A Survey With Numerical Assessment of Classical and Refined Theories for the Analysis of Sandwich Plates

2008 ◽  
Vol 62 (1) ◽  
Author(s):  
E. Carrera ◽  
S. Brischetto
Keyword(s):  
Higher Order ◽  
Benchmark Problems ◽  
Geometrical Parameters ◽  
Closed Form Solutions ◽  
Simply Supported ◽  
Numerical Assessment ◽  
Shell Analysis ◽  
Out Of Plane ◽  
The Face ◽  
Free Vibration Response

A large variety of plate theories are described and assessed in the present work to evaluate the bending and vibration of sandwich structures. A brief survey of available works is first given. Such a survey includes significant review papers and latest developments on sandwich structure modelings. The kinematics of classical, higher order, zigzag, layerwise, and mixed theories is described. An exhaustive numerical assessment of the whole theories is provided in the case of closed form solutions of simply supported panels made of orthotropic layers. Reference is made to the unified formulation that has recently been introduced by the first author for a plate/shell analysis. Attention has been given to displacements, stresses (both in-plane and out-of-plane components), and the free vibration response. Only simply supported orthotropic panels loaded by a transverse distribution of bisinusoidal pressure have been analyzed. Five benchmark problems are treated. The accuracy of the plate theories is established with respect to the length-to-thickness-ratio (LTR) geometrical parameters and to the face-to-core-stiffness-ratio (FCSR) mechanical parameters. Two main sources of error are outlined, which are related to LTR and FCSR, respectively. It has been concluded that higher order theories (HOTs) can be conveniently used to reduce the error due to LTR in thick plate cases. But HOTs are not effective in increasing the accuracy of the classical theory analysis whenever the error is caused by increasing FCSR values; layerwise analysis becomes mandatory in this case.

scholarly journals Peridynamic Formulation for Higher-Order Plate Theory

2020 ◽  
Author(s):  
Zhenghao Yang ◽  
Erkan Oterkus ◽  
Selda Oterkus
Keyword(s):  
Boundary Conditions ◽  
Plate Theory ◽  
Mixed Boundary ◽  
Lagrange Equation ◽  
Mixed Boundary Conditions ◽  
Higher Order ◽  
Benchmark Problems ◽  
Element Analysis ◽  
Simply Supported ◽  
Peridynamic Model

AbstractIn this study, a new peridynamic model is presented for higher-order plate theory. The formulation is derived by using Euler-Lagrange equation and Taylor’s expansion. The formulation is verified by considering two benchmark problems including simply supported and clamped plates subjected to transverse loading. Moreover, mixed (simply supported-clamped) boundary conditions are also considered to investigate the capability of the current formulation for mixed boundary conditions. Peridynamic results are compared with finite element analysis results and a very good agreement was obtained between the two approaches.

scholarly journals Alzheimer’s Disease Progressively Reduces Visual Functional Network Connectivity

2021 ◽  
pp. 1-14
Author(s):  
Jie Huang ◽  
Paul Beach ◽  
Andrea Bozoki ◽  
David C. Zhu
Keyword(s):  
Visual Cortex ◽  
Lower Order ◽  
Resting State ◽  
Visual Processing ◽  
Network Connectivity ◽  
Higher Order ◽  
Functional Network ◽  
Functional Networks ◽  
The Face ◽  
Processing Network

Background: Postmortem studies of brains with Alzheimer’s disease (AD) not only find amyloid-beta (Aβ) and neurofibrillary tangles (NFT) in the visual cortex, but also reveal temporally sequential changes in AD pathology from higher-order association areas to lower-order areas and then primary visual area (V1) with disease progression. Objective: This study investigated the effect of AD severity on visual functional network. Methods: Eight severe AD (SAD) patients, 11 mild/moderate AD (MAD), and 26 healthy senior (HS) controls undertook a resting-state fMRI (rs-fMRI) and a task fMRI of viewing face photos. A resting-state visual functional connectivity (FC) network and a face-evoked visual-processing network were identified for each group. Results: For the HS, the identified group-mean face-evoked visual-processing network in the ventral pathway started from V1 and ended within the fusiform gyrus. In contrast, the resting-state visual FC network was mainly confined within the visual cortex. AD disrupted these two functional networks in a similar severity dependent manner: the more severe the cognitive impairment, the greater reduction in network connectivity. For the face-evoked visual-processing network, MAD disrupted and reduced activation mainly in the higher-order visual association areas, with SAD further disrupting and reducing activation in the lower-order areas. Conclusion: These findings provide a functional corollary to the canonical view of the temporally sequential advancement of AD pathology through visual cortical areas. The association of the disruption of functional networks, especially the face-evoked visual-processing network, with AD severity suggests a potential predictor or biomarker of AD progression.

Analysis of Bifurcations for a Functionally Graded Materials Plate

2013 ◽  
Vol 300-301 ◽  
pp. 988-991 ◽  
Author(s):  
Wei Qin Yu
Keyword(s):  
Functionally Graded Materials ◽  
Functionally Graded ◽  
Periodic Motions ◽  
Graded Materials ◽  
Normal Form Theory ◽  
Closed Form Solutions ◽  
Simply Supported ◽  
Form Theory ◽  
Bifurcation And Stability ◽  
Numerical Approaches

Using the analytical and numerical approaches, the nonlinear dynamic behaviors in the vicinity of a compound critical point are studied for a simply supported functionally graded materials (FGMs) rectangular plate. Normal form theory, bifurcation and stability theory are used to find closed form solutions for equilibria and periodic motions. Stability conditions of these solutions are obtained explicitly and critical boundaries are also derived. Finally, numerical results are presented to confirm the analytical predictions

scholarly journals Deep learning for pose-invariant face detection in unconstrained environment

2019 ◽  
Vol 9 (1) ◽  
pp. 577
Author(s):  
Shivkaran Ravidas ◽  
M. A. Ansari
Keyword(s):  
Neural Network ◽  
Recent Past ◽  
Probabilistic Measure ◽  
Low Level ◽  
Face Images ◽  
Analysis Experiment ◽  
Out Of Plane ◽  
The Face ◽  
In The Wild ◽  
Visual Matching

<span lang="EN-US">In the recent past, convolutional neural networks (CNNs) have seen resurgence and have performed extremely well on vision tasks.  Visually the model resembles a series of layers each of which is processed by a function to form a next layer. It is argued that CNN first models the low level features such as edges and joints and then expresses higher level features as a composition of these low level features. The aim of this paper is to detect multi-view faces using deep convolutional neural network (DCNN). Implementation, detection and retrieval of faces will be obtained with the help of direct visual matching technology. Further, the probabilistic measure of the similarity of the face images will be done using Bayesian analysis. Experiment detects faces with ±90 degree out of plane rotations. Fine tuned AlexNet is used to detect pose invariant faces. For this work, we extracted examples of training from AFLW (Annotated Facial Landmarks in the Wild) dataset that involve 21K images with 24K annotations of the face.</span>

scholarly journals Peridynamic Higher-Order Beam Formulation

2020 ◽  
Author(s):  
Zhenghao Yang ◽  
Erkan Oterkus ◽  
Selda Oterkus
Keyword(s):  
Finite Element Method ◽  
Cantilever Beam ◽  
Higher Order ◽  
Point Load ◽  
Transverse Displacement ◽  
Lagrange Equations ◽  
Concentrated Load ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Good Agreement

Abstract In this study, a novel higher-order peridynamic beam formulation is presented. The formulation is obtained by using Euler-Lagrange equations and Taylor’s expansion. To demonstrate the capability of the presented approach, several different beam configurations are considered including simply supported beam subjected to distributed loading, simply supported beam with concentrated load, clamped-clamped beam subjected to distributed loading, cantilever beam subjected to a point load at its free end and cantilever beam subjected to a moment at its free end. Transverse displacement results along the beam obtained from peridynamics and finite element method are compared with each other and very good agreement is obtained between the two approaches.

A Review of Temperature Reduction Methods in Codes and Standards for Pipe Supports

2020 ◽  
Author(s):  
Alex Mayes ◽  
Phillip Wiseman ◽  
Kshitij P. Gawande
Keyword(s):  
Heat Transfer ◽  
Computational Models ◽  
Thermal Stresses ◽  
Geometrical Parameters ◽  
Atmospheric Conditions ◽  
Closed Form Solutions ◽  
Temperature Reduction ◽  
Reduction Methods ◽  
American Society ◽  
Transient Thermal

Abstract American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, Division 1, Subsection NF, Subparagraph NF-3121.11 does not require that thermal stresses in supports be evaluated. Historically, pipe support engineers have not been concerned with thermal stresses of pipe and component supports, but determining material temperature limits and allowable stresses have been a major role in designing and analyzing supports. Thus, heat transfer is often investigated in finding the temperature of pipe supports and parts of pipe supports that are not in direct contact with pipe or pipe components. There are also other Codes and standards that permit a reduction of temperature away from the outer surface of pipe or pipe components. In some but not all cases, Codes and standards explicitly address reduction of temperature for applications of utilizing thermal insulation. Additionally, the temperature distribution is established by specific geometrical parameters and their respective equations for employment by the pipe support engineer. These reductions are explored by utilizing fundamentals of heat transfer. Additionally, steady-state and transient thermal Finite Element Analyses (FEA) are used to establish computational models of simple geometric bodies in a range of atmospheric conditions. The effects of insulation on the thermal distribution are also represented through closed form solutions and FEA. The results of these analyses allow for assessment of, and recommendations for, the treatment of temperature reduction in Codes and standards.

Non-linear thermo-mechanical cylindrical bending of functionally graded plates

2008 ◽  
Vol 222 (3) ◽  
pp. 305-318 ◽  
Author(s):  
F Fallah ◽  
A Nosier
Keyword(s):  
Boundary Conditions ◽  
Volume Fraction ◽  
Functionally Graded ◽  
Power Law Distribution ◽  
Cylindrical Bending ◽  
Closed Form Solutions ◽  
Simply Supported ◽  
Fg Plates ◽  
Non Linear ◽  
The One

Based on the first-order non-linear von Karman theory, cylindrical bending of functionally graded (FG) plates subjected to mechanical, thermal, and combined thermo-mechanical loadings are investigated. Analytical solutions are obtained for an FG plate with various clamped and simply-supported boundary conditions. The closed form solutions obtained are very simple to be used in design purposes. The material properties are assumed to vary continuously through the thickness of the plate according to a power-law distribution of the volume fraction of the constituents. The effects of non-linearity, material property, and boundary conditions on various response quantities are studied and discussed. It is found that linear analysis is inadequate for analysis of simply-supported FG plates even in the small deflection range especially when thermal load is present. Also it is shown that bending—extension coupling can not be seen in response quantities of clamped FG plates. Also an exact solution is developed for the one-dimensional heat conduction equation with variable heat conductivity coefficient.

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