Control Research on Construction Excitation Frequency of Resonant Rubblization Machine

2011 ◽  
Vol 305 ◽  
pp. 394-397
Author(s):  
Xin Qiu ◽  
Qing Yang ◽  
Lan Yun Chen
Keyword(s):  
Natural Frequency ◽  
Elastic Foundation ◽  
Thin Plate ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Research Results ◽  
Vibration Theory ◽  
Fundamental Natural Frequency ◽  
Control Research

Based on the assumption of thin plate of elastic foundation and vibration theory, a method for calculating the fundamental natural frequency of cement slab is presented and the influence of slab dimension and foundation reaction modulus on the fundamental natural frequency of cement slab is discussed. As well, according to the analysis results of fundamental natural frequencies of typical cement pavements of China, the selected proposals of the excitation frequency of the resonant rubblization machine are presented. The research results provide a theory support to popularize resonant rubblization technology in overlaying and rebuilding engineering of the existed cement pavements in China.

Mechanics Mechanism Analysis of Concrete Pavement Resonant Rubblization

2015 ◽  
Vol 667 ◽  
pp. 365-369
Author(s):  
Peng Chen ◽  
Xin Qiu ◽  
Qing Zhu ◽  
Chan Chan Ouyang
Keyword(s):  
Boundary Condition ◽  
Natural Frequency ◽  
Elastic Foundation ◽  
Thin Plate ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Concrete Pavement ◽  
Mechanism Analysis ◽  
Vibration Theory ◽  
Fundamental Natural Frequency

Based on the assumption of thin plate of elastic foundation and vibration theory, a method for calculating the fundamental natural frequency of cement slab is presented and the certain relationship between the fundamental natural frequency of cement slab and cement slab boundary condition is discussed. As well, according to the analysis results of fundamental natural frequencies of the typical cement pavements of China, the selected proposals of the excitation frequency of the resonant rubblization machine are presented .The research results provide a theory support to popularize resonant rubblization technology in overlaying and rebuilding engineering of the existed cement pavements in China.

Maximizing the Fundamental Natural Frequency of Triangular Composite Plates

1996 ◽  
Vol 118 (2) ◽  
pp. 141-146 ◽  
Author(s):  
S. Abrate
Keyword(s):  
Natural Frequency ◽  
Material Properties ◽  
Composite Structures ◽  
Natural Frequencies ◽  
Ritz Method ◽  
Laminated Composite ◽  
Composite Plates ◽  
Mode Shapes ◽  
Fundamental Natural Frequency ◽  
Wide Range

While many advances were made in the analysis of composite structures, it is generally recognized that the design of composite structures must be studied further in order to take full advantage of the mechanical properties of these materials. This study is concerned with maximizing the fundamental natural frequency of triangular, symmetrically laminated composite plates. The natural frequencies and mode shapes of composite plates of general triangular planform are determined using the Rayleigh-Ritz method. The plate constitutive equations are written in terms of stiffness invariants and nondimensional lamination parameters. Point supports are introduced in the formulation using the method of Lagrange multipliers. This formulation allows studying the free vibration of a wide range of triangular composite plates with any support condition along the edges and point supports. The boundary conditions are enforced at a number of points along the boundary. The effects of geometry, material properties and lamination on the natural frequencies of the plate are investigated. With this stiffness invariant formulation, the effects of lamination are described by a finite number of parameters regardless of the number of plies in the laminate. We then determine the lay-up that will maximize the fundamental natural frequency of the plate. It is shown that the optimum design is relatively insensitive to the material properties for the commonly used material systems. Results are presented for several cases.

Natural frequency modulation of a kinematically redundant planar parallel robot

2021 ◽  
pp. 095440622110524
Author(s):  
Jiawei Gu ◽  
Zhijiang Xie ◽  
Jian Zhang ◽  
Yangjun Pi
Keyword(s):  
Natural Frequency ◽  
Frequency Modulation ◽  
Natural Frequencies ◽  
Vibration Suppression ◽  
Excitation Frequency ◽  
Parallel Robot ◽  
Modulation Method ◽  
Kinematic Redundancy ◽  
Resonance Amplitude ◽  
Searching Method

When a parallel robot is equipped with kinematic redundancy, it has sufficient capabilities of natural frequency modulation through adjusting geometric configuration. To reduce resonance of a mechanism, this paper investigates the natural frequency modulation of a kinematically redundant planar parallel robot. A double-threshold searching method is proposed for controlling the inverse kinematics solution and keeping the natural frequencies away from the excitation frequency. The effectiveness of modulating the natural frequencies is demonstrated by comparing it with a non-modulation method. The simulation results indicate that, in all directions, the responses are coupled, and every order should be taken into consideration during natural frequency modulation. Compared to the non-modulation method, the proposed method can reduce the resonance amplitude to a certain extent, and the effect of vibration suppression is remarkable.

Natural Frequencies of Clamped Orthotropic Rectangular Plates With Varying Thickness

1978 ◽  
Vol 45 (4) ◽  
pp. 871-876 ◽  
Author(s):  
T. Sakata
Keyword(s):  
Rectangular Plate ◽  
Natural Frequency ◽  
Characteristic Equation ◽  
Natural Frequencies ◽  
Flexural Rigidity ◽  
Rectangular Plates ◽  
Double Trigonometric Series ◽  
Direction Parallel ◽  
Orthotropic Rectangular Plate ◽  
Fundamental Natural Frequency

The characteristic equation of a clamped orthotropic rectangular plate with thickness varying in one direction parallel to the side is derived analytically by the use of the double trigonometric series. By using the fundamental natural frequency determined from the characteristic equation, a formula is obtained numerically for estimating the fundamental natural frequency of a clamped orthotropic rectangular plate with thickness varying linearly in one direction. The accuracy of the formula and the influence of the flexural rigidity D1 on the natural frequency are discussed.

scholarly journals Static and Dynamic Analysis of Vibro Fluidized Bed Dryer using Finite Element Method

2018 ◽  
Vol 73 ◽  
pp. 05029
Author(s):  
Yohana Eflita ◽  
Haryanto Ismoyo ◽  
Dwiputra Muhamad Adrian ◽  
Luqmanul H Yusuf
Keyword(s):  
Dynamic Analysis ◽  
Fluidized Bed ◽  
Natural Frequency ◽  
Maximum Stress ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Enzymatic Oxidation ◽  
Static And Dynamic Analysis ◽  
Fluidized Bed Dryer ◽  
Working Principle

Vibro Fluidized bed dryer is a widely used tea dryer now. Its function is to stop the enzymatic oxidation process and decrease water content up to 2,8-3,8%. The working principle is to use the vibrations generated by the eccentric motor so that the tea powder that runs on the bed will vibrate. The purpose of this research is to model, static and dynamic of vibro fluidized bed dryer. The analysis was to determine the maximum stress and natural frequency of the vibro fluidized bed dryer to the variation of green tea mass being processed. Using dynamic analysis the obtained first three natural frequencies of the vibro fluidized bed dryer were 5,8876 Hz, 9,5267 Hz, and 10,512 Hz. The results showed that at 695 kg tea mass the natural frequency has the same as the excitation frequency. In this case, the safety factor of the vibro fluidized bed dryer is 27.6. It can be concluded that the maximum capacity of the vibro fluidized bed dryer is 695 kg..

Natural Frequency Analysis of Multilayer Truncated Conical Shells Containing Quiescent Fluid on Elastic Foundation with Different Boundary Conditions

2021 ◽  
Author(s):  
Reza Paknejad ◽  
Faramarz Ashenai Ghasemi ◽  
Keramat Malekzadeh Fard
Keyword(s):  
Boundary Conditions ◽  
Natural Frequency ◽  
Elastic Foundation ◽  
Conical Shell ◽  
Weight Functions ◽  
Conical Shells ◽  
Different Boundary Conditions ◽  
Fundamental Natural Frequency ◽  
Natural Frequency Analysis ◽  
Quiescent Fluid

In this paper, natural frequency of a multilayer truncated conical composite shell conveying quiescent fluid on elastic foundation with different boundary conditions is investigated and analyzed. The governing equations are presented based on the first-order shear deformation theory. Bernoulli’s equation and velocity potential have been used in the shell-fluid interface to obtain the fluid pressure. The fluid used in this study is considered non-compressible and non-viscous. The beam functions and the Galerkin weight functions method are used to describe and solve the coupled system of differential equations. Three types of boundary conditions are considered to investigate the natural frequency of the conical shells. The results show that the presence of the fluid in the conical shell reduces the fundamental natural frequency values. Also, by changing the semi-vertex conical angle from [Formula: see text] to [Formula: see text] for the simply support boundary conditions, the fundamental natural frequency value for the composite conical shell without and with fluid increases, and the presence of the elastic foundation increases the frequencies of the empty and full-fluid composite conical shells.

Nonlinear Resonances in a Flexible Cantilever Beam

1994 ◽  
Vol 116 (4) ◽  
pp. 480-484 ◽  
Author(s):  
T. J. Anderson ◽  
B. Balachandran ◽  
A. H. Nayfeh
Keyword(s):  
Natural Frequency ◽  
Cantilever Beam ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Continuous Systems ◽  
Modal Interactions ◽  
The Third ◽  
First Case ◽  
Second Mode ◽  
Band Limited

An experimental investigation into the response of a nonlinear continuous systems with many natural frequencies in the range of interest is presented. The system is a flexible cantilever beam whose first four natural frequencies are 0.65 Hz, 5.65 Hz, 16.19 Hz, and 31.91 Hz, respectively. The four natural frequencies correspond to the first four flexural modes. The fourth natural frequency is about fifty times the first natural frequency. Three cases were considered with this beam. For the first case, the beam was excited with a periodic base motion along its axis. The excitation frequency fe was near twice the third natural frequency f3, which for a uniform isotropic beam corresponds to approximately the fourth natural frequency f4. Thus the third mode was excited by a principal parametric resonance (i.e., fe ≈ 2f3) and the fourth mode was excited by an external resonance (i.e., fe ≈ f4) due to a slight curvature in the beam. Modal interactions were observed involving the first, third, and fourth modes. For the second case, the beam was excited with a band-limited random base motion transverse to the axis of the beam. The first and second modes were excited through nonlinear interactions. For the third case, the beam was excited with a base excitation along the axis of the beam at 138 Hz. The corresponding response was dominated by the second mode. The tools used to analyze the motions include Fourier spectra, Poincare´ sections, and dimension calculations.

Natural Frequency Based Topology Optimization of an Aircraft Engine Support Frame

2020 ◽  
Author(s):  
Braden T. Warwick ◽  
Chris K. Mechefske ◽  
Il Yong Kim
Keyword(s):  
Topology Optimization ◽  
Natural Frequency ◽  
Design Space ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Aircraft Engine ◽  
Problem Statement ◽  
Support Frame ◽  
Engine Excitation ◽  
Initial Geometry

Abstract The multi-stage design space refinement (MSDSR) technique increases the likelihood of convergence of topology optimization (TO) with large volume fraction constraints. This work considers MSDSR TO of an aircraft engine support frame with a natural frequency-based objective function. The problem statement maximized the first natural frequency, effectively maximizing the stiffness to mass ratio of the frame. The problem statement considered natural frequency constraints, which eliminated all natural frequencies within 5% of the engine excitation frequency times a safety factor of two. The design space did not consider the initial geometry; therefore, allowing for the determination of the optimal stiffener location on the initial geometry. The results of this work increased the first natural frequency of the engine support frame by 25.9%, eliminated all natural frequencies within 11.3% of the engine excitation frequency, and added only 0.253 kg of mass to the frame. The results of this work further demonstrate the advantages of MSDSR TO and the impact that it can have on the aerospace industry. Specifically, the design space considered in this work allows for the structural reinforcement of a pre-existing design, which is easier to implement and easier to regulate than similar results from the literature.

scholarly journals Free vibration analysis of isotopic rectangular plate with one edge free of support (CSCF and SCFC plate)

2014 ◽  
Vol 3 (1) ◽  
pp. 30 ◽  
Author(s):  
Stanley I Ebirim ◽  
J C Ezeh ◽  
M Owus Ibearugbulem
Keyword(s):  
Aspect Ratio ◽  
Free Vibration ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Shape Function ◽  
Ritz Method ◽  
Dimensional Parameter ◽  
Fundamental Natural Frequency ◽  
Aspect Ratios ◽  
Significant Difference

The paper presents a theoretical formulation based on Ibearugbulems shape function and application of Ritz method. In this study, the free vibration of simply supported plate with one free edge was analyzed. The Ibearugbulems shape function derived was substituted into the potential energy functional, which was minimized to obtain the fundamental natural frequency. Aspect ratios from 0.1 to 2.0 with 0.1 increments were considered. The values of fundamental natural frequencies of the first mode were determined for different aspect ratio. For aspect ratio of 1.0, the value of non-dimensional parameter of fundamental natural frequency obtained was 23.86. Comparison was made for values of non-dimensional parameter of fundamental natural frequencies obtained in this study with those of previous research works. It was seen that there is no significant difference between values obtained in this study with those of previous studies. Keywords: fundamental natural frequency; Ibearugbulems shape function; CSCF plate; Ritz method; SCFC plate.

scholarly journals On the natural frequencies of vibrating systems

1940 ◽  
Vol 174 (959) ◽  
pp. 433-457 ◽  
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Basic Problem ◽  
Exact Result ◽  
Exact Calculation ◽  
Normal Oscillation ◽  
Vibration Theory ◽  
Close Estimate ◽  
Different Parts ◽  
Vibrating Systems

The basic problem of Vibration Theory is to calculate for a given system the modes and associated frequencies of its “normal” free oscilla­tions. These are components into which the whole motion can be resolved when the system vibrates freely, and through small distances, about its position of equilibrium. Each one is wholly independent of every other, and has its own (in general) distinct phase and frequency, which are common to all parts of the system. Relatively to one another the amplitudes of different parts are invariant, but the phase and magnitude of a normal oscillation are not (in theory) restricted. Exact calculation is difficult even when attention is confined to the gravest (i. e. lowest) natural frequency, and on that account great value attaches to a theorem of Lord Rayleigh whereby a close estimate of this frequency can be based on a comparatively rough assumption in regard to the corresponding mode. It is known that the result will err, if at all, in the direction of over-estimation : if then by equally simple calculations it were possible to obtain a second figure close to it and known to be an under-estimate , such knowledge would for practical purposes be very nearly as useful as an exact result.

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