Papers by Keyword: Stress Concentration Factor (SCF)

Abstract: This paper presents 3-D solid structural modeling and stress analysis of radial nozzle connections in ellipsoidal heads vessel subjected to internal pressure and various external loadings. Finite Element Analysis (FEA) method was utilized to determine the stress distribution at the intersection of a radial nozzle attached to the ellipsoidal head. In order to get better understanding of the structure behavior, a parametric study was carried out to determine influences of the geometrical parameters. All the results analysis was presented as graphs of non-dimensional parameters against stress concentration factor (SCF) for each load case applied.

Abstract: Ceramic/metal bimaterials systems are increasingly used in industry owing to the synergetic association of opposite properties of the bonded materials. Discontinuity in these properties can result in crack initiation and stress concentration entailing the bimaterial system failure. A good understanding of damage mechanism at the metal/ceramic interface is crucial to the dimensioning of multilayered systems. In this work the finite element method is used to analyze the stress concentration effect in a linear interface and curved interface. The geometrical configuration of the interface has a great influence the stress concentration on distribution developed near or in the assembly interface. The effect of a circular notch on the behavior of an interfacial crack is highlighted. The results indicate that the interface generates normal and tangential stress concentration resondless of the assembly mechanical properties. The curved geometry of the interface strongly reduces stress concentration in comparison with the linear interface. The reduction is 90%.

Abstract: The tip radius ρ, depth t and field angle α of notch and the geometrical sizes a and b of shaft are looked as descriptive parameters in the annular notched shaft. Taken the crack, blunt crack and notch as breach, the stress field and displacement field near the tip of breach which serve dimensionless factor f_α(a/b) as descriptive parameter are obtained. The effects of parameters ρ, t and α to f_α(a/b) are analyzed. The connections between stress intensity factor of crack and stress concentrator factor of notch, between sharp V-notch and crack, between V-notch and U-notch have been founded.

Abstract: This paper reports on experimental test and numerical simulation methods that investigate the stress concentration factor and node deformation performance parameters for tubular KK-joints. The numerical analysis can give reference for design schemes of model test, and the bearing characteristics are studied by the model test. Moreover, by comparing the experimental analysis and the finite element simulation results, we discuss the accuracy of numerical analysis method in analyzing the tubular joints stress concentration factor. These can provide a useful reference for the engineering design.

Abstract: By research of simple tubular joints, thin-shell element analyses have been conducted for thousands of DTK joints frequently used in offshore structures in this paper. These joints are subjected to axial load, by use of nonlinear least squares fitter, the above results are derived a new set of parametric equations, in terms of several non-dimensional geometric ratios γ, ξ, β, τ and θ with the Origin software. Separate analyses have been conducted for the difference of SCFs in DTK joints and SCFs for TK joint from empirical formulas. The SCF results of these joints could act as a good reference for both further academic studies on SCF of other complex joints and engineering designing works.

Abstract: In the case of large diameter polyethylene (PE) and polypropylene (PP) pipes the most usual joint is the butt weld. This paper focuses on the influence of a weld bead on the service life of welded pipes from a fracture mechanics perspective. To this aim the stress concentrator created by the connection between the weld bead and the pipe’s free surface is modelled as a notch. Global parameters defining properties of stress and strain field in the notch region are calculated for materials with a prevailing Norton-type creep. It is demonstrated that in the case of creep loading conditions and ductile failure mode the existence of such stress concentrators has no negative influence on the lifetime of pipes.

Abstract: The elastic stress and strain fields of a finite-thickness plate containing two interacting holes are systematically investigated using the finite element method. The maximum stress and strain concentrations occur on the mid plane only in the thin plates. They do not occur on the mid plane and their locations are different in the same plate for the thick plates. The values of the maximum stress and the strain concentration factor and their locations depend on the distance between the two holes and the plate thickness. The stress and the strain concentration factor are different, even if in an elastic state. The stress concentration factor and the strain concentration factor on the plate surface decrease rapidly with increasing thickness and becomes lower than the values corresponding to the plane stress state and the values of the mid plane. They are too low to reflect the overall stress concentrations as the plate thickness increases. The differences between the maximum value and the surface value of the stress concentration factor, the strain concentration factor increase rapidly and tend to their respective constant values with increasing plate thickness. These constant values depend on the distance between the two holes and the difference of the stress concentration factor is larger than that of the strain concentration factor in the same plate.

Abstract: The object of this study is to find out and evaluate systematically how the basic factors such as graphite-shape, external notch and matrix-characteristic affect the impact and bending characteristics of cast irons. The Spheroidal Graphite (SG) and Compacted Vermicular graphite (CV) cast iron samples were prepared, and their matrixes were modified into ferritic, pearlitic and bainitic in order to make the various kinds of samples whose graphite-shape and matrix vary widely. From each sample we produced five kinds of Charpy-type specimens by adding five kinds of notches whose stress concentration factor (α) varied from 1.0 (un-notched) to 4.8. The Charpy impact value decreases greatly in the range of α from 1 to 2.3 but decreases slightly in the range of α larger than 2.3. No influence to the fracture energy in the range of α larger than 2.3. Increasing of α results in moderate elevation of transition temperature of Charpy impact value and the transition temperature of CV cast ion is lower than that of SG one. The impact value in brittle fracture region of the cast iron samples were recognized to be a little bit larger than that of cast steel sample, and it was considered to be caused by graphite which act as a kind of buffer effect against crack growth in brittle fracture.

Abstract: By terms of the numerical modeling of ABAQUS software, the analysis of the stress concentration factor (SCF) of tubular T-joints subjected to axial load is analyzed in this paper. The magnitude and the distribution of the SCF are also obtained. Through the finite element analysis of 816 models, the effect of geometrical parameters on the value and distribution of the SCF is investigated. Then based on these results, the parametric equations of the maximal SCF and SCF distribution for T-joints subjected to axial load are presented. Error analysis of these parametric equations is also carried out.

Abstract: The elastic stress and strain fields in a circular cross-section bar with semielliptic groove subjected to uniaxial tension are systematically investigated using the finite element method. It is found that the stress and strain concentrations are different even if the material is in the elastic state. The relation between the stress and the strain concentration factors depends on Poisson’s ratio and the groove’s geometric configuration. The coupled influences of the shape factor of the semielliptic groove and the relative depth of the groove on the stress and strain concentrations are examined. The equations that describe the stress and strain concentration factors for different groove’s geometric configurations and Poisson’s ratios are obtained based on finite element results.