scholarly journals Characterizing vibration responses of a handheld workpiece and the hand–arm system

2020 ◽  
pp. 146134842093461
Author(s):  
Xueyan S Xu ◽  
Daniel E Welcome ◽  
Thomas W McDowell ◽  
Christopher Warren ◽  
Hansheng Lin ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Resonance Frequency ◽  
Grinding Wheel ◽  
Vibration Exposure ◽  
Apparent Mass ◽  
Entire System ◽  
Interface Conditions ◽  
Feed Force ◽  
Vibration Transmissibility ◽  
Vibration Responses

The objective of this study is to characterize the vibration responses of a handheld workpiece and the hand–arm system, which is an important step toward identifying and developing effective methods and technologies for controlling the vibration exposures to workers performing the grinding of handheld workpieces. This study established a method for measuring the vibration responses of the entire workpiece–hand–arm system; the vibration exposure of a worker holding and pressing a typical workpiece against a sanding belt or grinding wheel in order to shape the workpiece was simulated. This method was applied to measure the apparent mass and vibration transmissibility of the system under two different feed forces (15 N and 30 N) and six simulated grinding interfaces with different stiffness values. A major resonance was observed in each transmissibility spectrum of the workpiece, which was correlated with the major resonance of the impedance of the entire system. This resonant frequency depended primarily on the workpiece mass and the grinding interface stiffness, but the hand–arm system could substantially affect the resonance magnitude. The feed force also significantly affected the resonance frequency and magnitude. While increasing the feed force increased the overall vibration transmissibility on the hand–arm system, the transmissibility with respect to the workpiece was not significantly affected by the interface conditions. The implications of the results are discussed.

scholarly journals Vibration transmissibility and apparent mass changes from vertical whole-body vibration exposure during stationary and propelled walking

2021 ◽  
Vol 90 ◽  
pp. 103283
Author(s):  
Delphine Chadefaux ◽  
Alex P. Moorhead ◽  
Pietro Marzaroli ◽  
Stefano Marelli ◽  
Enrico Marchetti ◽  
...  
Keyword(s):  
Whole Body Vibration ◽  
Whole Body ◽  
Vibration Exposure ◽  
Apparent Mass ◽  
Body Vibration ◽  
Vibration Transmissibility

A comparison of the dynamic properties of transducer adapters for measurement of hand-transmitted vibration

2009 ◽  
Vol 223 (2) ◽  
pp. 345-351 ◽  
Author(s):  
C M Song ◽  
H-K Jang ◽  
J Chai
Keyword(s):  
Dynamic Characteristics ◽  
Grip Force ◽  
Dynamic Properties ◽  
Vibration Exposure ◽  
Frequency Range ◽  
Second Best ◽  
Best Estimate ◽  
Feed Force ◽  
Vibration Transmissibility ◽  
Exposure Levels

The dynamic characteristics of five types of widely used transducer adapters were compared in terms of vibration transmissibility between an accelerometer on the surface of the gripping area and another within each of the transducer adapters over a frequency range of 25–1250 Hz. Performance was also assessed from the ratio between two human vibration exposure levels, ahv, 1 and ahv, 2, measured using the two accelerometers over nine combinations of grip force and feed force. In this study, vibration transmissibility and ahv ratio of unity are considered. The vibration transmissibility and ahv ratio indicated that the flexible palm adapter provided the best estimate of vibration transmission to the hand. This transducer adapter exhibited the smallest deviation from unity for vibration transmissibility, which was <1.8 per cent over the frequency range, and ahv ratio, which was <4 per cent over nine combinations of grip and feed forces. From the investigation, the flexible palm adapter showed negligible distortion over the frequency range and high applicability, regardless of the gripping condition. The handle-type adapter provided the second-best estimate.

scholarly journals Vibration Exposure and Transmissibility on Dentist’s Anatomy: A Study of Micro Motors and Air-Turbines

2021 ◽  
Vol 18 (8) ◽  
pp. 4084
Author(s):  
Harish Kumar Banga ◽  
Pankaj Goel ◽  
Raman Kumar ◽  
Vikas Kumar ◽  
Parveen Kalra ◽  
...  
Keyword(s):  
Research Work ◽  
High Amplitude ◽  
Vibration Exposure ◽  
Body Parts ◽  
Descriptive Research ◽  
Air Turbine ◽  
Test Of Homogeneity ◽  
Hand Piece ◽  
Vibration Transmissibility ◽  
Levene Test

The use of dental hand pieces endanger dentists to vibration exposure as they are subjected to very high amplitude and vibration frequency. This paper has envisaged a comparative analysis of vibration amplitudes and transmissibility during idling and drilling with micro motor (MM) and air-turbine (AT) hand pieces. The study aims to identify the mean difference in vibration amplitudes during idling, explore different grasp forces while drilling with irrigant injection by the dentist, and various vibration transmission of these hand pieces. The study utilized 22 separate frequency resonances on two new and eight used MMs and two new and eight used ATs of different brands by observing the investigator at 16 different dentist clinics. The study adopted a descriptive research design with non–probability sampling techniques for selecting dentists and hand pieces. Statistical methods like Levene Test of Homogeneity, Welch ANOVA, independent t-test, and Games–Howell test were utilized with SPSS version 22 and MS-Excel. The results reveal that vibration amplitudes and vibration transmissibility when measured at position 2 are higher than in another position 1. Vibrations during idling for used MMs are more than AT hand pieces, and the used MM (MUD) and used AT (AUA) hand pieces differ due to their obsolescence and over-usage. Vibration amplitudes increase every time with the tightening of grasping of the hand piece. Vibration amplitudes for each grasping style of MM hand piece differ from all other grasping styles of AT hand pieces. Routine exposure to consistent vibrations has ill physical, mental, and psychological effects on dentists. The used hand pieces more hazardous as compared to newer ones. The study suggests that these hand pieces must be replaced periodically, sufficient to break between two operations, especially after every hand piece usage. Hence, the present research work can be further extended by creating some control groups among dentists and then studying the vibration amplitude exposure of various dental hand pieces and subsequent transmissibility to their body parts.

scholarly journals Design Optimization of MEMS Based LLC Tunable Resonant Converter for Power Supplies on Chip

2013 ◽  
Vol 705 ◽  
pp. 258-263
Author(s):  
Fahimullah Khan ◽  
Yong Zhu ◽  
Jun Wei Lu ◽  
Dzung Dao
Keyword(s):  
Resonant Frequency ◽  
Resonance Frequency ◽  
Parallel Plate ◽  
Power Supplies ◽  
Resonant Converter ◽  
Load Variations ◽  
Leakage Inductance ◽  
Variable Capacitor ◽  
Numerical Software ◽  
On Chip

In this paper, a novel MEMS based LLC converter is proposed for on chip power supplies. The design is optimized based on commercially available Metal MUMPs process for fabrication. The resonant frequency is optimized at 20MHz and MEMS based variable capacitor is fabricated on the chip to tune the peak resonance frequency of circuit which varies due to the load variations. The Design is simulated in FEM based numerical software COMSOL and Intellisuite. According to analysis the magnetizing inductance of 42nH and leakage inductance of 40nH has been achieved from 16 mm2 rectangular coil transformer. The total capacitance of 1500pF has been achieved from parallel plate capacitors and variation of 3pF has been achieved from variable capacitor.

Theoretical and experimental studies of a novel nested oscillator with a high-damping characteristic

2020 ◽  
pp. 107754632094378
Author(s):  
Haiping Liu ◽  
Kaili Xiao ◽  
PengPeng Zhao ◽  
Dongmei Zhu
Keyword(s):  
Resonant Frequency ◽  
Vibration Suppression ◽  
Damping Ratio ◽  
Experimental Studies ◽  
Harmonic Balance Method ◽  
Design Parameters ◽  
Base Excitation ◽  
Oscillation System ◽  
Equivalent Damping ◽  
Vibration Transmissibility

Stiffness and damping of a structure usually show the opposite change so that the resonant frequency and the static load bearing capacity of a mechanical system often exhibit contradiction. To solve this dilemma, a novel high-damping oscillator which is constructed by a nested diamond structure with the purpose of enhancing the damping property is proposed in this study without reducing the overall systematic stiffness. The mathematical model and geometrical relationships are established at first. And then, the steady-state solutions under base excitation are derived by using the harmonic balance method and further verified by numerical simulation. In addition, the effects of some design parameters on the equivalent damping ratio for the high-damping oscillator are studied to reveal the nonlinear characteristic. Besides, the natural frequency of the nonlinear oscillator is also presented and investigated. By using the displacement transmissibility and comparing with the traditional linear isolator with the same overall stiffness, the vibration suppression performance of the high-damping oscillator is addressed. The obtained calculating results demonstrate that the vibration control performance of the high-damping oscillator outperforms the linear counterpart around resonant frequency. Moreover, the influences of systematic parameters of the high-damping oscillator for the base excitation case on the vibration transmissibility are also discussed, respectively. Finally, an experimental campaign is conducted on an in-house-built test rig to corroborate the accuracy of the analytical solutions of the high-damping oscillation system. The results discussed in this study provide a useful guideline, which can help to design this class of high-damping oscillation system.

On the theory of plasma–sheath resonance in a non-uniform plasma

1999 ◽  
Vol 61 (3) ◽  
pp. 469-488 ◽  
Author(s):  
NOBORU TANIZUKA ◽  
JOHN E. ALLEN
Keyword(s):  
Resonant Frequency ◽  
Plasma Frequency ◽  
Inhomogeneous Plasma ◽  
Plasma Sheath ◽  
Entire System ◽  
Local Resonance ◽  
Uniform Plasma

Calculations are presented on the phenomenon of plasma–sheath resonance in an inhomogeneous plasma. In certain cases, this resonance coincides with a local resonance occurring in the plasma, the local plasma frequency being equal to the resonant frequency of the entire system. The theory does not describe the mechanism of absorption, but does predict the magnitude of the power involved. Some limitations of the theory are discussed.

scholarly journals Rancang Bangun Antena Mikrostrip Bowtie Pada Frekuensi 5,2 Ghz

2018 ◽  
Vol 10 (2) ◽  
pp. 15-21
Author(s):  
Aprinal Adila Asril ◽  
Lifwarda Lifwarda ◽  
Yul Antonisfia
Keyword(s):  
Dielectric Constant ◽  
Resonant Frequency ◽  
Resonance Frequency ◽  
Radiation Pattern ◽  
Microstrip Antenna ◽  
Return Loss ◽  
Microstrip Antennas ◽  
Antenna Design ◽  
Narrow Bandwidth ◽  
Simple Materials

Microstrip antennas are very concerned shapes and sizes. Can be viewed in terms of simple materials, shapes, sizes and dimensions smaller antennae, the price of production is cheaper and able to provide a reasonably good performance, in addition to having many advantages, the microstrip antenna also has its drawbacks one of which is a narrow bandwidth. In this research will be designed a microstrip antenna bowtie which works at a frequency of 5.2 GHz which has a size of 68mm x 33mm groundplane. For the length and width of 33mm x 13mm patch. This antenna is designed on a printed cicuit board (PCB) FR4 epoxy with a dielectric constant of 4.7 and has a thickness of 1,6mm. This bowtie microstrip antenna design using IE3D software. This antenna has been simulated using IE3D software showed its resonance frequency is 5.270 GHz with a return loss -23 595 dB bandwidth of 230 MHz, VSWR 1,142, unidirectional radiation pattern and impedance 43,919Ω. The results of which have been successfully fabricated antenna with a resonant frequency of 5.21 GHz with a return loss -16.813 dB bandwidth of 79 MHz, VSWR 1.368, unidirectional radiation pattern, impedance 43,546Ω and HPBW 105 °.

Analysis and Experiment of an Air Vibration Isolation System with Auxiliary Chambers

2012 ◽  
Vol 226-228 ◽  
pp. 195-198
Author(s):  
Rong Wei Wen ◽  
Jiu Bin Tan ◽  
Lei Wang ◽  
Guan Hua Wang
Keyword(s):  
Resonant Frequency ◽  
Vibration Isolation ◽  
Excitation Frequency ◽  
Volume Ratio ◽  
Air Spring ◽  
Working Pressure ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Vibration Transmissibility ◽  
System Vibration

A mathematical model of a single degree of freedom air spring vibration isolation system is established. The model analyzes the influence of structural damping in the air spring vibration isolation system based on the traditional model. This paper establishes the relationship between the working pressure p, the volume ratio of n and system vibration transmissibility T under forced vibration. The experimental results are verified on different working pressure. The results showed that working pressure p has little effect on the resonant frequency of the system and the system vibration transmissibility. The smaller the ratio n, the lower the resonant frequency of the system and the system vibration transmissibility. The environmental excitation frequency range must be taken into account in designing.

Subjective Response to Whole-Body Vibration

1982 ◽  
Vol 1 (3) ◽  
pp. 109-122
Author(s):  
Richard W. Shoenberger
Keyword(s):  
Resonance Frequency ◽  
Magnitude Estimation ◽  
Whole Body Vibration ◽  
Alternative Methods ◽  
Whole Body ◽  
Vibration Exposure ◽  
Subjective Response ◽  
Frequency Range ◽  
Body Vibration ◽  
Subjective Intensity

Pioneer studies of subjective response to whole-body vibration were mainly directed toward construction of equal intensity contours, described by such subjective labels as “intolerable,” “alarming,” or “annoying.” In a series of more recent investigations, carried out at AFAMRL, psychophysical measurement and scaling techniques have been adapted for use in whole-body vibration experiments, primarily to evaluate the intensive dimension of various types of vibration environments. A program of research is described in which the methods of magnitude estimation and intensity matching have been used to construct a family of Z-axis equal intensity curves in the whole-body resonance frequency range; investigate subjective response for frequencies below 1 Hz; evaluate alternative methods for assessing the severity of multifrequency and random vibrations; and compare the subjective intensity of vibrations in various translational and angular modes. Results from these experiments have contributed to the expansion and improvement of whole-body vibration exposure criteria.

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