Plastic Deformation Influence on Material Properties of Autofrettaged Tubes Used in Diesel Engines Injection System

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
K. Aliakbari ◽  
Kh. Farhangdoost
Keyword(s):  
Plastic Deformation ◽  
Yield Strength ◽  
Diesel Engines ◽  
Bauschinger Effect ◽  
Injection System ◽  
Suitable Model ◽  
Operating Pressure ◽  
Effect Factor ◽  
Loading And Unloading ◽  
High Pressure Injection

According to the DIN2391 standard, the DIN1.0406 steel is used to manufacture high-pressure injection tubes of diesel engines. The parts are autofrettaged during the manufacturing process to increase operating pressure and fatigue life. The autofrettage process is affected by loading–unloading cycle. In Bauschinger effect (BE) phenomenon, plastic deformation causes a loss in unloading yield strength. The ratio of unloading yield strength to the loading yield strength is called Bauschinger effect factor, BEF. In this paper, plastic deformation influence on the loading and unloading behaviors of DIN1.0406 steel is studied considering the BE. Uniaxial tension–compression experimental data are used to figure out a suitable model to study the BE. To carry out these experiments, a servohydraulic Instron machine is used. The sample tubes having inside diameter of 2.4 mm and outside diameter of 6 mm were made based on the standard ASTM E8M-97a. The tests were carried out using the total strain of 4.31%. Another important purpose of this paper is to investigate the effect of the amount of plastic strain on loading–unloading Young's modulus. Finally, the behavior of DIN1.0406 steel is compared with the steels such as DIN1.6959, HY 180, and PH 13-8Mo used in tubes.

Analysis of the spherical indentation cycle for elastic–perfectly plastic solids

2004 ◽  
Vol 19 (12) ◽  
pp. 3641-3653 ◽  
Author(s):  
L. Kogut ◽  
K. Komvopoulos
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Elastic Modulus ◽  
Yield Strength ◽  
Material Properties ◽  
Deformation Behavior ◽  
Plastic Material ◽  
Elastic Plastic ◽  
Loading And Unloading ◽  
Elastic Plastic Material

A finite element analysis of frictionless indentation of an elastic–plastic half-space by a rigid sphere is presented and the deformation behavior during loading and unloading is examined in terms of the interference and elastic–plastic material properties. The analysis yields dimensionless constitutive relationships for the normal load, contact area, and mean contact pressure during loading for a wide range of material properties and interference ranging from the inception of yielding to the initiation of fully plastic deformation. The boundaries between elastic, elastic–plastic, and fully plastic deformation regimes are determined in terms of the interference, mean contact pressure, and reduced elastic modulus-to-yield strength ratio. Relationships for the hardness and associated interference versus elastic–plastic material properties and truncated contact radius are introduced, and the shape of the plastic zone and maximum equivalent plastic strain are interpreted in light of finite element results. The unloading response is examined to evaluate the validity of basic assumptions in traditional indentation approaches used to measure the hardness and reduced elastic modulus of materials. It is shown that knowledge of the deformation behavior under both loading and unloading conditions is essential for accurate determination of the true hardness and reduced elastic modulus. An iterative approach for determining the reduced elastic modulus, yield strength, and hardness from indentation experiments and finite element solutions is proposed as an alternative to the traditional method.

Single sample method for assessing the Baushinger effect

2020 ◽  
Vol 86 (7) ◽  
pp. 55-58
Author(s):  
A. D. Khvan ◽  
D. V. Khvan ◽  
A. A. Voropaev
Keyword(s):  
Plastic Deformation ◽  
Stress State ◽  
Yield Strength ◽  
Bauschinger Effect ◽  
Calculated Data ◽  
Compressive Yield Strength ◽  
Special Device ◽  
Compression Tests ◽  
Traditional Procedure

The Bauschinger effect is one of the fundamental properties of most metal alloys exposed to plastic deformation under non-monotonic loading. Development of the methods for quantifying this effect is one the important issues of the theory of plasticity. Calculation of the parameter characterizing the aforementioned effect is required for determination of the stress state in plastically deformable blanks upon pressure metal treatment. The value of the parameter (determined in standard tensile tests followed by subsequent compression of samples) is defined by the ratio of the conditional yield strength of the sample under compression to the value of the preliminary tensile stress. A series of cylindrical samples (~10 pcs.) is usually taken for tensile-compression tests. According to the traditional procedure, long-size standard specimens are pre-stretched to various degrees of plastic deformation. After that short specimens are cut out from those specimens for compression tests to determine the conditional compressive yield strength with a tolerance of 0.2% for plastic deformation. Such a procedure is rather time consuming and expensive. We propose and develop a new single-model method for estimating the Bauschinger effect which consists in testing of a single long-size specimen for tension followed by compression of the specimen in a special device providing deformation of a previously stretched specimen without flexure under conditions of a linear stress state. The device was designed, manufactured and underwent the appropriate tests. The device contains supporting elements in the form of conical-shaped sectors that prevent flexure of a long cylindrical specimen upon compression, a ratio of the working part length to diameter ranges from 5 to 10. The results of experimental determination of the parameter β characterizing the indicated effect are presented. The results of comparing the values of the parameter β determined by the developed and traditional methods revealed the possibility of determining the parameter β using the proposed method. To reduce the complexity of performing tests related to determination of the parameter β we approximated it in the form of an exponent as a function of the magnitude of plastic deformation and determine the only one value of β0 under plastic deformations exceeding 0.05. In this regard, β0 can be considered a new characteristic of the material. The calculated data are in good agreement with the experimental results. The values of β0 are determined for a number of studied steel grades.

Prediction of Residual Stresses in an Autofrettaged Thick–Walled Cylinder

1983 ◽  
Vol 22 ◽  
Author(s):  
Peter C. T. Chen
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Bauschinger Effect ◽  
Residual Stress Distribution ◽  
Effect Factor ◽  
Hardening Effect ◽  
Loading And Unloading ◽  
Reverse Yielding ◽  
Walled Cylinder ◽  
Elastic Unloading

ABSTRACTMost of the earlier results for residual stresses are based on the assumption of elastic unloading. In this paper, the prediction of residual stresses for the case of reverse yielding including the combined Bauschinger and hardening effect will be reported for an autofrettaged thick-walled cylinder. The Bauschinger effect factor is varying as a function of overstrain. The strain-hardening effect is considered with different parameters used for loading and unloading process. The new results indicate that the influence of the combined Bauschinger and hardening effect on residual stress distribution is significant.

The Choice of Vibroacoustic Signal Measures in Mechanical Fault Diagnosis of Diesel Engines

2015 ◽  
Vol 236 ◽  
pp. 220-227 ◽  
Author(s):  
Zbigniew Dąbrowski ◽  
Maciej Zawisza
Keyword(s):  
Power Unit ◽  
Diesel Engines ◽  
Early Stage ◽  
Diagnostic System ◽  
Fuel Mixture ◽  
Injection System ◽  
Vibroacoustic Signal ◽  
Basic Power ◽  
Basic Features ◽  
High Pressure Injection

The use of diesel engines as a basic power unit of electric generators in big ship crafts and as a power unit in smaller ship crafts is very common. Low fuel consumption, high resistance to overload and long life span are the basic features which made these engines so commonly used. The development of electronic control of high pressure injection systems of the engine made the service of such an engine not so simple any more. What is more, control systems are directed at reducing fumes toxicity, which does not have to go hand in hand with early detection of engine damages. It happens in the case of a particular group of mechanical damages of the engine, which are undetectable by an onboard diagnostic system in the early stage of the development. The injection system is able to choose regulation parameters in such a way so that the composition of the air fuel mixture is in optimal range, and as a result it hides the information about the damage.This paper presents the results of analysis of the usefulness of the chosen vibroacoustic signal measures in the process of detecting damages of this type.

scholarly journals Possibilities of Simultaneous In-Cylinder Reduction of Soot andNOxEmissions for Diesel Engines with Direct Injection

2008 ◽  
Vol 2008 ◽  
pp. 1-13 ◽  
Author(s):  
U. Wagner ◽  
P. Eckert ◽  
U. Spicher
Keyword(s):  
Nitrogen Oxide ◽  
Diesel Engines ◽  
Fuel Injection ◽  
Soot Formation ◽  
Soot Oxidation ◽  
The Other ◽  
Injection System ◽  
Nitrogen Oxide Emissions ◽  
Injection Strategy ◽  
Soot Emissions

Up to now, diesel engines with direct fuel injection are the propulsion systems with the highest efficiency for mobile applications. Future targets in reducingCO2-emissions with regard to global warming effects can be met with the help of these engines. A major disadvantage of diesel engines is the high soot and nitrogen oxide emissions which cannot be reduced completely with only engine measures today. The present paper describes two different possibilities for the simultaneous in-cylinder reduction of soot and nitrogen oxide emissions. One possibility is the optimization of the injection process with a new injection strategy the other one is the use of water diesel emulsions with the conventional injection system. The new injection strategy for this experimental part of the study overcomes the problem of increased soot emissions with pilot injection by separating the injections spatially and therefore on the one hand reduces the soot formation during the early stages of the combustion and on the other hand increases the soot oxidation later during the combustion. Another method to reduce the emissions is the introduction of water into the combustion chamber. Emulsions of water and fuel offer the potential to simultaneously reduceNOxand soot emissions while maintaining a high-thermal efficiency. This article presents a theoretical investigation of the use of fuel-water emulsions in DI-Diesel engines. The numerical simulations are carried out with the 3D-CFD code KIVA3V. The use of different water diesel emulsions is investigated and assessed with the numerical model.

The overstrain of Thick-Walled cylinders considering the bauschinger effect factor (BEF)

2003 ◽  
Vol 17 (4) ◽  
pp. 477-483 ◽  
Author(s):  
A. Ghorbanpour ◽  
A. Loghman ◽  
H. Khademizadeh ◽  
M. Moradi
Keyword(s):  
Bauschinger Effect ◽  
Effect Factor

A New Method Developed for Brittle and Ductile Materials to Evaluate Mechanical Properties of a Lump Specimen in the Use of Indentation Test

2006 ◽  
Vol 129 (2) ◽  
pp. 284-292 ◽  
Author(s):  
Pal Jen Wei ◽  
Jen Fin Lin
Keyword(s):  
Yield Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Elastic Recovery ◽  
Indentation Test ◽  
New Method ◽  
Ductile Materials ◽  
Conventional Material ◽  
Loading And Unloading ◽  
Logarithm Function

In this study, the load-depth (P‐h) relationships matching the experimental results of the nanoindentation tests exhibited at the subregions of small and large depths are obtained, respectively. The relationships associated with these two subregions are then linked by the hyperbolic logarithm function to attain a single expression that is applied in the evaluation of the specimen’s elastic recovery ability, as shown in the unloading process. A new method is developed in the present study to evaluate both Young’s modulus and the yield strength of either a ductile or brittle material through the uses of the appropriate P‐h relationships developed in the load and unloading processes. The results of the Young’s modulus and the yield strength achieved by the present method are compared to those obtained from the conventional material tests for a lump material. The scattering of the experimental data shown in the loading and unloading processes are also interpreted by different causes.

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