scholarly journals A Rocking/Rolling Half-Disk Vibratory System

2018 ◽  
Author(s):  
Jeffrey Hayen
Keyword(s):  
Vibratory System ◽  
Half Disk

scholarly journals Modeling of Piezoelectric Energy Harvesting from Freely Oscillating Cylinders in Water Flow

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Min Zhang ◽  
YingZheng Liu ◽  
ZhaoMin Cao
Keyword(s):  
Energy Harvesting ◽  
Free Stream ◽  
Piezoelectric Materials ◽  
Load Resistance ◽  
Stream Velocity ◽  
Piezoelectric Energy Harvesting ◽  
Vibratory System ◽  
System Parameters ◽  
Piezoelectric Energy ◽  
Vortex Induced Vibrations

A concept of energy harvesting from vortex-induced vibrations of a rigid circular cylinder with two piezoelectric beams attached is investigated. The variations of the power levels with the free stream velocity are determined. A mathematical approach including the coupled cylinder motion and harvested voltage is presented. The effects of the load resistance, piezoelectric materials, and circuit combined on the natural frequency and damping of the vibratory system are determined by performing a linear analysis. The dynamic response of the cylinder and harvested energy are investigated. The results show that the harvested level in SS and SP&PS modes is the same with different values of load resistance. For four different system parameters, the results show that the bigger size of cylinder with PZT beams can obtain the higher harvested power.

Second Order Averaging Study of an Autoparametric System

1993 ◽  
Author(s):  
Bappaditya Banerjee ◽  
Anil K. Bajaj ◽  
Patricia Davies
Keyword(s):  
Dynamical Behavior ◽  
Period Doubling ◽  
Nonlinear Effects ◽  
Single Mode ◽  
Pitchfork Bifurcation ◽  
Second Order ◽  
System Response ◽  
Response Curves ◽  
Vibratory System ◽  
First Order

Abstract The autoparametric vibratory system consisting of a primary spring-mass-dashpot system coupled with a damped simple pendulum serves as an useful example of two degree-of-freedom nonlinear systems that exhibit complex dynamic behavior. It exhibits 1:2 internal resonance and amplitude modulated chaos under harmonic forcing conditions. First-order averaging studies of this system using AUTO and KAOS have yielded useful information about the amplitude dynamics of this system. Response curves of the system indicate saturation and the pitchfork bifurcation sets are found to be symmetric. The period-doubling route to chaotic solutions is observed. However questions about the range of the small parameter ε (a function of the forcing amplitude) for which the solutions are valid cannot be answered by a first-order study. Some observed dynamical behavior, like saturation, may not persist when higher-order nonlinear effects are taken into account. Second-order averaging of the system, using Mathematica (Maeder, 1991; Wolfram, 1991) is undertaken to address these questions. Loss of saturation is observed in the steady-state amplitude responses. The breaking of symmetry in the various bifurcation sets becomes apparent as a consequence of ε appearing in the averaged equations. The dynamics of the system is found to be very sensitive to damping, with extremely complicated behavior arising for low values of damping. For large ε second-order averaging predicts additional Pitchfork and Hopf bifurcation points in the single-mode response.

scholarly journals Identification of Acoustic-Vibratory System by Acoustic Measurement

1996 ◽  
Vol 3 (1) ◽  
pp. 27-37
Author(s):  
Takuzo Iwatsubo ◽  
Shozo Kawamura ◽  
Masahito Kamada
Keyword(s):  
Inverse Analysis ◽  
Coefficient Matrix ◽  
Superposition Method ◽  
Vibration Modes ◽  
Identification Problems ◽  
Mathematical Property ◽  
Vibratory System ◽  
Stochastic Error ◽  
Mode Superposition Method ◽  
Ill Conditioning

A new method for reducing ill-conditioning in a class of identification problems is proposed. The key point of the method is that the identified vibration of the sound source is expressed as a superposition of vibration modes. The mathematical property of the coefficient matrix, the practical error expanding ratio, and the stochastic error expanding ratio are investigated in a numerical example. The mode-superposition method is shown to be an effective tool for acoustic-vibratory inverse analysis.

scholarly journals Estimation of rolling bearing life with damage curve approach

2011 ◽  
Vol 18 (3) ◽  
pp. 66-70 ◽  
Author(s):  
H. Mehdigholi ◽  
H. Rafsanjani ◽  
Behzad Mehdi
Keyword(s):  
Natural Frequency ◽  
Damage Mechanics ◽  
Calculated Data ◽  
Life Time ◽  
Rolling Bearing ◽  
Vibratory System ◽  
Outer Race ◽  
Bearing Life ◽  
Proposed Model ◽  
Acceleration Amplitude

Estimation of rolling bearing life with damage curve approach The ability to determine the bearing life time is one of the main purposes in maintenance of rotating machineries. Because of reliability, cost and productivity, the bearing life time prognostic is important. In this paper, a stiffness-based prognostic model for bearing systems is discussed. According to presumed model of bearing and fundamental of damage mechanics, damage curve approach is used to relate stiffness of vibratory system and bearing running life. Furthermore, using the relation between acceleration amplitude at natural frequency and stiffness, final relation between acceleration amplitude at natural frequency and running life time according to damage curve approach can be established and the final running time is predicted. Experiments have been performed on self alignment bearing under failures on inner race and outer race to calibrate and to validate the proposed model. The comparison between model-calculated data and experimental results indicates that this model can be used effectively to predict the failure lifetime and the remaining life of a bearing system.

Connectivity of certain simplicial complexes associated to a handlebody

2016 ◽  
Vol 25 (11) ◽  
pp. 1650064 ◽  
Author(s):  
Qilong Guo ◽  
Qing Liu
Keyword(s):  
Simplicial Complexes ◽  
Pants Graph ◽  
Half Disk ◽  
Disk Complex

In this paper, we prove three simplicial complexes associate to a handlebody, which are separating disk complex, half disk complex and disk pants graph, are connected.

A Precision Pruning Strategy for Improving Efficiency of Vibratory Mechanical Harvesting of Apples

2018 ◽  
Vol 61 (5) ◽  
pp. 1565-1576 ◽  
Author(s):  
Xin Zhang ◽  
Long He ◽  
Yaqoob Majeed ◽  
Matthew David Whiting ◽  
Manoj Karkee ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Fruit Quality ◽  
Negative Relationship ◽  
Fresh Market ◽  
Fruit Removal ◽  
Vibratory System ◽  
Significant Difference ◽  
Labor Requirements ◽  
Lateral Branches ◽  
Canopy Management

Abstract. The state of Washington is the biggest fresh market apple ( Borkh.) producer in the U.S., and the state’s annual apple production has exceeded 60% of the national production. Due to the extensive labor requirements for harvesting fresh market apples, there is burgeoning demand for mechanical harvest solutions. Our transdisciplinary studies on mechanical harvest systems for apples have shown that fruit removal efficiency (FRE) with a vibratory system can be improved with precision canopy management. In this study, we evaluated the effect of precision pruning strategies on FRE in two groups (106 and 107, respectively) of randomly selected horizontal branches of ‘Jazz/M.9’ apple trees in a commercial orchard. Fruiting lateral branches were pruned to either shorter than 15 cm (guideline 1, G1) or 23 cm (guideline 2, G2). Harvest tests were conducted using a shake-and-catch harvester prototype developed by Washington State University with a fixed vibrating frequency of 20 Hz and shaking duration of 5 s. FRE for branches treated with G1 was significantly higher (91%) than FRE for branches treated with G2 (81%). We recorded a negative relationship between FRE and lateral shoot length. FRE was up to 98% when shoots were shorter than 5 cm, and FRE was only 56% for shoots of 25 cm or longer. We developed a shoot diameter-to-length index (S-index) to better understand the effect of shoot size on FRE. FRE was as high as 98% when the S-index was greater than 0.15. In addition, mechanically harvested fruit quality was assessed by categorizing the fruit into Extra Fancy, Fancy, and Downgrade fresh market classes based on USDA standards; however, no significant difference was found between the two treated groups. These results suggest that pruning lateral fruiting branches to less than 15 cm or to an S-index greater than 0.03 is required to achieve FRE of 85% with no negative impacts on fruit quality. Keywords: Canopy management, Fresh market fruit, Fruit removal efficiency, Mechanical harvest, Shoot pruning severity.

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