scholarly journals Analysis and Research on Longitudinal Vibration Characteristics of Deep Sea Mining Pipe Based on Finite Element Method

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Qiang Liu ◽  
Linjing Xiao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Natural Frequency ◽  
Vibration Amplitude ◽  
Longitudinal Vibration ◽  
Excitation Frequency ◽  
Vibration Characteristics ◽  
Wind Condition ◽  
Vibration Intensity ◽  
Element Method

This paper aimed to study the longitudinal vibration characteristics of the 5000 m mining pipe in the ocean under different working wind conditions, offset angle, damping, and ore bin weight. Based on the finite element method, the mining pipe is simplified into beam element and discretized, and the physical and mathematical models of the mining pipe system are established. The Wilson-θ direct integral method is adopted for numerical calculation. The results show that the longitudinal vibration of the mining pipe is irregular, which presents the phenomenon of oscillation. The vibration amplitude decreases first and then increases from top to bottom, the minimum vibration amplitude appears at 1000 m, and the maximum vibration amplitude appears at the top of the mining pipe. Under the same working wind condition, the overall longitudinal vibration amplitude of the mining pipe can be increased by increasing the ore bin weight and the offset angle, but neither of them can change the frequency of the longitudinal vibration. The closer the excitation frequency generated by different working wind conditions is to the natural frequency, the larger the mining pipe longitudinal vibration amplitude is. The closer the vibration frequency generated by the same excitation frequency is to the natural frequency, the stronger the vibration intensity is, and when damping is added, the vibration intensity decreases faster.

Study of Snubbing Mechanism Using Finite Element Method

2014 ◽  
Author(s):  
Jingming Chen ◽  
Paolo Pennacchi ◽  
Dongxiang Jiang ◽  
Steven Chatterton
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Forced Vibration ◽  
Excitation Frequency ◽  
Relative Displacement ◽  
Rotor Blades ◽  
Motion Pattern ◽  
Motion Characteristics ◽  
The Time Domain ◽  
Element Method

In the rotating machineries, large vibrations of a blade would result in fatigue crack, which is a great threaten to the safety. Therefore, it is of great importance to reduce the blade vibrations. Snubbing technique is a possible solution to this problem. A tiny gap is left between the shrouds of adjacent blades. While the forced vibration makes the relative displacement between two neighboring blades exceed the gap, the contact happens at the contact face of the shrouds, accompanied with friction and energy dissipation, which restricts the vibration. In this paper, a simplified model for a set of rotor blades is established, by using finite element method. The contact between the adjacent shrouds is considered. In this way, snubbing phenomenon can occur under forced vibration. Based on the model, modal analysis has been conducted. The 8x rev. frequency has been chosen as the excitation frequency. Under a certain amplitude of sine excitation, the circumferential vibration of the blades has been simulated. The vibration has been analyzed in the time domain. As expected, the blade motion is divided into four different states in one period. They are: non-contact, rebounding, sticky and escaping state. The four states had different mechanical and motion characteristics. The motion pattern for the set of blades has been also analyzed and the wave spreading along the bladerow has been described. Because of the snubbing mechanism, the waveform was distorted into serrated shape.

Natural Frequencies of Rectangular Membrane With Boundary Perturbation

1995 ◽  
Vol 1 (2) ◽  
pp. 139-144 ◽  
Author(s):  
Jamal A. Masad
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Galerkin Method ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Perturbation Approach ◽  
Boundary Perturbation ◽  
The Finite Element Method ◽  
Analytic Expression ◽  
Element Method

A perturbation approach, coupled with the adjoint concept, is used to derive an analytic expression for the natural frequencies of a nearly rectangular membrane. The method is applied for a rectangular membrane with a semicircle at one of the boundaries. The fundamental natural frequency results for this configuration are presented and compared with results from a finite-element method and results from an approximate Galerkin method. The agreement between the fundamental natural frequencies calculated with the perturbation approach and those calculated with the finite-element method improves as the radius of the semicircle decreases and as the semicircle location becomes more eccentric.

Tolerance Induced Performance Variation of a High-Resolution Compliant Micro Stage

2007 ◽  
Author(s):  
Jhy-Cherng Tsai ◽  
Mandy Hsiao ◽  
Jau-Liang Chen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
High Resolution ◽  
Natural Frequency ◽  
Sensitivity Analyses ◽  
Compliant Structure ◽  
Nano Scale ◽  
Leaf Springs ◽  
Performance Variation ◽  
Element Method

Micro stage employs compliant structure is crucial for precision machinery as it can achieve nano-scale resolution fine displacement by deformation. This paper investigates the variations of stiffness and natural frequency due to dimensional tolerances of such a compliant micro stage that is suspended by four leaf springs and rotates with respect to hinges. Performances of the stage are evaluated by finite element method for various dimensions to investigate the effects of dimensions. A series of sensitivity analyses are also performed to investigate how tolerances affect the performance of the stage. It shows that the stiffness and natural frequency of the stage are strongly affected by the dimensions of leaf springs and the hinges. That is, tolerances of these dimensions are crucial and must be well designed and strictly controlled. It further shows that performance variation due to tolerances are nonlinear but can be properly designed with this approach.

Free Vibration Characteristics of Sandwich Conical Shells With FGM Face Sheets: A Finite Element Approach

2019 ◽  
Author(s):  
Tripuresh Deb Singha ◽  
Apurba Das ◽  
Gopal Agarwal ◽  
Tanmoy Bandyopadhyay ◽  
Amit Karmakar
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Free Vibration ◽  
Conical Shell ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Iteration Algorithm ◽  
Operational Life ◽  
Sandwich Type ◽  
Element Method

Abstract This paper presents an analytical investigation on the free vibration characteristics of symmetric sandwich conical shell with functionally graded material (FGM) face sheets using finite element method. Sandwich-type structures offer higher stiffness to weight ratio with excellent thermal barrier in high temperature application extending the operational life of the component. The sandwich-type conical structure used in the advanced supersonic and hypersonic space vehicles. The material properties of FGM face sheets are considered to be varied in thickness direction as per simple power law distribution in terms of the volume fractions of the FGM constituents. The core layer is considered as homogeneous and made of an isotropic material (Titanium alloy-Ti–6Al–4V). A finite element method is used to reduce the governing equations of vibration problem. The QR iteration algorithm used to solve the standard eigen value problem for determine the natural frequencies. Convergence studies are performed in respect of mesh sizes to substantiate the accuracy of the proposed method. Computer codes developed to obtain the numerical results for the combined effects of twist angle and rotational speed on the free vibration characteristics of symmetric sandwich conical shell with FGM face sheets. A detailed numerical study is carried out to examine the influence of the sandwich plate type, volume fraction index on the free vibration characteristics. The typical mode shapes are also illustrated for different cases.

Simulation and Analysis of Cantilever-Membrane Structure for Piezoresistive Micro-Accelerometers

2012 ◽  
Vol 503 ◽  
pp. 87-90 ◽  
Author(s):  
Yan Liu ◽  
Yu Long Zhao ◽  
Lu Sun
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Natural Frequency ◽  
Frequency Band ◽  
Membrane Structure ◽  
Measurement Sensitivity ◽  
First Order ◽  
Working Frequency ◽  
Element Method

Dynamic and static performances are the most important parameters for accelerometers. The natural frequency decides the sensor’s working frequency band, and the accompanying stress represents the measurement sensitivity. In this paper, a novel sensing structure, cantilever-membrane structure, for piezoresistive accelerometers is studied, in order to detect the structural dimension’s effect on the sensor. With the help of FEM (Finite element method) software, the first order natural frequency of the cantilever-membrane based accelerometer is investigated with the different combinations of membrane’s dimensions. The accompanying stress of the sensing structure is also simulated in this paper. The results show that the membrane’s dimensions affect the frequency and stress more tempestuously when the membrane is short, but the tendency become gentle when the width of the membrane increases.

The Vibration Characteristics Analysis of Ship Foundation Based on the Arrangement of Isolators

2011 ◽  
Vol 55-57 ◽  
pp. 2202-2205
Author(s):  
Yu Wang ◽  
Xing Lin Chen ◽  
Guang Min Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Natural Frequency ◽  
Vibration Characteristics ◽  
Force Characteristic ◽  
The Finite Element Method ◽  
Foundation Vibration ◽  
Characteristics Analysis ◽  
Excitation Force ◽  
General Connection

Contrary to the general connection style, the vibration characteristics of the ship foundation vibration is researched under the arrangement style of isolators acted on it. And the influence of the parameters of rigidity and damp to the excitation force characteristic is studied too. Based on the real ship data and the finite element method, the study is shown that the excitation force from the device to the foundation is not only related to the rigidity, damp of isolators and the natural frequency of device-isolator-foundation system but also the related to arrangement style of isolator. When the excited frequency is lower it had little effect on the vibration characteristics relatively. However that the frequency is higher, it had significant effect on the vibration.

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