Blending Hierarchical Economic Decision Matrices (EDM) With FE and Stochastic Modeling: II — Detailing EDM

1996 ◽  
Author(s):  
J. N. Majerus ◽  
D. A. Tenney ◽  
M. L. Mimnagh ◽  
S. P. Lamphear ◽  
J. A. Jannone
Keyword(s):  
Boundary Conditions ◽  
Fatigue Fracture ◽  
Stochastic Modeling ◽  
Three Dimensional ◽  
Fe Analysis ◽  
Material Strength ◽  
Complete Reversal ◽  
D Model ◽  
Fine Tune ◽  
Maximum Stresses

Abstract The purpose of the Detailing EDM is to “fine-tune” a previously ameliorated design. First, in order to determine the best fillet radius for formability, forging simulations are conducted using commercial software. Once the fillet dimension is ascertained, the 3-D model is generated and maximum stresses determined for a trial force. Two different commercial programs were used to determine the three dimensional stresses. The only statistical quantities involve the loading (Gaussian distribution), the material “strength” in the Analytical Criteria for Failure (ACF), and possibly, the boundary conditions in the 3-D models. This paper considers the ACF to be the resistance to fatigue-fracture under complete reversal of loads at 5 × 108 cycles. The paper overviews three different methods of combining stochastic behaviour with FE analysis, and presents a methodology for using the interference-method with non-symmetrical distributions. The EDM are then presented for the three Product Criteria of forging — formability, Prime cost and 3-D reliability with respect to the selected ACF.

Three-dimensional numerical modelling of the drained/undrained transition for frequency-dependent elastic moduli and attenuation

2019 ◽  
Vol 219 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Chao Sun ◽  
Genyang Tang ◽  
Jianguo Zhao ◽  
Liming Zhao ◽  
Teng Long ◽  
...  
Keyword(s):  
Numerical Model ◽  
Boundary Conditions ◽  
Elastic Moduli ◽  
Forced Oscillation ◽  
Three Dimensional ◽  
Frequency Dependent ◽  
Measurement Results ◽  
D Model ◽  
Dispersion And Attenuation ◽  
Oscillation Method

SUMMARY In fully fluid-saturated rocks, two common phenomena are documented both experimentally and theoretically for frequency-dependent elastic moduli and attenuation, that is, the drained/undrained transition and the relaxed/unrelaxed transition. When investigating these transitions with the forced oscillation method in the laboratory, it is crucial to consider the boundary differences between the laboratory and the underground. A 1-D poroelastic numerical model was previously established to describe these differences and their effects; however, the boundary conditions used in the model are actually different from the real experiment case, thus leading to inaccurate predication of the measurement results in a laboratory. In this paper, we established a 3-D poroelastic numerical model with a new set of boundary conditions that better represent the experiment conditions. Furthermore, the 3-D poroelastic modelling results were compared with laboratory measurements under the same boundary conditions, showing a much better fit than the 1-D model. Therefore, the 3-D model provides a more accurate and reliable approach to understand the regimes and transitions of elastic modulus dispersion and attenuation, and thus has great importance in interpreting the measurements of frequency-dependent properties of rocks in the laboratory.

Evaluation of Applicability of Ultrathin Whitetopping in Florida

2003 ◽  
Vol 1823 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Wasantha Kumara ◽  
Mang Tia ◽  
Chung-Lung Wu ◽  
Bouzid Choubane
Keyword(s):  
Applied Load ◽  
Three Dimensional ◽  
Poor Performance ◽  
Element Model ◽  
Loading Conditions ◽  
Temperature Differential ◽  
Critical Loading ◽  
Satisfactory Performance ◽  
D Model ◽  
Maximum Stresses

A three-dimensional (3-D) finite element model for stress analysis of pavements with ultrathin whitetopping (UTW) under critical loading conditions was developed. The 3-D model developed was used to analyze the UTW test pavement sections at the Ellaville Weigh Station in Florida, which had less than satisfactory performance. The poorly performing UTW sections at the Ellaville Weigh Station were found to have relatively higher maximum computed stresses under critical loading conditions, which appeared to explain their poor performance and high percentages of cracked slabs. The 3-D model developed was also used to perform a parametric analysis to determine the effects of asphalt thickness, asphalt modulus, concrete thickness, concrete modulus, base stiffness, subgrade stiffness, slab dimension, temperature differential in the concrete, and applied load on the maximum stresses in UTW pavements under typical Florida conditions.

Stress of a Rocket Turbine under Different Loads Using Finite Element Modeling

2012 ◽  
Vol 232 ◽  
pp. 691-696
Author(s):  
Elhefny Amr ◽  
Guo Zhu Liang
Keyword(s):  
Finite Element ◽  
Rocket Engine ◽  
Three Dimensional ◽  
Fe Analysis ◽  
Liquid Rocket Engine ◽  
Operating Speed ◽  
Thermal Loads ◽  
Liquid Rocket ◽  
Maximum Stresses ◽  
Selection Of

Turbopump unit is a key component of the liquid rocket engine assembly and in this paper stresses of a turbopump turbine are investigated using finite element (FE) analysis. Three-dimensional solid modeling of a group of blades and a sector of the disc was first created on CAD software and subsequently exported to a FE package for analysis. The FE results reveals that the maximum stresses in the blades result from rotational and thermal loads owing to the relatively high operating speed and temperature of the turbine and they are located at the root of the blades. Also, the maximum stresses in the disc result from rotational and thermal loads, but with higher values than those in the blades and they are located at the center of the disc. The result of this study may serve as a guideline in the selection of the materials for both the disc and blades.

Pavement Damage Due to Conventional and New Generation of Wide-Base Super Single Tires

2005 ◽  
Vol 33 (4) ◽  
pp. 210-226 ◽  
Author(s):  
I. L. Al-Qadi ◽  
M. A. Elseifi ◽  
P. J. Yoo ◽  
I. Janajreh
Keyword(s):  
Carrying Capacity ◽  
Material Properties ◽  
Three Dimensional ◽  
Fe Analysis ◽  
Load Carrying Capacity ◽  
Inflation Pressure ◽  
3D Finite Element ◽  
Load Carrying ◽  
Pavement Damage ◽  
New Generation

Abstract The objective of this study was to quantify pavement damage due to a conventional (385/65R22.5) and a new generation of wide-base (445/50R22.5) tires using three-dimensional (3D) finite element (FE) analysis. The investigated new generation of wide-base tires has wider treads and greater load-carrying capacity than the conventional wide-base tire. In addition, the contact patch is less sensitive to loading and is especially designed to operate at 690kPa inflation pressure at 121km/hr speed for full load of 151kN tandem axle. The developed FE models simulated the tread sizes and applicable contact pressure for each tread and utilized laboratory-measured pavement material properties. In addition, the models were calibrated and properly validated using field-measured stresses and strains. Comparison was established between the two wide-base tire types and the dual-tire assembly. Results indicated that the 445/50R22.5 wide-base tire would cause more fatigue damage, approximately the same rutting damage and less surface-initiated top-down cracking than the conventional dual-tire assembly. On the other hand, the conventional 385/65R22.5 wide-base tire, which was introduced more than two decades ago, caused the most damage.

scholarly journals Charge algebra in Al(A)dSn spacetimes

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Adrien Fiorucci ◽  
Romain Ruzziconi
Keyword(s):  
Boundary Conditions ◽  
Dirichlet Boundary ◽  
Three Dimensional ◽  
Dirichlet Boundary Conditions ◽  
Boundary Structure ◽  
Asymptotic Symmetry ◽  
Renormalization Procedure ◽  
Field Dependent ◽  
Odd Dimensions

Abstract The gravitational charge algebra of generic asymptotically locally (A)dS spacetimes is derived in n dimensions. The analysis is performed in the Starobinsky/Fefferman-Graham gauge, without assuming any further boundary condition than the minimal falloffs for conformal compactification. In particular, the boundary structure is allowed to fluctuate and plays the role of source yielding some symplectic flux at the boundary. Using the holographic renormalization procedure, the divergences are removed from the symplectic structure, which leads to finite expressions. The charges associated with boundary diffeomorphisms are generically non-vanishing, non-integrable and not conserved, while those associated with boundary Weyl rescalings are non-vanishing only in odd dimensions due to the presence of Weyl anomalies in the dual theory. The charge algebra exhibits a field-dependent 2-cocycle in odd dimensions. When the general framework is restricted to three-dimensional asymptotically AdS spacetimes with Dirichlet boundary conditions, the 2-cocycle reduces to the Brown-Henneaux central extension. The analysis is also specified to leaky boundary conditions in asymptotically locally (A)dS spacetimes that lead to the Λ-BMS asymptotic symmetry group. In the flat limit, the latter contracts into the BMS group in n dimensions.

scholarly journals Boundary conditions in topological AdS4/CFT3

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Pietro Benetti Genolini ◽  
Matan Grinberg ◽  
Paul Richmond
Keyword(s):  
Field Theory ◽  
Free Energy ◽  
Boundary Conditions ◽  
Smooth Solution ◽  
Three Dimensional ◽  
Field Theories ◽  
Legendre Transformation ◽  
Generating Functional ◽  
Holographic Duals

Abstract We revisit the construction in four-dimensional gauged Spin(4) supergravity of the holographic duals to topologically twisted three-dimensional $$ \mathcal{N} $$ N = 4 field theories. Our focus in this paper is to highlight some subtleties related to preserving supersymmetry in AdS/CFT, namely the inclusion of finite counterterms and the necessity of a Legendre transformation to find the dual to the field theory generating functional. Studying the geometry of these supergravity solutions, we conclude that the gravitational free energy is indeed independent from the metric of the boundary, and it vanishes for any smooth solution.

scholarly journals Bootstrapping boundary-localized interactions

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Connor Behan ◽  
Lorenzo Di Pietro ◽  
Edoardo Lauria ◽  
Balt C. van Rees
Keyword(s):  
Boundary Condition ◽  
Scalar Field ◽  
Boundary Conditions ◽  
Parameter Space ◽  
Three Dimensional ◽  
Conformal Boundary ◽  
Dimensional Boundary ◽  
Dirichlet And Neumann Conditions ◽  
Boundary Fields ◽  
Boundary Dynamics

Abstract We study conformal boundary conditions for the theory of a single real scalar to investigate whether the known Dirichlet and Neumann conditions are the only possibilities. For this free bulk theory there are strong restrictions on the possible boundary dynamics. In particular, we find that the bulk-to-boundary operator expansion of the bulk field involves at most a ‘shadow pair’ of boundary fields, irrespective of the conformal boundary condition. We numerically analyze the four-point crossing equations for this shadow pair in the case of a three-dimensional boundary (so a four-dimensional scalar field) and find that large ranges of parameter space are excluded. However a ‘kink’ in the numerical bounds obeys all our consistency checks and might be an indication of a new conformal boundary condition.

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