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haddadpour--hassan
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Evaluating the Method of Component Mode Synthesis (CMS)for a Central Beam a with Four Side Beams
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Mohammad Navazi, Hossein (Supervisor)
Abstract
This research investigates the possibility of using the component mode synthesis (CMS) method in experimentation. It should be noted that the original idea for this project originated from an industrial problem. The main issue in this problem was the lack of sufficient equipment to conduct tests on very large structural modes and the high computational cost for their analysis. Therefore, a test platform was constructed using a scaled-down sample (approximately 1:25) with connections that closely resembled real connections. This assembly was then tested separately, and the results were compared with analytical analyses. After updating and correcting the model in several stages, the structure...
Analysis of Sandwich Beam Vibration Due to Moving Mass
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Asgari, Mojtaba (Co-Supervisor)
Abstract
In this research, mathematical modeling, deriving equations of motion, solving equations and analyzing the response of motion vibrations of a moving mass with constant speed on a sandwich beam have been discussed. The sandwich beam consists of three layers, the middle layer of which is made of viscoelastic material, and the upper and lower layers are the Euler-Bernoulli beam model.At first, this sandwich beam is mathematically modeled, This mathematical modeling includes all the specifications of the system to obtain the equations that govern the behavior of the system. Then, the displacement field of the system has been extracted and the equations of motion of the system have been obtained...
Non-Linear Aeroelastic Analysis of Three-Layered Plates with Magneto-Rheological Fluid Core in Supersonic Airflow
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
This study is a comprehensive analysis on the nonlinear vibration of a sandwich plate containing magnetorheological (MR) fluid as the core layer. The nonlinear aeroelastic analysis of the structure is also discussed to determine the flutter boundaries. In this study, the numerical Generalized Differential Quadrature (GDQ) method is applied to investigate the free vibration analysis of a sandwich plate with a MR fluid core. The classical thin plate theory (CPT) and the First-order Shear Deformation Theory (FSDT) are assumed for face layers and core layer, respectively. These theories along with Von-Karman kinematic formulations are incorporated to extract governing equations. The equations of...
Structural Design of a Launch Vehicle with Reusable First Stage
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
Aerodynamics loads and aeroheating during reentry, are one of the challenging issues in designing One of the main challenges in the design and application of reusable spacecrafts is the aerodynamic and thermal loads acting on their structures during reentry into the atmosphere. For this reason, all the concepts/prototypes presented in the 20th century were either not fully reusable, or were partially canceled, or did not have economic justification. In this report, the aerodynamic loads on the first stage of a launch vehicle during the launch and return phases have been investigated. Due to the fact that the main part of the first stage of the vehicle includes fuel and oxidizer tanks, the...
Investigation of Aero-Servo-Elasticity Behavior of Airship by Considering the Torsional Mode of the Fuselage
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
In this research, with the help of a comprehensive dynamic model, the stability, control, dynamics and twisting of airships with flexible bodies and beams have been investigated. For the first time, the influence of the twisting mode of the body on the dynamic behavior and control of the airship has been investigated by considering the pressure drop inside the body. By obtaining the terms of kinetic energy and the potential of the body and beams, the governing equations of the bird have been extracted and with the help of mass integrals, the velocity of the body and beams has been obtained. The answer to this non-linear dynamic couple problem, due to the existence of two types of dynamic...
Vibration and Stability Analysis of a Rotor with Nonlinear Bearings
, Ph.D. Dissertation Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Mohammad Navazi, Hossein (Supervisor)
Abstract
In the present study, the nonlinear vibrations of the rotor on the nonlinear bearing have been studied by the multiple scale method. To achieve this goal, Jeffcott models, two degrees of freedom and rotating Euler-Bernoulli beam have been used as rotors and insulators and nonlinear tilting-bearing bearings have been used as supports.To better understand the importance of the supports in the analysis of rotating systems, the rotor joints with isolates with high static stiffness and low dynamic stiffness have been considered and the dynamic behavior of the system has been studied using the multiple scale method. The results of this study showed that this type of nonlinear isolator has a good...
Aeroelastic Analysis of Sandwich Plates with Viscoelastic Core and Functionally Graded Materials in Supersonic Flow
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
This study investigates the aeroelastic instability of functionally graded sandwich plate with viscoelastic core in supersonic airflow. The classical plate theory, first order shear deformation theory, Hamilton's principle and linear first-order piston theory have been employed to extract the governing equations of motion of the structure. The Ritz method and State space notation is used to solve the derived equations and identify the instability boundary of the sandwich plate with simply-supported boundary conditions. The derived are solved using a computer program which is validated and verified by comparing the results with available literature. Our attention is focused on analyzing the...
Dynamics, Stability, and Aero-servo-elasticity of Airships with Flexible Body and Fins
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
In this research, the dynamics, aero-elasticity, and control of an airship with a flexible body hull and fins are investigated. The flexible airship is modeled as a combination of several beams with specific boundary conditions. So that the dynamics and vibration of its body hull and fins can be taken into account regarding the aerodynamic, gravity, aerostatic, and control input forces. The governing equations of motion of the system are derived by using the velocity of an arbitrary point on each component and integration over the component and substituting them into the Euler-Lagrange equations in a body frame. Afterward, the added mass acting on the hull is calculated. Then, a perturbation...
Vibration Analysis of Spur and Helical Geared-rotor System under Residual Shaft Bow Effect
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
The purpose of this study is to establish a lateral-torsional-axial dynamic model for spur and helical geared rotor systems subject to shaft bow manufacturing error. Timoshinko shaft element, elastic bearings and rigid disks used to simulate different element in the model. Tooth contacts is modeled with linear spring and damper along the pressure line.Results show that the vibration pattern of the unbalanced load and shaft bow effect is different. These obtained patterns might help with the fault diagnostics of rotating machinery. The vibration will be lowest if the unbalanced load and the shaft bow amplitude locates out of phase. The previous researches show that different pattern of the...
Investigation of Nonlinear Vibration and Stability Analysis of Rotor with Journal and Axial Bearings
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
Vibrational analysis of a rotor with journal and axial bearings requires modelling of forces acted on the journal of the rotor by the bearings. The aim of the present research firstly is to extract the linear dynamic coefficients of the tilting-pad thrust bearing and then to analyze nonlinear vibrations and stability of the rotor. By use of the partial derivative method along with Perturbation method the linear dynamic coefficients are calculated. Full dynamic coefficients are extracted by solving Reynolds equation and its perturbed forms using finite difference method. Dynamic equilibrium equations of pad are used to obtain reduced-order dynamic coefficients. In the following the equations...
Dynamic Response Analysis of a Three-Layered Circular Plate with Magnetorheological Fluid Core Under Low Velocity Impact Loading
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
Various public transportation types, e.g., Trains, Buses, and Airplanes, are susceptible to damages made by the impacts of the external objects, which are typically classified as low to medium velocity impacts. This problem reveals the significance of investigating the effects of impact on thin-walled structures, which are the main components of these vehicles' bodies. Owing to the controllable rheological properties of the Magnetorheological fluid with respect to the magnetic field, it can be utilized to control the structure exposed to impact adaptively and minimize the damages. Due to this purpose, sandwich structures such as sandwich beams and plates, thanks to their extended response...
Vibration and Aeroelastic Stability Analysis of Sandwich Turbomachinery Blade with Magnetorheological Elastomer Core
, Ph.D. Dissertation Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Mohammad Navazi, Hossein (Co-Supervisor)
Abstract
This dissertaion deals with the vibration and aeroelasticity analysis of a turbomachinery cascade with Magnetorheological Elastomer (MRE) based sandwich blades. At first, bending vibration of the rotary blades equipped with an MRE core based on the three-layered sandwich beam theory have been studied in the flexural and edgewise directions. Further, the torsional vibration is investigated and the effects of different parameters such as the intensity of the magnetic field, rotating speed and the MRE layer thickness on the natural frequencies and loss factors of the system are studied. On the basis of the modeling obtained for the structural dynamics and based on the Whitehead's unsteady...
A Reduced Order Hydroelastic Analysis of 3D Hydrofoil Considering Partial Sheet Cavitation Effects
, Ph.D. Dissertation Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Dehghani Firouz-abad, Roohallah (Co-Supervisor)
Abstract
In this Thesis hydroelastic analysis of 3D hydrofoil is investigated while partial sheet cavitation effects are considered. To this aim, first steady cavity boundary must be recognized.This region is calculated by means of conventional iterative procedure, stood upon potential flow theorem. In the second step, the reduced order fluid dynamics equations are derived based on potential flow theorem along with finite element method. This procedure is done in a way that real time system of equations are derived and iterative algorithm of conventional methods is omitted. To this aim, it is assumed that amplitude and frequency of the body oscillations are altered so that the cavity length in...
investigation of the Effect of Piezo-Electric Patch on the Modal Properties and Flutter Speed of Turbomachine Blade
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
In order to investigaton of dynamics behavior and determination of the aeroelastic stability of the turbomachine blade. the turbomachine blade is modeled by using the beam model, taking into account all degrees of freedom, the effect of warping, rotation and seting angle. For aerodynamic modeling, the Smith and Whitehead models are used which are valid in subsonic flow. The validity of the derived formulation is confirmed through comparison with those obtained from the finite element software and the available results in the literature. Then, by using the state feedback controller, the effect of sensor and piezoelectric actuator on the vibrations reduction of the structure and increasing the...
Nonlinear Vibration Analysis of a Rotor with Nonlinear Pedestal by use of Jeffcott Model
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Dehghani Firouzabadi, Rouhollah (Supervisor)
Abstract
The present research aims to achieve two major objectives in the Rotordynamic phenomenon. The first one is to study the linear and nonlinear dynamic characteristics of tilting pad journal bearings and calculating their dynamic coefficients like damping and stiffness, and the second one, studies the linear and nonlinear behavior of rotors standing on nonlinear pedestal, say nonlinear tilting pad journal bearing. By use of Partial Derivative method along with Perturbation method the linear dynamic coefficients are calculated for three different model of tilting pad journal bearing and these results are validated with the results presented by previous researches. The presented procedure is...
Bending-torsional Stability and Vibrations of Beams Conveying Pulsating Flow in the Presence of Free Stream
, Ph.D. Dissertation Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Dehghani Firouzabadi, Rohollah (Co-Advisor)
Abstract
In the current study, stability and nonlinear vibration of bending-torsional extensible beams conveying internal pulsatile and uniform external flow are studied. The internal and external fluid flows are assumed to be incompressible and frictionless. Applying the extensibility to the pipe along its length and using the nonlinear Euler-Bernoulli beam model and including some appropriate additional assumptions, the 3D nonlinear equations of motion of a cantilevered composite pipe is obtained. In order to derive the equations governing the fluid-structure interaction, the internal flow effect is modeled as a distributed load along the pipe which contains the inertia, Coriolis and centrifugal...
Flutter Analysis Rotating Blade of a Turbo Machinery Made of Magneto Rheological Elastomer Core
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
This study considers the flutter analysis rotating blade of a turbo machinery made of magneto rheological elastomer core. The Smith theory is used for modeling the compressible subsonic flow. The classical Hamilton’s principle along with the assume mode method is used to set up the equations of motion. The validity of the derived formulation is confirmed through comparison with those obtained from the finite element software and the available results in the literature. Various parametric studies including the effects of applied magnetic field, core layer thicknesses, rotating speed, setting angle are examined for considered configuration of the rotating blade. The results show that the first...
Control of Cable Vibration under Rain-wind Induced Vibration with Magneto-rheologycal Jacketing
,
M.Sc. Thesis
Sharif University of Technology
;
Haddadpour, Hassan
(Supervisor)
Abstract
The present thesis follows two aims in the phenomenon of vibration and control of cable of cable-stayed bridge under rain-wind induced vibration (RWIV). The first one is to study the response of the cable and consequently the second one aims to control these vibrations that occurred in the cable. The assumed continuous cable has lateral, in plane bending (IP), out of plane bending (OOP) and torsion mode. The effect of rainfall on the cable has been modeled with mobile upper rivulet on the cable surface and the effect and shape of lower rivulet have been neglected. RWIV is not vortex-induced vibration (VIV), nor wake galloping, because the dominant frequency of RWIV is lower than VIV and...
Aeroelastic Analysis of Flying Wing Aircrafts
, M.Sc. Thesis Sharif University of Technology ; Dehghan Firouzabadi, Rouhollah (Supervisor) ; Haddadpour, Hassan (Supervisor)
Abstract
Purpose of this thesis is to discover the governing equation of Flying Wing aircrafts. In Flying Wing aircrafts crew, payload, fuel, and equipment are typically housed inside the main wing structure. A clean flying wing is sometimes presented as theoretically the most aerodynamically efficient (lowest drag) design configuration for a fixed wing aircraft. We assume Flying wing as plate. Achieve structural formulation needs to use modal deflections and put them in Lagrangian equations. In the right had side, pressure on flying wing can be found. To obtain air pressure on flying wing in this thesis, applying Quasi steady aerodynamic and Howe distribution is necessary. Applying this method on ...
Optimization of Actuators Position of a Low Aspect Ratio Variable-camber Wing and Derivation of Its Aerodynamic
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Rouhollah (Supervisor) ; Haddadpour, Hassan (Supervisor)
Abstract
Morphing concepts can potentially improve the performance and fuel consumption of modern aircrafts. Smart materials can reduce the weight and complexity, and also are of the best choices to improve efficiency and reliability for realizing morphing wings. Developing of a simple model and optimization of smart piezocomposite actuators position of a thin wing with variable camber is considered. The goal is to gain desired properties in incompressible subsonic regime. Lifting surfaces of a composite wing are simplified using shell model. Keeping the problem simple, a piezocomposite patch is used to change the shell curvature. Basic modes are extracted from FEM software and behavior of bimorph...