scholarly journals Optimization of an EMU train carbody by the value of the natural bending frequency

2021 ◽  
Vol 80 (3) ◽  
pp. 152-159
Author(s):  
R. V. Guchinsky
Keyword(s):  
Vibration Frequency ◽  
Natural Vibration ◽  
The Body ◽  
Rolling Stock ◽  
Natural Vibration Frequency ◽  
Body Structure ◽  
Main Bearing ◽  
Bending Vibrations ◽  
Load Bearing ◽  
Target Values

Finding ways to optimize the body structure is an important point in the design of new electric train cars. Reducing the mass of the body leads to a lightening of the parts of the rolling stock associated with it, a reduction in energy consumption for operation and a decrease in wear in the “wheel — rail”system. Reducing the weight of the body is possible by assigning optimal rigidity to its main load-bearing elements. Increasing the rigidity of the body with a constant mass is also an important task to obtain the standard dynamic properties of the car body.The article presents method for optimizing the body structure based on calculating the value of its first frequency of natural bending vibrations. The calculation was carried out by the finite element method using a simplified beam-shell parametric model. Within the optimization calculations, 3125 working versions of sections of the main load-bearing structural elements with different rigidity were considered — bracing and cross-beams of the frame, inter-window racks and cross-beams of the roof. The sensitivity of the value of the natural vibration frequency to the change in the rigidity of the main bearing elements without taking into account the change in mass is analyzed. It was found that the rigidity of the frame bracing and cross beams has the greatest influence on the frequency value. It is shown that the ratio of the rigidity of the main bearing elements does not remain constant for optimal design options and depends on the design of the body, the target values of its mass and rigidity. When mass is limited, it is possible to choose designs that are characterized by the greatest overall body rigidity and are the most optimal in terms of manufacturability. By limiting the values of natural vibration frequency, it is possible to choose a body structure with the lowest metal mass. The presented approach allows making decisions on body modification based on the required parameters of mass and (or) the frequency of natural bending vibrations. This approach can be used in pre-design studies of the bodies of new passenger rolling stock.

scholarly journals Application of Elastic Fastenings of Equipment to Increase Vibration Frequency of the Wagon Body

2021 ◽  
Vol 19 (2) ◽  
pp. 6-12
Author(s):  
R. V. Guchinsky
Keyword(s):  
Vibration Frequency ◽  
Dynamic Performance ◽  
Relative Weight ◽  
The Body ◽  
Rolling Stock ◽  
Relative Mass ◽  
Natural Vibration Frequency ◽  
Bending Vibrations ◽  
Bending Vibration ◽  
Elastic Supports

Improving dynamic performance is a priority when designing new rolling stock. The frequency of natural bending vibrations of the body is one of the most important standardised indicators, a preliminary assessment of which allows obtaining optimal body designs.The objective of the work is to assess the prospects for the use of elastic fastenings of equipment to increase the natural vibration frequency of wagon bodies of suburban electric trains. Calculations were based on the finite element method and block Lanczos method. It is shown that it is advisable to use the rigid area tool and linearly elastic finite elements to calculate the frequencies in the simulation. The main ranges of fastening stiffness are highlighted, where the effect of using elastic supports is different. It is proposed to determine the stiffness of fastenings according to a given vibration frequency of the equipment. When the equipment is rigidly attached, the relative mass of the equipment does not affect the body bending vibration frequency. With elastic fastening, a greater effect can be achieved with a larger relative weight of the equipment. The effect of using resilient mounts increases with heavier equipment located closer to the centre of the body.It is shown that the effect of shear admittance of fastenings on the body vibration frequency is within 1 % and may not be considered in the simulation. In the considered example of a wagon body of a suburban electric train, the use of elastic supports allows an increase in the frequency of oscillations of the body by 3–10 %. 

Study on the Influence of Reactor Core Structure on Reactor Natural Vibration Frequency

2021 ◽  
Author(s):  
Yuan Zhou ◽  
Tian Tian ◽  
Xiongfei Yu ◽  
Ran Ren ◽  
Liangcai Zhou ◽  
...  
Keyword(s):  
Vibration Frequency ◽  
Natural Vibration ◽  
Reactor Core ◽  
Core Structure ◽  
Natural Vibration Frequency

scholarly journals Analysis of the natural oscillation frequency of the long-span trusses with flanged connections

2021 ◽  
pp. 76-85
Author(s):  
Татьяна Георгиевна Рытова ◽  
Людмила Анатольевна Максимова ◽  
Анастасия Георгиевна Николаева ◽  
Татьяна Михайловна Макарова ◽  
Надежда Георгиевна Пфаненштиль
Keyword(s):  
Dynamic Characteristics ◽  
Vibration Frequency ◽  
Natural Vibration ◽  
Natural Oscillation ◽  
Natural Vibration Frequency ◽  
Building Structures ◽  
Long Span ◽  
Local Areas ◽  
Calculation Results ◽  
Natural Oscillation Frequency

Приводится анализ частоты собственных колебаний большепролетной фермы с фланцевыми соединениями. Выполнен расчет фланцевого соединения с различными случаями исключения болтов из работы соединения. Анализ результата расчета показал, что возникновение повреждений и дефектов конструкций здания в локальных зонах, величина которых несущественно снижает общую жесткость каркаса, практически не влияет на динамические характеристики каркаса. The analysis of the natural vibration frequency of a large-span truss with flanged connections is given. The calculation of the flange connection with various cases of exclusion of bolts from the connection operation is performed. Analysis of the calculation results showed that the occurrence of damage and defects in the building structures in local areas, the value of which significantly reduces the overall rigidity of the frame, practically does not affect the dynamic characteristics of the frame.

An Experimental Investigation on Cylinder VIV Trajectories Under Different Model Scale

2014 ◽  
Author(s):  
Zh. Kang ◽  
Yunhe Zhai ◽  
Ruxin Song ◽  
Liping Sun
Keyword(s):  
Experimental Investigation ◽  
Vibration Frequency ◽  
Degrees Of Freedom ◽  
Natural Vibration ◽  
Cross Flow ◽  
Small Scale ◽  
Natural Vibration Frequency ◽  
Test Results ◽  
The Cross ◽  
Initial Research

In this paper, model tests were carried out to investigate two degrees of freedom VIV of horizontally-laid cylinders with diameters of 5cm, 11cm, 20cm and length 120cm and compared their vibration trajectories. The test results showed that the in-line and cross-flow vibration frequency of different scale cylinders demonstrate “multi frequency” phenomenon, that is, the in-line vibration frequency is not only twice but also once or four times as much as the cross-flow vibration frequency in some scale, natural frequency and reduced velocity conditions. Also, the cross-flow multi-frequency vibration phenomenon occurred. The trajectory of the vibration cylinder differentiated from the traditional “8” shape accordingly. The vibration trajectory, especially of small-scale cylinder, changed in most conspicuous manner. Through the initial research and analysis, it was found that in addition to in-line and cross-flow natural vibration frequency and the flow velocity, the shape of cylinders was also one of the main causes leading to different vibration trajectory forms.

Active Stiffening of Composite Materials by Embedded Shape-Memory-Alloy Fibres

1996 ◽  
Vol 459 ◽  
Author(s):  
J.-E. Bidaux ◽  
J.-A. E. Månson ◽  
R. Gotthardt
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Vibration Frequency ◽  
Composite Beam ◽  
Natural Vibration ◽  
Transformation Strain ◽  
Natural Vibration Frequency ◽  
The Matrix ◽  
Clamping Device ◽  
Composite Response

ABSTRACTThe use of shape-memory-alloy (SMA) fibres to actively changethe stiffness of a composite beam is investigated on a model system composed of an epoxy matrix with a series of embedded pre-strained NiTi fibres. Stiffness changes are detected through shifts in the natural vibration frequency of the beam. When electrically heated, the pre-strained NiTi fibres undergo a phase transformation. Since the shape recovery associated with the transformation is restrained by the constraints of both the matrix and the clamping device, a force is generated. This force leads to an increase in the natural vibration frequency of the composite beam. Depending on the degree of fibre pre-strain, either ordinary martensite, R-phase or a mixture of the two can be stress-induced. It is found that the R-phase gives rise to the largest change in vibration frequency for a given temperature increase and the most reversible behaviour. Its low transformation strain is also more favourable for fibre-matrix adhesion. The effect of stress relaxation in the polymer matrix on the composite response is discussed.

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