scholarly journals Study on the Natural Frequency Characteristics of Lift Gate Vibration Based on Added Mass Model

2016 ◽  
Author(s):  
Shihua He ◽  
Jianjun Zhu ◽  
Chunying Shen ◽  
Tingting Yang
Keyword(s):  
Natural Frequency ◽  
Added Mass ◽  
Frequency Characteristics ◽  
Mass Model

Natural Frequencies of a Railroad Track

1987 ◽  
Vol 54 (2) ◽  
pp. 299-304 ◽  
Author(s):  
S. P. Patil
Keyword(s):  
Natural Frequency ◽  
Elastic Layer ◽  
Natural Frequencies ◽  
Unit Length ◽  
Added Mass ◽  
Winkler Foundation ◽  
Railroad Track

The natural frequency of an infinite railroad track was first determined by Timoshenko as ωR = √k/m, where k is the constant for the massless Winkler foundation and m is the mass per unit length of the rail. The natural frequencies of the track are determined here by modeling the track as a beam resting on a 3-D inertial elastic layer. It is shown that the mass of the supporting foundation has a significant effect on the natural frequencies of a railroad track. Finally, the concept of “added mass” is introduced in order to determine the natural frequency in a desired mode of vibration, by modeling the track as a beam on the massless Winkler foundation and adding the mass of the foundation to the beam.

Frequency Characteristics Analysis of Micro-Displacement Structure with Parallel Flexure Hinges

2016 ◽  
Vol 693 ◽  
pp. 141-145
Author(s):  
Jie Qiong Lin ◽  
Ming Ming Lu ◽  
Xiao Qin Zhou ◽  
Qiang Liu
Keyword(s):  
Natural Frequency ◽  
Structure Design ◽  
Frequency Characteristics ◽  
Test Results ◽  
Structure Parameter ◽  
Dynamics Modeling ◽  
Displacement Structure ◽  
Flexure Hinges ◽  
Modeling Analysis ◽  
Characteristics Analysis

Flexure hinges based micro-displacement structure has been widely used for micro-precision machinery, and the natural frequency characteristics analysis is one of the most important elements in the structure design. In this paper, natural frequency characteristics analysis of a micro-displacement structure with parallel flexible hinges is presented. The effects of each structure parameter to the natural frequency of the micro-displacement structure are simulation by dynamics modeling. The parameters can be divided into three categories, namely, parallel flexure hinges parameter, micro-displacement structure parameter and material parameter. Two micro-displacement structures using common materials are machined for frequency test. The test results of two micro-displacement structure verified the modeling analysis, and the natural frequency characteristics analysis in this paper can be referenced in micro-displacement structure design.

Added-Mass Effect in Modeling of Cilia-Based Devices for Microfluidic Systems

2010 ◽  
Author(s):  
J. Kongthon ◽  
B. McKay ◽  
D. Iamratanakul ◽  
K. Oh ◽  
J.-H. Chung ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Vibration Amplitude ◽  
Vibrational Frequency ◽  
Substantial Reduction ◽  
Mass Effect ◽  
Added Mass ◽  
Hydrodynamic Drag ◽  
Vibrational Dynamics ◽  
Structure Interaction ◽  
Inertial Loading

This article shows that the added mass due to fluid structure interaction significantly affects the vibrational dynamics of cilia-based devices. Our main contribution is to show that such damping effects cannot explain the substantial reduction in the resonant vibrational frequency of the cilia operating in liquid when compared to the natural frequency of the cilia in air. It is shown that an added-mass approach (that accounts for the inertial loading of the fluid) can explain this reduction in the resonant vibrational frequency when operating the cantilever-type devices in liquids. Additionally, it is shown that the added-mass effect can explain why the cilia-vibration amplitude is not substantially reduced in a liquid by the hydrodynamic drag force. Thus, this article shows the need to model the added-mass effect, both, theoretically and by using experimental results.

scholarly journals Added-Mass Based Efficient Fluid–Structure Interaction Model for Dynamics of Axially Moving Panels with Thermal Expansion

2020 ◽  
Vol 25 (1) ◽  
pp. 9
Author(s):  
Nikolay Banichuk ◽  
Svetlana Ivanova ◽  
Evgeny Makeev ◽  
Juha Jeronen ◽  
Tero Tuovinen
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Galerkin Method ◽  
Fluid Structure Interaction ◽  
Weak Form ◽  
Added Mass ◽  
Mass Model ◽  
Partial Differential ◽  
Fluid Structure ◽  
Structure Interaction

The paper considers the analysis of a traveling panel, submerged in axially flowing fluid. In order to accurately model the dynamics and stability of a lightweight moving material, the interaction between the material and the surrounding air must be taken into account. The lightweight material leads to the inertial contribution of the surrounding air to the acceleration of the panel becoming significant. This formulation is novel and the case complements our previous studies on the field. The approach described in this paper allows for an efficient semi-analytical solution, where the reaction pressure of the fluid flow is analytically represented by an added-mass model in terms of the panel displacement. Then, the panel displacement, accounting also for the fluid–structure interaction, is analyzed with the help of the weak form of the governing partial differential equation, using a Galerkin method. In the first part of this paper, we represent the traveling panel by a single partial differential equation in weak form, using an added-mass approximation of the exact fluid reaction. In the second part, we apply a Galerkin method for dynamic stability analysis of the panel, and present an analytical investigation of static stability loss (divergence, buckling) based on the added-mass model.

Asynchronous Vibration Response Characteristics of Aero-Engine With Support Looseness Fault

2015 ◽  
Vol 11 (3) ◽  
Author(s):  
H. F. Wang ◽  
G. Chen ◽  
P. P. Song
Keyword(s):  
Numerical Integration ◽  
Natural Frequency ◽  
Rotational Speed ◽  
Frequency Multiplication ◽  
Lumped Mass ◽  
Mass Model ◽  
Response Characteristics ◽  
Aero Engine ◽  
Lumped Mass Model ◽  
Numerical Integration Methods

In this paper, the mechanism of the asynchronous vibration response phenomenon caused by the looseness fault in the aero-engine whole vibration system is investigated by numerical integration methods. A single degree-of-freedom (DOF) lumped mass model and a rotor-casing whole vibration model of a real engine are established, and two looseness fault models are introduced. The response of these two systems is obtained by numerical integration methods, and the asynchronous response characteristics are analyzed. By comparing the response of a single DOF lumped mass model with the response of multiple DOF model, the reason leading to the asynchronous response characteristics is the relationship between the changing period of stiffness and the changing period of the rotational speed. When the changing period of stiffness is equivalent to the changing period of the rotational speed, frequency multiplication will appear and the natural frequency will be excited at specific speeds. When the changing period of stiffness is equivalent to n (n = 2, 3,…) times the changing period of the rotating speed, 1/n (n = 2, 3,…) frequency division and frequency multiplication will appear and the natural frequency will be excited at specific speeds.

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