Three-Dimensional Elastic Stress Fields of Finite Thickness Plates with Elliptical Hole

2007 ◽  
Vol 353-358 ◽  
pp. 74-77
Author(s):  
Zheng Yang ◽  
Chong Du Cho ◽  
Ting Ya Su ◽  
Chang Boo Kim ◽  
Hyeon Gyu Beom
Keyword(s):  
Stress Concentration ◽  
Plane Strain ◽  
Plane Stress ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Maximum Stress ◽  
Elastic Stress ◽  
Finite Thickness ◽  
Plate Thickness ◽  
Three Dimensional

Based on detailed three-dimensional finite element analyses, elastic stress and strain field of ellipse major axis end in plates with different thickness and ellipse configurations subjected to uniaxial tension have been investigated. The plate thickness and ellipse configuration have obvious effects on the stress concentration factor, which is higher in finite thickness plates than in plane stress and plane strain cases. The out-of-plane stress constraint factor tends the maximum on the mid-plane and approaches to zero on the free plane. Stress concentration factors distribute ununiformly through the plate thickness, the value and location of maximum stress concentration factor depend on the plate thickness and the ellipse configurations. Both stress concentration factor in the middle plane and the maximum stress concentration factor are greater than that under plane stress or plane strain states, so it is unsafe to suppose a tensioned plate with finite thickness as one undergone plane stress or plane strain. For the sharper notch, the influence of three-dimensional stress state on the SCF must be considered.

The Stress and Strain Concentrations Associated with Two Interacting Holes in a Finite Thickness Elastic Plate Subjected to Tensile Stress

2011 ◽  
Vol 462-463 ◽  
pp. 48-53 ◽  
Author(s):  
Zheng Yang ◽  
Jian Hou ◽  
Guo Yin Wang ◽  
Zhi Hua Xiong
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Maximum Stress ◽  
Finite Thickness ◽  
Plate Thickness ◽  
Thin Plates ◽  
Stress And Strain ◽  
Stress Concentrations ◽  
Strain Concentration

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.

Elastic Stress Concentration Factors (Kt) by Stress Gradient Method Using FEA

1996 ◽  
Author(s):  
Ajay Garg ◽  
Ravi Tetambe
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Maximum Stress ◽  
Elastic Stress ◽  
Stress Gradient ◽  
Nominal Stress ◽  
Element Analysis

Abstract The elastic stress concentration factor, Kt, is critical in determining the life of machines, especially in the case of notched components experiencing high cycle fatigue. This Kt is defined as the ratio of the maximum stress (σmax) at the notch to the nominal stress (σnom) in the region away from the notch effect. For simple geometries such as, plate with a hole, calculation of Kt from either closed form solution or from making simple but valid assumptions is possible [1,2]. However, for complex machine components such data is usually not available in the literature. Using Kt values from the simple geometries may lead to either over or under estimation of the real Kt for such complex geometries. Such error can then further lead to a substandard product or a product which is overdesigned and expensive. Present paper outlines a methodology for computing reasonably accurate elastic stress concentration factor, Kt, using finite element analysis (FEA) tool. The maximum stress (σmax) is readily available from the finite element analysis. The nominal stress (σnom) near the stress concentration is however can not be directly extracted from the FEA results. A novel approach of estimating reasonably accurate σnom is presented in this paper. This approach is based on selecting the correct path at the stress concentration region, post processing the stress and the stress gradient results along that path and identifying the cut of point where stress concentration effect begins to take place. This methodology is first validated using two examples with known Kt and later applied to a real world problem.

Stress-Concentration Factors for a Countersunk Hole in a Flat Bar in Tension and Transverse Bending

1978 ◽  
Vol 45 (4) ◽  
pp. 929-932 ◽  
Author(s):  
Y. F. Cheng
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Maximum Stress ◽  
Three Dimensional ◽  
Neutral Plane ◽  
Transverse Bending ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Maximum Stresses

A series of three-dimensional photoelastic experiments was performed to determine the maximum stresses and stress-concentration factors at countersunk holes in a flat bar in tension and transverse bending. In the tension case, the maximum stress was found at the base of the countersunk and the stress-concentration factor was approximately 33 percent higher than those found in a straight hole. In the bending case, the neutral plane was shifted toward the surface containing the straight part of the hole and the stress-concentration factor was practically the same as those found in straight holes.

Simple formulae for the stress concentration factor for two- and three-dimensional holes in finite domains

2002 ◽  
Vol 37 (3) ◽  
pp. 259-264 ◽  
Author(s):  
Q. Z Wang
Keyword(s):  
Stress Concentration ◽  
Circular Hole ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Spherical Cavity ◽  
Three Dimensional ◽  
Finite Domain ◽  
Three Dimensional Models ◽  
Finite Domains ◽  
Asymptotic Validity

First, based on an approximate analysis, simple closed-form expressions of the stress concentration factor (SCF) for two- or three-dimensional models with a circular hole or a spherical cavity in a finite domain are derived. Then, an asymptotic method is adopted to improve the accuracy of the derived solutions for an extremely large circular hole or spherical cavity, when the remaining ligament approaches zero. Exact limit SCF values for these two kinds of models were given by Koiter; these values are used for the adjustment of the coefficients in the SCF expressions. Finally, simple SCF formulae for these finite domain problems are obtained, their accuracy is demonstrated to be very good by comparison with the available data from the literature, and the asymptotic validity is guaranteed.

scholarly journals Stress concentration and optimal design of pinned connections

2019 ◽  
Vol 54 (2) ◽  
pp. 95-104 ◽  
Author(s):  
Niels Leergaard Pedersen
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Mechanical Engineering ◽  
Maximum Stress ◽  
Civil Engineering ◽  
Three Dimension ◽  
Element Analysis ◽  
Standard Design ◽  
Connection Type

A pinned connection or lug joint is a common connection type used both in civil engineering and mechanical engineering. In civil engineering, this connection is used for assembling truss members, and in mechanical engineering, this connection type is widely used in machine elements. The standard design is with a circular pin. The stress concentration factor size depends on the tolerances between pin and assembled parts and also by the three-dimensional design. Relatively different maximum stress values are seen depending on the modelling being done in two dimension (with assumptions) or in full three dimension. The focus in the present article is on the two-dimensional design and minimizing the maximum stress. It is shown that not only the contact geometry is important for reducing the stress, the external design is equally important. By finite element analysis including contact modelling, it is shown that reduction in the stress concentration factor of up to 18% is possible.

Numerical Investigation of Stress Concentration Factor at Irregular Corrosion Pit Under Tension-Torsion Loading

2014 ◽  
Author(s):  
Yuhui Huang ◽  
Chengcheng Wang ◽  
Shan-Tung Tu ◽  
Fu-Zhen Xuan ◽  
Takamoto Itoh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Aspect Ratio ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Three Dimensional ◽  
Element Analysis ◽  
Stress Concentration Factors ◽  
Local Dissolution

Finite element analysis is adopted to study the stress concentration of pit area under tension-torsion loading. The stress concentration factors under regular evolution and irregular evolution of pits are investigated by conducting a series of three-dimensional semi-elliptical pitted models. Based on the finite element analysis, it can be concluded that pit aspect ratio (a/2c) is a significant parameter affecting stress concentration factor (SCF) for regular evolution pits. Pits, having higher aspect ratio, are very dangerous form and can cause significant reduction in the load carrying capacity. When local dissolution occurs in the pitting area, SCF will have a sharp increase, it is more probable for a crack to initiate from these areas compared with pits for regular evolution. Furthermore, local dissolution coefficient is proposed to study effect of local dissolution within the pit on SCF.

Stress Analysis of O.D. Notched Thick-Walled Cylinders Subjected to Internal Pressure or Thermal Loads

1981 ◽  
Vol 103 (1) ◽  
pp. 76-84 ◽  
Author(s):  
J. A. Kapp ◽  
G. A. Pflegl
Keyword(s):  
Stress Concentration ◽  
Residual Stresses ◽  
Internal Pressure ◽  
Stress Analysis ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Maximum Stress ◽  
Additional Result ◽  
Finite Element Stress Analysis ◽  
Temperature Loads

Finite element stress analysis has been performed to determine the effects of two O.D. notch configurations in a cylinder subjected to internal pressure, or containing autofrettage residual stress. The effects on the residual stresses were determined by simulating these stresses with equivilent temperature loads. The results show that the deeper of the two notch cofigurations is far more severe resulting in a maximum stress concentration factor of 6.6. The shallower notch has a maximum stress concentration factor of 3.7. An additional result is that by introducing notches in autofrettaged cylinders a significant amount of the residual stresses are relieved which indicates that smaller applied pressures can be applied before yielding occurs. The results also show that the possibility of O.D. initiated fatigue failure is greatly increased.

Effects of Perforation on the Collapsing Strength of Casing

2013 ◽  
Vol 395-396 ◽  
pp. 881-886
Author(s):  
Yu Guang Cao ◽  
Shi Hua Zhang ◽  
Xin Ren
Keyword(s):  
Stress Concentration ◽  
Flat Plate ◽  
Elasticity Theory ◽  
Stress Concentration Factor ◽  
Mechanical Model ◽  
Concentration Factor ◽  
Three Dimensional ◽  
Theoretical Equation ◽  
Fem Model ◽  
Strength Factor

In this study, three-dimensional mechanical model of the perforated casing was simplified as flat plate mechanical model. The theoretical equation for the calculation of collapsing strength factor for a perforated casing under squeeze was derived as per elasticity theory. Three-dimensional FEM model of a perforated casing was built using ANSYS and analysis was performed. The stress concentration factor (SCF) was discussed for perforated casing in this paper and the effects of aperture on SCFs were analyzed in detail.

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