To study the effect of stress magnitude and tool geometry on the calibration coefficients: Ring core technique
01 Dec 2018-Vol. 232, Iss: 6, pp 674-684
TL;DR: In this paper, a ring core technique is used to measure the subsurface residual stresses in component components, and the analytical evaluation of residual stresses by ring core is carried out.
Abstract: Ring core technique is widely used to measure the subsurface residual stresses in components. In the analytical evaluation of residual stresses by ring core technique, the calibration coefficients ...
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TL;DR: In this paper, a method was developed for determining residual stress based on displacement fields near drilled holes analyzed using 3D digital image correlation, which made it possible to determine the residual stress distribution over a wide range of hole depth-to-hole diameter ratios and various areas of displacement field measurements using inverse method iterative calculations.
Abstract: A method has been developed for determining residual stress based on displacement fields near drilled holes analyzed using 3D digital image correlation. Finite element modeling was used to determine corrections for analytical equations describing displacement fields near the blind holes, which made it possible to determine the residual stress distribution over a wide range of hole depth-to-hole diameter ratios and various areas of displacement field measurements using inverse method iterative calculations. The proposed method eliminates many drawbacks of traditional procedure based on strain gauges as hole eccentricity sensitivity and requirement of the relatively large span between holes. The method and testing setup, build-up of generally available components, were used to determine the residual stress distribution for 316 LVM samples processed by two methods from the large deformation group: hydrostatic extrusion (HE) and high-pressure torsion (HPT), by drilling 1.75 and 0.58-mm-diameter blind holes, respectively. In the case of the measurements performed on the surface of a HE-processed 16 mm bar cut along its diameter, a gradual change was revealed—from a compressive to a tensile residual stress distribution (from ~ − 300 MPa in the center to 400 MPa in 4 mm distance from the edge) in the longitudinal direction, with near-zero values in the radial direction. Moreover, the method was also adapted to perform measurements on the outside surface of the bar, which gave results consistent with those taken along the radius profile (~ 600 MPa longitudinal stress). Measurements on the top surface of a cylinder 10 mm in diameter and 1 mm high processed by HPT showed a high compressive residual stress in the center and a dominant shear component for the holes drilled at different distances from the center.
2 citations
TL;DR: In this article , the recent progress of four typical surface strengthening methods is analyzed in detail, including MSP, USP, LSP and BSM, and various research methods and optimization strategies are also compared.
Abstract: Titanium alloys are high-quality materials for aerospace parts with good thermal mechanical properties. Fatigue failure has been the most prominent problem, so surface strengthening technology is widely applied to improve fatigue life. In this paper, the recent progress of four typical strengthening methods is analyzed in detail, including MSP, USP, LSP and BSM. In the strengthening process, the RS induced by PD is the most significant variation, so the basic theory and measurement methods of RS are comprehensively summarized. Besides, grain refinement and dislocation density increase occur simultaneously, as well as the unfriendly phenomenon in the increase of surface roughness. Therefore, the progress in reaction mechanisms, influencing factors, strengthening effects and fatigue improvement of these four typical titanium alloy PD strengthening methods are explained, and various research methods and optimization strategies are summarized. In addition, the differences of strengthening methods are also compared. The latest advances of these methods are described, which will support the progress of strengthening technology.
2 citations
06 Feb 2023-Proceedings Of The Institution Of Mechanical Engineers, Part E: Journal Of Process Mechanical Engineering
TL;DR: In this article , three BSK 46 weldments (weld-1, weld-2 and weld-3) were fabricated by varying the root gap, root face, filler pass and heat input.
Abstract: BSK 46 is a low alloy structural steel with excellent mechanical and corrosion properties and is widely used in many applications, including tipper bodies of heavy-duty trucks. Optimizing the welding parameters to reduce defects and improve productivity is critical for the users. The present work addresses optimizing the welding process parameters to improve productivity with adequate weld quality during the pulsed gas metal arc welding (P-GMAW) process. Three BSK 46 weldments (weld-1, weld-2 and weld-3) were fabricated by varying the root gap, root face, filler pass and heat input. The metallographic and mechanical characterization of P-GMAW weldments were done through microstructures, Vickers micro-hardness, transverse tensile strength, Charpy toughness and three-point bend test. Subsequently, a correlation has been developed between the microstructural features and mechanical properties of the weld joints. The hardness was found to be incremental in nature from the base metal to the fusion zone. Maximum hardness of 215.81 ± 10 HV was observed in the weld-3 fusion zone. Tensile test results reveal that weld-3 weldments exhibit a higher tensile strength of 547.48 ± 2 MPa than weld-1 (537.46 ± 7 MPa) and weld-2 (533.67 ± 9 MPa) weldments. Maximum impact toughness of 136.33 ± 14 J was observed in the weld-3 weldments. Post-bend testing showed no cracks on the weld surfaces, indicating defect-free weld joints with good ductility. It is observed that weld-3 showed relatively better mechanical properties than weld-1 and weld-2 in lesser welding time and lower welding cost
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References
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TL;DR: In this paper, the authors classify different residual stresses measurement methods and provide an overview of some of the recent advances in this area to help researchers on selecting their techniques depending on their application and the availabilities of those techniques.
Abstract: Residual stresses occur in many manufactured structures and components. Large number of investigations have been carried out to study this phenomenon and its effect on the mechanical characteristics of these components. Over the years, different methods have been developed to measure residual stress for different types of components in order to obtain reliable assessment. The various specific methods have evolved over several decades and their practical applications have greatly benefited from the development of complementary technologies, notably in material cutting, full-field deformation measurement techniques, numerical methods and computing power. These complementary technologies have stimulated advances not only in measurement accuracy and reliability, but also in range of application; much greater detail in residual stresses measurement is now available. This paper aims to classify the different residual stresses measurement methods and to provide an overview of some of the recent advances in this area to help researchers on selecting their techniques among destructive, semi destructive and non-destructive techniques depends on their application and the availabilities of those techniques. For each method scope, physical limitation, advantages and disadvantages are summarized. In the end this paper indicates some promising directions for future developments.
633 citations
TL;DR: In this article, the plasticity and stress concentration effects of blind hole drilling technique on the calculation of residual stresses for SS 304L and modified Cr-Mo Grade 91 alloys were investigated experimentally through tensile testing and for biaxial loading through numerical modeling.
Abstract: The blind hole drilling technique, utilized for measuring residual stress by using strain gauge rosette, is associated with plastic deformation of material that is removed from the hole and also with stress concentration effect of multi point cutting tool. Further, the plasticity effect is also induced in presence of high applied stress which may lead to local yielding of the hole boundary. The present paper describes the plasticity and stress concentration effects of blind hole drilling technique on the calculation of residual stresses for SS 304L and modified Cr–Mo Grade 91 alloys. For uniaxial loading, the responses of strain gauge rosettes were investigated experimentally through tensile testing and for biaxial loading through numerical modeling. Correlations were developed to directly calculate the corrected values of residual stresses from the experimental strain data obtained through the strain gauge rosette and from stress values as per ASTM E837-13.
39 citations
"To study the effect of stress magni..." refers background in this paper
...The stresses (ra, rb, and rc) in the grid directions a, b, and c of strain rosette can be described by equations (1) to (3)....
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TL;DR: In this article, a ring-core method/three-dimensional digital image correlation (3D DIC) residual stresses measurement is proposed to determine residual stress and rigid-body motion.
Abstract: Ring-core method/three-dimensional digital image correlation (3D DIC) residual stresses measurement is proposed. Ring-core cutting is a mechanical stress relief method, and combining with 3D DIC system the deformation of the specimen surface can be measured. An optimization iteration method is proposed to obtain the residual stress and rigid-body motion. The method has the ability to cut an annular trench at a different location out of the field of view. A compression test is carried out to demonstrate how residual stress is determined by using 3D DIC system and outfield measurement. The results determined by the approach are in good agreement with the theoretical value. Ring-core/3D DIC has shown its robustness to determine residual stress and can be extended to application in the engineering field.
31 citations
TL;DR: In this article, a 3D finite element (FE) model was used to calculate the residual stress field data at different stress ratios at various depths of the welded joints and this data were used to develop the regression equations as well as to determine the calibration coefficients.
Abstract: Sub surface residual stresses in thick multi-pass stainless steel butt welded joints were measured by dry ring core technique. To accomplish the task of dry ring coring, special tools were developed such that machining induced stresses were negligible. Established equations, analytical methods and regression correlations were used in the measurement. A database of mathematical relations of residual stress values was also developed using the response surface methodology. A 3-D finite element (FE) model was used to prepare the residual stress field data at the different stress ratios at various depths of the welded joints. Further, this data was used to develop the regression equations as well as to determine the calibration coefficients.
30 citations
"To study the effect of stress magni..." refers background or methods in this paper
...regression equations (11) to (14) can be fairly used to evaluate the residual stresses....
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...From the developed regression equations (11) to (14), the residual stresses can be calculated directly from the experimental strain readings obtained during dry ring coring for the tool geometries OD/ID 30/22mm and OD/ID 24/16mm....
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...Respective error in stresses has also been estimated between the applied stresses and the stresses obtained from the mathematical relations as shown in equations (11) to (14)....
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...The developed mathematical relations are depicted as equations (11) to (14) in which equations (11) and (12) represent the ring core geometry OD/ID 30/22mm and equations (13) and (14) represent the ring core geometry OD/ID 24/16mm....
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TL;DR: In this article, the influence of different specimen dimensions on the accuracy of the evaluated residual stresses is considered and the coefficients are used for residual stress evaluation by incremental method used in Ring-Core method.
Abstract: There are several measuring techniques for determining residual stress which can be divided according to the created damage in to the construction in non-destructive, semi-destructive and destructive ones. One of the most common is semi-destructive hole-drilling method. This paper deals about Ring-Core method which is based on the similar principles. Today, there is no standard for the Ring-Core method, thus it is important to consider various influential factors. One of them are the dimensions of specimen. Calibration coefficients are determined by finite element (FE) analysis using the commercial software Solidworks. These coefficients are used for residual stress evaluation by incremental method used in Ring-Core method. The influence of different specimen dimensions on the accuracy of the evaluated residual stresses is considered.
21 citations
"To study the effect of stress magni..." refers background in this paper
...The developed mathematical relations are depicted as equations (11) to (14) in which equations (11) and (12) represent the ring core geometry OD/ID 30/22mm and equations (13) and (14) represent the ring core geometry OD/ID 24/16mm....
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