The Experts below are selected from a list of 12033 Experts worldwide ranked by ideXlab platform
E Niemi - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the Stress Concentration Factor for a shallow notch by the slip-line field method
International Journal of Fatigue, 1997Co-Authors: M. Zheng, E NiemiAbstract:The relationships correlating the local Stress and strain at the tip of a notch, the nominal Stress expressed by the so called Neuber's rule and Moski and Glinka's equivalent energy density method are studied for a shallow notch,using the slip-line field method proposed in plastic mechanics, and an elastic-plastic solution for the area close to the notch. An elastic-perfect plastic material model is also used. It is found that for lower Stress amplitude Moski and Glinka's method is with a good accuracy; however, the relative deviations of the actual Stress Concentration Factors calculated by these two methods to the theoretical Stress Concentration Factor are not small, even up to 20% for higher Stress amplitude as the size of the plastic zone around the notch approaches the value of the radius of the notch curvature. While the geometric mean of the two expressions mentioned above can be considered as a reasonable expression to correlate the local Stress-strain and the nominal Stress, and thus the corresponding actual equivalent Stress Concentration Factor can be evaluated, of which the relative deviations to the theoretical Stress Concentration Factor is shown to be
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analysis of the Stress Concentration Factor for a shallow notch by the slip line field method
International Journal of Fatigue, 1997Co-Authors: M. Zheng, E NiemiAbstract:The relationships correlating the local Stress and strain at the tip of a notch, the nominal Stress expressed by the so called Neuber's rule and Moski and Glinka's equivalent energy density method are studied for a shallow notch,using the slip-line field method proposed in plastic mechanics, and an elastic-plastic solution for the area close to the notch. An elastic-perfect plastic material model is also used. It is found that for lower Stress amplitude Moski and Glinka's method is with a good accuracy; however, the relative deviations of the actual Stress Concentration Factors calculated by these two methods to the theoretical Stress Concentration Factor are not small, even up to 20% for higher Stress amplitude as the size of the plastic zone around the notch approaches the value of the radius of the notch curvature. While the geometric mean of the two expressions mentioned above can be considered as a reasonable expression to correlate the local Stress-strain and the nominal Stress, and thus the corresponding actual equivalent Stress Concentration Factor can be evaluated, of which the relative deviations to the theoretical Stress Concentration Factor is shown to be <5%, if the size of plastic zone close to the notch is not greater than the value of the radius of curvature of the notch.
Z Azari - One of the best experts on this subject based on the ideXlab platform.
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Stress Concentration Factor analysis for welded notched tubular t joints under combined axial bending and dynamic loading
International Journal of Fatigue, 2009Co-Authors: A Ndiaye, S Hariri, G Pluvinage, Z AzariAbstract:The finite element analysis will be used in this study to predict the location of hot-spot Stresses in a welded tubular T-joint. The fillet weld has been modeled all around the joint. Using symmetry, the tubular T-joint is submitted to axial, in-plane bending (IPB) and out-of-plane bending (OPB) loadings. The finite element method analysis shows that Stresses are very high on the brace member in the vicinity of the fillet weld and gradually decrease, with a quasi-stable difference, in the direction of the brace extremity. Both on the brace member and along the fillet weld (from crown to saddle), Stresses are high at the crown toe, decrease in the middle and increase once again at the saddle point. From a general perspective, this Stress distribution analysis reveals that hot-spot Stresses (HSS) are located at the crown and saddle points. Dynamic loading greatly increases the Stress Concentration Factor at the hot-spot Stress (HSS) located on the brace member where fatigue damage is capable of appearing quickly. In the U-notch, this Stress Concentration Factor (SCF) increases as notch width decreases. In a general way therefore, Stress Concentration Factors decrease on the brace and chord members (in the vicinity of the weld) and increase considerably in the notch, which underscores the deleterious nature of such a defect. Consequently, these zones (HSS) require reinforcement solutions in order to ensure a sufficiently long fatigue life for offshore structures.
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Stress Concentration Factor analysis for notched welded tubular t joints
International Journal of Fatigue, 2007Co-Authors: A Ndiaye, S Hariri, G Pluvinage, Z AzariAbstract:In this study, the finite element method (FEM) is applied on a welded tubular T-joint, in order to analyse Stress distribution in the vicinity of the weld fillet. The weld has been modelled all around the joint. A notch is to be simulated in the weld element, all around the joint as well. Using symmetry, the tubular T-joint is submitted to three loading cases: axial loading, in-plane bending (IPB), and out-of-plane bending (OPB). The Stress distribution analysis, conducted using the (ARSEM, API, RP2A) code, has enabled locating the peak hot-spot Stresses. The finite element method analysis shows that Stresses are very high on the brace member, in the vicinity of the weld, and decrease gradually, with a quasi-stable difference, in the direction of the brace extremity. Both on the brace member and along the weld (from crown to saddle), the Stresses are high at the crown toe, decrease in the middle and increase once again at the saddle point. Consequently, these zones are susceptible to fatigue damage and require reinforcement solutions in order to ensure sufficiently-long fatigue life for tubular T-joints. For the V-notch, the Stress intensity Factor at the notch is the parameter selected when processing crack-related problems. Stress distribution from the notch bottom towards the load-bearing segment indicates that the Stress intensity Factor rises as the radius increases at the notch bottom. The Stress Concentration Factor is higher in the bottom of the notched weld at the load-bearing segment, which in most instances causes crack problems with an increase in Stress intensity Factor; this finding explains the harmful character of such defects and reveals the extent to which the presence of a notch in a weld fillet lowers the resistance of offshore structures to fatigue cracks.
Jie Yu - One of the best experts on this subject based on the ideXlab platform.
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effect of characteristic parameters of pitting on strength and Stress Concentration Factor of cable steel wire
Construction and Building Materials, 2020Co-Authors: Rou Li, Changqing Miao, Jie YuAbstract:Abstract In order to investigate the influence of characteristic parameters of pits on the strength and Stress Concentration Factor of cable steel wire, 198 cable steel wires with pits were manually prepared. The variation law of Stress distribution of steel wire was analyzed, and its relationships with strength and Stress Concentration Factor were studied through tensile test and finite element analysis. On this basis, the calculation model of yield strength and Stress Concentration Factor of steel wire with pits was established. The influences of secondary pits on Stress distribution and Stress Concentration Factor of steel wire were also analyzed. The results showed that the strength of steel wire decreased gradually and the Stress Concentration Factor increased with the increase of pit depth and the decrease of pit width. The change of pit clearance on the same side had no obvious effect on the strength and Stress Concentration Factor of steel wire, but it had significant effect when located on the opposite side. The strength and Stress Concentration Factor of steel wire with adjacent pits usually depended on the depth of the larger pits. The pits with depth to width ratio of 1 to 2 had the most significant effect on the Stress Concentration Factor. Moreover, secondary pit would change the Stress distribution, and the position of maximum Stress changed from near the mouth to the bottom of the pit. The Stress Concentration Factor of secondary pit was obviously higher than that of steel wire with only the primary pit.
M. Zheng - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the Stress Concentration Factor for a shallow notch by the slip-line field method
International Journal of Fatigue, 1997Co-Authors: M. Zheng, E NiemiAbstract:The relationships correlating the local Stress and strain at the tip of a notch, the nominal Stress expressed by the so called Neuber's rule and Moski and Glinka's equivalent energy density method are studied for a shallow notch,using the slip-line field method proposed in plastic mechanics, and an elastic-plastic solution for the area close to the notch. An elastic-perfect plastic material model is also used. It is found that for lower Stress amplitude Moski and Glinka's method is with a good accuracy; however, the relative deviations of the actual Stress Concentration Factors calculated by these two methods to the theoretical Stress Concentration Factor are not small, even up to 20% for higher Stress amplitude as the size of the plastic zone around the notch approaches the value of the radius of the notch curvature. While the geometric mean of the two expressions mentioned above can be considered as a reasonable expression to correlate the local Stress-strain and the nominal Stress, and thus the corresponding actual equivalent Stress Concentration Factor can be evaluated, of which the relative deviations to the theoretical Stress Concentration Factor is shown to be
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analysis of the Stress Concentration Factor for a shallow notch by the slip line field method
International Journal of Fatigue, 1997Co-Authors: M. Zheng, E NiemiAbstract:The relationships correlating the local Stress and strain at the tip of a notch, the nominal Stress expressed by the so called Neuber's rule and Moski and Glinka's equivalent energy density method are studied for a shallow notch,using the slip-line field method proposed in plastic mechanics, and an elastic-plastic solution for the area close to the notch. An elastic-perfect plastic material model is also used. It is found that for lower Stress amplitude Moski and Glinka's method is with a good accuracy; however, the relative deviations of the actual Stress Concentration Factors calculated by these two methods to the theoretical Stress Concentration Factor are not small, even up to 20% for higher Stress amplitude as the size of the plastic zone around the notch approaches the value of the radius of the notch curvature. While the geometric mean of the two expressions mentioned above can be considered as a reasonable expression to correlate the local Stress-strain and the nominal Stress, and thus the corresponding actual equivalent Stress Concentration Factor can be evaluated, of which the relative deviations to the theoretical Stress Concentration Factor is shown to be <5%, if the size of plastic zone close to the notch is not greater than the value of the radius of curvature of the notch.
Nobuhiro Yoshikawa - One of the best experts on this subject based on the ideXlab platform.
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empirical formulation of Stress Concentration Factor around an arbitrary sized spherical dual cavity system and its application to aluminum die castings
Applied Mathematical Modelling, 2015Co-Authors: Sujit Bidhar, Osamu Kuwazuru, Yoshinori Shiihara, Takao Utsunomiya, Ikumu Watanabe, M Nomura, Yoshihiko Hangai, Nobuhiro YoshikawaAbstract:Abstract An empirical formula for the Stress Concentration Factor is developed for an unequal-sized cavity pair in an arbitrary orientation. Three-dimensional finite element linear elastic analyses are performed to evaluate the Stress Concentration Factors for different sizes, orientations, and separations of cavities. A suitable mathematical function is chosen to fit the numerical results of the finite element analyses. An application is given for evaluating the maximum Stress Concentration Factor, which governs fatigue crack initiation in aluminum die cast test pieces from an engine block. From the X-ray CT image, the location and geometry of the gas pores are evaluated so as to develop the proposed empirical formula for this actual multi-pore system simplified to a dual spherical pore system. A proof of the formula is shown by comparison with voxel finite element analysis. The proposed empirical formula can be satisFactorily used as a scientific guideline for selecting a casting method for car engine blocks from a fatigue crack initiation perspective.
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practical application of empirical formulation of the Stress Concentration Factor around equally sized dual spherical cavities to aluminum die cast
Applied Mathematical Modelling, 2015Co-Authors: Sujit Bidhar, Osamu Kuwazuru, Yoshinori Shiihara, Takao Utsunomiya, Ikumu Watanabe, Yoshihiko Hangai, Nobuhiro YoshikawaAbstract:Abstract An empirical method is developed for obtaining the Stress Concentration Factor for a pair of equally sized spherical cavities embedded in a large continuum in three-dimensional space. For practical applications such as die-cast materials containing many pores, we construct a simple and robust closed-form equation to evaluate the Stress Concentration Factor considering the interaction between two cavities. The Stress Concentration Factor can be used to evaluate the effect of pores on the material strength and the probable location of pores that will initiate a fatigue crack. Three-dimensional finite element linear elastic analysis was carried out to evaluate the Stress Concentration Factors for arbitrary locations of the two cavities. The effects of the inter-cavity distance and the orientation of the inter-cavity axis with respect to the loading direction on the Stress Concentration Factor are numerically obtained by systematically changing each of these parameters. Two empirical equations are proposed to fit the Stress Concentration Factor data calculated by finite element analysis after considering various boundary conditions from a mechanical standpoint, and the parameters of the empirical formula are obtained by non-linear curve fitting with regression analysis.
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Empirical prediction of Stress Concentration Factor for a pair of spherical cavities
2011 Fourth International Conference on Modeling Simulation and Applied Optimization, 2011Co-Authors: Sujit Bidhar, Takayuki Yano, Osamu Kuwazuru, Takao Utsunomiya, Yoshihiko Hangai, Nobuhiro YoshikawaAbstract:A methodology to evaluate the effect of gas pores on fatigue life of aluminium die casts is proposed in terms of Stress Concentration Factor. As observed in many fatigue tests, it is not always the case that the largest sized pore initiates fatigue crack. So we need to consider the interactions between the gas pores based on their configuration, shapes and sizes. Stress Concentrations around irregular shaped pores play important roles in fatigue crack initiation and consequent fatigue life. In present study, an empirical formulation of elastic Stress Concentration Factor around a pair of spherical shaped cavities is derived by numerical results of three-dimensional finite element linear elastic analyses. The conclusion can be further extended to understand the Stress Concentration around irregular shaped clustered gas pores. The effect of inter-pore distance and orientation of inter-pore axis to loading direction, on Stress Concentration Factor, is obtained numerically by systematically changing each of these parameters. Finally, a suitable function is chosen to fit the Stress Concentration data and its validity is discussed from a mechanical standpoint.