New Methods for the Dynamic Analysis of Flexible Single-Input and Multi-Input Cam-Follower Systems

Dresner, Thomas L.; Barkan, P.

doi:10.1115/1.2826100

Cited by 17 publications

(7 citation statements)

References 17 publications

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“…The torque on cam, T cam , and torque on flywheel, T flywheel , are same as torque on driven‐gear since they are fixed to the same shaft (i.e., T cam = T flywheel = T gear ). The cam and vibration system behaves like a typical cam–follower . When the cam is in contact with the follower, it will experience a resistive torque, T follower , acting opposite to the direction of cam rotation.…”

Section: Resultsmentioning

confidence: 99%

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Design of Mechanical Frequency Regulator for Predictable Uniform Power from Triboelectric Nanogenerators

Bhatia

Lee

Hwang

et al. 2018

Advanced Energy Materials

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unpredictable. Finally, the unpredictability in converted electrical output makes it difficult to design circuits for optimal electrical energy storage and transforma tion. Thus, the entire performance of the energy scavenging power system is com promised if the problem of input mecha nical energy irregularity is not resolved.Triboelectric nanogenerators (TENG) can scavenge ambient mechanical vibra tion and rotation energy. They can be manufactured at low cost without any nanoprocessing, or performance can be enhanced by introducing nanopatterns on the tribosurfaces. [10,11] Typically, the TENG output increases with increase in input force, and it is sensitive to changes in input frequency. [12][13][14] Some studies have used the TENG sensitivity to frequency for sensor applica tions. [15][16][17] The input frequency also affects the TENG imped ance. [18,19] The optimal load capacitor for TENG energy storage is also frequency dependent. [20,21] In order to charge a battery, with low internal impedance, the inherent high impedance of the TENG must be reduced using a transformer. [18] Transformer conversion can lower TENG impedance, stepup the low TENG current, and stepdown the high TENG voltage. Using a trans former with the TENG can also enhance the rate of charging a large capacitor. [22][23][24] Transformers, however, are designed to operate optimally at specific frequencies. For example, iso lation transformers and power conversion transformers are designed to operate at 50/60 Hz to be compatible with the elec tric grid. [25] Thus, in order to use transformer with the TENG it is imperative to reliably regulate the TENG output frequency. Studies that have successfully employed the transformer with the TENG used highfrequency input conditions, which may not be consistently available especially when the mechanical input energy is irregular or low frequency. [18,19,[22][23][24] Therefore, by controlling the input forces and frequency acting on the TENG, first, the TENG internal impedance and output can be made predictable; second, sensible selection of load capacitor for direct charging is possible; and third, optimal use of trans former with the TENG for impedance matching, or voltage and current conversion is made possible.In this work, we introduce a mechanical frequency regulator (MFR) to obtain predictable uniform output from the TENG despite changes in the external input. First, handdriven input rotation energy of variable and low frequency was stored in a spiral spring (or mainspring). Then, the stored energy was Mechanical energy scavengers convert irregular input mechanical energy into irregular electrical output. There is a need to enable uniform and predictable electric output from energy scavengers regardless of the variability in the mechanical input. So, in this work, a mechanical frequency regulator is proposed that fixes the input forces and input frequency acting on a triboelectric nanogenerator, thus enabling predictable electric output. The irregular low frequency mechanical input energy is firs...

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Section: Resultsmentioning

confidence: 99%

“…The cam and vibration system behaves like a typical cam-follower. [26,27] When the cam is in con tact with the follower, it will experience a resistive torque, T follower , acting opposite to the direction of cam rotation. If T follower is too large due to high spring stiffness, then the cam will not rotate.…”

Section: Figure 2amentioning

confidence: 99%

Design of Mechanical Frequency Regulator for Predictable Uniform Power from Triboelectric Nanogenerators

Bhatia

Lee

Hwang

et al. 2018

Advanced Energy Materials

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“…In the case of cam-follower systems, various models have been proposed characterized by different degrees of complexity, ranging from simple models with 1 DOF (Degree of Freedom) [28] to complex models with 21 DOF [43] that use the additional DOF to include the effects of camshaft torsion and bending, backlash, squeeze of lubricant in bearings and so on. Nevertheless, there is general agreement, confirmed by experience in different applications, that a lumped parameter single degree of freedom model is adequate to represent most aspects of the dynamic behaviour of a cam-follower system (for example, see [2,4,21,28]). …”

Section: Mathematical Modellingmentioning

confidence: 88%

“…Finally, expression (14) in Section 4.2 can be obtained by substituting (19), (21) and (23) into Equation (13).…”

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confidence: 99%

Experimental and numerical verification of bifurcations and chaos in cam-follower impacting systems

et al. 2007

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In this paper we present the design, modelling and experimental validation of a novel experimental cam-follower rig for the analysis of bifurcations and chaos in piecewise-smooth dynamical systems with impacts. Experimental results are presented for a cam-follower system characterized by a radial cam and a flat-faced follower. Under variation of the cam rotational speed, the follower is observed to detach from the cam and then show the emergence of periodic impacting behaviour characterized by many impacts and chattering. Further variations of the cam speed cause the sudden transition to seemingly aperiodic behaviour. These results are compared with the numerical simulation of a mathematical model of the system which shows the same qualitative behaviour. Excellent quantitative agreement is found between the numerical and experimental results

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“…In general, cam-follower systems can be thought of as impact oscillators with moving boundaries [20,30,15,40]. While the dynamics of impact oscillators with continuous forcing has been the subject of many papers in the existing literature (see for example [32], [17], [6,7]), the possible intricate bifurcation behaviour of impact oscillators with discontinuous forcing was discussed only recently, as for example in [8].…”

Section: Introductionmentioning

confidence: 99%

Corner-Impact Bifurcations: a novel class of discontinuity-induced bifurcations in Cam-Follower Systems

Osorio,

di Bernardo,

Santini

2007

Preprint

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This paper is concerned with the analysis of a class of impacting systems of relevance in applications: cam-follower systems. We show that these systems, which can be modelled as discontinuously forced impact oscillators, can exhibit complex behaviour due to the detachment at high rotational speeds between the follower and the cam. We propose that the observed phenomena can be explained in terms of a novel type of discontinuityinduced bifurcation, termed as corner-impact. We present a complete analysis of this bifurcation in the case of non-autonomous impact oscillator and explain the transition to chaos observed in a representative cam-follower example. The theoretical findings are validated numerically.

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New Methods for the Dynamic Analysis of Flexible Single-Input and Multi-Input Cam-Follower Systems

Cited by 17 publications

References 17 publications

Design of Mechanical Frequency Regulator for Predictable Uniform Power from Triboelectric Nanogenerators

Design of Mechanical Frequency Regulator for Predictable Uniform Power from Triboelectric Nanogenerators

Experimental and numerical verification of bifurcations and chaos in cam-follower impacting systems

Corner-Impact Bifurcations: a novel class of discontinuity-induced bifurcations in Cam-Follower Systems

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