Isogeometric Analysis Prediction of Stress Concentration Factor of Trivariate NURBS-Based Rectangular Plate with Central Elliptical Hole

2014 ◽  
Vol 556-562 ◽  
pp. 742-746
Author(s):  
Yusuf Olatunbosun Tafa ◽  
Gang Zhao ◽  
Wei Wang
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Isogeometric Analysis ◽  
Concentration Factor ◽  
Three Dimensional ◽  
Elliptical Hole ◽  
The Body ◽  
Geometric Discontinuities ◽  
Trivariate Nurbs ◽  
Good Agreement

Experimental, analytical and finite element techniques are commonly known methods used in determining highly localized stress occurring in the body under loading as a result of geometric discontinuities. In this study, we use NURBS-based isogeometric analysis (IGA) to investigate the stress concentration factor (SCF) on three-dimensional geometry with discontinuity feature. The results show that IGA technique is in good agreement with analytical values, thus providing a more effective realistic way of determining SCF.

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.

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.

scholarly journals Stress Concentration and Damage Factor Due to Central Elliptical Hole in Functionally Graded Panels Subjected to Uniform Tensile Traction

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 422 ◽  
Author(s):  
Wenshuai Wang ◽  
Hongting Yuan ◽  
Xing Li ◽  
Pengpeng Shi
Keyword(s):  
Stress Concentration ◽  
Optimal Design ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Elliptical Hole ◽  
Tensile Load ◽  
Functionally Graded ◽  
Uniaxial Tensile ◽  
Damage Factor ◽  
Failure Index

Functionally graded material (FGM) can optimize the mechanical properties of composites by designing the spatial variation of material properties. In this paper, the stress distribution of functionally graded panel with a central elliptical hole under uniaxial tensile load is analyzed. Based on the inhomogeneity variation and three different gradient directions, the effects of the inhomogeneity on the stress concentration factor and damage factor are discussed. The study results show that when Young’s modulus increases with the distance from the hole, the stress concentration factor decreases compared with that of homogeneous material, and the optimal design of r-FGM is better than that of x-FGM and y-FGM when the tensile load. In addition, when the associated variation of ultimate stress is considered, the choice of scheme to reduce the failure index is related to the strength-modulus exponent ratio. When the strength-modulus exponent ratio is small, the failure index changes with the index of power-law, which means there is an optimal FGM design. But when the strength-modulus exponent ratio is large, the optimal design modulus design is to select a uniform material that maximizes the modulus at each point. These research results have a certain reference value for further in-depth understanding of the inhomogeneous design for FGM.

A numerical approach to determine fiber orientations around geometric discontinuities in designing against failure of GFRP laminates

2019 ◽  
Vol 10 (3) ◽  
pp. 371-379 ◽  
Author(s):  
Roselita Fragoudakis
Keyword(s):  
Stress Concentration ◽  
Plastic Zone ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Load Condition ◽  
Content Type ◽  
Geometric Discontinuities ◽  
Failure Theories ◽  
Laminated Structures ◽  
Minimum Moment

Purpose Determining fiber orientations around geometric discontinuities is challenging and simultaneously crucial when designing laminates against failure. The purpose of this paper is to present an approach for selecting the fiber orientations in the vicinity of a geometric discontinuity; more specifically round holes with edge cracks. Maximum stresses in the discontinuity region are calculated using Classical Lamination Theory (CLT) and the stress concentration factor for the aforementioned condition. The minimum moment to cause failure in a lamina is estimated using the Tsai–Hill and Tsai–Wu failure theories for a symmetric general stacking laminate. Fiber orientations around the discontinuity are obtained using the Tsai–Hill failure theory. Design/methodology/approach The current research focuses on a general stacking sequence laminate under three-point bending conditions. The laminate material is S2 fiber glass/epoxy. The concepts of mode I stress intensity factor and plastic zone radius are applied to decide the radius of the plastic zone, and stress concentration factor that multiplies the CLT stress distribution in the vicinity of the discontinuity. The magnitude of the minimum moment to cause failure in each ply is then estimated using the Tsai–Hill and Tsai–Wu failure theories, under the aforementioned stress concentration. Findings The findings of the study are as follows: it confirms the conclusions of previous research that the size and shape of the discontinuity have a significant effect on determining such orientations; the dimensions of the laminate and laminae not only affect the CLT results, but also the effect of the discontinuity in these results; and each lamina depending on its position in the laminate will have a different minimum load to cause failure and consequently, a different fiber orientation around the geometric discontinuity. Originality/value This paper discusses an important topic for the manufacturing and design against failure of Glass Fiber Reinforced Plastic (GFRP) laminated structures. The topic of introducing geometric discontinuities in unidirectional GFRP laminates is still a challenging one. This paper addresses these issues under 3pt bending conditions, a load condition rarely approached in literature. Therefore, it presents a fairly simple approach to strengthen geometric discontinuity regions without discontinuing fibers.

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.

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.

Engineering Procedure for Calculation of Elastic Stress Concentration Factors of Bearing Pad Fretting Flaws

2009 ◽  
Author(s):  
Bogdan S. Wasiluk ◽  
Douglas A. Scarth
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Crack Initiation ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Elastic Stress ◽  
Elliptical Hole ◽  
Flat Bottom ◽  
Concentration Factors ◽  
Stress Concentration Factors

Procedures to evaluate volumetric bearing pad fretting flaws for crack initiation are in the Canadian Standard N285.8 for in-service evaluation of CANDU® pressure tubes. The crack initiation evaluation procedures use equations for calculating the elastic stress concentration factors. Newly developed engineering procedure for calculation of the elastic stress concentration factor for bearing pad fretting flaws is presented. The procedure is based on adapting a theoretical equation for the elastic stress concentration factor for an elliptical hole to the geometry of a bearing pad fretting flaw, and fitting the equation to the results from elastic finite element stress analyses. Non-dimensional flaw parameters a/w, a/c and a/ρ were used to characterize the elastic stress concentration factor, where w is wall thickness of a pressure tube, a is depth, c is half axial length, and ρ is root radius of the bearing pad fretting flaw. The engineering equations for 3-D round and flat bottom bearing pad fretting flaws were examined by calculation of the elastic stress concentration factor for each case in the matrix of source finite element cases. For the round bottom bearing pad fretting flaw, the fitted equation for the elastic stress concentration factor agrees with the finite element results within ±3.7% over the valid range of flaw geometries. For the flat bottom bearing pad fretting flaw, the fitted equation agrees with the finite element results within ±4.0% over the valid range of flaw geometries. The equations for the elastic stress concentration factor have been verified over the valid range of flaw geometries to ensure accurate results with no anomalous behavior. This included comparison against results from independent finite element calculations.

Theoretical and Experimental Study of the Stress Concentration Factor in Diesel Engine Crankshafts

1993 ◽  
Vol 115 (1) ◽  
pp. 47-52 ◽  
Author(s):  
M. Guagliano ◽  
A. Terranova ◽  
L. Vergani
Keyword(s):  
Diesel Engine ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Complex Geometry ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Considerable Saving ◽  
Three Dimensional Finite Element ◽  
Load Conditions

The paper deals with the bending stress concentration evaluation of a marine diesel engine crankshaft. Experimental strain gauge tests were conducted on a full scale single crank to measure the stress concentration near the crank fillet. A three-dimensional finite element schematization of the crankshaft and the linear elastic calculations conducted show the stress field along the most overstressed zone and how it is influenced by different load conditions. It is now possible to calculate accurately the stress concentration factor Kt. However, a mesh of a mechanical element with a complex geometry like crankshaft is very expensive and difficult. Therefore a bidimensional model of the crankshaft has been also considered: experimental tests and numerical analyses under different load conditions were also carried out in this case. The agreement between the results obtained from these different kinds of analyses is good. The values of the stress concentration factors obtained from bidimensional and three-dimensional analysis with the same boundary and load conditions are similar. A plane model of crankshaft can be utilized to determine the theoretical stress concentration factor Kt with considerable saving of calculation time.

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