Effect of machining residual stresses on the repetitive impact behavior of silicon nitride

1995 ◽  
Vol 10 (1) ◽  
pp. 95-100 ◽  
Author(s):  
Sreeram Srinivasan ◽  
Peter J. Blau ◽  
Julia L. Bjerke
Keyword(s):  
Silicon Nitride ◽  
Residual Stresses ◽  
Internal Combustion Engines ◽  
Wear Behavior ◽  
Ceramic Materials ◽  
Impact Behavior ◽  
Combustion Engines ◽  
Silicon Nitride Ceramic ◽  
Repetitive Impact ◽  
The Impact

Silicon nitride is a candidate valve material for internal combustion engines. Its low density and attractive mechanical properties relative to conventional metallic alloys portend significant improvements in valve performance. The production of valves involves a significant amount of machining, especially grinding. Grinding of ceramic materials may result in surface and subsurface damage in the form of fracture or residual stresses which may affect impact behavior and, consequently, the behavior of silicon nitride ceramic materials as valves. The effects of residual stresses due to grinding on the impact wear behavior of one silicon nitride composition ground under various conditions have been investigated.

scholarly journals Experiment on Foreign Object Damage of Gas Turbine-Grade Silicon Nitride Ceramic

1998 ◽  
Author(s):  
Hiro Yoshida ◽  
Takashi Nakashima ◽  
Makoto Yoshida ◽  
Yasushi Hara ◽  
Toru Shimamori
Keyword(s):  
Elevated Temperature ◽  
Silicon Nitride ◽  
Elevated Temperatures ◽  
Tensile Load ◽  
Strength Degradation ◽  
Spall Fracture ◽  
Silicon Nitride Ceramic ◽  
Impact Tests ◽  
The Impact ◽  
Bending Fracture

A new high quality turbine system using monolithic silicon-nitride ceramic is under development. In this study particle impact tests of the silicon-nitride have been tried at room and elevated temperatures with and without tensile load, which simulates centrifugal force of blade rotation. In the experiment 1 mm diameter particle is impacted at velocities up to 900 m s−1. In this paper, critical velocities for bending fracture and Hertzian cracks are examined. Moreover, strength degradation at elevated temperature and spall fracture of the blade are discussed. The main results are: 1) The bending fracture mode critical impact velocity for soft particles is higher than that for hard particles. 2)The impact parameter ϕ for initiation of Hertzian cracks ranges 1.08×10−5 – 1.56×10−5 for the materials tested. 3)Strength degradation at elevated temperature was clearly observed. 4) In the impact tests on blades spall fracture, which was caused by interaction of stress waves, appeared.

scholarly journals Impact of Blow-By Gas and Endgap Ring Position on the Variations of Particle Emissions in Gasoline Engines

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7492
Author(s):  
Vincent Berthome ◽  
David Chalet ◽  
Jean-François Hetet
Keyword(s):  
Internal Combustion Engines ◽  
Particulate Emissions ◽  
Combustion Engines ◽  
Spark Ignition Engines ◽  
Particulate Emission ◽  
Particle Emissions ◽  
Gasoline Engines ◽  
System A ◽  
The Impact ◽  
Ring Position

Particulate emission from internal combustion engines is a complex phenomenon that needs to be understood in order to identify its main factors. To this end, it appears necessary to study the impact of unburned gases, called blow-by gases, which are reinjected into the engine intake system. A series of transient tests demonstrate their significant contribution since the particle emissions of spark-ignition engines are 1.5 times higher than those of an engine without blow-by with a standard deviation 1.5 times greater. After analysis, it is found that the decanter is not effective enough to remove completely the oil from the gases. Tests without blow-by gases also have the advantage of having a lower disparity, and therefore of being more repeatable. It appears that the position of the “endgap” formed by the first two rings has a significant impact on the amount of oil transported towards the combustion chamber by the backflow, and consequently on the variation of particle emissions. For this engine and for this transient, 57% of the particulate emissions are related to the equivalence ratio, while 31% are directly related to the ability of the decanter to remove the oil of the blowby gases and 12% of the emissions come from the backflow. The novelty of this work is to relate the particles fluctuation to the position of the endgap ring.

scholarly journals Smart ceramic materials for homogeneous combustion in internal combustion engines: A review

2009 ◽  
Vol 13 (3) ◽  
pp. 153-163 ◽  
Author(s):  
Kannan Chidambaram ◽  
Tamilporai Packirisamy
Keyword(s):  
Combustion Chamber ◽  
Internal Combustion Engines ◽  
Porous Ceramic ◽  
Ceramic Materials ◽  
Combustion Engines ◽  
Emission Level ◽  
Engine Cylinder ◽  
Homogeneous Combustion ◽  
Zero Emission ◽  
Porous Ceramic Materials

The advantages of using ceramics in advanced heat engines include increased fuel efficiency due to higher engine operating temperatures, more compact designs with lower capacity cooling system. Future internal combustion engines will be characterized by near zero emission level along with low specific fuel consumption. Homogenous combustion which realized inside the engine cylinder has the potential of providing near zero emission level with better fuel economy. However, the accomplishment of homogeneous combustion depends on the air flow structure inside the combustion chamber, fuel injection conditions and turbulence as well as ignition conditions. Various methods and procedures are being adopted to establish the homogeneous combustion inside the engine cylinder. In recent days, porous ceramic materials are being introduced inside the combustion chamber to achieve the homogeneous combustion. This paper investigates the desirable structures, types, and properties of such porous ceramic materials and their positive influence on the combustion process.

Application of Nonlinear Vibration Absorbers to the Control of Piston Secondary Motion in Internal Combustion Engines

2015 ◽  
Author(s):  
Nader Dolatabadi ◽  
Stephanos Theodossiades ◽  
Steve J. Rothberg
Keyword(s):  
Internal Combustion Engines ◽  
Passive Control ◽  
Internal Combustion ◽  
Impact Behavior ◽  
Combustion Engines ◽  
Impulsive Behavior ◽  
Control Approach ◽  
Operation Conditions ◽  
Secondary Motion ◽  
Nonlinear Energy

The impulsive behavior of piston plays a key role in the Noise, Vibration and Harshness (NVH) of internal combustion engines. There have been several studies on the identification and quantification of piston impacting action under various operation conditions. In the current study, the dynamics of piston secondary motion are briefly explored, since this is fundamental to understanding the aggressive oscillations, energy loss and noise generation. Concepts of controlling piston secondary motion (and thus, impacts) are investigated and a new passive control approach is presented based on the nonlinear energy absorption of the highly transient oscillations. The effectiveness of this new method on the improvement of piston impact behavior is discussed, using a preliminary optimization exercise (with respect to engine excitation/speed, damping and stiffness of the nonlinear oscillator) that leads to the conceptual design of a nonlinear energy absorber.

Clearance Effects on the Impact Behavior of Large Aspect Ratio Silicon Journal Microbearings

2010 ◽  
Author(s):  
S. Demiri ◽  
S. Boedo
Keyword(s):  
Wear Behavior ◽  
Coefficient Of Restitution ◽  
Journal Bearings ◽  
Impact Behavior ◽  
Radial Clearance ◽  
Test Apparatus ◽  
Rotor Speed ◽  
Dynamic Impact ◽  
The Impact ◽  
Bearing System

This paper investigates the effect of bearing clearance on the impact behavior of microfabricated silicon journal bearings. The design of a novel test apparatus to assess microbearing wear behavior is presented. Microbearing designs, microfabrication processes, and metrology characterization techniques are discussed. A dynamic impact model of the bearing system based on classical impulse-momentum relations is formulated in order to assess the effect of clearance on rotor speed. Coefficient of restitution values obtained over the range of kinematically allowable radial clearance specifications are found to agree well with previously published results for polysilicon microstructures.

scholarly journals Enhancing the Geometrical Performance Using Initially Conical Cylinder Liner in Internal Combustion Engines—A Numerical Study

2020 ◽  
Vol 10 (11) ◽  
pp. 3705
Author(s):  
Ahmad Alshwawra ◽  
Florian Pohlmann-Tasche ◽  
Frederik Stelljes ◽  
Friedrich Dinkelacker
Keyword(s):  
Internal Combustion Engines ◽  
Thermal Stresses ◽  
Numerical Study ◽  
Cylinder Liner ◽  
Internal Combustion ◽  
Friction Reduction ◽  
Cylindrical Shape ◽  
Combustion Engines ◽  
Cold State ◽  
The Impact

Reducing friction is an important aspect to increase the efficiency of internal combustion engines (ICE). The majority of frictional losses in engines are related to both the piston skirt and piston ring–cylinder liner (PRCL) arrangement. We studied the enhancement of the conformation of the PRCL arrangement based on the assumption that a suitable conical liner in its cold state may deform into a liner with nearly straight parallel walls in the fired state due to the impact of mechanical and thermal stresses. Combining the initially conical shape with a noncircular cross section will bring the liner even closer to the perfect cylindrical shape in the fired state. Hence, a significant friction reduction can be expected. For the investigation, the numerical method was first developed to simulate the liner deformation with advanced finite element methods. This was validated with given experimental data of the deformation for a gasoline engine in its fired state. In the next step, initially conically and/or elliptically shaped liners were investigated for their deformation between the cold and fired state. It was found that, for liners being both conical and elliptical in their cold state, a significant increase of straightness, parallelism, and roundness was reached in the fired state. The combined elliptical-conical liner led to a reduced straightness error by more than 50% compared to the cylindrical liner. The parallelism error was reduced by 60% to 70% and the roundness error was reduced between 70% and 80% at different liner positions. These numerical results show interesting potential for the friction reduction in the piston-liner arrangement within internal combustion engines.

scholarly journals Experimental study on noise reduction and performance enhancement for internal combustion engines

2020 ◽  
Vol 318 ◽  
pp. 01014
Author(s):  
Ioan Radu Şugar ◽  
Mihai Banica
Keyword(s):  
Experimental Study ◽  
Combustion Chamber ◽  
Noise Reduction ◽  
Fuel Consumption ◽  
Internal Combustion Engines ◽  
Performance Enhancement ◽  
Ceramic Materials ◽  
Combustion Engines ◽  
Large Cities ◽  
And Performance

As the number of cars increases and large cities become more and more crowded, noise reduction becomes more and more important. The decrease of the fuel consumption and the increase of power to the same cylindrical capacity are always current topics. This paper’s aim is to bring a contribution to solving these problems. The proposed solution consists in the use of ceramic materials in the design of the combustion chamber.

scholarly journals The Impact of Powering an Engine with Fuels from Renewable Energy Sources including its Software Modification on a Drive Unit Performance Parameters

2019 ◽  
Vol 11 (23) ◽  
pp. 6585 ◽  
Author(s):  
Markiewicz ◽  
Muślewski
Keyword(s):  
Renewable Energy ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Renewable Energy Sources ◽  
Internal Combustion ◽  
Energy Sources ◽  
Exhaust Emission ◽  
Combustion Engines ◽  
Performance Parameters ◽  
The Impact

The application of fuels from renewable energy sources for combustion engine powering involves a great demand for this kind of energy while its production infrastructure remains underdeveloped. The use of this kind of fuel is supposed to reduce the emission of greenhouse gases and the depletion of natural resources and to increase the share of renewable energy sources in total energy consumption and thus support sustainable development in Europe. This study presents the results of research on selected performance parameters of transport by internal combustion engines including: power, torque, the emission of sound generated by the engine, the content of exhaust components (oxygen O2, carbon monoxide CO, carbon dioxide CO2, nitrogen dioxide NO2), and the content of particulate matter (PM) in exhaust emission. Three self-ignition engines were tested. The fuel injection controllers of the tested internal combustion engines were additionally adjusted by increasing the fuel dose and the load of air. The material used in the tests were mixtures of diesel oil and fatty acid methyl esters of different concentration. A statistical analysis was performed based of the results. The purpose of the work was to develop a resulting model for assessing the operation of engines fueled with biofuel and diesel mixtures while changing the vehicle's computer software. A computer simulation algorithm was also developed for the needs of the tests which was used to prognose the state of the test results for variable input parameters.

Sign in / Sign up

Export Citation Format

Share Document