Orbital Vibration Research Articles

Диагностика вибрационного состояния роторов двухконтурного турбореактивного двигателя с применением фазочастотной характеристики, полученной без использования датчика положения вала

This paper considers theoretical and practical approaches to the construction of amplitude-frequency phase characteristics of turbofan engines and presents the results of the experiments. The novelty lies in excluding usage of information from the sensor of its initial position for the construction of the rotor phase characteristic. To determine the instantaneous value of the phase angle of the rotor oscillations, the method of orbital vibration analysis is used. Using the analysis of phase change of rotor fluctuation allows to define availability of resonance as well as defects and malfunctions that cause induce stiffness and damping of the rotor. Examples of turbofan engines diagnostics by means of the analysis of amplitude-frequency phase characteristics are given.

Factors influencing the performance of cement emulsified asphalt mortar – A review

Cement emulsified asphalt mortar (CEAM) is an essential component in the ballastless slab track system. It is a semi-rigid composite material consisting mainly of hardened cement paste and demulsification asphalt, possessing the advantages of both ordinary Portland cement and asphalt. Its primary functions include: supporting structures, adjusting the slab track's geometry during construction, and dissipating/reducing orbital vibration. In this review, the preparation technology of CEAM was introduced at first. Subsequently, the hardening mechanism between asphalt emulsion and cement in CEAM was summarized. Meanwhile, the influence of asphalt emulsion type and dosage, sand to cement ratio (S/C), water to cement ratio (W/C), common auxiliary additives, and temperature on the properties of CEAM were compared and analyzed. This current review concludes that the most significant influence on CEAM performance is the mass ratio of asphalt to cement. With the increase of asphalt content, hardened cement asphalt paste (CA paste) would show two different overall mechanical properties. Besides, the effects of the S/C ratio and W/C ratio on high strength CEAM are not the same as that of low strength CEAM. Future research is recommended: to develop sustainable CEAM without prejudice to the performance; and to further analyze the interaction mechanism between emulsified asphalt and cement materials from the microscopic perspective.

Dynamic response analysis on vibration of ground and track system induced by metro operation

PurposeThis paper aims to evaluate the dynamic response of surrounding foundation and study the vibration characteristics of track system.Design/methodology/approachA double-line underground coupling analysis model was established, which included two moving train, track, liner and the ground field.FindingsBased on the 2.5D (D is diameter) finite element analysis, the influence of the important factors such as the depth of the subway tunnel, the nature of the foundation soil, the relative position relation of the double tunnel, the subway driving speed on the foundation and the orbital vibration are analyzed in this article.Originality/valueThe results in paper may have reference value for the prediction of train induced vibrations and for the research of dynamic response of ground field.

Whole body vibration and blood glucose levels in elderly people: a pilot study

***Whole body vibration and blood glucose levels in elderly people: a pilot study***AIMS: To evaluate the effect of whole-body vibration therapy on blood glucose levels of elderly people using a vibratory platform.METHODS: The study included volunteers of both genders, aged between 60 and 75 years, without gait disorders or motor disabilities. Individuals with systemic disease, obesity, conflicting treatments, tobacco users, and those who could not understand the maneuvers were excluded. The study consisted of a single session of whole-body vibration. Heart rate, respiratory rate, arterial blood pressure, and blood glucose were obtained for each participant at baseline, immediately before the procedure. Volunteers were then placed in the standing position on the ground of an oscillating platform and treated for 10 min with a frequency of vibration set at 20 Hz (displacement ±6 mm; orbital vibration). Immediately after the whole-body vibration session, all data were collected again. Comparisons were made between baseline and post-treatment data. Normality was tested by Kolmogorov-Smirnov test. Data were analyzed using paired Student’s t-test or Wilcoxon test as appropriate. The level of significance was set at p<0.05.RESULTS: Eleven participants (seven men, four women) participated of the study. The mean age was 64.18±4.37 years. The results showed a significant decrease in the glycemic indexes (p=0.016) and an increase in the respiratory rate (p=0.047) after the whole-body vibration session.CONCLUSIONS: Healthy elderly subjected for 10 minutes to whole-body vibration set at 20 Hz presented reduction of blood glucose levels and increasing of respiratory rate.

Whole body vibration and blood glucose levels in elderly people: a pilot study

***Whole body vibration and blood glucose levels in elderly people: a pilot study***AIMS: To evaluate the effect of whole-body vibration therapy on blood glucose levels of elderly people using a vibratory platform.METHODS: The study included volunteers of both genders, aged between 60 and 75 years, without gait disorders or motor disabilities. Individuals with systemic disease, obesity, conflicting treatments, tobacco users, and those who could not understand the maneuvers were excluded. The study consisted of a single session of whole-body vibration. Heart rate, respiratory rate, arterial blood pressure, and blood glucose were obtained for each participant at baseline, immediately before the procedure. Volunteers were then placed in the standing position on the ground of an oscillating platform and treated for 10 min with a frequency of vibration set at 20 Hz (displacement ±6 mm; orbital vibration). Immediately after the whole-body vibration session, all data were collected again. Comparisons were made between baseline and post-treatment data. Normality was tested by Kolmogorov-Smirnov test. Data were analyzed using paired Student’s t-test or Wilcoxon test as appropriate. The level of significance was set at p<0.05.RESULTS: Eleven participants (seven men, four women) participated of the study. The mean age was 64.18±4.37 years. The results showed a significant decrease in the glycemic indexes (p=0.016) and an increase in the respiratory rate (p=0.047) after the whole-body vibration session.CONCLUSIONS: Healthy elderly subjected for 10 minutes to whole-body vibration set at 20 Hz presented reduction of blood glucose levels and increasing of respiratory rate.

Acute effects of whole body vibration on heart rate variability in elderly people

BackgroundWhole body vibration (WBV) has been widely used as a modality for physical activity. In fact, WBV has been used for physical rehabilitation, and to improve muscle performance; but there is little information about its effects on heart rate variability (HRV). AimThe aim of this study was to evaluate the effect of vibration on HRV of the elderly using the vibratory platform. MethodsEleven older adults (7 men, 4 women), aged between 60 and 75 years, were subjected to WBV. The study consisted of a single session of WBV with volunteers standing upright for 10 min on the oscillating platform, with frequency of vibration set at 20 Hz (displacement ± 6 mm; orbital vibration). Pre (baseline) and post-WBV electrocardiograph signals were acquired using a cardiac monitor; and data were statistically analyzed using paired Student's t-test or Wilcoxon test, as appropriate. ResultsThe results demonstrated an increase in SDNN (standard deviation (SD) beat-to-beat, N–N intervals), rMSSD (square root of the mean squared difference of successive N–Ns) and pNN50 (proportion of N–N50 divided by total number of N–Ns) post WBV (p = 0.032, p = 0.024 e p = 0.044, respectively), compared to baseline. The present study thus demonstrated that time domain variables (i.e., SDNN, rMSSD, and pNN50) increase post WBV. ConclusionsOlder individuals are at high risk of developing cardiovascular diseases. As seen in the study, WBV improves HRV; and may help reduce risk of cardiac ailments. Moreover, WBV does not require extensive physical activity on the part of the participant. This makes WBV potentially beneficial to the elderly population. Further studies on WBV using different frequencies and training schedules may improve its applicability in clinics.

Comparative Study of Stator Configurations of a Permanent Magnet Linear Oscillating Actuator for Orbital Friction Vibration Actuator

A PM orbital friction vibration actuator (OFVA) which composes four linear oscillating actuators (LOA) is proposed in this paper. This paper presents the design, analysis, and experimental validation of stator configuration of a permanent magnet LOA to improve its thrust force characteristics. First, the magnetized topology and the coil configuration are interpreted. The optimization design goal of the LOA was established and the end effects of the actuator are illustrated. The influences of stator design parameters on the performance of LOA were investigated and the optimal parameters have been identified with reference to the thrust force density and thrust force ripple. Results showed that a quasi‐Halbach magnetized E‐cored LOA with obtrapezoid teeth has the best electromagnetic performances of all the LOAs examined here. Finally, the predicted thrust force characteristics were validated by measurements on a prototype actuator.

Comparative investigation of permanent magnet linear oscillatory actuators used in orbital friction vibration machine

The paper describes the alternative designs and performances of a single-phase moving-magnet linear oscillating actuator (LOA) which has been developed for orbital friction welding. The influences of the pole ratio on the performance of the LOAs are investigated and the optimal parameters have been identified with reference to the thrust force characteristics. It can be illustrated that a quasi-Halbach magnetized LOA, in which the magnets are assembled on a nonmagnetic mover yoke, represents the best electromagnetic performances. Finally, the predicted thrust force-current characteristic of quasi-Halbach magnetized LOA is validated by measurements on a prototype actuator.

Analysis of the Vibration Characteristic for an Orbital Friction Vibration Actuator

Orbital Friction Vibration Actuator (OFVA) is a core component of Orbital Friction Welding (OFW), which is a novel apertureless welding technology utilizing friction heat to implement solid-state. By taking advantage of the special electromagnetic structure, OFVA can produce a contactless, radial, synchronous and rotating force with adjustable amplitude and phase upon the still mover which then vibrate according to the predetermined orbital. This paper analyzes the operational principle and structure of OFVA and conducts a mathematical analysis for a core issue about how to make the motion component of the OFVA generate circular moving trajectories. Vibration characteristic of are analyzed and the expressions of amplitude amplification factors as the moving component is moving in a circle are derived. Simulations are carried out to validate the theoretical analysis, which proved that the design was correct and engineering practical.

System Modeling and Operational Characteristic Analysis for an Orbital Friction Vibration Actuator Used in Orbital Vibration Welding

Orbital Friction Vibration Actuator (OFVA) is a core component of Orbital Friction Welding (OFW), which is a novel apertureless welding technology utilizing friction heat to implement ...

DFT study of the physicochemical characteristics and spectral behavior of new 8-substituted 1,3,7-trimethylxanthines

Nine biologically active theophylline derivatives were investigated using quantum chemical methods (density functional theory level). All calculations were performed at B3LYP/6-31G** level of theory. The electrostatic potential charges, highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) gap, dipole moment, vibration frequencies, and electronic spectra were calculated. Log P was determined by Ghose-Crippen method. All of the compounds under study are polar and negatively charged, which is necessary for their interaction with the receptors/enzymes. Majority of the compounds are lipophilic and they can easily diffuse through the cell membrane. The observed differences between the calculated and the experimental vibration frequencies in the Fourier Transform Infrared Spectroscopy (FTIR) spectra are established to be mainly in NH and OH bands, due to hydrogen bonds formation. The discrepancies between theoretical and experimental electronic spectra may be due to vibration effects and H-bonding with the solvent molecules. The obtained results show that this type of spectrum is formed mainly by the xanthine fragment of the molecule, especially in the fingerprint region. All calculated properties could be useful for future qualitative-structure activity relationship (QSAR) analysis. © 2012 Wiley Periodicals, Inc.

FPSO 심정용 수직 해수펌프의 로터다이나믹 과도해석

This paper deals with the detail rotordynamic analysis for the vertical rotor system as development of vertical sea water lift pump for FPSO deep well. In a vertical rotor system, since linearized stiffness and damping coefficients of fluid film bearing are no longer be valid, hence the transient response analysis considering a fluid film force for every journal position in the bearing needs to be required. In this study, the transient response analysis of the proposed vertical pump rotor system was carried out in dry-run and wet-run conditions, respectively. The results show that orbital vibration responses of the rotor system remain stable at rated speed and thereby operating reliability of the vertical rotor system is confirmed. To overcome complexity of calculation pr ocedure and time consuming calculation of transient analysis, the calculating technique of steady-state response analysis is also proposed. The results of steady-state response obtained by applying the proposed technique to the rotor system are good agreement with the reference results, that is, transient responses.

Comparison of orbital and linear vibration welding of thermoplastics

AbstractThis work was conducted to determine if there were any benefits with orbital vibration welding compared to linear vibration welding. The experiments were conducted using standard full‐factorial designs with each process and each material. Four materials, polypropylene/polyethylene copolymer (PP/PE), polycarbonate (PC), acrylonitrile‐butadiene‐styrene (ABS) and Nylon (PA), were studied with each process. The equipment used was a modified Branson VW‐4 with an orbital head that had isolated magnets. The same machine was used to weld with both linear and orbital motions. This was achieved by modifying the controlling parameters of the drive. It was found that compared to linear vibration welding, orbital welding had a reduction of cycle time by 36% and 50% in Phase I and Phase III, respectively. It was also found that orbital welding dissipated 56% and 100% more power than linear vibration welding in Phase I and Phase III, respectively. In addition, it was seen that orbital welding was able to universally join unsupported walls with higher strengths and better consistency compared to linear welding. Other benefits included: a difference in the appearance of weld flash and small increase in weld strength. Some of the limitations of orbital welding that were identified included the effects of disengagement and residual stresses. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Benefits of Induction Welding of Reinforced Thermoplastics in High Performance Applications

The advantages of magnetic implant induction welding technology for various thermoplastics were widely discussed since the mid-1980s in a series of technical articles and reports. In 1998-2003, we reported to the Society of Automotive Engineers, our technical achievements in optimizing the mechanical performance of welded nylon (6, 66, 6/66, 46, etc.) using frictional (linear and orbital vibration, ultrasonic), contact (hot plate), and noncontact (laser through-transmission) welding technologies. Recent developments in magnetic implant induction welding have focused on optimizing the mechanical performance of joints in reinforced plastics through continuous improvement to the welding technology (including magnetic implant material properties, SPC process control, joint design optimization, etc.). In this study, 33 wt.% fiber-glass reinforced nylon 6 is used in a chain-optimization study to conduct a critical comparison of two alternatives for thermoplastic welding. Results demonstrate interactions between material composition, joint design, and welding process conditions.

Analytical solution of attitude motion for spacecraft with a slewing appendage

This paper investigates pitch motion and in orbital plane elastic vibration of a spacecraft with a flexible beam type appendage undergoing prescribed slew maneuver. The governing equations are transformed into a standard quasi-linear form, and then solved by Butenin's variation of parameters approach. Validity of the analytical solutions is assessed over a range of system parameters and initial conditions by comparing them with the results of numerical integration. The results show that they are very good approximations and provide extensive insight into the dynamical response of the system.

Potato digging using orbital vibration

A theory of orbital (circular) vibration in the vertical plane through the row has been developed in order to predict the performance of a vibratory potato digger. The theory was based on an analysis of the motion of the digging blade in the soil and the blade-soil forces. The theory predicted a decreasing draught force and an increased power requirement as the velocity ratio (the ratio of the vibrating blade tip velocity to the velocity of the vibratory blade carrier) increased. The validity of the theory was field-tested using a prototype vibratory digger operated at a speed of 3 km/h, a nominal digging depth of 200 mm, vibration amplitudes of 10–25 mm and frequencies of 7·5–18 Hz. Reasonable agreement between experimental and theoretical draught ratios was achieved. The experimental power ratios, however, were substantially higher than those predicted by the theory. In addition to decreasing the draught requirement, the prototype digger decreased potato damage and losses when compared with conventional non-vibratory potato diggers.

CABLE BURIAL IN THE DEEP OCEAN FLOOR

ABSTRACTBottom fishing equipment employed by scallopers and trawlers routinely damage or break important Navy Oceanographic cables resulting in substantial repair coats and unacceptable system interruption. The Civil Engineering Laboratory (CEL), sponsored by the Naval Facilities Engineering Command (NAVFACENGCOM), has been developing and validating an engineering concept for a Deep Ocean Cable Burial (DOCB) System. This DOCB System will providethe Navy with an efficient, effective and reliable means of burying cables 3‐feet deap in ocean mediments, at speeds not less than one knot, to water depths of 6,000 feet.The DOCB System b a remotely controlled machine which underruns and buries existing (previously laid) cables. It is powered and controlled from a surface ship via an electromechanical umbilica cable. The machine is self‐propelled by ducted thrusters and supported on water lubricated skids. The excavation system computer an orbital vibrating plowshareand a vertical waterjet. Full‐scale field testing at CEL baa keyed on three areas: Quantifying the reduction in drawbar force achieved by applying orbital vibration to an upward cutting plowshare. Evaluating a Vertically impinging jet nozzle for depth of a cut M a function of jet operating parameters. Demonstrating the effect on the soil drag of a flat‐bottomed skid due to forcing a thin layer of water between the skid and the seafloor. The field teats of an orbital vibratory plow were performed in a 1 to 2 psi clay simllar to that found on the ocean floor. The results showed that a 70% reduction in drawbar force was achieved by applying an elliptical orbital vibration. It was also shown that the vibration feature would split or push aside buried rocks which would have stalled a conventional stationary plow.The water jet tests demonstrated that a 2 1/2‐in. nozzle cuts 36‐in. deep in 1 to 2 psi clay. The nozzle pressure was 75 psi and flow was 1,200 gpm. The water jet did not produce a clearly defined trench, but it broke up the soil sufficiently for passage of a cable feedshoe. Finally, it was shown that forcing a layer of water between the skid and soil reduced the skid/soil drag by 50% in both sand and clay soils.The results of the field tests, coupled with a thorough feasibility/preliminary design study performed by others under contract to CEL, has brought the DOCB concept to the point where design and fabrication of a full‐scale operational prototype call be initiated.

The Orbital Movement and the Damping of the Fluidelastic Vibration of Tube Banks Due to Vortex Formation: Part 2—Criterion for the Fluidelastic Orbital Vibration of Tube Arrays

The phenomenon on the tubes in a tube row, which vibrate alternately along the row in the transverse and stream-wise directions, will be explained by a vortex model. This model consists of the symmetrical vortex pair trains behind the stream-wisely vibrating tubes, and the Karman vortex streets behind the transversely vibrating tubes. It will be shown in the paper that the coupling between these two groups of vortex systems can excite the tube arrays to perform this fluidelastic vibration. A criterion for the onset of this orbital movement will be given with the expression ξ = R/Sxt. This criterion predicts a strong fluidelastic vibration for tubes with low transverse tube spacings and low natural flexible frequencies in a high speed flow. The theory leading to this criterion is based on the phenomenon of the variation in the position of the separation point for the free shear layer during the cylinder vibration. A switching of the jet for maintaining the fluidelastic vibration is then a result of this variation.