip distance > 3 m) designed to achieve mature wear conditions and to observe the evolution of wear and friction as the fault surfaces evolved. The experiments reveal three wear stages: initial, running-in, and steady-state. The initial stage is characterized by (1) discrete damage striations, the length of which is comparable to total slip , and local pits or plow features; (2) timing and magnitude of fault-normal dilation corresponds to transient changes of normal and shear stresses; and (3) surface roughness increasing with the applied normal stress. We interpret these observations as wear mechanisms of (a) plowing into the fresh rock surfaces; (b) asperity breakage; and (c) asperity climb. The running-in stage is characterized by (1) intense wear-rate over a critical wear distance of Rd = 0.3-2 m; (2) drop of friction coefficient over a weakening distance of Dc = 0.2-4 m; (3) Rd and Dc display positive, quasi-linear relation with each other. We interpret these observations as indicating the organizing of newly-created wear particles into a 'three-body' structure that acts to lubricate the fault (Reches & Lockner, 2010). The steady

  13. Alcohol fuels in spark ignition engines. Use characteristics and engine wear. Alkoholipolttoaineet ottomoottorissa. Kaeyttoeominaisuudet ja moottorin kuluminen

    Energy Technology Data Exchange (ETDEWEB)

    Nylund, N.-O.; Kytoe, M.; Eklund, T.; Sipilae, K.

    1986-09-01

    A field test with different alcohol fuels was carried out at the Technical Research Centre of Finland in 1981-1984. The test involved 19 passenger cars. The engines of the test vehicles were dismantled both before and after the test. In addition to engine wear, driveability was also studied during the test. Finland's cold climate emphasizes difficulties arising with alcohol fuels. E15/M15 fuels demand only minor adjustment in the fuel systems to restore driveability. E15 fuel was used both in new and old cars and this fuel did not cause any corrosion problems. M15 is a more difficult fuel both in regard to corrosion and fuel stability. None of the test engines showed signs of accelerated wear of the kind that could have shortened the lifetime of the engine considerably. Cylinders, piston rings, earings and valve train were monitored. Temperature has a strong effect on engine wear and the driveability of engines running on neat alcohol have been presented. For these reasons the Research Centre developed, in cooperation with Oy Saab-Valmet Ab, a dual fuel system for gasoline and alcohol. The system is automatic and change-over from gasoline to alcohol takes place at a coolant temperature of 70 deg C. In two series of tests dual fuel cars and cars with a simple fuel system (gasoline as starting aid) were compared regarding engine wear and driveability. The second series of tests involved 2+2 cars. Each car was driven 50,000 km. The driveability of the dual fuel car does not differ from that of a normal gasoline vehicle. Including the portion of gasoline in the main M90 fuel, the part of energy coming gasoline was 30-40%. The cam/tappet mechanism was found critical with regard to wear. In the most severe operating conditions only the dual fuel system can prevent the engine from excessive wear. A very efficient system for preheating the inlet air was used in all neat alcohol test vehicles.

  14. How Hot Can a Fire Piston Get?

    Science.gov (United States)

    Scott-Brown, J. A.; Cunningham, O. A.; Goad, B. C.

    2010-01-01

    The fire piston is just a sealed syringe containing a small amount of tinder. When the plunger is forced downwards, the air inside is compressed and heats up, setting fire to the tinder. It has been used as a convenient and portable way of starting fires "over a wide area from northern Burma and Siam through the Malay Peninsula and the Malayan…

  15. Experiments with vortex rings in air

    Science.gov (United States)

    Hernández, R. H.; Cibert, B.; Béchet, C.

    2006-09-01

    We report quantitative experimental measurements of the instability of vortex rings generated in air. Vortex rings are created by pushing air through the circular orifice of a cylindrical cavity with a flat piston driven by a loudspeaker. Hot-wire anemometry provides accurate measurements of the velocity profile at all stages of the ring formation including stable and unstable rings. Flow visualization using a laser light sheet shows that the initially undisturbed vortex ring is progressively deformed in the azimuthal direction giving rise to a wavy azimuthal and periodic pattern in the circumference of the ring. The wavy pattern is steady, i.e., it does not rotate or translate during the ring's motion. However as the vortex motion progresses in the axial direction, the displaced portions of the ring are convected away from the initial undisturbed position and the wavy pattern grows with local Reynolds number.

  16. Wearing gloves in the hospital

    Science.gov (United States)

    ... gloves; PPE - wearing gloves; Nosocomial infection - wearing gloves; Hospital acquired infection - wearing gloves ... Wearing gloves in the hospital helps prevent the spread of germs. This helps protect both patients and health care workers from infection.

  17. Comparative wear mapping techniques

    DEFF Research Database (Denmark)

    Alcock, J.; Sørensen, Ole Toft; Jensen, S.

    1996-01-01

    Pin-on-disc tests of tungsten carbide pins against silicon carbide discs were performed and wear rate, mechanism and friction maps constructed. Correlations were observed between the wear mode and the friction of the pin-disc interface, and between the qualitative incidence of disruptive wear...

  18. An Investigation into the Behavior of Disc Blake Wear

    Directory of Open Access Journals (Sweden)

    Muneer A. H.Jassim

    2007-01-01

    Full Text Available A real method of predication brake pad wear ,could lead to substantiol economies of time and money. This paper describes how such a procedure has been used and gives the results to establish is reliability by comparing the predicted wear with that which actually occurs in an existing service. The experimental work was carried out on three different commercial samples ,tested under different operation conditions (speed,load,time...etcusing a test ring especially modified for this purpose. Abrasive wear is mainly studied , since it is the type of wear that takes place in such arrangements. Samples wear tested in presences of sand or mud between the mating surfaces under different operational conditions of speed, load and braking time .Mechanical properties of the pad material samples (hardness, young,s modulus and collapse load under pure bending condition wear established . The thermal conductivity and surface roughness of the pad material wear also found in order to enable comparison between the surface condition before and after testing. Sliding velocity had a small effect on the wear rate but it had great effect on friction coefficient. Wear rate was affected mainly by the surface temperature which causing a reduction friction coefficient and increasing the wear rate. Surface roughness had almost no effect on the wear rate since it was proved experimentally ,that the surface becomes softer during operation .mechanical properties of the pad material had fluctuating effect on wear rate. The existence of solid particles between pad and disc increasing wear rate and friction coefficient while the mud caused a reduction in wear rate of the pad surface since it acts as a lubricant absorbing the surface heat generated during sliding the area of contact between pad and disc. wear rate obtained experimentally agreed fairly well that found from empirically obtained equations.

  19. Wear Debris Analysis:Fundamental Principle of Wear-Graphy

    Institute of Scientific and Technical Information of China (English)

    陈铭; 王伟华; 殷勇辉; 王成焘

    2004-01-01

    A new wear-graphy technology was developed, which can simultaneously identify the shape and composition of wear debris, for both metals and non-metals.The fundamental principles of the wear-graphy system and its wear-gram system are discussed here.A method was developed to distribute wear debris on a slide uniformly to reduce overlapping of wear debris while smearing.The composition identification analyzes the wear debris using the scanning electron microscope (SEM) energy spectrum, infrared-thermal imaging and X-ray imaging technology.A wear debris analysis system based on database techniques is demonstrated, and a visible digitized wear-gram is acquired based on the information of wear debris with image collection and processing of the wear debris.The method gives the morphological characteristics of the wear debris, material composition identification of the wear debris, intelligent recognition of the wear debris, and storage and management of wear debris information.

  20. Adaptive FEM Analysis of the Temperature Field of Pistons in Diesel Engines and Their Thermal Stress and Deformation Calculation

    Institute of Scientific and Technical Information of China (English)

    覃文洁; 张儒华; 左正兴

    2004-01-01

    The adaptive FEM analysis of the temperature field of the piston in one diesel engine is given by using the ANSYS software. By making full use of the post results provided by the software, the posteriori error estimation and adaptive accuracy meshing algorithm is developed. So the blindness of the mesh design through experiences can be avoided, and the accuracy requirement is adapted to the relative temperature gradient distribution across the entire domain. Therefore the meshes and solutions can be obtained at the same time. Based on the temperature field analysis, the thermal stress and deformation fields are calculated as well. The results show that the stress concentrates on the edge of the piston pin boss and the inside surface of the first ring groove, and the deformation of the head of the piston is greatest. But the difference between the long and short axes of the bottom cross section is greatest.

  1. On the Influence of Piston and Cylinder Density in Tribodynamics of a Radial Piston Digital Fluid Power Displacement Motor

    DEFF Research Database (Denmark)

    Johansen, Per; Roemer, Daniel Beck; Andersen, Torben O.;

    2015-01-01

    In the past three decades an increasing amount of research has been performed in the field of tribodynamics of fluid power pumps and motors. The main incentives for this research are optimization of reliability and eciency through the study of loss and wear mechanisms. These mechanisms are very d...... assessment of the applicability, of the force balance condition, if it is used in multibody tribodynamic simulations of radial piston digital fluid power displacement motors....... analysis or optimization. The coupling between multibody dynamics and fluid mechanics depend on the formulation of the solid body motion equations, where two approaches have historically been used. One approach is where the external forces on any lubricated joint are balanced by the fluid forces......, such that solid body inertia is neglected. The other approach includes the inertia terms in the calculation of microdynamics. The inclusion of inertia terms entails a need for smaller time steps in comparison to the force balance approach, wherefore it is of interest to analyze the influence of the inertia term...

  2. Casimir pistons with general boundary conditions

    Directory of Open Access Journals (Sweden)

    Guglielmo Fucci

    2015-02-01

    Full Text Available In this work we analyze the Casimir energy and force for a scalar field endowed with general self-adjoint boundary conditions propagating in a higher dimensional piston configuration. The piston is constructed as a direct product I×N, with I=[0,L]⊂R and N a smooth, compact Riemannian manifold with or without boundary. The study of the Casimir energy and force for this configuration is performed by employing the spectral zeta function regularization technique. The obtained analytic results depend explicitly on the spectral zeta function associated with the manifold N and the parameters describing the general boundary conditions imposed. These results are then specialized to the case in which the manifold N is a d-dimensional sphere.

  3. Lagrangian analysis of fluid transport in empirical vortex ring flows

    OpenAIRE

    Shadden, Shawn C.; Dabiri, John O.; Marsden, Jerrold E.

    2006-01-01

    In this paper we apply dynamical systems analyses and computational tools to fluid transport in empirically measured vortex ring flows. Measurements of quasisteadily propagating vortex rings generated by a mechanical piston-cylinder apparatus reveal lobe dynamics during entrainment and detrainment that are consistent with previous theoretical and numerical studies. In addition, the vortex ring wake of a free-swimming Aurelia aurita jellyfish is measured and analyzed in the framework of dynami...

  4. Polymer wear evaluation

    DEFF Research Database (Denmark)

    Lagerbon, Mikkel; Sivebæk, Ion Marius

    2012-01-01

    the safety of the patients. Prediction of the wear of polymers is complicated by the low thermal conductivity of this kind of material. It implies that any acceleration of testing conditions by increased contact pressure and/or sliding velocity will make the polymer fail due to exaggerated heat buildup......Polymer wear plays an increasing role in manufacturing of machine parts for e.g. medical devices. Some of these have an expected lifetime of five to eight years during which very little wear of the components is acceptable. Too much wear compromises the dosage accuracy of the device and thereby....... This is not the kind of wear observed in medical devices. In the present work a method was developed capable of evaluating the wear progression in polymer-polymer contacts. The configuration of the setup is injection moulded specimens consisting of an upper part having a toroid shape and a lower flat part. The sliding...

  5. Polymer wear evaluation

    DEFF Research Database (Denmark)

    Lagerbon, Mikkel; Sivebæk, Ion Marius

    2012-01-01

    Polymer wear plays an increasing role in manufacturing of machine parts for e.g. medical devices. Some of these have an expected lifetime of five to eight years during which very little wear of the components is acceptable. Too much wear compromises the dosage accuracy of the device and thereby...... the safety of the patients. Prediction of the wear of polymers is complicated by the low thermal conductivity of this kind of material. It implies that any acceleration of testing conditions by increased contact pressure and/or sliding velocity will make the polymer fail due to exaggerated heat buildup....... This is not the kind of wear observed in medical devices. In the present work a method was developed capable of evaluating the wear progression in polymer-polymer contacts. The configuration of the setup is injection moulded specimens consisting of an upper part having a toroid shape and a lower flat part. The sliding...

  6. Wear mechanism for spray deposited Al-Si/SiCp composites under dry sliding condition

    Institute of Scientific and Technical Information of China (English)

    滕杰; 李华培; 陈刚

    2015-01-01

    Al-Si/15%SiCp (volume fraction) composites with different silicon contents were fabricated by spray deposition technique, and typical microstructures of these composites were studied by optical microscopy (OM). Dry sliding wear tests were carried out using a block-on-ring wear machine to investigate the effect of applied load range of 10−220 N on the wear and friction behavior of these composites sliding against SAE 52100 grade bearing steel. Scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX) were utilized to examine the morphologies of the worn surfaces in order to observe the wear characteristics and investigate the wear mechanism. The results show that the wear behavior of these composites is dependent on the silicon content in the matrix alloy and the applied load. Al-Si/15%SiCp composites with higher silicon content exhibit better wear resistance in the applied load range. Under lower loads, the major wear mechanisms are oxidation wear and abrasive wear for all tested composites. Under higher loads, severe adhesive wear becomes the main wear mechanisms for Al-7Si/15%SiCp and Al-13Si/15%SiCp composites, while Al-20Si/15%SiCp presents a compound wear mechanism, consisting of oxidation, abrasive wear and adhesion wear.

  7. Experimental and theoretical studies of scuffing behavior in piston-pin/piston contacts

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A bench rig was built and used to study the scuffing mechanisms and the effects of sur-face roughness, clearance, and groove on scuffing in piston-pin/bore contacts for dynamic loadsand an oscillatory rotation. The experimental results show that the deterioration of the surfaceshear strength by fatigue cracks appears to contribute to the final scuffing, and the effects of thebore surface roughness and groove on the scuffing behavior are more significant than the clear-ance. A macro-micro approached scuffing model and a criterion for scuffing failure were developedappearing to be justifiable for the practical design and analysis of piston pin/bore bearings.

  8. Improving Free-Piston Stirling Engine Power Density

    Science.gov (United States)

    Briggs, Maxwell H.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58% using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a maximum piston power increase of 14%. Analytical predictions are compared to experimental data showing close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  9. Improving Power Density of Free-Piston Stirling Engines

    Science.gov (United States)

    Briggs, Maxwell H.; Prahl, Joseph M.; Loparo, Kenneth A.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free-piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58 percent using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a piston power increase of as much as 14 percent. Analytical predictions are compared to experimental data and show close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  10. Improving Free-Piston Stirling Engine Specific Power

    Science.gov (United States)

    Briggs, Maxwell H.

    2015-01-01

    This work uses analytical methods to demonstrate the potential benefits of optimizing piston and/or displacer motion in a Stirling engine. Isothermal analysis was used to show the potential benefits of ideal motion in ideal Stirling engines. Nodal analysis is used to show that ideal piston and displacer waveforms are not optimal in real Stirling engines. Constrained optimization was used to identify piston and displacer waveforms that increase Stirling engine specific power.

  11. Internal position and limit sensor for free piston machines

    Science.gov (United States)

    Holliday, Ezekiel S. (Inventor); Wood, James Gary (Inventor)

    2012-01-01

    A sensor for sensing the position of a reciprocating free piston in a free piston Stirling machine. The sensor has a disk mounted to an end face of the power piston coaxially with its cylinder and reciprocating with the piston The disk includes a rim around its outer perimeter formed of an electrically conductive material A coil is wound coaxially with the cylinder, spaced outwardly from the outer perimeter of the disk and mounted in fixed position relative to the pressure vessel, preferably on the exterior of the pressure vessel wall.

  12. Optimization of image capturing method of wear particles for condition diagnosis of machine parts

    Institute of Scientific and Technical Information of China (English)

    Yon-Sang CHO; Heung-Sik PARK

    2009-01-01

    Wear particles are inevitably occurred from moving parts, such as a piston-cylinder made from steel or hybrid materials. And a durability of these parts must be evaluated. The wear particle analysis has been known as a very effective method to foreknow and decide a moving situation and a damage of machine parts by using the digital computer image processing. But it is not laid down to calculate shape parameters of wear particle and wear volume. In order to apply image processing method in a durability evaluation of machine parts, it needs to verify the reliability of the calculated data by the image processing and to lay down the number of images and the amount of wear particles in one image. In this work, the lubricated friction experiment was carried out in order to establish the optimum image capture with the 1045 specimen under experiment condition. The wear particle data were calculated differently according to the number of image and the amount of wear particle in one image. The results show that capturing conditions need to he more than 140 wear particles in one image and over 40 images for the reliable data. Thus, the capturing method of wear particles images was optimized for condition diagnosis of machine moving parts.

  13. Fluid dynamic modeling of a free piston engine with labyrinth seals

    Science.gov (United States)

    Larjola, Jaakko; Honkatukia, Juha; Sallinen, Petri; Backman, Jari

    2010-04-01

    Preliminary design and simulation of a free piston engine suitable for small-scale energy production in distributed energy systems is presented in this paper. The properties, particularly the properties of gas seals of the engine are simulated using a simulation program developed for this case, and the results are utilized in preliminary main design parameter selection. The engine simulation program was developed by combining and modifying the source codes of the simulation and calculation programs obtained from Helsinki University of Technology, Tampere University of Technology, and Lappeenranta University of Technology. Because of the contact-free labyrinth seal used in the piston, the efficiency of the motor is lower than the efficiency of a conventional motor with oil lubricated piston rings. On the other hand, the lack of bearing losses, and the lack of losses associated with a crankshaft system and a gearbox, as well as the lack of lubrication oil expenses, compensates this effect. As a net result, this new motor would perform slightly better than the conventional one. Being completely oil-free, it is very environmentally friendly, and its exhaust gases are completely free of oil residuals which are causing problems in normal gas motors.

  14. Polyethylene sterilization and production affects wear in total hip arthroplasties.

    Science.gov (United States)

    Faris, Philip M; Ritter, Merrill A; Pierce, Andrew L; Davis, Kenneth E; Faris, Gregory W

    2006-12-01

    Production and package sterilization techniques for the polyethylene used in acetabular components for total hip arthroplasties are known to affect wear. We considered three combinations of techniques: sterilization by radiation in inert gas with isostatically molded polyethylene, in inert gas and ram-extruded polyethylene, and in air with extruded polyethylene. The intent of this study was to confirm that molded polyethylene and polyethylene radiated in inert environments reduce wear rates in vivo, to determine the combination of methods with the least wear, and to determine how much variance in wear is attributable to these methods. We reviewed 150 consecutive total hip arthroplasties done in 133 patients using 28-mm cobalt-chrome femoral heads and polyethylene-lined, titanium, ring-locked acetabular components. The least wear occurred in gamma inert-molded polyethylene components. The mean volumetric wear rates were 52.12 mm3/year for gamma inert-molded, 62.32 mm3/year for gamma inert-extruded, and 66.09 mm3/year for gamma air-extruded polyethylene components. Relative risk assessment found gamma air-extruded and gamma inert-extruded polyethylene components to wear 16% and 11% more than gamma inert-molded polyethylene components, respectively. Gender, body mass index, and age accounted for the greatest amount of the explained variance in volumetric wear (57.5%, 21.6%, and 14.4, respectively), followed by angle of wear (3.4%), and sterilization and production technique (3.2%).

  15. DESIGN AND CONSTRUCTION OF A HYDRAULIC PISTON

    OpenAIRE

    Santos De La Cruz, Eulogio; Universidad Nacional Mayor de San Marcos; Rojas Lazo, Oswaldo; Universidad Nacional Mayor de San Marcos; Yenque Dedios, Julio; Universidad Nacional Mayor de San Marcos; Lavado Soto, Aurelio; Universidad Nacional Mayor de San Marcos

    2014-01-01

    A hydraulic system project includes the design, materials selection and construction of the hydraulic piston, hydraulic circuit and the joint with the pump and its accesories. This equiment will be driven by the force of moving fluid, whose application is in the devices of machines, tools, printing, perforation, packing and others. El proyecto de un sistema hidráulico, comprende el diseño, selección de materiales y construcción del pistón hidráulico, circuito hidráulico y el ensamble con l...

  16. Free Piston Double Diaphragm Shock Tube

    OpenAIRE

    OGURA, Eiji; FUNABIKI, Katsushi; SATO, Shunichi; Abe, Takashi; 小倉, 栄二; 船曳, 勝之; 佐藤, 俊逸; 安部, 隆士

    1997-01-01

    A free piston double diaphragm shock tube was newly developed for generation of high Mach number shock wave. Its characteristics was investigated for various operation parameters; such as a strength of the diaphragm at the end of the comparession tube, an initial pressure of low pressure tube, an initial pressure of medium pressure tube and the volume of compression tube. Under the restriction of fixed pressures for the driver high pressure tube (32×10^5Pa) and the low pressure tube (40Pa) in...

  17. Manually operated piston-driven shock tube

    OpenAIRE

    Reddy, KPJ; Sharath, N

    2013-01-01

    A simple hand-operated shock tube capable of producing Mach 2 shock waves is described. Performance of this miniature shock tube using compressed high pressure air created by a manually operated piston in the driver section of the shock tube as driver gas with air at 1 atm pressure as the test gas in the driven tube is presented. The performance of the shock tube is found to match well with the theoretically estimated values using normal shock relations. Applications of this shock tube named ...

  18. Stability analysis of free piston Stirling engines

    Science.gov (United States)

    Bégot, Sylvie; Layes, Guillaume; Lanzetta, François; Nika, Philippe

    2013-03-01

    This paper presents a stability analysis of a free piston Stirling engine. The model and the detailed calculation of pressures losses are exposed. Stability of the machine is studied by the observation of the eigenvalues of the model matrix. Model validation based on the comparison with NASA experimental results is described. The influence of operational and construction parameters on performance and stability issues is exposed. The results show that most parameters that are beneficial for machine power seem to induce irregular mechanical characteristics with load, suggesting that self-sustained oscillations could be difficult to maintain and control.

  19. WEAR AND SEALING CHARACTERISTICS OF ENGINE VALVE GUIDE

    Institute of Scientific and Technical Information of China (English)

    Qu Shengguan; Xia Wei; Han Lifa; Xiao Zhiyu; Chen Weiping; Li Yuanyuan

    2005-01-01

    A novel powder metallurgy (P/M) material with high wear resistance is developed in order to decrease the wear and lubricant-leakage of a diesel engine valve guide. The friction and wear tests of this material are conducted. It indicates that the wear resistance of the newly developed P/M material has been improved and much better than that of the formerly used alloy steel. Moreover, three different sealing structures are designed and theoretically analyzed with respect to the characteristic of hydrodynamic sealing. Through comparative experiments of component leakage and engine run-in for different valve guide structures, it proves that the structure with a machined sealing groove but not installed with a seal-ring cannot only reduce the specific lubricant consumption (SLC) of cylinder head, but also decrease the wear of valve stem and valve guide.

  20. LINC-NIRVANA piston control elements

    Science.gov (United States)

    Brix, Mario; Pott, Jörg-Uwe; Bertram, Thomas; Rost, Steffen; Borelli, Jose Luis; Herbst, Thomas M.; Kuerster, Martin; Rohloff, Ralf-Rainer

    2010-07-01

    We review the status of hardware developments related to the Linc-Nirvana optical path difference (OPD) control. The status of our telescope vibration measurements is given. We present the design concept of a feed-forward loop to damp the impact of telescope mirror vibrations on the OPD seen by Linc-Nirvana. At the focus of the article is a description of the actuator of the OPD control loop. The weight and vibration optimized construction of this actuator (aka piston mirror) and its mount has a complex dynamical behavior, which prevents classical PI feedback control from delivering fast and precise motion of the mirror surface. Therefore, an H-; optimized control strategy will be applied, custom designed for the piston mirror. The effort of realizing a custom controller on a DSP to drive the piezo is balanced by the outlook of achieving more than 5x faster servo bandwidths. The laboratory set-up to identify the system, and verify the closed loop control performance is presented. Our goal is to achieve 30 Hz closed-loop control bandwidth at a precision of 30 nm.

  1. Fluid powered linear piston motor with harmonic coupling

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, David W.

    2016-09-20

    A motor is disclosed that includes a module assembly including a piston that is axially cycled. The piston axial motion is coupled to torque couplers that convert the axial motion into rotary motion. The torque couplers are coupled to a rotor to rotate the rotor.

  2. Entropic Damping of the Motion of a Piston

    Science.gov (United States)

    Mungan, Carl E.

    2017-01-01

    The concept of an "entropic force" can be introduced by considering a familiar setup, namely a horizontal cylinder enclosing an ideal monatomic gas by a piston of cross-sectional area "A" and mass "m" that can slide without friction. The surrounding atmospheric pressure P[subscript atm] keeps the piston from flying…

  3. Entropic Damping of the Motion of a Piston

    Science.gov (United States)

    Mungan, Carl E.

    2017-03-01

    The concept of an "entropic force" can be introduced by considering a familiar setup, namely a horizontal cylinder enclosing an ideal monatomic gas by a piston of cross-sectional area A and mass m that can slide without friction. The surrounding atmospheric pressure Patm keeps the piston from flying out of the cylinder. The cylinder and piston have negligible heat capacity (compared to the gas), but the gas is not thermally insulated from the surroundings at room temperature TR. Ignore any viscosity or turbulence of the enclosed gas or surrounding air. Two specific and illustrative situations are analyzed here. In the first, the piston is massless, m = 0. The piston is temporarily held in place by a pin while the gas is quickly adjusted to initial pressure Pi = Patm and temperature slightly larger than that of the room, say Ti = 1.1TR, using a heater and regulator. The piston is then released from rest, vi = 0. In the second case, the piston has inertia, m > 0, and the gas is initially in both mechanical and thermal equilibrium with the surroundings so that Pi = Patm and Ti = TR. The piston is now given a quick inward push, vi < 0. In both situations, the aim is the same: Describe the subsequent evolution of the system.

  4. Reduction of HCCI combustion noise through piston crown design

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper

    2010-01-01

    Seven shapes of piston crowns have been evaluated for their ability to reduce HCCI knock and transmission of combustion noise to the engine. The performance of each piston crown was evaluated with measurements of cylinder pressure, engine vibration and acoustic sound pressure measured one meter a...

  5. Vascular ring

    Science.gov (United States)

    ... subclavian and left ligamentum ateriosus; Congenital heart defect - vascular ring; Birth defect heart - vascular ring ... Vascular ring is rare. It accounts for less than 1% of all congenital heart problems. The condition ...

  6. Piston motion in the perfect-conductive magnetizable uncompressible fluid

    Energy Technology Data Exchange (ETDEWEB)

    Naletova, V.A.

    1977-01-01

    A solution is given for the movement of a perfect conductive solid horizontal piston at a constant velocity u, parallel to the plane of the piston, in a perfect conductive magnetizable uncompressible fluid in an applied magnetic field H/sub 0/. Either a shock wave, a centered wave, or a alvenian fracture, or a combination of an alvenian fracture and waves can be propagated in front of the piston under these conditions. In this case either the shock or centered wave is propagated at first, followed by the movement of the alvenian fracture. Either case is manifested at such velocities. When the piston moves along the boundary, the piston-medium can flow as a surface current which can be found from the solution to the problem. 3 references, 3 figures.

  7. 一种旋转扁圆活塞压缩机%A Type of Rotary Oblate Piston Compressor

    Institute of Scientific and Technical Information of China (English)

    李东林

    2013-01-01

    分析了往复活塞式、滑片式(回转式)等压缩机的结构特点,着重找出了存在缺陷的原因;本设计中将往复直线运动的圆柱体活塞优化为可绕圆环形气缸圆心转动、外端是圃曲面形状的扁圆体活塞,使往复运动的活塞真正转了起来,消除了往复惯性,减少了零部件,是一种全新结构的压缩机,具有较好的发展前景.%The paper analyzes the structural features of reciprocating piston, sliding (rotating) compressors, and finds the causes of the bug.The cylinder piston with reciprocating line movement has been optimized ring cylinder spinning with outer curved flat circular piston,which resulted in real reciprocating piston spinning,getting rid of inertia,and decreasing parts.This is a totally new structured compressor with its better development.

  8. Mechanical and biomechanical analysis of a linear piston design for angular-velocity-based orthotic control

    Directory of Open Access Journals (Sweden)

    Edward D. Lemaire, PhD

    2013-02-01

    Full Text Available A linear piston hydraulic angular-velocity-based control knee joint was designed for people with knee-extensor weakness to engage knee-flexion resistance when knee-flexion angular velocity reaches a preset threshold, such as during a stumble, but to otherwise allow free knee motion. During mechanical testing at the lowest angular-velocity threshold, the device engaged within 2 degrees knee flexion and resisted moment loads of over 150 Nm. The device completed 400,000 loading cycles without mechanical failure or wear that would affect function. Gait patterns of nondisabled participants were similar to normal at walking speeds that produced below-threshold knee angular velocities. Fast walking speeds, employed purposely to attain the angular-velocity threshold and cause knee-flexion resistance, reduced maximum knee flexion by approximately 25 degrees but did not lead to unsafe gait patterns in foot ground clearance during swing. In knee collapse tests, the device successfully engaged knee-flexion resistance and stopped knee flexion with peak knee moments of up to 235.6 Nm. The outcomes from this study support the potential for the linear piston hydraulic knee joint in knee and knee-ankle-foot orthoses for people with lower-limb weakness.

  9. Mechanical and biomechanical analysis of a linear piston design for angular-velocity-based orthotic control.

    Science.gov (United States)

    Lemaire, Edward D; Samadi, Reza; Goudreau, Louis; Kofman, Jonathan

    2013-01-01

    A linear piston hydraulic angular-velocity-based control knee joint was designed for people with knee-extensor weakness to engage knee-flexion resistance when knee-flexion angular velocity reaches a preset threshold, such as during a stumble, but to otherwise allow free knee motion. During mechanical testing at the lowest angular-velocity threshold, the device engaged within 2 degrees knee flexion and resisted moment loads of over 150 Nm. The device completed 400,000 loading cycles without mechanical failure or wear that would affect function. Gait patterns of nondisabled participants were similar to normal at walking speeds that produced below-threshold knee angular velocities. Fast walking speeds, employed purposely to attain the angular-velocity threshold and cause knee-flexion resistance, reduced maximum knee flexion by approximately 25 degrees but did not lead to unsafe gait patterns in foot ground clearance during swing. In knee collapse tests, the device successfully engaged knee-flexion resistance and stopped knee flexion with peak knee moments of up to 235.6 Nm. The outcomes from this study support the potential for the linear piston hydraulic knee joint in knee and knee-ankle-foot orthoses for people with lower-limb weakness.

  10. Composite ceramic/metal piston assembly and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Hartsock, D.L.

    1987-03-17

    This patent describes an integrally cast composite assembly of a cylindrical cap attached to a piston having a higher thermal expansion characteristic than the cylindrical cap, the cap being adapted to receive a ceramic insert, comprising: (a) a piston body comprised substantially as a body of revolution about an axis and comprised of a material having a higher thermal expansion characteristic than the cylindrical cap. The piston body has a crown top and an annular crown side wall with an upper edge, and an annular undercut surface terminating the crown side wall. The undercut surface makes an angle with a plane extending perpendicular to the axis and passing through the upper edge of the crown side wall. The angle is substantially equal to the arc tangent of H/R where H is the median distance of the undercut surface from the plane and R is the median radius fo the undercut surface from the axis of the piston; and (b) a cylindrical cap disposed on the piston crown top and having a cap side wall depending about the crown side wall, the cap side wall having an annular lip extending radially inwardly from the cap side wall. The lip has surface mateable with the undercut surface of the piston body so that there exists a tightly stressed camming relationship between the mateable surfaces as a result of the shrinkage of the piston body upon solidification.

  11. Ring blowers. Ring blower

    Energy Technology Data Exchange (ETDEWEB)

    Nakahara, Y.; Okamura, T.; Takahashi, M. (Fuji Electric Co. Ltd., Tokyo (Japan))

    1991-06-10

    Features, structures and several products of ring blowers were outlined. The ring blower is featured by its medium characteristics because it is higher in air pressure than a turboblower and larger in airflow than a vane blower, and it is applicable flexibly to not only air blasting but various industrial fields such as suction transfer. As several products corresponding to various fields, the followings were outlined: the low noise type with optimum shapes of inlet, outlet and casing cover for reducing noises by 10 dB or more, the heat resistant, water-tight and explosion-proof types suitable for severe environmental conditions, the multi-voltage type for every country served at different voltages, the high air pressure type with two pressure rise stages, and the large airflow type with a wide impeller. In addition, as special use products, the glass fiber reinforced unsatulated polyester ring blower for respiration apparatus, and the variable speed blushless DC motor-driven one for medical beds were outlined. 2 refs., 9 figs., 1 tab.

  12. Piston diameter in stapes surgery. Does it have a bearing?

    Directory of Open Access Journals (Sweden)

    Neha Gupta

    2014-01-01

    Full Text Available Aims and Objectives: This prospective randomized controlled trial was done to study the effect of piston diameter on hearing outcomes after stapedotomy. Materials and Methods: All the patients diagnosed to have otosclerosis were included in the study. A total of 52 patients were studied ranging in age from 18 to 50 years. The subjects were randomized into two groups, that is, 0.4 mm piston (group A and 0.6 mm piston (group B. The subjects were taken up for small fenestra stapedotomy using either a 0.4 or 0.6 mm piston. The main outcome measures were hearing improvement, air-bone gap closure, and overclosure of air-bone gap. Results: There was no statistical difference in hearing improvement in two different piston diameters, 0.4 and 0.6 mm at speech frequencies. In group A, the air-bone gap improvement in the third follow-up was not significant (P > 0.05, whereas group B showed a statistically significant improvement (P = 0.003. The mean overclosure of air-bone gap was better in patients with 0.4 mm piston at speech frequencies and also at 250 Hz. Significantly, overclosure of air-bone gap at higher frequencies (4 and 8 KHz was seen only with a smaller sized piston. (0.4 mm. Discussion: We analyzed the effect of piston diameter on the hearing results after small fenestra stapedotomy by using similar surgical procedure and similar prosthesis in all patients. Conclusion: There is evidence to suggest that 0.4 mm piston may be better suited for providing optimum hearing results.

  13. 润滑油中加入纳米氧化铝对缸套-活塞环摩擦副摩擦磨损特性的影响%Effect of Nano-Al2O3 in Lubricating Oil on the Characteristics of Wear and Friction of Cylinder Liner /Piston ring Rubbing Pair of Diesel Engine

    Institute of Scientific and Technical Information of China (English)

    韩德宝; 关德林; 宋希庚

    2006-01-01

    在普通CD40润滑油中加入纳米氧化铝,研究了在不同载荷条件下对缸套活塞环摩擦副摩擦磨损特性的影响;用铁谱仪对试验油样进行了磨粒分析;用原子力显微镜对缸套试样表面的微观形貌进行了测试;用LAS-3000型表面分析系统对磨损表面进行了成分分析.结果表明:缸套活塞环摩擦副在含纳米氧化铝的润滑油作用下,表现出优越的抗摩减磨性能,其效果随载荷的增大而增强;在高载荷作用下缸套试样表面形貌有了明显的改观,减小了摩擦阻力,降低了摩擦因数.

  14. Loss terms in free-piston Stirling engine models

    Science.gov (United States)

    Gordon, Lloyd B.

    1992-01-01

    Various models for free piston Stirling engines are reviewed. Initial models were developed primarily for design purposes and to predict operating parameters, especially efficiency. More recently, however, such models have been used to predict engine stability. Free piston Stirling engines have no kinematic constraints and stability may not only be sensitive to the load, but also to various nonlinear loss and spring constraints. The present understanding is reviewed of various loss mechanisms for free piston Stirling engines and how they have been incorporated into engine models is discussed.

  15. Reversible compression of an optical piston through Kramers dynamics

    CERN Document Server

    Schnoering, Gabriel

    2015-01-01

    We study the reversible crossover between stable and bistable phases of an over-damped Brownian bead inside an optical piston. The interaction potentials are solved developing a method based on Kramers' theory that exploits the statistical properties of the stochastic motion of the bead. We evaluate precisely the energy balance of the crossover. We show that the deformation of the optical potentials induced by the compression of the piston is related to a production of heat which measures the non-adiabatic character of the crossover. This reveals how specific thermodynamic processes can be designed and controlled with a high level of precision by tailoring the optical landscapes of the piston.

  16. 柴油机活塞敲击及其振动响应机理研究%Piston Slap and Its Vibration Response Mechanism of Diesel Engine

    Institute of Scientific and Technical Information of China (English)

    李晓磊; 刘建敏; 乔新勇; 李晓伟; 张杰

    2014-01-01

    以某12150柴油机为研究对象,通过分析活塞的受力情况,建立了活塞敲击的动力学模型;完成了柴油机台架试验,并同步采集了缸内压力及机体振动信号;通过分析机体振动信号的时频特性及柴油机工作时序验证了敲击模型的准确性;基于此模型,分别研究了柴油机转速、负荷、温度以及活塞装配间隙对活塞敲击时刻及敲击动能的影响,揭示了活塞敲击激励与活塞装配间隙及转速等因素的本质联系,为利用振动信号监测缸套磨损状况提供了理论基础。%The dynamic model of piston slap for a 12150 diesel engine was built by analyzing the stress of piston .Based on the bench test of diesel engine ,the in-cylinder pressure and body vibration signals were collected .The accuracy of slap model was verified according to the time-frequency characteristic of body vibration signal and diesel engine operating sequence .With the model ,the influences of engine speed ,load ,temperature and piston fit-up gap on piston slap timing and slap kinetic energy were researched .Finally ,the relations between the piston slap excitation and the piston fit-up gap as well as engine speed were revealed ,which brought the theoretical basis for monitoring the liner wear with the vibration signal .

  17. High Temperature Dry Sliding Friction and Wear Performance of Laser Cladding WC/Ni Composite Coating

    Directory of Open Access Journals (Sweden)

    YANG Jiao-xi

    2016-06-01

    Full Text Available Two different types of agglomerate and angular WC/Ni matrix composite coatings were deposited by laser cladding. The high temperature wear resistance of these composite coatings was tested with a ring-on-disc MMG-10 apparatus. The morphologies of the worn surfaces were observed using a scanning electron microscopy (SEM equipped with an energy dispersive spectroscopy (EDS for elemental composition. The results show that the high temperature wear resistance of the laser clad WC/Ni-based composite coatings is improved significantly with WC mass fraction increasing. The 60% agglomerate WC/Ni composite coating has optimal high temperature wear resistance. High temperature wear mechanism of 60% WC/Ni composite coating is from abrasive wear of low temperature into composite function of the oxidation wear and abrasive wear.

  18. Optical wear monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Kidane, Getnet S; Desilva, Upul P.; He, Chengli; Ulerich, Nancy H.

    2016-07-26

    A gas turbine includes first and second parts having outer surfaces located adjacent to each other to create an interface where wear occurs. A wear probe is provided for monitoring wear of the outer surface of the first part, and includes an optical guide having first and second ends, wherein the first end is configured to be located flush with the outer surface of the first part. A fiber bundle includes first and second ends, the first end being located proximate to the second end of the optical guide. The fiber bundle includes a transmit fiber bundle comprising a first plurality of optical fibers coupled to a light source, and a receive fiber bundle coupled to a light detector and configured to detect reflected light. A processor is configured to determine a length of the optical guide based on the detected reflected light.

  19. Saturn's Rings

    Science.gov (United States)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  20. Experimental Evaluation of the Free Piston Engine - Linear Alternator (FPLA)

    Energy Technology Data Exchange (ETDEWEB)

    Leick, Michael T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moses, Ronald W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    This report describes the experimental evaluation of a prototype free piston engine - linear alternator (FPLA) system developed at Sandia National Laboratories. The opposed piston design wa developed to investigate its potential for use in hybrid electric vehicles (HEVs). The system is mechanically simple with two - stroke uniflow scavenging for gas exchange and timed port fuel injection for fuel delivery, i.e. no complex valving. Electrical power is extracted from piston motion through linear alternators wh ich also provide a means for passive piston synchronization through electromagnetic coupling. In an HEV application, this electrical power would be used to charge the batteries. The engine - alternator system was designed, assembled and operated over a 2 - year period at Sandia National Laboratories in Livermore, CA. This report primarily contains a description of the as - built system, modifications to the system to enable better performance, and experimental results from start - up, motoring, and hydrogen combus tion tests.

  1. Multiple Scattering: Dispersion, Temperature Dependence, and Annular Pistons

    CERN Document Server

    Milton, Kimball A; Parashar, Prachi; Cavero-Pelaez, Ines; Brevik, Iver; Ellingsen, Simen A

    2010-01-01

    We review various applications of the multiple scattering approach to the calculation of Casimir forces between separate bodies, including dispersion, wedge geometries, annular pistons, and temperature dependence. Exact results are obtained in many cases.

  2. Experimental Evaluation of the Free Piston Engine - Linear Alternator (FPLA).

    Energy Technology Data Exchange (ETDEWEB)

    Leick, Michael T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moses, Ronald W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    This report describes the experimental evaluation of a prototype free piston engine - linear alternator (FPLA) system developed at Sandia National Laboratories. The opposed piston design wa developed to investigate its potential for use in hybrid electric vehicles (HEVs). The system is mechanically simple with two - stroke uniflow scavenging for gas exchange and timed port fuel injection for fuel delivery, i.e. no complex valving. Electrical power is extracted from piston motion through linear alternators wh ich also provide a means for passive piston synchronization through electromagnetic coupling. In an HEV application, this electrical power would be used to charge the batteries. The engine - alternator system was designed, assembled and operated over a 2 - year period at Sandia National Laboratories in Livermore, CA. This report primarily contains a description of the as - built system, modifications to the system to enable better performance, and experimental results from start - up, motoring, and hydrogen combus tion tests.

  3. Dynamics of a massive piston in an ideal gas

    Energy Technology Data Exchange (ETDEWEB)

    Chernov, N I [University of Alabama at Birmingham, Birmingham, Alabama (United States); Lebowitz, J L [Rutgers, State University of New Jersey, New Brunswick, NJ (United States); Sinai, Yakov G [L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, Moscow (Russian Federation)

    2002-12-31

    This survey is a study of a dynamical system consisting of a massive piston in a cubic container of large size L filled with an ideal gas. The piston has mass M{approx}L{sup 2} and undergoes elastic collisions with N{approx}L{sup 3} non-interacting gas particles of mass m=1. It is found that under suitable initial conditions there is a scaling regime with time and space scaled by L in which the motion of the piston and the one-particle distribution of the gas satisfy autonomous coupled equations (hydrodynamic equations) such that in the limit L{yields}{infinity} the mechanical trajectory of the piston converges in probability to the solution of the hydrodynamic equations for a certain period of time. There is also a heuristic discussion of the dynamics of the system on longer intervals of time.

  4. Structural design of Stirling engine with free pistons

    Science.gov (United States)

    Matusov, Jozef; Gavlas, Stanislav; Malcho, Milan

    2014-08-01

    Stirling engine is a device that converts thermal energy to mechanical work, which is mostly used to drive a generator of electricity. Advantage of Stirling engine is that it works with closed-cycle, where working medium is regularly cooled and heated, which acts on the working piston. This engine can be made in three modifications - alpha, beta, gamma. This paper discusses the design of the gamma Stirling engine with free pistons.

  5. Gas Vapor Injection on Refrigerant Cycle Using Piston Technology

    OpenAIRE

    Colmek, Sophie; Goderneaux, Laurent

    2012-01-01

    Gas vapor injection on refrigerant cycle is always used with Scroll, Rotary or others compressors technology to improve efficiency of the system at low and high ambient temperatures. Probably this kind of compressor is more adapted than the piston technology owing to their mechanical system. In this paper, we present the challenge of vapor injection realized on piston technology compressor range non for improving the cooling capacity of the system but to maintain the compressor temperature in...

  6. Three dimensional Casimir piston for massive scalar fields

    CERN Document Server

    Lim, S C

    2008-01-01

    We consider Casimir force acting on a three dimensional rectangular piston due to a massive scalar field subject to periodic, Dirichlet and Neumann boundary conditions. Exponential cut-off method is used to derive the Casimir energy in the interior region and the exterior region separated by the piston. It is shown that the divergent term of the Casimir force acting on the piston due to the interior region cancels with that due to the exterior region, thus render a finite well-defined Casimir force acting on the piston. Explicit expressions for the total Casimir force acting on the piston is derived, which show that the Casimir force is always attractive for all the different boundary conditions considered. As a function of a -- the distance from the piston to the opposite wall, it is found that the magnitude of the Casimir force behaves like $1/a^4$ when $a\\to 0^+$ and decays exponentially when $a\\to \\infty$. Moreover, the magnitude of the Casimir force is always a decreasing function of a. On the other hand...

  7. Fluid Dynamics in Rotary Piston Blood Pumps.

    Science.gov (United States)

    Wappenschmidt, Johannes; Sonntag, Simon J; Buesen, Martin; Gross-Hardt, Sascha; Kaufmann, Tim; Schmitz-Rode, Thomas; Autschbach, Ruediger; Goetzenich, Andreas

    2017-03-01

    Mechanical circulatory support can maintain a sufficient blood circulation if the native heart is failing. The first implantable devices were displacement pumps with membranes. They were able to provide a sufficient blood flow, yet, were limited because of size and low durability. Rotary pumps have resolved these technical drawbacks, enabled a growing number of mechanical circulatory support therapy and a safer application. However, clinical complications like gastrointestinal bleeding, aortic insufficiency, thromboembolic complications, and impaired renal function are observed with their application. This is traced back to their working principle with attenuated or non-pulsatile flow and high shear stress. Rotary piston pumps potentially merge the benefits of available pump types and seem to avoid their complications. However, a profound assessment and their development requires the knowledge of the flow characteristics. This study aimed at their investigation. A functional model was manufactured and investigated with particle image velocimetry. Furthermore, a fluid-structure interaction computational simulation was established to extend the laboratory capabilities. The numerical results precisely converged with the laboratory measurements. Thus, the in silico model enabled the investigation of relevant areas like gap flows that were hardly feasible with laboratory means. Moreover, an economic method for the investigation of design variations was established.

  8. Visceral-locomotory pistoning in crawling caterpillars.

    Science.gov (United States)

    Simon, Michael A; Woods, William A; Serebrenik, Yevgeniy V; Simon, Sharotka M; van Griethuijsen, Linnea I; Socha, John J; Lee, Wah-Keat; Trimmer, Barry A

    2010-08-24

    Animals with an open coelom do not fully constrain internal tissues, and changes in tissue or organ position during body movements cannot be readily discerned from outside of the body. This complicates modeling of soft-bodied locomotion, because it obscures potentially important changes in the center of mass as a result of internal tissue movements. We used phase-contrast synchrotron X-ray imaging and transmission light microscopy to directly visualize internal soft-tissue movements in freely crawling caterpillars. Here we report a novel visceral-locomotory piston in crawling Manduca sexta larvae, in which the gut slides forward in advance of surrounding tissues. The initiation of gut sliding is synchronous with the start of the terminal prolegs' swing phase, suggesting that the animal's center of mass advances forward during the midabdominal prolegs' stance phase and is therefore decoupled from visible translations of the body. Based on synchrotron X-ray data and transmission light microscopy results, we present evidence for a two-body mechanical system with a nonlinear elastic gut that changes size and translates between the anterior and posterior of the animal. The proposed two-body system--the container and the contained--is unlike any form of legged locomotion previously reported and represents a new feature in our emerging understanding of crawling.

  9. Vortex rings

    Energy Technology Data Exchange (ETDEWEB)

    Akhmetov, D.G. [Lavrentiev Institute of Hydrodynamics, Novosibirsk (Russian Federation)

    2009-07-01

    This book presents a comprehensive coverage of the wide field of vortex rings. The book presents the results of systematic experimental investigations, theoretical foundation, as well as the practical applications of vortex rings, such as the extinction of fires at gushing gas and oil wells. All the basic properties of vortex rings as well as their hydrodynamic structures are presented. Special attention is paid to the formation and motion of turbulent vortex rings. (orig.)

  10. The linear stability of swirling vortex rings

    Science.gov (United States)

    Gargan-Shingles, C.; Rudman, M.; Ryan, K.

    2016-11-01

    The stability of vortex rings with an azimuthal component of velocity is investigated numerically for various combinations of ring wavenumber and swirl magnitude. The vortex rings are equilibrated from an initially Gaussian distribution of azimuthal vorticity and azimuthal velocity, at a circulation-based Reynolds number of 10 000, to a state in which the vortex core is qualitatively identical to that of the piston generated vortex rings. The instability modes of these rings can be characterised as Kelvin instability modes, analogous to instability modes observed for Gaussian and Batchelor vortex pairs. The shape of an amplified mode typically depends only on the azimuthal wavenumber at the centre of the vortex core and the magnitude of the corresponding velocity component. The wavenumber of a particular sinuous instability varies with radius from the vortex ring centre for rings of finite aspect ratio. Thicker rings spread the amplification over a wider range of wavenumbers for a particular resonant mode pair, while the growth rate and the azimuthal wavenumber corresponding to the peak growth both vary as a function of the wavenumber variation. Normalisation of the wavenumber and the growth rate by a measure of the wavenumber variation allows a coherent description of stability modes to be proposed, across the parameter space. These results provide a framework for predicting the development of resonant Kelvin instabilities on vortex rings with an induced component of swirling velocity.

  11. Comparative wear mapping techniques

    DEFF Research Database (Denmark)

    Alcock, J.; Sørensen, Ole Toft; Jensen, S.

    1996-01-01

    Pin surfaces were analysed by laser profilometry. Two roughness parameters, R(a) and the fractal dimension, were investigated as a first step towards methods of quantitative wear mechanism mapping. Both parameters were analysed for their relationship to the severity and prevalence of a mechanism....

  12. Assessment of wear facets produced by the ACTA wear machine

    DEFF Research Database (Denmark)

    Benetti, Ana R; Larsen, Liselotte; Dowling, Adam H

    2016-01-01

    OBJECTIVE: To investigate the use of a three-dimensional (3D) digital scanning method in determining the accuracy of the wear performance parameters of resin-based composites (RBCs) determined using a two-dimensional (2D) analogue methodology following in-vitro testing in an Academisch Centrum...... an assessment of the potential of the experimental RBC formulations for clinical usage. CONCLUSION: The 3D technique allowed for the assessment of mean maximum wear depth and mean total volumetric wear which enables tribological analyses of the wear facet and therefore the wear mechanisms operative. Employing...... profilers is useful when screening potential new RBC formulations for the restoration of posterior dentition....

  13. Ring theory

    CERN Document Server

    Rowen, Louis H

    1991-01-01

    This is an abridged edition of the author's previous two-volume work, Ring Theory, which concentrates on essential material for a general ring theory course while ommitting much of the material intended for ring theory specialists. It has been praised by reviewers:**""As a textbook for graduate students, Ring Theory joins the best....The experts will find several attractive and pleasant features in Ring Theory. The most noteworthy is the inclusion, usually in supplements and appendices, of many useful constructions which are hard to locate outside of the original sources....The audience of non

  14. Preliminary results from a four-working space, double-acting piston, Stirling engine controls model

    Science.gov (United States)

    Daniele, C. J.; Lorenzo, C. F.

    1980-01-01

    A four working space, double acting piston, Stirling engine simulation is being developed for controls studies. The development method is to construct two simulations, one for detailed fluid behavior, and a second model with simple fluid behaviour but containing the four working space aspects and engine inertias, validate these models separately, then upgrade the four working space model by incorporating the detailed fluid behaviour model for all four working spaces. The single working space (SWS) model contains the detailed fluid dynamics. It has seven control volumes in which continuity, energy, and pressure loss effects are simulated. Comparison of the SWS model with experimental data shows reasonable agreement in net power versus speed characteristics for various mean pressure levels in the working space. The four working space (FWS) model was built to observe the behaviour of the whole engine. The drive dynamics and vehicle inertia effects are simulated. To reduce calculation time, only three volumes are used in each working space and the gas temperature are fixed (no energy equation). Comparison of the FWS model predicted power with experimental data shows reasonable agreement. Since all four working spaces are simulated, the unique capabilities of the model are exercised to look at working fluid supply transients, short circuit transients, and piston ring leakage effects.

  15. Mobile hydraulic power supply. Liquid piston Stirling engine pump

    Energy Technology Data Exchange (ETDEWEB)

    Ven, James D. van de [100 Institute Road, Department of Mechanical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609 (United States)

    2009-11-15

    Conventional mobile hydraulic power supplies involve numerous kinematic connections and are limited by the efficiency, noise, and emissions of internal combustion engines. The Stirling cycle possesses numerous benefits such as the ability to operate from any heat source, quiet operation, and high theoretical efficiency. The Stirling engine has seen limited success due to poor heat transfer in the working chambers, difficulty sealing low-molecular weight gases at high pressure, and non-ideal piston displacement profiles. As a solution to these limitations, a liquid piston Stirling engine pump is proposed. The liquid pistons conform to irregular volumes, allowing increased heat transfer through geometry features on the interior of the working chambers. Creating near-isothermal operation eliminates the costly external heat exchangers and increases the engine efficiency through decreasing the engine dead space. The liquid pistons provide a positive gas seal and thermal transport to the working chambers. Controlling the flow of the liquid pistons with valves enables matching the ideal Stirling cycle and creates a direct hydraulic power supply. Using liquid hydrogen as a fuel source allows cooling the compression side of the engine before expanded the fuel into a gas and combusting it to heat the expansion side of the engine. Cooling the compression side not only increases the engine power, but also significantly increases the potential thermal efficiency of the engine. A high efficiency Stirling engine makes energy regeneration through reversing the Stirling cycle practical. When used for regeneration, the captured energy can be stored in thermal batteries, such as a molten salt. The liquid piston Stirling engine pump requires further research in numerous areas such as understanding the behavior of the liquid pistons, modeling and optimization of a full engine pump, and careful selection of materials for the extreme operating temperatures. Addressing these obtainable

  16. Wear Resistance and Wear Mechanism of a Hot Dip Aluminized Steel in Sliding Wear Test

    Science.gov (United States)

    Xue, Zhiyong; Hao, Xiaoyang; Huang, Yao; Gu, Lingyun; Ren, Yu; Zheng, Ruipeng

    2016-12-01

    Sliding wear experiments were conducted on a hot dip aluminized steel to investigate its wear resistance and wear mechanism. The wear tests were also carried out on a hot dip galvanized steel and the base material (steel Q345) as a comparison. Results show that the wear resistance and hardness of the hot dip aluminized steel are significantly higher than that of the hot dip galvanized steel and the steel Q345 at room temperature. The better wear resistance of the hot dip aluminized steel attributes mainly to the formation of a transition layer containing abundant Fe-Al intermetallic compounds and the transformation of wear-resisting oxides during the friction process. The main phase in the transition layer is Fe2Al5. The thickness of the transition layer is about 90-120 μm. When the wear load increases from 3 N to 19 N, the wear type of the aluminized layer transform from adhesive wear (3 N) into abrasive wear (7 N) and finally into slight wear mixed with oxidation (higher than 11 N).

  17. Planetary Rings

    CERN Document Server

    Tiscareno, Matthew S

    2011-01-01

    Planetary rings are the only nearby astrophysical disks, and the only disks that have been investigated by spacecraft. Although there are significant differences between rings and other disks, chiefly the large planet/ring mass ratio that greatly enhances the flatness of rings (aspect ratios as small as 1e-7), understanding of disks in general can be enhanced by understanding the dynamical processes observed at close-range and in real-time in planetary rings. We review the known ring systems of the four giant planets, as well as the prospects for ring systems yet to be discovered. We then review planetary rings by type. The main rings of Saturn comprise our system's only dense broad disk and host many phenomena of general application to disks including spiral waves, gap formation, self-gravity wakes, viscous overstability and normal modes, impact clouds, and orbital evolution of embedded moons. Dense narrow rings are the primary natural laboratory for understanding shepherding and self-stability. Narrow dusty...

  18. Instantaneous heat flux flowing into piston top-land surface of D.I. diesel engine; DI diesel kikan no piston top land bu eno shunji netsuryusoku

    Energy Technology Data Exchange (ETDEWEB)

    Taguma, M. [Zexel Corp., Tokyo (Japan); Inui, M.; Enomoto, Y.; Hagihara, Y. [Musashi Institute of Technology, Tokyo (Japan); Koyama, T. [Mitsubishi Motors Co., Tokyo (Japan)

    1997-10-01

    The thermal loads of the piston top-land surface in D.I. diesel engine during actual operation is not cleared. The authors fixed thin film thermocouples in the top-land center of a standard piston, and measured the instantaneous heat fluxes in that place. As a result, the authors made clear the thermal loads of the piston top-land surface in a cycle, and confirmed presence of the flame inflow to the piston top-land center. In addition, the authors made clear the thermal loads of the piston top-land surface in EGR operation. 4 refs., 8 figs.

  19. TIRE WEAR MODELING

    Directory of Open Access Journals (Sweden)

    Rosen IVANOV

    2016-09-01

    Full Text Available On the basis of a known relationship, an enhanced model for specific tire wear per kilometer has been developed. It is appropriate for practical use - for evaluation of the influence of different factors. Two types of experiments have been carried out with a testing device - one without sideslip, but with a known longitudinal slip, and the other one with the same longitudinal slip but also with a known sideslip. As a result, the coefficients of the proportion of the developed model have been evaluated. After the model validation, an analytical investigation concerning the influence of tire pressure, sideslip and longitudinal slip on the tire wear has been carried out. The results are presented graphically.

  20. Three-dimensional Casimir piston for massive scalar fields

    Science.gov (United States)

    Lim, S. C.; Teo, L. P.

    2009-08-01

    We consider Casimir force acting on a three-dimensional rectangular piston due to a massive scalar field subject to periodic, Dirichlet and Neumann boundary conditions. Exponential cut-off method is used to derive the Casimir energy. It is shown that the divergent terms do not contribute to the Casimir force acting on the piston, thus render a finite well-defined Casimir force acting on the piston. Explicit expressions for the total Casimir force acting on the piston is derived, which show that the Casimir force is always attractive for all the different boundary conditions considered. As a function of a - the distance from the piston to the opposite wall, it is found that the magnitude of the Casimir force behaves like 1/a4 when a→0+ and decays exponentially when a→∞. Moreover, the magnitude of the Casimir force is always a decreasing function of a. On the other hand, passing from massless to massive, we find that the effect of the mass is insignificant when a is small, but the magnitude of the force is decreased for large a in the massive case.

  1. A CWT-based methodology for piston slap experimental characterization

    Science.gov (United States)

    Buzzoni, M.; Mucchi, E.; Dalpiaz, G.

    2017-03-01

    Noise and vibration control in mechanical systems has become ever more significant for automotive industry where the comfort of the passenger compartment represents a challenging issue for car manufacturers. The reduction of piston slap noise is pivotal for a good design of IC engines. In this scenario, a methodology has been developed for the vibro-acoustic assessment of IC diesel engines by means of design changes in piston to cylinder bore clearance. Vibration signals have been analysed by means of advanced signal processing techniques taking advantage of cyclostationarity theory. The procedure departs from the analysis of the Continuous Wavelet Transform (CWT) in order to identify a representative frequency band of piston slap phenomenon. Such a frequency band has been exploited as the input data in the further signal processing analysis that involves the envelope analysis of the second order cyclostationary component of the signal. The second order harmonic component has been used as the benchmark parameter of piston slap noise. An experimental procedure of vibrational benchmarking is proposed and verified at different operational conditions in real IC engines actually equipped on cars. This study clearly underlines the crucial role of the transducer positioning when differences among real piston-to-cylinder clearances are considered. In particular, the proposed methodology is effective for the sensors placed on the outer cylinder wall in all the tested conditions.

  2. Transtibial prosthetic suspension: Less pistoning versus easy donning and doffing

    Directory of Open Access Journals (Sweden)

    Hossein Gholizadeh, MEngSc

    2012-12-01

    Full Text Available Poor suspension increases slippage of the residual limb inside the socket during ambulation. The main purpose of this article is to evaluate the pistoning at the prosthetic liner-socket interface during gait and assess patients’ satisfaction with two different liners. Two prostheses with seal-in and locking liners were fabricated for each of the 10 subjects with transtibial amputation. The Vicon motion system was used to measure the pistoning during gait. The subjects were also asked to complete a Prosthesis Evaluation Questionnaire. The results revealed higher pistoning inside the socket during gait with the locking liner than with the seal-in liner (p < 0.05. The overall satisfaction with the locking liner was higher (p < 0.05 because of the relative ease with which the patients could don and doff the device. As such, pistoning may not be the main factor that determines patients’ overall satisfaction with the prosthesis and other factors may also contribute to comfort and satisfaction with prostheses. The article also verifies the feasibility of the Vicon motion system for measuring pistoning during gait.

  3. Spherical rotary piston machine as an artificial heart.

    Science.gov (United States)

    Wipf, S L

    1991-01-01

    A positive displacement pump with six rotary pistons was proposed as an artificial heart. The pump's design was characterized by high symmetry and compactness. Thus, a spherical volume of 4 1/4 inch diameter sufficed for a pump delivering 10 L/min at 120 pulses/min with the pistons turning at 30 rpm. The pistons and four connecting gears were the only moving parts. The pump functions in two separate halves as left and right ventricles, with two of the six pistons each having inlet and outlet passages, and one of them replacing mitral and pulmonary valves with the other, tricuspid and aortic valves. The function of the intraventricular septum was provided by the other four pistons whose interiors also accommodated driving motors each capable of 0.4 Nm torque for a combined power of 5 watts. There were no stagnant regions in the pumping volume, and at all internal surfaces in contact with blood, there was periodic shear stress not exceeding approximately 300 Pa.

  4. Magnetic Piston Propagation in a 100-ns Plasma Opening Switch

    Science.gov (United States)

    Weingarten, A.; Grabowski, C.; Chakrabarti, N.; Maron, Y.; Fruchtman, A.

    1998-11-01

    The propagation of a magnetic piston through the plasma of a 90-ns, 170-kA POS is observed by studying the electron density, magnetic field, and ion velocity evolution. For the prefilled plasma n_e=(2.2± 0.5)× 10^14 cm-3, and T_e=5.5± 1 eV. The plasma composition is studied from absolute line intensities and collisional-radiative calculations. Most of the plasma ions are protons (90% near the cathode) with the rest being mainly CIV. The Hall-MHD conditions are not fulfilled for our experiment and ion motion is significant. The 3D-resolved ne evolution during the current pulse is studied from the line intensities of ions doped in the plasma using laser evaporation, and the magnetic field from Zeeman splitting. A diagonal magnetic piston propagates from the generator towards the load at about half the proton Alfven velocity. The protons are specularly reflected by the piston, while the heavy ions cross the potential hill in the piston, acquiring a lower velocity. The proton reflection causes an increase of ne ahead of the piston, followed by a sharp (10-20 ns) and substantial drop in ne (to 10-50% from the initial value). The magnetic field distribution studied using chordal observation, and theoretical analysis of ne and the magnetic field evolution are presented.

  5. Theoretical Analysis of Noise of Piston Knocking Cylinder Wall in Automotive Engines

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Based on the loading conditions of engine, applying difference method to solve the hydrodynamic lubrication equation of piston skirt movement, the force acting on piston skirt and the moment on wrist pin were obtained. A computer program for simulating the piston second order motion was conducted to calculate the lateral motion of the upper part and the bottom part of piston skirts of the engine of automotive model CA1091. From the simulated result, the maximal impacting phase and the maximal impacting region of the piston were obtained. The result can be used for designing engine, diagnosing the noise of piston knocking cylinder wall and explaining many practical fault phenomena in theory.

  6. Transformation of Reciprocating Hydrogen Compressor Guide Ring%往复式氢气压缩机导向环改造

    Institute of Scientific and Technical Information of China (English)

    张钊; 王雁云

    2012-01-01

    Reciprocating hydrogen compressor is generally to select oil lubrication.Coke is inevitably produced when it is woking, meanwhile, medium contains impurities, which all can aggravate the wear of piston guide ring and make it cannot achieve the desired service life.Combining theoretical basis and practical experience, maintenance personnel has adjusted oil injection and increased the thickness of guide ring,which can make it achieve the desired service life.It has a certain reference for similar type compressors.%往复式氢气压缩机一般选择油润滑,在工作时不可避免产生积炭;同时介质中也含有杂质,都会加剧活塞导向环的磨损,使其无法达到应有的使用寿命.维修人员调整了注油量,增加了导向环的厚度,使其达到使用寿命,对于此类压缩机有一定的借鉴意义.

  7. Engine oil wear resistance

    Directory of Open Access Journals (Sweden)

    A.N. Farhanah

    2015-03-01

    Full Text Available Lubricants play a vital role in an internal combustion engine to lubricate parts and help to protect and prolong the engine life. Lubricant also will help to reduce wear by creating lubricating film between the moving parts hence reduce metal-to-metal contacts. Engine oil from three different manufacturers with the same SAE viscosity grade available in market does not mean it will have the same lubricity for an engine. In this study, commercial mineral lubrication oil (SAE 10W-30 from three manufacturers was investigated to compare the lubrication performance at three different temperatures (40˚C, 70˚C and 100˚C in 60 minutes time duration by using four ball wear tester. The speed will be varied from 1000 rpm to 2500 rpm. Results show that all three lubricants have different lubricity performance; the smaller the wear scar, the better the lubricant since the lubricant can protect the moving surfaces from direct metal-to-metal contact occur.

  8. RE-1000 free-piston Stirling engine update

    Science.gov (United States)

    Schreiber, J.

    1985-01-01

    A free piston Stirling engine was tested. The tests performed over the past several years on the single cylinder engine were designed to investigate the dynamics of a free piston Stirling engine. The data are intended to be used primarily for computer code validation. The tests designed to investigate the sensitivity of the engine performance to variations in working space pressure, heater and cooler temperatures, regenerator porosity, power piston mass and displacer dynamics were completed. In addition, some data were recorded with alternate working fluids. A novel resonant balance system for the engine was also tested. Some preliminary test results of the tests performed are presented along with an outline of future tests to be run with the engine coupled to a hydraulic output unit. A description of the hydraulic output unit is given.

  9. P-REx: the piston drift reconstruction experiment

    Science.gov (United States)

    Pott, Jörg-Uwe; Fu, Qiang; Widmann, Felix; Peter, Diethard

    2016-08-01

    For sensitive infra-red long-baseline interferometry, it is crucial to control the differential piston between the apertures. Classically this is achieved with a fringe tracker which measures the movement of the interferometric fringes. In this paper, we describe a new method to reconstruct the piston variation introduced by atmospheric turbulence with real-time data from adaptive optics wave-front sensing. Concurrently, the dominant wind speed vector can also be retrieved. The method is analyzed in simulation for atmospheric turbulence of various strength, and wind vectors varying with layer altitude. The results from the simulations show that this method could help to reliably retrieve the piston variation and wind speed from wavefront sensor data. The method is related to concepts of predictive control AO algorithms and reconstruction of the point spread function.

  10. RE-1000 free-piston Stirling engine update

    Science.gov (United States)

    Schreiber, J.

    1985-01-01

    A free piston Stirling engine was tested. The tests performed over the past several years on the single cylinder engine were designed to investigate the dynamics of a free piston Stirling engine. The data are intended to be used primarily for computer code validation. The tests designed to investigate the sensitivity of the engine performance to variations in working space pressure, heater and cooler temperatures, regenerator porosity, power piston mass and displacer dynamics were completed. In addition, some data were recorded with alternate working fluids. A novel resonant balance system for the engine was also tested. Some preliminary test results of the tests performed are presented along with an outline of future tests to be run with the engine coupled to a hydraulic output unit. A description of the hydraulic output unit is given.

  11. Pure mechanical wear loss measurement in corrosive wear

    Indian Academy of Sciences (India)

    Yanliang Huang; Xiaoxia Jiang; Sizuo Li

    2000-12-01

    The method for the measurement of the pure mechanical wear loss for 321 stainless steel, 1045 steel and pure iron in the study of the synergy between corrosion and wear was studied. The methods studied included the measurement in distilled water, by cathodic protection and by adding inhibitor KI, and all were compared with the wear loss in air. The experiment showed that the pure mechanical wear losses and friction coefficients obtained by the three methods were close to each other and can be used to calculate the various wear components in the study of the interaction of corrosion and wear, but the measurements in distilled water for pure iron and 1045 steel are not recommended due to their corrosion.

  12. High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A.; Chen, Po Shou

    2003-01-01

    Originally developed by NASA as high performance piston alloys to meet U.S. automotive legislation requiring low exhaust emission, the novel NASA alloys now offer dramatic increase in tensile strength for many other applications at elevated temperatures from 450 F (232 C) to about 750 F (400 C). It is an ideal low cost material for cast automotive components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. It can be very economically produced from conventional permanent mold, sand casting or investment casting, with silicon content ranging from 6% to 18%. At high silicon levels, the alloy exhibits excellent thermal growth stability, surface hardness and wear resistant properties.

  13. Assembly for electrical conductivity measurements in the piston cylinder device

    Science.gov (United States)

    Watson, Heather Christine [Dublin, CA; Roberts, Jeffrey James [Livermore, CA

    2012-06-05

    An assembly apparatus for measurement of electrical conductivity or other properties of a sample in a piston cylinder device wherein pressure and heat are applied to the sample by the piston cylinder device. The assembly apparatus includes a body, a first electrode in the body, the first electrode operatively connected to the sample, a first electrical conductor connected to the first electrode, a washer constructed of a hard conducting material, the washer surrounding the first electrical conductor in the body, a second electrode in the body, the second electrode operatively connected to the sample, and a second electrical conductor connected to the second electrode.

  14. Experimental Study on the WavePiston Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Angelelli, E.

    This report presents the results of an experimental study of the power performance of the WavePiston wave energy converter. It focuses mainly on evaluating the power generating capabilities of the device and the effect of the following issues: Scaling ratios PTO loading Wave height and wave period...... dependency Oblique incoming waves Distance between plates During the study, the model supplied by the client, WavePiston, has been rigorously tested as all the anticipated tests have been done thoroughly and during all tests, good quality data has been obtained from all the sensors....

  15. A mechanical model of an axial piston machine

    OpenAIRE

    Löfstrand Grip, Rasmus

    2009-01-01

    A mechanical model of an axial piston-type machine with a so-called wobble plate and Z-shaft mechanism is presented. The overall aim is to design and construct an oil-free piston expander demonstrator as a first step to realizing an advanced and compact small-scale steam engine system. The benefits of a small steam engine are negligible NOx emissions (due to continuous, low-temperature combustion), no gearbox needed, fuel flexibility (e.g., can run on biofuel and solar), high part-load effici...

  16. Planetary Rings

    Science.gov (United States)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  17. CAD/CAM/CAI Application for High-Precision Machining of Internal Combustion Engine Pistons

    Directory of Open Access Journals (Sweden)

    V. V. Postnov

    2014-07-01

    Full Text Available CAD/CAM/CAI application solutions for internal combustion engine pistons machining was analyzed. Low-volume technology of internal combustion engine pistons production was proposed. Fixture for CNC turning center was designed.

  18. Simulation of a Martini Displacer Free Piston Stirling Engine for Electric Power Generation

    National Research Council Canada - National Science Library

    Pascal Stouffs; Nasser Seraj Mehdizadeh

    2000-01-01

    .... A dynamic simulation of this engine has been developed using a decoupled analysis. The equation of motion of the free piston induces a strong coupling between the electrical load and the thermodynamics inside the free piston Stirling engine...

  19. The influence oil film lubrication of the piston-cylinder dynamic

    Directory of Open Access Journals (Sweden)

    Adriana Tokar

    2008-10-01

    Full Text Available An analytical study of the dynamics of a piston in a reciprocating engine was conducted. The equation of Reynolds and moving of piston are derived. The analysis, which incorporates a hydrodynamic lubrication model, was applied to M501 diesel engine. The results of this study indicate that piston dynamics were found to be sensitive to piston-cylinder bore clearance, location of the wrist pin and lubricant viscosity, underscoring their importance in engine design.

  20. 往复活塞压缩机的偏心活塞%Off-centre Piston in Reciprocator Piston Compressor

    Institute of Scientific and Technical Information of China (English)

    许大钊

    2011-01-01

    This article has given kinematical analytics and dynamical analytics for the off-centre piston in the crank link mechanism.According to the results of the theoretic analytics, the features and applications of the offcentre piston have been pointed out.%对偏心活塞的曲柄连杆机构进行运动分析和动力分析.根据理论分析的结果,提出了偏心活塞曲柄连杆机构的特点及其应用.

  1. Friction and wear calculation methods

    CERN Document Server

    Kragelsky, I V; Kombalov, V S

    1981-01-01

    Friction and Wear: Calculation Methods provides an introduction to the main theories of a new branch of mechanics known as """"contact interaction of solids in relative motion."""" This branch is closely bound up with other sciences, especially physics and chemistry. The book analyzes the nature of friction and wear, and some theoretical relationships that link the characteristics of the processes and the properties of the contacting bodies essential for practical application of the theories in calculating friction forces and wear values. The effect of the environment on friction and wear is a

  2. Wear of polymers and composites

    CERN Document Server

    Abdelbary, Ahmed

    2015-01-01

    In the field of tribology, the wear behaviour of polymers and composite materials is considered a highly non-linear phenomenon. Wear of Polymers and Composites introduces fundamentals of polymers and composites tribology. The book suggests a new approach to explore the effect of applied load and surface defects on the fatigue wear behaviour of polymers, using a new tribometer and thorough experiments. It discusses effects of surface cracks, under different static and cyclic loading parameters on wear, and presents an intelligent algorithm, in the form of a neural network, to map the relations

  3. Transitions in Wear and Friction of Carbon Fiber Reinforced Copper Matrix Composite Sliding Against AISI-1045 Steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The friction and wear properties of carbon fiber reinforced copper matrix composite in dry sliding against AISI-1045 steel was evaluated by a block-on-ring test machine. It was shown that the low frictional factor and wear rate of the composite block could be maintained when pressure or velocity was below a certain value. But when the pressure or velocity exceeded the critical value, the friction factor and wear rate tended to increase rapidly with pressure and sliding velocity. The morphologies, elemental compositions, and surface profile of worn composite surfaces at different wear stages were analyzed by means of scanning electron microscopy, energy dispersive spectrometry, and profile-meter. It was found that low values of friction and wear were due to a thin solid film forming on the surface of the composite block which includes carbon and copper at a mild wear stage. The film could impede adhesion and provide some degree of self-lubrication. When the film included more metal elements and were damaged, severe wear happened, and the wear rate increased sharply. As a result, a transition diagram in friction and wear was constructed, which provided pressure and velocity conditions of change from mild wear and low friction to severe wear and high friction for the wear-resisting design.

  4. Investigation of Valve Plate in Water Hydraulic Axial Piston Motor%水压轴向柱塞马达配流盘的研究

    Institute of Scientific and Technical Information of China (English)

    聂松林; 李壮云; 杨曙东

    2002-01-01

    This paper has introduced the developments of water hydraulic axial piston equipments. According to the effects of physicochemical properties of water on water hydraulic components, a novel valve plate for water hydraulic axial motor has been put forward, whose moment exerted by the fluid field between valve plate and bearing plate is balanced entirely. The material screening experiment of valve plate is done on the test rig. Through numerical simulation the effects of some geometry parameters on the performance of water hydraulic motor have been studied. The silencing grooves on the valve plate in water hydraulic motor can reduce the pressure shock and the occurrence of cavitation effectively. It is evident that the appropriate structure should change the wear status between matching pairs and reduces the wear and specific pressure of the matching pairs. The specimen with the new type valve plate is used in a tool system.

  5. STUDY ON RECIPROCATING SEALS FOR A LARGER DIAMETER AXIAL PISTON

    Institute of Scientific and Technical Information of China (English)

    Yang Jian; Yang Huayong; Xu Bing

    2004-01-01

    Sealing performance of the reciprocating seals on a larger diameter (100 mm in diameter ) axial piston is theoretically investigated.Based on the characteristics of the clearance flow between the seal and the piston, reasonable boundary conditions for Navier-Stokes equations are determined and the equations are modified, so that the final equations can describe the real flow state of the clearance flow.Through combining the final equations with finite element method, the pressure distributions within the clearance field during the reciprocating motion of the piston and the leakage rate with the pressure are studied.The deflections of the seal which affect sealing performance are calculated as well.Sealing performance of piston seals using oil as the working liquid is compared with using water.It is concluded that the seal using water as the working liquid is under dry friction, which cannot be dealt with the theory of fluid mechanics.The seal structure is only acceptable using oil as the working liquid..

  6. Experiments on the WavePiston, Wave Energy Converter

    DEFF Research Database (Denmark)

    Angelelli, E.; Zanuttigh, B.; Kofoed, Jens Peter

    2011-01-01

    This paper analyses the performance of a new Wave Energy Converter (WEC) of the Oscillating Water Column type (OWC), named WavePiston. This near-shore floating device is composed of plates (i.e. energy collectors) sliding around a cylinder, that is placed perpendicular to the shore. Tests...

  7. Spatial impulse responses from a flexible baffled circular piston

    NARCIS (Netherlands)

    Aarts, R.M.; Janssen, A.J.E.M.

    2011-01-01

    The theory of orthogonal polynomial (Zernike) expansions of functions on a disk, as used in the diffraction theory of optical aberrations, is applied to obtain (semi-) analytical expressions for the spatial impulse responses arising from a non-uniformly moving, baffled, circular piston. These expres

  8. Closing the innovation cycle in lightweighting compressor pistons technolog

    NARCIS (Netherlands)

    Wentzel, C.; Eijk, A.; Groenewegen, G.; Bergsma, O.

    2016-01-01

    What started out as an exercise in exploring the weight reduction potential of those allegedly “heavy recip crossheads”, turned out to be a fast leap towards implementation of a new hybrid material concept for very lightweight pistons. This was enabled by a next phase in the EFRC R&D group research

  9. Development and Testing of a Novel Green Propellant Piston Tank

    Science.gov (United States)

    Diaz, C. E.; Cavender, D. P.; Higdon, K.; Abrams, J.; Duchek, M. E.; Mader, H.

    2017-01-01

    Analytical Mechanics Associates (AMA), in cooperation with NASA Marshall Space Flight Center's (MSFC's) Spacecraft Propulsion Systems Branch, developed and tested a novel propellant tank design that employs an internal piston pressurized with an inert gas to expel propellant to thrusters. During the course of this activity, AMA designed, oversaw fabrication, and delivered to MSFC for testing, a piston propellant tank sized for 3U or larger CubeSats. MSFC conducted liquid expulsion testing using ethylene glycol as a referee fluid to map the tank's performance at different pressures and piston positions. Following the expulsion test campaign, the tank is planned to be integrated into a propulsion system test bed for hot fire tests with a 100mN monopropellant thruster to evaluate the tank's influence on thruster performance when operated in a flight like manner. Described in this paper is a comprehensive summary of how the tanks were designed, built, and tested. The fundamental knowledge gained through the fabrication and testing of these tanks gives evidence that the piston tank design may be scalable to meet the requirements and constraints of other small satellites.

  10. SUPRAMITRAL RING

    Directory of Open Access Journals (Sweden)

    Rajesh G

    2011-11-01

    Full Text Available Supra mitral ring is a rare cause for congenital mitral valve obstr uction. The reported incidence of supramitral ring is 0.2-0.4% in general population and 8% in patients with congenital mitral valve disease. The condition is characterized by an abnormal ridge of connective tissue often circumferential in shape ,on the atrial side of the mitral valve encroaching on the orifice of the mitral valve. It may adhere to the leaflets of the valve and restrict their movements. Although a supramitral ring may be rarely nonobstructive, it often results in mitral valve inflow obstruction.

  11. Determinantal rings

    CERN Document Server

    Bruns, Winfried

    1988-01-01

    Determinantal rings and varieties have been a central topic of commutative algebra and algebraic geometry. Their study has attracted many prominent researchers and has motivated the creation of theories which may now be considered part of general commutative ring theory. The book gives a first coherent treatment of the structure of determinantal rings. The main approach is via the theory of algebras with straightening law. This approach suggest (and is simplified by) the simultaneous treatment of the Schubert subvarieties of Grassmannian. Other methods have not been neglected, however. Principal radical systems are discussed in detail, and one section is devoted to each of invariant and representation theory. While the book is primarily a research monograph, it serves also as a reference source and the reader requires only the basics of commutative algebra together with some supplementary material found in the appendix. The text may be useful for seminars following a course in commutative ring theory since a ...

  12. Fabrication, microstructural characterization and wear characteristics of A380 alloy-alumina composites

    KAUST Repository

    Nurani, Sheikh Jaber

    2016-03-10

    To obtain better mechanical and tribological properties than aluminium alloys aluminium is reinforced with alumina particles making aluminium metal matrix composites. In this work scrap piston A380 alloy was used as the matrix alloy. Alumina particles were added by 5%, 10% and 15% into matrix alloy respectively to form desired composites by stir casting technique. Pin on disc wear testing machine with counter surface as steel disc of hardness HRC 32 and surface roughness of 0.62 μm was used to conduct the wear test. In result composites showed superior wear resistance property over A380 alloy. The effect of load, sliding speed and sliding distance on wear behaviour were also examined in this study. Wear mechanism was identified from the worn surface. Both optical and scanning electron microscope (SEM) of the composites was performed to determine the microstructures. Optical micrograph shows grain size decreases with addition of alumina particles. EDS analysis was performed to confirm the presence of α-Al matrix, primary Si particles and intermetallic. As a general method, phase compositions were analyzed by using a scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy (EDS). Optical microstructures were consistent with the SEM micrographs. © 2015 IEEE.

  13. Cave Rings

    Science.gov (United States)

    2010-10-13

    hypothesis, that cave rings are formed in the same manner as coffee rings[3], that is, due to the enhanced deposition at the edges of sessile drops ...ring’ is the deposit formed when a sessile drop of a solution containing dissolved particles, such as coffee or salt, dries. This was investigated by...who expanded on Deegan et al.[3] to find an exact form for the evaporation flux over a sessile drop . It turns out that solving 179 for the flux is

  14. Detailed study of oxidation/wear mechanism in lox turbopump bearings

    Science.gov (United States)

    Chase, T. J.; McCarty, J. P.

    1993-12-01

    Wear of 440C angular contact ball bearings of the phase 2 high pressure oxygen turbopump (HPOTP) of the space shuttle main engine (SSME) has been studied by means of various advanced nondestructive techniques (NDT) and modeled with reference to all known material, design, and operation variables. Three modes dominating the wear scenario were found to be the adhesive/sheer peeling (ASP), oxidation, and abrasion. Bearing wear was modeled in terms of the three modes. Lacking a comprehensive theory of rolling contact wear to date, each mode is modeled after well-established theories of sliding wear, while sliding velocity and distance are related to microsliding in ball-to-ring contacts. Microsliding, stress, temperature, and other contact variables are evaluated with analytical software packages of SHABERTH(TM)/SINDA(TM) and ADORE(TM). Empirical constants for the models are derived from NIST experiments by applying the models to the NIST wear data. The bearing wear model so established precisely predicts quite well the average ball wear rate for the HPOTP bearings. The wear rate has been statistically determined for the entire population of flight and development bearings based on Rocketdyne records to date. Numerous illustrations are given.

  15. Wear of micro end mills

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2005-01-01

    This paper addresses the important issue of wear on micro end mills considering relevant metrological tools for its characterization and quantification. Investigation of wear on micro end mills is particularly difficult and no data are available in the literature. Small worn volumes cause large d...

  16. Vascular rings.

    Science.gov (United States)

    Backer, Carl L; Mongé, Michael C; Popescu, Andrada R; Eltayeb, Osama M; Rastatter, Jeffrey C; Rigsby, Cynthia K

    2016-06-01

    The term vascular ring refers to congenital vascular anomalies of the aortic arch system that compress the esophagus and trachea, causing symptoms related to those two structures. The most common vascular rings are double aortic arch and right aortic arch with left ligamentum. Pulmonary artery sling is rare and these patients need to be carefully evaluated for frequently associated tracheal stenosis. Another cause of tracheal compression occurring only in infants is the innominate artery compression syndrome. In the current era, the diagnosis of a vascular ring is best established by CT imaging that can accurately delineate the anatomy of the vascular ring and associated tracheal pathology. For patients with a right aortic arch there recently has been an increased recognition of a structure called a Kommerell diverticulum which may require resection and transfer of the left subclavian artery to the left carotid artery. A very rare vascular ring is the circumflex aorta that is now treated with the aortic uncrossing operation. Patients with vascular rings should all have an echocardiogram because of the incidence of associated congenital heart disease. We also recommend bronchoscopy to assess for additional tracheal pathology and provide an assessment of the degree of tracheomalacia and bronchomalacia. The outcomes of surgical intervention are excellent and most patients have complete resolution of symptoms over a period of time. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. [Infants wearing teething necklaces].

    Science.gov (United States)

    Taillefer, A; Casasoprana, A; Cascarigny, F; Claudet, I

    2012-10-01

    Numerous infants wear teething necklaces, a quack remedy with a real risk of strangulation or aspiration of small beads. Evaluate parental perceptions and beliefs about the use of teething necklaces and analyze parental knowledge about the associated dangers. Between March and July 2011, in three different pediatric units of a tertiary children's hospital and a general hospital in Toulouse and Montauban (southwest France), voluntary parents were invited to be interviewed about their child wearing a teething necklace. The interviews were conducted following an anthropological approach: they were recorded and then fully transcribed and analyzed. Parents were informed that the conversation was recorded. During the study period, 48 children were eligible. Eleven families refused to participate, 29 parents were interviewed face to face. The children's mean age was 14 years ± 7 months, the male:female ratio was equal to 0.8 (12 boys, 15 girls). The mean age of children when necklace wearing was started was equal to 4 ± 2 months. The mean mother's age was 31 ± 5 years and 33 ± 4 years for fathers. The parents' religion was mostly Catholic (60%). Teething necklaces were mainly made of amber (n=23). Sales information about the risks associated with the necklaces was for the most part absent (92%). The most frequent positive parental perceptions were analgesic properties and a soothing remedy (73%); a birth accessory and memory (64%); an esthetic accessory (60%); a protective amulet (60%); and an alternative or additional element to other traditional therapeutics (55%). The negative parental perceptions (n=4) were an unnecessary accessory, costume jewelry, a pure commercial abuse of a popular belief, a dangerous item with a risk of strangulation, and the absence of proof of its efficacy. Although parents concede that teeth eruption is benign, they fear its related symptoms. To a natural phenomenon a natural response: they use a necklace to satisfy the analogy. The

  18. Switch wear leveling

    Science.gov (United States)

    Wu, Hunter; Sealy, Kylee; Gilchrist, Aaron

    2015-09-01

    An apparatus for switch wear leveling includes a switching module that controls switching for two or more pairs of switches in a switching power converter. The switching module controls switches based on a duty cycle control technique and closes and opens each switch in a switching sequence. The pairs of switches connect to a positive and negative terminal of a DC voltage source. For a first switching sequence a first switch of a pair of switches has a higher switching power loss than a second switch of the pair of switches. The apparatus includes a switch rotation module that changes the switching sequence of the two or more pairs of switches from the first switching sequence to a second switching sequence. The second switch of a pair of switches has a higher switching power loss than the first switch of the pair of switches during the second switching sequence.

  19. Low friction wear resistant graphene films

    Science.gov (United States)

    Sumant, Anirudha V.; Berman, Diana; Erdemir, Ali

    2017-02-07

    A low friction wear surface with a coefficient of friction in the superlubric regime including graphene and nanoparticles on the wear surface is provided, and methods of producing the low friction wear surface are also provided. A long lifetime wear resistant surface including graphene exposed to hydrogen is provided, including methods of increasing the lifetime of graphene containing wear surfaces by providing hydrogen to the wear surface.

  20. Simulation of Thermal-Mechanical Strength for Marine Engine Piston Using FEA

    Directory of Open Access Journals (Sweden)

    Jiang Guo He

    2014-03-01

    Full Text Available Simulation of Thermal-Mechanical Strength for Marine Engine Piston Using FEA Abstract: This paper involves simulation of a 2-stroke 6S35ME marine diesel engine piston to determine its temperature field, thermal, mechanical and coupled thermal-mechanical stress. The distribution and magnitudes of the afore-mentioned strength parameters are useful in design, failure analysis and optimization of the engine piston. The piston model was developed in solid-works and imported into ANSYS for preprocessing, loading and post processing. Material model chosen was 10-node tetrahedral thermal solid 87. The simulation parameters used in this paper were piston material, combustion pressure, inertial effects and temperature. The highest calculated stress was the thermal-mechanical coupled stress and was below the yield stress of the piston material (580Mpa at elevated temperatures hence the piston would withstand the induced stresses during work cycles.

  1. NUMERICAL ANALYSIS OF STRIKE OF PISTON TO CYLINDER UNDER SUPERCHARGE CONDITIONS

    Institute of Scientific and Technical Information of China (English)

    余志壮; 宋正华; 董光能; 谢友柏

    2004-01-01

    Objective To investigate the changes to the strike extent of piston to cylinder after engine supercharge design. Methods The lubrication model between the skirt of piston and liner is established by means of piston dynamics, combined with the hydrodynamic lubrication equation. Optimized numerical analysis method is employed in solving the dynamics and lubrication equations. The analyses about piston strike under two combustion gas pressures are performed. Results The peak values of maximum eccentricity under supercharge condition are much greater than under non-supercharge condition, which means a stronger impulsion of piston to cylinder wall and a greater possibility of scuffing. The horizontal velocities of piston in supercharge condition are larger, which illuminate the more unstable motion state. Conclusion The analysis gives a new conclusion. Combustion gas pressure plays an important role in the piston strike motion. Influences of supercharge should be taken into account so that the traditional product test items can be improved.

  2. A comparative study of Cr-X-N (X=Zr, Si) coatings for the improvement of the low-speed torque efficiency of a hydraulic piston pump

    Science.gov (United States)

    Hong, Yeh-Sun; Lee, Sang-Yul

    2008-02-01

    The internal parts of hydraulic pumps operating at variable speed should be protected from insufficient lubrication. The axial piston type pumps employ a steel-base cylinder barrel rotating on a soft bronze valves plate with a slide contact, where the insufficient lubrication of these components can cause rapid wear of the valve plate and increase the friction loss. In this study, the cylinder barrel surface was deposited with CrZrN coatings, which were expected to improve the tribological contact with a valve plate under low-speed mixed lubrication conditions. Its effect on the improvement of the low-speed torque efficiency of a hydraulic piston pump was investigated and compared with that from the CrSiN coating. The coated cylinder barrels showed much lower friction coefficients and wear rates of the valve plates than the uncoated plasma-nitride one. In particular, the CrZrN coatings revealed better performance than the CrSiN coatings. By representing the improvement in the torque efficiency of the whole pump based upon the degree of the friction coefficient reduction, the CrZrN coatings exhibited approximately a 0.35% higher improvement at 300 bar and 100 rpm than CrSiN coatings. The possible failure modes of the coatings coated on the barrel were sugested and the microstructures of the coatings seemed to have a strong effect on the film failure mode.

  3. Tribological performance evaluation of tungsten carbide-based cermets and development of a fracture mechanics wear model

    Energy Technology Data Exchange (ETDEWEB)

    Bhagat, R.B. [Pennsylvania State Univ., State College, PA (United States). Applied Research Lab.; Conway, J.C. Jr. [Pennsylvania State Univ., State College, PA (United States). Applied Research Lab.; Amateau, M.F. [Pennsylvania State Univ., State College, PA (United States). Applied Research Lab.; Brezler, R.A. III [Pennsylvania State Univ., State College, PA (United States). Applied Research Lab.

    1996-12-15

    Tungsten carbide tools may exhibit sudden brittle fracture at high stresses such as are encountered in shear and slitter knives. This has limited the use of tungsten carbide tools to certain applications in spite of their high hardness and wear resistance. The objective of this investigation is to evaluate the tribological performance of selected cermets and develop a fracture mechanics wear model. Six compositions of WC-Co materials (Co ranging from 4 to 30% by weight) with or without TiC, NbC, TaC, or Mo{sub 2}C were selected for relating wear modes of these tool materials to pertinent mechanical properties such as fracture toughness and hardness. The influence of mechanical properties such as Young`s modulus, hardness, fracture toughness, modulus of rupture, and Weibull modulus on wear rates and wear modes of the selected materials is presented and discussed. The major mechanisms of wear in WC-Co materials are discussed as they apply to the development of suitable relationships between wear and mechanical properties. The wear process is by the transfer of steel from the ring to the cemented carbide block specimens, initiation of mode I cracks normal to the mating surface, propagation of mode II cracks parallel to the wear surfaces and the subsequent separation of platelets with adhered WC and Co particles through adhesive forces with the steel ring. The wear rates of the cermets do not show a consistent relationship with mode I or mode II fracture toughness, but a general trend of decreasing wear rate with hardness is seen. This suggests that the tribological performance of these cermets depends on certain specific functions of pertinent parameters including fracture toughness, hardness, applied load, coefficient of friction and microstructural characteristics. A fracture mechanics-based wear model has been developed to relate the steady state wear rate (W{sub ss}) to hardness, mode II fracture toughness, coefficient of friction, and applied load. (orig./MM)

  4. High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    In this paper, a new high strength and wear resistant aluminum cast alloy invented by NASA-MSFC for high temperature applications will be presented. Developed to meet U.S. automotive legislation requiring low-exhaust emission, the novel NASA 398 aluminum-silicon alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (500 F-800 F), enabling new pistons to utilize less material, which can lead to reducing part weight and cost as well as improving performance. NASA 398 alloy also offers greater wear resistance, surface hardness, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys for several commercial and automotive applications. The new alloy can be produced economically using permanent steel molds from conventional gravity casting or sand casting. The technology was developed to stimulate the development of commercial aluminum casting products from NASA-developed technology by offering companies the opportunity to license this technology.

  5. Tool wear mechanism in turning of novel wear-resisting aluminum bronze

    Institute of Scientific and Technical Information of China (English)

    倪东惠; 夏伟; 张大童; 郭国文; 邵明

    2003-01-01

    Tool wear and wear mechanism during the turning of a wear-resisting aluminum bronze have been stud-ied. Tool wear samples were prepared by using M2 high-speed steel and YW1 cemented carbide tools to turn a novelhigh strength, wear resisting aluminum bronze without coolant and lubricant. Adhesion of workpiece materials wasfound on tool's surface. Under the turning condition used in this study major wear mechanisms for turning aluminumbronze using M2 high-speed steel tool are diffusion wear, adhesive wear and plastic deformation and shear on thecrater. Partial melting of high-speed steel on the rake plays a role in the tool wear also. Major wear mechanisms forturning aluminum bronze using YW1 cemented carbide tool are diffusion wear, attrition wear and sliding wear. Tocontrol the machining temperature is essential to reduce tool wear.

  6. Topological rings

    CERN Document Server

    Warner, S

    1993-01-01

    This text brings the reader to the frontiers of current research in topological rings. The exercises illustrate many results and theorems while a comprehensive bibliography is also included. The book is aimed at those readers acquainted with some very basic point-set topology and algebra, as normally presented in semester courses at the beginning graduate level or even at the advanced undergraduate level. Familiarity with Hausdorff, metric, compact and locally compact spaces and basic properties of continuous functions, also with groups, rings, fields, vector spaces and modules, and with Zorn''s Lemma, is also expected.

  7. Externally heated valve engine a new approach to piston engines

    CERN Document Server

    Kazimierski, Zbyszko

    2016-01-01

    This book reports on a novel approach for generating mechanical energy from different, external heat sources using the body of a typical piston engine with valves. By presenting simple yet effective numerical models, the authors show how this new approach, which combines existing internal combustion technology with a lubrication system, is able to offer an economic solution to the problem of mechanical energy generation in piston engines. Their results also show that a stable heat generation process can be guaranteed outside of the engine. The book offers a detailed report on physical and numerical models of 4-stroke and 2-stroke versions of the EHVE together with different models of heat exchange, valves and results of their simulations. It also delivers the test results of an engine prototype run in laboratory conditions. By presenting a novel theoretical framework and providing readers with extensive knowledge of both the advantages and challenges of the method, this book is expected to inspire academic re...

  8. Palm Power Free-Piston Stirling Engine Control Electronics

    Science.gov (United States)

    Keiter, Douglas E.; Holliday, Ezekiel

    2007-01-01

    A prototype 35We, JP-8 fueled, soldier-wearable power system for the DARPA Palm Power program has been developed and tested by Sunpower. A hermetically-sealed 42We Sunpower Free-Piston Stirling Engine (FPSE) with integral linear alternator is the prime mover for this system. To maximize system efficiency over a broad range of output power, a non-dissipative, highly efficient electronic control system which modulates engine output power by varying piston stroke and converts the AC output voltage of the FPSE into 28Vdc for the Palm Power end user, has been designed and demonstrated as an integral component of the Palm Power system. This paper reviews the current status and progress made in developing the control electronics for the Palm Power system, in addition to describing the operation and demonstrated performance of the engine controller in the context of the current JP-8 fueled Palm Power system.

  9. Microstructure and Sliding Wear Performance of Cr7C3-(Ni,Cr)3(Al,Cr) Coating Deposited from Cr7C3 In Situ Formed Atomized Powder

    Science.gov (United States)

    Zhu, Hong-Bin; Shen, Jie; Gao, Feng; Yu, Yueguang; Li, Changhai

    2017-01-01

    This work is aimed at developing a new type of Cr7C3-(Ni,Cr)3(Al,Cr) coating for parts used in heavy-duty diesel engines. The feedstock, in which the stripe-shaped Cr7C3 was in situ formed, was firstly prepared by vacuum melting and gas atomization and then subjected by high-velocity oxy-fuel spraying to form the coatings. The carbon content, microstructure and phase constitution of the powders, as well as the sprayed coatings, were analyzed by chemical analysis, SEM and XRD. The hardness and sliding wear performance of the sprayed coatings were also tested and compared to a commercial Cr3C2-NiCr coating used on piston rings. The results showed that the content of carbon in feedstock was almost the same as designed, and that the volume content of in situ formed Cr7C3 was increased with carbon and chromium added. The major phases of the powders and sprayed coatings are Cr7C3 and Cr-alloyed Ni3Al. Only a small amount of carbon lost during the spraying process. As Cr7C3 content increased in the coatings, the microhardness at room temperature was firstly increased to about 1000Hv0.3. The microhardness of the coatings stayed almost constant, while the testing temperature was raised up to 700 °C for 0.5 h, which illustrates the potential application of the investigated coatings under high temperature conditions. The coatings containing 70 and 77 vol.% Cr7C3 showed the most promising wear resistance, lower friction coefficient and better tribological compatibility to gray cast iron counterpart than other tested Cr7C3-(Ni,Cr)3(Al,Cr) coatings and the reference Cr3C2-NiCr coating.

  10. Microstructure and Sliding Wear Performance of Cr7C3-(Ni,Cr)3(Al,Cr) Coating Deposited from Cr7C3 In Situ Formed Atomized Powder

    Science.gov (United States)

    Zhu, Hong-Bin; Shen, Jie; Gao, Feng; Yu, Yueguang; Li, Changhai

    2016-12-01

    This work is aimed at developing a new type of Cr7C3-(Ni,Cr)3(Al,Cr) coating for parts used in heavy-duty diesel engines. The feedstock, in which the stripe-shaped Cr7C3 was in situ formed, was firstly prepared by vacuum melting and gas atomization and then subjected by high-velocity oxy-fuel spraying to form the coatings. The carbon content, microstructure and phase constitution of the powders, as well as the sprayed coatings, were analyzed by chemical analysis, SEM and XRD. The hardness and sliding wear performance of the sprayed coatings were also tested and compared to a commercial Cr3C2-NiCr coating used on piston rings. The results showed that the content of carbon in feedstock was almost the same as designed, and that the volume content of in situ formed Cr7C3 was increased with carbon and chromium added. The major phases of the powders and sprayed coatings are Cr7C3 and Cr-alloyed Ni3Al. Only a small amount of carbon lost during the spraying process. As Cr7C3 content increased in the coatings, the microhardness at room temperature was firstly increased to about 1000Hv0.3. The microhardness of the coatings stayed almost constant, while the testing temperature was raised up to 700 °C for 0.5 h, which illustrates the potential application of the investigated coatings under high temperature conditions. The coatings containing 70 and 77 vol.% Cr7C3 showed the most promising wear resistance, lower friction coefficient and better tribological compatibility to gray cast iron counterpart than other tested Cr7C3-(Ni,Cr)3(Al,Cr) coatings and the reference Cr3C2-NiCr coating.

  11. An Approximate Solution for Spherical and Cylindrical Piston Problem

    Indian Academy of Sciences (India)

    S K Singh; V P Singh

    2000-02-01

    A new theory of shock dynamics (NTSD) has been derived in the form of a finite number of compatibility conditions along shock rays. It has been used to study the growth and decay of shock strengths for spherical and cylindrical pistons starting from a non-zero velocity. Further a weak shock theory has been derived using a simple perturbation method which admits an exact solution and also agrees with the classical decay laws for weak spherical and cylindrical shocks.

  12. Free piston variable-stroke linear-alternator generator

    Science.gov (United States)

    Haaland, Carsten M.

    1998-01-01

    A free-piston variable stroke linear-alternator AC power generator for a combustion engine. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod.

  13. Aluminium matrix heterophase composites for air compressor pistons

    Directory of Open Access Journals (Sweden)

    M.Dyzia

    2011-04-01

    Full Text Available The article presents the results of surface test of composite shaped in the permanent mould casting process. As part of the research anddevelopment project realized in the Department of Materials Technology at the Silesian University of Technology, a pilot plant scale stand was built to manufacture of more than 50 kg suspensions in a single technological cycle. Made in industrial conditions castings to form in the five inner core mould mounted in GM110 permanent mould casting machine confirmed the possibility of the shaping the composite pistons. Castings made from composite suspension AlSi7Mg/SiC and AlSi7Mg/SiC + Cg according to the technology procedure were classified as correct and devoted to the proper machining forming working surfaces of the piston to the air compressor. Comparative tests were performed for the casting of unreinforced AlSi7Mg alloy and composite castings. To assess the ability to fill the mold cavity and the accuracy of mapping used in contour shape FRT analysis of the distance between the grooves on the surface of the piston skirt. Studies have confirmed the differences in the fluidity of alloy matrix and composites suspensions. The difference in the accuracy of the dimensional mapping mould does not disqualify of composite materials, all castings are classified as correct and used for machining.

  14. Maximum Work of Free-Piston Stirling Engine Generators

    Science.gov (United States)

    Kojima, Shinji

    2017-04-01

    Using the method of adjoint equations described in Ref. [1], we have calculated the maximum thermal efficiencies that are theoretically attainable by free-piston Stirling and Carnot engine generators by considering the work loss due to friction and Joule heat. The net work done by the Carnot cycle is negative even when the duration of heat addition is optimized to give the maximum amount of heat addition, which is the same situation for the Brayton cycle described in our previous paper. For the Stirling cycle, the net work done is positive, and the thermal efficiency is greater than that of the Otto cycle described in our previous paper by a factor of about 2.7-1.4 for compression ratios of 5-30. The Stirling cycle is much better than the Otto, Brayton, and Carnot cycles. We have found that the optimized piston trajectories of the isothermal, isobaric, and adiabatic processes are the same when the compression ratio and the maximum volume of the same working fluid of the three processes are the same, which has facilitated the present analysis because the optimized piston trajectories of the Carnot and Stirling cycles are the same as those of the Brayton and Otto cycles, respectively.

  15. They shall wear fringes.

    Science.gov (United States)

    Sugar, M

    1999-01-01

    The multiple functions of clothes include utility, protection, rivalry, disguise, camouflage, display for seduction purposes, aggression, totemism, and status. Here the focus is on a decorative and distinctive hierarchical aspect of ancient dress, the tsitsit or fringes, whose original function is long absent, but that has endured for 3,500 years in Judaism. The beginning of their use beyond the totemic appears related to issues of changing identity from slavery to liberty, endowing noble status, exhibitionism, a symbol of identity, identification with the aggressor, a talisman, and potency. It is conceptualized that they became a symbol, or a specifier, that helped promote group cohesion in ex-slaves who were frightened, dependent, anxious, and not hopeful about their future. The tsitsit aided the development of a new identity and made all Israelites equal and noble to the observer. The durability of this symbol to the present is evident in its daily wear, as an accompaniment to daily prayers, as well as in its use as a burial shroud for males. It appears that the tsitsit have additional multiple functions. These are the promise of oral and genital satisfaction, and the pleasure of the after-life, superego warnings and control of sexual impulses, protection, survival value, and affirmation. Since they offer sublimation with acceptable gratification of instincts, the tsitsit have become ritualized and endure.

  16. Ring interferometry

    CERN Document Server

    Malykin, Grigorii B; Zhurov, Alexei

    2013-01-01

    This monograph is devoted to the creation of a comprehensive formalism for quantitative description of polarized modes' linear interaction in modern single-mode optic fibers. The theory of random connections between polarized modes, developed in the monograph, allows calculations of the zero shift deviations for a fiber ring interferometer. The monograph addresses also the

  17. Intelligent Detection of Drill Wear

    Science.gov (United States)

    Liu, T. I.; Chen, W. Y.; Anatharaman, K. S.

    1998-11-01

    Backpropagation neural networks (BPNs) were used for on-line detection of drill wear. The neural network consisted of three layers: input, hidden, and output. The input vector comprised drill size, feed rate, spindle speed, and eight features obtained by processing the thrust and torque signals. The output was the drill wear state which either usable or failure. Drilling experiments with various drill sizes, feed rates and spindle speeds were carried out. The learning process was performed effectively by utilising backpropagation with smoothing and an activation function slope. The on-line detection of drill wear states using BPNs achieved 100% reliability even when the drill size, feed rate and spindle speed were changed. In other words, the developed on-line drill wear detection systems have very high robustness and hence can be used in very complex production environments, such as flexible manufacturing systems.

  18. Wear resistance properties of austempered ductile iron

    Science.gov (United States)

    Lerner, Y. S.; Kingsbury, G. R.

    1998-02-01

    A detailed review of wear resistance properties of austempered ductile iron (ADI) was undertaken to examine the potential applications of this material for wear parts, as an alternative to steels, alloyed and white irons, bronzes, and other competitive materials. Two modes of wear were studied: adhesive (frictional) dry sliding and abrasive wear. In the rotating dry sliding tests, wear behavior of the base material (a stationary block) was considered in relationship to countersurface (steel shaft) wear. In this wear mode, the wear rate of ADI was only one-fourth that of pearlitic ductile iron (DI) grade 100-70-03; the wear rates of aluminum bronze and leaded-tin bronze, respectively, were 3.7 and 3.3 times greater than that of ADI. Only quenched DI with a fully martensitic matrix slightly outperformed ADI. No significant difference was observed in the wear of steel shafts running against ADI and quenched DI. The excellent wear performance of ADI and its countersurface, combined with their relatively low friction coefficient, indicate potential for dry sliding wear applications. In the abrasive wear mode, the wear rate of ADI was comparable to that of alloyed hardened AISI 4340 steel, and approximately one-half that of hardened medium-carbon AISI 1050 steel and of white and alloyed cast irons. The excellent wear resistance of ADI may be attributed to the strain-affected transformation of high-carbon austenite to martensite that takes place in the surface layer during the wear tests.

  19. The Delamination Theory of Wear

    Science.gov (United States)

    1974-09-01

    junctions, it is still based on the assumption that the deformation occurs at the asperities. Rabinowicz [14] advanced an adhesion theory of friction...shown that bronze particles were indeed bigger than steel particles. The compilation of wear particle sizes given by Rabinowicz [14] also indicates...Waterhouse [32] has shown that, in fact, fretting occurs by delamination. 6) Minimum Load for Loose Particle Formation Rabinowicz [14] found that no wear

  20. The fractal characterization of wear particles in relation to the wear status

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The topography and distribution of wear particles produced in the wear process containmuch information about the wear status. Fractal geometry is applied in this paper to describe thewear particle accumulation in order to characterize the wear status change. The sliding wear test isperformed on a pin-on-disc apparatus using steel disc and brass pin. The investigation resultsshow that wear particle accumulation presents a strong bi-fractal behavior. Also, the fractal dimen-sion varies in correspondence to the wear status change. A new fractal index characterizing thewear particle accumulation is put forward. The wear tests of brass pin demonstrate that the fractalindex is effective in describing the wear status change.

  1. Wear behaviour of Al 261

    Directory of Open Access Journals (Sweden)

    N. Mathan Kumar

    2016-03-01

    Full Text Available Al 2618 matrix material was mixed with the Silicon Nitride (Si3N4, Aluminium Nitride (AlN and Zirconium Boride (ZrB2 reinforced particles. AMC was synthesized successfully by the stir casting method with the various X-wt.% of reinforcements (X = 0,2,4,6,8. Tribological behaviour was studied in this composite with various temperature conditions. The working conditions were Temperature (°C, Load (N, Velocity (m/s and Sliding Distances (m. Before wear testing the mechanical behaviour has been analysed. EDAX was confirmed by the matrix material composition. The Al 2618 alloy and the reinforcement mixers were confirmed by the X-ray Diffraction analysis. Wear rate (mm3/m, Wear resistance (m/mm3, Specific Wear rate (m/Nm and Co-efficient of friction (μ were analysed with various conditions. The worn surfaces were analysed before and after wear testing by Scanning Electron Microscope (SEM. Influence of process parameters and Percentage of contribution were analysed by Taguchi and Analysis of Variance (ANOVA methods. Genetic Algorithm (GA was adopted for optimizing the best and mean of the wear rate and to identify the exact influence of input parameters.

  2. Critical component wear in heavy duty engines

    CERN Document Server

    Lakshminarayanan, P A

    2011-01-01

    The critical parts of a heavy duty engine are theoretically designed for infinite life without mechanical fatigue failure. Yet the life of an engine is in reality determined by wear of the critical parts. Even if an engine is designed and built to have normal wear life, abnormal wear takes place either due to special working conditions or increased loading.  Understanding abnormal and normal wear enables the engineer to control the external conditions leading to premature wear, or to design the critical parts that have longer wear life and hence lower costs. The literature on wear phenomenon r

  3. On SAP-rings

    OpenAIRE

    Zhixiang, Wu

    2006-01-01

    The rings whose simple right modules are absolutely pure are called right $SAP$-rings. We give a new characterization of right $SAP$ rings, right $V$ rings, and von Neumann regular rings. We also obtain a new decomposition theory of right selfinjective von Neumann regular rings. The relationships between $SAP$-rings, $V$-rings, and von Neumann regular rings are explored. Some recent results obtained by Faith are generalized and the results of Wu-Xia are strengthened.

  4. Piston surface heat transfer during combustion in large marine diesel engines

    DEFF Research Database (Denmark)

    Jensen, Michael Vincent; Walther, Jens Honore

    2010-01-01

    In the design process of large marine diesel engines information on the maximum heat load on the piston surface experienced during the engine cycle is an important parameter. The peak heat load occurs during combustion when hot combustion products impinge on the piston surface. Although the maximum...... with burning off piston surface material. In this work the peak heat load on the piston surface of large marine diesel engines during combustion was investigated. Measurements of the instantaneous surface temperature and surface heat flux on pistons in large marine engines are difficult due to expensive...... was calculated under different conditions in the numerical setup in order to obtain information of the actual peak heat flux experienced at the piston in large marine diesel engines during combustion. The variation of physical parameters influencing the heat transfer during combustion included a variation...

  5. Development of a Collins-type cryocooler floating piston control algorithm

    Science.gov (United States)

    Hogan, Jake; Hannon, Charles L.; Brisson, John

    2012-06-01

    The Collins-type cryocooler uses a floating piston design for the working fluid expansion. The piston floats between a cold volume, where the working fluid is expanded, and a warm volume. The piston is shuttled between opposite ends of the closed cylinder by opening and closing valves connecting several reservoirs at various pressures to the warm volume. Ideally, these pressures should be distributed between the high and low system pressure to gain good control of the piston motion. In this work, a numerical quasi-steady thermodynamic model is developed for the piston cycle. The model determines the steady state pressure distribution of the reservoirs for a given control algorithm. The results are then extended to show how valve timing modifications can be used to overcome helium leakage past the piston during operation.

  6. a Simple Model to Estimate the Impact Force Induced by Piston Slap

    Science.gov (United States)

    CHO, S.-H.; AHN, S.-T.; KIM, Y.-H.

    2002-08-01

    The dynamics of piston's secondary motion (lateral and rotational motion) across the clearance between piston and cylinder inner wall of reciprocating machines are analyzed. This paper presents an analytical model, which can predict the impact forces and vibratory response of engine block surface induced by the piston slap of an internal combustion engine. A piston is modelled on a three-degree-of-freedom system to represent its planar motion. When slap occurs, the impact point between piston skirt and cylinder inner wall is modelled on a two-degree-of-freedom vibratory system. The equivalent parameters such as mass, spring constant, and damping constant of piston and cylinder inner wall are estimated by using measured (driving) point mobility. Those parameters are used to calculate the impact force and for estimating the vibration level of engine block surfaces. The predicted results are compared with experimental results to verify the model.

  7. Mixed Lubrication Analysis and Experiment Validation of Internal Combustion Piston Skirt

    Institute of Scientific and Technical Information of China (English)

    杨俊伟; 于旭东; 王成焘; 谢友柏

    2004-01-01

    A mixed lubrication model was established for piston skirt lubrication. The mathematical model developed in this paper incorporates governing equations of motion with average Reynolds equation. This model considers the surfaceroughness and profile. The corresponding computer program can be used to calculate oscillatory motion of piston during the entire trajectory, which has the excellent convergence.In addition, a set of equipment, which adopt the laser induced fluorescent method, was developed to measure the oil film thickness between the piston and the bore.

  8. Thermal Stress Analysis of a Speculative IC Engine Piston using CAE Tools

    Directory of Open Access Journals (Sweden)

    Hitesh pandey

    2014-11-01

    Full Text Available This paper deals with the pressure due to expanding combustion gases in the combustion chamber space at the top of the cylinder which generate thermal stresses due to presence of heat involved on the reciprocating masses. The present work deals with the use of different materials for IC engine piston and a comparative study is made to achieve the best possible result. Piston parameters are taken using the conventional formulas and are constant throughout the analysis. Moreover the boundary conditions are chosen such that the piston does not moves sideways except in the direction of line of action of the piston itself.

  9. Assessment of 25 kW free-piston Stirling technology alternatives for solar applications

    Science.gov (United States)

    Erbeznik, Raymond M.; White, Maurice A.; Penswick, L. B.; Neely, Ronald E.; Ritter, Darren C.; Wallace, David A.

    The final design, construction, and testing of a 25-kW free-piston advanced Stirling conversion system (ASCS) are examined. The final design of the free-piston hydraulic ASCS consists of five subsystems: heat transport subsystem (solar receiver and pool boiler), free-piston hydraulic Stirling engine, hydraulic subsystem, cooling subsystem, and electrical and control subsystem. Advantages and disadvantages are identified for each technology alternative. Technology alternatives considered are gas bearings vs flexure bearings, stationary magnet linear alternator vs moving magnetic linear alternator, and seven different control options. Component designs are generated using available in-house procedures to meet the requirements of the free-piston Stirling convertor configurations.

  10. Wear-resistant ball bearings for space applications. [coated with titanium carbide

    Science.gov (United States)

    Boving, H.; Hintermann, H. E.; Haenni, W.; Bondivenne, E.; Boeto, M.; Conde, M.

    1977-01-01

    Ball bearings for hostile environments were developed. They consist of normal ball bearing steel parts of which the rings are coated with hard, wear-resistant, chemical vapor deposited (C.V.D) TiC. Experiments in ultrahigh vacuum, using cages of various materials with self-lubricating properties, have shown that such bearings are suitable for space applications.

  11. Vacuum stress and closed paths in rectangles, pistons and pistols

    Science.gov (United States)

    Fulling, S. A.; Kaplan, L.; Kirsten, K.; Liu, Z. H.; Milton, K. A.

    2009-04-01

    Rectangular cavities are solvable models that nevertheless touch on many of the controversial or mysterious aspects of the vacuum energy of quantum fields. This paper is a thorough study of the two-dimensional scalar field in a rectangle by the method of images, or closed classical (or optical) paths, which is exact in this case. For each point r and each specularly reflecting path beginning and ending at r, we provide formulae for all components of the stress tensor Tμν(r), for all values of the curvature coupling constant ξ and all values of an ultraviolet cutoff parameter. Arbitrary combinations of Dirichlet and Neumann conditions on the four sides can be treated. The total energy is also investigated, path by path. These results are used in an attempt to clarify the physical reality of the repulsive (outward) force on the sides of the box predicted by calculations that neglect both boundary divergences and the exterior of the box. Previous authors have studied 'piston' geometries that avoid these problems and have found the force to be attractive. We consider a 'pistol' geometry that comes closer to the original problem of a box with a movable lid. We find again an attractive force, although its origin and detailed behavior are somewhat different from the piston case. However, the pistol (and the piston) model can be criticized for extending idealized boundary conditions into short distances where they are physically implausible. Therefore, it is of interest to see whether leaving the ultraviolet cutoff finite yields results that are more plausible. We then find that the force depends strongly on a geometrical parameter; it can be made repulsive, but only by forcing that parameter into the regime where the model is least convincing physically.

  12. Modeling and Simulation of Aerial Dispersion on Piston Dispersal Mechanism%Modeling and Simulation of Aerial Dispersion on Piston Dispersal Mechanism

    Institute of Scientific and Technical Information of China (English)

    陶如意; 王浩; 黄蓓

    2011-01-01

    For the aerial dispersing interior ballistic process and submunition exterior ballistic initial conditions of cluster munition with piston maximum travel limit, a novel model is established, and the numerical simulation is performed. The piston maximum travel limit and the effect of reaction force on carrier body are researched using the internal ballistic model. Guide tube, cluster munition rotating and submunition assembly are analyzed using the submunition initial external ballistic model. The computational results are consistent with the practical process and the experimental data, and prove the rationality of this model. The theoretical methods are presented for the construction design and dispersion analysis of piston dispersal mechanism.

  13. Observation of Oil Flow Characteristics in Rolling Piston Rotary Compressor for Reducing Oil Circulation Rate

    Science.gov (United States)

    Song, S. j.; Noh, K. Y.; Min, B. C.; Yang, J. S.; Choi, G. M.; Kim, D. J.

    2015-08-01

    The oil circulation rate (OCR) of the rolling piston rotary compressor is a significant factor which affects the performance of refrigeration system. The increase of oil discharge causes decreasing of the heat transfer efficiency in the heat exchanger, pressure drop and lack of oil in lubricate part in compressor. In this study, the internal flow of compressor was visualized to figure out the oil droplet flow characteristics. The experiments and Computational Fluid Dynamics (CFD) simulations were conducted in various frequency of compressor to observe the effect of operation frequency on oil droplet flow characteristics for reducing OCR. In situ, measurement of oil droplet diameter and velocity were conducted by using high speed image visualization and Particle Image Velocimetry (PIV). The flow paths were dominated by copper wire parts driving the motor which was inserted in compressor. In order to verify the reliability of CFD simulation, the tendency of oil flow characteristics in each flow path and the compressor operating conditions were applied in CFD simulation. For reducing OCR, the structure such as vane, disk and ring is installed in the compressor to restrict the main flow path of oil particle. The effect of additional structure for reducing OCR was evaluated using CFD simulation and the results were discussed in detail.

  14. Free-Piston Stirling Machine for Extreme Temperatures

    Science.gov (United States)

    Wood, James Gary (Inventor)

    2013-01-01

    A free piston Stirling machine including a thermal buffer tube extending from the machine's expansion space and surrounded by its heat rejector and its regenerator, a displacer cylinder extending from the thermal buffer tube to the compression space and surrounded by the heat rejecting heat exchanger, and a displacer that reciprocates within an excursion limit that extends into the regenerator by no more than 20% of the length of the regenerator during normal operation and preferably within excursion limits that are substantially the length of the heat rejector.

  15. Piston cylinder cell for high pressure ultrasonic pulse echo measurements

    Science.gov (United States)

    Kepa, M. W.; Ridley, C. J.; Kamenev, K. V.; Huxley, A. D.

    2016-08-01

    Ultrasonic techniques such as pulse echo, vibrating reed, or resonant ultrasound spectroscopy are powerful probes not only for studying elasticity but also for investigating electronic and magnetic properties. Here, we report on the design of a high pressure ultrasonic pulse echo apparatus, based on a piston cylinder cell, with a simplified electronic setup that operates with a single coaxial cable and requires sample lengths of mm only. The design allows simultaneous measurements of ultrasonic velocities and attenuation coefficients up to a pressure of 1.5 GPa. We illustrate the performance of the cell by probing the phase diagram of a single crystal of the ferromagnetic superconductor UGe2.

  16. Prediction for Outlet Noise of Rolling Piston Comperssor

    Directory of Open Access Journals (Sweden)

    Zhang Tieshan

    2015-01-01

    Full Text Available An acoustic wave equation with considering small perturbation is presented first by use of the fluidic mechanics and aerodynamics, then a theoretical model for predicting the outlet noise of rolling piston compressors is investigated, and the sound pressure and sound power of the outlet noise are formulated based on the acoustic wave equation. The experimental data and simulation results for the outlet noise with different rotation velocities have been compared with the discrepancy less than 2.6%, which verifies the approach presented in this paper.

  17. β Style Free-Piston Stirling Engine Control System Research

    Directory of Open Access Journals (Sweden)

    Xu Jian

    2016-01-01

    Full Text Available For the Free-Piston Stirling Engines (FPSE control system, a three -phase bridge circuit is reused as the system output about rectifier and start inverter. When FPSE system is in the power stage, the double closed loop control strategy and optimization algorithm of PI control parameters is adopted to ensure the highest system transmission efficiency under the requirements of the system output power and guarantee the stability of the running system. The simulation results prove the effectiveness of the above research content.

  18. Wear and corrosion resistance of laser remelted and plasma sprayed Ni and Cr coatings on copper

    Institute of Scientific and Technical Information of China (English)

    梁工英; 黄俊达; 安耿

    2004-01-01

    Nickel and chromium coatings were produced on the copper sheet using plasma spraying and laser remelting. The sliding wear test was achieved on a block-on-ring tester and the corrosion test was carried out in an acidic atmosphere. The corrosive behaviors of both coatings and original copper samples were investigated by using an impedance comparison method. The experimental results show that the nickel and chromium coatings display better wear resistance and corrosion resistance relative to the original pure copper sample. The wear resistance of the coatings is 8 - 12 times as large as original samples, and the wear resistance of laser remelted samples is better than that of plasma sprayed ones. The corrosion resistance of laser remelted nickel and chromium samples is better than that of plasma sprayed samples respectively. The corrosion rate of chromium coatings is less than that of nickel coatings, and the laser remelted Cr coating exhibits the least corrosion rate.

  19. Calculation of wear (f.i. wear modulus) in the plastic cup of a hip joint prosthesis

    NARCIS (Netherlands)

    Ligterink, D.J.

    1975-01-01

    The wear equation is applied to the wear process in a hip joint prosthesis and a wear modulus is defined. The sliding distance, wear modulus, wear volume, wear area, contact angle and the maximum normal stress were calculated and the theoretical calculations applied to test results. During the wear

  20. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2014-01-06

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  1. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2016-01-06

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  2. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2015-01-07

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  3. Wear behavior of an austempered ductile iron containing Mo-Ni-Cu

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, S.; Rahimi, M.A. [Faculty of Materials Engineering, Sahand Univ. of Technology, Tabriz (Iran)

    2005-07-01

    The aim of the this investigation is to study the influence of Ni on tribiological behavior of an austempered ductile iron (ADI) containing Mo, Ni and Cu. Ductile irons with chemical composition Fe-3.56%C-2.67%Si -0.25%Mo-0.5%Cu and Ni contents of 0.8 and 1.5% were cast into standard Y-blocks. Wear test samples were machined off from the bottom section of blocks. Austenitizing heat treatment was carried out at 870 C temperature followed by austempering at 270, 320, and 370 C for 5-1140 minutes. The wear test was carried out by using block-on-ring test machine. Sliding dry wear behavior was studied under applied loads of 50, 100 and 150 N. The results show that wear resistance is independent of austempering temperature with an applied load of 50 N, but there is a strong dependence at higher austempering temperatures with applied loads of 100 and 150 N. Wear mechanism is described as being due to subsurface fatigue, with cracks nucleated at plastically, deformed graphite interfaces. The wear controlling mechanism is the crack growth when wear shows a dependence on applied load and austempering temperature. (orig.)

  4. Influence of graphite content on sliding wear characteristics of CNTs-Ag-G electrical contact materials

    Institute of Scientific and Technical Information of China (English)

    WANG Juan; FENG Yi; LI Shu; LIN Shen

    2009-01-01

    CNTs-Ag-G electrical contact composite material was prepared by means of powder metallurgical method. The influence of the graphite content on sliding wear characteristics of electrical contact levels was examined. In experiments, CNTs content was retained as 1% (mass fraction), and graphite was added at content levels of 8%, 10%, 13%, 15% and 18%, respectively. The results indicate that with the increase of graphite content, the contact resistance of electrical contacts is enhanced to a certain level then remains constant. Friction coefficient decreases gradually with the increase of graphite content. Wear mass loss decreases to the minimum value then increases. With the small content of graphite, the adhesive wear is hindered, which leads to the decrease of wear mass loss, while excessive graphite brings much more worn debris, resulting in the increase of mass loss. It is concluded that wear mass loss reaches the minimum value when the graphite mass fraction is about 13%. Compared with conventional Ag-G contact material, the wear mass loss of CNTs-Ag-G composite is much less due to the obvious increase of hardness and electrical conductivity, decline of friction surface temperature and inhibition of adhesive wear between composites and slip rings.

  5. Origami rings

    CERN Document Server

    Buhler, Joe; de Launey, Warwick; Graham, Ron

    2010-01-01

    Motivated by a question in origami, we consider sets of points in the complex plane constructed in the following way. Let $L_\\alpha(p)$ be the line in the complex plane through $p$ with angle $\\alpha$ (with respect to the real axis). Given a fixed collection $U$ of angles, let $\\RU$ be the points that can be obtained by starting with $0$ and $1$, and then recursively adding intersection points of the form $L_\\alpha(p) \\cap L_\\beta(q)$, where $p, q$ have been constructed already, and $\\alpha, \\beta$ are distinct angles in $U$. Our main result is that if $U$ is a group with at least three elements, then $\\RU$ is a subring of the complex plane, i.e., it is closed under complex addition and multiplication. This enables us to answer a specific question about origami folds: if $n \\ge 3$ and the allowable angles are the $n$ equally spaced angles $k\\pi/n$, $0 \\le k < n$, then $\\RU$ is the ring $\\Z[\\zeta_n]$ if $n$ is prime, and the ring $\\Z[1/n,\\zeta_{n}]$ if $n$ is not prime, where $\\zeta_n := \\exp(2\\pi i/n)$ is ...

  6. Erosive Wear and Wear Mechanism of in situ TiCp/Fe Composites

    Institute of Scientific and Technical Information of China (English)

    Zhaojing LIU; Zhiliang NING; Fengzhen LI; Xiurong YAO; Shanzhi REN

    2005-01-01

    The base structure of in situ TiCP/Fe composites fabricated under industrial condition was changed by different heat treatments. Erosive wear tests were carried out and the results were compared with that of wear-resistant white cast iron. The results suggest that the wear resistance of the in situ TiCp/Fe composite is higher than that of wear-resistant white cast iron under the sand erosive wear condition. The wear mechanism of the wear-resistant white cast iron was a cycle process that base surface was worn and carbides were exposed, then carbides was broken and wear pits appeared. While the wear mechanism of in situ TiCp/Fe composite was a cycle process that base surface was worn and TiC grains were exposed and dropped. The wear resistance of in situ TiCp/Fe composite was lower than that of wear-resistant white cast iron under the slurry erosive wear condition. Under such circumstance,the material was not only undergone erosive wear but also electrochemistry erosion due to the contact with water in the medium. The wear behaviours can be a combination of two kinds of wear and the sand erosive wear is worse than slurry erosive wear.

  7. A free-piston Stirling cryocooler using metal diaphragms

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-12-01

    A novel concept for a free-piston Stirling cryocooler has been proposed. The concept uses a pair of metal diaphragms to seal and suspend the displacer of a free-piston Stirling cryocooler. The diaphragms allow the displacer to move without rubbing or moving seals, potentially resulting in a long-life mechanism. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicates the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. Sage predicted the macroscopic behaviour of the prototype well but did not provide sufficient insights to improve performance significantly. This paper presents details of the development, modelling and testing of the proof-of-concept prototype and a second, improved prototype.

  8. The low-cost and precise piston gas pressure regulator

    Science.gov (United States)

    Kudasik, Mateusz; Skoczylas, Norbert

    2016-03-01

    The present paper discusses the concept and functioning of an innovative instrument for precise stabilization of gas pressure. The piston gas pressure regulator was constructed at the Strata Mechanics Research Institute of the Polish Academy of Sciences. The tests to which the instrument was subjected involved observing the values of stabilized pressure at the level of 10 bar and 3 bar, for various gas flow rates at the outlet of the instrument. The piston gas pressure regulator operates within the range of 0-10 bar and the gas flow range of 0-240 cm3 min-1. The precision of the process of stabilizing the initial pressure is  ±0.005 bar, regardless of the gas pressure value and the flow rate observed at the outlet of the instrument. Although the pressure transducer’s accuracy is 0.25% of the full range, the conducted tests of the regulator demonstrated that the obtained changeability of the stabilized pressure is at least two times lower. Unlike some other gas pressure regulators available on the market, the instrument constructed by the authors of the present paper is highly precise when it comes to the process of stabilization, and inexpensive to build.

  9. Real-time estimation of differential piston at the LBT

    Science.gov (United States)

    Böhm, Michael; Pott, Jörg-Uwe; Sawodny, Oliver; Herbst, Tom; Kürster, Martin

    2014-07-01

    In this paper, we present and compare different strategies to minimize the effects of telescope vibrations to the differential piston (OPD) for LINC/NIRVANA at the LBT using an accelerometer feedforward compensation approach. We summarize why this technology is of importance for LINC/NIRVANA, but also for future telescopes and instruments. We outline the estimation problem in general and its specifics at the LBT. Model based estimation and broadband filtering techniques can be used to solve the estimation task, each having its own advantages and disadvantages, which will be discussed. Simulation results and measurements at the LBT are shown to motivate and support our choice of the estimation algorithm for the instrument LINC/NIRVANA. We explain our laboratory setup aimed at imitating the vibration behaviour at the LBT in general, and the M2 as main contributor in particular, and we demonstrate the controller's ability to suppress vibrations in the frequency range of 8 Hz to 60 Hz. In this range, telescope vibrations are the most dominant disturbance to the optical path. For our measurements, we introduce a disturbance time series which has a frequency spectrum comparable to what can be measured at the LBT on a typical night. We show promising experimental results, indicating the ability to suppress differential piston induced by telescope vibrations by a factor of about 5 (RMS), which is significantly better than any currently commissioned system.

  10. Advanced Controller Developed for the Free-Piston Stirling Convertor

    Science.gov (United States)

    Gerber, Scott S.

    2005-01-01

    A free-piston Stirling power convertor is being considered as an advanced power-conversion technology for future NASA deep-space missions requiring long-life radioisotope power systems. The NASA Glenn Research Center has identified key areas where advanced technologies can enhance the capability of Stirling energy-conversion systems. One of these is power electronic controls. Current power-conversion technology for Glenn-tested Stirling systems consists of an engine-driven linear alternator generating an alternating-current voltage controlled by a tuning-capacitor-based alternating-current peak voltage load controller. The tuning capacitor keeps the internal alternator electromotive force (EMF) in phase with its respective current (i.e., passive power factor correction). The alternator EMF is related to the piston velocity, which must be kept in phase with the alternator current in order to achieve stable operation. This tuning capacitor, which adds volume and mass to the overall Stirling convertor, can be eliminated if the controller can actively drive the magnitude and phase of the alternator current.

  11. New 5 Kilowatt Free-piston Stirling Space Convertor Developments

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Chapman, Peter A., Jr.

    2007-01-01

    The NASA Vision for Exploration of the moon may someday require a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kW. In the 1990s, Mechanical Technology Inc. s Stirling Engine Systems Division (some of whose Stirling personnel are now at Foster-Miller, Inc.) developed a 25 kW free piston Stirling Space Power Demonstrator Engine under the SP-100 program. This system consisted of two 12.5 kW engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA and DoE have been developing dual 55 W and 80 W Stirling convertor systems for potential use with radioisotope heat sources. Total test times of all convertors in this effort exceed 120,000 hours. Recently, NASA began a new project with Auburn University to develop a 5 kW, single convertor for potential use in a lunar surface reactor power system. Goals of this development program include a specific power in excess of 140 W/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Auburn University awarded a subcontract to Foster-Miller, Inc. to undertake development of the 5 kW Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  12. Focused, phased-array plane piston and spherically-shaped concave piston transducers: comparison for the same aperture and focal point.

    Science.gov (United States)

    Warriner, Renée K; Cobbold, Richard S C

    2012-04-01

    It has sometimes been assumed that the phased-array plane piston transducer and the spherically-shaped concave piston transducer are equivalent structures when both have the same aperture and focal point. This assumption has not been previously examined, nor has an expression for the on-axis impulse response of the focused, phased-array plane piston transducer been derived. It is shown in this paper how such an expression can be obtained. Comparisons of the impulse response for both structures show similarities, as well as some differences that could be significant as the observation point approaches the focal point. Comparisons are also performed for wide-band pulses close to the focus as well as for sinusoidal excitation. A physical explanation for the cause of the impulse response discrepancy is shown to be due to the nature of the piston focusing delay and its effect on the Rayleigh integral.

  13. Analysis and Modelling of Electrode Wear in Resistance Spot Welding

    DEFF Research Database (Denmark)

    Madsen, Anders; Pedersen, Kim; Friis, Kasper Storgaard

    2010-01-01

    A model describing electrode wear as a function of weld number, initial tip diameter, truncated cone angle, welding current and electrode force is proposed. Excellent agreement between the model and experimental results is achieved, showing that the model can describe the change in electrode tip ...... a central cavity is formed and one where smaller pits are formed randomly across the electrode face. The influence of these two types of surface pits on the nugget size are investigated using the FE code SORPAS, revealing ring welds and undersized weld nuggets....

  14. Directionality of sperm whale sonar clicks and its relation to piston radiation theory

    DEFF Research Database (Denmark)

    Beedholm, K.; Møhl, Bertel

    2006-01-01

    with the spatial impulse response of a piston. The angle of a recorded click can be estimated as the angle producing the spatial impulse response that gives the best match with the observation when convolved with the on-axis wave form. It is concluded that piston theory applies to sperm whale sonar click emission....

  15. Scavenge flow analysis of opposed-piston two-stroke engine based on dynamic characteristics

    Directory of Open Access Journals (Sweden)

    Fu-kang Ma

    2015-04-01

    Full Text Available Opposed-piston two-stroke engine has been proposed by Beijing Institute of Technology to improve power density and complete machine balance relative to conventional engines. In order to study opposed-piston two-stroke engine scavenging flow, a scavenging system was configured using a three-dimensional computational fluid dynamics model effectively coupled to experiments. The boundary conditions are obtained through one-dimensional working process simulation results and experiments. As the opposed-piston relative dynamic characteristics of opposed-piston two-stroke engine depend on different design and operating parameters including the opposed-piston motion phase difference and crank-connecting rod ratio, a numerical simulation program was built using MATLAB/Simulink to define opposed-piston motion profiles based on equivalent crank angle of opposed crank-connecting rod mechanism. The opposed-piston motion phase difference only affects scavenging timing while crank-connecting rod ratio affects scavenging timing and duration. Scavenging timing and duration are the main factors which affect scavenging performance. The results indicate that a match of opposed-piston motion phase difference and crank-connecting rod ratio has the potential to achieve high scavenging and trapping efficiency with a right flow in cylinder.

  16. Investigations of piston motion in transverse and longitudinal direction; Untersuchung der Kolbenbewegung in Motorquer- und Motorlaengsrichtung

    Energy Technology Data Exchange (ETDEWEB)

    Kuenzel, R.

    1997-12-31

    The book reviews literature on piston motion and presents a newly developed measuring and evaluation method in which the piston motion is recorded by probes inside the cylinder tube. All stages are represented, from the original lubricating gap signal to the calculated piston shaft load pattern. Using a variety of experimental findings, it is shown how the noise of longitudinal and transverse piston motion can be reduced. Influencing parameters such as piston shape, piston bolt axial displacement, piston bolt clearance, connecting rod stiffness and production-dpendent nonsymmetries of the connecting rod and piston are gone into. (orig./AKF) [Deutsch] Das Buch gibt einen Ueberblick ueber die Behandlung der Kolbenbewegung in der Literatur und stellt ein speziell entwickeltes Mess- und Auswerteverfahren vor, bei dem die raeumliche Bewegung des Kolbens durch Sensoren im Zylinderrohr erfasst wird. Die Darstellungen enthalten alle Schritte vom urspruenglich gemessenen Schmierspaltsignal bis hin zum errechneten Tragbild am Kolbenschaft. Anhand von vielzaehligen Versuchsergebnissen wird aufgezeigt, wie beim Dieselmotor auf die Bewegung des Kolbens in Motorquer- und Motorlaengsrichtung akustisch guenstig Einfluss genommen werden kann. Es werden Einflussparameter wie Kolbenform, Kolbenbolzendesachsierung, Spielgebung am Kolbenbolzen, Pleuelsteifigkeit und diverse fertigungsbedingte Bauteilunsymmetrien an Pleuel und Kolben behandelt. (orig./AKF)

  17. Computer Aided Design of Kaplan Turbine Piston with\tSolidWorks

    Directory of Open Access Journals (Sweden)

    Camelia Jianu

    2010-10-01

    Full Text Available The paper presents the steps for 3D computer aided design (CAD of Kaplan turbine piston made in SolidWorks.The present paper is a tutorial for a Kaplan turbine piston 3D geometry, which is dedicaded to the Parts Sketch and Parts Features design and Drawing Geometry and Drawing Annotation.

  18. Should School Nurses Wear Uniforms?

    Science.gov (United States)

    Journal of School Health, 2001

    2001-01-01

    This 1958 paper questions whether school nurses should wear uniforms (specifically, white uniforms). It concludes that white uniforms are often associated with the treatment of ill people, and since many people have a fear reaction to them, they are not necessary and are even undesirable. Since school nurses are school staff members, they should…

  19. Tooth wear patterns in the deciduous dentition.

    Science.gov (United States)

    Warren, John J; Yonezu, Takuro; Bishara, Samir E

    2002-12-01

    Tooth wear is common in the deciduous dentition. A recent study suggests that tooth wear in the deciduous dentition is related to subsequent tooth wear in adults, so that early identification of factors related to tooth wear could be of long-term benefit. The purposes of this study were to describe patterns of tooth wear in the deciduous dentition and to relate tooth wear to occlusal characteristics and longitudinal dietary patterns. Data were collected as part of a longitudinal study of a cohort of children recruited at birth from Iowa hospitals. Stone casts were obtained in the deciduous dentition stage, and 355 children, 4 to 5 years old, met the selection criteria. Tooth wear was categorized for each tooth as none, mild, moderate, or severe, and related to occlusal characteristics and longitudinal data on fruit juice and soft drink consumption. All children exhibited some tooth wear on at least 1 tooth, and nearly 16% of them had at least 1 tooth with severe wear. Tooth wear was generally more severe in the maxillary arch and the anterior teeth. Severe tooth wear on the molars was significantly related to posterior crossbites, but severe tooth wear on the incisors was related to Class III canine relationships. There were no statistically significant relationships between tooth wear and soft drink or fruit juice consumption. Based on our results, we concluded that mild tooth wear is universal in the deciduous dentition, but only a few occlusal factors are related to severe tooth wear. Tooth wear was not related to any dietary patterns we investigated.

  20. Demonstration of a free piston Stirling engine driven linear alternator, phase I report

    Energy Technology Data Exchange (ETDEWEB)

    Goldwater, B.; Piller, S.; Rauch, J.; Cella, A.

    1977-03-30

    The results of the work performed under Phase I of the free piston Stirling engine demonstrator program are described. The objective of the program is to develop a 2 kW free piston Stirling engine/linear alternator energy conversion system, for an isotopic heat source, with a greater than 30% overall efficiency. Phase I was a 15-month effort to demonstrate the feasibility of the system through analysis and experimental testing of the individual components. An introduction to Stirling engines and the details of the tasks completed are presented in five major sections: (1) introduction to Stirling engine; (2) preliminary design of an advanced free piston Stirling demonstrator engine; (3) design and test of a 1 kWE output linear alternator; (4) test of a model free piston Stirling engine; and (5) development of a free piston Stirling engine computer simulation code.

  1. Improvements of harrows wear resistance

    Directory of Open Access Journals (Sweden)

    Warouma Arifa

    2015-12-01

    Full Text Available Wear is the main reason for the loss of performance of the parts for agricultural machinery. It leads to the degradation of the soil working quality. This work aims to highlight the wear resistance of the harrows discs manufactured, consolidated and sharpened differently. The tests were conducted in the laboratory and the field of the Faculty of Exploitation and Repair of Agricultural Machinery of the State Technical University of Kirovograd (Ukraine in 2015. The technical equipment consists of devices for consolidation by electric discharge and for measurement the linear wear of discs, a harrow, a sand test bed, a tractor and discs made of different materials and technologies. Some parameterized were collected during the laboratory test each 5 ha and up to 20 ha of operation and in the fields each 30 ha until the time limit of exploitation. The Laboratory tests have shown that after twenty (20 ha of operation, the wear resistance of the experimental discs made of steel 65G and consolidated by electric discharge with simultaneous grinding (sharpening angle of 30° is 2.95 times higher than the discs in series made of steel 28MnB5. The field experiment gave the following results: According to agro technical requirements, the plowing depth limit of serial discs made of steel 28MnB5 was reached after an operating duration of 120 ha while for experimental discs made of steel 65G and consolidated by electric discharge with simultaneous grinding (sharpening angle of 30 degrees this duration is of 156 ha. The diameter wear limit of experimental discs was reached after an operating duration of 179 ha against 154 ha for the serial ones. Therefore, the new technology can be applied during the manufacture and / or the repair of the discs.

  2. Corrosion Characteristics of Welding Zones Welded with 1.25Cr-0.5 Mo Filler Metal to Forged Steel for Piston Crown Material

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jae-Hyun; Lee, Sung-Yul; Lee, Myeong-Hoon; Moon, Kyung-Man [Korea Maritime University, Dong Sam-Dong,Yong Do-ku, Busan (Korea, Republic of); Baek, Tae-Sil [Pohang College, Pohang (Korea, Republic of)

    2015-04-15

    A heavy oil of low quality has been mainly used in the diesel engine of the merchant ship as the oil price has been significantly jumped for several years. Thus, a combustion chamber of the engine has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas of the combustion chamber has been getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of the engine parts such as exhaust valve, piston crown and cylinder head surrounded with combustion chamber are more serious compared to the other parts of the engine. Therefore, an optimum repair welding for these engine parts is very important to prolong their lifetime in a economical point of view. In this study, 1.25Cr-0.5Mo filler metal was welded with SMAW method in the forged steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected and base metal zones were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% H{sub 2}SO{sub 4} solution. The weld metal and base metal zones exhibited the highest and lowest values of hardness respectively. And, the corrosion resistance of the heat affected and weld metal zones was also increased than that of the base metal zone. Furthermore, it appeared that the corrosive products with red color and local corrosion like as a pitting corrosion were more frequently observed on the surface of the base metal zone compared to the heat affected and weld metal zones. Consequently, it is suggested that the mechanical and corrosion characteristics of the piston crown can be predominantly improved by repair welding method using the 1.25Cr-0.5Mo electrode.

  3. Needs and challenges in precision wear measurement

    Energy Technology Data Exchange (ETDEWEB)

    Blau, P.J.

    1996-01-10

    Accurate, precise wear measurements are a key element in solving both current wear problems and in basic wear research. Applications range from assessing durability of micro-scale components to accurate screening of surface treatments and thin solid films. Need to distinguish small differences in wear tate presents formidable problems to those who are developing new materials and surface treatments. Methods for measuring wear in ASTM standard test methods are discussed. Errors in using alterate methods of wear measurement on the same test specimen are also described. Human judgemental factors are a concern in common methods for wear measurement, and an experiment involving measurement of a wear scar by ten different people is described. Precision in wear measurement is limited both by the capabilities of the measuring instruments and by the nonuniformity of the wear process. A method of measuring wear using nano-scale indentations is discussed. Current and future prospects for incorporating advanced, higher-precision wear measurement methods into standards are considered.

  4. Consideration of Wear Rates at High Velocities

    Science.gov (United States)

    2010-03-01

    tionally, the texts by Bayer [3; 4], Rabinowicz [30], and Stachowiak [32] thoroughly cover the topic of wear mechanisms. A summary of the material is...March 1976. 30. Rabinowicz , E. Friction and Wear of Metals. John Wiley & Sons, New York, 1995. 31. Saka, N., A. M. Eleiche, and N. P. Suh. “Wear of

  5. An Evaluation of High Velocity Wear

    Science.gov (United States)

    2007-03-01

    x10F~ -4 [18:18-19]. Authors such as Hutchings and Rabinowicz however, do not explicitly limit equation (12) to plastic wear. They suggest that...Surface Melting of Rotating Bands. Wear, Vol. 38, 235- 243 21. Rabinowicz , E. (1965). Friction and Wear of Materials (Second ed.). New York, NY

  6. Finite-temperature Casimir effect in piston geometry and its classical limit

    Energy Technology Data Exchange (ETDEWEB)

    Lim, S.C. [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor Darul Ehsan (Malaysia); Teo, L.P. [Multimedia University, Faculty of Information Technology, Cyberjaya, Selangor Darul Ehsan (Malaysia)

    2009-03-15

    We consider the Casimir force acting on a d-dimensional rectangular piston due to a massless scalar field with periodic, Dirichlet and Neumann boundary conditions and an electromagnetic field with perfect electric-conductor and perfect magnetic-conductor boundary conditions. The Casimir energy in a rectangular cavity is derived using the cut-off method. It is shown that the divergent part of the Casimir energy does not contribute to the Casimir force acting on the piston, thus renders an unambiguously defined Casimir force acting on the piston. At any temperature, it is found that the Casimir force acting on the piston increases from -{infinity} to 0 when the separation a between the piston and the opposite wall increases from 0 to {infinity}. This implies that the Casimir force is always an attractive force pulling the piston towards the closer wall, and the magnitude of the force gets larger as the separation a gets smaller. Explicit exact expressions for the Casimir force for small and large plate separations and for low and high temperatures are computed. The limits of the Casimir force acting on the piston when some pairs of transversal plates are large are also derived. An interesting result regarding the influence of temperature is that in contrast to the conventional result that the leading term of the Casimir force acting on a wall of a rectangular cavity at high temperature is the Stefan-Boltzmann (or black-body radiation) term which is of order T {sup d+1}, it is found that the contributions of this term from the two regions separating the piston cancel with each other in the case of piston. The high-temperature leading-order term of the Casimir force acting on the piston is of order T, which shows that the Casimir force has a nontrivial classical {Dirac_h}{yields}0 limit. Explicit formulas for the classical limit are computed. (orig.)

  7. Heat Treatment Effect on Microstructure, Hardness and Wear Resistance of Cr26 White Cast Iron

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shaoping; SHEN Yehui; ZHANG Hao; CHEN Dequan

    2015-01-01

    High chromium cast iron(HCCI) is taken as material of coal water slurry pump impeller, but it is susceptible to produce serious abrasive wear and erosion wear because of souring of hard coal particles. The research on optimization of heat treatments to improve abrasive wear properties of HCCI is insufficient, so effect of heat treatments on the microstructure, hardness, toughness, and wear resistance of Cr26 HCCI is investigated to determine the optimal heat treatment process for HCCI. A series of heat treatments are employed. The microstructures of HCCI specimens are examined by using optical microscopy and scanning electron microscopy. The hardness and impact fracture toughness of as-cast and heat treated specimens are measured. The wear tests are assessed by a Type M200 ring-on block wear tester. The results show the following: With increase of the quenching temperature from 950℃ to 1050℃, the hardness of Cr26 HCCI increased to a certain value, kept for a time and then decreased. The optimal heat treatment process is 2 h quenching treatment at 1000℃, followed by a subsequent 2 h tempering at 400℃. The hardness of HCCI is related to the precipitation and redissolution of secondary carbides in the process of heat treatment. The subsequent tempering treatment would result in a slight decrease of hardness but increase of toughness. The wear resistance is much related to the “supporting” effect of the matrix and the“protective” effect of the hard carbide embedded in the matrix, and the wear resistance is further dependent on the hardness and the toughness of the matrix. This research can provide an important insight on developing an optimized heat treatment method to improve the wear resistance of HCCI.

  8. Heat treatment effect on microstructure, hardness and wear resistance of Cr26 white cast iron

    Science.gov (United States)

    Zhou, Shaoping; Shen, Yehui; Zhang, Hao; Chen, Dequan

    2015-01-01

    High chromium cast iron(HCCI) is taken as material of coal water slurry pump impeller, but it is susceptible to produce serious abrasive wear and erosion wear because of souring of hard coal particles. The research on optimization of heat treatments to improve abrasive wear properties of HCCI is insufficient, so effect of heat treatments on the microstructure, hardness, toughness, and wear resistance of Cr26 HCCI is investigated to determine the optimal heat treatment process for HCCI. A series of heat treatments are employed. The microstructures of HCCI specimens are examined by using optical microscopy and scanning electron microscopy. The hardness and impact fracture toughness of as-cast and heat treated specimens are measured. The wear tests are assessed by a Type M200 ring-on block wear tester. The results show the following: With increase of the quenching temperature from 950 °C to 1050 °C, the hardness of Cr26 HCCI increased to a certain value, kept for a time and then decreased. The optimal heat treatment process is 2 h quenching treatment at 1000 °C, followed by a subsequent 2 h tempering at 400 °C. The hardness of HCCI is related to the precipitation and redissolution of secondary carbides in the process of heat treatment. The subsequent tempering treatment would result in a slight decrease of hardness but increase of toughness. The wear resistance is much related to the "supporting" effect of the matrix and the "protective" effect of the hard carbide embedded in the matrix, and the wear resistance is further dependent on the hardness and the toughness of the matrix. This research can provide an important insight on developing an optimized heat treatment method to improve the wear resistance of HCCI.

  9. Anti-wear and friction performance of ZrO2 nanoparticles as lubricant additive

    Institute of Scientific and Technical Information of China (English)

    Shiyu Ma; Shaohua Zheng; Duxia Cao; Hongna Guo

    2010-01-01

    The surface of ZrO2 nanoparticles was modified with silane coupling agent KH-560 by dispersing the nanoparticles in 20# machine oil.The tribological performance of the 20# machine oil with ZrO2 nanoparticles was evaluated by a four-ball tester and a thrust-ring machine.The loss of the thrust-ring weight was measured by an electronic balance with a precision of 0.0001 g.The worn surface was examined under a metallographic microscope with 400-times magnification.The results showed that the average friction coefficient decreased by 27.34%,and that the weight loss of the thrust-ring indicated no wear or nega-tive wear,the wear loss after six loads tests being-0.0163 g.The anti-wear(AW)and reducing friction(RF)abilities of the oil with ZrO2 nanoparticles addition were considerably improved,maximizing at an additive concentration of 0.5 wt%.

  10. Free-piston engine-and-hydraulic pump for railway vehicles

    Directory of Open Access Journals (Sweden)

    A. F. Golovchuk

    2013-04-01

    Full Text Available Purpose. The development of the free-piston diesel engine-and-hydraulic pump for the continuously variable hydrostatical transmission of mobile power vehicles. Methodology. For a long time engine builders have been interesting in the problem of developing free piston engines, which have much bigger coefficient of efficiency (40…80%. Such engines don’t have the conversion of reciprocating motion for inner combustion engine piston into rotating motion of crankshaft, from which the engine torque is transferred to the power machine transmission. Free-piston engines of inner combustion don’t have the crank mechanism (CM that significantly reduces mechanical losses for friction. Such engines can be used as compressors. Free-piston engine compressor (FPEC – is a free-piston machine in which energy received from engine’s cylinder is being transferred direct to compressor’s pistons connected with operational pistons of engine without crank mechanism. Part of the pressed air is being consumed for engine cylinder drain and the other part is going to the consumer. Findings. The use of free-piston engines-and-hydraulic pumps as power-transmission plants of power vehicles (diesel locomotives, combine harvester, tractors, cars and other mobile and stationary power installations with the continuously variable transmissions allows cost effectiveness improvement and metal consumption reduction of these vehicles, since the cost effectiveness of FPE is higher by 25-30%, and the metal consumption is lower by 40-50%. Originality. One of the important advantages of the free-piston engines is their simplicity and engine balance. As a result of the crank mechanism absence their construction is much simplified and the vibrations, peculiar to the ordinary engines are eliminated. In such installation the engine pistons are directly connected through the rod to compressor pistons and therefore there are no losses in the bearing bushes. Practical value. The free-piston

  11. Sliding wear resistance of iron aluminides

    Indian Academy of Sciences (India)

    Garima Sharma; M Sundararaman; N Prabhu; G L Goswami

    2003-04-01

    Room temperature dry sliding wear behaviour of iron aluminides containing 28% aluminium and various amounts of chromium has been investigated using pin on disk wear tester. The aluminides were heat treated to have ordered 3 structure. It was found that wear rate of the aluminides increased with the increase of applied normal load and sliding speed. Wear resistance of the aluminides increased with increase in chromium content. SEM observation of the worn surface showed that the microcutting and microploughing were the dominant sliding wear mechanisms.

  12. Heat transfer analysis of liquid piston compressor for hydrogen applications

    DEFF Research Database (Denmark)

    Kermani, Nasrin Arjomand; Rokni, Masoud

    2015-01-01

    based on the mass and energy balance of the hydrogen, liquid, and the wall of the compression chamber at each time step and positional node with various compression ratios, to calculate the temperature distribution of the system. The amount of heat extracted from hydrogen, directly at the interface......A hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model is developed...... at the interface. Moreover, the results of the sensitivity analysis illustrates that increasing the total heat transfer coefficients at the interface and the wall, together with compression time, play key roles in reducing the hydrogen temperature. Increasing the total heat transfer coefficient at the interface...

  13. Integrated two-cylinder liquid piston Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd, E-mail: todd.sulchek@me.gatech.edu [George W. Woodruff School of Mechanical Engineering and Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2014-10-06

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  14. Heat transfer analysis of liquid piston compressor for hydrogen applications

    DEFF Research Database (Denmark)

    Kermani, Nasrin Arjomand; Rokni, Masoud

    2015-01-01

    at the interface. Moreover, the results of the sensitivity analysis illustrates that increasing the total heat transfer coefficients at the interface and the wall, together with compression time, play key roles in reducing the hydrogen temperature. Increasing the total heat transfer coefficient at the interface......A hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model is developed...... and through the walls, is investigated and compared with the adiabatic case. The results show that depending on heat transfer correlation, the hydrogen temperature reduces slightly between 0.2% and 0.4% compared to the adiabatic case, at 500bar, due to the large wall resistance and small contact area...

  15. Heat Analysis of Liquid piston Compressor for Hydrogen Applications

    DEFF Research Database (Denmark)

    Kermani, Nasrin Arjomand; Rokni, Masoud

    2014-01-01

    of hydrogen temperature from adiabatic case is very small, due to large wall resistance and small contact area at the interface. Moreover, the results illustrates that the increasing of the total heat transfer coefficient at the interface and the wall will play a key role in reducing the hydrogen temperature......A new hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model...... and through the walls, is investigated and compared with the adiabatic case. The amount of heat transfer towards the wall is assessed according to widely used heat transfer models available in the literature.The results show very low sensitivity of the model to different heat transfer correlations. Deviation...

  16. Integrated two-cylinder liquid piston Stirling engine

    Science.gov (United States)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd

    2014-10-01

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  17. Layered clustering multi-fault diagnosis for hydraulic piston pump

    Science.gov (United States)

    Du, Jun; Wang, Shaoping; Zhang, Haiyan

    2013-04-01

    Efficient diagnosis is very important for improving reliability and performance of aircraft hydraulic piston pump, and it is one of the key technologies in prognostic and health management system. In practice, due to harsh working environment and heavy working loads, multiple faults of an aircraft hydraulic pump may occur simultaneously after long time operations. However, most existing diagnosis methods can only distinguish pump faults that occur individually. Therefore, new method needs to be developed to realize effective diagnosis of simultaneous multiple faults on aircraft hydraulic pump. In this paper, a new method based on the layered clustering algorithm is proposed to diagnose multiple faults of an aircraft hydraulic pump that occur simultaneously. The intensive failure mechanism analyses of the five main types of faults are carried out, and based on these analyses the optimal combination and layout of diagnostic sensors is attained. The three layered diagnosis reasoning engine is designed according to the faults' risk priority number and the characteristics of different fault feature extraction methods. The most serious failures are first distinguished with the individual signal processing. To the desultory faults, i.e., swash plate eccentricity and incremental clearance increases between piston and slipper, the clustering diagnosis algorithm based on the statistical average relative power difference (ARPD) is proposed. By effectively enhancing the fault features of these two faults, the ARPDs calculated from vibration signals are employed to complete the hypothesis testing. The ARPDs of the different faults follow different probability distributions. Compared with the classical fast Fourier transform-based spectrum diagnosis method, the experimental results demonstrate that the proposed algorithm can diagnose the multiple faults, which occur synchronously, with higher precision and reliability.

  18. CFD analysis of a diaphragm free-piston Stirling cryocooler

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-10-01

    This paper presents a Computational Fluid Dynamics (CFD) analysis of a novel free-piston Stirling cryocooler that uses a pair of metal diaphragms to seal and suspend the displacer. The diaphragms allow the displacer to move without rubbing or moving seals. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicated the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. The diaphragm's large diameter and short stroke produces a significant radial component to the oscillating flow fields inside the cryocooler which were not modelled in the one-dimensional analysis tool Sage that was used to design the prototypes. Compared with standard pistons, the diaphragm geometry increases the gas-to-wall heat transfer due to the higher velocities and smaller hydraulic diameters. A Computational Fluid Dynamics (CFD) model of the cryocooler was constructed to understand the underlying fluid-dynamics and heat transfer mechanisms with the aim of further improving performance. The CFD modelling of the heat transfer in the radial flow fields created by the diaphragms shows the possibility of utilizing the flat geometry for heat transfer, reducing the need for, and the size of, expensive heat exchangers. This paper presents details of a CFD analysis used to model the flow and gas-to-wall heat transfer inside the second prototype cryocooler, including experimental validation of the CFD to produce a robust analysis.

  19. Using IR Imaging of Water Surfaces for Estimating Piston Velocities

    Science.gov (United States)

    Gålfalk, M.; Bastviken, D.; Arneborg, L.

    2013-12-01

    The transport of gasses dissolved in surface waters across the water-atmosphere interface is controlled by the piston velocity (k). This coefficient has large implications for, e.g., greenhouse gas fluxes but is challenging to quantify in situ. At present, empirical k-wind speed relationships from a small number of studies and systems are often extrapolated without knowledge of model performance. It is therefore of interest to search for new methods for estimating k, and to compare the pros and cons of existing and new methods. Wind speeds in such models are often measured at a height of 10 meters. In smaller bodies of water such as lakes, wind speeds can vary dramatically across the surface through varying degrees of wind shadow from e.g. trees at the shoreline. More local measurements of the water surface, through wave heights or surface motion mapping, could give improved k-estimates over a surface, also taking into account wind fetch. At thermal infrared (IR) wavelengths water has very low reflectivity (depending on viewing angle) than can go below 1%, meaning that more than 99% is heat radiation giving a direct measurement of surface temperature variations. Using an IR camera at about 100 frames/s one could map surface temperature structures at a fraction of a mm depth even with waves present. In this presentation I will focus on IR imaging as a possible tool for estimating piston velocities. Results will be presented from IR field measurements, relating the motions of surface temperature structures to k calculated from other simultaneous measurements (flux chamber and ADV-Based Dissipation Rate), but also attempting to calculate k directly from the IR surface divergence. A relation between wave height and k will also be presented.

  20. 5-kWe Free-piston Stirling Engine Convertor

    Science.gov (United States)

    Chapman, Peter A.; Vitale, Nicholas A.; Walter, Thomas J.

    2008-01-01

    The high reliability, long life, and efficient operation of Free-Piston Stirling Engines (FPSEs) make them an attractive power system to meet future space power requirements with less mass, better efficiency, and less total heat exchanger area than other power convertor options. FPSEs are also flexible in configuration as they can be coupled with many potential heat sources and various heat input systems, heat rejection systems, and power management and distribution systems. Development of a 5-kWe Stirling Convertor Assembly (SCA) is underway to demonstrate the viability of an FPSE for space power. The design is a scaled-down version of the successful 12.5-kWe Component Test Power Converter (CTPC) developed under NAS3-25463. The ultimate efficiency target is 25% overall convertor efficiency (electrical power out over heat in). For the single cylinder prototype now in development, cost and time constraints required use of economical and readily available materials (steel versus beryllium) and components (a commercially available linear alternator) and thus lower efficiency. The working gas is helium at 150 bar mean pressure. The design consists of a displacer suspended on internally pumped gas bearings and a power piston/alternator supported on flexures. Non-contacting clearance seals are used between internal volumes. Heat to and from the prototype convertor is done via pumped liquid loops passing through shell and tube heat exchangers. The preliminary and detail designs of the convertor, controller, and support systems (heating loop, cooling loop, and helium supply system) are complete and all hardware is on order. Assembly and test of the prototype at Foster- Miller is planned for early 2008, when work will focus on characterizing convertor dynamics and steady-state operation to determine maximum power output and system efficiency. The device will then be delivered to Auburn University where assessments will include start-up and shutdown characterization and

  1. Accomplishments in free-piston stirling tests at NASA GRC

    Science.gov (United States)

    Schreiber, Jeffrey G.; Skupinski, Robert C.

    2002-01-01

    A power system based on the Stirling Radioisotope Generator (SRG) has been identified for potential use on deep space missions, as well as for Mars rovers that may benefit from extended operation. The Department of Energy (DOE) has responsibility for developing the generator and the NASA Glenn Research Center (GRC) is supporting DOE in this effort. The generator is based on a free-piston Stirling power convertor that has been developed by the Stirling Technology Company (STC) under contract to DOE. The generator would be used as a high-efficiency alternative to the Radioisotope Thermoelectric Generators (RTGs) that have been used on many previous missions. The increased efficiency leads to a factor of 3 to 4 reduction in the inventory of plutonium required to heat the generator. GRC has been involved in the development of Stirling power conversion technology for over 25 years. The support provided to this project by GRC has many facets and draws upon the lab's scientists and engineers that have gained experience in applying their skills to the previous Stirling projects. This has created a staff with an understanding of the subtleties involved in applying their expertise to Stirling systems. Areas include materials, structures, tribology, controls, electromagnetic interference, permanent magnets, alternator analysis, structural dynamics, and cycle performance. One of the key areas of support to the project is in the performance testing of the free-piston Stirling convertors. Since these power convertors are the smallest, lowest power Stirling machines that have been tested at GRC, a new laboratory was equipped for this project. Procedures and test plans have been created, instrumentation and data systems developed, and Stirling convertors have been tested. This paper will describe the GRC test facility, the test procedures that are used, present some of the test results and outline plans for the future. .

  2. Wear prediction in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, E.J. [USDOE Morgantown Energy Technology Center, WV (United States); Rogers, W.A. [EG and G Washington Analytical Services Center, Inc., Morgantown, WV (United States)

    1993-06-01

    A procedure to model the wear of surfaces exposed to a fluidized bed is formulated. A stochastic methodology adapting the kinetic theory of gases to granular flows is used to develop an impact wear model. This uses a single-particle wear model to account for impact wear from all possible-particle collisions. An adaptation of a single-particle abrasion model to describe the effects of many abrading particles is used to account for abrasive wear. Parameters describing granular flow within the fluidized bed, necessary for evaluation of the wear expressions, are determined by numerical solution of the fluidized bed hydrodynamic equations. Additional parameters, describing the contact between fluidized particles and the wearing surface, are determined by optimization based on wear measurements. The modeling procedure was used to analyze several bubbling and turbulent fluidized bed experiments with single-tube and tube bundle configurations. Quantitative agreement between the measured and predicted wear rates was found, with some exceptions for local wear predictions. This work demonstrates a methodology for wear predictions in fluidized beds.

  3. Fluoridation and tooth wear in Irish adults.

    LENUS (Irish Health Repository)

    Burke, F M

    2010-10-01

    The aim of this study was to determine the prevalence of tooth wear in adults in Ireland and its relationship with water fluoridation. The National Survey of Adult Oral Health was conducted in 2000\\/2001. Tooth wear was determined using a partial mouth examination assessing the upper and lower anterior teeth. A total of 2456 subjects were examined. In this survey, increasing levels and severity of tooth wear were associated with ageing. Men were more affected by tooth wear and were more likely to be affected by severe tooth wear than women. It was found that age, and gender were significant predictors of tooth wear (P < 0.01). Overall, there was no significant relationship between fluoridation and tooth wear in this study.

  4. Prime rings with PI rings of constants

    CERN Document Server

    Kharchenko, V K; Rodríguez-Romo, S

    1996-01-01

    It is shown that if the ring of constants of a restricted differential Lie algebra with a quasi-Frobenius inner part satisfies a polynomial identity (PI) then the original prime ring has a generalized polynomial identitiy (GPI). If additionally the ring of constants is semiprime then the original ring is PI. The case of a non-quasi-Frobenius inner part is also considered.

  5. Evaluation of wear rate on material vane of hydraulic pump by standard ASTM G 77

    OpenAIRE

    Rodriguez Ballesteros, Nairo Julian

    2015-01-01

    En el desarrollo de la investigación se evaluó la rata de desgaste en los materiales (bronce C93700 y resina fenólica reforzada con fibras de Aramida) de las paletas de una bomba hidráulica de referencia BLACKMER ML, bajo el método estándar ASTM G77- 2010, “Ranking Resistence of Materials to Sliding Wear Using Block-on-Ring Wear Test”. A partir de un análisis experimental del contacto par tribológico probetas “block on ring” bajo cinco niveles de carga (5, 10, 15, 20 y 25 N), s...

  6. Wear of micro end mills

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2005-01-01

    This paper addresses the important issue of wear on micro end mills considering relevant metrological tools for its characterization and quantification. Investigation of wear on micro end mills is particularly difficult and no data are available in the literature. Small worn volumes cause large...... deviations from the ideal micro tool shape, dramatically changing the cutting edge profile as well as rake and clearance angles. This critically affects the performance of the micro tool leading to increased cutting forces and micro tool deflections with detrimental effects on the accuracy of the machined...... part. For this investigation 200 microns end mills are considered. Visual inspection of the micro tools requires high magnification and depth of focus. 3D reconstruction based on scanning electron microscope (SEM) images and stereo-pair technique is foreseen as a possible method for quantification...

  7. Open Loop Heat Pipe Radiator Having a Free-Piston for Wiping Condensed Working Fluid

    Science.gov (United States)

    Weinstein, Leonard M. (Inventor)

    2015-01-01

    An open loop heat pipe radiator comprises a radiator tube and a free-piston. The radiator tube has a first end, a second end, and a tube wall, and the tube wall has an inner surface and an outer surface. The free-piston is enclosed within the radiator tube and is capable of movement within the radiator tube between the first and second ends. The free-piston defines a first space between the free-piston, the first end, and the tube wall, and further defines a second space between the free-piston, the second end, and the tube wall. A gaseous-state working fluid, which was evaporated to remove waste heat, alternately enters the first and second spaces, and the free-piston wipes condensed working fluid from the inner surface of the tube wall as the free-piston alternately moves between the first and second ends. The condensed working fluid is then pumped back to the heat source.

  8. Performance analysis of a biodiesel fuelled diesel engine with the effect of alumina coated piston

    Directory of Open Access Journals (Sweden)

    Senthil Kumar Srinivasan

    2017-01-01

    Full Text Available Biodiesel is one of the best alternative fuels to Diesel engine among other sources due to having potential to reduce emissions. Biodiesel is a renewable, biodegradable and environment friendly fuel in nature. The advantages of biodiesel are lower exhaust gas emissions and its biodegradability and renewability compared with petroleum-based diesel fuel. The energy of the biodiesel can be released more efficiently with the concept of semi adiabatic (thermal barrier coated piston engine. The objective of this study is to investigate the performance and emission characteristics of a single cylinder direct injection Diesel engine using 25% biodiesel blend (rubber seed oil methyl ester as fuel with thermal barrier coated piston. Initially the piston crown was coated with alumina (Al2O3 of thickness of 300 micron (0.3 mm by plasma coating method. The results revealed that the brake thermal efficiency was increased by 4% and brake specific fuel consumption was decreased by 9% for B25 with coated piston compared to un-coated piston with diesel. The smoke, CO, and HC emissions were also decreased for B25 blend with coated piston compared with the uncoated piton engine. The combustion characteristics such as peak pressure, maximum rate of pressure rise, and heat release rate were increased and the ignition delay was decreased for B25 blend for the coated piston compared with diesel fuel.

  9. Hydraulic System Wear Debris Analysis.

    Science.gov (United States)

    1982-08-03

    drawn. Each one-=L sample was drawn with a clean plastic pipette of one-mL capacity. The samples were placed in clean Ferrogram preparation bottles ...and from cavities in a block which held linear seals into sampling bottles . Several photographs of this debris , which was deposited on Ferro- grams...silicon in the glass overshadowed the elements of the wear debris . To overcome this difficulty, the Ferrogram should be pre- pared on a carbon-filled

  10. Development of Cone Wedge Ring Expansion Test to Evaluate Mechanical Properties of Clad Tubing Structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-01

    To determine the hoop tensile properties of irradiated fuel cladding in a hot cell, a cone wedge ring expansion test method was developed. A four-piece wedge insert was designed with tapered angles matched to the cone shape of a loading piston. The ring specimen was expanded in the radial direction by the lateral expansion of the wedges under the downward movement of the piston. The advantages of the proposed method are that implementation of the test setup in a hot cell is simple and easy, and that it enables a direct strain measurement of the test specimen from the piston’s vertical displacement soon after the wedge-clad contact resistance is initiated.

  11. On the identification of piston slap events in internal combustion engines using tribodynamic analysis

    Science.gov (United States)

    Dolatabadi, N.; Theodossiades, S.; Rothberg, S. J.

    2015-06-01

    Piston slap is a major source of vibration and noise in internal combustion engines. Therefore, better understanding of the conditions favouring piston slap can be beneficial for the reduction of engine Noise, Vibration and Harshness (NVH). Past research has attempted to determine the exact position of piston slap events during the engine cycle and correlate them to the engine block vibration response. Validated numerical/analytical models of the piston assembly can be very useful towards this aim, since extracting the relevant information from experimental measurements can be a tedious and complicated process. In the present work, a coupled simulation of piston dynamics and engine tribology (tribodynamics) has been performed using quasi-static and transient numerical codes. Thus, the inertia and reaction forces developed in the piston are calculated. The occurrence of piston slap events in the engine cycle is monitored by introducing six alternative concepts: (i) the quasi-static lateral force, (ii) the transient lateral force, (iii) the minimum film thickness occurrence, (iv) the maximum energy transfer, (v) the lubricant squeeze velocity and (vi) the piston-impact angular duration. The validation of the proposed methods is achieved using experimental measurements taken from a single cylinder petrol engine in laboratory conditions. The surface acceleration of the engine block is measured at the thrust- and anti-thrust side locations. The correlation between the theoretically predicted events and the measured acceleration signals has been satisfactory in determining piston slap incidents, using the aforementioned concepts. The results also exhibit good repeatability throughout the set of measurements obtained in terms of the number of events occurring and their locations during the engine cycle.

  12. Radical theory of rings

    CERN Document Server

    Gardner, JW

    2003-01-01

    Radical Theory of Rings distills the most noteworthy present-day theoretical topics, gives a unified account of the classical structure theorems for rings, and deepens understanding of key aspects of ring theory via ring and radical constructions. Assimilating radical theory's evolution in the decades since the last major work on rings and radicals was published, the authors deal with some distinctive features of the radical theory of nonassociative rings, associative rings with involution, and near-rings. Written in clear algebraic terms by globally acknowledged authorities, the presentation

  13. Research on Measurements for Temperature and Stress of Pistons in Internal Combustion Engine

    Institute of Scientific and Technical Information of China (English)

    DONG Xiao-rui; TAN Jian-song

    2008-01-01

    In both numerical simulation and experimental research for the piston of internal combustion engine, the verification foundations are always insufficient. The reason is the measurements for its transient temperature and stress under actual operation conditions are very difficult. A multi-channel measurement-storage technology is used in the engine bench experiment to measure the piston temperature and stress in real time. The temperature and stress changes in the engine operation process are obtained. They provide reliable instructive criteria for numerical analysis and experiment of the piston working state.

  14. Acoustic radiation field of the truncated parametric source generated by a piston radiator model and experiment

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiaoliang; ZHU Zhemin; DU Gonghuan; TANG Haiqing; LI Shui; MIAO Rongxing

    2001-01-01

    A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filter can be viewed as a cylindrical source within the Rayleigh distance of the piston. When the radius of the piston is much smaller than the length of the parametric region, this model is reduced to the Berketey's End-Fire Line Array model. Comparison between numerical calculations and experimental measurement show that the generated parametric sound field (especially near the axis) agrees well with the experiment results.

  15. Design of wireless temperature measurement system for piston based on CC2530

    Science.gov (United States)

    Rongyu, Ge; Jin, Wang; Yimin, Wu; Guodong, Wu

    2016-11-01

    Temperature measurement of piston is important to analysis its temperature field. Since it is difficult to extract the temperature signal in the piston by hard line, a multi-channel wireless measurement system of piston temperature is developed. The wireless SOC CC2530 is used. NTC thermistors with glass package are selected as temperature sensors. The realization of hardware and the design of software flowchart are explained in detail. The actual test demonstrates that the system has high measurement accuracy and strong practical value.

  16. Theoretical study of flow ripple for an aviation axial-piston pump with damping holes in the valve plate

    Institute of Scientific and Technical Information of China (English)

    Guan Changbin; Jiao Zongxia; He Shouzhan

    2014-01-01

    Based on the structure of a certain type of aviation axial-piston pump’s valve plate which adopts a pre-pressurization fluid path (consisting a damping hole, a buffer chamber, and an orifice) to reduce flow ripple, a single-piston model of the aviation axial-piston pump is presented. This sin-gle-piston model comprehensively considers fluid compressibility, orifice restriction effect, fluid resistance in the capillary tube, and the leakage flow. Besides, the instantaneous discharge areas used in the single-piston model have been calculated in detail. Based on the single-piston model, a multi-piston pump model has been established according to the simple hydraulic circuit. The sin-gle-and multi-piston pump models have been realized by the S-function in Matlab/Simulink. The developed multi-piston pump model has been validated by being compared with the numerical result by computational fluid dynamic (CFD). The effects of the pre-pressurization fluid path on the flow ripple and the instantaneous pressure in the piston chamber have been studied and opti-mized design recommendations for the aviation axial-piston pump have been given out.

  17. On the wall jet from the ring crevice of an internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Cloutman, L.D. [Lawrence Livermore National Lab., CA (United States); Green, R.M. [Sandia National Labs., Livermore, CA (United States)

    1996-05-01

    Numerical simulations and experiments of the jetting of gases from the ring crevices of a laboratory engine shortly after exhaust valve opening showed an unanticipated radial flow of the crevice gases into the main combustion chamber. We report well-resolved numerical simulations of a wall jet that show that this radial motion is driven by vorticity generation in the wall boundary layer and at the corner of the piston crown.

  18. 数字式气体活塞压力计的活塞系统设计%Piston-Cylinder Assembly Design of the Digital Piston Pressure Gauge

    Institute of Scientific and Technical Information of China (English)

    王丽; 盛晓岩

    2012-01-01

    The piston-cylinder assembly design method of digital piston pressure gauge is introduced. The design principle, material selection and design of critical dimension are introduced in detail. The result is certified by the performance index of the piston-cylinder assembly and digital piston pressure gauge. Theoretical basis is provided for the rapid development of digital piston pressure gauge.%介绍了数字式气体活塞压力计的关键部件——活塞系统的设计方法,详细阐述了活塞系统的设计原则、材料的选择以及关键尺寸的设计,并通过了活塞系统性能指标和数字式活塞压力计性能指标的验证,为数字式活塞压力计技术的迅速发展提供了理论依据.

  19. Advance and Status on NDT Research of Pistons in High-Power Engines%大马力发动机活塞无损检测研究现状与进展

    Institute of Scientific and Technical Information of China (English)

    倪培君

    2011-01-01

    回顾了大马力发动机活塞发展历程及无损检测技术的应用情况。介绍了先进的电子束焊接活塞无损检测方法,包括活塞顶的超声波五探头水浸检测、活塞顶和活塞体的射线实时成像检测、电子束焊缝的超声波六探头水浸检测及工业CT检测、镶圈粘接质量的超声波检测等。论述了多种无损检测方法综合应用在电子束焊接活塞质量保证中的重要作用。最后对新型颗粒增强铝基复合材料活塞的无损检测技术作了展望。%A review of the investigations that were made on the development and application of the NDT( Nondestructive testing) technique for pistons of high-power engines was presented. The NDT technologies used in advanced EBW( Electron Beam Welding) pistons were also recommended, including ultrasonic immersion testing for piston head with five probes, X-ray real-time imaging for heads and bodies, ultrasonic immersion testing with six probes as well as industrial X-ray computed tomography for electron beam welds, ultrasonic immersion testing for the bonding quality of ring carrier, etc. The important role of several NDT technologies comprehensively applied to quality con.trois of EBW pistons was discussed. Finally, the future research trends of the NDT technologies for the latest piston of particulates reinforced Al matrix composites were outlined.

  20. A new methodology for predictive tool wear

    Science.gov (United States)

    Kim, Won-Sik

    An empirical approach to tool wear, which requires a series of machining tests for each combination of insert and work material, has been a standard practice for industries since early part of the twentieth century. With many varieties of inserts and work materials available for machining, the empirical approach is too experiment-intensive that the demand for the development of a model-based approach is increasing. With a model-based approach, the developed wear equation can be extended without additional machining experiments. The main idea is that the temperatures on the primary wear areas are increasing such that the physical properties of the tool material degrade substantially and consequently tool wear increases. Dissolution and abrasion are identified to be the main mechanisms for tool wear. Flank wear is predominantly a phenomenon of abrasion as evident by the presence of a scoring mark on the flank surface. Based on this statement, it is reasonable to expect that the flank-wear rate would increase with the content of hard inclusions. However, experimental flank wear results did not necessary correspond to the content of cementite phase present in the steels. Hence, other phenomena are believed to significantly affect wear behavior under certain conditions. When the cutting temperature in the flank interface is subjected to high enough temperatures, pearlitic structure austenizes. During the formation of a new austenitic phase, the existing carbon is dissolved into the ferrite matrix, which will reduce the abrasive action. To verify the austenitic transformation, turning tests were conducted with plain carbon steels. The machined surface areas are imaged using X-ray diffraction the Scanning Electron Microscope (SEM) and the Transmission Electron Microscope (TEM). On the other hand, crater wear occurs as a result of dissolution wear and abrasive wear. To verify the wear mechanisms of crater wear, various coating inserts as well as uncoated inserts were

  1. Birth Control Ring

    Science.gov (United States)

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Birth Control Ring KidsHealth > For Teens > Birth Control Ring A A A What's in this article? ... español Anillo vaginal anticonceptivo What Is It? The birth control ring is a soft, flexible, doughnut-shaped ring ...

  2. 1987 overview of free-piston Stirling technology for space power application

    Science.gov (United States)

    Slaby, Jack G.; Alger, Donald L.

    1987-01-01

    The Lewis Research Center program concerned with the development of a free-piston Stirling engine for space-power applications is examined. The system mass of a Stirling system is compared to that of a Brayton system for the same peak temperature and output power; the advantages of the Stirling system are discussed. The predicted and experimental performances of the 25 kWe opposed-piston space power demonstrator engine are evaluated. It is determined that in order to enhance performance the regenerator needs to be modified, and the gas bearing flow between the displacer and power piston needs to be isolated in order to increase the operating stroke. Identification and correction of the energy losses, the design and operation of the linear alternator, and heat exchange concepts are considered. The design parameters and conceptual design characteristics for a 25 kWe single-cylinder free-piston Stirling space-power converter are described.

  3. High Specific Power Multiple-Cylinder Alpha Free-Piston Stirling Engine Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort will result in a design of a 30 kWe dual opposed alpha free-piston Stirling engine power conversion system for space applications, and provide...

  4. Investigations of high-frequency induction hardening process for piston rod of shock absorber

    Institute of Scientific and Technical Information of China (English)

    Xianhua Cheng; Qianqian Shangguan

    2005-01-01

    The microhardness of piston rods treated with different induction hardening processes was tested. The experimental results reveal that the depth of the hardened zone is proportional to the ratio of the moving speed of the piston rod to the output power of the induction generator. This result is proved correct through the Finite Element Method (FEM) simulation of the thermal field of induction heating. From tensile and impact tests, an optimized high frequency induction hardening process for piston rods has been obtained, where the output power was 82%×80 kW and the moving speed of workpiece was 5364 mm/min. The piston rods, treated by the optimized high frequency induction hardening process, show the best comprehensive mechanical performance.

  5. Design and theoretical analysis of a sliding valve distribution radial piston pump

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Guo; Shengdun, Zhao; Yanghuiwen, Yu [Xian Jiaotong University, Xian (China); Peng, Shang [Xian Engineering University of Armed Police Force, Xian (China)

    2016-01-15

    A Sliding valve distribution radial piston pump (SVDRPP) is presented. In this pump, a new distribution method that uses sliding valves to distribute oil for the piston chambers is developed. With this design, the disadvantages brought by the distribution shaft and the check valves (traditional distribution mechanisms), such as the poor stress state of the shaft and the energy waste for opening the check valves, are expected to be eliminated. In addition, a method of using pressure oil to accomplish the returning stroke of the piston is also proposed, which could be used to replace the usage of springs along with their shortcomings. A pump with five pistons is designed as an example to elaborate the structure and the working principle of SVDRPP. Furthermore, the flow characteristics of SVDRPP are studied, and the formulas of the displacement, the average flow rate and the instantaneous flow rate are deduced.

  6. A thermodynamic study for the optimization of stable operation of free piston Stirling engines

    Energy Technology Data Exchange (ETDEWEB)

    Rogdakis, E.D.; Bormpilas, N.A.; Koniakos, I.K. [National Technical Univerisity, Athens (Greece). Dept. of Mechanical Engineering

    2004-03-01

    One of the most novel applications of the Stirling cycle is in the free piston configuration that was initially designed by W. Beale. In free piston Stirling engines (FPSEs), there are no mechanical linkages coupling the pistons or displacers, the motions of the reciprocating components follow the working gas pressure variations. Fillipo de Monte and G. Benvenuto have recently proposed a linearization technique of the dynamic balance equations. The aim of this paper is to predict the thermodynamic conditions for stable operation of FPSEs and their modeling. The equations of the angular velocity are solved analytically in terms of the working gas mass and the displacer-piston phase angle of the machine. Using the criterion of stable engine cyclic steady operation, a mathematically rigorous form is obtained for the main parameters of the engine. Furthermore, for simplicity reasons, thermodynamic magnitudes are obtained using the Schmidt analysis (isothermal model). (author)

  7. Adaptive individual-cylinder thermal state control using piston cooling for a GDCI engine

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Gregory T; Husted, Harry L; Sellnau, Mark C

    2015-04-07

    A system for a multi-cylinder compression ignition engine includes a plurality of nozzles, at least one nozzle per cylinder, with each nozzle configured to spray oil onto the bottom side of a piston of the engine to cool that piston. Independent control of the oil spray from the nozzles is provided on a cylinder-by-cylinder basis. A combustion parameter is determined for combustion in each cylinder of the engine, and control of the oil spray onto the piston in that cylinder is based on the value of the combustion parameter for combustion in that cylinder. A method for influencing combustion in a multi-cylinder engine, including determining a combustion parameter for combustion taking place in in a cylinder of the engine and controlling an oil spray targeted onto the bottom of a piston disposed in that cylinder is also presented.

  8. Actin Rings of Power.

    Science.gov (United States)

    Schwayer, Cornelia; Sikora, Mateusz; Slováková, Jana; Kardos, Roland; Heisenberg, Carl-Philipp

    2016-06-20

    Circular or ring-like actin structures play important roles in various developmental and physiological processes. Commonly, these rings are composed of actin filaments and myosin motors (actomyosin) that, upon activation, trigger ring constriction. Actomyosin ring constriction, in turn, has been implicated in key cellular processes ranging from cytokinesis to wound closure. Non-constricting actin ring-like structures also form at cell-cell contacts, where they exert a stabilizing function. Here, we review recent studies on the formation and function of actin ring-like structures in various morphogenetic processes, shedding light on how those different rings have been adapted to fulfill their specific roles.

  9. Alternative loop rings

    CERN Document Server

    Goodaire, EG; Polcino Milies, C

    1996-01-01

    For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

  10. Long-duration life tests of slip ring capsule assemblies for inertial guidance platforms

    Science.gov (United States)

    Cole, S. R.; Glossbrenner, E. W.

    1974-01-01

    Eight slip ring capsules, each having 80 or 100 circuits, were operated for time periods ranging from 14,300 hours to 24,700 hours. The test mode simulated the motion of gimbal axes of the Saturn inertial guidance the platform in an organic free nitrogen environment. Computer-compiled noise data (approximately 45,000 recordings) were graphed as a function of test time and position within the capsules and as extreme probability distributions. Greater than ninety-nine percent of the noise measurements for the capsules with sufficient lubrication were less than 10 milliohms. Capsules with glass dielectrics did not perform significantly differently than those with filled epoxy dielectrics. The initial wear mode of prow formation was followed by rider wear. After 10 to the 8th power wipes, ring wear depth did not exceed the surface finish and the radial rider wear depth was less than 13 microns.

  11. Surface Wear Measurement Using Optical Correlation Technique

    Science.gov (United States)

    Acinger, Kresimir

    1983-12-01

    The coherent optical correlation technique was applied for measuring the surface wear of a tappet (part of car engine), worn by friction with the camshaft. It was found that maximum correlation intensity decays exponentially with the number of wear cycles (i.e. camshaft revolutions). Tappets of the same make have an identical rate of correlation decay. Tappets of different makes have different rates of correlation decay which are in agreement with observed long term wear.

  12. The thermodynamic equilibrium of gas in a box divided by a piston

    CERN Document Server

    Herrera-Gomez, Alberto

    2010-01-01

    The equilibrium conditions of a system consisting of a box with gas divided by a piston are revised. The apparent indetermination of the problem is solved by explicitly imposing the constancy of the internal energy when the Entropy Maximum Principle is applied. The equality of the pressures is naturally concluded from this principle when the piston is allowed to spontaneously move. The application of the Energy Minimum Principle is also revised.

  13. Performance analysis of a 2-stroke micro free-piston swing engine

    Institute of Scientific and Technical Information of China (English)

    Zhang Shimin; Guo Zhiping; Wang Jinsong

    2009-01-01

    The micro free-piston swing engine (MFPSE) is a new structure, free-piston internal combustion engine. The dynamic model integrated MFPSE with a power generator and thermodynamic models in compression, power and scavenge processes based on the open thermodynamic systems were presented. A simulation was executed at given geometric parameters and initial conditions. The results manifest that the working principle of MFPSE is feasible.

  14. An investigation of the fluid-structure interaction of piston/cylinder interface

    Science.gov (United States)

    Pelosi, Matteo

    The piston/cylinder lubricating interface represents one of the most critical design elements of axial piston machines. Being a pure hydrodynamic bearing, the piston/cylinder interface fulfills simultaneously a bearing and sealing function under oscillating load conditions. Operating in an elastohydrodynamic lubrication regime, it also represents one of the main sources of power loss due to viscous friction and leakage flow. An accurate prediction of the time changing tribological interface characteristics in terms of fluid film thickness, dynamic pressure field, load carrying ability and energy dissipation is necessary to create more efficient interface designs. The aim of this work is to deepen the understanding of the main physical phenomena defining the piston/cylinder fluid film and to discover the impact of surface elastic deformations and heat transfer on the interface behavior. For this purpose, a unique fully coupled multi-body dynamics model has been developed to capture the complex fluid-structure interaction phenomena affecting the non-isothermal fluid film conditions. The model considers the squeeze film effect due to the piston micro-motion and the change in fluid film thickness due to the solid boundaries elastic deformations caused by the fluid film pressure and by the thermal strain. The model has been verified comparing the numerical results with measurements taken on special designed test pumps. The fluid film calculated dynamic pressure and temperature fields have been compared. Further validation has been accomplished comparing piston/cylinder axial viscous friction forces with measured data. The model has been used to study the piston/cylinder interface behavior of an existing axial piston unit operating at high load conditions. Numerical results are presented in this thesis.

  15. Mechanical and thermal analysis of the internal combustion engine piston using Ansys

    Science.gov (United States)

    Cioată, V. G.; Kiss, I.; Alexa, V.; Raţiu, S. A.

    2017-01-01

    The piston is one of the most important components of the internal combustion engine. Piston fail mainly due to mechanical stresses and thermal stresses. In this paper is determined by using the finite element method, stress and displacement distribution due the flue gas pressure and temperature, separately and combined. The FEA is performed by CAD and CAE software. The results are compared with those obtained by the analytical method and conclusions have been drawn.

  16. Control scheme for power modulation of a free piston Stirling engine

    Science.gov (United States)

    Dhar, Manmohan

    1989-01-01

    The present invention relates to a control scheme for power modulation of a free-piston Stirling engine-linear alternator power generator system. The present invention includes connecting an autotransformer in series with a tuning capacitance between a linear alternator and a utility grid to maintain a constant displacement to piston stroke ratio and their relative phase angle over a wide range of operating conditions.

  17. Wear of hard materials by hard particles

    Energy Technology Data Exchange (ETDEWEB)

    Hawk, Jeffrey A.

    2003-10-01

    Hard materials, such as WC-Co, boron carbide, titanium diboride and composite carbide made up of Mo2C and WC, have been tested in abrasion and erosion conditions. These hard materials showed negligible wear in abrasion against SiC particles and erosion using Al2O3 particles. The WC-Co materials have the highest wear rate of these hard materials and a very different material removal mechanism. Wear mechanisms for these materials were different for each material with the overall wear rate controlled by binder composition and content and material grain size.

  18. Comparison of free-piston Stirling engine model predictions with RE1000 engine test data

    Science.gov (United States)

    Tew, R. C.

    1984-01-01

    Predictions of a free-piston Stirling engine model are compared with RE1000 engine test data taken at NASA-Lewis Research Center. The model validation and the engine testing are being done under a joint interagency agreement between the Department of Energy's Oak Ridge National Laboratory and NASA-Lewis. A kinematic code developed at Lewis was upgraded to permit simulation of free-piston engine performance; it was further upgraded and modified at Lewis and is currently being validated. The model predicts engine performance by numerical integration of equations for each control volume in the working space. Piston motions are determined by numerical integration of the force balance on each piston or can be specified as Fourier series. In addition, the model Fourier analyzes the various piston forces to permit the construction of phasor force diagrams. The paper compares predicted and experimental values of power and efficiency and shows phasor force diagrams for the RE1000 engine displacer and piston. Further development plans for the model are also discussed.

  19. NOISE IDENTIFICATION FOR HYDRAULIC AXIAL PISTON PUMP BASED ON ARTIFICIAL NEURAL NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The noise identification model of the neural networks is established for the 63SCY14-1B hydraulic axial piston pump. Taking four kinds of different port plates as instances, the noise identification is successfully carried out for hydraulic axial piston pump based on experiments with the MATLAB and the toolbox of neural networks. The operating pressure, the flow rate of hydraulic axial piston pump, the temperature of hydraulic oil, and bulk modulus of hydraulic oil are the main parameters having influences on the noise of hydraulic axial piston pump. These four parameters are used as inputs of neural networks, and experimental data of the noise are used as outputs of neural networks. Error of noise identification is less than 1% after the neural networks have been trained. The results show that the noise identification of hydraulic axial piston pump is feasible and reliable by using artificial neural networks. The method of noise identification with neural networks is also creative one of noise theoretical research for hydraulic axial piston pump.

  20. The ecological quasi-turbine, the best of the piston and the turbine[The supremacy of piston engines questioned; La suprematie du moteur a pistons remise en cause]; La quasiturbine ecologique, le meilleur du piston et de la turbine

    Energy Technology Data Exchange (ETDEWEB)

    Saint-Hilaire, R.; Saint-Hilaire, Y.; Saint-Hilaire, G.; Saint-Hilaire, F.

    2001-07-01

    This book presents the theory that forms the basis for quasi-turbines. The quasi-turbine is the culmination of three modern engines: it takes its inspiration from the turbine, perfects the piston, and improves Wankel engines. The quasi-turbine eliminates idle time by modifying the allocations to the various engine strokes and by replacing the progressive torque impulses by plateau impulses. The quasi-turbine optimizes engine performance with an almost constant instantaneous engine torque. The quasi-turbine can be powered by different fuels, including fossil fuels, steam, solar thermal, hydrogen, or diesel. There are several constraints associated with the quasi-turbine theory, each of which was discussed in turn. The quasi-turbine consists of four carriages which support the pivots of four pivoting blades of a variable shaped rotor and which roll as a roller bearing on the interior contour wall of a skating rink-like surface. This surface is also referred to as the Saint-Hilaire confinement profile. Engine technology is improved by increasing the mobile components utilization factor, eliminating all dead times, eliminating the excessive volume during expansion or power stroke, optimizing engine time management, allowing less time for compression and exhaust strokes, and by allowing more time and volume for intake and expansion strokes. The quasi-turbine engine satisfies the criteria of the envisioned hydrogen engine of the future. figs.

  1. Progress in High Power Free-Piston Stirling Convertor Development

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Kirby, Raymond L.; Chapman, Peter A.; Walter, Thomas J.

    2008-01-01

    The U.S. Space Exploration Policy has established a vision for human exploration of the moon and Mars. One option for power for future outposts on the lunar and Martian surfaces is a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kWe. A 25 kW convertor was developed in the 1990s under the SP-100 program. This system consisted of two 12.5 kWe engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA began a new project with Auburn University to develop a 5 kWe, single convertor for use in such a possible lunar power system. Goals of this development program include a specific power in excess of 140 We/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Foster-Miller, Inc. is developing the 5 kWe Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  2. Advanced Controller for the Free-Piston Stirling Convertor

    Science.gov (United States)

    Gerber, Scott S.; Jamison, Mike; Roth, Mary Ellen; Regan, Timothy F.

    2004-01-01

    The free-piston Stirling power convertor is being considered as an advanced power conversion technology to be used for future NASA deep space missions requiring long life radioisotope power systems. This technology has a conversion efficiency of over 25%, which is significantly higher than the efficiency of the Radioisotope Thermal-electric Generators (RTG) now in use. The NASA Glenn Research Center has long been recognized as a leader in Stirling technology and is responsible for the development of advanced technologies that are intended to significantly improve key characteristics of the Stirling convertor. The advanced technologies identified for development also consider the requirements of potential future missions and the new capabilities that have become available in the associated technical areas. One of the key areas identified for technology development is the engine controller. To support this activity, an advanced controller is being developed for the Stirling power convertor. This controller utilizes active power factor correction electronics and microcontroller-based controls. The object of this paper is to present an overview of the advanced controller concept with modeling, simulation and hardware test data.

  3. Progress in High Power Free-Piston Stirling Convertor Development

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Kirby, Raymond L.; Chapman, Peter A.; Walter, Thomas J.

    2008-09-01

    The U.S. Space Exploration Policy has established a vision for human exploration of the moon and Mars. One option for power for future outposts on the lunar and Martian surfaces is a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kWe. A 25 kW convertor was developed in the 1990s under the SP-100 program. This system consisted of two 12.5 kWe engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA began a new project with Auburn University to develop a 5 kWe, single convertor for use in such a possible lunar power system. Goals of this development program include a specific power in excess of 140 We/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Foster-Miller, Inc. is developing the 5 kWe Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  4. LED Monitoring System of the Phenix Muon Piston Calorimeter

    Science.gov (United States)

    Motschwiller, Steven

    2010-11-01

    The Muon Piston Calorimeter in the PHENIX experiment at RHIC has a monitoring system consisting of LEDs and PIN diodes to calibrate out the time dependent changes to the detector. The LEDs track the temperature and radiation-damage changes to the response of the MPC, while the absolute calibration can be done using 0̂ decays. To execute this, LEDs flash light through the PbWO4 crystal to the Avalanche Photo Diodes The MPC is made up of 416 independent electromagnetic calorimeter towers. By using the LEDs we can correct for changes in the gains of each tower in the MPC, on a run by run basis. Because the LED value only gives a relative measurement of the gain over time, this method of calibration can only be used in conjunction with absolute calibrations provided by 0̂ decays or by minimum ionizing peaks . This work will be used to make a final measurement on Transverse energy at √sNN = 200 GV in Au+Au collisions.

  5. The Influence of Cylinder Lubrication on Piston Slap

    Science.gov (United States)

    Gerges, S. N. Y.; de Luca, J. C.; Lalor, N.

    2002-10-01

    A model has been developed for determining the time history of piston slap impact force. This model takes into account the influence of the oil film on the impact behaviour, which was found to be an important factor. However, it was also found that entrapped gas bubbles in the oil are equally significant. Three test rigs were designed and built to study these effects on the impact phenomenon and extensive tests were carried out. The impact force time history has been determined using Reynolds' theory. Results have shown that Reynolds' theory for fluid film squeezing can be applied for oil film damping determination. However, the experimental results have also shown that when gas is entrapped during the impact, this theory considerably overpredicts the magnitude of the impact. An eight-degree-of-freedom lumped parameter model was developed through the dynamic analysis of each component of an internal combustion engine's reciprocating system. The effective damping factor derived from this model was found to be inversely proportional to the oil film thickness cubed, as expected from Reynolds' theory. A dynamic model has been proposed, where the oil film mixed with bubbles is considered to be analogous to a serial spring and damping system. By incorporating a spring in series with this damper, the effect of the bubbles can also be predicted.

  6. Abrasive Wear Map of Polymer Tapes in Sand Dust Environment

    Institute of Scientific and Technical Information of China (English)

    WU Tong-hai; DIAO Dong-feng

    2006-01-01

    To make clear the wear conditions of ATM (Automatic Teller Machine) tribosystem when servicing in Chinese sand dust environment, abrasive wear of two kinds of polymer tapes specified for ATM, PI (Polyimide) and PEN (Polyethylene-2, 6-naphthalenedicarboxylate), was investigated in simulated sand dust environment with ATM tape-scraper tribosystem under various conditions of loads and sliding distances. The surface profiles of worn tape were measured with a surface profiler in order to calculating the wear cross-section areas and the wear volumes. The specific wear rates of polymer tapes were calculated under load conditions of 0.6, 1 and 1.5 N, and wear mechanisms were investigated with optical topography photos. As main results, the specific wear rates show stage variations in the wear process and the wear resistance of polymer tape shows good relationship with the mechanical deformation factors. In consideration of the service life, four wear models are generalized according to the magnitude of specific wear rates,which include no wear, mild wear, normal wear and severe wear model and the corresponding wear mechanisms for the four wear models are discussed with typical worn topographies. Based on the wear models and corresponding wear mechanisms, the abrasive wear maps of two polymer tapes servicing in sand dust environments are concluded for its industrial applications.

  7. 聚醚醚酮复合材料耐磨性能的研究进展%RESEARCH DEVELOPMENT ON THE WEAR-RESISTING PERFORMANCE OF PEEK COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    张志丹; 徐娟; 孙克原; 宁冲冲; 吴银财; 崔益华; 杨文光; 陈佩民; 靳予

    2013-01-01

    聚醚醚酮(PEEK)作为80年代开发的一种全芳香族半结晶性的特殊工程塑料,具有耐化学腐蚀、耐高温、自润滑性、阻燃性、耐剥离性、耐疲劳性、机械性能好等特点,在航天航空、汽车、船舶、电子、医疗等领域得到了广泛的应用,但其耐磨性能仍然不能满足某些特殊用途,如抗疲劳和抗冲击零部件的要求.因此,对PEEK进行改性处理,从而可以得到力学性能或耐磨性能更加优异的PEEK塑料合金或PEEK复合材料.本文综述了聚醚醚酮复合材料耐磨性能的改善方法及其磨损机理.%In recent years, high performance thermoplastic polymer matrix composites have attracted the attention of researchers. Polymer based composites are being more and more used as tribomaterials due to their light weights and good tribological performances especially under dry sliding conditions. Poly ( ether ether ketone) , which is developed in 80s, is an attractive material for journal bearing and piston rings under various loading conditions as it exhibits a low creep rate at higher temperatures. Also, it has a high glass transition temperature (Tg: a-bout 143℃) and a high melting temperature (Tm:about 343℃). In addition, PEEK as a semi-crystalline special engineering plastic has many performances, for example, excellent chemical resistance, thermal stability, self-lubricating property, fire resistance, stripped resistance and fatigue durability, high strength, modulus and retention of mechanical properties over a wide temperature range and extreme environmental conditions, which is widely used in aircraft structures, space structural components of space research vehicles, automobile, ship, electronic / microelectronics , medical treatment and so on. But the wear resistance of PEEK still cannot meet the conditions in some special area, such as the request of the parts of the fatigue resistance and impact resistance. So, more and more excellent wear-resisting or

  8. Effects of fibrous fillers on friction and wear properties of polytetrafluoroethylene composites under dry or wet conditions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The friction and wear behavior and mechanism as well as the mechanical properties of polytetrafluoroethylene (PTFE) composites filled with potassium titanate whiskers (PTW) and short carbon fibers (CF) under dry, wet and alkaline conditions were investigated. Experiments indicated that owing to appropriate cooling and boundary lubricating effects, the filled PTFE composites showed much lower frictional coefficient and better wear resistance under alkaline than dry and wet sliding conditions. The wear resistance of carbon-fiber-filled PTFE was much better than that of potassium titanate-whisker-filled PTFE composites in water. Results also showed that the transfer film on counterpart rings was significantly hindered by water and alkali. Hydrophilic-filler-reinforced PTFE composites yield higher wear rate when sliding under water.

  9. On JB-Rings

    Institute of Scientific and Technical Information of China (English)

    Huanyin CHEN

    2007-01-01

    A ring R is a QB-ring provided that aR + bR = R with a, b ∈ R implies that there exists a y ∈ R such that a+by ∈ R-1q. It is said that a ring R is a JB-ring provided that R/J(R) is a QB-ring, where J(R) is the Jacobson radical of R. In this paper, various necessary and sufficient conditions, under which a ring is a JB-ring, are established. It is proved that JB-rings can be characterized by pseudo-similarity. Furthermore, the author proves that R is a J B-ring iff so is R/J(R)2.

  10. Effect of austempering process on microstructure and wear behavior of ductile iron containing Mn-Ni-Cu-Mo

    Science.gov (United States)

    PourAsiabi, HaMiD; Saghafian, Hasan; Pourasiabi, Hamed

    2013-01-01

    In this work, the effects of austempering time and temperature on the microstructure and sliding wear behavior of a Mn-Ni-Cu-Mo alloyed ductile iron were investigated. Ductile iron samples with the desired chemical composition were cast according to ASTM A897M-1990 Y-block. Wear test samples austenitized at 900 °C for 90 min, were austempered at 260, 290 and 320 °C for 30, 60, 90 and 120 min. The wear tests on samples were conducted by Block-on-Ring testing machine according to ASTM G77-98 standard, at the applied load of 75N and the displacement speed of 3.27 m/s. The results showed that the sample austempered at 260 °C for 90 min exhibited the maximum relative wear resistance in comparison with the as-cast sample. The X-ray diffraction patterns of wear debris and the SEM observations of worn surfaces and crosssection of worn surfaces together with wear debris showed that delamination associated with oxidation is the dominant wear mechanism in the samples.

  11. On semi ring bornologies

    Science.gov (United States)

    Imran, A. N.; Rakhimov, I. S.; Husain, Sh. K. Said

    2016-06-01

    Our main focus in this work is to introduce new structure bornological semi rings. This generalizes the theory of algebraic semi rings from the algebraic setting to the framework of bornological sets. We give basic properties for this new structure. As well as, We study the fundamental construction of bornological semi ring as product, inductive limits and projective limits and their extensions on bornological semi ring. Additionally, we introduce the category of bornological semi rings and study product and pullback (fiber product) in the category of bornological semi rings.

  12. Finite-temperature Casimir pistons for an electromagnetic field with mixed boundary conditions and its classical limit

    Energy Technology Data Exchange (ETDEWEB)

    Teo, L P [Faculty of Information Technology, Multimedia University, Jalan Multimedia, Cyberjaya, 63100, Selangor Darul Ehsan (Malaysia)], E-mail: lpteo@mmu.edu.my

    2009-03-13

    In this paper, the finite-temperature Casimir force acting on a two-dimensional Casimir piston due to an electromagnetic field is computed. It was found that if mixed boundary conditions are assumed on the piston and its opposite wall, then the Casimir force always tends to restore the piston toward the equilibrium position, regardless of the boundary conditions assumed on the walls transverse to the piston. In contrast, if pure boundary conditions are assumed on the piston and the opposite wall, then the Casimir force always tends to pull the piston toward the closer wall and away from the equilibrium position. The nature of the force is not affected by temperature. However, in the high-temperature regime, the magnitude of the Casimir force grows linearly with respect to temperature. This shows that the Casimir effect has a classical limit as has been observed in other literature.

  13. Enamel wear opposing polished and aged zirconia.

    Science.gov (United States)

    Burgess, J O; Janyavula, S; Lawson, N C; Lucas, T J; Cakir, D

    2014-01-01

    Aging of dental zirconia roughens its surface through low temperature degradation. We hypothesized that age-related roughening of zirconia crowns may cause detrimental wear to the enamel of an opposing tooth. To test our hypothesis, we subjected artificially aged zirconia and reference specimens to simulated mastication in a wear device and measured the wear of an opposing enamel cusp. Additionally, the roughness of the pretest surfaces was measured. The zirconia specimens, artificially aged by autoclave, showed no significant increase in roughness compared to the nonaged specimens. Furthermore, no significant difference in material or opposing enamel wear between the aged and nonaged zirconia was seen. All zirconia specimens showed less material and opposing enamel wear than the enamel to enamel control or veneering porcelain specimens. Scanning electron micrographs showed relatively smooth surfaces of aged and nonaged zirconia following wear testing. The micrographs of the veneering ceramic showed sharp fractured edges and fragments of wear debris. Zirconia may be considered a wear-friendly material for restorations opposing enamel, even after simulated aging.

  14. Numerical prediction of car tire wear

    NARCIS (Netherlands)

    Lupker, H.A.; Cheli, F.; Braghin, F.; Gelosa, E.; Keckman, A.

    2004-01-01

    Due to their many economic and ecological implications, the possibility to predict tire wear is of major importance to tire manufacturers, fleet owners and governments. Based on these observations, in 2000, a three-year project named TROWS (Tire and Road Wear and Slip assessment was started. One of

  15. Concrete ice abrasion rig and wear measurements

    NARCIS (Netherlands)

    Shamsutdinova, G.; Rike, P.B.; Hendriks, M.A.N.; Jacobsen, S.

    2015-01-01

    The wear of concrete material due to ice movement is a challenge for offshore and coastal structures. Concrete surfaces exposed to moving ice are subjected to wear at various rates depending on concrete and ice properties. At NTNU, Department of Structural Engineering, concrete ice abrasion phenomen

  16. Wear and microstructure in fine ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Vijande-Diaz, R.; Belzunce, J.; Fernandez, E. (ETS de Ingenieros Industriales, Area de Ingeneria Mecanica, Gijon (Spain)); Rincon, A.; Perez, M.C. (Inst. de Fisica-Quimica ' Roco Solano' , CSIC, Madrid (Spain))

    1991-08-15

    This paper presents a study of the wear resistance of two ceramic, plasma sprayed coatings of Al{sub 2}O{sub 3} and Cr{sub 2}O{sub 3}. Tests were carried out using an LWF-1 standard machine, with lineal contact, under dry friction, abrasion and lubricant conditions. The purpose of the tests were to study how load and speed affect material wear. Results show the lower wear rate of the ceramic coating compared with the steel one, as well as how remarkably load affects wear. On the other hand, however, considering the speed ranges used, wear resistance does not depend significantly on speed. The paper proves that the wear process follows Czichos' law. At the same time, reformulation of Archard's equation allows us to quantify wear using easily measurable factors such as pressure, speed, hardness, and those factors typically featuring this type of coatings, e.g. porosity. Also, a micrographic study of the coatings carried out by means of a scanning electron microscope has evidenced three stages in the wear mechanism: (a) plastic deformation of particles; (b) crack nucleation and propagation; and (c) loosening of ceramic particles. (orig.).

  17. Contact lens wear is intrinsically inflammatory.

    Science.gov (United States)

    Efron, Nathan

    2017-01-01

    Eye-care practitioners typically associate ocular inflammation during contact lens wear with serious complications such as microbial keratitis; however, more subtle mechanisms may be at play. This paper tests the notion that contact lens wear is intrinsically inflammatory by exploring whether uncomplicated contact lens wear meets the classical, clinical definition of inflammation - rubor (redness), calor (heat), tumor (swelling), dolor (pain) and functio laesa (loss of function) - as well as the contemporary, sub-clinical definition of inflammation (cellular and biochemical reactions). It is demonstrated that all of these clinical and sub-clinical criteria are met with hydrogel lens wear and most are met with silicone hydrogel lens wear, indicating that uncomplicated contact lens wear is intrinsically inflammatory. Consideration of both traditional and contemporary thinking about the role of inflammation in the human body leads to the perhaps surprising conclusion that the chronic, low grade, sub-clinical inflammatory status of the anterior eye during contact lens wear, which may be termed 'para-inflammation', is a positive, protective phenomenon, whereby up-regulation of the immune system, in a non-damaging way, maintains the eye in a state of 'heightened alert', ready to ward off any extrinsic noxious challenge. Characterisation of this inflammatory status may lead to the development of lens engineering or pharmacological strategies to modulate contact lens-induced inflammation, so as to render lens wear more safe and comfortable. © 2016 Optometry Australia.

  18. Inhibition of erosive wear by fluoride varnish

    NARCIS (Netherlands)

    Vieira, A.; Jager, D. H. J.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.

    2007-01-01

    It has been suggested that fluoride products with a protective mechanical component are advantageous in the prevention of erosive wear. The aim of this study was to evaluate in situ the effect of fluoride varnish (FV) in the prevention of wear due to erosion and combined erosion and toothbrush abras

  19. Concrete ice abrasion rig and wear measurements

    NARCIS (Netherlands)

    Shamsutdinova, G.; Rike, P.B.; Hendriks, M.A.N.; Jacobsen, S.

    2015-01-01

    The wear of concrete material due to ice movement is a challenge for offshore and coastal structures. Concrete surfaces exposed to moving ice are subjected to wear at various rates depending on concrete and ice properties. At NTNU, Department of Structural Engineering, concrete ice abrasion phenomen

  20. Friction and Wear Behaviors of Nanostructured Metals

    Institute of Scientific and Technical Information of China (English)

    Zhong HAN; Yusheng ZHANG; Ke LU

    2008-01-01

    Nanostructured (ns) materials, i.e., polycrystalline materials with grain sizes in the nanometer regime (typically below 100 nm), have drawn considerable attention in the past decades due to their unique properties such as high strength and hardness. Wear resistance of ns materials, one of the most important properties for engineering materials, has been extensively investigated in the past decades. Obvious differences have been identified in friction and wear behaviors Between the ns materials and their corresponding coarse-grained (cg) counterparts, consistently correlating with their unique structure characteristics and mechanical properties. On the other hand, the superior tribological properties of ns materials illustrate their potential applications under contact loads. The present overview will summarize the important progresses achieved on friction and wear behaviors of ns metallic materials, including ultrafine-grained (ufg) materials in recent years. Tribological properties and effects on friction and wear behaviors of ns materials will be discussed under different wear conditions including abrasive wear, sliding wear, and fretting wear. Their correlations with mechanical properties will be analyzed. Perspectives on development of this field will be highlighted as well.

  1. Inhibition of erosive wear by fluoride varnish

    NARCIS (Netherlands)

    Vieira, A.; Jager, D. H. J.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.

    2007-01-01

    It has been suggested that fluoride products with a protective mechanical component are advantageous in the prevention of erosive wear. The aim of this study was to evaluate in situ the effect of fluoride varnish (FV) in the prevention of wear due to erosion and combined erosion and toothbrush

  2. Wear and transfer characteristics of carbon fiber reinforced polymer composites under water lubrication

    Institute of Scientific and Technical Information of China (English)

    JIA Jun-hong; CHEN Jian-min; ZHOU Hui-di; CHEN Lei

    2004-01-01

    The tribological characteristics of carbon fiber reinforced polymer composites under distilled-water-lubricated-sliding and dry-sliding against stainless steel were comparatively investigated. Scanning electron microscopy (SEM) was utilized to examine composite microstructures and modes of failure. The typical chemical states of elements of the transfer film on the stainless steel were examined with X-ray photoelectron spectroscopy (XPS). Wear testing and SEM analysis show that all the composites hold the lowered friction coefficient and show much better wear resistance under water lubricated sliding against stainless steel than those under dry sliding. The wear of composites is characterized by plastic deformation, scuffing, micro cracking, and spalling under both dry-sliding and water lubricated conditions. Plastic deformation, scuffing, micro cracking, and spalling, however, are significantly abated under water-lubricated condition. XPS analysis conforms that none of the materials produces transfer films on the stainless steel counterface with the type familiar from dry sliding, and the transfer of composites onto the counterpart ring surface is significantly hindered while the oxidation of the stainless steel is speeded under water lubrication. The composites hinder transfer onto the steel surface and the boundary lubricating action of water accounts for the much smaller wear rate under water lubrication compared with that under dry sliding. The easier transfer of the composite onto the counterpart steel surface accounts for the larger wear rate of the polymer composite under dry sliding.

  3. Influence of composition on friction-wear behavior of composite materials reinforced by brass fibers

    Institute of Scientific and Technical Information of China (English)

    JIA Xian; LING Xiaomei

    2003-01-01

    In the study, for the composite materials reinforced by brass fibers, the influence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber, and graphite powder, on the friction-wear characteristics was investigated. The friction-wear experiment was carried out on the block-on-ring tribometer MM200. The worn surfaces of the friction pair consisting of the composite materials and grey cast iron HT200 under dry sliding friction were examined using scanning electron microscope (SEM), energy dispersive analysis (EDX) and differential thermal analysis-thermogravimetric analysis (DTA-TAG). The experimental results showed that the friction coefficient and the wear loss of the composite material increase obviously with the increase of cast iron debris content, but decrease obviously with the increase of graphite powder content, and increase a little when the mass fraction of brass fiber was over 19%, and the orientation of brass fiber has obvious influence on friction-wear property. When the mass fraction of organic adhesion agent was about 10-11%, the composite materials have an excellent friction-wear performance. The friction heat can pyrolyze organic ingredient in worn surface layer.

  4. Wear behavior of Ni/WC surface-infiltrated composite coating on copper substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Gui-rong; Ma, Ying; Hao, Yuan [Lanzhou University of Technology, Gansu (China). State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals; Song, Wen-ming [Lanzhou University of Technology, Gansu (China). State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals; Lanzhou Petroleum Machinery Institute, Gansu (China); Li, Jian [Wuhan Research Institute of Materials Protection (China); Lu, Jin-jun [Chinese Academy of Sciences, Lanzhou, Gansu (China). State Key Laboratory of Solid Lubrication

    2016-01-15

    Ni/WC surface-infiltrated composite coating was fabricated on copper alloy substrate through vacuum infiltration casting using Ni-based alloying powder and with different WC particle contents as raw materials. The wear behavior of Ni/WC surface-infiltrated composite coating was investigated using a block-on-ring tester at different loads and sliding speeds at room temperature. Results show that the wear rate of Ni/WC surface-infiltrated composite coating decreased to approximately one-sixth of the wear rate of the Ni-based alloy infiltrated coating. This phenomenon resulted from the supporting function of WC particles under varying loads applied on the specimen surface and the antifriction effect of the transformation layer. Wear rate was reduced by the Ni/WC-infiltrated composite coating with increasing load, especially when the load exceeded 100 N. The friction coefficient decreased with increasing sliding speed for all infiltrated coatings at any load condition. The reduction in the friction coefficient at high sliding speed was larger than that at low sliding speed with increasing load. The wear mechanism was dominated by oxidation under all experimental conditions and accompanied by adhesion and abrasion mechanisms at high load and high sliding speed.

  5. Space Power Free-Piston Stirling Engine Scaling Study

    Science.gov (United States)

    Jones, D.

    1989-01-01

    The design feasibility study is documented of a single cylinder, free piston Stirling engine/linear alternator (FPSE/LA) power module generating 150 kW-electric (kW sub e), and the determination of the module's maximum feasible power level. The power module configuration was specified to be a single cylinder (single piston, single displacer) FPSE/LA, with tuning capacitors if required. The design requirements were as follows: (1) Maximum electrical power output; (2) Power module thermal efficiency equal to or greater than 20 percent at a specific mass of 5 to 8 kg/kW(sub e); (3) Heater wall temperature/cooler wall temperature = 1050 K/525 K; (4) Sodium heat-pipe heat transport system, pumped loop NaK (sodium-potassium eutectic mixture) rejection system; (5) Maximum power module vibration amplitude = 0.0038 cm; and (6) Design life = 7 years (60,000 hr). The results show that a single cylinder FPSE/LA is capable of meeting program goals and has attractive scaling attributes over the power range from 25 to 150 kW(sub e). Scaling beyond the 150 kW(sub e) power level, the power module efficiency falls and the power module specific mass reaches 10 kg/kW(sub e) at a power output of 500 kW(sub e). A discussion of scaling rules for the engine, alternator, and heat transport systems is presented, along with a detailed description of the conceptual design of a 150 kW(sub e) power module that meets the requirements. Included is a discussion of the design of a dynamic balance system. A parametric study of power module performance conducted over the power output range of 25 to 150 kW(sub e) for temperature ratios of 1.7, 2.0, 2.5, and 3.0 is presented and discussed. The results show that as the temperature ratio decreases, the efficiency falls and specific mass increases. At a temperature ratio of 1.7, the 150 kW(sub e) power module cannot satisfy both efficiency and specific mass goals. As the power level increases from 25 to 150 kW(sub e) at a fixed temperature ratio, power

  6. Biologically Based Restorative Management of Tooth Wear

    Directory of Open Access Journals (Sweden)

    Martin G. D. Kelleher

    2012-01-01

    Full Text Available The prevalence and severity of tooth wear is increasing in industrialised nations. Yet, there is no high-level evidence to support or refute any therapeutic intervention. In the absence of such evidence, many currently prevailing management strategies for tooth wear may be failing in their duty of care to first and foremost improve the oral health of patients with this disease. This paper promotes biologically sound approaches to the management of tooth wear on the basis of current best evidence of the aetiology and clinical features of this disease. The relative risks and benefits of the varying approaches to managing tooth wear are discussed with reference to long-term follow-up studies. Using reference to ethical standards such as “The Daughter Test”, this paper presents case reports of patients with moderate-to-severe levels of tooth wear managed in line with these biologically sound principles.

  7. Modeling wear of cast Ti alloys.

    Science.gov (United States)

    Chan, Kwai S; Koike, Marie; Okabe, Toru

    2007-05-01

    The wear behavior of Ti-based alloys was analyzed by considering the elastic-plastic fracture of individual alloys in response to the relevant contact stress field. Using the contact stresses as the process driving force, wear was computed as the wear rate or volume loss as a function of hardness and tensile ductility for Ti-based cast alloys containing an alpha, alpha+beta or beta microstructure with or without the intermetallic precipitates. Model predictions indicated that wear of Ti alloys increases with increasing hardness but with decreasing fracture toughness or tensile ductility. The theoretical results are compared with experimental data to elucidate the roles of microstructure in wear and contrasted against those in grindability.

  8. Assessment of variations in wear test methodology.

    Science.gov (United States)

    Gouvêa, Cresus V D; Weig, Karin; Filho, Thales R M; Barros, Renata N

    2010-01-01

    The properties of composite resin for dental fillings were improved by development, but its weakness continues to be its wear strength. Several tests have been proposed to evaluate wear in composite resin materials. The aim of this study was to verify how polishing and the type of abrasive can influence the wear rate of composite resin. The test was carried out on two groups. In one group we employed an ormocer and a hybrid composite that was polished group the composite was polished with the same abrasive paper plus a 1 microm and 0.25 microm grit diamond paste. A three-body wear test was performed using the metal sphere of the wear test machine, the composite and an abrasive. A diamond paste and aluminum oxide dispersion were used as abrasive. Analysis of the results showed that there was no difference between polishing techniques, but revealed a difference between abrasives.

  9. Dynamic SEM wear studies of tungsten carbide cermets. [friction and wear experiments

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined, and etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the tungsten carbide (WC) and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation, and the wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation, and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  10. Asphalt wear and pollution transport

    Energy Technology Data Exchange (ETDEWEB)

    Lindgren, Asa [Division of Traffic Engineering, Lulea University of Technology Lulea (Sweden)

    1996-09-06

    Studded tires cause extensive wear of road surfaces during winter producing small particles. Besides transporting different adsorbed pollutants these particles also discharge metal ions by their own natural content. The major part (95%) of the asphalt is composed of stone fractions. The rest consists mainly of bitumen, which contains trace quantities of metals. Laboratory studies in this study have demonstrated different adsorbing properties of metal ions, as well as differences in adsorption when comparing stone materials. Two stone materials, a gabbro and a porphyry, have been tested for their adsorption properties concerning Pb, Cu, Zn and Cd. The gabbro showed better adsorption capacity than the porphyry. Gabbro has coarser grains, it is softer, and also has a higher content of most metals compared to the porphyry. In all tests lead and copper are more adsorbed than zinc and cadmium. All metal ions are released at about the same pH ({approx}4)

  11. Energetic aspects of boring tools wear

    Directory of Open Access Journals (Sweden)

    Lazarová Edita

    2002-03-01

    Full Text Available In the process of rock desintegration a boring tool is subjected to the wear. From a viewpoint of the bit wear, changes on the contact of operating tool with rock at its one-shot and rerun load or overload by external forces are technically significant. Theis change results in the degradation of bit working properties and the output of desintegration also decreases. In the major part of cases, together with the bit wear, the contact area of a tool with a rock massifs enhanced and this fact causes an increase of fines (dust creation during the desintegration. The wear is always connected with a friction, forces action, deformation, damage, and the increased mechanical work consumption. As to energetic aspects of bit wear, the wear was observed as a function of bore length and in the most of cases as a dependence of the operating time. A linear dependence between the wear intensity (bit wear per unit of bore length and the specific energy of desintegration (energy consumed per volume unit of desintegrated rock was experimentally verified. Thus, the changes of bit wear can be implicitly observed by monitoring the specific energy. At the same time, the specific energy is a function of input parameters of the desintegration process and in the field of applicable external forces it shows an extreme (minimum. Therefore, the specific energy is useful for the extreme optimisation of the rock desintegration process from the viewpoint of the bit wear. It was mathematically proven that the tool output at the desintegration exponentially decreases with the amount of work consumed in the rock desintegration. The derivation of this knowledge comes out from the Krendelev equation.

  12. Adhesive Wear of Rollers in Vacuum

    Science.gov (United States)

    Shaeef, Iqbal; Krantz, Timothy L.

    2012-01-01

    This work was done to support NASA's James Webb Space Telescope that is equipped with a Near Infrared Camera and Spectrograph and Micro Shutter Assembly (MSA). A MSA mechanism's qualification test in cryogenic vacuum at 30deg K for 96K cycles resulted in roller wear and formation of some debris. Lab tests in vacuum were conducted at NASA Glenn Research Center (GRC) to understand the wear of Ti6Al4V mated with 440F steel rollers. Misalignment angle was found to have the most significant effect on debris formation. At misalignment angle of 1.4deg, significant amount of wear debris were formed within 50,000 cycles. Very few wear particles were found for a zero misalignment angle, and the total wear was small even after 367,000 cycles. The mode of wear in all the tests was attributed to adhesion, which was clearly evident from video records as well as the plate-like amalgamated debris material from both rollers. The adhesive wear rate was found to be approximately proportional to the misalignment angle. The wear is a two-way phenomenon, and the mixing of both roller materials in wear debris was confirmed by x-ray fluorescence (XRF) and EDX spectra. While there was a net loss of mass from the steel rollers, XRF and energy dispersive x-ray (EDX) spectra showed peaks of Ti on steel rollers, and peaks of Fe on Ti rollers. These results are useful for designers in terms of maintaining appropriate tolerances to avoid misalignment of rolling elements and the resulting severe wear

  13. Fault Wear During Earthquake-Like Slip-Events in Laboratory Experiments

    Science.gov (United States)

    Reches, Z.; Chang, J. C.; Boneh, Y.; Lockner, D. A.

    2010-12-01

    We present fault-wear observations from experiments conducted on a rotary shear apparatus with samples made of solid rock of ring structure 7 cm in diameter and 1 cm wide.. The experimental procedure is designed to simulate the slip along a fault patch that is activated by an instantaneous shear loading associated with a propagating earthquake front. For this objective, the apparatus accumulates a finite amount of energy in a 225 kg flywheel that is engaged to the sample through a fast-acting clutch. Slip along the sample is initiated when the flywheel torque exceeds the critical strength of the sample, and the slip seized when the flywheel kinetic energy is consumed. During the experiment, we continuously monitored the fault slip-velocity, its surface closure, the normal and shear stresses across the fault, and its temperature. We present results of 34 experiments, 19 of them with Sierra White granite samples and 15 with Kasota dolomite samples. The samples were loaded under normal stress up to 7 MPa. In a typical experiment, the velocity rose quickly (measured closure across the fault blocks, and presented here by the unit W= [(micron of surface wear) / (meter of slip distance)] (see Boneh et al., this meeting). The maximum calculated wear-rate in these experiments approaches 20,000 microm/m. We recognized three distinct modes of wear-rate variations with respect to the measured friction: (1) An initial, short stage of high dilation-rate with slight (~10%) increase of the associated friction; this stage was followed by long period of low wear-rate accompanied with a moderate to large friction drop (30-50%); (2) Under relatively high peak velocities of 0.5-1.0 m/s, the samples displayed initial high wear-rate (fault-surface closure) that quickly decays to steady-state stage of low wear-rate; and (3) Under low slip-velocity conditions (velocity <0.1 m/s), the experimental fault did not display a discernable wear-rate pattern. The present experiments reveal large

  14. Groups, rings, modules

    CERN Document Server

    Auslander, Maurice

    2014-01-01

    This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

  15. Birth Control Ring

    Science.gov (United States)

    ... Right Sport for You Healthy School Lunch Planner Birth Control Ring KidsHealth > For Teens > Birth Control Ring Print A A A What's in ... español Anillo vaginal anticonceptivo What Is It? The birth control ring is a soft, flexible, doughnut-shaped ...

  16. On Weakly Semicommutative Rings*

    Institute of Scientific and Technical Information of China (English)

    CHEN WEI-XING; CUI SHU-YING

    2011-01-01

    A ring R is said to be weakly scmicommutative if for any a, b ∈ R,ab = 0 implies aRb C_ Nil(R), where Nil(R) is the set of all nilpotcnt elements in R.In this note, we clarify the relationship between weakly semicommutative rings and NI-rings by proving that the notion of a weakly semicommutative ring is a proper generalization of NI-rings. We say that a ring R is weakly 2-primal if the set of nilpotent elements in R coincides with its Levitzki radical, and prove that if R is a weakly 2-primal ring which satisfies oα-condition for an endomorphism α of R (that is, ab = 0 (←→) aα(b) = 0 where a, b ∈ R) then the skew polynomial ring R[π; αα]is a weakly 2-primal ring, and that if R is a ring and I is an ideal of R such that I and R/I are both weakly semicommutative then R is weakly semicommutative.Those extend the main results of Liang et al. 2007 (Taiwanese J. Math., 11(5)(2007),1359-1368) considerably. Moreover, several new results about weakly semicommutative rings and NI-rings are included.

  17. The optimal path of piston motion for Otto cycle with linear phenomenological heat transfer law

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    An Otto cycle engine with internal and external irreversibilities of friction and heat leakage, in which the heat transfer between the working fluid and the environment obeys linear phenomenological heat transfer law [q ∝△(T -1)], is studied in this paper. The optimal piston motion trajectory for maximizing the work output per cycle is derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and without piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum deceleration boundary segments, respectively. Numerical examples for optimal configuration are provided, and the obtained results are compared with those obtained with Newton’s heat transfer law [q ∝△(T )]. The results also show that optimizing the piston motion can improve power and efficiency of the engine by more than 9%. This is primarily due to the decrease in heat leakage loss on the initial portion of the power stroke.

  18. Modeling and Simulation on Axial Piston Pump Based on Virtual Prototype Technology

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bin; XU Bing; XIA Chunlin; YANG Huayong

    2009-01-01

    A particular emphasis is placed on the virtual prototype technology (VPT) of axial piston pump. With this technology it is convenient and flexible to build a complicated 3D virtual based on real physical model. The actual kinematics pairs of the parts were added on the model. The fluid characters were calculated by hydraulic software. The shape of the parts, the flexible body of parts, etc were improved in this prototype. So the virtual prototype of piston pump can work in computer like a real piston pump, and the flow ripple, pressure pulsation, motion principle, stress of parts, etc can be investigated. The development of the VPT is introduced at the beginning, and the modeling process of the virtual prototype is explained. Then a special emphasis is laid on the relationship between the dynamics model and the hydraulic model, and the simulations on the flow ripple, pressure pulsation, motion principle, the stress and strain distribution of the middle shaft and piston are operated. Finally, the advantages and disadvantages of the VPT are discussed. The improved virtual prototype of piston pump more tally with the real situation and the VPT has a great potential in simulation on hydraulic components.

  19. Compact high-efficiency linear cryocooler in single-piston moving magnet design for HOT detectors

    Science.gov (United States)

    Rühlich, I.; Mai, M.; Rosenhagen, C.; Withopf, A.; Zehner, S.

    2012-06-01

    State of the art Mid Wave IR-technology has the potential to rise the FPA temperature from 77K to 130-150K (High Operation Temperature, HOT). Using a HOT FPA will significantly lower SWaP and keep those parameters finally dominated by the employed cryocooler. Therefore, compact high performance cryocoolers are mandatory. AIM has developed the SX040 cooler, optimized for FPA temperatures of about 95K (presented at SPIE 2010). The SX040 cooler incorporates a high efficient dual piston driving mechanism resulting in a very compact compressor of less than 100mm length. Higher compactness - especially shorter compressors - can be achieved by change from dual to single piston design. The new SX030 compressor has such a single piston Moving Magnet driving mechanism resulting in a compressor length of about 60mm. Common for SX040 and SX030 family is a Moving Magnet driving mechanism with coils placed outside the helium vessel. In combination with high performance plastics for the piston surfaces this design enables lifetimes in excess of 20,000h MTTF. Because of the higher FPA temperature and a higher operating frequency also a new displacer needs to be developed. Based on the existing 1/4" coldfinger interface AIM developed a new displacer optimized for an FPA temperature of 140K and above. This paper gives an overview on the development of this new compact single piston cryocooler. Technical details and performance data will be shown.

  20. Efficiency at maximum power output for an engine with a passive piston

    Science.gov (United States)

    Sano, Tomohiko G.; Hayakawa, Hisao

    2016-08-01

    Efficiency at maximum power (MP) output for an engine with a passive piston without mechanical controls between two reservoirs is studied theoretically. We enclose a hard core gas partitioned by a massive piston in a temperature-controlled container and analyze the efficiency at MP under a heating and cooling protocol without controlling the pressure acting on the piston from outside. We find the following three results: (i) The efficiency at MP for a dilute gas is close to the Chambadal-Novikov-Curzon-Ahlborn (CNCA) efficiency if we can ignore the sidewall friction and the loss of energy between a gas particle and the piston, while (ii) the efficiency for a moderately dense gas becomes smaller than the CNCA efficiency even when the temperature difference of the reservoirs is small. (iii) Introducing the Onsager matrix for an engine with a passive piston, we verify that the tight coupling condition for the matrix of the dilute gas is satisfied, while that of the moderately dense gas is not satisfied because of the inevitable heat leak. We confirm the validity of these results using the molecular dynamics simulation and introducing an effective mean-field-like model which we call the stochastic mean field model.

  1. Simulating Rectified Motion of a Piston in a Housing Subjected to Vibrational Acceleration

    Science.gov (United States)

    Clausen, Jonthan; Torczynski, John; Romero, Louis; O'Hern, Timothy

    2014-11-01

    We employ ALE finite element simulations to investigate the behavior of a piston in a housing subjected to vertical vibrations. The housing is filled with a viscous liquid to damp the piston motion and has bellows at both ends to represent air bubbles present in real systems. The piston has a roughly cylindrical hole along its axis, and a post attached to the housing penetrates partway into this hole. Protrusions from the hole and the post form a gap with a length that varies as the piston moves and forces liquid through this gap. Under certain conditions, nonlinearities in the system can drive the piston to move downward and compress the spring that holds it up against gravity. This behavior is investigated using ALE finite element simulations, and these results are compared with theoretical predictions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  2. The optimal path of piston motion for Otto cycle with linear phenomenological heat transfer law

    Institute of Scientific and Technical Information of China (English)

    XIA ShaoJun; CHEN LinGen; SUN FengRui

    2009-01-01

    An Otto cycle engine with internal and external irreversibilities of friction and heat leakage, in which the heat transfer between the working fluid and the environment obeys linear phenomenological heat transfer law [q∝△(T-1)], is studied in this paper. The optimal piston motion trajectory for maximizing the work output per cycle is derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and without piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum deceleration boundary segments,respectively. Numerical examples for optimal configuration are provided, and the obtained results are compared with those obtained with Newton's heat transfer law [q∝△(T)]. The results also show that optimizing the piston motion can improve power and efficiency of the engine by more than 9%. This is primarily due to the decrease in heat leakage loss on the initial portion of the power stroke.

  3. Development of cryogenic free-piston reciprocating expander utilizing phase controller

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jeong Min; Park, Ji Ho; Kim, Kyung Joong; Jeong, Sang Kwon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2016-06-15

    A free-piston reciprocating expander is a device which operates without any mechanical linkage to a stationary part. Since the motion of the floating piston is only controlled by the pressure difference at two ends of the piston, this kind of expander may indispensably require a sophisticated active control system equipped with multiple valves and reservoirs. In this paper, we have suggested a novel design that can further reduce complexity of the previously developed cryogenic free-piston expander configuration. It is a simple replacement of both multiple valves and reservoirs by a combination of an orifice valve and a reservoir. The functional characteristic of the integrated orifice-reservoir configuration is similar to that of a phase controller applied in a pulse tube refrigerator so that we designate the one as a phase controller. Depending on the orifice valve size in the phase controller, the different PV work which affects the expander performance is generated. The numerical model of this unique free-piston reciprocating expander utilizing a phase controller is established to understand and analyze quantitatively the performance variation of the expander under different valve timing and orifice valve size. The room temperature experiments are carried out to examine the performance of this newly developed cryogenic expander.

  4. Optimal paths of piston motion of irreversible diesel cycle for minimum entropy generation

    Directory of Open Access Journals (Sweden)

    Ge Yanlin

    2011-01-01

    Full Text Available A Diesel cycle heat engine with internal and external irreversibility’s of heat transfer and friction, in which the finite rate of combustion is considered and the heat transfer between the working fluid and the environment obeys Newton’s heat transfer law [q≈ Δ(T], is studied in this paper. Optimal piston motion trajectories for minimizing entropy generation per cycle are derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston motion trajectories for the cases of with piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum deceleration boundary segments, respectively. Numerical examples for optimal configurations are provided, and the results obtained are compared with those obtained when maximizing the work output with Newton’s heat transfer law. The results also show that optimizing the piston motion trajectories could reduce engine entropy generation by more than 20%. This is primarily due to the decrease in entropy generation caused by heat transfer loss on the initial portion of the power stroke.

  5. 对置活塞钻井泵机构原理及运动学分析%Mechanism Principle and Kinematic Analysis of the Opposed Piston Drilling Pump

    Institute of Scientific and Technical Information of China (English)

    王大庆; 李华; 姚进; 余德平

    2015-01-01

    合理降低钻井泵冲次可以提高钻井泵内活塞、活塞皮碗、缸套、泵阀等易损件的工作寿命,提高钻井泵可靠性,从而缩减钻井泵停车检修时间,提升钻井泵作业效率。提出了一种对置活塞结构泵,介绍了其结构及工作原理。与传统活塞钻井泵相比,在相同钻进作业流量需求场合,对置活塞泵冲次可以大大降低,理论上可减小50%;通过动力学分析软件的运动学仿真分析得出,对置活塞泵活塞速度幅值变化量减小50%,速度曲线波动程度减弱;加速度幅值变化量减小75%,加速度曲线波动程度减弱。在相同流量需求场合,对置活塞泵冲次更低,运转更加平稳。%By reducing the pump speed of the drilling pump reasonably,the service life of the quick-wear parts of the drilling pump such as the piston,the piston seal,the cylinder liner and the pump valve can be increased,thus the reliability of the drilling pump can be improved.Thus the time spent in repair work of the drilling pump can be reduced,and the pump efficiency can be im-proved.To reduce the pump speed reasonably is a promising trend for the drilling pump.Based on this,a new drilling pump with the opposed piston structure is proposed,the mechanism and opera-tion principle of the opposed piston pump (OPP)is introduced.Theoretical analysis concluded that with the same flow rate demand,the pump speed of the OPP could be reduced by half com-pared with that of the conventional drilling pump.The kinematic simulations based on dynamic software indicated that the velocity amplitude of the OPP piston reduced by 50%,the velocity fluctuation of the OPP piston significantly reduced compared with that of the conventional drilling pump,and the acceleration amplitude of the OPP piston reduced by 75%,the acceleration fluctua-tion of the OPP piston significantly reduced compared with that of the conventional drilling pump.Under the same flow rate demand

  6. Wear Characteristics of Metallic Biomaterials: A Review

    Directory of Open Access Journals (Sweden)

    Mohamed A. Hussein

    2015-05-01

    Full Text Available Metals are extensively used in a variety of applications in the medical field for internal support and biological tissue replacements, such as joint replacements, dental roots, orthopedic fixation, and stents. The metals and alloys that are primarily used in biomedical applications are stainless steels, Co alloys, and Ti alloys. The service period of a metallic biomaterial is determined by its abrasion and wear resistance. A reduction in the wear resistance of the implant results in the release of incompatible metal ions into the body that loosen the implant. In addition, several reactions may occur because of the deposition of wear debris in tissue. Therefore, developing biomaterials with high wear resistance is critical to ensuring a long life for the biomaterial. The aim of this work is to review the current state of knowledge of the wear of metallic biomaterials and how wear is affected by the material properties and conditions in terms of the type of alloys developed and fabrication processes. We also present a brief evaluation of various experimental test techniques and wear characterization techniques that are used to determine the tribological performance of metallic biomaterials.

  7. Free-Piston Stirling Power Conversion Unit for Fission Power System, Phase II Final Report

    Science.gov (United States)

    Wood, J. Gary; Stanley, John

    2016-01-01

    In Phase II, the manufacture and testing of two 6-kW(sub e)Stirling engines was completed. The engines were delivered in an opposed 12-kW(sub e) arrangement with a common expansion space heater head. As described in the Phase I report, the engines were designed to be sealed both hermetically and with a bolted O-ring seal. The completed Phase II convertor is in the bolted configuration to allow future disassembly. By the end of Phase II, the convertor had passed all of the final testing requirements in preparation for delivery to the NASA Glenn Research Center. The electronic controller also was fabricated and tested during Phase II. The controller sets both piston amplitudes and maintains the phasing between them. It also sets the operating frequency of the machine. Details of the controller are described in the Phase I final report. Fabrication of the direct-current to direct-current (DC-DC) output stage, which would have stepped down the main controller output voltage from 700 to 120 V(sub DC), was omitted from this phase of the project for budgetary reasons. However, the main controller was successfully built, tested with the engines, and delivered. We experienced very few development issues with this high-power controller. The project extended significantly longer than originally planned because of yearly funding delays. The team also experienced several hardware difficulties along the development path. Most of these were related to the different thermal expansions of adjacent parts constructed of different materials. This issue was made worse by the large size of the machine. Thermal expansion problems also caused difficulties in the brazing of the opposed stainless steel sodium-potassium (NaK) heater head. Despite repeated attempts Sunpower was not able to successfully braze the opposed head under this project. Near the end of the project, Glenn fabricated an opposed Inconel NaK head, which was installed prior to delivery for testing at Glenn. Engine

  8. Dimensional Description of On-line Wear Debris Images for Wear Characterization

    Institute of Scientific and Technical Information of China (English)

    WU Tonghai; PENG Yeping; DU Ying; WANG Junqun

    2014-01-01

    As one of the most wear monitoring indicator, dimensional feature of individual particles has been studied mostly focusing on off-line analytical ferrograph. Recent development in on-line wear monitoring with wear debris images shows that merely wear debris concentration has been extracted from on-line ferrograph images. It remains a bottleneck of obtaining the dimension of on-line particles due to the low resolution, high contamination and particle’s chain pattern of an on-line image sample. In this work, statistical dimension of wear debris in on-line ferrograph images is investigated. A two-step procedure is proposed as follows. First, an on-line ferrograph image is decomposed into four component images with different frequencies. By doing this, the size of each component image is reduced by one fourth, which will increase the efficiency of subsequent processing. The low-frequency image is used for extracting the area of wear debris, and the high-frequency image is adopted for extracting contour. Second, a statistical equivalent circle dimension is constructed by equaling the overall wear debris in the image into equivalent circles referring to the extracted total area and premeter of overall wear debris. The equivalent circle dimension, reflecting the statistical dimension of larger wear debris in an on-line image, is verified by manual measurement. Consequently, two preliminary applications are carried out in gasoline engine bench tests of durability and running-in. Evidently, the equivalent circle dimension, together with the previously developed concentration index, index of particle coverage area (IPCA), show good performances in characterizing engine wear conditions. The proposed dimensional indicator provides a new statistical feature of on-line wear particles for on-line wear monitoring. The new dimensional feature conveys profound information about wear severity.

  9. Physics of quantum rings

    CERN Document Server

    Fomin, Vladimir M

    2013-01-01

    This book deals with a new class of materials, quantum rings. Innovative recent advances in experimental and theoretical physics of quantum rings are based on the most advanced state-of-the-art fabrication and characterization techniques as well as theoretical methods. The experimental efforts allow to obtain a new class of semiconductor quantum rings formed by capping self-organized quantum dots grown by molecular beam epitaxy. Novel optical and magnetic properties of quantum rings are associated with non-trivial topologies at the nanoscale. An adequate characterization of quantum rings is po

  10. Envelopes of Commutative Rings

    Institute of Scientific and Technical Information of China (English)

    Rafael PARRA; Manuel SAOR(I)N

    2012-01-01

    Given a significative class F of commutative rings,we study the precise conditions under which a commutative ring R has an F-envelope.A full answer is obtained when.F is the class of fields,semisimple commutative rings or integral domains.When F is the class of Noetherian rings,we give a full answer when the Krull dimension of R is zero and when the envelope is required to be epimorphic.The general problem is reduced to identifying the class of non-Noetherian rings having a monomorphic Noetherian envelope,which we conjecture is the empty class.

  11. RING PROXY SIGNATURES

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Proxy signatures have been used to enable the transfer of digital signing power within some context and ring signatures can be used to provide the anonymity of a signer. By combining the functionalities of proxy signatures and ring signatures, this paper introduces a new concept, named ring proxy signature, which is a proxy signature generated by an anonymous member from a set of potential signers. The paper also constructs the first concrete ring proxy signature scheme based on the provably secure Schnorr's signatures and two ID-based ring proxy signature schemes. The security analysis is provided as well.

  12. Prediction of Wear in Crosslinked Polyethylene Unicompartmental Knee Arthroplasty

    Directory of Open Access Journals (Sweden)

    Jonathan Netter

    2015-05-01

    Full Text Available Wear-related complications remain a major issue after unicompartmental arthroplasty. We used a computational model to predict knee wear generated in vitro under diverse conditions. Inverse finite element analysis of 2 different total knee arthroplasty designs was used to determine wear factors of standard and highly crosslinked polyethylene by matching predicted wear rates to measured wear rates. The computed wear factor was used to predict wear in unicompartmental components. The articular surface design and kinematic conditions of the unicompartmental and tricompartmental designs were different. Predicted wear rate (1.77 mg/million cycles was very close to experimental wear rate (1.84 mg/million cycles after testing in an AMTI knee wear simulator. Finite element analysis can predict experimental wear and may reduce the cost and time of preclinical testing.

  13. Split ring floating air riding seal for a turbine

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Jacob A

    2015-11-03

    A floating air riding seal for a gas turbine engine with a rotor and a stator, an annular piston chamber with an axial moveable annular piston assembly within the annular piston chamber, an annular cavity formed on the annular piston assembly that faces a seal surface on the rotor, and a central passage connecting the annular cavity to the annular piston chamber to supply compressed air to the seal face, where the annular piston assembly is a split piston assembly to maintain a tight seal as coning of the rotor disk occurs.

  14. Resource-saving technology for manufacturing billets for piston’s rings

    Directory of Open Access Journals (Sweden)

    A. N. Krutilin

    2010-10-01

    Full Text Available Piston’s rings are one of the most critical parts of heavy-duty engines for wear-work in conditions of prolonged exposure of alternating loads and high temperatures. Currently in the world production of billets for piston’s rings is dominated by the two methods of casting: production of individual and oiling billets of gray and ductile cast iron in green-sand mold and shell mold and centrifugal casting method (intended primarily for oiling billets of ductile iron; the technology for individual production billets for piston’s rings with a diameter up to 250 mm, from 250 to 450 mm with individual and oiling ways, over 450 mm - preference of oiling billet. The best parameters of physical-mechanical and operational characteristics piston’s rings are in the case of manufacture of billets to the maximum extent approaching the configuration to the finished product. The rings made of shaped billets are characterized by uniform distribution of properties from the perimeter, provide a given diagram of pressures and full fit to the cylinder. Because of deficiencies of traditional methods of casting, continuous quality requirements for billets, the need for economy of material, fuel and energy resources, are finding new progressive technological processes of production of high-quality billets for piston’s rings. One of the most promising for piston rings billet is a method of casting consists of immersing the sand molds into the melt. It is interesting idea, expressed by A. Sutherland and subsequently patented in several countries in the way of casting method, called "immersion pouring technology" (ICT-Immersion Casting Technique [1]. Experiments, conducted in the laboratory of the Belarusian National Technical University, have identified significant shortcomings of immersion method of casting. When forms are immersing, have an intensive gassing in molten metal, and freezing of the metal on the out surface of the form. But despite some

  15. Saturn's largest ring.

    Science.gov (United States)

    Verbiscer, Anne J; Skrutskie, Michael F; Hamilton, Douglas P

    2009-10-22

    Most planetary rings in the Solar System lie within a few radii of their host body, because at these distances gravitational accelerations inhibit satellite formation. The best known exceptions are Jupiter's gossamer rings and Saturn's E ring, broad sheets of dust that extend outward until they fade from view at five to ten planetary radii. Source satellites continuously supply the dust, which is subsequently lost in collisions or by radial transport. Here we report that Saturn has an enormous ring associated with its outer moon Phoebe, extending from at least 128R(S) to 207R(S) (Saturn's radius R(S) is 60,330 km). The ring's vertical thickness of 40R(S) matches the range of vertical motion of Phoebe along its orbit. Dynamical considerations argue that these ring particles span the Saturnian system from the main rings to the edges of interplanetary space. The ring's normal optical depth of approximately 2 x 10(-8) is comparable to that of Jupiter's faintest gossamer ring, although its particle number density is several hundred times smaller. Repeated impacts on Phoebe, from both interplanetary and circumplanetary particle populations, probably keep the ring populated with material. Ring particles smaller than centimetres in size slowly migrate inward and many of them ultimately strike the dark leading face of Iapetus.

  16. Prediction of wear rates in comminution equipment

    DEFF Research Database (Denmark)

    Jensen, Lucas Roald Dörig; Fundal, Erling; Møller, Per

    2010-01-01

    Raw material comminution equipment may be exposed to excessive wear, which makes it difficult to operate minerals processing plants continuously because lengthy and unplanned shut-downs interrupt the overall process. In general, most comminution equipment is fine-tuned to operate at low vibrations......-resistant high chromium white cast iron (21988/JN/HBW555XCr21), a heat-treated wear resistant steel (Hardox 400) and a plain carbon construction steel (S235). Quartz, which accounts for the largest wear loss in the cement industry, was chosen as abrasive. Other process parameters such as velocity (1–7 m...

  17. The contraceptive vaginal ring.

    Science.gov (United States)

    Edwardson, Jill; Jamshidi, Roxanne

    2010-03-01

    The contraceptive vaginal ring offers effective contraception that is self-administered, requires less frequent dosing than many other forms of contraception, and provides low doses of hormones. NuvaRing (Organon, Oss, The Netherlands), the only contraceptive vaginal ring approved for use in the United States, contains etonogestrel and ethinyl estradiol. It is inserted into the vagina for 3 weeks, followed by a 1-week ring-free period, and works by inhibiting ovulation. Most women note a beneficial effect on bleeding profiles and are satisfied with NuvaRing. Commonly reported adverse events include vaginitis, leukorrhea, headaches, and device-related events such as discomfort. Serious adverse events are rare. In Chile and Peru, progesterone-only vaginal contraceptive rings are available for nursing women. Studies are ongoing examining new formulations of vaginal contraceptive rings.

  18. New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring

    Energy Technology Data Exchange (ETDEWEB)

    de Pater, I; Hammel, H B; Gibbard, S G; Showalter, M R

    2006-02-02

    We compare near-infrared observations of the recently discovered outer rings of Uranus with HST results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced via impacts into the embedded moon Mab, which apparently orbits at a location where non-gravitational perturbations favor the survival and spreading of sub-micron sized dust. R/2003 U 2 more closely resembles Saturn's G ring.

  19. Certain near-rings are rings, II

    Directory of Open Access Journals (Sweden)

    Howard E. Bell

    1986-01-01

    Full Text Available We investigate distributively-generated near-rings R which satisfy one of the following conditions: (i for each x,y∈R, there exist positive integers m, n for which xy=ymxn; (ii for each x,y∈R, there exists a positive integer n such that xy=(yxn. Under appropriate additional hypotheses, we prove that R must be a commutative ring.

  20. Rubber Piston Membrane Model for Pneumatic Braking based on ANN-FEM%基于FEM-ANN法的气动刹车橡胶活塞膜设计模型

    Institute of Scientific and Technical Information of China (English)

    陈培文

    2015-01-01

    In this paper,artificial neural network(ANN)-finite element metho (FEM) model of rubber piston membrane to work out a pneumatic braking device based on Traincgf algorithm were established.In this model,the thickness of the rubber piston membrane of the pneumatic braking device was T,radius of the central ring was R,the fillet radius was R1 and fillet radius was R2,the output was stress analysis for the rubber piston membrane of the pneumatic braking device and network framework was considered to be 4-6-1.The final relative errors (RE) was 9.225%. As for optimal parameters for the rubber piston membrane of the pneumatic braking device the thickness was 8 mm,R1 was 6 mm,R2 was 18 mm and the greatest tolerant pressure was 4.83 MPa.%基于Traincgf算法建立了建立气动刹车装置橡胶活塞膜的神经网络(ANN)-有限元(FEM)设计模型。气动刹车装置橡胶活塞膜的厚度T,中心环半径R,倒圆角半径R1,倒圆角半径R2;输出层为气动刹车装置橡胶活塞膜应力分析。网络模型结构为4-6-1。最终测试相对误差(RE)为9.225%。气动刹车橡胶活塞膜设计的最佳参数为厚度T为8mm,倒角R1为6mm,倒角R2为18mm,可承受的压力最大为4.83MPa。

  1. Design and construction of the X-2 two-stage free piston driven expansion tube

    Science.gov (United States)

    Doolan, Con

    1995-01-01

    This report outlines the design and construction of the X-2 two-stage free piston driven expansion tube. The project has completed its construction phase and the facility has been installed in the new impulsive research laboratory where commissioning is about to take place. The X-2 uses a unique, two-stage driver design which allows a more compact and lower overall cost free piston compressor. The new facility has been constructed in order to examine the performance envelope of the two-stage driver and how well it couple to sub-orbital and super-orbital expansion tubes. Data obtained from these experiments will be used for the design of a much larger facility, X-3, utilizing the same free piston driver concept.

  2. Efficiency of a new internal combustion engine concept with variable piston motion

    Directory of Open Access Journals (Sweden)

    Dorić Jovan Ž.

    2014-01-01

    Full Text Available This paper presents simulation of working process in a new IC engine concept. The main feature of this new IC engine concept is the realization of variable movement of the piston. With this unconventional piston movement it is easy to provide variable compression ratio, variable displacement and combustion during constant volume. These advantages over standard piston mechanism are achieved through synthesis of the two pairs of non-circular gears. Presented mechanism is designed to obtain a specific motion law which provides better fuel consumption of IC engines. For this paper Ricardo/WAVE software was used, which provides a fully integrated treatment of time-dependent fluid dynamics and thermodynamics by means of onedimensional formulation. The results obtained herein include the efficiency characteristic of this new heat engine concept. The results show that combustion during constant volume, variable compression ratio and variable displacement have significant impact on improvement of fuel consumption.

  3. A new sliding joint to accommodate recoil of a free-piston-driven expansion tube facility

    Science.gov (United States)

    Gildfind, D. E.; Morgan, R. G.

    2016-11-01

    This paper describes a new device to decouple free-piston driver recoil and its associated mechanical vibration from the acceleration tube and test section of The University of Queensland's X3 expansion tube. A sliding joint is introduced to the acceleration tube which axially decouples the facility at this station. When the facility is fired, the upstream section of the facility, which includes the free-piston driver, can recoil upstream freely. The downstream acceleration tube remains stationary. This arrangement provides two important benefits. Firstly, it eliminates nozzle movement relative to the test section before and during the experiment. This has benefits in terms of experimental setup and alignment. Secondly, it prevents transmission of mechanical disturbances from the free-piston driver to the acceleration tube, thereby eliminating mechanically-induced transducer noise in the sensitive pressure transducers installed in this low-pressure tube. This paper details the new design, and presents experimental confirmation of its performance.

  4. Piston surface heat transfer during combustion in large marine diesel engines

    DEFF Research Database (Denmark)

    Jensen, Michael Vincent; Walther, Jens Honore

    2010-01-01

    limited. The numerical investigation focused on the simulation of a hot turbulent gas jet impinging on a wall under very high pressure, thus approximating the process of the actual impingement of hot combustion gasses on the piston surface during combustion. The surface heat flux at the wall......In the design process of large marine diesel engines information on the maximum heat load on the piston surface experienced during the engine cycle is an important parameter. The peak heat load occurs during combustion when hot combustion products impinge on the piston surface. Although the maximum...... instrumentation and high engine running costs compared to automotive engines. Therefore the investigation in this work was carried out numerically with the use of a computational fluid dynamics (CFD) code. At the same time, numerical work on detailed in-cylinder wall heat transfer in engines has been quite...

  5. Final design of a free-piston hydraulic advanced Stirling conversion system

    Science.gov (United States)

    Wallace, D. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.

    1991-01-01

    Under the US Department of Energy's (DOEs) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for solar distributed receiver systems. The final design is described of an engineering prototype advanced Stirling conversion system (ASCS) with a free-piston hydraulic engine output capable of delivering about 25 kW of electric power to a utility grid. The free-piston Stirling engine has the potential for a highly reliable engine with long life because it has only a few moving parts, has noncontacting bearings, and can be hermetically sealed. The ASCS is designed to deliver maximum power per year over a range of solar input with a design life of 30 years (60,000 h). The system includes a liquid Nak pool boiler heat transport system and a free-piston Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator.

  6. Analysis of a system modelling the motion of a piston in a viscous gas

    Science.gov (United States)

    Maity, Debayan; Takahashi, Takéo; Tucsnak, Marius

    2016-09-01

    We study a free boundary problem modelling the motion of a piston in a viscous gas. The gas-piston system fills a cylinder with fixed extremities, which possibly allow gas from the exterior to penetrate inside the cylinder. The gas is modeled by the 1D compressible Navier-Stokes system and the piston motion is described by the second Newton's law. We prove the existence and uniqueness of global in time strong solutions. The main novelty brought in by our results is that they include the case of nonhomogeneous boundary conditions which, as far as we know, have not been studied in this context. Moreover, even for homogeneous boundary conditions, our results require less regularity of the initial data than those obtained in previous works.

  7. Flat mirror tilt and piston measurement based on structured light reflection.

    Science.gov (United States)

    Li, Lulu; Zhao, Wenchuan; Wu, Fan; Liu, Yong

    2014-11-03

    This paper presents a simple method for flat mirror tilt and piston measurement. The method only needs an LCD screen and a CCD camera. LCD screen displays structured light pattern, and camera takes the pattern's virtual image (VI) reflected by the mirror. Pose relationship between camera coordinate system and VI coordinate system can be calculated by camera calibration. Through coordinate transition, the relative tilt and piston of the mirror can be obtained. This method is simple in both structure and principle, and experiments prove that it can measure the flat mirror tilt for about 1″ accuracy and piston for less than 1um accuracy. And under the guidance of our method, a mirror can be adjusted to a specified pose.

  8. Investigation into Piston-Slap Force under Friction and Connecting Rod Effects of Diesel Engine

    Directory of Open Access Journals (Sweden)

    Fuadi Noor Balia

    2011-01-01

    Full Text Available In this paper, a dynamics analysis of diesel engine through investigation of the piston-slap force by considering the friction and connecting rod effects is presented. A single-cylinder of 500 cc Diesel Engine’s mechanism was examined. The position, velocity and acceleration of the pins and the center of mass for each linkage were calculated by using vector analysis principles. The governing equations of the forces and moments were derived based on the Cartesian coordinate principles, and solved by using Gauss elimination method. Hence, the piston-slap force onto the cylinder wall under friction and connecting rod effects were determined. Favourable comparison with previously published work was performed and excellent agreement between the results was obtained. The result shows that the friction and connecting rod effects significantly influence to the piston-slap force.

  9. The predictive analysis of wear work-rates in wear test rigs

    Energy Technology Data Exchange (ETDEWEB)

    Phalippou, C.; Delaune, X.

    1996-12-31

    Impact and sliding wear in components is classically studied, as far as the wear laws are concerned, in specific wear test rigs that simulate the vibratory motion induced by the flow. In this paper, an experimental and numerical study on the impact forces and wear work-rates of a typical AECL rig is presented. The mode shapes and frequencies are measured and compared with finite element computations. Impact and sliding motions between the wear specimens are calculated and compared to the experimental results. Impact forces, mean values of wear work-rates as well as the specimen relative motions are found to be close to the experimental data. (authors). 14 refs., 9 figs., 5 tabs.

  10. On Exchange QB∞-Rings

    Institute of Scientific and Technical Information of China (English)

    Huanyin Chen

    2007-01-01

    In this paper, we introduce a new class of rings, the QB∞-rings. We investigate necessary and sufficient conditions under which an exchange ring is a QB∞-ring. The modules over an exchange QB∞-ring are studied. Also, we prove that every regular square matrix over an exchange QB∞-ring admits a diagonal reduction by pseudo-invertible matrices.

  11. Neutrosophic LA-Semigroup Rings

    Directory of Open Access Journals (Sweden)

    Mumtaz Ali

    2015-01-01

    Full Text Available Neutrosophic LA-semigroup is a midway structure between a neutrosophic groupoid and a commutative neutrosophic semigroup. Rings are the old concept in algebraic structures. We combine the neutrosophic LA-semigroup and ring together to form the notion of neutrosophic LA-semigroup ring. Neutrosophic LAsemigroup ring is defined analogously to neutrosophic group ring and neutrosophic semigroup ring.

  12. Design of an interferometric system for piston measurements in segmented primary mirrors

    Science.gov (United States)

    Arasa, Josep; Laguarta, Ferran; Pizarro, Carlos; Tomas, Nuria; Pinto, Agusti

    2000-10-01

    Recently, telescopes with segmented primary mirrors are becoming increasingly popular due to their ability of achieving large apertures without the inconveniences caused by the fabrication and handling of monolithic surfaces with 8m (or over) in diameter. The difference in position of each pair of adjacent segments along the local normal of their interface (called piston hereafter), however, needs to be precisely measured in order to provide a diffraction- limited image. If a system yielding the nanometric accuracy required in piston measurements worked in daylight hours, the resultant saving in observation time would be an important advance on a majority of the state-of-the-art piston measurement systems. An interferometric piston measurement instrument accomplishing such objectives has been designed starting from the usual Michelson configuration at the CD6 (Terrassa, Spain), and its final test has been carried out in the test workbench of the Instituto de Astrofisica de Canarias (IAC, Canary Islands, Spain). Its optical layout relies on projecting the reference arm of the interferometer onto one of the segments of the pair considered, along the direction of the local normal to the surface while the measurement arm is projected onto the interface which divides the pair of segments considered. The field of view and its illumination are calculated to be equivalent in both segments. The lateral shift of the fringes in both interferograms determines the piston error present. A combination of monochromatic and white light is used, in order to remove the (lambda) /2 phase ambiguities present in piston measurements without losing the required resolution in the measurement. In this paper, the optical design of this interferometric piston measurement instrument will be presented. The particular configuration used in the interferometer, the implementation of an imaging system allowing to see both the interface of the segments and the interference fringes, the effect of the

  13. A feasibility assessment of magnetic bearings for free-piston Stirling space power converters

    Energy Technology Data Exchange (ETDEWEB)

    Curwen, P.W.; Rao, D.K.; Wilson, D.S. [Mechanical Technology Inc., Latham, NY (United States)

    1992-06-01

    This report describes work performed by Mechanical Technology Incorporated (MTI) under NASA Contract NAS3-26061, {open_quotes}A Feasibility Assessment of Magnetic Bearings for Free-Piston Stirling Space Engines.{close_quotes} The work was performed over the period from July 1990 through August 1991. The objective of the effort was to assess the feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery of the type currently being evaluated for possible use in future long-term space missions.

  14. HPGR simulation from piston-die tests with an itabirite ore

    Directory of Open Access Journals (Sweden)

    Hakan Benzer

    Full Text Available Abstract The Minas Rio project, owned by Anglo American, has HPGRs in open circuit operated as a tertiary/quaternary crushing stage. Currently this type of equipment is designed from HPGR tests on laboratory scale and pilot scale tests. This paper presents a methodology for simulating HPGR from piston-die tests on laboratory scale and a mathematical model developed in Hacettepe University in Turkey. The parameters determined from the results of the piston-die tests were used to validate the HPGR testing on pilot scale. Finally, the model was used to predict the particle size distribution in the HPGR product on industrial scale.

  15. A transient tribodynamic approach for the calculation of internal combustion engine piston slap noise

    Science.gov (United States)

    Dolatabadi, N.; Littlefair, B.; De la Cruz, M.; Theodossiades, S.; Rothberg, S. J.; Rahnejat, H.

    2015-09-01

    An analytical/numerical methodology is presented to calculate the radiated noise due to internal combustion engine piston impacts on the cylinder liner through a film of lubricant. Both quasi-static and transient dynamic analyses coupled with impact elasto-hydrodynamics are reported. The local impact impedance is calculated, as well as the transferred energy onto the cylinder liner. The simulations are verified against experimental results for different engine operating conditions and for noise levels calculated in the vicinity of the engine block. Continuous wavelet signal processing is performed to identify the occurrence of piston slap noise events and their spectral content, showing good conformance between the predictions and experimentally acquired signals.

  16. STUDIES ON TOOL WEAR CONDITION MONITORING

    Directory of Open Access Journals (Sweden)

    Hüseyin Metin ERTUNÇ

    2001-01-01

    Full Text Available In this study, wear mechanisms on cutting tools, especially for the drill bits, during the cutting operation have been investigated. As the importance of full automation in industry has gained substantial importance, tool wear condition monitoring during the cutting operation has been the subject of many investigators. Tool condition monitoring is very crucial in order to change the tool before breakage. Because tool breakage can cause considerable economical damage to both the machine tool and workpiece. In this paper, the studies on the monitoring of drill bit wear in literature have been introduced; the direct/indirect techniques used and sensor fusion techniques have been summarized. The methods which were proposed to determine tool wear evolution as processing the sensor signals collected have been provided and their references have been given for detailed information.

  17. Separation of combustion noise and piston-slap in diesel engine—Part II: Separation of combustion noise and piston-slap using blind source separation methods

    Science.gov (United States)

    Servière, C.; Lacoume, J.-L.; El Badaoui, M.

    2005-11-01

    This paper is devoted to blind separation of combustion noise and piston-slap in diesel engines. The two phenomena are recovered only from signals issued from accelerometers placed on one of the cylinders. A blind source separation (BSS) method is developed, based on a convolutive model of non-stationary mixtures. We introduce a new method based on the joint diagonalisation of the time varying spectral matrices of the observation records and a new technique to handle the problem of permutation ambiguity in the frequency domain. This method is then applied to real data and the estimated sources are validated by several physical arguments. So, the contribution of the piston-slap and the combustion noise can be recovered for all the sensors. The energy of the two phenomena can then be given with regards to the position of the accelerometers.

  18. Effects of piston elastic deformation on piston secondary motion and skirt lubrication characteristics%活塞弹性变形对活塞二阶运动及裙部润滑特性的影响

    Institute of Scientific and Technical Information of China (English)

    阮登芳; 许金霞; 高鑫

    2015-01-01

    为揭示活塞弹性变形对活塞二阶运动及裙部润滑特性的影响规律,基于有限元法建立活塞和缸套的结构动力学模型,耦合活塞二阶运动方程及裙部流体动力润滑模型,分析活塞弹性对活塞二阶运动和裙部润滑特性的影响。结果表明:不同曲轴转角下活塞主、次推力面的变形不同,做功行程中变形明显,而且最大变形量出现的区域随曲轴转角的变化而改变;考虑活塞弹性变形后,活塞二阶运动一般比不考虑活塞弹性变形有所增加,在压缩和做功行程中增加明显;活塞裙部的最小油膜厚度增加,而总摩擦功耗降低,做功行程中两者变化明显;油膜压力场峰值出现位置及油膜压力分布规律改变,油膜压力场峰值减小。该研究为活塞裙部型线设计及配缸间隙选择提供参考。%Piston skirt-liner is one of the primary friction pairs influencing the friction power loss of an internal combustion engine, so it is feasible to improve the fuel economy of engines by studying the lubrication characteristics of the piston skirt-liner to reduce the friction power loss. The piston skirt lubrication is related to the piston secondary motion and the elastic deformation of the piston and liner, and there exists a strong coupled relationship between them. Therefore, it may be more reasonable to couple the elastic deformation equation of piston and liner than ignore the deformation of piston and liner, when the piston skirt lubrication and the piston secondary motion equations are solved. In order to reveal the effects of the piston elastic deformation on the piston secondary motion and skirt lubrication characteristics, the structural dynamics equations of the piston and liner were established based on the finite element modal reduction method, the piston secondary motion equation, the average Reynolds equation and the possible solid-to-solid contact equation in mixed lubrication

  19. Effect of La2O3 on electrical friction and wear properties of Cu-graphite composites

    Institute of Scientific and Technical Information of China (English)

    莫飞; 凤仪; 陈阳明; 王雨晴; 钱刚; 豆亚坤; 张学斌

    2015-01-01

    Sliding friction and wear experiments using Cu-La2O3-graphite composites against Cu-5 wt.%Ag alloy ring were con-ducted at a constant sliding speed of 10 m/s, a current density of 10 A/cm2 and a load of 2.5 N/cm2. These composites with different La2O3and graphite contents were fabricated by hot-pressing. Physical and mechanical properties of the composites were examined. Morphologies of the worn surface of composites were observed using optical microscopy. X-ray photoelectron spectroscopy spectra were used to study compositions of the lubricating film. The results showed that with the increasing addition of La2O3, hardness, flexural strength and electrical resistivity increased, but the relative density dropped. The friction coefficient increased with the in-creasing addition of La2O3. Composite containing 3 vol.% of La2O3 and 37 vol.% of graphite showed the best wear resistance. The main wear mechanisms of composites were abrasive wear, oxidative wear and adhesive wear.

  20. Wear behavior of austenite containing plate steels

    Science.gov (United States)

    Hensley, Christina E.

    As a follow up to Wolfram's Master of Science thesis, samples from the prior work were further investigated. Samples from four steel alloys were selected for investigation, namely AR400F, 9260, Hadfield, and 301 Stainless steels. AR400F is martensitic while the Hadfield and 301 stainless steels are austenitic. The 9260 exhibited a variety of hardness levels and retained austenite contents, achieved by heat treatments, including quench and tempering (Q&T) and quench and partitioning (Q&P). Samples worn by three wear tests, namely Dry Sand/Rubber Wheel (DSRW), impeller tumbler impact abrasion, and Bond abrasion, were examined by optical profilometry. The wear behaviors observed in topography maps were compared to the same in scanning electron microscopy micrographs and both were used to characterize the wear surfaces. Optical profilometry showed that the scratching abrasion present on the wear surface transitioned to gouging abrasion as impact conditions increased (i.e. from DSRW to impeller to Bond abrasion). Optical profilometry roughness measurements were also compared to sample hardness as well as normalized volume loss (NVL) results for each of the three wear tests. The steels displayed a relationship between roughness measurements and observed wear rates for all three categories of wear testing. Nanoindentation was used to investigate local hardness changes adjacent to the wear surface. DSRW samples generally did not exhibit significant work hardening. The austenitic materials exhibited significant hardening under the high impact conditions of the Bond abrasion wear test. Hardening in the Q&P materials was less pronounced. The Q&T microstructures also demonstrated some hardening. Scratch testing was performed on samples at three different loads, as a more systematic approach to determining the scratching abrasion behavior. Wear rates and scratch hardness were calculated from scratch testing results. Certain similarities between wear behavior in scratch testing

  1. A Study of Slipper and Rail Wear Interaction at Low Speed

    Science.gov (United States)

    2014-06-19

    taking care of the boys, a house and a dog and for not getting discouraged. I pray that they will learn as I have how important it is to ensure Yahovah...wear, delamination wear, seizure wear, melt wear, severe oxidational wear and adhesive wear. Adhesive wear comprised of three zones: low speed...model is experiencing seizure or melt wear, then something is wrong with the model. Lim and Ashby also published on their wear map the normalized wear

  2. A systematic review of the effect of piston diameter in stapes surgery for otosclerosis on hearing results

    NARCIS (Netherlands)

    Wegner, Inge; Verhagen, Jessica J; Stegeman, Inge; Vincent, Robert; Grolman, Wilko

    2015-01-01

    OBJECTIVE: To evaluate the effect of piston diameter in primary stapedotomy for otosclerosis patients measured by hearing outcome. DATA SOURCES: PubMed, Embase, and the Cochrane Library. REVIEW METHODS: A systematic search was conducted. Studies reporting original data on the effect of piston diamet

  3. A systematic review of the effect of piston diameter in stapes surgery for otosclerosis on hearing results

    NARCIS (Netherlands)

    Wegner, Inge; Verhagen, Jessica J; Stegeman, Inge; Vincent, Robert; Grolman, Wilko

    2015-01-01

    OBJECTIVE: To evaluate the effect of piston diameter in primary stapedotomy for otosclerosis patients measured by hearing outcome. DATA SOURCES: PubMed, Embase, and the Cochrane Library. REVIEW METHODS: A systematic search was conducted. Studies reporting original data on the effect of piston

  4. Third abrasive wear mode: is it possible?

    Directory of Open Access Journals (Sweden)

    Ronaldo Câmara Cozza

    2014-04-01

    Full Text Available The objective of this paper is to propose an initial discussion on the characterization of a third abrasive wear mode. The results obtained in a previous work [1] under different test conditions revealed the occurrence of the superposition of the “rolling” and “grooving” abrasive wear modes. This phenomenon was denoted “micro-rolling abrasion” due to the observation that “rolling abrasion” was found to act on “grooving abrasion”.

  5. Biotribology :articular cartilage friction, wear, and lubrication

    OpenAIRE

    Schroeder, Matthew O

    1995-01-01

    This study developed, explored, and refined techniques for the in vitro study of cartilage-on-cartilage friction, deformation, and wear. Preliminary results of in vitro cartilage-on- cartilage experiments with emphasis on wear and biochemistry are presented. Cartilage-bone specimens were obtained from the stifle joints of steers from a separate controlled study. The load, sliding speed, and traverse of the lower specimens were held constant as lubricant and test length were varied. Lubric...

  6. Pseudomembranous candidiasis in patient wearing full denture

    Directory of Open Access Journals (Sweden)

    Nurdiana Nurdiana

    2009-06-01

    Full Text Available Background: Oral candidiasis is a common opportunistic infection of the oral cavity caused by an overgrowth of Candida species, the commonest being Candida albicans. Candida albicans is a harmless commensal organism inhabiting the mouths but it can change into pathogen and invade tissue and cause acute and chronic disease. Dentures predispose to infection with Candida in as many as 65% of elderly people wearing full upper dentures. Purpose: The purpose of this case report is to discuss thrush in patient wearing full denture which rapidly developed. Case: This paper report a case of 57 year-old man who came to the Oral Medicine Clinic Faculty of Dentistry Airlangga University with clinical appearance of pseudomembranous candidiasis (thrush. Case Management: Diagnosis of this case is confirmed with microbiology examination. Patient was wearing full upper dentures, and from anamnesis known that patient wearing denture for 24 hours and he had poor oral hygiene. Patient was treated with topical (nystatin oral suspension and miconazole oral gel and systemic (ketoconazole antifungal. Patient also instructed not to wear his denture and cleaned white pseudomembrane on his mouth with soft toothbrush. Conclusion: Denture, habit of wearing denture for 24 hours, and poor oral hygiene are predisposing factors of thrush and it can healed completely after treated with topical and systemic antifungal.

  7. Influence of the skin effect in a rail gun on the parameters of the moving plasma piston

    Science.gov (United States)

    Iuferev, V. S.; Gnedina, M. L.; Gnedin, N. Iu.

    1992-01-01

    The problem of the motion of the plasma piston in a rail gun launcher is solved with allowance for the skin effect using plane geometry and the quasi-stationary approximation. The temperature along the piston is assumed to be constant, and the piston is assumed to move as a whole at a velocity equal to that of the accelerated projectile. It is shown that current displacement toward the rear of the piston due to the skin effect leads to an increase in the gasdynamic pressure in the plasma, with a resulting reduction in the extension of the plasmoid. The latter effect is particularly pronounced when the mass of the plasma exceeds that of the piston.

  8. Development of a model capable of predicting the performance of piston ring-cylinder liner-like tribological interfaces

    DEFF Research Database (Denmark)

    Felter, C.L.; Vølund, A.; Imran, Tajammal

    2010-01-01

    on a measured temperature only; thus, it is not necessary to include the energy equation. Conservation of oil is ensured throughout the domain by considering the amount of oil outside the lubricated interface. A model for hard contact through asperities is also included. Second, a laboratory-scale test rig....... The work described in this article addresses the subject from both an experimental and a theoretical perspective. First, a one-dimensional numerical model based on the Reynolds equation is presented. It uses a pressure-density relation for the modelling of cavitation. The viscosity is assumed to depend...

  9. Gulf ring algae

    Science.gov (United States)

    Although they rank among the tiniest of the microspcopic phytoplankton, coccolithophore algae aid oceanographers studying the Gulf Stream rings and the ring boundaries. The algal group could help to identify more precisely the boundary of the warm rings of water that spin off from the Gulf Stream and become independent pools of warm water in the colder waters along the northeastern U.S. coast.Coccolithophore populations in the Gulf Stream rings intrigue oceanographers for two reasons: The phytoplankton are subjected to an environment that changes every few days, and population explosions within one coccolithophore species seem to be associated with changes in the characteristics of ocean water, said Pat Blackwelder, an associate professor at the Nova Oceanographic Center in Dania, Fla. She is one of many studying the physics, chemistry, and biology of warm core rings. A special oceanography session on these rings was held at the recent AGU Fall Meeting/ASLO Winter Meeting.

  10. Token Ring Project

    Directory of Open Access Journals (Sweden)

    Adela Ionescu

    2007-01-01

    Full Text Available Ring topology is a simple configuration used to connect processes that communicate among themselves. A number of network standards such as token ring, token bus, and FDDI are based on the ring connectivity. This article will develop an implementation of a ring of processes that communicate among themselves via pipe links. The processes are nodes in the ring. Each process reads from its standard input and writes in its standard output. N-1 process redirects the its standard output to a standard input of the process through a pipe. When the ring-structure is designed, the project can be extended to simulate networks or to implement algorithms for mutual exclusion

  11. Dusty plasma (Yukawa) rings

    CERN Document Server

    Sheridan, T E

    2010-01-01

    One-dimensional and quasi-one-dimensional strongly-coupled dusty plasma rings have been created experimentally. Longitudinal (acoustic) and transverse (optical) dispersion relations for the 1-ring were measured and found to be in very good agreement with the theory for an unbounded straight chain of particles interacting through a Yukawa (i.e., screened Coulomb or Debye-H\\"uckel) potential. These rings provide a new system in which to study one-dimensional and quasi-one-dimensional physics.

  12. Token ring technology report

    CERN Document Server

    2013-01-01

    Please note this is a Short Discount publication. This report provides an overview of the IBM Token-Ring technology and products built by IBM and compatible vendors. It consists of two sections: 1. A summary of the design trade-offs for the IBM Token-Ring. 2. A summary of the products of the major token-ring compatible vendors broken down by adapters and components, wiring systems, testing, and new chip technology.

  13. Wear Property of Cast Steel Wheel Material in Rail Truck

    Institute of Scientific and Technical Information of China (English)

    MI Guo-fa; LIU Yan-lei; ZHANG Bin; FU Xiu-qin; ZHANG Hong; SONG Guo-xiang

    2009-01-01

    Wear property of material plays a key role in the service time of workpiece.A major objective in the development of new wheel materials is to improve the wear performance.The wear property of B and B+ grade cast steel materials was reported.The results showed that B+ grade cast steel material exhibited better wear property than the B grade material.Carbon content related to the hardness match was the principal factor affecting the wear properties.

  14. Wear-resistance of Aluminum Matrix Microcomposite Materials

    Directory of Open Access Journals (Sweden)

    M. Kandeva

    2011-03-01

    Full Text Available A procedure is developed for the study of wear of aluminum alloys AlSi7 obtained by casting, reinforced by TiC microparticles, before and after heat treatment. Tribological study is realized under conditions of friction on counterbody with fixed abrasive. Experimental results were obtained for mass wear, wear rate, wear intensity and wear-resistance of the alloys with different wt% of microparticles.

  15. On -Coherent Endomorphism Rings

    Indian Academy of Sciences (India)

    Li-Xin Mao

    2008-11-01

    A ring is called right -coherent if every principal right ideal is finitely presented. Let $M_R$ be a right -module. We study the -coherence of the endomorphism ring of $M_R$. It is shown that is a right -coherent ring if and only if every endomorphism of $M_R$ has a pseudokernel in add $M_R; S$ is a left -coherent ring if and only if every endomorphism of $M_R$ has a pseudocokernel in add $M_R$. Some applications are given.

  16. Physics of quantum rings

    Energy Technology Data Exchange (ETDEWEB)

    Fomin, Vladimir M. (ed.) [Leibniz Institute for Solid State and Materials Research, Dresden (Germany)

    2014-07-01

    Presents the new class of materials of quantum rings. Provides an elemental basis for low-cost high-performance devices promising for electronics, optoelectronics, spintronics and quantum information processing. Explains the physical properties of quantum rings to cover a gap in scientific literature. Presents the application of most advanced nanoengineering and nanocharacterization techniques. This book deals with a new class of materials, quantum rings. Innovative recent advances in experimental and theoretical physics of quantum rings are based on the most advanced state-of-the-art fabrication and characterization techniques as well as theoretical methods. The experimental efforts allow to obtain a new class of semiconductor quantum rings formed by capping self-organized quantum dots grown by molecular beam epitaxy. Novel optical and magnetic properties of quantum rings are associated with non-trivial topologies at the nanoscale. An adequate characterization of quantum rings is possible on the basis of modern characterization methods of nanostructures, such as Scanning Tunneling Microscopy. A high level of complexity is demonstrated to be needed for a dedicated theoretical model to adequately represent the specific features of quantum rings. The findings presented in this book contribute to develop low-cost high-performance electronic, spintronic, optoelectronic and information processing devices based on quantum rings.

  17. A rolling-gliding wear simulator for the investigation of tribological material pairings for application in total knee arthroplasty

    Directory of Open Access Journals (Sweden)

    Denkena Berend

    2010-06-01

    Full Text Available Abstract Background Material wear testing is an important technique in the development and evaluation of materials for use in implant for total knee arthroplasty. Since a knee joint induces a complex rolling-gliding movement, standardised material wear testing devices such as Pin-on-Disc or Ring-on-Disc testers are suitable to only a limited extent because they generate pure gliding motion only. Methods A rolling-gliding wear simulator was thus designed, constructed and implemented, which simulates and reproduces the rolling-gliding movement and loading of the knee joint on specimens of simplified geometry. The technical concept was to run a base-plate, representing the tibia plateau, against a pivoted cylindrical counter-body, representing one femur condyle under an axial load. A rolling movement occurs as a result of the friction and pure gliding is induced by limiting the rotation of the cylindrical counter-body. The set up also enables simplified specimens handling and removal for gravimetrical wear measurements. Long-term wear tests and gravimetrical wear measurements were carried out on the well known material pairings: cobalt chrome-polyethylene, ceramic-polyethylene and ceramic-ceramic, over three million motion cycles to allow material comparisons to be made. Results The observed differences in wear rates between cobalt-chrome on polyethylene and ceramic on polyethylene pairings were similar to the differences of published data for existing material-pairings. Test results on ceramic-ceramic pairings of different frontal-plane geometry and surface roughness displayed low wear rates and no fracture failures. Conclusions The presented set up is able to simulate the rolling-gliding movement of the knee joint, is easy to use, and requires a minimum of user intervention or monitoring. It is suitable for long-term testing, and therefore a useful tool for the investigation of new and promising materials which are of interest for application in

  18. An effective sensor for tool wear monitoring in face milling: Acoustic emission

    Indian Academy of Sciences (India)

    M T Mathew; P Srinivasa Pai; L A Rocha

    2008-06-01

    Acoustic Emission (AE) has been widely used for monitoring manufacturing processes particularly those involving metal cutting. Monitoring the condition of the cutting tool in the machining process is very important since tool condition will affect the part size, quality and an unexpected tool failure may damage the tool, work-piece and sometimes the machine tool itself. AE can be effectively used for tool condition monitoring applications because the emissions from process changes like tool wear, chip formation i.e. plastic deformation, etc. can be directly related to the mechanics of the process. Also AE can very effectively respond to changes like tool fracture, tool chipping, etc. when compared to cutting force and since the frequency range is much higher than that of machine vibrations and environmental noises, a relatively uncontaminated signal can be obtained. AE signal analysis was applied for sensing tool wear in face milling operations. Cutting tests were carried out on a vertical milling machine. Tests were carried out for a given cutting condition, using single insert, two inserts (adjacent and opposite) and three inserts in the cutter. AE signal parameters like ring down count and rms voltage were measured and were correlated with flank wear values (VB max). The results of this investigation indicate that AE can be effectively used for monitoring tool wear in face milling operations.

  19. The Development of a Control System for a 5 Kilowatt Free Piston Stirling Engine Convertor

    Science.gov (United States)

    Kirby, Raymond L.; Vitale, Nick

    2008-01-01

    The new NASA Vision for Exploration, announced by President Bush in January 2004, proposes an ambitious program that plans to return astronauts to the moon by the 2018 time frame. A recent NASA study entitled "Affordable Fission Surface Power Study" recommended a 40 kWe, 900 K, NaK-cooled, Stirling convertors for 2020 launch. Use of two of the nominal 5 kW convertors allows the system to be dynamically balanced. A group of four dual-convertor combinations that would yield 40 kWe can be tested to validate the viability of Stirling technology for space fission surface power systems. The work described in this paper deals specifically with the control system for the 5 kW convertor described in the preceding paragraph. This control system is responsible for maintaining piston stroke to a setpoint in the presence of various disturbances including electrical load variations. Pulse starting of the Free Piston Stirling Engine (FPSE) convertor is also an inherent part of such a control system. Finally, the ability to throttle the engine to match the required output power is discussed in terms of setpoint control. Several novel ideas have been incorporated into the piston stroke control strategy that will engender a stable response to disturbances in the presence of midpoint drift while providing useful data regarding the position of both the power piston and displacer.

  20. Influence of piston position on the scavenging and swirling flow in two-stoke diesel engines

    DEFF Research Database (Denmark)

    Obeidat, Anas; Haider, Sajjad; Meyer, Knud Erik

    2011-01-01

    We study the eect of piston position on the in-cylinder swirling flow in a low speed large two-stroke marine diesel engine model. We are using Large Eddy Simulations in OpenFOAM, with three different models for the turbulent flow: a one equation model (OEM), a dynamic one equation model (DOEM...

  1. Stochastic stability assessment of a semi-free piston engine generator concept

    Science.gov (United States)

    Kigezi, T. N.; Gonzalez Anaya, J. A.; Dunne, J. F.

    2016-09-01

    Small engines, as power generators with low-noise and vibration characteristics, are needed in two niche application areas: as electric vehicle range extenders and as domestic micro Combined Heat and Power systems. A recent semi-free piston design known as the AMOCATIC generator fully meets this requirement. The engine potentially allows for high energy conversion efficiencies at resonance derived from having a mass and spring assembly. As with free-piston engines in general, stability and control of piston motion has been cited as the prime challenge limiting the technology's widespread application. Using physical principles, we derive in this paper two important results: an energy balance criterion and a related general stability criterion for a semi-free piston engine. Control is achieved by systematically designing a Proportional Integral (PI) controller using a control-oriented engine model for which a specific stability condition is stated. All results are presented in closed form throughout the paper. Simulation results under stochastic pressure conditions show that the proposed energy balance, stability criterion, and PI controller, operate as predicted to yield stable engine operation at fixed compression ratio.

  2. A 1987 overview of free-piston Stirling technology for space power application

    Science.gov (United States)

    Slaby, Jack G.; Alger, Donald L.

    1987-01-01

    An overview is presented of the NASA Lewis Research Center free-piston Stirling engine activities directed toward space-power application. NASA Lewis serves as the project office to manage the newly initiated NASA SP-100 Advanced Technology Program. One of the major elements of this five-year program is the development of advanced power conversion concepts of which the Stirling cycle is a viable growth candidate. Under this program the status of the 25 kWe opposed-piston Space Power Demonstrator Engine (SPDE) is presented. Included in the SPDE discussion are comparisons between predicted and experimental engine performance, enhanced performance resulting from regenerator modification, increased operating stroke brought about by isolating the gas bearing flow between the displacer and power piston, identifying excessive energy losses and recommending corrective action, and a better understanding of linear alternator design and operation. Technology work is also conducted on heat exchanger concepts, both design and fabrication. Design parameters and conceptual design features are also presented for a 25 kWe, single-cylinder free-piston Stirling space-power converter.

  3. The Atmospheric piston simulator as an integral part of the calibration unit of LINC - NIRVANA

    Science.gov (United States)

    Follert, R.; Herbst, T. M.; Bizenberger, P.; DeBonis, F.

    2010-07-01

    The atmospheric piston simulator is an integral part of the calibration unit of LINC-NIRVANA, the Fizeau interferometric imager for the Large Binocular Telescope. The calibration unit will be necessary to align and set up the different opto - mechanical subsystems of the instrument. It will assist in (1) the alignment of the optics via reference fibers; (2) establishing zero optical path difference using a balanced fiber splitter; (3) flat fielding of the detectors with an integrating sphere; (4) correction of the non-common path aberrations using a fiber-based phase diversity source; and (5) calibration of the adaptive optics with a rotating reference fiber plate. Substantial testing and verification of the fringe tracker under as realistic as possible conditions in the lab is desirable, since the performance of the fringe tracker will ultimately determine the high angular resolution imaging capability of LINC-NIRVANA as a whole. We are therefore also constructing an atmospheric piston simulator working in the J and H photometric bands. As with many of the other calibration unit sub-systems, our design concept is mainly fiber based. Opto - electronic phase modulators will be used to introduce the piston sequences. The control system of the piston modulators will allow for easy implementation of different vibration power spectra. This will enable us to test and demonstrate the capabilities of the fringe tracker under realistic conditions.

  4. Design and Fabrication of a 5-kWe Free-Piston Stirling Power Conversion System

    Science.gov (United States)

    Chapman, Peter A.; Walter, Thomas J.; Brandhorst, Henry W., Jr.

    2008-01-01

    Progress in the design and fabrication of a 5-kWe free-piston Stirling power conversion system is described. A scaled-down version of the successful 12.5-kWe Component Test Power Converter (CTPC) developed under NAS3-25463, this single cylinder prototype incorporates cost effective and readily available materials (steel versus beryllium) and components (a commercial linear alternator). The design consists of a displacer suspended on internally pumped gas bearings and a power piston/alternator supported on flexures. Non-contacting clearance seals are used between internal volumes. Heat to and from the prototype is supplied via pumped liquid loops passing through shell and tube heat exchangers. The control system incorporates several novel ideas such as a pulse start capability and a piston stroke set point control strategy that provides the ability to throttle the engine to match the required output power. It also ensures stable response to various disturbances such as electrical load variations while providing useful data regarding the position of both power piston and displacer. All design and analysis activities are complete and fabrication is underway. Prototype test is planned for summer 2008 at Foster-Miller to characterize the dynamics and steady-state operation of the prototype and determine maximum power output and system efficiency. Further tests will then be performed at Auburn University to determine start-up and shutdown characteristics and assess transient response to temperature and load variations.

  5. Avco Lycoming/NASA contract status. [on reduction of emissions from aircraft piston engines

    Science.gov (United States)

    Duke, L. C.

    1976-01-01

    The standards promulgated by the Environmental Protection Agency (EPA) for carbon monoxide (CO), unburned hydrocarbon (HC), and oxides-of-nitrogen (NOx) emissions were the basis in a study of ways to reduce emissions from aircraft piston engines. A variable valve timing system, ultrasonic fuel atomization, and ignition system changes were postulated.

  6. Diseño de un sujetador rápido para mecanizado de pistones

    OpenAIRE

    Di Giusto, Marco Agustín.

    2013-01-01

    Proyecto Integrador (II)--FCEFN-UNC, 2013 Trata el estudio de una solución de automatización de una célula de fabricación, con el objetivo de aumentar la productividad y la competitividad de Pistones Persan, fabricante de partes de motor ubicado en Córdoba

  7. Investigation into piston-slap-induced vibration for engine condition simulation and monitoring

    Science.gov (United States)

    Geng, Z.; Chen, J.

    2005-04-01

    Piston slap is a common impact phenomenon existing in the reciprocating engine. It is also a major cause of the complex transient vibration response related to the impact excitation inside the engine. In order to correlate the piston-slap impact with the slap-induced vibration and consequently find out an effective approach for the engine dynamic behaviour simulation and working condition monitoring, an in-depth investigation from theoretical modelling to experimental verification is made in this paper. Firstly, the piston-slap phenomenon inside the reciprocating engine is briefly discussed from the viewpoint of engine mechanics. Based upon this, a nonlinear model is developed to simulate the slap-induced vibration response. Using numerical integration procedure, the slap-induced vibration response and its correlation with the inner-cylinder piston-slap impact are reasonably evaluated. Guided by the simulating results and, by introducing a fast wavelet-packet decomposition and reconstruction algorithm, a specially designed experiment is made to practically measure and extract the slap-induced impact message inside the 6190Z LC diesel engine. Comparison between the simulation and practically measured and reconstructed engine vibration signals verifies the effectiveness and practicality of this approach for more detailed academic research and engineering application.

  8. Impact of lubrication on the tribological behaviour of PTFE composites for guide rings application

    Indian Academy of Sciences (India)

    M TRABELSI; M KHARRAT; M DAMMAK

    2016-09-01

    In this study, the friction and wear behaviours of polytetrafluoroethylene (PTFE)-based composites were comparatively evaluated under dry sliding and oil-lubricated conditions. Two PTFE composites filled with bronze and bronze $+$ molybdenum disulfide (MoS$_2$) were considered. These composites were used as guide rings for hydraulic actuating cylinder. Friction and wear tests of the composite specimens sliding against high chromium steel ball were conducted using reciprocating linear tribometer. The wear mechanisms of the composites under the two different sliding conditions were analysed and discussed based on scanning electron microscopic (SEM) examinationsof the worn surface and optical micrographs of the steel counterface. Under the oil-lubricated condition, the friction and wear behaviours of the composites were considerably improved if compared to that under the dry sliding. The oil adsorbed layer limited the transfer of the composite to the steel counterface and avoided the oxidation of the MoS$_2$ during the sliding test.

  9. Ring Around a Galaxy

    Science.gov (United States)

    1999-01-01

    Space Telescope Science Institute astronomers are giving the public chances to decide where to aim NASA's Hubble Space Telescope. Guided by 8,000 Internet voters, Hubble has already been used to take a close-up, multi-color picture of the most popular object from a list of candidates, the extraordinary 'polar-ring' galaxy NGC 4650A. Located about 130 million light-years away, NGC 4650A is one of only 100 known polar-ring galaxies. Their unusual disk-ring structure is not yet understood fully. One possibility is that polar rings are the remnants of colossal collisions between two galaxies sometime in the distant past, probably at least 1 billion years ago. What is left of one galaxy has become the rotating inner disk of old red stars in the center. Meanwhile, another smaller galaxy which ventured too close was probably severely damaged or destroyed. The bright bluish clumps, which are especially prominent in the outer parts of the ring, are regions containing luminous young stars, examples of stellar rebirth from the remnants of an ancient galactic disaster. The polar ring appears to be highly distorted. No regular spiral pattern stands out in the main part of the ring, and the presence of young stars below the main ring on one side and above on the other shows that the ring is warped and does not lie in one plane. Determining the typical ages of the stars in the polar ring is an initial goal of our Polar Ring Science Team that can provide a clue to the evolution of this unusual galaxy. The HST exposures were acquired by the Hubble Heritage Team, consisting of Keith Noll, Howard Bond, Carol Christian, Jayanne English, Lisa Frattare, Forrest Hamilton, Anne Kinney and Zolt Levay, and guest collaborators Jay Gallagher (University of Wisconsin-Madison), Lynn Matthews (National Radio Astronomy Observatory-Charlottesville), and Linda Sparke (University of Wisconsin-Madison).

  10. Microstructure-Wear Resistance Correlation and Wear Mechanisms of Spark Plasma Sintered Cu-Pb Nanocomposites

    Science.gov (United States)

    Sharma, Amit Siddharth; Biswas, Krishanu; Basu, Bikramjit

    2014-01-01

    The dispersion of a softer phase in a metallic matrix reduces the coefficient of friction (COF), often at the expense of an increased wear rate at the tribological contact. To address this issue, unlubricated fretting wear tests were performed on spark plasma sintered Cu-Pb nanocomposites against bearing steel. The sintering temperature and the Pb content as well as the fretting parameters were judiciously selected and varied to investigate the role of microstructure (grain size, second-phase content) on the wear resistance properties of Cu-Pb nanocomposites. A combination of the lowest wear rate (~1.5 × 10-6 mm3/Nm) and a modest COF (~0.4) was achieved for Cu-15 wt pct Pb nanocomposites. The lower wear rate of Cu-Pb nanocomposites with respect to unreinforced Cu is attributed to high hardness (~2 to 3.5 GPa) of the matrix, Cu2O/Fe2O3-rich oxide layer formation at tribological interface, and exuding of softer Pb particles. The wear properties are discussed in reference to the characteristics of transfer layer on worn surface as well as subsurface damage probed using focused ion beam microscopy. Interestingly, the flash temperature has been found to have insignificant effect on the observed oxidative wear, and alternative mechanisms are proposed. Importantly, the wear resistance properties of the nanocomposites reveal a weak Hall-Petch-like relationship with grain size of nanocrystalline Cu.

  11. Mechanical seal having a single-piece, perforated mating ring

    Science.gov (United States)

    Khonsari, Michael M.; Somanchi, Anoop K.

    2007-08-07

    A mechanical seal (e.g., single mechanical seals, double mechanical seals, tandem mechanical seals, bellows, pusher mechanical seals, and all types of rotating and reciprocating machines) with reduced contact surface temperature, reduced contact surface wear, or increased life span. The mechanical seal comprises a rotating ring and a single-piece, perforated mating ring, which improves heat transfer by controllably channeling coolant flow through the single-piece mating ring such that the coolant is in substantially uniform thermal contact with a substantial portion of the interior surface area of the seal face, while maintaining the structural integrity of the mechanical seal and minimizing the potential for coolant flow interruptions to the seal face caused by debris or contaminants (e.g., small solids and trash) in the coolant.

  12. Structural transformations in wear resistance of iron- and cobalt-based amorphous alloys during abrasive wear

    Science.gov (United States)

    Korshunov, L. G.; Shabashov, V. A.; Chernenko, N. L.

    2010-04-01

    The wear resistance and structural changes in a number of amorphous alloys based on iron and cobalt and in high-carbon tool steels are studied during wear by a fixed abrasive (crondum, Carborundum) at room temperature and -196°C. The abrasive wear resistance of the amorphous alloys is shown to be 1.6-3.1 lower than that of the high-carbon tool steels having a similar hardness. The relatively low level of the abrasive wear resistance of the amorphous alloys is assumed to be caused by strain softening of their surface during wear. A nanocrystalline structure is found to form in local microvolumes in a thin deformed surface layer of the alloys.

  13. Wear properties of H13 with micron scale and nano scale grains bionic units processed by laser remelting

    Science.gov (United States)

    Zhang, Peng; Zhou, Hong; Wang, Cheng-tao; Liu, Yan; Ren, Lu-quan

    2013-12-01

    By simulating the cuticles of some soil animals, a combination of soft part (untreated substrate) and hard part (laser remelting area) structure was designed on metal surface to get an improved performance. Different specimens were prepared which contained units with micro and nano scale grains. The microstructures were observed by environmental field emission scanning electron microscopy. X-ray diffraction was used to identify the phases. The results of these tests indicate that due to the rapid solidification condition in the water, nano scale grains have a high microhardness between 1300 and 1000 HV. Retained austenite was found in it. Some of them transform to martensite in block on ring wear test. Specimens with bionic unit have a better wear resistance. Especially, the units with nano grains bring a further enhancement. The alternate soft and hard in macroscopic (substrate and laser remelting area) and microscopic (austenite and martensite) structure played a key role in improving the H13 wear resistance.

  14. Analysis on structural characteristics of rotors in twin-rotor cylinder-embedded piston engine

    Institute of Scientific and Technical Information of China (English)

    陈虎; 潘存云; 徐海军; 邓豪; 韩晨

    2014-01-01

    Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine can be applied. The quantity and forms of its sealing surfaces are reduced and simplified, and what’s more, the advantages of twin-rotor piston engine are inherited, such as high power density and no valve mechanism. Given the motion law of two rotors, its kinematic model is established, and the general expression for some parameters related to engine performance, such as the trajectory, displacement, velocity and acceleration of the piston and centroid trajectory, angular displacement, velocity and acceleration of the rod are presented. By selecting different variation patterns of relative angle of two rotors, the relevant variables are compared. It can be concluded that by designing the relative angle function of two rotors, the volume variation of working chamber can be changed. However, a comprehensive consideration for friction and vibration is necessary because velocity and acceleration are quite different in the different functions, the swing magnitude of rod is proportional to link ratioλ, and the position of rod swing center is controlled by eccentricitye. In order to reduce the lateral force, a smaller value ofλshould be selected in the case of the structure, and the value ofe should be near 0.95. There is no relationship between the piston stroke and the variation process of relative angle of two rotors, the former is only proportional to the amplitude of relative angle of two rotors.

  15. Neptune's ring system.

    Science.gov (United States)

    Porco, C. C.; Nicholson, P. D.; Cuzzi, J. N.; Lissauer, J. J.; Esposito, L. W.

    The authors review the current state of knowledge regarding the structure, particle properties, kinematics, dynamics, origin, and evolution of the Neptune rings derived from Earth-based and Voyager data. Neptune has a diverse system of five continuous rings - 2 broad (Galle and Lassell) and 3 narrow (Adams, Le Verrier, and Arago) - plus a narrow discontinuous ring sharing the orbit of one of its ring-region satellites, Galatea. The outermost Adams ring contains the only arcs observed so far in Voyager images. The five arcs vary in angular extent from ≡1° to ≡10°, and exhibit internal azimuthal structure with typical spatial scales of ≡0.5°. All five lie within ≡40° of longitude. Dust is present throughout the Neptune system and measureable quantities of it were detected over Neptune's north pole. The Adams ring (including the arcs) and the Le Verrier ring contain a significant fraction of dust. The Neptune ring particles are probably red, and may consist of ice "dirtied" with silicates and/or some carbon-bearing material. A kinematic model for the arcs derived from Voyager data, the arcs' physical characteristics, and their orbital geometry and phasing are all roughly in accord with single-satellite arc shepherding by Galatea, though the presence of small kilometer-sized bodies embedded either within the arcs or placed at their Lagrange points may explain some inconsistencies with this model.

  16. Algorithms for finite rings

    NARCIS (Netherlands)

    Ciocanea Teodorescu I.,

    2016-01-01

    In this thesis we are interested in describing algorithms that answer questions arising in ring and module theory. Our focus is on deterministic polynomial-time algorithms and rings and modules that are finite. The first main result of this thesis is a solution to the module isomorphism problem in

  17. Revocable Ring Signature

    Institute of Scientific and Technical Information of China (English)

    Dennis Y. W. Liu; Joseph K. Liu; Yi Mu; Willy Susilo; Duncan S. Wong

    2007-01-01

    Group signature allows the anonymity of a real signer in a group to be revoked by a trusted party called group manager. It also gives the group manager the absolute power of controlling the formation of the group. Ring signature, on the other hand, does not allow anyone to revoke the signer anonymity, while allowing the real signer to forma group (also known as a ring) arbitrarily without being controlled by any other party. In this paper, we propose a new variant for ring signature, called Revocable Ring Signature. The signature allows a real signer to form a ring arbitrarily while allowing a set of authorities to revoke the anonymity of the real signer. This new variant inherits the desirable properties from both group signature and ring signature in such a way that the real signer will be responsible for what it has signed as the anonymity is revocable by authorities while the real signer still has the freedom on ring formation. We provide a formal security model for revocable ring signature and propose an efficient construction which is proven secure under our security model.

  18. Illustration of Saturn's Rings

    Science.gov (United States)

    2001-01-01

    This illustration shows a close-up of Saturn's rings. These rings are thought to have formed from material that was unable to form into a Moon because of tidal forces from Saturn, or from a Moon that was broken up by Saturn's tidal forces.

  19. The Fermilab recycler ring

    Energy Technology Data Exchange (ETDEWEB)

    Martin Hu

    2001-07-24

    The Fermilab Recycler is a permanent magnet storage ring for the accumulation of antiprotons from the Antiproton Source, and the recovery and cooling of the antiprotons remaining at the end of a Tevatron store. It is an integral part of the Fermilab III luminosity upgrade. The following paper describes the design features, operational and commissioning status of the Recycler Ring.

  20. EBT ring physics

    Energy Technology Data Exchange (ETDEWEB)

    Uckan, N.A. (ed.)

    1980-04-01

    This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers. (MOW)