scholarly journals Vibration Analysis and Parameter Optimization of the Longitudinal Axial Flow Threshing Cylinder

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 571
Author(s):  
Jinwu Wang ◽  
Changsu Xu ◽  
Yanan Xu ◽  
Xin Qi ◽  
Ziming Liu ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Lightweight Design ◽  
Excitation Frequency ◽  
Axial Flow ◽  
Rotation Frequency ◽  
Vibration Characteristics ◽  
Inertia Force ◽  
Rotational Inertia ◽  
Maximum Deformation ◽  
Frequency Maximum

The longitudinal axial flow threshing cylinder of the full feeding rice combine harvester is widely used in China and works with violent vibration. To explore the source of the excitation affecting the vibration and to reduce the vibration, a finite element modal analysis and multipoint input and multipoint output (MIMO) modal test were performed to solve the natural vibration characteristics. By analyzing the excitation frequency, we concluded that the main reason for the resonance was the coupling between the rotation frequency of the threshing cylinder and the first natural frequency. To avoid the influence of resonance and realize a lightweight design, we proposed a combination of size optimization and topology optimization. The second rotation orthogonal combination test was designed to analyze the first natural frequency, maximum stress, and maximum deformation of the threshing cylinder, and the threshing cylinder was reconstructed as a central symmetrical structure to balance the rotational inertia force. The field experiment results showed that the amplitudes of the optimized threshing cylinder were significantly lower than those of the original threshing cylinder. This study provides ideas for solving the vibration characteristics of rotating parts and provides an important reference for the design of vibration reduction and weight reduction of key parts in the field of agricultural machinery.

scholarly journals Inertial Vibration Characteristics of Track Chassis Caused by Reciprocating Motion of Crank Slider

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Zhong Tang ◽  
Yu Li ◽  
Yuepeng Zhou ◽  
Haotian Zhang
Keyword(s):  
Excitation Frequency ◽  
Vertical Vibration ◽  
Vibration Characteristics ◽  
The Self ◽  
Force Balance ◽  
Inertia Force ◽  
Natural Mode ◽  
Reciprocating Motion ◽  
Measuring Point ◽  
Track Beam

The crank slider of self-propelled baling machinery is used for straw compression on the crawler chassis structure. During the reciprocating motion of the crank slider, the inertia of the piston will cause a greater shock to baling machinery. In this paper, the inertia of the crank slider piston was analyzed on crawler chassis. The model and parameter values of the inertia force balance of the crank slider were established by the complete balance method. The test mode was used to analyze the natural mode and mode shape of the piston. The vertical vibration amplitudes of the crawler chassis beam were tested and used to reflect the specific inertial vibration characteristics of the self-propelled baling machinery caused by the reciprocating motion of the piston. The inertial vibration caused by the reciprocating motion of the crank slider was eliminated by the method of weighting the tail of the track beam. Results indicated that the self-balancing counterweight of the crank slider was 261.82 kg. The six natural modal frequencies of the piston were 4.62, 17.26, 29.82, 63.85, 83.73, and 141.58 Hz, respectively. During the reciprocating motion of the piston, the first-order frequency of the piston would be excited by feeding auger excitation frequency of 3.77 Hz and may cause resonance. And, the vertical vibrates of track beam was based on the measuring point 6 as a fulcrum. Adding a counterweight of 265 kg at the end of the track chassis would completely eliminate the self-propelled baling machinery inertial vibration caused by the reciprocating motion of the crank slider.

Vibration characteristics analysis and structure optimization of air-pressure subsoiler

2021 ◽  
pp. 095745652110526
Author(s):  
Hongjie Su ◽  
Hongmei Cui ◽  
Feiyu Li ◽  
Chaolun Yideer ◽  
Yaxiong Zhu ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Structural Reliability ◽  
Excitation Frequency ◽  
Structure Optimization ◽  
Time Domain Analysis ◽  
Vibration Characteristics ◽  
Air Pressure ◽  
Excitation Source ◽  
External Excitation ◽  
Actual Production

Aiming at the problems of strong vibration, inconsistent subsoiling depth and high failure rate of air-pressure subsoiler, air-pressure subsoiler vibration characteristics was studied. In order to decrease the vibration, For the first time, the vibration characteristics of air-pressure subsoiler were obtained by modal analysis and vibration test. The vibration characteristics of the whole air-blown subsoiler are analyzed Through time domain analysis, it is found that the vibration acceleration of four deep loosening shovel is inconsistent. When the diesel engine is started, it is easy to cause inconsistent subsoiler depth. Then, by analyzing the vibration characteristics of the whole air-pressure subsoiler, it can be known that the external excitation source of the air-blown subsoiler is close to its own natural frequency. In order to avoid resonance caused by the vibration frequency of the external excitation source being close to the natural frequency of the air-pressure subsoiler, and to reduce the inconsistency of the subsoil depth, we optimize the design of air-pressure subsoiler. Instead of diesel engines, the steering gear box is connected with tractor power output shaft to provide power. The modal simulation of the optimized air-pressure subsoiler shows that the first-order natural frequency is obviously improved and the external excitation frequency is successfully avoided. It not only avoids resonance, reduces the damage of resonance components, but improves the service life of the subsoiler, greatly improves the structural reliability of the air-pressure subsoiler, at the same time, removes the main external excitation source, which greatly reduces the vibration in actual production and the inconsistency of subsoiling, which is of great significance in actual production. It provides a reference for the research of vibration characteristics, resonance avoidance and structure optimization of agricultural equipment.

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.

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.

Vibration Characteristics of Rotating Thin Disks—Part I: Experimental Results

2012 ◽  
Vol 79 (4) ◽  
Author(s):  
Ramin M. H. Khorasany ◽  
Stanley G. Hutton
Keyword(s):  
Frequency Response ◽  
Natural Frequency ◽  
Linear Theory ◽  
Lateral Force ◽  
Vibration Characteristics ◽  
Experimental Results ◽  
Rotating Disks ◽  
Critical Speeds ◽  
Applied Forces ◽  
Thin Disks

Analysis of the linear vibration characteristics of unconstrained rotating isotropic thin disks leads to the important concept of “critical speeds.” These critical rotational speeds are of interest because they correspond to the situation where a natural frequency of the rotating disk, as measured by a stationary observer, is zero. Such speeds correspond physically to the speeds at which a traveling circumferential wave, of shape corresponding to the mode shape of the natural frequency being considered, travel around the disk in the absence of applied forces. At such speeds, according to linear theory, the blade may respond as a space fixed stationary wave and an applied space fixed dc force may induce a resonant condition in the disk response. Thus, in general, linear theory predicts that for rotating disks, with low levels of damping, large responses may be encountered in the region of the critical speeds due to the application of constant space fixed forces. However, large response invalidates the predictions of linear theory which has neglected the nonlinear stiffness produced by the effect of in-plane forces induced by large displacements. In the present paper, experimental studies were conducted in order to measure the frequency response characteristics of rotating disks both in an idling mode as well as when subjected to a space fixed lateral force. The applied lateral force (produced by an air jet) was such as to produce displacements large enough that non linear geometric effects were important in determining the disk frequencies. Experiments were conducted on thin annular disks of different thickness with the inner radius clamped to the driving arbor and the outer radius free. The results of these experiments are presented with an emphasis on recording the effects of geometric nonlinearities on lateral frequency response. In a companion paper (Khorasany and Hutton, 2010, “Vibration Characteristics of Rotating Thin Disks—Part II: Analytical Predictions,” ASME J. Mech., 79(4), p. 041007), analytical predictions of such disk behavior are presented and compared with the experimental results obtained in this study. The experimental results show that in the case where significant disk displacements are induced by a lateral force, the frequency characteristics are significantly influenced by the magnitude of forced displacements.

Sheet Material Property Effects upon Dynamic Behavior in Self-Pierce Riveted Joints

2011 ◽  
Vol 675-677 ◽  
pp. 999-1002 ◽  
Author(s):  
Xiao Cong He
Keyword(s):  
Natural Frequency ◽  
Transverse Vibration ◽  
Spot Welding ◽  
Sheet Material ◽  
Vibration Characteristics ◽  
Efficient Design ◽  
Material Density ◽  
Sheet Materials ◽  
Riveted Joints ◽  
Free Transverse Vibration

Self-pierce riveting (SPR) technology offers an alternative to resistance spot welding (RSW) for joining sheet materials. It has been found that the SPR technology produced a much stronger joint than the RSW in fatigue test. For efficient design of SPR structures, the knowledge of dynamic characteristics of the SPR beams is essential. In this paper, the free transverse vibration characteristics of single lap-jointed cantilevered SPR beams are investigated in detail. The focus of the analysis is to reveal the influence on the natural frequency and natural frequency ratio of these beams caused by variations in the material properties of sheet materials to be jointed. It is shown that the transverse natural frequencies of single lap jointed cantilevered SPR beams increase significantly as the Young’s modulus of the sheet materials increases, but change slightly corresponding to the change in Poisson’s ratio. It is also found that the material density of the sheets have significant effects on the free transverse vibration characteristics of the beams.

Investigation on a Type of Flow Control to Weaken Unsteady Separated Flows by Unsteady Excitation in Axial Flow Compressors

2004 ◽  
Author(s):  
Xin-Qian Zheng ◽  
Xiao-Bo Zhou ◽  
Sheng Zhou
Keyword(s):  
Wide Spectrum ◽  
Excitation Frequency ◽  
Axial Flow ◽  
Maximum Velocity ◽  
Excitation Amplitude ◽  
High Order Scheme ◽  
Wide Range ◽  
Optimal Excitation ◽  
Suction And Blowing ◽  
Axial Flow Compressors

By solving unsteady Reynolds-averaged 2-D N-S equations discretized by a high-order scheme, the results showed that the disordered unsteady separated flow could be effectively controlled by periodic suction and blowing in a wide range of incidence, resulting in enhancement of time-averaged aerodynamic performances. The effects of unsteady excitation frequency, amplitude and excitation location were investigated in detail. The effective excitation frequency spans a wide spectrum and there is an optimal excitation frequency that is nearly equal to the Characteristic frequency of vortex shedding. Excitation amplitude exhibits a threshold value (nearly 10% in term of the ratio of maximum velocity of periodic suction and blowing to the velocity of free flow) and an optimal value (nearly 35%). The optimal excitation location is just upstream of the separation point. We also explored feasible unsteady actuators by utilizing upstream wake for constraining unsteady separation in axial flow compressors.

scholarly journals Vibrational Analysis on Hemp and Okra Fibres Mixed Glass Fiber Polyester Composite

2021 ◽  
Vol 8 (11) ◽  
pp. 55-62
Author(s):  
Putti Venkata Siva Teja ◽  
Badatala Ooha ◽  
Kondeti Sravanth
Keyword(s):  
Glass Fiber ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Fiber Composite ◽  
Fem Analysis ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Machine Component ◽  
Free System ◽  
Glass Fiber Composite

In transverse vibrations the element moves to and fro in a direction perpendicular to the direction of the advance of the wave. To determine the vibration characteristics i.e., natural frequencies and mode shapes, modal analysis is a process for a structure or a machine component while is being designed. In real life, aero planes, missiles, rockets, space vehicles, satellites, sub marines etc are modeled as free-free mechanical systems. In this paper an attempt was made to compare natural frequency for two composite materials- ladies finger with Glass fiber composite and Hemp with Glass fiber composite by taking as cantilever beams. The cantilever beam which is fixed at one end is vibrated to obtain the natural frequency, mode shapes at four different modes. A simple low cost demonstration experiment is performed in this paper by using common apparatus in order to compare theoretical, numerical (FEM analysis) profiles of two free-free thin two rectangular composite beams of dimensions 305*49.5* 7 in mm. Keywords: Natural frequencies, Mode shapes, Vibration characteristics, Ladies finger fiber, Hemp fiber, Glass fiber, FEM analysis, Free-Free system.

Dynamic Stress Prediction in Centrifugal Compressor Blades Using Fluid Structure Interaction

2012 ◽  
Author(s):  
Andrew H. Lerche ◽  
J. Jeffrey Moore ◽  
Nicholas M. White ◽  
James Hardin
Keyword(s):  
Computational Model ◽  
Centrifugal Compressor ◽  
Excitation Frequency ◽  
Axial Flow ◽  
Compressor Blades ◽  
Fluid Structure ◽  
Design Changes ◽  
Cause Of Failure ◽  
Stress Prediction ◽  
Blade Failure

A computational model is developed that predicts stresses in the blades of a centrifugal compressor. The blade vibrations are caused by the wakes coming off stationary inlet guide vanes upstream of the impeller, which create a periodic excitation on the impeller blades. When this excitation frequency matches the resonant frequency of the impeller blades, resonant vibration is experienced. This vibration leads to high cycle fatigue, which is a leading cause of blade failure in turbomachinery. Although much research has been performed on axial flow turbomachinery, little has been published for radial machines such as centrifugal compressors and radial inflow turbines. A time domain coupled fluid-structure computational model is developed. The model couples the codes unidirectionally, where pressures are transferred to the structural code during the transient solution, and the fluid mesh remains unaffected by the structural displacements. A Fourier analysis is performed of the resulting strains to predict both amplitude and frequency content. This modeling method was first applied to a compressor in a single stage centrifugal compressor test rig. The analysis results were then validated by experimental blade strain measurements from a rotating test. The model correlated very well with the experimental results. In this work, a model is developed for a liquefied natural gas (LNG) centrifugal compressor that experienced repeated blade failures. The model determined stress levels in the blades, which helped to predict the likely cause of failure. The method was also used to investigate design changes to improve the robustness of the impeller design.

Dynamic Analysis for Wind Turbine Composite Blade

2013 ◽  
Vol 364 ◽  
pp. 102-106 ◽  
Author(s):  
Li Qun Zhou ◽  
Shuai Heng Xing ◽  
Yu Ping Li
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Wind Turbine Blade ◽  
Inertia Force ◽  
Rotational Inertia ◽  
Fiber Layer ◽  
Composite Blade ◽  
Nature Frequency ◽  
The Relationship ◽  
Blade Model

Wind turbine blade model is analyzed based on finite element method. Research and comparison of blade natural frequencies is made in different rotational working conditions taking into account external factors such as the rotational inertia force. Also the relationship between the composite ply angle and natural frequency is analyzed. The result shows that the nature frequency of wind turbine blade is influence greatly by the stress stiffening effect for the blade rotation. And the nature frequency of wind turbine blade can be designed by adjusting the single fiber layer ply angle of blade.

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