Vibration Cycle Research Articles

Measurement of flow separation in a human vocal folds model

The paper provides experimental data on flow separation from a model of the human vocal folds. Data were measured on a four times scaled physical model, where one vocal fold was fixed and the other oscillated due to fluid–structure interaction. The vocal folds were fabricated from silicone rubber and placed on elastic support in the wall of a transparent wind tunnel. A PIV system was used to visualize the flow fields immediately downstream of the glottis and to measure the velocity fields. From the visualizations, the position of the flow separation point was evaluated using a semiautomatic procedure and plotted for different airflow velocities. The separation point position was quantified relative to the orifice width separately for the left and right vocal folds to account for flow asymmetry. The results indicate that the flow separation point remains close to the narrowest cross-section during most of the vocal fold vibration cycle, but moves significantly further downstream shortly prior to and after glottal closure.

Method For Calibrating A Backlash Impulse Device In A Sport Implement

The calibration of a backlash impulse device in a sport implement ( 20 ) is effected by firstly measuring the natural frequency of the striking surface ( 26 ) of the implement; determining from the measured natural frequency, a time of occurrence *T* and a duration of a period of elastic recovery *R′ of the striking surface ( 26 ) in a first vibration cycle *P* following an impact on the striking surface ( 26 ). The method also comprises the step of adjusting a distance of travel ‘D’ of the movable mass ( 32 ) inside the backlash impulse device during a strike of a ball with the sport implement ( 20 ), such that an impulse ( 62 ) is generated on the striking surface ( 26 ) by this movable mass ( 32 ) during the strike, at the same time as the occurrence of the period of elastic recovery ‘R’ of the striking surface, in the first vibration cycle ‘P’ following the strike.

用于精密定位平台的直线超声电机的异步并联

A concept of Asynchronous Bundle of Linear Ultrasonic Motor(ABLUSM) was proposed to improve the resolution,thrust and the speed of driving unit for a precision positioning stage.It points out that a numbers of stators(vibrators) alternately drive a mover(rotor) in a vibration cycle,the actual driving frequency is increased doubly,and better output performance can be expected.An analysis shows that increasing the contact frequency between stator and mover is able to improve the output force,speed and transient response characteristics of a Linear Ultrasonic Motor(LUSM).Meanwhile,it can avoid the mutual interference of different stators in Synchronous Bundling of LUSM(SBLUSM).Experimental results of two types of motors show that the maximum load force of the ABLUSM is 30% upon that of the SBLUSM or 25% over that of the sum of two motors when they drive the slider respectively.Results of minimum resolution test show that the minimum displacement resolution of the ABLUSM is 32.6 nm,which is 62.8% that of a single LUSM or 38.5% that of the SBLUSM.The mechanical characteristic experiments of the LUSM with one driving tip also prove that the no-load speed of ABLUSM has increased by 10% as compared with that both of the single stator and the SBLUSM.Moreover,the maximum efficiency has by 50% over that of the SBLUSM.Transient response time is shorter than SBLUSM,which is about 50% of a single stator.

A numerical approach on life-prediction of solder joints under combined loading for chip packaging system

The aim of this paper is to provide a numerical approach to predict the lifetime of solder joints by considering combined loading based on the damage superposition. The deformations of solder joints are calculated under vibration and thermal cycling loading respectively. The calculated results are defined as boundary conditions of the multi-axial loading. The strain/stress is investigated by finite element method based on the Chaboche model. The fatigue damage and creep damage are calculated by using the Manson-Coffin equation. It reveals that there is a strong non-linear impact on the lifetime due to the interaction of the combined loading. The trend of the simulation results basically agrees with that of the tests results. The approach can be used to predict the solder joint lifetime under combined loading.

Nonlinear Vibration Characteristics of a Flexible Blade with Friction Damping due to Tip-Rub

An approximate approach is proposed in this paper for analyzing the two-dimensional friction contact problem so as to compute the dynamic response of a structure constrained by friction interfaces due to tip-rub. The dynamical equation of motion for a rotational cantilever blade in a centrifugal force field is established. Flow-induced distributed periodic forces and the internal material damping in the blade are accounted for in the governing equation of motion. The Galerkin method is employed to obtain a three-degree-of-freedom oscillator with friction damping due to tip-rub. The combined motion of impact and friction due to tip-rub produced a piecewise linear vibration which is actually nonlinear. Thus, a complete vibration cycle is divided into successive intervals. The system possesses linear vibration characteristic during each of these intervals, which can be determined using analytical solution forms. Numerical simulation shows that the parameters such as gap of the tip and the rotational speed of the blades have significant effects on the dynamical responses of the system. Finally, the nonlinear vibration characteristics of the blade are investigated in terms of the Poincare graph, and the frequency spectrum of the responses and the amplitude-frequency curves.

Nonlinear Vibration Characteristics of a Flexible Blade with Friction Damping due to Tip-Rub

An approximate approach is proposed in this paper for analyzing the two-dimensional friction contact problem so as to compute the dynamic response of a structure constrained by friction interfaces due to tip-rub. The dynamical equation of motion for a rotational cantilever blade in a centrifugal fo rce field is established. Flow-induced distributed periodi c forces and the internal material damping in the blade are accounted for in the governing equation of motion. The Galerkin method is employed to obtain a three-degree-of-freedom oscillator with frict ion damping due to tip-rub. The combined motion of impact and friction due to tip-rub produced a piecewise linear vibration which is actually nonlinear. Thus, a complete vibration cycle is divided into successive intervals. The system possesses linear vibrati on characteristic during each of these intervals, which can be determined using analytical solution forms. Numerical simulation shows that the parameters such as gap of the tip and the rotational speed of the blades have significant effects on the dynamical respons es of the system. Finally, the nonlinear vibration characte ristics of the blade are investigated in terms of the Poincare graph, and the frequency spectrum of the responses and the amplitude-frequency curves.

Analysis of regenerative chatter suppression with adding the ultrasonic elliptical vibration on the cutting tool

A method is proposed to suppress regenerative chatter in turning operation, in which the ultrasonic elliptical vibration is added on the cutting tool. It results in the fact that the cutting tool is separated periodically from the chip and the workpiece, and the direction of the frictional force between the rake face of the cutting tool and the chip is reversed in each cycle of the ultrasonic elliptical vibration. The experimental investigations show that the regenerative chatter occurring in ordinary turning operation can be suppressed effectively by applying the ultrasonic elliptical vibration on the cutting tool. In order to clearify the reason of the regenerative chatter suppression, theoretical analysis and computer simulation are performed on turning with ultrasonic vibration. There is a good agreement among the experimental investigations, theoretical analysis and the computer simulation.

Effect of bimodularity on frequency response of cylindrical panels using Galerkin time domain approach

The forced vibration analysis of bimodulus material laminated structures is a challenging problem due to non-smooth nonlinear nature of governing equations. The most commonly used direct time integration schemes show numerical instability and do not predict steady state response except for limited number of cases without considering in-plane inertia. This is due to the sudden change of restoring force from positive/negative half cycle to negative/positive half cycle exciting higher modes/harmonics at every instant of a cycle change leading to numerical instability in the time marching scheme. In the present work, Galerkin time domain approach is successfully used for the forced vibration analysis of bimodular cylindrical panels. The effect of bimodularity ratio on the frequency response of cylindrical panels for few typical geometrical and lamination parameters is studied for the first time. It is found that the positive half cycle amplitude is greater than the negative half cycle amplitude for E 2t /E 2c < 1 and is smaller for E 2t /E 2c > 1. Further, the percentage difference of positive and negative half cycle amplitudes decreases with the increase in E 2t /E 2c . The stresses under dynamic loading are different for positive and negative half of a vibration cycle.

Stimulated Raman amplification and high-order Raman sideband generation in a polymer waveguide on a printed circuit

The ultrafast Raman response of C-H vibrations in polymer waveguides on a printed circuit is shown to enable a high-gain amplification and high-order stimulated Raman transformation of ultrashort laser pulses. The pump and Stokes fields coupled by the C-H vibration mode with a vibration cycle of 11 fs give rise to multiple Raman sidebands, suggesting the way toward ultrafast optical data processing and few-cycle optical waveform synthesis on a printed-circuit polymer waveguide platform.

Study on the Stress Field in Ultrasonic Grinding Engineering Ceramics

The mechanical model of stress field was established in grinding with/without ultrasonic vibration assistance, based on indentation fracture mechanics. Compared with the stress field in conventional grinding, the research has shown that the grinding stress field changes periodically with the vibration process of the moving grains in ultrasonic grinding. In a vibration cycle, the grains interfere with the workpiece within the time of T+Δt and cut off the material from the workpiece surface. Meantime, the large impact force between the grinding wheel and the workpiece results in stress field on the ground surface. In other period of vibration cycle, the grains are detached from the workpiece surface, and there exists no interaction between them. The grinding force disappears, so does the grinding stress field.

Self-Tuning Electrostatic Energy-Harvester IC

Miniature self-powered systems like wireless microsensors that rely only on easily exhaustible tiny in-package batteries suffer from short lifetimes. Harvesters, however, extend life by replenishing consumed energy with energy from the environment. The problem is harvesters generate considerably low power so producing a net gain with which to recharge a battery requires ultra low-energy circuits. This brief presents a 1.5 x1.5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 0.7-μm BiCMOS self-tuning electrostatic energy-harvester integrated circuit (IC) that adapts to changing battery voltages (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BAT</sub> ) to produce usable power from vibrations across V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BAT</sub> 's entire operating range. The prototype holds C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VAR</sub> 's voltage so that kinetic energy in vibrations can generate and steer current into the battery when capacitance decreases. Unlike in [13], the inductor-based precharger that charges C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VAR</sub> to V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BAT</sub> adapts to a constantly shifting V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BAT</sub> target. Collectively, the precharger and its self-tuning reference, system monitors, and other control circuits draw sufficient power to operate yet dissipate low enough energy to yield a net gain. Experimentally, the harvester IC generates 1.93, 2.43, and 3.89 nJ per vibration cycle at battery voltages 2.7, 3.5, and 4.2 V, which at 30 Hz produce 57.89, 73.02, and 116.55 nW. Accordingly, the system charges 1 μF from 2.7 to 4.2 V (a thin-film lithium-ion range) in 69 s and harnesses 47.9% more energy than with a fixed reference in the same time frame.

Fatigue Margins Established by Unit and Spacecraft Protoqualification Tests

Protoqualification (PQ) testing, typically performed on the first assembled electronic units and spacecraft, establish random vibration and thermal cycling fatigue margins for subsequent builds that are only subjected to the acceptance test program (ATP). Considering the fatigue damage induced by both unit- and spacecraft-level testing, fatigue margins are calculated for equipment exposed to ATP-level testing. Probabilistic analyses are also performed to determine the relationship between the fatigue margin and the demonstrated reliability for the unit to survive the mission. Parameters such as the number of retests and the material dependent fatigue acceleration exponent are considered. Using MIL-STD-1540E,1 PQ random vibration test guidelines of three decibels (+3 dB) above the acceptance input level for 2-minute-per-axis duration, the assessment shows that the test establishes ample fatigue margin for units subjected to the less stringent ATP. The probabilistic analysis shows that the established reliability to survive the launch environment without a fatigue induced failure is adequate. It is further shown that the desired high-cycle fatigue life factor of greater than four is maintained even after one unit retest is performed. However, since this conclusion is general in nature, it is important that for future spacecraft, assessments be performed for both PQ and ATP hardware, taking into account each specific design and application to verify that adequate fatigue margin exists to survive launch. Because mission thermal cyclic environments vary greatly with regard to the number of cycles and the extent of the thermal range for each cycle, MIL-STD-1540E PQ guidelines for unit-level testing were designed to verify the design and workmanship and not intended to demonstrate fatigue margin for specific missions. Rather, MIL-STD-1540E specifies that thermal cyclic fatigue margin for the combination of pre-launch and orbital environments should be demonstrated with life testing. Accordingly, the analysis shows that PQ testing only demonstrates the desired low-cycle fatigue life factor of 2 for subsequent units which are subjected to a single ATP. The fatigue life factor falls below 2 when retests and/or mission thermal cyclic environments are considered. Because acceptable fatigue margin is not established with the standard PQ thermal cycle test procedure, it is essential that other means be taken to ensure that adequate fatigue margin exists. This paper provides guidelines for using analyses and offline life testing to assess the fatigue life of critical units and their internal components for pre-launch and orbital thermal cyclic environments.

VFIFE METHOD APPLIED FOR OFFSHORE TEMPLATE STRUCTURES UPGRADED WITH DAMPER SYSTEM

In this study, a plane frame element derived from vector form intrinsic finite element (VFIFE) method is adapted and applied to study the dynamic responses of an offshore template platform subject to wave forces. Furthermore, this vector form intrinsic finite element is modified in order to incorporate a visco-elastic material, which has excellent energyabsorption ability, to a damping device installed in the structural system to mitigate the wave-induced vibration. The method adopted in this study is a scheme similar to the one by updating the geometry of the structural system during the calculation of each time step, which is also called the coordinate moving frame approach. It is found from the analytical results that an offshore template structure enhanced with VE damper has better performance on its dynamic responses., The mitigation on the response amplitude is significant and the resonant vibration coinciding to the fundamental frequency of the structural system can be mitigated into a very small value after a few cycles of vibration.

모의수송 중 진동피로에 의한 복숭아의 손상

Post-Harvest processing engineering is a field that studies prevention of the quality change of agricultural products during sorting, packaging, storage, and distribution after harvested. In distribution steps, agricultural products could be damaged by physical force, it is the main reason of low quality and they lost value of commodities. This study was performed to find the vibration characteristics of the peach, and to find the extent of the damage on the peach by fatigue stress. The vibration data was obtained on expressway and the vibration characteristics of peach was used to find the damage on the peach. To analyze the vibration characteristics of peach, the resonance frequency and vibration transmissibility were measured. The resonance frequency of the peach was 167.98 Hz and the transmissibility was 4.06 at resonance point. It was 150 ~ 250 Hz that the transmissibility was more than 1. And the transmissibility in simulated test was measured. When the trasmissibility was more than 1, the range was 15 ~ 65 Hz, and when it was less than 1, the range was 65 ~ 175 Hz. When the transmissibility was about 1, the range was 5 ~ 15 Hz. The damage and the vibration cycle numbers of peaches were compared with input frequency and acceleration. More damage and less cycle number happened in 30 Hz than in 62.5 Hz. The reason was that the transmissibility of 30 Hz was higher and the vibration displacement in lower frequency was more. The more acceleration and cycle number increased, the more the bruising volume of peaches increased. The bruising volume ratio for vibration fatigue was measured according to input acceleration and cycle number. Using measured data, regression models for bruising volume ratio(BVR) was developed as a function of the acceleration(A) and cycle number(CN) as follows. BVR = a * <TEX>$A^b*$</TEX> <TEX>$(CN)^c$</TEX>

Conduction degradation by fretting corrosion phenomena for contact samples made of high-copper alloys

The main cause of electrical contact resistance degradation by corrosion is the vibration of contact interfaces. The purpose of this paper is to analyse the change of contact resistance by means of a vibration test for uncoated sphere/plane contact made of new high-copper alloys. The influence of electrical and mechanical properties of materials, and mainly hardness, on contact resistance has been studied in this work. During the fretting test, a contact point was submitted to 16,000 vibration cycles under fretting amplitude of 50 μm and 1 Hz frequency. The sphere part was fixed, while the plane part was submitted to relative motion. At the end of the test, the fretted surfaces and the wear debris were analyzed by scanning electron microscope and energy dispersive X-ray spectroscopy to evaluate damage, oxidation and elemental composition present in the wear surfaces. In addition, the measurement of the wear track profile using a 3D surface scanning system was introduced. Increases in contact resistance and contact temperature were examined during the fretting test. The results showed that the contact resistance for the harder alloy was higher than that obtained for the other materials. In addition, topographic measurements showed that the small wear track corresponds to the harder material.

Vibration Phase‐Based Ordering of Vibration Patterns Acquired With a Shearing Speckle Interferometer and Pulsed Illumination

Abstract: A method for both temporal and spatial characterisation of harmonic vibrations is presented. The method is based on simultaneous acquisition of phase‐stepped speckle interference patterns using a shearing speckle interferometer and the vibration phase for a series of vibration states within the vibration period. An unsynchronised free‐running pulse laser is used for illuminating a vibrating object yielding speckle interference patterns in random vibration phase order. Two π/2 phase‐stepped speckle interference patterns are acquired simultaneously for each recorded vibration state. The data set is sorted using vibration phase as the sorting key. The sorted speckle interference patterns are processed using a two‐bucket algorithm for the calculation of phase difference and by applying temporal phase unwrapping to finally obtain unwrapped phase distributions for any vibration state of the vibration cycle.

Mechanical durability and electrical durability of an aluminium-laminated lithium-ion polymer battery pack for a hybrid electric vehicle

Lithium-ion polymer batteries of aluminium-laminated packaging structure have advantages in terms of thermal characteristics and safety but have a weak configuration with respect to external forces compared with other types of cells such as cylindrical and prismatic cells. Thus it is important to protect the batteries of the aluminium-laminated packaging structure under the severe conditions encountered in vehicle operation where excessive mechanical impacts and vibrations may affect the battery system. In this work, an energy storage system for a hybrid electric vehicle (HEV) has been developed using lithium-ion polymer battery cells with an aluminium-laminated packaging structure and has been tested for structural and electrical durabilities. The test results of combined accelerated vibration and charge discharge cycling are presented to prove that the battery pack has the durability to satisfy vehicle standards. Three different types of test method have been applied to evaluate the mechanical and electrical durabilities. It was observed that the HEV battery pack satisfied the durability standards required for vehicle applications. The results imply that an aluminium-laminated cell packaging structure can be a competitive option for physical configuration of cells for vehicle applications.

A 0.7-$\mu$m BiCMOS Electrostatic Energy-Harvesting System IC

Self-powered microsystems like wireless microsensors and biomedical implants derive power from in-package minibatteries that can only store sufficient energy to sustain the system for a short life. The environment, however, is a rich source of energy that, when harnessed, can replenish the otherwise exhausted battery. The problem is harvesters generate low power levels and the electronics required to transfer the energy to charge a battery can easily demand more than the power produced. This paper presents how a 1 × 1 mm2 0.7-μm BiCMOS vibration-supplied electrostatic energy-harvesting system IC produces usable energy. The IC charges and holds the voltage across a vibration-driven variable capacitor CVAR so that ambient kinetic energy can induce CVAR to generate current into the battery when capacitance decreases, as the plates separate. The precharger, harvester, monitoring, and control microelectronics draw enough power to operate, yet allow the system to yield (experimentally) 1.27, 2.14, and 2.87 nJ per vibration cycle for battery voltages at 2.7, 3.5, and 4.2 V, which at 30 Hz produce 38.1, 64.2, and 86.1 nW. Experiments further show that the harvester system prototype charges 1 μF (emulating a small thin-film Li Ion) from 3.5 to 3.81 V in 35 s.

Effect of ultrasonic capillary dynamics on the mechanics of thermosonic ball bonding

Microelectronic wire bonding is an essential step in today's microchip production. It is used to weld (bond) microwires to metallized pads of integrated circuits using ultrasound with hundreds of thousands of vibration cycles. Thermosonic ball bonding is the most popular variant of the wire bonding process and frequently investigated using finite element (FE) models that simplify the ultrasonic dynamics of the process with static or quasistatic boundary conditions. In this study, the ultrasonic dynamics of the bonding tool (capillary), made from Al(2)O(3), is included in a FE model. For more accuracy of the FE model, the main material parameters are measured. The density of the capillary was measured to be rho(cap) = 3552 +/- 100 kg/m(3). The elastic modulus of the capillary, E(cap) = 389 +/- 11 GPa, is found by comparing an auxiliary FE model of the free vibrating capillary with measured values. A capillary "nodding effect" is identified and found to be essential when describing the ultrasonic vibration shape. A main FE model builds on these results and adds bonded ball, pad, chip, and die attach components. There is excellent agreement between the main model and the ultrasonic force measured at the interface on a test chip with stress microsensors. Bonded ball and underpad stress results are reported. When adjusted to the same ultrasonic force, a simplified model without ultrasonic dynamics and with an infinitely stiff capillary tip is substantially off target by -40% for the maximum underpad stress. The compliance of the capillary causes a substantial inclination effect at the bonding interface between wire and pad. This oscillating inclination effect massively influences the stress fields under the pad and is studied in more detail. For more accurate results, it is therefore recommended to include ultrasonic dynamics of the bonding tool in mechanical FE models of wire bonding.

Effects of Structural Perturbations on Strain Growth in Containment Vessels

Strain growth is a phenomenon observed in the elastic response of containment vessels subjected to internal blast loading. The local dynamic response of a containment vessel may become larger in a later stage than its response in the initial breathing mode response stage. It has been reported in our previous study that bending modes may be excited after several cycles of breathing mode vibration, due to the dynamic instability in cylindrical and spherical shells without structural perturbations. The nonlinear modal coupling between the breathing mode and the excited bending mode is one of the causes for the strain growth observed in containment vessels. In this study, we demonstrate that, due to the existence of structural perturbations, various vibration modes may be excited in containment vessels in earlier response stage before the occurrence of nonlinear modal coupling. The linear superposition of the breathing mode and the vibration modes excited by structural perturbations may cause larger response than the pure breathing mode response, which is a different strain growth mechanism from the nonlinear modal coupling. In the later response stage when the nonlinear modal coupling happens, not only the breathing mode, but also the vibration modes excited by structural perturbations will interact nonlinearly with the bending modes excited by dynamic unstable vibration. Dynamic nonlinear finite element program, LS-DYNA, is employed to understand the effects of structural perturbations on strain growth in containment vessels subjected to internal blast loading.