Feature investigation of a cracked rotor with initial deflection

2003 ◽  
Vol 217 (7) ◽  
pp. 787-796 ◽  
Author(s):  
J Zou ◽  
J Chen ◽  
G M Dong
Keyword(s):  
Numerical Simulation ◽  
Dynamic Equation ◽  
Subharmonic Resonance ◽  
Initial Deflection ◽  
Crack Model ◽  
Cracked Rotor ◽  
Simulation Research ◽  
Vibrational Characteristics ◽  
Frequency Components ◽  
Stiffness Variation

The dynamic equation of a cracked rotor with initial deflection is modelled, which is based on the simple hinge crack model; the numerical simulation solutions are obtained from the model. The subharmonic resonance of the cracked rotor is analysed and the frequency components of the cracked rotor with initial deflection and without initial deflection are investigated. By simulation research, the influence of the stiffness variation, the initial deflection, the unbalance, the unbalance angle and the orientation of the initial deflection on the vibrational characteristics is studied, which can be used as the criterion for identification of a cracked rotor.

Application of the Wigner-Ville distribution to identification of a cracked rotor

2003 ◽  
Vol 217 (5) ◽  
pp. 551-556 ◽  
Author(s):  
J Zou ◽  
J Chen ◽  
J C Niu ◽  
Z M Geng
Keyword(s):  
Numerical Simulation ◽  
Transient Response ◽  
Crack Model ◽  
Cracked Rotor ◽  
Simulation Research ◽  
Time Frequency ◽  
Stiffness Variation ◽  
Engineering Practices ◽  
Frequency Features ◽  
Frequency Feature

The dynamic equation of transient response in a cracked rotor is modelled, and is based on the simple hinge crack model. The numerical simulation solutions of the uncracked rotor and the cracked rotor are obtained from the model. Using the Wigner-Ville distribution, the time-frequency features of the cracked rotor and the uncracked rotor are compared, and a new algorithm using the Wigner-Ville distribution to identify the cracked rotor is proposed. By simulation research, the sensitivity of the Wigner-Ville distribution to the stiffness variation is investigated, and the influence of the unbalance and the inhabiting angle on the time-frequency feature is discussed. The Wigner-Ville time-frequency feature is unique, and can be used as the criterion for identification of a cracked rotor in engineering practices.

Study on the transient response and wavelet time—frequency feature of a cracked rotor passage through a subcritical speed

2003 ◽  
Vol 38 (3) ◽  
pp. 269-276 ◽  
Author(s):  
J Zou ◽  
J Chen ◽  
J. C Niu ◽  
Z. M Geng
Keyword(s):  
Numerical Simulation ◽  
Transient Response ◽  
Crack Model ◽  
Cracked Rotor ◽  
Time Frequency ◽  
Stiffness Variation ◽  
The Difference ◽  
Frequency Features ◽  
Cracked Rotor System ◽  
Subcritical Speed

The dynamic model in dimensionless form of the transient response of a cracked rotor system is derived, which is based on the simple hinge crack model. By numerical simulation, the transient responses of the uncracked rotor and the cracked rotor are obtained and the subharmonic resonance of the cracked rotor is analysed. The influence of the unbalance, the inhabiting angle and the stiffness variation on the transient response is investigated. The wavelet time-frequency features of the cracked rotor and the uncracked rotor are studied, and the difference between them is discussed. The numerical simulation demonstrates that the wavelet analysis algorithm is valid for the identification of cracked rotor.

On the wavelet time-frequency analysis algorithm in identification of a cracked rotor

2002 ◽  
Vol 37 (3) ◽  
pp. 239-246 ◽  
Author(s):  
J Zou ◽  
J Chen ◽  
Y P Pu ◽  
P Zhong
Keyword(s):  
Numerical Simulation ◽  
Detection Algorithm ◽  
Sampling Frequency ◽  
Crack Model ◽  
Cracked Rotor ◽  
Simulation Research ◽  
Time Frequency ◽  
Local Flexibility ◽  
The Difference ◽  
Frequency Properties

Based on the hinge crack model and the local flexibility theorem, the local flexibility of a cracked rotor due to the crack and the modified function of the opening and closing of the crack are given; the corresponding dynamic equation of the cracked rotor is modelled; the numerical simulation solutions of the cracked rotor and the uncracked rotor are obtained. By the continuous wavelet time—frequency transform, the wavelet time-frequency properties of the uncracked rotor and the cracked rotor are discussed; the difference between the wavelet time-frequency properties of the cracked rotor and those of the uncracked rotor is presented. A new detection algorithm that uses the wavelet time-frequency transform to identify the crack is proposed. The influence of the sampling frequency on the accuracy and validity of the wavelet time-frequency transform is analysed by numerical simulation research; the preferred sampling frequency is suggested. The experiments on the cracked rotor and the uncracked rotor demonstrate the validity and availability of the algorithm in the identification of the cracked rotor in engineering practices.

Effect of Unbalance Force Direction on a Cracked Rotor Whirl Response

2017 ◽  
Author(s):  
Hanan Al Hosani ◽  
Mohammad A. AL-Shudeifat ◽  
Adnan S. Saeed ◽  
Shadi Balawi
Keyword(s):  
Numerical Simulation ◽  
Crack Opening ◽  
Crack Model ◽  
Open Crack ◽  
Cracked Rotor ◽  
Force Vector ◽  
Critical Speeds ◽  
Unbalance Force ◽  
Vector Angle ◽  
Time Periodic

The combined effect of the crack and the unbalance force vector angle on the values and locations of the whirl amplitudes at the critical whirl speeds for a cracked rotor-bearing-disk system is numerically and experimentally investigated here. The strongly nonlinear time-periodic equations of motion, which are analogous to Mathieus equation, of the cracked system with an open crack model are formulated according to the finite element time-periodic stiffness matrix. The whirl response during the passage through the critical speeds is obtained via numerical simulation for different unbalance vector angles with respect to the crack opening direction. It is found that the variation in the unbalance force vector angle with respect to the crack opening direction significantly alters the peaks of the critical whirl amplitudes and their corresponding critical whirl speeds. Consequently, the critical speeds of the cracked rotor are either shifted to higher or lower values according to the unbalance force vector angle value. These significant numerical simulation observations are also verified via robust experimental results.

scholarly journals Numerical Simulation Research on Multi-field Coupling of Underground Energy Pile

2021 ◽  
Vol 1838 (1) ◽  
pp. 012061
Author(s):  
Qihui Zhou ◽  
Zhanjun Huang ◽  
Yong Wu ◽  
Huipeng Zhang ◽  
Yufeng Shi ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Simulation Research ◽  
Energy Pile ◽  
Field Coupling

Simulation Research on Control Technology of Micro-Particle Adhesion to Surface

2011 ◽  
Vol 181-182 ◽  
pp. 366-371
Author(s):  
Hui Liu ◽  
Yan Qiang Li
Keyword(s):  
Numerical Simulation ◽  
Electrostatic Force ◽  
Actual State ◽  
Control Technology ◽  
Particle Adhesion ◽  
Adhesion Mechanism ◽  
Simulation Research ◽  
Mechanical Models ◽  
Analysis Of Results ◽  
Simulation Package

The micro particle brings much harm to some industrials, agriculture and human activities. The mechanical models of micro particle adhesion to the surface and the control, disposal technology have become very important for prevention from particle aggradations. For the sake of deeply comprehending and researching the adhesion mechanism as well as kinematics characteristic, numerical simulation of particle adhesion was made based on compute simulation package, the analysis of results and relevant comparison demonstrate that it can well simulate actual state and the results of simulation show that the capillary force (Fc) is the biggest, by contrast, the electrostatic force (Fes) is the smallest. Further more, it has some valuable instructions and helpful references for control of micro-particle adhesion to surface. At last, the outlook of issue was put forward.

Numerical Simulation Research on the Shape of Top Coal Drawn-Body in Gently Inclined Seam

2012 ◽  
Vol 468-471 ◽  
pp. 2248-2254
Author(s):  
Qiang Li ◽  
Wan Kui Bu ◽  
Hui Xu ◽  
Xiao Bo Song
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Random Medium ◽  
Body Movement ◽  
The Other ◽  
Simulation Research ◽  
Research Results ◽  
Shape Equation ◽  
The Difference ◽  
Meso Scale

The numerical model of top coal drawing in gently inclined seam is built based on PFC2d software. By comparing with the theory of drawn-body movement law, it can be obtained that the shape of top coal drawn-body accords with the theory of random medium movement. The research results show that the form of the shape equation of top coal drawn-body is uniform while the top coal caving angle is different. On the other hand, with the difference of top coal caving angle and drawing height, the shape of top coal drawn-body is differential at the meso scale, which depends on the parameters of the shape equation of top coal drawn-body.

Numerical Simulation Research on Springback Controlling Methods of Aluminum Alloy Panel during Hydroforming

2016 ◽  
Vol 851 ◽  
pp. 163-167
Author(s):  
Dong Yan Lin ◽  
Yi Li
Keyword(s):  
Numerical Simulation ◽  
Aluminum Alloy ◽  
Process Parameters ◽  
Orthogonal Experiment ◽  
Blank Holder Force ◽  
Scoring Method ◽  
Simulation Research ◽  
Blank Holder ◽  
Hydroforming Process

The hydroforming process of the aluminum alloy panel was simulated by the software DYNAFORM. The effects of process parameters (blank holder force, depth of panel and height of draw bead) on springback of the aluminum alloy were investigated. The max springback of the panel was analyzed by weighted scoring method. Then the process parameters were synthetically optimized for the max positive and negative springback. The results showed that the height of draw bead affects obviously the comprehensive springback of the panel. The optimization of the process parameters obtained by the orthogonal experiment can effectively reduce the max springback of the panel.

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