Semi-Analytical Model to Predict the Elastic Post-buckling Response of Axially Compressed Cylindrical Shells with Tailored Distributed Stiffness

2021 ◽  
pp. 1-29
Author(s):  
Ali Imani Azad ◽  
Rigoberto Burgueño
Keyword(s):  
Analytical Model ◽  
Local Buckling ◽  
Radial Deformation ◽  
Governing Equations ◽  
Radial Functions ◽  
Nonlinear Springs ◽  
Proposed Model ◽  
Post Buckling ◽  
3D Printed ◽  
Axial Response

Abstract This study introduces an approximate analytical model to predict the post-buckling response of cylinders with tailored nonuniform distributed stiffness. The shell's wall thickness, and thus its stiffness, is tailored so as to obtain multiple controlled elastic local buckling events when the cylinder is subjected to uniform axial compression. The proposed model treats cylinder segments of different stiffness as individual panels and combines their response by considering them as connected linear or nonlinear springs. The governing equations for the panels are formulated using von Karman's theory and solved by Galerkin's approximate method for a predefined radial deformation. Radial deformation functions are used to improve the model's accuracy and results show that the model's accuracy increases significantly with the number of considered radial functions. The model's predicted axial response for different cylinders are compared to results from experiments on 3D printed samples. Results indicate that this model accurately predicts the order of the buckling events while the buckling forces from the model are higher than those measured experimentally.

Analytical Model for Corrosion Penetration Depth at Cover Cracking in RC Structures

2008 ◽  
Vol 400-402 ◽  
pp. 227-232 ◽  
Author(s):  
Hua Song ◽  
Di Tao Niu ◽  
Si Yuan Liu
Keyword(s):  
Analytical Model ◽  
Corrosion Products ◽  
Residual Service Life ◽  
Load Carrying Capacity ◽  
Governing Equations ◽  
Rc Structures ◽  
Cover Cracking ◽  
Proposed Model ◽  
Load Carrying ◽  
Residual Service

Corrosion products which occupy much greater volume accumulate, and generate expansive pressures on the surrounding concrete. The pressure builds up and eventually leads to the cover cracking of the structures. The cracking accelerates further corrosion and leads to the loss of the bond strength and the load carrying capacity. Corrosion cracking would reveal the reducing of the residual service life of the corrosion-affected structures. In this paper, an analytical model is proposed to predict the critical corrosion penetration at cover cracking in RC structures based on the crack process. An attempt has been made to develop the model by considering material properties of the surrounding concrete and expansive corrosion products. The problem is established as a boundary-value problem and the governing equations are expressed in terms of the radial displacement. The analytical predictions of the proposed model have also been in agreement with the available experimental data.

Thermal Post-Buckling Analysis of Functionally Graded Composite Plates with Nonlinear Aerodynamic Forces

2010 ◽  
Vol 123-125 ◽  
pp. 280-283
Author(s):  
Chang Yull Lee ◽  
Ji Hwan Kim
Keyword(s):  
Material Properties ◽  
Numerical Solutions ◽  
Virtual Work ◽  
Shear Deformation Theory ◽  
Composite Plates ◽  
Buckling Analysis ◽  
Functionally Graded ◽  
Governing Equations ◽  
Functionally Graded Composite ◽  
Post Buckling

The post-buckling of the functionally graded composite plate under thermal environment with aerodynamic loading is studied. The structural model has three layers with ceramic, FGM and metal, respectively. The outer layers of the sandwich plate are different homogeneous and isotropic material properties for ceramic and metal. Whereas the core is FGM layer, material properties vary continuously from one interface to the other in the thickness direction according to a simple power law distribution in terms of the volume fractions. Governing equations are derived by using the principle of virtual work and numerical solutions are solved through a finite element method. The first-order shear deformation theory and von-Karman strain-displacement relations are based to derive governing equations of the plate. Aerodynamic effects are dealt by adopting nonlinear third-order piston theory for structural and aerodynamic nonlinearity. The Newton-Raphson iterative method applied for solving the nonlinear equations of the thermal post-buckling analysis

scholarly journals Analytical Model for Estimating the Impact of Changing the Nominal Power Parameter in LTE

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
A. B. Vallejo-Mora ◽  
M. Toril ◽  
S. Luna-Ramírez ◽  
M. Regueira ◽  
S. Pedraza
Keyword(s):  
Analytical Model ◽  
Mobile Networks ◽  
Radio Resource Management ◽  
Estimation Accuracy ◽  
Model Assessment ◽  
Power Parameter ◽  
Management Procedure ◽  
Proposed Model ◽  
A Cell ◽  
The Impact

UpLink Power Control (ULPC) is a key radio resource management procedure in mobile networks. In this paper, an analytical model for estimating the impact of increasing the nominal power parameter in the ULPC algorithm for the Physical Uplink Shared CHannel (PUSCH) in Long Term Evolution (LTE) is presented. The aim of the model is to predict the effect of changing the nominal power parameter in a cell on the interference and Signal-to-Interference-plus-Noise Ratio (SINR) of that cell and its neighbors from network statistics. Model assessment is carried out by means of a field trial where the nominal power parameter is increased in some cells of a live LTE network. Results show that the proposed model achieves reasonable estimation accuracy, provided uplink traffic does not change significantly.

Zero Gravity Validation of Smart Aperture Antennas

1999 ◽  
Author(s):  
Hwan-Sik Yoon ◽  
Gregory Washington
Keyword(s):  
Spherical Shell ◽  
Analytical Model ◽  
Stress Function ◽  
Spherical Shape ◽  
Element Model ◽  
Shallow Spherical Shell ◽  
Zero Gravity ◽  
Governing Equations ◽  
Homogeneous Solutions ◽  
Calculated Stress

Abstract In this study, a smart aperture antenna of spherical shape is modeled and experimentally verified. The antenna is modeled as a shallow spherical shell with a small hole at the apex for mounting. Starting from five governing equations of the shallow spherical shell, two governing equations are derived in terms of a stress function and the axial deflection using Reissner’s approach. As actuators, four PZT strip actuators are attached along the meridians separated by 90 degrees respectively. The forces developed by the actuators are considered as distributed pressure loads on the shell surface instead of being applied as boundary conditions like previous studies. This new way of applying the actuation force necessitates solving for the particular solutions in addition to the homogeneous solutions for the governing equations. The amount of deflections is evaluated from the calculated stress function and the axial deflection. In addition to the analytical model, a finite element model is developed to verify the analytical model on the various surface positions of the reflector. Finally, an actual working model of the reflector is built and tested in a zero gravity environment, and the results of the theoretical model are verified by comparing them to the experimental data.

An analytical model for predicting the shear strength of unsaturated soils

2022 ◽  
pp. 1-57
Author(s):  
Tuan A. Pham ◽  
Melis Sutman
Keyword(s):  
Shear Strength ◽  
Analytical Model ◽  
Unsaturated Soils ◽  
High Performance ◽  
Micromechanical Model ◽  
Experimental Studies ◽  
Stress Equilibrium ◽  
Proposed Model ◽  
New Equation ◽  
Multi Phase

The prediction of shear strength for unsaturated soils remains to be a significant challenge due to their complex multi-phase nature. In this paper, a review of prior experimental studies is firstly carried out to present important pieces of evidence, limitations, and some design considerations. Next, an overview of the existing shear strength equations is summarized with a brief discussion. Then, a micromechanical model with stress equilibrium conditions and multi-phase interaction considerations is presented to provide a new equation for predicting the shear strength of unsaturated soils. The validity of the proposed model is examined for several published shear strength data of different soil types. It is observed that the shear strength predicted by the analytical model is in good agreement with the experimental data, and get high performance compared to the existing models. The evaluation of the outcomes with two criteria, using average relative error and the normalized sum of squared error, proved the effectiveness and validity of the proposed equation. Using the proposed equation, the nonlinear relationship between shear strength, saturation degree, volumetric water content, and matric suction are observed.

scholarly journals Predictive System of COVID -19 Using Response Based Analytical Model

2021 ◽  
pp. 05-10
Author(s):  
Pallavi Mirajkar ◽  
Rupali Dahake
Keyword(s):  
Analytical Model ◽  
Medical Services ◽  
The Novel ◽  
Response Data ◽  
Proposed Model ◽  
The World

The novel COVID sickness 2019 (COVID-19) pandemic caused by the SARS-CoV-2 keeps on representing a serious and vital threat to worldwide health. This pandemic keeps on testing clinical frameworks around the world in numerous viewpoints, remembering sharp increments in requests for clinic beds and basic deficiencies in clinical equipments, while numerous medical services laborers have themselves been infected. We have proposed analytical model that predicts a positive SARS-CoV-2 infection by considering both common and severe symptoms in patients. The proposed model will work on response data of all individuals if they are suffering from various symptoms of the COVID-19. Consequently, proposed model can be utilized for successful screening and prioritization of testing for the infection in everyone.

An Analytical Model to Predict the Push-Out Capacity of Mortar from Rock Block

2011 ◽  
Vol 250-253 ◽  
pp. 2396-2406
Author(s):  
Shu Tong Yang
Keyword(s):  
Analytical Model ◽  
Interfacial Shear Stress ◽  
Tensile Load ◽  
Interfacial Shear ◽  
Rock Block ◽  
Ground Anchors ◽  
Proposed Model ◽  
Wide Range ◽  
Rock Interface ◽  
Push Out

Ground anchors have been very practical in a wide range of geotechnical structures. Good bond properties at the anchor-mortar and mortar-rock interfaces can ensure transmitting an applied tensile load to a load bearing structure efficiently. The bond performance between the mortar and rock is necessary to be studied. A push-out test of mortar from rock block can be used to analyze the interfacial properties between the two materials. In this paper, an analytical model is proposed to determine the push-out capacity of mortar from rock block. Based on the deformation compatibility at the interface, the compressive stress in the mortar and the interfacial shear stress at the mortar-rock interface are formulated at different loading stages. By modeling interfacial debonding as an interfacial shear crack, the push-out load is then expressed as a function of the interfacial crack length. In virtue of the Lagrange Multiplier Method, the maximum push-out load is determined. The validity of the proposed model is verified with the experimental results. It can be concluded that if the interfacial parameters at the mortar-rock interface are obtained, the push-out capacity of mortar from rock block can be accurately determined using the proposed model. The proposed solution in this paper would provide a good theoretical basis in evaluating the stability of ground anchors in practice.

Post-Buckling of Piezoelectric Thin Plates

2015 ◽  
Vol 15 (07) ◽  
pp. 1540020 ◽  
Author(s):  
Michael Krommer ◽  
Hans Irschik
Keyword(s):  
Nonlinear Partial Differential Equation ◽  
Nonlinear Behavior ◽  
Dirichlet Boundary Conditions ◽  
Thin Plates ◽  
Governing Equations ◽  
Simply Supported ◽  
Buckling Behavior ◽  
Single Term ◽  
Post Buckling ◽  
Special Case

In the present paper, the geometrically nonlinear behavior of piezoelastic thin plates is studied. First, the governing equations for the electromechanically coupled problem are derived based on the von Karman–Tsien kinematic assumption. Here, the Berger approximation is extended to the coupled piezoelastic problem. The general equations are then reduced to a single nonlinear partial differential equation for the special case of simply supported polygonal edges. The nonlinear equations are approximated by using a problem-oriented Ritz Ansatz in combination with a Galerkin procedure. Based on the resulting equations the buckling and post-buckling behavior of a polygonal simply supported plate is studied in a nondimensional form, where the special geometry of the polygonal plate enters via the eigenvalues of a Helmholtz problem with Dirichlet boundary conditions. Single term as well as multi-term solutions are discussed including the effects of piezoelectric actuation and transverse force loadings upon the solution. Novel results concerning the buckling, snap through and snap buckling behavior are presented.

Prediction of Thrust and Torque for Multifacet Drills (MFD)

1994 ◽  
Vol 116 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Horng-Tsann Huang ◽  
Cheng-I Weng ◽  
Chao-Kuang Chen
Keyword(s):  
Analytical Model ◽  
Theoretical Method ◽  
Cutting Mechanics ◽  
Drilling Performance ◽  
Proposed Model ◽  
Wide Range ◽  
Drill Point ◽  
Thrust And Torque

A multifacet drill (MFD), developed around 1953, has been used to improve the drilling performance by modifying the drill point geometry. A theoretical method for predicting the thrust and torque for an MFD is developed on the basis of the cutting mechanics for a conventional drill. Experiments show the proposed model is quite satisfactory for a wide range of applications. Also, from the analytical model the effects of the major features of the drill point geometry on thrust and torque can be studied.

scholarly journals A Coupled, Semi-Numerical Model for Thermal Analysis of Medium Frequency Transformer

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 328 ◽  
Author(s):  
Haonan Tian ◽  
Zhongbao Wei ◽  
Sriram Vaisambhayana ◽  
Madasamy Thevar ◽  
Anshuman Tripathi ◽  
...  
Keyword(s):  
Numerical Model ◽  
Analytical Model ◽  
Electromagnetic Analysis ◽  
Medium Frequency ◽  
Fluid Analysis ◽  
Fluid Behavior ◽  
Proposed Model ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Thermal Fluid Analysis

Medium-frequency (MF) transformer has gained much popularity in power conversion systems. Temperature control is a paramount concern, as the unexpected high temperature declines the safety and life expectancy of transformer. The scrutiny of losses and thermal-fluid behavior are thereby critical for the design of MF transformers. This paper proposes a coupled, semi-numerical model for electromagnetic and thermal-fluid analysis of MF oil natural air natural (ONAN) transformer. An analytical model that is based on spatial distribution of flux density and AC factor is exploited to calculate the system losses, while the thermal-hydraulic behavior is modelled numerically leveraging the computational fluid dynamics (CFD) method. A close-loop iterative framework is formulated by coupling the analytical model-based electromagnetic analysis and CFD-based thermal-fluid analysis to address the temperature dependence. Experiments are performed on two transformer prototypes with different conductor types and physical geometries for validation purpose. Results suggest that the proposed model can accurately model the AC effects, losses, and the temperature rises at different system components. The proposed model is computationally more efficient than the full numerical method but it reserves accurate thermal-hydraulic characterization, thus it is promising for engineering utilization.

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