Self-Excited Oscillation Analysis of a Multidegree-of-Freedom System With Cubic Non-Linearities: Dynamic Problems in Rolling Mill (IV)

1991 ◽  
Author(s):  
YongDe Chen ◽  
YeYi Xu
Keyword(s):  
Dynamic Model ◽  
Internal Resonance ◽  
Rolling Mill ◽  
The Self ◽  
Dynamic Problems ◽  
Oscillation Analysis ◽  
Excited Oscillation ◽  
Drive Systems ◽  
Almost All ◽  
Zero Frequency

Abstract In nalyzing the self-excited oscillation in drive systems of a rolling mill, almost all of the scholars didn’t consider the internal resonance and zero-frequency. We indicate that these important factors couldn’t be neglected. In this paper, dynamic model is reconstructed, and self-excited oscillation is discussed in the presence of an internal resonance. Several new conclusions are drawn. These results are useful for design of blooming mill drive systems.

Erosion Experiment of Self-Excited Oscillation Pulsed Jet

2014 ◽  
Vol 937 ◽  
pp. 614-619
Author(s):  
Chuan Lin Tang ◽  
Jie Pei ◽  
Dong Hu ◽  
Xiao Ting He
Keyword(s):  
Significant Influence ◽  
Cavity Length ◽  
Experimental Studies ◽  
The Self ◽  
Erosion Depth ◽  
Pulsed Jet ◽  
Excited Oscillation ◽  
Erosion Effect ◽  
Erosion Volume ◽  
Peak Value

In order to improve the erosion effect of jet under submergence condition, experimental studies of erosion generated from the self-excited pulsed jet was carried out by using developed self-excited oscillation nozzle. The erosion volume and depth of pulsed jet were measured and taking mortar block as an erosion part. The results were that the standoff has significant influence on erosion effect. The erosion volume firstly decreases with increases in cavity length and then increases to a peak value. Erosion volume of pulsed jet is significantly higher than that of continuous jet, the erosion depth of two jet has slight difference.

scholarly journals Vibration Characteristics of Hot Rolling Mill Rolls Based on Elastoplastic Hysteretic Deformation

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 869
Author(s):  
Rongrong Peng ◽  
Xingzhong Zhang ◽  
Peiming Shi
Keyword(s):  
Hot Rolling ◽  
Internal Resonance ◽  
Rolling Mill ◽  
Rolling Force ◽  
Subharmonic Resonance ◽  
Force Model ◽  
Maximum Lyapunov Exponent ◽  
Vibration System ◽  
Hot Rolling Mill ◽  
Rolling Mill Vibration

Based on the analysis of the influence of roll vibration on the elastoplastic deformation state of a workpiece in a rolling process, a dynamic rolling force model with the hysteresis effect is established. Taking the rolling parameters of a 1780 mm hot rolling mill as an example, we analyzed the hysteresis between the dynamic rolling force and the roll vibration displacement by varying the rolling speed, roll radius, entry thickness, front tension, back tension, and strip width. Under the effect of the dynamic rolling force and considering the nonlinear effect between the backup and work rolls as well as the structural constraints on the rolling mill, a hysteretic nonlinear vertical vibration model of a four-high hot rolling mill was established. The amplitude-frequency equations corresponding to 1/2 subharmonic resonance and 1:1 internal resonance of the rolling mill rolls were obtained using a multi-scale approximation method. The amplitude-frequency characteristics of the rolling mill vibration system with different parameters were studied through a numerical simulation. The parametric stiffness and nonlinear stiffness corresponding to the dynamic rolling force were found to have a significant influence on the amplitude of the subharmonic resonance system, the bending degree of the vibration curve, and the size of the resonance region. Moreover, with the change in the parametric stiffness, the internal resonance exhibited an evident jump phenomenon. Finally, the chaotic characteristics of the rolling mill vibration system were studied, and the dynamic behavior of the vibration system was analyzed and verified using a bifurcation diagram, maximum Lyapunov exponent, phase trajectory, and Poincare section. Our research provides a theoretical reference for eliminating and suppressing the chatter in rolling mills subjected to an elastoplastic hysteresis deformation.

scholarly journals MAKYUNG AS AN OLDEST FORM OF MALAY TRADITIONAL DANCE THEATRE IN SOUTHEAST ASIA

2019 ◽  
Vol 2 (1) ◽  
pp. 27-35
Author(s):  
Rosdeen Suboh
Keyword(s):  
Southeast Asia ◽  
18Th Century ◽  
The Self ◽  
Oral Traditions ◽  
Historical Records ◽  
Dance Theater ◽  
Exact Date ◽  
Archaeological Materials ◽  
Almost All ◽  
Performance Structure

Almost all previous studies on the Makyung dance theater concurred that the aforementioned performance was the oldest form of traditional theater amongst the Malays in Southeast Asia. It arrived or started before the arrival of Islam to the Malay Peninsula. Unfortunately, the written record on Makyung only existed at the end of the 18th century. Hence, the exact date on the origin of Makyung is difficult to determine. This means that the main sources of research on Makyung are from oral traditions, including myths, as well as the evidence contained in the self-titled performances, and not only depending the sources of writing, material evident or archaeological materials. Consequently, this article offers that Makyung is the oldest dance theatre in Southeast Asia through the analysis of previous historical records, studies and opinions about stories and elements in the performance structure.

scholarly journals MODELLING OF ELECTROMECHANICAL DRIVE SYSTEMS WITH THE USE OF MODAL CONDENSATION

Transport ◽  
2005 ◽  
Vol 20 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Damian Gasiorek ◽  
Arkadiusz Mežyk ◽  
Eugeniusz Switoński
Keyword(s):  
Dynamic Model ◽  
Software Package ◽  
Electromechanical Model ◽  
Electromechanical Drive ◽  
Mechanical Subsystem ◽  
Drive Systems ◽  
Dynamic Phenomena

This paper presents a method of developing a dynamic model enabling the study of the effect of the flexibility of the housing on dynamic phenomena in electromechanical drive systems. The research was performed on the basis of an electromechanical model with feedback between the mechanical subsystem (toothed gear with housing) and the electrical subsystem using a software package developed by the author in MATLAB environment.

Fatigue of Metal Free Reed due to Self-Excited Oscillation

2008 ◽  
Vol 33-37 ◽  
pp. 267-272
Author(s):  
Yoshinobu Shimamura ◽  
Keiichiro Tohgo ◽  
Hiroyasu Araki ◽  
Yosuke Mizuno ◽  
Shoji Kawaguchi ◽  
...  
Keyword(s):  
Fatigue Testing ◽  
The Self ◽  
Fatigue Properties ◽  
Bending Fatigue ◽  
Metal Free ◽  
Mass Damper ◽  
Excited Oscillation ◽  
Analytical Research ◽  
Fatigue Characteristics ◽  
Good Agreement

Metal free reeds are used for musical instruments like harmonica. Free reeds are small, thin cantilevers, and oscillate by blowing air. It is reported that free reeds break due to fatigue during play. In order to elongate the life of free reeds, the fatigue properties should be investigated and a motion analysis method should be developed. The experimental and analytical research on metal free reed, however, has been rarely reported. In this study, two types of fatigue testing machines were developed to obtain basic fatigue characteristics. The fatigue testing machines are designed for bending fatigue of actual free reeds whose thickness is less than 400 μm. An S-N diagram is successfully obtained up to 107 cycles by using the developed fatigue testing machines. The fracture surfaces of fatigued specimens are in good agreement with those of free reeds failed in use. Then, an analytical method for the self-excited oscillation of free reeds was developed based on a mass-damper-spring model. The proposed method can take account for the shape of free reed. The self-excited oscillation of free reeds with different shape are analyzed and in good agreement with experimental results.

A Self-Deployment Hexapod Model for a Space Application

2008 ◽  
Vol 4 (1) ◽  
Author(s):  
G. Aridon ◽  
A. Al Majid ◽  
L. Blanchard ◽  
D. Rémond ◽  
R. Dufour
Keyword(s):  
Numerical Model ◽  
Dynamic Model ◽  
Strain Energy ◽  
The Self ◽  
Hysteretic Behavior ◽  
Simulation Tool ◽  
Space Application ◽  
Tensor Representation ◽  
Restoring Force ◽  
The Impact

This paper presents a simulation tool for predicting the self-deployment of an on-board deployable hexapod based on the release of strain energy stored in six tape-spring actuators. Their hysteretic behavior is described by six restoring force models, and a formulation of a direct dynamic model developed with a Lagrangian approach is performed. Furthermore, tensor representation is used to condense and simplify the calculation of Lagrangian partial derivatives. The results are compared with a numerical model that implements the recursive Newton–Euler technique. Finally, the impact of base excitations on the hexapod deployment performances is evaluated by using the proposed restoring force models.

"The Second New Near"

1993 ◽  
Vol 14 (1) ◽  
pp. 3-3
Keyword(s):  
The Self ◽  
Self Assessment ◽  
The Core ◽  
Core Content ◽  
Second Year ◽  
Almost All

With this volume, Pediatrics In Review begins its second year of publication with the new format and with most of the material being based on the core content statements developed by the American Board of Pediatrics that are the basis of the examination for renewal of certification. Of the more than 3800 such statements so far developed, we covered more than 1000 in 1992 and, more important, more than 300 of the 900 from which the 1993 examination will be based. By mid-1993, Pediatrics in Review plus the self assessment part of PREP will have covered almost all of these core content statements, thereby enabling those who are preparing for the examination to be well-prepared.

Stabilization of a flexible pipe conveying fluid with an active boundary control method

2020 ◽  
Vol 26 (19-20) ◽  
pp. 1824-1834
Author(s):  
Beiming Yu ◽  
Hiroshi Yabuno ◽  
Kiyotaka Yamashita
Keyword(s):  
Flow Velocity ◽  
Control Method ◽  
Bending Moment ◽  
The Self ◽  
Pipe Conveying Fluid ◽  
Stabilization Method ◽  
Critical Flow Velocity ◽  
Complex Eigenvalues ◽  
Excited Oscillation ◽  
Conveying Fluid

A method of stabilizing the self-excited oscillation of a cantilevered pipe conveying fluid because of non–self-adjointness is proposed theoretically and experimentally. Complex eigenvalues denoting the natural frequency and damping of the system vary with an increase in the flow velocity. When the flow velocity exceeds a critical value, the flow-generated damping becomes negative and the pipe is dynamically destabilized. The complex eigenvalues with respect to flow velocity are affected by boundary conditions. We, thus, propose a stabilization control actuating the boundary condition. The stabilization method is carried out by applying a bending moment proportional to the bottom displacement of the pipe. The effect of the proposed control method is shown by investigating the stability for the three lowest modes of the system depending on the feedback gain. It is theoretically clarified that the critical flow velocity is increased by the proposed control method. Furthermore, experiments are performed using a fluid conveying pipe with two piezoactuators at the downstream end. The piezoactuators apply a bending moment at the downstream end of the pipe according to the theoretically proposed method. Experimental results verify that the proposed stabilization method suppresses the self-excited oscillation.

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