Hz Vibration Research Articles

Acute Effects of Whole-Body Vibration on Trunk Muscle Functioning in Young Healthy Adults

The purpose of this study was to explore the immediate effects of different frequencies of whole-body vibration (WBV) on the performance of trunk muscles of healthy young adults. A group of 30 healthy subjects (15 men; 15 women; age, 26.8 ± 3.74 years; body mass index, 21.9 ± 1.802) participated in the study. Each subject received 3 sessions of vibration exercise with different exercise parameters with frequencies of 25 Hz and 40 Hz and sham stimulation in a random order on different days. Before and after each WBV exercise session, subjects were assessed for trunk muscle strength/endurance tests and trunk proprioception tests. There was a significant increase in trunk extensor strength (p ≤ 0.05) after low-frequency (25 Hz) WBV exercise, but high-frequency (40 Hz) vibration exercise had resulted in a significant decrease in trunk extensor endurance (p ≤ 0.05). Statistical gender difference (p = 0.04) was found for trunk extensor endurance with lower WBV training. No change was noted in the trunk proprioception with different frequencies of WBV. In conclusions, the immediate response of the body to WBV was different for low and high frequencies. Low-frequency vibration enhanced trunk extensor strength, but high-frequency vibration would decrease endurance of the trunk extensor muscles. Males are more sensitive than females in trunk extensor endurance for lower frequency WBV exposure. These results indicated that short-term WBV with low frequency was effective to improve trunk extensor strength in healthy adults, and that could be helpful for relevant activities of trunk extensor performing and preventing sport injury.

G-loading and vibration effects on heart and respiration rates.

Operational environments expose pilots and astronauts to sustained acceleration (G loading) and whole-body vibration, alone and in combination. Separately, the physiological effects of G loading and vibration have been well studied; both have effects similar to mild exercise. The few studies of combined G loading and vibration have not reported an interaction between these factors on physiological responses. We tested the effects of G loading (+1 and +3.8 G(x)) and vibration (0.5 gx at 8, 12, and 16 Hz), alone and in combination, on heart and respiration rate. We observed an effect of G loading on heart rate (average increase of 23 bpm, SD 12) and respiration rate (average increase of 5 breaths per minute, SD 5), an effect of vibration on heart rate, and an interaction on heart rate. With vibration, we observed heart rate increases of 4 bpm (SD: 3) with no increase in respiration rate. In the +1 G(x) condition, the largest heart rate increase occurred during low-frequency (8 Hz) vibration, while at +3.8 G(x), the largest heart rate increase occurred during high-frequency (16 Hz) vibration, demonstrating interaction. Consistent with previous reports, our G-loading and vibration effects are similar to mild exercise. In addition, we observed an interaction between G loading and vibration on heart rate, with maximum heart rates occurring at a higher vibration frequency at +3.8 G(x) compared to +1 G(x). The observed interaction demonstrates that G-loading and vibration effects are not independent and can only be properly assessed during combined exposure.

A Micro Inertial Energy Harvesting Platform With Self-Supplied Power Management Circuit for Autonomous Wireless Sensor Nodes

A 0.25 cm 3 autonomous energy harvesting micro-platform is realized to efficiently scavenge, rectify and store ambient vibration energy with batteryless cold start-up and zero sleep-mode power consumption. The fabricated compact system integrates a high-performance vacuum-packaged piezoelectric MEMS energy harvester with a power management IC and surface-mount components including an ultra-capacitor. The power management circuit incorporates a rectification stage with ~30 mV voltage drop, a bias-flip stage with a novel control system for increased harvesting efficiency, a trickle charger for permanent storage of harvested energy, and a low power supply-independent bias circuitry. The overall system weighs less than 0.6 grams, does not require a pre-charged battery, and has power consumption of 0.5 µW in active-mode and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$&lt; $</tex></formula> 10 pW in sleep-mode operation. While excited with 1 g vibration, the platform is tested to charge an initially depleted 70 mF ultra-capacitor to 1.85 V in 50 minutes (at 155 Hz vibration), and a 20 mF ultra-capacitor to 1.35 V in 7.5 min (at 419 Hz). The end-to-end rectification efficiency from the harvester to the ultra-capacitor is measured as 58–86%. The system can harvest from a minimum vibration level of 0.1 g.

The Effects of Whole-Body Vibration on the Wingate Test for Anaerobic Power When Applying Individualized Frequencies

Recently, individualized frequency (I-Freq) has been introduced with the notion that athletes may elicit a greater reflex response at differing levels (Hz) of vibration. The aim of the study was to evaluate acute whole-body vibration as a feasible intervention to increase power in trained cyclists and evaluate the efficacy of using I-Freq as an alternative to 30Hz, a common frequency seen in the literature. Twelve highly trained, competitive male cyclists (age, 29.9 ± 10.0 years; body height, 175.4 ± 7.8 cm; body mass, 77.3 ± 13.9 kg) participated in the study. A Wingate test for anaerobic power was administered on 3 occasions: following a control of no vibration, 30 Hz, or I-freq. Measures of peak power, average power (AP), and the rate of fatigue were recorded and compared with the vibration conditions using separate repeated measures analysis of variance. Peak power, AP, and the rate of fatigue were not significantly impacted by either the 30 Hz or I-Freq vibration interventions (p > 0.05). Given the trained status of the individuals in this study, the ability to elicit an acute response may have been muted. Future studies should further refine the vibration parameters used and assess changes in untrained or recreationally trained populations.

Direct Radial LMHF Microvibration Induced Bone Formation and Promoted Implant Osseointegration

Mechanical loading is known to play an important role in bone remodeling. This study aimed to evaluate the effect of direct low-magnitude high-frequency (LMHF) microvibration on dental implant bone formation and osseointegration. Titanium implants were installed in rabbit tibiae. The implants in the left legs were loaded with mechanical vibration (15 μm) at 10, 20, 30, and 40 Hz (10, 20, 30, and 40 Hz groups, respectively) for 30 minutes every day. The implants on the right legs were used as a sham control and did not receive a vibration load. After 20 days, the 10, 20, and 30 Hz groups showed significantly greater newly formed bone volume, density, ratio of the bone surface area to the trabecular bone surface area, and ratio of the bone surface area in direct contact with osteoclasts versus the total bone surface area in the region of interest compared with the sham control group, especially the 20 Hz group. However, the 40 Hz group did not. In conclusion, the application of direct LMHF (10, 20, or 30 Hz) vibration on the implants promoted bone formation and osseointegration, especially at 20 Hz; however, the use of 40 Hz did not result in any significant improvement.

Does acute side-alternating vibration exercise enhance ballistic upper-body power?

The aim of this study was to investigate the effects of acute vibration exercise, at 2 different frequencies, on upper body power output. Muscle activity (EMG) and upper-body peak power was measured in 12 healthy males during ballistic bench press throws at 30% of 1-repetition maximum on a Smith machine. Measures were made prior to, 30 s and 5 min after one of 3 conditions performed for 30 s in a press-up position: side-alternating vibration at 20 Hz, 26 Hz and no vibration. EMG was recorded in the anterior deltoid, triceps brachii and pectoralis major during ballistic bench press throws as well as during application of each condition. While peak power output was higher at 5 min post condition across all conditions, compared to baseline measures (P<0.05), only 20 Hz vibration resulted in a significant increase in peak power output (P<0.05) compared to no vibration. EMG was greater during both vibration conditions, compared to no vibration (P<0.001). However, this difference was not evident during bench press throws when no difference was seen in muscle activity between conditions. These findings suggest that 20 Hz vibration has an ergogenic effect on upper-body power that may be due to peripheral, rather than central, mediated mechanisms.

Do whole-body vibrations affect spatial hearing?

To assist the human operator, modern auditory interfaces increasingly rely on sound spatialisation to display auditory information and warning signals. However, we often operate in environments that apply vibrations to the whole body, e.g. when driving a vehicle. Here, we report three experiments investigating the effect of sinusoidal vibrations along the vertical axis on spatial hearing. The first was a free-field, narrow-band noise localisation experiment with 5- Hz vibration at 0.88 ms− 2. The other experiments used headphone-based sound lateralisation tasks. Experiment 2 investigated the effect of vibration frequency (4 vs. 8 Hz) at two different magnitudes (0.83 vs. 1.65 ms− 2) on a left–right discrimination one-interval forced-choice task. Experiment 3 assessed the effect on a two-interval forced-choice location discrimination task with respect to the central and two peripheral reference locations. In spite of the broad range of methods, none of the experiments show a reliable effect of whole-body vibrations on localisation performance.

Кислотно-гемолитическая устойчивость эритроцитов напряженного эритропоэза в условиях низкочастотной вибрации

Исследовано 14-дневное влияние вибрации с частотами 8, 16, 24 и 32 Гц, амплитудой 0,8±0,12 мм на кислотную резистентность эритроцитов мышей. Вибрация с частотами 8, 16 и 24 Гц вызывает напряженный эритропоэз. Высокая активность стресс-реализующих механизмов приводит к падению общего содержания эритроцитов в крови, снижению доли «старых», низкостойких эритроцитов и общему повышению их устойчивости к кислотному гемолизу. Вибрация с частотой 32 Гц блокирует эритропоэз, следствием чего является быстрое истощение резерва зрелых эритроцитов и снижение их кислотной устойчивости.

Effects of Local Vibration on Bone Loss in ­Tail-Suspended Rats

We investigated the effects of vibration (35 Hz, 45 Hz and 55 Hz) as countermeasure locally applied to unloading hind limbs on bone, muscle and Achilles tendon. 40 female Sprague Dawley rats were divided into 5 groups (n=8, each): tail-suspension (TS), TS plus 35 Hz/0.3 g vibration (TSV35), TS plus 45 Hz/0.3 g vibration (TSV45), TS plus 55 Hz/0.3 g vibration (TSV55) and control (CON). After 21 days, bone mineral density (BMD) and the microstructure of the femur and tibia were evaluated by μCT in vivo. The biomechanical properties of the femur and Achilles tendon were determined by a materials testing system. Ash weight of bone, isotonic contraction and wet weight of soleus were also investigated. 35 Hz and 45 Hz localized vibration were able to significantly ameliorate the decrease in trabecular BMD (expressed as the percentage change from TS, TSV35: 48.11%, TSV45: 31.09%), microstructure and ash weight of the femur and tibia induced by TS. Meanwhile, 35 Hz vibration significantly improved the biomechanical properties of the femur (57.24% bending rigidity and 41.66% Young's modulus vs. TS) and Achilles tendon (45.46% maximum load and 66.67% Young's modulus vs. TS). Additionally, Young's modulus of the femur was highly correlated with microstructural parameters. Localized vibration was useful for counteracting microgravity-induced musculoskeletal loss. In general, the efficacy of 35 Hz was better than 45 Hz or 55 Hz in tail-suspended rats.

Free Vibration Analysis of a Model Structure with New Tuned Cradle Mass Damper

Tuned cradle mass dampers (TCMDs) use the motion of a swing mass on a curved surface to dissipate structural vibration energy. In this study, we developed a TCMD that had a constant swing speed. We verify its performance by performing experiments and numerical analysis for a structure undergoing free vibrations. To obtain a device with a constant speed, variable radii of the curved surfaces were calculated using simple pendulum dynamics. In this study, the damper was installed in a simple one-story rigid-frame model with a frequency of approximately 1 Hz and free vibrations was excited. The numerical analysis results agreed well with the experimental results.

A non-resonant, frequency up-converted electromagnetic energy harvester from human-body-induced vibration for hand-held smart system applications

We present a non-resonant, frequency up-converted electromagnetic energy harvester that generates significant power from human-body-induced vibration, e.g., hand-shaking. Upon excitation, a freely movable non-magnetic ball within a cylinder periodically hits two magnets suspended on two helical compression springs located at either ends of the cylinder, allowing those to vibrate with higher frequencies. The device parameters have been designed based on the characteristics of human hand-shaking vibration. A prototype has been developed and tested both by vibration exciter (for non-resonance test) and by manual hand-shaking. The fabricated device generated 110 μW average power with 15.4 μW cm−3 average power density, while the energy harvester was mounted on a smart phone and was hand-shaken, indicating its ability in powering portable hand-held smart devices from low frequency (&amp;lt;5 Hz) vibrations.

Controller design and experimental investigation of a 3-universal-prismatic-universal compliant manipulator for active vibration isolation

For low frequency signals under 10 Hz, effective control methods are urgently needed to realize active vibration control for precision instruments. Based on our previous works on design and dynamical modeling of micro-parallel manipulators, a mixed control model is proposed for controlling a compliant three universal-prismatic-universal (3-UPU) parallel platform in this paper, which is established in a state-space framework considering the stiffness of flexure hinges. Moreover, other control methods in terms of LQR, H2 and are approached for a multiple-input and multiple-output (MIMO) active vibration isolation system, and the mixed method has proved more effective than the three methods mentioned above. Finally, an experimental system is built up to implement the active vibration control using an improved 3-UPU compliant parallel manipulator prototype. With the hardware and software developed, the real-time active vibration control methods have been tested at random signals; frequency rates at 0.5 Hz and 1 Hz are selected for illustrations. The experimental results demonstrate that the vibrations acting on the base and the moving platform are significantly reduced, and are limited to 0–10 Hz vibration signals. This active vibration control system provides a reliable experimental platform for validating the theoretical analysis work.

A Multiwell Disc Appliance Used to Deliver Quantifiable Accelerations and Shear Stresses at Sonic Frequencies

To mimic in vivo vibration of vocal fold cells, we studied the controllability and range of frequency, acceleration, duration, and shear stress in a new bioreactor attachment. The custom multiwell disc appliance fits into a commercially built rheometer, together termed a torsional rheometer bioreactor (TRB). Previous attachments to the TRB were capable of 50–100 Hz vibrations at relatively high strains but were limited to single-sample experiments. The TRB-multiwell disc system accommodates 20 samples in partially fluid-filled wells in an aseptic environment delivering three different acceleration conditions to different samples simultaneously. Frequency and amplitude used to calculate acceleration along with duration and shear stress were controllable and quantifiable using a combination of built-in rheometer sensors, manufacturer software, and smooth particle hydrodynamics (SPH) simulations. Computed shear stresses at the well bottom using SPH in two and three dimensions were verified with analytical approximations. Results demonstrate capabilities of the TRB-multiwell disc system that, when combined with computational modeling, provide quantifiable vibration parameters covering frequencies 0.01–250 Hz, accelerations of 0.02–300 m/s2, and shear stresses of 0.01–1.4 Pa. It is well-suited for studying cell function underlying vocal fold lamina propria homeostasis, inflammation, and wound healing under differential vibration conditions.

Free Vibration and Material Mechanical Properties Influence Based Frequency and Mode Shape Analysis of Transmission Gearbox Casing

The main objective of this research work is to study the effect of mechanical properties of materials on natural frequency and mode shapes of heavy vehicle gearbox transmission casing. Material mechanical properties play an important role for evaluation of frequency, deformation, stress and strain. Four materials have different density and the origin of material is also different. Grey cast iron has damping property, structural steel has high density and rigidity, Al and Mg alloys have low density. Free vibration study was performed for the vibration response study of casing. Grey cast iron grade FG 260, Structural Steel, Al alloy and Mg Alloy materials were analyzed on the design and vibration index. The free vibration study of casing was performed using finite element simulation. The vibration response for all materials shows the variation of natural frequency (1002-3879) Hz and various vibrations mode shapes. The vibration responses for first twenty modes were studied. Solid Edge and Pro-E was used for CAD designing of transmission gearbox casing. FEA based ANSYS 14.5 is used for modal analysis. Fixed- fixed constraint based boundary condition was used by constraining the connecting bolts hole. The transmission casing is tightly mounted on vehicle frame using connecting bolts. Loose transmission casing causes heavy noise and vibration problem. The simulation results were compared with experiment results available in literature.

A Novel Fiber Bragg Grating Accelerometer Based on Fiber Vibrating Wire

Abstract A fiber Bragg grating (FBG) accelerometer based on fiber vibrating wire is presented. Finite element analysis has been done and experiments are carried out to demonstrate the performance of this FBG accelerometer. The seismic simulation experimental results indicate that the system has a good response to the 50–400 Hz vibration signal. What more, the accelerometer has a high sensitivity which can reach 108.6 pm/G at 100Hz. The linear responsivity and repeatability are also tested. The responsivity error is less than 2.5% and repeatability error is less than 0.03%. There is an extremely linear relationship between amplitude of detected signal and acceleration.

To Compare the Effect of Vibration Therapy and Massage in Prevention of Delayed Onset Muscle Soreness (DOMS)

To compare the effects of vibration therapy and massage in prevention of DOMS. Pre-test and Post-test Control-Group Design was used, 45 healthy female non athletic Subjects were recruited and randomly distributed to the three groups (15 subject in each group). After the subject's initial status was measured experimental groups received vibration therapy (50 Hz vibration for five minutes) or massage therapy (15 minutes) intervention and control group received no treatment, just prior to the eccentric exercise. Subjects were undergoing the following measurements to evaluate the changes in the muscle condition: muscle soreness (pain perception), Range of Motion (ROM), Maximum Isometric Force (MIF), Repetition maximum (RM), Lactate dehydrogenase (LDH) and Cretain Kinase (CK) level. All the parameters except LDH, CK and 1RM were measured before, immediately post intervention, immediately post exercise, 24 hours post exercise, 48 hours post exercise and 72 hours post exercise. LDH, CK and 1 RM were measured before and 48 hours post exercise. Muscle soreness was reported to be significantly less for experimental (vibration and massage) group (p=0.000) as compared to control group at 24, 48, and 72 hours of post-exercise. Experimental and control group did not show any significant difference in MIF immediate (p=0.2898), 24 hours (p=0.4173), 48 hours (p=0.752) and 72 hours (p=0.5297) of post-exercise. Range of motion demonstrated significant recovery in experimental groups in 48 hours (p=0.0016) and 72 hours (p=0.0463). Massage therapy showed significant recovery in 1RM (p=0.000) compared to control group and vibration therapy shows significantly less LDH level (p=0.000) 48 hours of post exercise compare to control group. CK at 48 hours of post exercise in vibration group (p=0.000) and massage group showed (p=0.002) significant difference as compared to control group. Vibration therapy and massage are equally effective in prevention of DOMS. Massage is effective in restoration of concentric strength (1 RM). Yet vibration therapy shows clinically early reduction of pain and is effective in decreasing the level of LDH in 48 hours post exercise periods.

Effect of Vibration Frequency on Serratus Anterior Muscle Activity during Performance of the Push-up Plus with a Redcord Sling.

[Purpose] We investigated the effect of vibration at various frequencies on serratus anterior (SA) muscle activity. [Subjects] Ten male subjects were recruited. [Methods] The subjects performed the push-up plus exercise supported by straps above the surface and vertical ropes in the Redcord sling. During the push-up plus, vibrations of 0, 30, 50, or 90 Hz were applied to the Redcord sling using a mechanical vibration apparatus attached to the rope. SA muscle activity was recorded using electromyography. [Results] SA muscle activity at the 50 Hz vibration frequency was significantly higher than that of no vibration. [Conclusion] Performing the push-up plus using a Redcord sling with mechanical vibration of 50 Hz effectively increased SA muscle activity.

Force and thermal effects in vibration-assisted grinding

Because it reduces forces and temperatures, vibration-assisted grinding has the potential to improve the feasibility of dry grinding. This paper presents an experimental study of force and temperature effects in dry and wet grinding at vibration frequencies below ultrasonic. Based on a moving line heat source model, heat flux quantities were estimated from subsurface temperature measurements. Reductions in force of up to 30 % were observed for dry grinding with 2,360 Hz vibration assistance. For the same condition, heat flux into the workpiece reduced by 42 %. The paper presents evidence that vibration assistance has a beneficial effect on the convective heat transfer rate.

VIBRATION SENSOR BASED ON FLAT KOIL FOR EARTHQUAKE EARLY DETECTION IN LOMBOK NUSA TENGGARA BARAT REGION

In this research has been developed the application of flat coil as vibration sensor for early detection of earthquake. The flat coil is a very thin wire winding and acts as an inductor. This flat coil along with the capacitor constructs an oscillator which generates frequencies depending on the value of inductance and capacitance. This oscillator is called the LC oscillator. The flat coil inductance depends on the distance of the metal object in front of the flat coil. If the inductance changes, the frequency will change as well. Frequency can be converted into voltage form to represent distance. This effect is then applied to low frequencies using a pendulum on the sensor housing. The sensor system created can measure low-frequency vibrations in the range 0.26 - 1.0 Hz. Based on the research, the vibration sensor that has been made can measure one of the low frequency vibrations of 0.468 Hz at the frequency of 0.46 Hz vibration source

Development and experimental study of beryllium window for ITER radial X-ray camera

Radial X-ray camera (RXC) is a diagnostic device planned to be installed in the ITER Equatorial Port #12. Beryllium window will be installed between the inner and outer camera of RXC, which severs as the transmission photocathode substrate and also the vacuum isolation component. In this paper the design and manufacture process of two types of beryllium windows were introduced. Although 50μm thickness of beryllium foil is the best choice, the 80μm one with X-ray threshold of 1.34keV was selected for safety consideration. Using the intermediate layer (low purity of beryllium) between the beryllium foil and the stainless steel base flange is an effective strategy to limit the welding thermal deformation and thermal stress of the thin foil caused by bonding between different materials. By using ANSYS software, the feasibility of the aperture design was analyzed and validated. Metal sealing ring was applied in the mechanical clamped beryllium window for its good stability under high temperature and neutron radiation. Although both of the hollow metal sealing ring with 0.03mm silver coating and the pure silver sealing ring can satisfy the sealing requirement, the later one was chosen to produce the final product. Two hours 240°C high temperature baking test, two hours 3.3Hz vibration test and fatigue test were performed on the two types of beryllium windows. Based on the tests results, the two types of beryllium windows could stand the high temperature baking during the wall conditioning phase of ITER tokamak and the vibration during transportation without causing large leakage. Both of the two types of beryllium windows could bear impact load (0.1MPa pressure difference) for many times without failure.