Optimization of Defense Hole System for Biaxial Loaded Plate with Three Coaxial Holes

2005 ◽  
Vol 8 (2) ◽  
pp. 117-128 ◽  
Author(s):  
Montasser Tahat ◽  
Salih Akour ◽  
Saad Habali ◽  
Jamal Nayfeh
Keyword(s):  
Stress Reduction ◽  
Maximum Stress ◽  
Biaxial Loading ◽  
Hole Diameter ◽  
Optimum Shape ◽  
Element Analysis ◽  
Principal Stress Direction ◽  
Structural Part ◽  
The Finite Element Analysis ◽  
Circular Holes

Optimum design of elliptical Defense Hole System (DHS) under biaxial loading in a finite plate with a row of circular holes is presented. Maximum stress reduction is made possible by introducing elliptical auxiliary holes close to the mainmain holes in the areas of low stresses along the principal stress direction. A systematic study is undertaken by using the finite element analysis (FEA) to determine the optimum shape, location and size of the auxiliary defense hole system. These parameters are examined in relation to plate dimensions for a number of plates with different mainmain-hole-diameter to plate-width ratios and different pitch to main-hole-diameter ratios. Maximum stress reductions from 6–18% were achieved. With such reduction in the maximum stress level the improvement in fatigue life of a structural part can be very significant. The FEA results are validated experimentally by applying an enhanced RGB-photoelasticity technique. The photoelasticity experimental results and the FEA results show good agreement.

DEFENSE HOLE DESIGN FOR A SHEAR DOMINANT LOADED PLATE

2010 ◽  
Vol 02 (02) ◽  
pp. 381-398 ◽  
Author(s):  
SALIH N. AKOUR ◽  
JAMAL F. NAYFEH ◽  
DAVID W. NICHOLSON
Keyword(s):  
Stress Reduction ◽  
Maximum Stress ◽  
Principal Direction ◽  
Crack Arrest ◽  
Optimization Techniques ◽  
Baseline Data ◽  
Load Range ◽  
Element Analysis ◽  
Structural Part ◽  
Circular Holes

Baseline data is produced for designing an optimum Defense Hole System (DHS) for a large plate with a circular hole in shear dominant-load range. Stress concentration associated with circular holes for tensile/shear ratio ranging from 0% to 25% is reduced by 13.5% to 16.67%, respectively. This reduction is achieved by introducing auxiliary elliptical holes (i.e., DHS) along the principal stress directions. Each pair lies along the same principal direction has the same geometry and placement on either side of the main hole. These holes are placed in the low stress regions. With such reduction in the maximum stress level, the improvement in fatigue life of a structural part can be very significant. Both redesign optimization and parametric optimization techniques are utilized to reach the optimum solutions and to generate the baseline data. Finite Element Analysis (FEA) is used to evaluate the stresses and to optimize the size and location of the DHS. The optimum cases are validated using the RGB-photoelasticity technique. Three main goals are achieved by introducing such holes: maximum stress reduction, working as crack arrest in case a crack propagates, and material reduction.

DEFENSE HOLE DESIGN FOR UNIAXIAL DOMINANT HYBRID LOAD FOR INFINITE PLATE

2011 ◽  
Vol 03 (03) ◽  
pp. 607-623 ◽  
Author(s):  
S. N. AKOUR ◽  
J. F. NAYFEH
Keyword(s):  
Stress Reduction ◽  
Stress Ratio ◽  
Maximum Stress ◽  
Optimization Technique ◽  
Infinite Plate ◽  
Optimization Method ◽  
Tensile Shear ◽  
Element Analysis ◽  
Principal Stress Direction ◽  
Circular Holes

A baseline data for designing optimum Defense Hole System (DHS) for tension dominant hybrid load (Tensile/Shear > 25%) is obtained. Maximum stress reduction and optimum DHS parameters are achieved. The maximum stress reduction achieved range from 15% up to nearly 18% based on the principle stress ratio (25% < Tensile/Shear < 100%). This reduction is available by introducing auxiliary circular holes, i.e., DHS, along the principal stress direction. A two-DHS is shown to be the optimum for tensile dominant loaded plate. Two major goals are achieved by introducing such defense system: maximum stress reduction and material reduction. Redesign optimization method (iterative numerical optimization technique) is utilized to investigate this problem. Parametric optimization technique is also utilized in producing the routs for reaching those optimum cases. Finite element analysis is used to optimize the size and the location of the DHS. Selected optimum cases are verified experimentally using RGB photoelasticity.

scholarly journals Reinforcement Effect of a Concrete Mat to Prevent Ground Collapses Due to Buried Pipe Damage

2020 ◽  
Vol 10 (16) ◽  
pp. 5439
Author(s):  
Jeongjun Park ◽  
Yoonseok Chung ◽  
Gigwon Hong
Keyword(s):  
Stress Reduction ◽  
Maximum Stress ◽  
Ground Subsidence ◽  
Reinforcement Effect ◽  
Uniform Load ◽  
Buried Pipe ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Installation Depth ◽  
Load Conditions

This study described a ground reinforcement effect of a concrete mat, in order to apply a concrete mat for ground subsidence restoration of an open cut. A concrete mat can prevent the expansion of a cavity and relaxation area underground due to buried pipe damage when the buried pipe is in use. An experimental study was conducted to analyze the stress distribution characteristics of an underground area by ground reinforcement of a concrete mat. In addition, a numerical analysis was performed to estimate the range of underground reinforcement of a concrete mat. As an experiment results, the maximum stress reduction ratio of the concrete mat in the underground was 28.5% to 30.9%, which means the reinforcement effect of the concrete mat, according to the installation depth of the concrete mat. The finite element analysis (FEA) results showed that the installation depth of the concrete mat differed in various scenarios, in order to secure the reinforcement effect of the concrete mat according to the load conditions (point and uniform load). Therefore, the reinforced depth of a concrete mat should be determined by the load type on the surface.

Determination of Stress Concentration Around an Oblique Hole by a Finite-Element Technique

1983 ◽  
Vol 105 (2) ◽  
pp. 206-212 ◽  
Author(s):  
Hua-Ping Li ◽  
F. Ellyin
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Maximum Stress ◽  
Plate Thickness ◽  
Two Dimensional ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Parametric Studies ◽  
Element Technique

A plate weakened by an oblique penetration of a circular cylindrical hole has been investigated. The stress concentration around the hole is determined by a finite-element method. The results are compared with experimental data and other analytical works. Parametric studies of effects of angle of inclination, plate thickness, and width are performed. The maximum stress concentration factor (SCF) obtained from the finite-element analysis is higher than experimental results, and this deviation increases with the increase of angle of skewness. The major reason for this difference is attributed to the shear-action between layers parallel to the plate surface which cannot be directly included in the two-dimensional elements. An empirical formula is derived which accounts for the shear-action and renders the finite-element predictions in line with experimentally observed data.

scholarly journals Modeling of Size Effects in Bending of Perforated Cosserat Plates

2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Roman Kvasov ◽  
Lev Steinberg
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Numerical Study ◽  
The Finite Element Method ◽  
Classical Elasticity ◽  
Element Analysis ◽  
Plate Deformation ◽  
The Finite Element Analysis ◽  
Circular Holes ◽  
Different Shapes

This paper presents the numerical study of Cosserat elastic plate deformation based on the parametric theory of Cosserat plates, recently developed by the authors. The numerical results are obtained using the Finite Element Method used to solve the parametric system of 9 kinematic equations. We discuss the existence and uniqueness of the weak solution and the convergence of the proposed FEM. The Finite Element analysis of clamped Cosserat plates of different shapes under different loads is provided. We present the numerical validation of the proposed FEM by estimating the order of convergence, when comparing the main kinematic variables with an analytical solution. We also consider the numerical analysis of plates with circular holes. We show that the stress concentration factor around the hole is less than the classical value, and smaller holes exhibit less stress concentration as would be expected on the basis of the classical elasticity.

Failure Criteria for Brittle Notched Specimens

2022 ◽  
Author(s):  
Young W. Kwon ◽  
Carlos Diaz-Colon ◽  
Stanley Defisher
Keyword(s):  
Elliptical Hole ◽  
Failure Criteria ◽  
Homogeneous Material ◽  
Carbon Fiber Composites ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Theoretical Predictions ◽  
Circular Holes ◽  
Failure Loads ◽  
Stress Models

Abstract Recently, new failure criteria were proposed for brittle materials to predict their failure loads regardless of the shapes of a notch or a crack in the material. This paper is to further evaluate the failure criteria for different shapes of notches and different materials. A circular hole, elliptical hole or crack-like slit with a different angle with respect to the loading direction was considered. Double circular holes were also studied. The materials studied were an isotropic material like polymethyl methacrylate (PMMA) as well as laminated carbon fiber composites. Both cross-ply and quasi-isotropic layup orientations were examined. The lamination theory was used for the composite materials so that they can be modelled as an anisotropic and homogeneous material. The test results were compared to the theoretical predictions using the finite element analysis with 2-D plane stress models. Both theoretical failure stresses agreed well with the experimental data for the materials and notch geometries studied herein.

scholarly journals The Effect of Knee Flexion Angle on Contact Stress of Total Knee Arthroplasty

2018 ◽  
Vol 225 ◽  
pp. 03009 ◽  
Author(s):  
N.M.A. Azam ◽  
Rosdi Daud ◽  
H. Mas Ayu ◽  
J. Ramli ◽  
M.F.B. Hassan ◽  
...  
Keyword(s):  
Finite Element ◽  
Total Knee Arthroplasty ◽  
Contact Stress ◽  
Knee Arthroplasty ◽  
Maximum Stress ◽  
Flexion Angle ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Current Design ◽  
Total Knee

The effect of flexion angle on contact stress of the knee joint still open to the debate since lack of proof shown that flexion angles does effect the contact stress of Total Knee Arthroplasty (TKA). Thus the aim of this study is to investigate the effect of different flexion angle on contact stress of TKA via finite element method. The TKA is simulated using ANSYS Workbench and the applied loads are 2200 N, 3200 N and 2800 N. The Finite element Analysis (FEA) results for maximum stress of current and proposed designed were then compared. For the new proposed design, the maximum stress for 15° is 12.2 MPa, 45° is 23.6 MPa and 60° is 22.5 MPa which is lower than current design. Thus, it can be concluded that the new proposed design better than current design in term of contact stress. While, the different flexion angle do gives an impact on the performance of the TKA.

The Analysis of Mutual Authentication between Finite Element Analysis and Qi Erxi Answer

2011 ◽  
Vol 396-398 ◽  
pp. 1228-1231
Author(s):  
Yu Li Liu ◽  
Hai Bo Liu ◽  
Bo Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Maximum Stress ◽  
Mutual Authentication ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Edge Stress

In this paper, the sheet with hole for the finite element analysis, the location of maximum stress and maximum stress values are obtained under different load of edge of the hole, and the finite element analysis results compared with the classic Qi Erxi answers. This coincidence is not accidental, but it just shows their correctness. Therefore, we can use Qi Erxi answer when the calculation of the hole’s edge stress concentration and the condition of the force and the boundary are simple; while the it is complex, the finite element analysis can be used.

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