scholarly journals Nonlinear Dynamic Performance of a Bolt-Disc Rotor with the Position Error of Circumferential Bolt-Holes

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Haibo Zhang ◽  
Yi Liu ◽  
Xin Huang
Keyword(s):  
Dynamic Properties ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Position Error ◽  
Dynamic Features ◽  
Three Dimensional Model ◽  
Tightening Force ◽  
Rotating Speed ◽  
Mass Eccentricity ◽  
Bolt Holes

The bolt-holes in the assembly discs are designed to limit the circumferential displacement of bolts for the bolt-disc rotor. The position error of circumferential bolt-holes is created in a three-dimensional model of bolt-disc rotor. The distribution of nonuniform stress and deformation is acquired according to finite element approach. Static results demonstrate that the position error of bolt-holes leads to obvious concomitant unbalances including constant mass eccentricity and speed-variant bending under the influence of large tightening force. When these unbalance factors are taken into consideration, dynamic performance such as instability areas and nonlinear motions are analyzed by Newton iterative process and a prediction-correction calculation method. Dynamic results show that rotor flexure enables the systematic stability decreased obviously because of this position error. There is a special phenomenon compared to monobloc rotor that the vibration amplitude proceeds to rise when rotating speed exceeds the critical speed. Moreover, the allowable position error of bolt-holes is obviously smaller than that of monobloc rotor and uneven tightening is a feasible way to reduce adverse effects on the dynamic properties when position error appears. This work proposes a static-dynamic approach to investigate the dynamics of imprecise bolt-disc rotor and establishes the relationship between machining error and dynamic features.

Theoretical Analysis and FEM Simulation of Piezoelectric Vibrator Used in Ultrasonic EDM System

2013 ◽  
Vol 694-697 ◽  
pp. 3020-3024
Author(s):  
Hong Bing Wang ◽  
Zhi Rong Li ◽  
Chun Hua Sun
Keyword(s):  
Theoretical Analysis ◽  
Natural Frequencies ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Fem Simulation ◽  
Model Analysis ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Piezoelectric Vibrator ◽  
Working Frequency

The dynamic performance of the piezoelectric vibrator used in ultrasonic EDM machine in natural frequencies has a great effect on machining precision. Firstly, Through theoretical analysis the dynamic characteristics of the piezoelectric vibrator is obtained. Then the three-dimensional model of the piezoelectric vibrator is constructed by using PRO/E software, and model analysis is carried by using FEM software. Through theoretical analysis and FEM simulation, the appropriate working frequency and mode of the piezoelectric vibrator was found, and the piezoelectric vibrator was fabricated. Experimented results show that the model analysis of frequency is accord with that of FEM.

The Research on Seismic Performance of Tower under Icing Condition

2014 ◽  
Vol 986-987 ◽  
pp. 677-680
Author(s):  
Yu Chen Tian ◽  
Wei Jian Xue ◽  
Ying Zhou ◽  
Lan Jiang
Keyword(s):  
Transmission Lines ◽  
Southwest China ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Seismic Action ◽  
The Finite Element Method ◽  
Three Dimensional Model ◽  
Deformation Law ◽  
Prone Area ◽  
Internal Forces

Southwest area of china is the zone of the transmission lines which often happens icing disaster. It is also an earthquake-prone area, also influenced by the interaction between ice and earthquake. This article uses the finite element method (fem), establishing three-dimensional model for steel towers in southwest china, to analyze the dynamic performance of the ice condition and the analysis of seismic action. The aim is to get internal forces for steel towers under the action of earthquake and deformation law along with the change of ice thickness.

The Radial Fretting Character Research of the Shaft-Hub of Compress Impeller Based on Virtual Orthogonal Experiment

2014 ◽  
Vol 668-669 ◽  
pp. 289-293
Author(s):  
Xue Long Lu ◽  
Jun Sheng Zhao ◽  
Xin Zhong Huang ◽  
Shuang Yong Wang
Keyword(s):  
Orthogonal Experiment ◽  
Orthogonal Design ◽  
Three Dimensional ◽  
Element Model ◽  
Optimization Method ◽  
Three Dimensional Model ◽  
Interference Fit ◽  
Rotating Speed ◽  
Compressor Impeller ◽  
Set Up

A three-dimensional model of as haft-hub of compressor impeller was set up by Pro/E. Based on the ANSYS; the finite element model was established, using the analysis method of combining submodle and paramesh. The shaft-hub of compressor impeller was simulated by virtual orthogonal design optimization method. Based on the fact that there existed radial fretting in the shaft-hub interference fit joint, researching the influence significance order and law of interference, friction coefficient and rotating speed to the maximum unit frictional work , the average friction work and the optimized parameter were obtained. It turned out that the results of the numerical simulation and orthogonal experiment were accurate and reliable, with the friction and wear effectively reduced, certain guiding references to actual assembly process were got.

Chaos Properties of a Rotor System With Nonlinear Hydro-Static Bearings

2007 ◽  
Author(s):  
Changping Chen ◽  
Liming Dai
Keyword(s):  
Nonlinear Dynamic ◽  
Dynamic Properties ◽  
Nonlinear Behavior ◽  
Design Parameters ◽  
Rotating System ◽  
Rotating Speed ◽  
Highly Nonlinear ◽  
Mass Eccentricity ◽  
Nonlinear Dynamic Properties ◽  
Parameter Values

General motions of discs and shafts of large rotary machines appear with highly nonlinear behavior. The geometries of the shafts and the supporting systems of this machine can all be treated as nonlinear. This paper aims to investigate the chaos properties of the nonlinear rotating system. The nonlinear dynamic governing equations of the rotating bearing system are derived. The geometric nonlinearity of the shaft, nonlinear hydrostatic forces of the bearings, mass of the shaft and disc, deformation of the shaft and a disc mounted on the shaft, and the viscoelasticity of the supports are all taken into account. Numerical simulations are performed in the research for studying the bifurcation and chaos properties of the specified nonlinear rotating system. The effects of the shaft’s rotating speed and the mass eccentricity of the disc on the nonlinear dynamic properties of the system are investigated in detail. The results show that abundant of bifurcations and chaos exist in this nonlinear rotating system Corresponding to certain parameter values. The bifurcations and chaotic phenomena should be avoided when designing the rotating system by adjusting the design parameters. The results of this research can hereby be used for guiding the design and operation of rotor-bearing systems.

ENERGY-BASED APPROACH TO ESTIMATE SEISMIC DEMANDS FOR ASYMMETRIC BUILDINGS

2010 ◽  
Vol 04 (03) ◽  
pp. 215-230 ◽  
Author(s):  
RAMIN TABATABAEI ◽  
HAMED SAFFARI
Keyword(s):  
Seismic Response ◽  
Dynamic Properties ◽  
Pushover Analysis ◽  
Three Dimensional ◽  
Lateral Force ◽  
Three Dimensional Model ◽  
Seismic Demands ◽  
Asymmetric Buildings ◽  
Plastic Mechanism ◽  
Response History Analysis

In this paper, an energy-based approach to estimate the inelastic response of buildings is presented. In order to estimate torsional effects on the seismic response of structure, the associated plastic mechanism is developed in the three-dimensional model using an adapted version of the DRAIN-3DX program. The changing dynamic properties due to plastic mechanism are used for the calculation of modal lateral loads. Thus, the effects of both stiffness changes and localized response mechanisms at the structure under modal loading are included. The total input energy due to seismic loading is composed of both work done by (1) lateral force pattern acting through the translation displacement and (2) torsion acting through the rotation of each floor. For assessment of the seismic response of asymmetric buildings, the proposed procedure is shown to provide superior results compared to those obtained through deployment of the other methods commonly used: the adaptive modal combination (AMC) procedure, the modal pushover analysis (MPA), and the response history analysis (RHA) approach.

The Dynamic Performance Research of Fixture for Automobile Hydraulic Vibration Reliability Test

2010 ◽  
Vol 37-38 ◽  
pp. 1452-1456
Author(s):  
Yi Shan Zeng
Keyword(s):  
Hydraulic System ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Great Influence ◽  
Reliability Test ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Vibration Reliability ◽  
Vibration Modal ◽  
Performance Research

In order to test the reliability of automobile hydraulic, the vibration reliability test needs to be done. The fixture, which is used to clamp and fix the hydraulic system, is one of the most important components of the test. So the dynamic performance of the fixture has great influence on the vibration test. According to the figure and setting localization of electronics, the three-dimensional model of fixture was constituted. The modal frequency and vibration modal were calculated using FEM. By the result of analysis, the structure of the fixture was mended to meet the test requirement.

Modal Analysis of Helical Milling Unit

2012 ◽  
Vol 482-484 ◽  
pp. 2454-2459 ◽  
Author(s):  
Xu Da Qin ◽  
Cui Lu ◽  
Qi Wang ◽  
Hao Li ◽  
Lin Jing Gui
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Element Model ◽  
Helical Milling ◽  
Mode Shapes ◽  
Three Dimensional Model ◽  
Working Principle ◽  
The Finite Element Model

Based on the analysis of the working principle and structure characteristics of helical milling unit, the prototype’s three-dimensional model was built, the prototype’s finite element modal analysis was conducted, and the first 6 natural frequencies and their mode shapes were obtained. The finite element model is experimentally validated by comparing finite element and experimental modal’s parameters. This paper investigates the dynamic properties of prototype, and provides theoretical references for the subsequent dynamic analysis and structural optimization.

Nonlinear dynamic properties of disk-bolt rotor with interfacial cutting faults on assembly surfaces

2017 ◽  
Vol 24 (19) ◽  
pp. 4369-4382
Author(s):  
Yi Liu ◽  
Heng Liu ◽  
BoWen Fan
Keyword(s):  
Nonlinear Dynamic ◽  
Dynamic Properties ◽  
Dynamic Balance ◽  
Three Dimensional ◽  
Rotor System ◽  
Contact Algorithm ◽  
Mass Eccentricity ◽  
Specific Shape ◽  
Nonlinear Dynamic Properties ◽  
Coupling Characteristics

Interfacial cutting faults on assembly surfaces are considered in a three-dimensional (3D) disk-bolt rotor system. The traditional finite element method is used to establish the 3D model of faulted disk-bolt rotor. A contact algorithm is applied to calculate the static features of this combined rotor. It is revealed that interfacial cutting faults produce rotor bending which is gradually strengthened as rotational speed increases besides disk’s mass eccentricity. The 3D dynamic equations of a faulted disk-bolt rotor system include these cutting faults’ static influences. The nonlinear dynamic properties are investigated by Poincaré mapping, Newton iteration and a prediction-correction algorithm. As a result, the rotor bending due to cutting faults reduces the global stability of the complicated rotor and enlarges the vibration amplitude obviously. This speed-variant bending also decides the feature that rotor vibration increases again after critical speed no matter whether dynamic balance is carried out. The maximum allowable fault depth is obtained and it gives an explanation as to why the machining precision of assembly surfaces should be strictly controlled in the disk-bolt rotor. Generally, this paper originally tries to provide a feasible approach to consider a 3D interfacial cutting fault with specific shape and to analyze the static–dynamic coupling characteristics for a disk-bolt rotor.

Nonlinear dynamic characteristics of a three-dimensional rod-fastening rotor bearing system

2014 ◽  
Vol 229 (5) ◽  
pp. 882-894 ◽  
Author(s):  
Yi Liu ◽  
Heng Liu ◽  
Xin Wang ◽  
Minqing Jing
Keyword(s):  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Three Dimensional ◽  
Dynamic Features ◽  
Stability Margins ◽  
Mass Eccentricity ◽  
Nonlinear Dynamic Characteristics ◽  
Rotor Bearing ◽  
Rod Fastening Rotor ◽  
Bearing System

The nonlinear dynamic characteristics of three-dimensional rod-fastening rotor bearing system are investigated in this paper. The rod-fastening rotor includes discontinuous shaft, rotating disks, circumferentially distributed rods, and macrointerfaces between disks. The first three parts are discretized by three dimensional elements, and the macrointerfaces are connected by some springs whose stiffness is determined by a proposed linear partition method. For comparison, the three-dimensional dynamic model of a corresponding complete rotor bearing system is also built. After the rod-fastening and complete rotor bearing system are reduced by a component mode synthesis, periodic motions and stability margins are calculated by using the shooting method and path-following technique, and the local stability of system is obtained by using the Floquet theory. Comparative results show the both systems have a resemblance in the bifurcation features when mass eccentricity and rotating speed are changed. The vibration response has the identical frequency components when typical bifurcations occur. The dynamic stress is obtained by regarding the displacements of all nodes as load. Moreover, the unbalanced and insufficient of the pre-tightening forces lead to obvious disadvantageous influence on the stability and vibration of the both systems. Generally, this paper considers the interfacial effect of the rod-fastening rotor bearing system and the relative nonlinear dynamic features are obtained.

scholarly journals Student Learning about Biomolecular Self-Assembly Using Two Different External Representations

2013 ◽  
Vol 12 (3) ◽  
pp. 471-482 ◽  
Author(s):  
Gunnar E. Höst ◽  
Caroline Larsson ◽  
Arthur Olson ◽  
Lena A. E. Tibell
Keyword(s):  
Student Learning ◽  
Self Assembly ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
External Representations ◽  
Three Dimensional Model ◽  
Written Responses ◽  
Significant Difference ◽  
Model Condition ◽  
The Impact

Self-assembly is the fundamental but counterintuitive principle that explains how ordered biomolecular complexes form spontaneously in the cell. This study investigated the impact of using two external representations of virus self-assembly, an interactive tangible three-dimensional model and a static two-dimensional image, on student learning about the process of self-assembly in a group exercise. A conceptual analysis of self-assembly into a set of facets was performed to support study design and analysis. Written responses were collected in a pretest/posttest experimental design with 32 Swedish university students. A quantitative analysis of close-ended items indicated that the students improved their scores between pretest and posttest, with no significant difference between the conditions (tangible model/image). A qualitative analysis of an open-ended item indicated students were unfamiliar with self-assembly prior to the study. Students in the tangible model condition used the facets of self-assembly in their open-ended posttest responses more frequently than students in the image condition. In particular, it appears that the dynamic properties of the tangible model may support student understanding of self-assembly in terms of the random and reversible nature of molecular interactions. A tentative difference was observed in response complexity, with more multifaceted responses in the tangible model condition.

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