Effect of Yield Criterion on Stress Distribution and Maximum Safe Pressure for an Autofrettaged Gun Barrel

2017 ◽  
Vol 67 (5) ◽  
pp. 504
Author(s):  
Amit Bhetiwal ◽  
Sunil Kashikar ◽  
Haribhau Markale ◽  
Shailendra Gade
Keyword(s):  
Stress Distribution ◽  
Yield Criterion ◽  
The Other ◽  
Uniform Thickness ◽  
Theoretical Weight ◽  
Gun Barrel ◽  
Von Mises Criterion ◽  
Tresca Criterion ◽  
Von Mises

<p>World artillery in the present scenario is changing its role from defensive to aggressive nature and is attempting to achieve higher penetration into enemy targets. Even for an autofrettaged gun barrel, higher ranges requirement leads to higher barrel weight and its associated demerits. The design of gun barrel is based on the choice of yield criteria. Tresca yield criterion provides conservative design for a ductile barrel material. On the other hand, more accurate von Mises criterion presents complexity. The two criteria to evaluate various parameters required for design of an autofrettaged gun barrel are compared. The methodology for evaluation of maximum safe pressure, based on von Mises criterion, for an autofrettaged gun barrel is also included in the paper. Based on case study included in the article, for an autofrettaged gun barrel or pressure vessel with uniform thickness, a theoretical weight reduction of approximately 16 per cent is feasible with von Mises criterion as compared to Tresca criterion.</p>

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.

Stress Distribution Around Two Dental Implant Materials with New Designs: Comparative Finite Element Analysis Study

2021 ◽  
Vol 4 (1) ◽  
pp. 19
Author(s):  
Faaiz Alhamdani ◽  
Khawla H. Rasheed ◽  
Amjed Mahdi
Keyword(s):  
Stress Distribution ◽  
Dental Implant ◽  
Cancellous Bone ◽  
Stress Level ◽  
The Other ◽  
Von Mises Stress ◽  
Uniform Stress ◽  
Element Analysis ◽  
Other Hand ◽  
Von Mises

Background: The introduction of modified thread designs is one of the research areas of interest in the dental implantology field. Two suggested Buttress and Reverse Buttress thread designs in TiG5 and TiG4 models are tested against a standard TiG5 Fin Thread design (IBS®). Purpose: The study aims to compare stress distribution around the suggested designs and Fin Thread design. Methods: Three dental implant models: Fin Thread design, and newly suggested Buttress and Reverse Buttress designs of both TiG5 and TiG4 models were tested using FEA for stress distribution using static (70N, 0°) and (400N, 30°) occlusal loads. Results: The main difference between the suggested Buttress design and Fin Thread design lies in the overload (400N, 30°) condition. Maximum Von Mises stress is less in Buttress design than Fin Thread design. On the other hand the level of Von Mises stress over the buccolingual slop of the cancellous bone in Fin Thread design liess within the lowest stress level. The suggested Reverse Buttress design, on the other hand showed almost uniform stress distribution in both TiG4 and TiG4 models with maximum Von Mises stress higher than the elastic modulus of cancellous bone in overload (400N, 30°) condition. Conclusion: The suggested TiG4 Buttress design might have a minor advantage of stress level in cases of stress overload. In contrast, Fin Thread design shows minimal stress over the buccolingual slop of the cancellous bone. The suggested Reverse Buttress design might be more suitable for the D1 bone quality region with the advantage of almost uniform stress distribution

Evaluation of Burst Pressure of Corroded Pipe Segments Using Three-Dimensional Finite Element Analyses

2018 ◽  
Author(s):  
Ji Bao ◽  
Shulong Zhang ◽  
Wenxing Zhou ◽  
Shenwei Zhang
Keyword(s):  
Finite Element ◽  
Yield Criterion ◽  
Three Dimensional ◽  
Full Scale ◽  
Burst Pressure ◽  
Dimensional Finite Element ◽  
Tresca Criterion ◽  
Von Mises ◽  
Three Dimensional Finite Element ◽  
The Impact

In this paper, three-dimensional finite element models are developed to simulate full-scale burst tests of corroded pipes containing multiple naturally occurring corrosion anomalies. Both the von Mises and Tresca yield criteria and associated flow rules are employed in finite element analysis (FEA). For the Tresca criterion, the corresponding constitutive model subroutine is developed and incorporated in the FEA. The accuracy of FEA is investigated by comparing the burst pressures observed in the tests and corresponding burst pressures predicted using FEA. The implications of using the von Mises and Tresca criteria for the accuracy of the predicted burst pressure are investigated. Sensitivity analyses are also carried out to investigate the impact on the predicted burst pressure due to the mesh density in the corroded region, characterization of the geometry of the corrosion cluster and different types of element (e.g. solid and shell elements) used in FEA. The results suggest that the Tresca criterion always underestimates the burst pressure and the von Mises yield criterion predicts the burst pressure accurately. This study demonstrates the feasibility of using high-fidelity FEA and the Tresca yield criterion to simulate full-scale burst tests of corroded pipes and therefore establish a large database of burst pressure capacities of corroded pipes that can be used to develop an accurate, practical burst pressure capacity model amenable to the pipeline integrity management practice.

Stresses in torispherical drumheads: A photoelastic investigation

1965 ◽  
Vol 1 (1) ◽  
pp. 69-82 ◽  
Author(s):  
H Fessler ◽  
P Stanley
Keyword(s):  
Stress Concentration ◽  
Stress Distribution ◽  
Elastic Stress ◽  
Yield Criterion ◽  
Uniform Stress ◽  
Stress Indices ◽  
Wide Range ◽  
Photoelastic Investigation ◽  
Bending Stresses ◽  
Von Mises

The dependence of the elastic stress distribution on the shape and thickness parameters in a wide range of torispherical drumheads has been examined using the photoelastic frozen-stress method. Peak principal stress indices are presented in the form of two contour systems; they have also been studied in terms of mean and bending stresses. An approximate approach to some of the practical problems of non-uniform stress gradients is suggested. Head distortions have been measured. A stress concentration factor based on the Maxwell-von Mises yield criterion is shown to be approximately equal to the conventional one.

Effect of Pressure-Dependency of the Yield Criterion on the Development of Plastic Zones and the Distribution of Residual Stresses in Thin Annular Disks

2011 ◽  
Vol 78 (3) ◽  
Author(s):  
Sergei Alexandrov ◽  
Yeau-Ren Jeng ◽  
Evgenii Lomakin
Keyword(s):  
Stress Distribution ◽  
Residual Stresses ◽  
Yield Criterion ◽  
Circumferential Stress ◽  
The Other ◽  
Plastic Yielding ◽  
Annular Disk ◽  
Effect Of Pressure ◽  
Other Hand ◽  
Pressure Dependency

The main objective of the present paper is to show an effect of pressure-dependency of the yield criterion on the development of the plastic zone and the distribution of residual stresses in a thin annular disk subject to a pressure over its inner edge during the loading stage. The Drucker–Prager yield criterion is adopted to account for the effect of the hydrostatic pressure on plastic yielding. The state of stress is supposed to be plane and the material model is perfectly plastic. A semi-analytical stress solution to the problem formulated is given and its qualitative features are emphasized. It is shown that the pressure at which plastic yielding starts and the pressure at which the entire disk becomes plastic are weakly affected by the pressure-dependency of the yield criterion. On the other hand, this dependency has a significant effect on the maximum possible pressure that can be supported by the disk. The minimum pressure at which reverse yielding occurs is also affected by the pressure-dependency of the yield criterion. In general, the residual radial stress distribution is more influenced by the pressure-dependency of the yield criterion than the residual circumferential stress distribution, although the magnitude of circumferential stresses is larger than the magnitude of radial stresses. On the other hand, the effect of pressure-dependency of the yield criterion on the residual circumferential stress distribution is pronounced in the vicinity of the inner edge of the disk, where this stress is important for improving fatigue performance of structures.

Geometric and Material Nonlinear Analyses of a Heated Zigzag Pipeline: Case Study to Look for High Stress Situations

2006 ◽  
Author(s):  
Adilson Carvalho Benjamin ◽  
Rita de Ca´ssia Carvalho Silva ◽  
Joa˜o Nisan Correia Guerreiro ◽  
Abimael Fernando Dourado Loula
Keyword(s):  
Yield Criterion ◽  
High Stress ◽  
General Purpose ◽  
Isotropic Hardening ◽  
Plasticity Model ◽  
Nonlinear Analyses ◽  
Hardening Rule ◽  
Von Mises ◽  
Material Nonlinear

This paper describes the case study performed to look for high stress situations that may occur along the life span of a heated zigzag pipeline. The main results of several finite element (FE) analyses are presented. These analyses were performed using the general purpose FE program ABAQUS considering geometric and material nonlinearities. A rate-independent plasticity model using the von Mises yield criterion and isotropic hardening rule were adopted.

A note on the yielding of an accelerating, non-homogeneous disc of varying thickness and density with radial loading

1978 ◽  
Vol 13 (1) ◽  
pp. 59-63
Author(s):  
G V Gurushankar
Keyword(s):  
Uniform Density ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Uniform Thickness ◽  
Varying Thickness ◽  
Von Mises Criterion ◽  
Yield Loci ◽  
Von Mises ◽  
Radial Loading ◽  
Special Case

The influences of non-homogeneity and density on the normal stresses and shear stresses developed due to the acceleration of a disc, of varying thickness, at any particular instant, are analysed. Yield loci, on the basis of von Mises' criterion, are found for discs of varying thickness and uniform thickness with a bore ratio ( a/ b) of 0.25 and also for linearly varying ( p = 1.0, q = 1.0) and nonlinearly varying ( p = 0.5, q = 0.5) density and homogeneity. A homogeneous, uniform density and uniform thickness disc forms a special case of the analysis.

Biomechanical Evaluation of an Endplate-Conformed Polycaprolactone-Hydroxyapatite Intervertebral Fusion Graft and Its Comparison With a Typical Nonconformed Cortical Graft

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Aakash Agarwal ◽  
Vivek Palepu ◽  
Anand K. Agarwal ◽  
Vijay K. Goel ◽  
Eda D. Yildirim
Keyword(s):  
Stress Distribution ◽  
Case Studies ◽  
Posterior Instrumentation ◽  
Von Mises Stress ◽  
Fe Model ◽  
Stress Distributions ◽  
Functional Spinal Unit ◽  
Thoracolumbar Region ◽  
Von Mises

In the thoracolumbar region, between 7% and 30% of spinal fusion failures are at risk for pseudarthrosis. From a biomechanical perspective, the nonconformity of the intervertebral graft to the endplate surface could contribute to pseudarthrosis, given suboptimal stress distributions. The objective of this study was to quantify the effect of endplate-graft conformation on endplate stress distribution, maximum Von Mises stress development, and stability. The study design used an experimentally validated finite element (FE) model of the L4–L5 functional spinal unit to simulate two types of interbody grafts (cortical bone and polycaprolactone (PCL)-hydroxyapatite (HA) graft), with and without endplate-conformed surfaces. Two case studies were completed. In Case Study I, the endplate-conformed grafts and nonconformed grafts were compared under without posterior instrumentation condition, while in Case Study II, the endplate-conformed and nonconformed grafts were compared with posterior instrumentation. In both case studies, the results suggested that the increased endplate-graft conformity reduced the maximum stress on the endplate, created uniform stress distribution on endplate surfaces, and reduced the range of motion of L4–L5 segments by increasing the contact surface area between the graft and the endplate. The stress distributions in the endplate suggest that the load sharing is greater with the endplate-conformed PCL-HA graft, which might reduce the graft subsidence possibility.

Development and regional planning within the decentralized administrative frame: case study (the Jordanian Experiment)

2018 ◽  
Vol 1 (2) ◽  
pp. 60-72
Author(s):  
Mansour Safran
Keyword(s):  
Regional Planning ◽  
The Other ◽  
Negative Effects ◽  
Administrative Procedures ◽  
The Way

This aims to review and analyze the Jordanian experiment in the developmental regional planning field within the decentralized managerial methods, which is considered one of the primary basic provisions for applying and success of this kind of planning. The study shoed that Jordan has passed important steps in the way for implanting the decentralized administration, but these steps are still not enough to established the effective and active regional planning. The study reveled that there are many problems facing the decentralized regional planning in Jordan, despite of the clear goals that this planning is trying to achieve. These problems have resulted from the existing relationship between the decentralized administration process’ dimensions from one side, and between its levels which ranged from weak to medium decentralization from the other side, In spite of the official trends aiming at applying more of the decentralized administrative policies, still high portion of these procedures are theoretical, did not yet find a way to reality. Because any progress or success at the level of applying the decentralized administrative policies doubtless means greater effectiveness and influence on the development regional planning in life of the residents in the kingdom’s different regions. So, it is important to go a head in applying more steps and decentralized administrative procedures, gradually and continuously to guarantee the control over any negative effects that might result from Appling this kind of systems.   © 2018 JASET, International Scholars and Researchers Association

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