An Axisymmetric Stress Release Method for Measuring the Autofrettage Level in Thick-Walled Cylinders—Part I: Basic Concept and Numerical Simulation

1994 ◽  
Vol 116 (4) ◽  
pp. 384-388 ◽  
Author(s):  
M. Perl ◽  
R. Arone´
Keyword(s):  
Empirical Relation ◽  
Pilot Test ◽  
Stress Release ◽  
Residual Stress Field ◽  
Hoop Strain ◽  
Experimental Procedure ◽  
Strain Measurements ◽  
Gun Barrel ◽  
Element Simulation ◽  
Release Method

A new experimental method for measuring the level of autofrettage in thick-walled cylinders is suggested. The method is based on measuring the hoop-strain while axisymmetrically releasing the residual stress field prevailing in the cylinder’s wall. A parametric study of the proposed experimental procedure conducted by a finite element simulation yields a simple empirical relation, which readily enables determining the actual autofrettage level from the strain measurements. This relation is found to be practically unique for all relevant cases, i.e., cylinders with radii ratios of b/a=1.6÷2.2 and autofrettage percents of φ=50–100 percent. A pilot test conducted on a 105-mm autofrettaged gun barrel, which experimentally validates the proposed procedure, is presented in Part II (Perl and Arone, 1994) of this paper.

An Axisymmetric Stress Release Method for Measuring the Autofrettage Level in Thick-Walled Cylinders—Part II: Experimental Validation

1994 ◽  
Vol 116 (4) ◽  
pp. 389-395 ◽  
Author(s):  
M. Perl ◽  
R. Arone´
Keyword(s):  
Numerical Simulation ◽  
Cost Effective ◽  
Preliminary Test ◽  
Residual Stress Field ◽  
Minimum Thickness ◽  
Experimental Procedure ◽  
Gun Barrel ◽  
Quantitative Monitoring ◽  
Release Method ◽  
Gradual Release

The basic concept of a new experimental method for measuring the level of autofrettage in thick-walled cylinders as well as a comprehensive numerical simulation were presented in Part I of this paper. A pilot test is conducted herein on a 105-mm autofrettage gun barrel to validate the proposed procedure. First, a preliminary test is performed to determine the minimum thickness required for a ring, cut from the barrel, in order to be a representative, valid, and free of edge-effect specimen. Then, the main experiment is conducted consisting of the gradual release of the residual stress field due to autofrettage prevailing in the ring specimen. An array of seven equally spaced, identical, radial notches is progressively cut at the inner surface of the ring, while the released hoop stress is continuously measured by a strain gage-based computerized data acquisition system. The process is accomplished by a detailed numerical simulation enabling a qualitative and quantitative monitoring of the procedure. The proposed experimental procedure is found to be feasible, reliable, and cost-effective, and to yield accurate results.

An Improved Split-Ring Method for Measuring the Level of Autofrettage in Thick-Walled Cylinders

1998 ◽  
Vol 120 (1) ◽  
pp. 69-73 ◽  
Author(s):  
M. Perl
Keyword(s):  
Residual Stress ◽  
Test Specimen ◽  
Opening Angle ◽  
Residual Stress Field ◽  
Hoop Strain ◽  
Approximate Relation ◽  
Split Ring ◽  
Strain Measurements ◽  
Ring Method

A simple, yet improved, experimental method for measuring the level of autofrettage in thick-walled cylinders, such as gun barrels, is proposed. A representative ring cut from the barrel serves as the test specimen. The ring is split by cutting it radially, while measuring the released hoop strain at the inner and outer surfaces diametrically opposite from the split line. The opening angle resulting from the spring apart from the ring is also monitored. An analysis based on Hill’s residual stress field yields an approximate relation which readily enables the determination of the prevailing level of autofrettage from strain measurements as well as from the value of the opening angle. This relation is found to be practically universal for all relevant cylinder configurations b/a = 1.6–2.2 and all levels of autofrettage of up to φ = 100 percent.

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.

Elasto-Plastic Stresses in Thick Walled Cylinders

2003 ◽  
Vol 125 (3) ◽  
pp. 248-252 ◽  
Author(s):  
Joseph Perry ◽  
Jacob Aboudi
Keyword(s):  
Residual Stress ◽  
Yield Criterion ◽  
Plastic Region ◽  
Weight Ratio ◽  
Theoretical Development ◽  
Cylinder Wall ◽  
Residual Stress Field ◽  
Gun Barrel ◽  
Von Mises ◽  
Made In

In the optimal design of a modern gun barrel, there are two main objectives to be achieved: increasing its strength-weight ratio and extending its fatigue life. This can be carried out by generating a residual stress field in the barrel wall, a process known as autofrettage. It is often necessary to machine the autofrettaged cylinder to its final configuration, an operation that will remove some of the desired residual stresses. In order to achieve a residual stress distribution which is as close as possible to the practical one, the following assumptions have been made in the present research on barrel analysis: A von Mises yield criterion, isotropic strain hardening in the plastic region in conjunction with the Prandtl-Reuss theory, pressure release taking into consideration the Bauschinger effect and plane stress conditions. The stresses are calculated incrementally by using the finite difference method, whereby the cylinder wall is divided into N-rings at a distance Δr apart. Machining is simulated by removing rings from both sides of the cylindrical surfaces bringing the cylinder to its final shape. After a theoretical development of the procedure and writing a suitable computer program, calculations were performed and a good correlation with the experimental results was found. The numerical results were also compared with other analytical and experimental solutions and a very good correlation in shape and magnitude has been obtained.

The Influence of the Bauschinger Effect on the Yield Stress, Young’s Modulus, and Poisson’s Ratio of a Gun Barrel Steel

2005 ◽  
Vol 128 (2) ◽  
pp. 179-184 ◽  
Author(s):  
J. Perry ◽  
M. Perl ◽  
R. Shneck ◽  
S. Haroush
Keyword(s):  
Plastic Deformation ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Bauschinger Effect ◽  
Young's Modulus ◽  
Poisson's Ratio ◽  
Compression Tests ◽  
Residual Stress Field ◽  
Gun Barrel

The Bauschinger effect (BE) was originally defined as the phenomenon whereby plastic deformation causes a loss of yield strength restraining in the opposite direction. The Bauschinger effect factor (BEF), defined as the ratio of the yield stress on reverse loading to the initial yield stress, is a measure of the magnitude of the BE. The aim of the present work is to quantitatively evaluate the influence of plastic deformation on other material properties such as Young’s modulus and Poisson’s ratio for gun barrel steel, thus extending the definition of the Bauschinger effect. In order to investigate the change in this material’s properties resulting from plastic deformation, several uniaxial tension and compression tests were performed. The yield stress and Young’s modulus were found to be strongly affected by plastic strain, while Poisson’s ratio was not affected at all. An additional result of these tests is an exact zero offset yield point definition enabling a simple evaluation of the BEF. A simple, triphase test sufficient to characterize the entire elastoplastic behavior is suggested. The obtained experimental information is readily useful for autofrettage residual stress field calculations.

A Method for Measurement of Axisymmetric Axial Residual Stresses in Circumferentially Welded Thin-Walled Cylinders

1985 ◽  
Vol 107 (3) ◽  
pp. 181-185 ◽  
Author(s):  
Weili Cheng ◽  
Iain Finnie
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Axial Component ◽  
Residual Stress Field ◽  
Strain Measurements ◽  
Thin Walled ◽  
Predicted Values ◽  
Inside Wall ◽  
Good Agreement

A new method is proposed for measuring the axial component of an axisymmetric residual stress field in thin-walled cylinders. The specific application considered is determination of the stress at the centerline of a circumferential weld. The method involves strain measurements at the outside wall while a complete circumferential slit is cut to increasing depths from the inside wall. The technique is applied to the simple case of a single pass weld. Experimental results are in good agreement with predicted values.

Experimental Verification of Model Pressurized Thick-Walled Cylinder With Numerical and Theoretical Methods

2011 ◽  
Author(s):  
Sunilbhai P. Macwan ◽  
Zhong Hu ◽  
Fereidoon Delfanian
Keyword(s):  
Hoop Stress ◽  
High Stress ◽  
Numerical Data ◽  
Cylinder Wall ◽  
Hoop Strain ◽  
Cylindrical Structures ◽  
Component Testing ◽  
Element Simulation ◽  
Pressurized Cylinder ◽  
Walled Cylinder

Pressurized thick-walled cylinders undergo repeated cycles of high stress and temperatures that may severely shorten the life of the component. Testing pressurized cylinder can help to evaluate the strength of the cylinder. This research seeks to determine the pressure to which the component is subjected by instrumenting the outside of the cylinder, and to evaluate hoop strain and hoop stress of the internal and external surface of the pressurized thick-walled cylinder. This study provides experimental results and then compares them with theoretical and numerical data for the cylinder under investigation. Using the experimental method, an axial load up to 15,000 lb is applied to the cylinder using a Landmark 370 MTS unit to generate pressure inside the cylinder wall. Lame´ equations are used to calculate hoop stress theoretically. The numerical data is obtained using finite element simulation (ANSYS) to calculate hoop stress and hoop strain at the internal and external surfaces of the cylinder. This work provides useful information for evaluating the strength of thick-walled cylindrical structures in a laboratory setting.

A Study of the Residual Stress Distribution in an Autofrettaged, Thick-Walled Cylinder With Cross-Bore

2004 ◽  
Vol 126 (4) ◽  
pp. 497-503 ◽  
Author(s):  
Amer Hameed ◽  
R. D. Brown ◽  
John Hetherington
Keyword(s):  
Residual Stress ◽  
Circumferential Stress ◽  
Stress Profile ◽  
Outer Diameter ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Residual Stress Profile ◽  
Gun Barrel ◽  
The Cross ◽  
Walled Cylinder

It may be necessary to provide a radial opening such as gas evacuator holes, or an opening to operate the unlocking of the bolt mechanism by means of exhaust gases, in a gun barrel, which is a thick walled cylinder. A three dimensional finite element analysis has been performed to evaluate the effect of introducing a radial cross-bore in an autofrettaged thick-walled cylinder. From the analysis of the cross-bored autofrettaged cylinder, it was observed that there is a severe localized change in the residual stress profile in the vicinity of the cross-bore. The residual circumferential stress increases in compression at the bore. Similarly it increases in tension at the outer diameter, thus making the outer diameter more vulnerable to fatigue failure or crack initiation under stresses arising as a result of firing. Analyses were also performed by varying the cross-bore diameter and it was observed that, by increasing the diameter of the radial hole, the residual circumferential stress at the bore reduces, while it increases at the outer diameter, with an increase in the cross bore diameter. The re-pressurization pressure of an autofrettaged cylinder with radial cross-bore was found to be approximately 65 percent less than the actual autofrettage pressure in a particular case discussed in this paper. A comparison is also made with the residual stress field which would result if the cross-bore was machined before autofrettage.

The Effects of the Material's Exact Yield Point and Its Plastic Properties on the Safe Maximum Pressure of Gun Barrels

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
J. Perry ◽  
M. Perl
Keyword(s):  
Yield Stress ◽  
Bauschinger Effect ◽  
Strain Curve ◽  
Detailed Comparison ◽  
Maximum Pressure ◽  
Residual Stress Field ◽  
Transition Range ◽  
Plastic Properties ◽  
Gun Barrel ◽  
Zero Offset

The design of a gun barrel aims at maximizing its firing power, determined by its safe maximum pressure (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 3D computer code has been developed, which finally enables a realistic simulation of both swage and hydraulic autofrettage processes, using the experimentally measured stress–strain curve and incorporating the Bauschinger effect. This code enables a detailed analysis of all the factors relating to the final SMP of a barrel and 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 both tension and compression, the Bauschinger effect factor (BEF) curve, and the elastic–plastic transition range (EPTR). A detailed comparison between three similar barrel 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 other four parameters are found to have a greater influence on the SMP of a hydraulically autofrettaged barrel than on a swaged one. The simplicity of determining the zero offset yield stress will enable its use in any common elastic and elastoplastic problem instead of the present 0.1% or 0.2% yield stress methods.

3D Finite Element Simulation of Hard Turning

2009 ◽  
Vol 69-70 ◽  
pp. 11-15 ◽  
Author(s):  
Cai Xu Yue ◽  
Xian Li Liu ◽  
Dong Kai Jia ◽  
Shu Yi Ji ◽  
Yuan Sheng Zhai
Keyword(s):  
Shear Failure ◽  
Cutting Temperature ◽  
Failure Criteria ◽  
Cutting Process ◽  
Cutting Condition ◽  
Residual Stress Field ◽  
Surface Residual Stress ◽  
Element Simulation ◽  
Side Flow ◽  
Hard Cutting

A 3D model is established in this paper to simulate cutting process of PCBN tool cylindrical cutting hardened steel GCr15 using ABAQUS/Explicit. The model effectively overcomes serious element distortions and cell singularity in high strain domain caused by material large deformation by adopting shear failure criteria and element deletion criteria. In this study cutting force, cutting temperature, surface residual stress field as well as side flow are forecasted of hard cutting process with chamfering tool preparation. It shows that satisfactory results could be obtained by FEM. The simulation results provide theoretical basis for studying hard cutting mechanism and selecting the best cutting condition in practical.

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