Determination of All Stress Components of Axisymmetric Stress State in Photoelastic Tomography

2011 ◽  
Vol 70 ◽  
pp. 434-439
Author(s):  
Andrei Errapart
Keyword(s):  
Stress State ◽  
Residual Stresses ◽  
Direct Determination ◽  
Hertzian Contact ◽  
Axisymmetric Stress State ◽  
Positive Direction ◽  
Stress Components ◽  
Hertzian Contact Stress ◽  
Basic Equations ◽  
External Loads

In this paper we describe the application of photoelastic tomography for determining stresses in glass. The basic equations of linear approximation in photoelastic tomography are presented. Since these equations permit direct determination only of the axial and shear stress, a method for calculating the other stress components is described. In the case of the residual stresses, it uses the equilibrium equation and the generalized sum rule. In the case of stresses due to external loads, it uses the equilibrium and compatibility equations. It is shown, both graphically and analytically, that integration of these equations must start at the axis and proceed along the positive direction of the radial axis. As an example, residual stresses in the stem of a wine glass are determined. Results are verified by comparing the birefringence, calculated from the determined stress state, with measured birefringence. The numerical algorithm for the case of stresses due to external loads is verified by using the theoretical solution for a Hertzian contact stress problem.

Surface Durability of Spur Gears at Hertzian Stresses Over Shakedown Limit

1974 ◽  
Vol 96 (2) ◽  
pp. 359-372 ◽  
Author(s):  
Akira Ishibashi ◽  
Taku Ueno ◽  
Shigetada Tanaka
Keyword(s):  
Fatigue Testing ◽  
Testing Machine ◽  
Carbon Steels ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Load Testing ◽  
Short Period ◽  
Hertzian Contact Stress ◽  
Surface Durability ◽  
Shakedown Limit

Using a new type of gear-load testing machine and a disk-type rolling fatigue testing machine designed and made by the authors, the upper limits of Hertzian contact stress allowable on rolling contact surfaces were investigated. It was shown conclusively that gears and rollers made of soft carbon steels could be rotated beyond 108 revolutions at Hertzian stresses over shakedown limit (≈ 0.4 HB). In the case of gears, pits having a pitting area ratio of 0.04 percent occurred during 1.16 × 108 rotations at a Hertzian stress of 0.50 HB. However, no pitting occurred on the roller rotated through 1.20 × 108 revolutions at a Hertzian stress of 0.71 HB, although appreciable changes in texture were observed at the subsurface. In order to rotate gears or rollers at Hertzian stresses over shakedown limit, their surface must either be very smooth initially or after a short period of running, and an oil film must be formed between contacting surfaces.

Deformation distortions of geometric form tube blanks in the process of drilling holes

2021 ◽  
pp. 104-110
Author(s):  
A.N. Isaev ◽  
S.V. Vlaskin ◽  
V.A. Lebedev ◽  
M.D. Gavrilenko
Keyword(s):  
Stress State ◽  
Wall Thickness ◽  
Cross Sections ◽  
Theoretical Studies ◽  
Geometric Form ◽  
Axisymmetric Stress ◽  
Axisymmetric Stress State ◽  
Elastic Plastic ◽  
The Cross

The influence of deviations of the shape of the cross-sections of pipes from roundness on the axisymmetric stress state and taking this factor into account in theoretical studies and methods for solving problems of mandrel drilling in the elastic-plastic mode are considered. The features of the choice of tubular blanks, which help to reduce the unevenness of deformation and increase the accuracy of processing in the process of mandrel drilling, are revealed. Recommendations are given for eliminating the variance in wall thickness of blanks at the stage of their preparation for the mandrel operation.

About Residual Stress State of Castings: The Case of HPDC Parts and Possible Advantages through Semi-Solid Processes

2022 ◽  
Vol 327 ◽  
pp. 272-278
Author(s):  
Elisa Fracchia ◽  
Federico Simone Gobber ◽  
Claudio Mus ◽  
Yuji Kobayashi ◽  
Mario Rosso
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Casting Process ◽  
Ray Method ◽  
Premature Failure ◽  
Thin Walls ◽  
Residual Stress State ◽  
Semi Solid ◽  
Pressure Die Casting

Nowadays, one of the most crucial focus in the aluminium-foundry sector is the production of high-quality castings. Mainly, High-Pressure Die Casting (HPDC) is broadly adopted, since by this process is possible to realize aluminium castings with thin walls and high specific mechanical properties. On the other hand, this casting process may cause tensile states into the castings, namely residual stresses. Residual stresses may strongly affect the life of the product causing premature failure of the casting. Various methods can assess these tensile states, but the non-destructive X-Ray method is the most commonly adopted. Namely, in this work, the residual stress analysis has been performed through Sinto-Pulstec μ-X360s. Detailed measurements have been done on powertrain components realized in aluminium alloy EN AC 46000 through HPDC processes to understand and prevent dangerous residual stress state into the aluminium castings. Furthermore, a comparison with stresses induced by Rheocasting processes is underway. In fact, it is well known that Semi-Solid metal forming combines the advantages of casting and forging, solving safety and environmental problems and possibly even the residual stress state can be positively affected.

A Simple Approach for Including Weld Residual Stresses in the Calculation of Pipe Circumferential Through-Wall Crack Opening Displacements

2016 ◽  
Author(s):  
Richard Olson
Keyword(s):  
Residual Stresses ◽  
Axial Force ◽  
Analytic Solution ◽  
Crack Opening ◽  
Bending Moment ◽  
Generalized Solution ◽  
Finite Element Analyses ◽  
Opening Displacement ◽  
Crack Face ◽  
Basic Equations

Current methodologies for predicting the crack opening displacement (COD) of circumferentially through-wall cracked pipe do not include the effect of weld residual stresses (WRS). Even the most advanced COD prediction methodology only includes the effect of applied axial force, bending moment, and crack face pressure. For some years, it has been known that weld residual stresses do alter the COD, but there has been no convenient way to include them in a COD prediction without doing case-specific finite element analyses. This paper documents a generalized solution for including WRS effects on COD. The model uses a closed-form analytic solution to approximate the crack face rotations that the WRS would induce which, subsequently, can be added to the typical axial force-bending-crack face pressure COD solution. The methodology is described and the basic equations for the solution are presented. Following this, application to cases to evaluate the efficacy of the approach are presented which show a mixture of results ranging from amazingly good to “of questionable value” with respect to the FEA results.

Analysis of Residual Stresses in a Polymer Cylinder when it is Stopped and then Cooled in a Nonlinear and Linearized Problem Settings

2021 ◽  
Vol 899 ◽  
pp. 486-492
Author(s):  
Liubov I. Lesnyak ◽  
Vladimir I. Andreev ◽  
Serdar B. Yazyev ◽  
Arthur A. Avakov ◽  
Irina G. Doronkina
Keyword(s):  
Stress State ◽  
Residual Stresses ◽  
The Body ◽  
Linearized Problem ◽  
Deformed State ◽  
Problem Setting

In conclusion, one should say that, to determine the approximate stress state in the body, it is quite enough to consider the problem in a linearized problem setting. When determining the deformed state, it is necessary to consider the problem exclusively in a nonlinear setting.

Residual Stresses of Round Steel Rod at Elastoplastic Twisting

2020 ◽  
Vol 989 ◽  
pp. 642-646
Author(s):  
Vladimir N. Shinkin
Keyword(s):  
Residual Stresses ◽  
Cross Section ◽  
Pure Shear ◽  
Rupture Surface ◽  
Elastic Zone ◽  
Plastic Materials ◽  
Hardening Modulus ◽  
Screw Surface ◽  
Residual Deformations ◽  
External Loads

In the elastoplastic twisting of a rod under the action of an external torque, the cross-section of the rod is divided into two zones: the inner elastic zone and the outer plastic zone. After removing the external loads, we observe the residual deformations and the residual stresses inside the rod that significantly affect on the subsequent mechanical processes at manufacturing the products from the round rod. Under too much twisting, the longitudinal surface fibers of the rod begin to tear, the outer surface of the rod ceases to be cylindrical, and the rod’s cross-section ceases to be flat (the Bernoulli’s hypothesis about the flat sections is violated). Next a rupture of the rod is followed. For the plastic materials, the destruction is caused by the pure shear, and the rupture surface is perpendicular to the axis of the rod. For the brittle materials, the destruction occurs, due to the rupture along the screw surface inclined to the axis of the round rod at the angle of 45. In this paper, the residual stresses of the round rod at twisting are obtained for an elastoplastic medium with linear hardening in depending on the rod’s diameter, the shear modulus, the hardening modulus in shear and the yield strength in shear of the rod’s material.

Investigation of Welded Joints Made of Construction Steel by the Barkhausen Noise Method

2020 ◽  
Vol 992 ◽  
pp. 957-963
Author(s):  
E. Nikolaeva ◽  
A. Nikolaev
Keyword(s):  
Stress State ◽  
Residual Stresses ◽  
Welded Joints ◽  
Arc Welding ◽  
Barkhausen Noise ◽  
Low Carbon ◽  
Butt Weld ◽  
Welded Structures ◽  
The Relationship ◽  
Weld Seams

Steel weld seams are characterized by heterogeneity of their microstructure. Microstructure affects the nature of the distribution, sign and magnitude of residual stresses. In combination with unfavorable factors (low temperature, metal hypoductility and an unsuccessful joint form) residual stresses lead to a decrease of load carrying capacity of a whole structure. In a weld seam residual stresses are distributed in a complex way and can affect the build quality of heavy section welded structures. Monitoring of residual stresses remains a big problem. Residual stresses in welds are often evaluated only by modeling. Unfortunately, all mathematical models describe the stress state of the welded material with low accuracy. Simple quality control, the results of which can be easy interpreted, is necessary. Welded joints made by manual arc welding and by automatic submerged arc welding were investigated. Butt seams of steel sheets of different thickness have been welded. Steel was low-carbon and low-alloyed. It is often used in welded structures for various purposes, including construction, and for pipelines manufacture. The temperature range of welded structures operation is very large – from-70 to 450С. The authors studied the structure of butt weld seams by the Barkhausen noise method, which is interesting as it represents an alternative to the known methods, which characterizes the structure and stress state of material. The relationship between the weld microstructure and magnetic noise is shown. Studies have allowed us to establish the relationship between the structure and magnetic properties and to evaluate the feasibility of applying the Barkhausen noise method to welded structures.

Effect of Lubricant on Surface Rolling Contact Fatigue Cracks

2010 ◽  
Vol 97-101 ◽  
pp. 793-796 ◽  
Author(s):  
Khalil Farhangdoost ◽  
Mohammad Kavoosi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Element Analysis ◽  
Crack Face ◽  
Hertzian Contact Stress ◽  
Model Of Friction

This study performed the finite element analysis of the cycle of stress intensity factors at the surface initiated rolling contact fatigue crack tip under Hertzian contact stress including an accurate model of friction between the faces of the crack and the effect of fluid inside the crack. A two-dimensional model of a rolling contact fatigue crack has been developed with FRANC-2D software. The model includes the effect of Coulomb friction between the faces of the crack. The fluid in the crack was assumed not only to lubricate the crack faces and reduce the crack face friction coefficient but also to generate a pressure.

Fundamentals of Residual Stresses in Joints Between Dissimilar Materials

MRS Bulletin ◽  
1995 ◽  
Vol 20 (1) ◽  
pp. 37-39 ◽  
Author(s):  
B.H. Rabin ◽  
R.L. Williamson ◽  
S. Suresh
Keyword(s):  
Residual Stresses ◽  
Material Properties ◽  
Critical Stress ◽  
Failure Mechanisms ◽  
Dissimilar Materials ◽  
Free Edge ◽  
Structural Components ◽  
Failure Characteristics ◽  
Stress Components ◽  
Metal Joint

When a discontinuity in material properties exists across a bonded interface, stresses are generated as a result of any thermal or mechanical loading. These stresses significantly affect strength and failure characteristics and may be large enough to prevent successful fabrication of a reliable joint. The use of an interlayer material to successfully reduce mismatch stresses, thereby preventing joint failure or improving joint strength and reliability, requires knowledge of failure mechanisms and of the effects of interlayer properties on the critical stress components.The origin of residual stresses developed during cooling of a ceramic-metal joint from an elevated fabrication temperature is illustrated qualitatively in Figure 1. Away from edges, the in-plane (parallel to interface) stresses are typically compressive in the ceramic and tensile in the metal. These stresses can cause cracking perpendicular to the interface, leading to spalling or delamination failures. Such failures are frequently observed in thin-film and coating geometries. Where the interface intersects a free edge, large shear and axial (perpendicular to the interface) stresses are generated. The edge stresses are typically tensile within the ceramic and tend to promote crack propagation within the ceramic parallel and adjacent to the interface. This is the most commonly observed failure mode in bonded structural components.

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