Vibration Characteristics Analysis of Aeroengine Composite Blade

2012 ◽  
Vol 583 ◽  
pp. 57-61
Author(s):  
Qiang Yang ◽  
Ke Qiang Fang ◽  
Chuang Shao
Keyword(s):  
Laser Scanning ◽  
Damping Ratio ◽  
Dynamic Test ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Modal Parameter ◽  
Blade Vibration ◽  
Nodal Lines ◽  
Composite Blade ◽  
Half Power

In order to validate the dynamic response and the dynamic stress distribution of the blade, EMA and FEM were performed to study the vibration characteristics. A non-contact laser scanning viberometer was used to measure the blade modal response. After the signal process of the response, the natural frequencies, mode shapes and their nodal lines can be obtained by the modal parameter identification method. And the blade modal damping ratio can be calculated from its frequency response function (FRF), which was obtained during the test, by the half-power method. Based on the test results, a simplified computational model was established by layup method, and after modification, the error of FEM results and EMA results was less than 5%. So the blade vibration characteristics and its finite element prediction model were obtained by the two methods combined, which would laid a foundation for the dynamic test and the vibration fatigue life prediction of the blade.

Experimental Study of Dynamic Test Characteristics on Nanjiang Road Bridge

2014 ◽  
Vol 501-504 ◽  
pp. 1378-1381
Author(s):  
Jia Mei Zhao ◽  
Bo Liu ◽  
Yu Liang Zhang
Keyword(s):  
Experimental Study ◽  
Natural Frequency ◽  
Dynamic Modulus ◽  
Damping Ratio ◽  
Dynamic Test ◽  
Vibration Characteristics ◽  
Test Characteristics ◽  
Crack Condition

Dynamic test has been carried out to completed road bridge of Nanjiang Port inTianjin. When cars were passing through the bridge, the dynamic deflections, the maximum amplitudes, the relation between amplitude and velocity, the Natural frequency and the damping ratio were gained. Dynamic modulus, vibration characteristics and crack condition of the bridge were determined so as to ascertain the reliability of the bridge.

Damping Identification and its Comparison for Various Types of Blade Couplings

2013 ◽  
Author(s):  
Zdenek Kubin ◽  
Vaclav Polreich ◽  
Vaclav Cerny ◽  
Petra Babkova ◽  
Lubos Prchlik
Keyword(s):  
Steam Turbine ◽  
Damping Ratio ◽  
Nonlinear Behavior ◽  
Mode Shapes ◽  
Material Damping ◽  
Blade Vibration ◽  
Friction Dampers ◽  
Linear Behavior ◽  
Disc Rotation ◽  
Identification Technique

Regarding steam turbine blade vibrations, damping of blade as well as bladed disc mode shapes is one of the most important parameters in terms of steam turbine operation. A value of the parameter depends on properties of material used for manufacturing and construction elements of the blades and the discs such as blade roots, shrouds, tiebosses (snubbers) and dampers. This article deals with a comparison of damping of mode shapes for particular blade couplings and shows which methods are suitable for determination of the damping in individual cases. The whole identification procedure of the damping together with its specifics is also presented. At first, an identification technique of material damping ratio is introduced and its results are given for different materials. The material damping ratio is assessed as material strain dependent. Subsequently, damping ratio of bladed disc mode shapes under bladed disc rotation is identified taking into account two alternatives. The alternatives differ in such a way that blades have been free for the first time and then coupled with friction dampers. Outcomes presented in the article illustrate good agreement between damping ratio of bladed disc mode shapes with free blades and material used for manufacturing of the blades. On the other hand, damping ratio of bladed disc mode shapes with friction dampers is significantly different and strongly dependent on blade vibration amplitudes as well as nodal diameters of bladed disc mode shapes. Finally, nonlinear behavior of the bladed disc has been revealed along large blade vibration amplitudes and higher nodal diameters of the disc. The non-linear behavior manifests itself in such a way that values of natural frequencies of the disc have become dependent on blade vibration amplitudes.

Dynamic Properties of MWNTS/Epoxy Nanocomposite Beams

2007 ◽  
Vol 334-335 ◽  
pp. 709-712 ◽  
Author(s):  
Meng Kao Yeh ◽  
Tsung Han Hsieh
Keyword(s):  
Dynamic Properties ◽  
Damping Ratio ◽  
Free Vibration Analysis ◽  
Mode Shapes ◽  
Laser Sensor ◽  
Vibration Source ◽  
Weight Percentage ◽  
Epoxy Nanocomposite ◽  
Fixed Base ◽  
Half Power

The dynamic properties of multi-walled carbon nanotubes (MWNTS)/epoxy nanocomposite beams were investigated experimentally and numerically. The MWNTs/epoxy nanocomposite beams were fabricated by hot press method. In experiment, the dynamic properties of the nanocomposite beams, such as natural frequency, and damping ratio, were obtained. A shaker was used to provide the vibration source at the fixed base of the specimens. The vibration signals of the nanocomposite beams were detected by a laser sensor, and the frequency responses were obtained by a computer-aided signal analyzer. The half power method was used to find the damping ratios of the nanocomposite beams for each mode. In analysis, the mechanical properties of MWNTs/epoxy nanocomposites were obtained and used in the free vibration analysis by the finite element method. The natural frequencies and mode shapes of the nanocomposite beams were calculated numerically. The effect of the weight percentage of MWNTs on the dynamic properties of the nanocomposite beams was investigated. The numerical results were found to be in good agreement with the experimental ones.

Study on Vibration Characteristics of Tires Related to Tire-Road Noise of Automobiles

2017 ◽  
Author(s):  
Akihiro Kawakami ◽  
Takashi Saito
Keyword(s):  
Error Function ◽  
Damping Ratio ◽  
Side Wall ◽  
Vibration Characteristics ◽  
The Other ◽  
Mode Shapes ◽  
Road Noise ◽  
Noise And Vibration ◽  
Modal Damping ◽  
The Impact

The occupants on board are being exposed to an environment in noise and vibration. Among them, the tire-road noise has come to relatively conspicuous because of improvement of silence. To improve comfort for occupants, reduction about the environmental noise and vibration is strongly expected. In this paper, we aim at knowing the vibration characteristics of tires related to tire-road noise of automobiles. Taking two kinds of tires, we carried out the impact tests. One has standard specification and the other has comfort specification absorbing vibration. Setting non-contact and contact to the ground, accelerances are obtained for single fixed input and multi output by impacting tests about tire treads and side-walls. To identify natural angular frequencies, modal damping ratios and modal amplitudes, the real and imaginary parts of accelerance are used in the error function of the optimized problem, which is solved by the down-hill simplex method. Both the natural angular frequencies and modes are identical for two kinds of tires each other. However, it is found that the modal damping ratio of the tire considered to be superior is not much different from the other. It is also found that when the tires contact with the ground, some natural frequencies could increase and other could decrease. Concerning about mode shapes, some axial mode shapes of tread might contradict with those of side-wall.

Modal Parameter Identification Method for Structural Health Monitoring Benchmark Model

2012 ◽  
Vol 594-597 ◽  
pp. 1113-1117
Author(s):  
Cheng Li ◽  
Ling Yu
Keyword(s):  
International Association ◽  
Damping Ratio ◽  
Combination Method ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Modal Parameter ◽  
Stochastic Subspace Identification ◽  
Identification Method ◽  
Modal Damping Ratio ◽  
American Society

Structural modal parameters can be identified using both output responses and input excitations or only using output responses of structures. When the input excitations are known, some frequency response functions (FRF) can be obtained and further used to accurately identify the modal frequencies and mode shapes of structures, but the identified modal damping ratio is often lack of reliability. Under ambient excitations, the peak picking method (PP) is often used to quickly identify the modal parameters of structures, but some vibration modes are missed sometimes, particularly when the dense modes or subjective errors may appear around the peaks picked. Modal parameters can be identified using the stochastic subspace identification method (SSI) based on statistical data, however, the SSI method easily produces false modes in practice. In order to compensate the deficiencies of SSI method, the PP and the SSI methods are combined to identify the modal parameters of the benchmark structure which proposed by the International Association for Structure Control and the task group of American Society Civil Engineers (IASC-ASCE) in this paper. The illustrated results show that this combination method can accurately identify the modal parameters of the benchmark structure with some application prospects.

Vibration Characteristics Analysis of a High-Speed Horizontal Machining Center

2012 ◽  
Vol 472-475 ◽  
pp. 849-852
Author(s):  
Jing Yang Nan ◽  
Min Wang ◽  
Tao Zan ◽  
Jin Xin Zhang
Keyword(s):  
High Speed ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Vertical Direction ◽  
Vibration Characteristics ◽  
Modal Testing ◽  
Mode Shapes ◽  
Vertical Column ◽  
Machining Center ◽  
Critical Components

By the experimental modal testing to the main structure of the high-speed horizontal machining center，the modal parameters such as the natural frequency, damping ratio, stiffness and mode shapes are obtained. By analyzing the vibration characteristics, the critical components of the machining center is at the spindle front bearing part and the vertical column on which the screw driving spindle box to move in vertical direction is mounted are determined, and provide an important basis of optimizing the structure for the machining center. And the amplitude-frequency characteristic curves of the critical components evaluate the dynamic stiffness as the key indicators to provide reliable data for improving processing accuracy and cutting ability of machining center.

An Eigensystem Realization Algorithm for Modal Parameter Identification of a Vertical-Shaft High-Speed Centrifugal Machine

2020 ◽  
Author(s):  
Sina Piramoon ◽  
Mohammad A. Ayoubi
Keyword(s):  
High Speed ◽  
Vibration Suppression ◽  
Damping Ratio ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Modal Parameter ◽  
Eigensystem Realization Algorithm ◽  
Minimum Order ◽  
Markov Parameters ◽  
Centrifugal Machine

Abstract In this paper, we utilize the observer/Kalman filter identification (OKID) and the eigensystem realization algorithm (ERA) techniques to identify the modal parameters of a centrifugal machine. To this end, we use an experimental setup to generate a pseudo-impulse input and collect output measurements which are corrupted by noise. We use the pseudo-impulse input and the OKID to find the Markov parameters of the system. Then we form the Hankel matrix of the system and determine the singular values of the system. A minimum-order, state-space model of the system is realized through the Markov parameters and then the natural frequency, damping ratio, mode shapes, and modal amplitudes at the sensor location are estimated by the ERA. We find three models for three separate cases and validate all the three identified models with the measured data and the Waterfall plot. The identified models are useful for designing passive or active vibration suppression control and fault detection systems. The results confirm that OKID/ERA is a reliable time-domain method for identifying the modal parameters of vertical centrifuge machines.

Composite Damping Circular Saw Blade Vibration Characteristics Analysis

2014 ◽  
Vol 670-671 ◽  
pp. 1106-1111 ◽  
Author(s):  
Ming Song Zhang ◽  
Pu Xian Zhu ◽  
Lian Bing Cheng
Keyword(s):  
Natural Frequency ◽  
Damping Ratio ◽  
Vibration Characteristics ◽  
Good Effect ◽  
Maximum Displacement ◽  
Blade Vibration ◽  
Circular Saw ◽  
Modal Damping Ratio ◽  
Circular Saw Blade ◽  
Saw Blade

Applying the method of finite element to research the composite damping vibration reduction effect of circular saw blade. Based on the structure of composite damping circular saw blade, contrast a composite saw blade and ordinary saw blade, to design and compare their vibration characteristics. Through research the vibration characteristics on the three kinds of saw blades found that the each order natural frequency of composite damping saw blade and composite saw blade is smaller than the corresponding order natural frequency of ordinary saw blade, and the each order natural frequency of composite damping saw blade slightly smaller than the corresponding order natural frequency of composite saw blade; The maximum displacement deformation of composite damping saw blade and composite saw blade is smaller than the corresponding order of ordinary saw blade. Through study the damping characteristics found that the modal damping ratio of composite damping saw blade is greater than others; and research the dynamics characteristics found that composite damping blade's vibration attenuation faster than others, and it illustrate the good effect of damping saw blade.

Vibration-based delamination evaluation in GFRP composite beams using ANN

2021 ◽  
pp. 096739112110033
Author(s):  
TG Sreekanth ◽  
M Senthilkumar ◽  
S Manikanta Reddy
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Composite Structures ◽  
Composite Beams ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Aviation Industry ◽  
Frequency Data ◽  
Fiber Reinforced ◽  
Back Propagation Algorithm

Delamination is definitely an important topic in the area of composite structures as it progressively worsens the mechanical performance of fiber-reinforced polymer composite structures in its service period. The detection and severity analysis of delaminations in engineering areas like the aviation industry is vital for safety and economic considerations. The existence of delaminations varies the vibration characteristics such as natural frequencies, mode shapes, etc. of composites and hence this indication can be effectively used for locating and quantifying the delaminations. The changes in vibration characteristics are considered as inputs for the inverse problem to determine the location and size of delaminations. In this paper Artificial Neural Network (ANN) is used for delamination evaluationof glass fiber-reinforced composite beams using natural frequency as typical vibration parameter. The Finite Element Analysis is used for generating the required dataset for ANN. The frequency-based delamination prediction technique is validated by finite element models and experimental modal analysis. The results indicate that the ANN-based back propagation algorithm can predict the location and size of delaminations in composites with good accuracy for numerical natural frequency data but the accuracy is comparitivelyless for experimental natural frequency data.

Research on Damping Properties of TiN Coating Prepared with Arc Ion Plating

2012 ◽  
Vol 184-185 ◽  
pp. 1167-1170
Author(s):  
Guang Yu Du ◽  
Zhen Tan ◽  
Kun Liu ◽  
Hao Chai ◽  
De Chun Ba
Keyword(s):  
Chemical Composition ◽  
Surface Morphology ◽  
Loss Factor ◽  
Steel Substrate ◽  
Damping Ratio ◽  
Energy Dispersive Spectrometer ◽  
Tin Coating ◽  
Arc Ion Plating ◽  
Ion Plating ◽  
Half Power

In this paper TiN coating was prepared on stainless steel substrate using arc ion plating technique. The coating samples’ phases, surface morphology, micro-determination chemical composition, loss factor and damping ratio were tested. The phases of TiN coating were determined by X-ray diffraction (XRD) technique. The surface morphology and chemical composition of the TiN coating were analyzed by scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS), respectively. The damping performance of the samples was measured by hammering activation according half power bandwidth method. The loss factor or damping ratio of samples were obtained according frequency response curve. The results showed that damping performance of samples was considerably improved by TiN coatings.

Sign in / Sign up

Export Citation Format

Share Document