Rectification of Piezoelectric Dynamometer Force Signals During Low Frequency Vibration Assisted Drilling

2013 ◽  
Author(s):  
A. Sadek ◽  
M. Meshreki ◽  
M. H. Attia
Keyword(s):  
Transfer Function ◽  
Degrees Of Freedom ◽  
Research Work ◽  
Low Frequency ◽  
High Amplitude ◽  
Force Transducer ◽  
Dynamic Force ◽  
Low Frequency Vibration ◽  
Measured Force ◽  
Force Components

In vibration assisted drilling (VAD), a controlled harmonic motion is superimposed over the principal drilling feed motion in order to create an intermittent cutting state, which reduces cutting forces and temperatures, facilitates chip removal, and increases the possibility for dry machining. However, accurate force measurements during VAD operations has been a challenge especially in systems, where the force transducer is part of the vibrating mass mounted on the shaker head, due to the dynamic force errors. Conventional signal filtering and compensation techniques were found to be not applicable for attenuating undesirable VAD dynamic force components, which exist in the measured force signals at the same frequency of superimposed modulation. This research work presents a corrective dynamic model that rectifies the erroneous VAD tangential and axial force signals measured by a commercial piezoelectric dynamometer mounted on electro-magnetic shakers for the low frequency/high amplitude (LF/HA) regime. An experimental modal analysis in tangential and axial directions was conducted in order to define the transfer function of a multiple degrees of freedom VAD system mounted on a vibrating base (shaker). The rectified force is then obtained by plugging the relative motion between the dynamometer base and face measured during cutting into the system transfer function. The predicted rectified force components showed very high conformance with known impact and sinusoidal excitation forces used for validation. Moreover, the developed corrective model was capable of predicting some features in the VAD force signals that were not fully captured in the measured force signals during cutting.

Numerical Model for Prediction of Cutting Forces in a Vibratory Drilling Process

2014 ◽  
Vol 1016 ◽  
pp. 215-220 ◽  
Author(s):  
Nawel Glaa ◽  
Kamel Mehdi ◽  
Moez Ben Jaber
Keyword(s):  
Cutting Forces ◽  
Three Dimensional ◽  
Low Frequency ◽  
Cutting Parameters ◽  
Forced Vibrations ◽  
Drilling Process ◽  
Drilling Operation ◽  
Low Frequency Vibration ◽  
Cutting Force Components ◽  
Force Components

The drilling operation is considered by manufacturers as complex and difficult process (rapid wear of the cutting edge as well as problems of chip evacuation). Faced with these failures, manufacturers have shifted in recent years towards the drilling process assisted by forced vibrations. This method consist to add an axial oscillation with a low frequency to the classical feed movement of the drill so as to ensure good fragmentation and better chip evacuation. This paper presents a model for prediction of cutting forces during a drilling operation assisted by forced low-frequency vibration. The model allows understanding the interaction between the tool and the workpiece and identifying numerically the three-dimensional evolution of the cutting force components generated by the vibratory drilling operation. The effects of cutting parameters, tool parameters and those of forced vibrations on the cutting forces distributions will be discussed.

Sea Motion Simulation, Very Low Frequency Vibration, and Motion Sickness

1976 ◽  
Vol 20 (20) ◽  
pp. 462-462
Author(s):  
Michael E. McCauley
Keyword(s):  
Motion Sickness ◽  
Degrees Of Freedom ◽  
Low Frequency ◽  
Vertical Motion ◽  
Basic Research ◽  
Future Research ◽  
Naval Research ◽  
Low Frequency Vibration ◽  
Office Of Naval Research ◽  
Linear Oscillation

The office of Naval Research/Human Factors Research (ONR/HFR) Motion Generator was designed with three degrees of freedom (heave, pitch, and roll) to simulate the motion of an air-sea craft in varying ocean conditions through Sea State 5. Recent upgrading of the device has provided the capability for simulating the motion of advanced design sea craft as well as certain aspects of vertical motion common to land, sea, and air vehicles. Since 1968, the simulator has been used for investigation of the following topics: (1) basic research to provide equations for the prediction of motion sickness incidence based on parameters of vertical linear oscillation, (2) crew performance during simulated motion of two types of proposed naval vessels, and (3) evaluation of the efficacy of antimotion sickness medications in alleviating the symptoms of motion sickness. This simulator provides the opportunity for future research on the effects of motion on physiological and psychological processes as well as task performance.

A Six Degrees-of-Freedom Vibration Isolation Platform Supported by a Hexapod of Quasi-Zero-Stiffness Struts

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Jiaxi Zhou ◽  
Kai Wang ◽  
Daolin Xu ◽  
Huajiang Ouyang ◽  
Yingli Li
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Permanent Magnets ◽  
Low Frequency ◽  
Harmonic Balance Method ◽  
Dynamic Responses ◽  
Six Degrees Of Freedom ◽  
Low Frequency Vibration ◽  
Force Moment ◽  
Vibration Isolation Performance

A platform supported by a hexapod of quasi-zero-stiffness (QZS) struts is proposed to provide a solution for low-frequency vibration isolation in six degrees-of-freedom (6DOFs). The QZS strut is developed by combining a pair of mutually repelling permanent magnets in parallel connection with a coil spring. Dynamic analysis of the 6DOFs QZS platform is carried out to obtain dynamic responses by using the harmonic balance method, and the vibration isolation performance in each DOF is evaluated in terms of force/moment transmissibility, which indicates that the QZS platform perform a good function of low-frequency vibration isolation within broad bandwidth, and has notable advantages over its linear counterpart in all 6DOFs.

scholarly journals Effects of Low-Frequency Vibration on Physiological Recovery from Exhaustive Exercise

2017 ◽  
Vol 10 (1) ◽  
pp. 87-96
Author(s):  
Ching-Feng Cheng ◽  
Yen-Ling Lu ◽  
Yi-Chen Huang ◽  
Wei-Chieh Hsu ◽  
Yu-Chi Kuo ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Effect Size ◽  
Recovery Period ◽  
Lactate Concentration ◽  
Low Frequency ◽  
Blood Lactate Concentration ◽  
High Amplitude ◽  
Exhaustive Exercise ◽  
Low Frequency Vibration ◽  
Amplitude Vibration

Objective: This study examined the effects of low-frequency vibration on physiological recovery from exhaustive exercise. Methods: Twelve college males were recruited in this randomized crossover-designed study, and were asked to perform one of three treatments following a graded cycling exercise test: nonvibration (0 Hz, 0 mm, CON), high-amplitude vibration (8 Hz, 8 mm, HVT), or low-amplitude vibration (8 Hz, 2 mm, LVT). After the 10-min treatment, participants were asked to rest in a supine position for a 1-h recovery. The oxygen uptake, heart rate (HR), and blood lactate concentration (La) were measured during the trials. Results: The oxygen uptake during HVT were significantly higher than those in the CON and LVT (p < 0.05, effect size = 1.52−1.63). The La immediately following HVT was significantly lower than that following CON (HVT vs. CON = 11.52 ± 1.85 vs. 12.95 ± 1.78 mmol•L-1, p < 0.05, effect size = 1.94). Additionally, the Las following HVT and LVT at the post 30-min were significantly lower than that following the CON (HVT vs. LVT vs. CON = 4.72 ± 0.97 vs. 4.58 ± 1.06 vs. 5.98 ± 1.49 mmol•L-1, p < 0.05). No significant differences were found on the HRs, or on the time and frequency domain indices of HR variability among treatments during the recovery period. Conclusion: These results indicated that vibration with low frequency (8 Hz) can facilitate the removal of metabolic by-products after exhaustive exercise, but it has little effect on the autonomic nervous modulation of HR recovery.

Studies on the low frequency vibration of the suspension system for heavy trucks under different operation conditions

2020 ◽  
pp. 095745652094827 ◽  
Author(s):  
Renqiang Jiao ◽  
Vanliem Nguyen
Keyword(s):  
Degrees Of Freedom ◽  
Low Frequency ◽  
Load Condition ◽  
Surface Profile ◽  
Vertical Vibration ◽  
Vibration Characteristics ◽  
Suspension System ◽  
Operation Conditions ◽  
Low Frequency Vibration ◽  
Heavy Truck

This study proposed a 4 degrees of freedom dynamic model for the two-axle heavy truck to investigate the low frequency vibration characteristics of the suspension system. Unlike the previous research works, the vibration equations of heavy truck model were solved in the frequency domain instead of the traditional time domain based on a calculation method in the complex domain. In order to evaluate the vibration characteristics of the suspension system, parameters of the vehicle velocity, wavelength of the road, load condition, stiffness coefficient, and height of the random road surfaces were then taken into account to clarify their influence on the acceleration frequency characteristics of the suspension system, respectively. The simulation results reveal that the resonant frequency of the suspension system was not affected by the vehicle velocities and road surface profile, while it is greatly influenced by the loading conditions and stiffness of the suspension system. In addition, under different working conditions, the acceleration frequency response characteristics of the vertical and pitch vibration of the heavy truck body and the vertical vibration of the front and rear axles were greatly affected, especially when the vehicle was traveling on the rod of level C at a speed of 30 m s−1.

A New Approach of Formulating the Transfer Function for Dynamic Cutting Processes

1989 ◽  
Vol 111 (1) ◽  
pp. 37-47 ◽  
Author(s):  
D. W. Wu
Keyword(s):  
Transfer Function ◽  
Deformation Zone ◽  
Chip Thickness ◽  
Cutting Process ◽  
Elastic Behavior ◽  
Plastic State ◽  
Dynamic Force ◽  
Machining System ◽  
Force Components ◽  
Cutting Processes

The dynamics of a cutting process are very complex in nature. It involves not only the changes of plastic state in the intensive deformation zone but also the elastic behavior of work material surrounding the deformation zone, especially in the vicinity of the tool nose region. These changes are induced by the inner and outer modulations of the uncut chip thickness during the process and at the same time govern the variation of the cutting force. Based on these causal relationships, the transfer function between the vibration variables and the dynamic force components for a single degree-of-freedom machining system has been developed. The characterization of the mechanics of the cutting process by the new model provides more insight into the physics of the cutting dynamics. The model has been tested through computer simulation for both orthogonal wave-generating and wave-removing processes. By reference to existing experimental evidence, the theoretical predictions show a very good agreement with the test results.

scholarly journals Baroreflexes of the rat. VI. Sleep and responses to aortic nerve stimulation in the dmNTS

2010 ◽  
Vol 298 (5) ◽  
pp. R1428-R1434 ◽  
Author(s):  
Xiaorui Tang ◽  
Barry R. Dworkin
Keyword(s):  
Nerve Stimulation ◽  
Degrees Of Freedom ◽  
Slow Wave Sleep ◽  
Low Frequency ◽  
Single Pulse ◽  
High Amplitude ◽  
Eeg Activity ◽  
Medial Nucleus ◽  
Aortic Depressor Nerve ◽  
Low Amplitude

The sensitivity of the baroreflex determines its stability and effectiveness in controlling blood pressure (BP). Sleep and arousal are reported to affect baroreflex sensitivity, but the findings are not consistent across studies. After statistically correcting the effect of sleep on the baselines in chronically neuromuscular-blocked (NMB) rats, we found that sleep affects BP and heart period (HP) baroreflex gain similarly. This finding is consistent with baroreflex modulation of HP and BP before divergence of the sympathetic and parasympathetic pathways. Therefore, we hypothesized that the gain modulation occurs in the dorsal medial nucleus of the solitary tract (dmNTS). The present study used long-term dmNTS recordings in NMB rats and single-pulse aortic depressor nerve stimulation. Under these conditions, the magnitude of A-fiber evoked responses (ERs), recorded from second- or higher-order dmNTS baroreflex neurons, was reliably augmented during high-amplitude low-frequency EEG activity (slow-wave sleep) and reduced during low-amplitude high-frequency EEG activity (arousal; ΔER = 11%, t = 9.49, P < 0.001, degrees of freedom = 1,016). This result has methodological implications for techniques that use changes in HP to estimate baroreflex BP gain and general implications for understanding the relationship between sleep and cardiovascular control.

An Experimental Study of Low-Frequency Vibration-Based Electromagnetic Energy Harvesters Used while Walking

2014 ◽  
Vol 918 ◽  
pp. 106-114 ◽  
Author(s):  
Min Chie Chiu ◽  
Ying Chun Chang ◽  
Long Jyi Yeh ◽  
Chiu Hung Chung ◽  
Chen Hsin Chu
Keyword(s):  
Kinetic Energy ◽  
Energy Harvester ◽  
Electrical Power ◽  
Research Work ◽  
Low Frequency ◽  
Electrical Energy ◽  
Electromagnetic Energy ◽  
Electromagnetic System ◽  
Energy Harvesters ◽  
Low Frequency Vibration

The goal of this paper is to develop and experimentally test portable vibration-based electromagnetic energy harvesters which are fit for extracting low frequency kinetic energy. Based on a previous study on fixed vibration-based electromagnetic energy harvesters, three kinds of portable energy harvesters (prototype I, prototype II, and prototype III) are developed and tested. To obtain the related parameters of the energy harvesters, an experimental platform used to measure the vibrational systems electrical power at the resonant frequency and other fixed frequencies is also established. Based on the research work of vibration theory, a low frequency vibration-arm mechanism (prototype III) which is easily in resonance with a walking tempo is developed. Here, a strong magnet fixed to one side of the vibration-arm along with a set of wires placed along the vibrating path will generate electricity. The circular device has a radius of 180 mm, a width of 50 mm, and weighs 200 grams. Because of its light mass, it is easy to carry and put into a backpack. Experimental results reveal that the energy harvester (prototype III) can easily transform kinetic energy into electrical power via the vibration-based electromagnetic system when walking at a normal speed. Consequently, electrical energy reaching 0.25 W is generated from the energy harvester (prototype III) by extracting kinetic energy produced by walking.

Note: A kinematic shaker system for high amplitude, low frequency vibration testing

2015 ◽  
Vol 86 (11) ◽  
pp. 116102 ◽  
Author(s):  
Anand Swaminathan ◽  
Matthew E. Poese ◽  
Robert W. M. Smith ◽  
Steven L. Garrett
Keyword(s):  
Low Frequency ◽  
High Amplitude ◽  
Vibration Testing ◽  
Low Frequency Vibration

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

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