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

Selecting Material Properties for Maximizing Gun Firing Power

2014 ◽  
Author(s):  
J. Perry ◽  
M. Perl
Keyword(s):  
Detailed Analysis ◽  
Yield Stress ◽  
Bauschinger Effect ◽  
Strain Curve ◽  
Residual Stress Field ◽  
Transition Range ◽  
Effect Factor ◽  
Gun Barrel ◽  
Zero Offset ◽  
Gun Firing

The design of gun barrels aims at maximizing its firing power determined by its SMP — the maximal allowed firing pressure, which is considerably enhanced by inducing a favorable residual stress field through the barrel’s wall commonly by the autofrettage process. Presently, there are two distinct processes: hydrostatic and swage autofrettage. In both processes the barrel’s material is fully or partially plastically deformed. Recently, a 3-D code was developed, which finally enables a realistic simulation of both swage and hydraulic autofrettage, using the experimentally measured stress-strain curve, and incorporating the Bauschinger effect. This code enables a detailed analysis of all the factors involving the final SMP of a barrel, and it can be used to establish the optimal process for any gun barrel design. A major outcome of this analysis was the fact that the SMP of an autofrettaged barrel is dictated by the detailed plastic characteristics on the barrel’s material. The main five plastic parameters of the material that have been identified are: the exact (zero offset) value of the yield stress, the universal plastic curve in tension and in compression, the Bauschinger Effect Factor (BEF) curve, and the Elastic-Plastic Transition Range (EPTR). A detailed analysis of these three materials points to the fact that the major parameter determining the barrel’s SMP is the yield stress of the material and that the best way to determine it is by the newly developed “zero offset” method. All these four parameters have a greater influence on the SMP of an hydraulically autofrettaged barrel than on a swaged one.

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.

Experimental Data, Numerical Fit and Fatigue Life Calculations Relating to the Bauschinger Effect in High Strength Armament Steels

2003 ◽  
Vol 125 (3) ◽  
pp. 330-334 ◽  
Author(s):  
Edward Troiano ◽  
Anthony P. Parker ◽  
John Underwood ◽  
Charles Mossey
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Bauschinger Effect ◽  
High Strength Steels ◽  
High Strength ◽  
Strength Reduction ◽  
Plastic Strains ◽  
Test Results ◽  
Effect Factor ◽  
Modulus Reduction

The uniaxial Bauschinger effect has been evaluated in several high strength steels being considered for armament application. The steels investigated include ASTM A723 (1130 and 1330 MPa), PH 13-8 Mo stainless steel (1380 MPa), PH 13-8 Mo super tough stainless steel (1355 MPa), and HY 180 (1180MPa). Tests were conducted at plastic strains up to 3.5%. Results of testing show a progressive decrease in Bauschinger effect up to plastic strains of approximately 1% (for all materials investigated), after which there is little further decrease in the Bauschinger effect. Several key features were discovered during testing. First, all of the materials tested exhibited a changing modulus, where the elastic modulus on unloading after tensile plastic straining is consistently lower than that observed in the original loading of the specimens. The amount of modulus reduction is dependent upon the material tested, and larger reductions are observed with increasing amounts of tensile plastic strain. Prior work by Milligan reported Bauschinger effect factor β for a modified 4340 steel (old vintage A723 steel), which compares well with the present work. However, his results failed to mention any observations about a modulus reduction. The second observation was the expected strength reduction where a reduced compressive strength is observed as a result of prior tensile plastic straining. Numerical curve fits used to calculate residual stresses, which take into account both the modulus reduction and strength reduction are presented for all materials. Fatigue life calculations, utilizing the numerical curve fits, show good agreement with full size A723 laboratory fatigue test results.

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.

The Evaluation of the 3-D Residual Stress Field Due to Hydraulic Autofrettage in a Finite Length Cylinder Incorporating the Bauschinger Effect Factor Based on the “Zero Offset Yield Stress”

2008 ◽  
Author(s):  
J. Perry ◽  
M. Perl
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Yield Stress ◽  
Yield Point ◽  
Finite Length ◽  
Bauschinger Effect ◽  
Residual Stress Field ◽  
Tangential Strain ◽  
Effect Factor ◽  
Zero Offset

The autofrettage process increases the ability of a pressurized cylinder to withstand higher pressure values prior to the onset of yielding. The yield-pressure of an autofrettaged cylinder is strongly affected by the Bauschinger Effect (BE) that results in a reduction of the yield stress in compression. This reduction, which is measured by the Bauschinger Effect Factor (BEF), highly depends on the exact determination of the yield point. The present analysis suggests a new 3-D axisymmetric model for solving the residual stress field in a hydraulically autofrettaged finite-length cylinder including the BEF curve evaluated by using the newly proposed concept of the “zero offset” yield point definition. The numerical model is validated experimentally using axial and tangential strain gauges attached to a thick walled cylinder undergoing hydraulic pressurization. The experimental set-up enables continuous strain measurements vs. the increasing pressure. The calculated strains and displacements as well as the initial yield-pressure were found to be in very good agreement with the measured values.

Bauschinger Effect Investigation of an Aluminum Alloy, and Its Application in Autofrettaged and Compound Tubes

2007 ◽  
Author(s):  
M. Mohammadi ◽  
G. H. Farrahi ◽  
S. H. Hoseini
Keyword(s):  
Aluminum Alloy ◽  
Residual Stresses ◽  
Bauschinger Effect ◽  
Testing Machine ◽  
Isotropic Hardening ◽  
Compression Tests ◽  
Effect Factor ◽  
Hardening Rule ◽  
Instron Testing Machine ◽  
Shrink Fit

For characterizing Bauschinger effect factor (BEF) and Bauschinger modulus reduction of an A5083 aluminum alloy experimentally, several uniaxial tension-compression tests carried out in different pre-strain levels using INSTRON testing machine. BEF was investigated using both Welter and Milligan’s definitions for various offset values. It was observed that Milligan’s definition predicts BEF less than Welter’s definition for all offset values. In addition, real loading-unloading behavior of such alloy was recorded to predict residual stresses resulting from autofrettage and shrink fit processes. Variable material properties (VMP) method, which is capable of incorporating real unloading behavior of materials, was used as an accurate way to estimate residual stresses. Hoop residual stresses were calculated using real unloading behavior and isotropic hardening rule. Results showed that, isotropic hardening rule in comparison with real unloading behavior overestimates bore hoop residual stresses up to 12%.

Water quality assessment and apportionment source of pollution from neighbouring rivers in the Tapeng Lagoon (Taiwan) using multivariate analysis: a case study

2006 ◽  
Vol 54 (11-12) ◽  
pp. 47-55 ◽  
Author(s):  
S.-W. Liao ◽  
J.-Y. Sheu ◽  
J.-J. Chen ◽  
C.-G. Lee
Keyword(s):  
Water Quality ◽  
Water Resource Management ◽  
Pollution Prevention ◽  
Water Quality Assessment ◽  
Stream Pollution ◽  
Effect Factor ◽  
Habitat Recovery ◽  
Quality Of Water ◽  
Source Of Pollution

Factor analysis was conducted to explain the characteristics and variation in the quality of water during the disassembly of oyster frames and fishery boxes. The result shows that the most important latent factors in the Tapeng Lagoon are the ocean factor, the primary productivity factor, and the fishery pollution factor. Canonical discriminant analysis is applied to identify the source of pollution in neighbouring rivers outside the Tapeng Lagoon. The two constructed discriminant functions (CDFs) showed a marked contribution to all the discriminant variables, and that total nitrogen, algae, dissolved oxygen, and total phosphate combined in the nutrient effect factor. The recognition capacities in these two CDFs were 95.6% and 4.4%, respectively. The water quality in the Kaoping river most strongly affected the water quality in the Tapeng Lagoon. Disassembling the oyster frames and fishery boxes improved the water quality markedly. However, environmental topographic conditions indicate that strengthening stream pollution prevention and constructing another entrance to the ocean are the best approaches for improving the quality of water in the Tapeng Lagoon by reducing eutrophication. These approaches and results yield useful information concerning habitat recovery and water resource management.

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