Tooth Vibration Research Articles

Dynamic response of circular saw blade based on dynamic sawing force model in machining hard aluminum alloys

Carbide circular saw blades are indispensable tools extensively utilized in aerospace and transportation industries. However, modeling of sawing force and dynamic behavior of circular saw blades with large diameter-thickness ratio has rarely been reported. Hence, the aim of this study is to predict the scratches caused by saw tooth vibration on the sawing surface by proposing an axial vibration model for circular saw blades based on the dynamic sawing force. First, the dynamic undeformed chip thickness is established based on the sawtooth element movement method, which presents the circular saw blade geometry, sawing parameters, and so on. A novel dynamic sawing force model is built using this undeformed chip thickness. Then, the axial dynamic response is solved by the additional axial force introduced by the dynamic sawing force. Finally, sawing experiments were carried out, and the results confirmed the feasibility of the model.

Influence of the elasticity variation of the 3D printed PMMA structure on the axial tooth vibration

Recently, 3D printing with poly methyl methacrylate (PMMA) has been widely used in dentistry: 3D printing is a suitable method for producing any complex three-dimensional shape, and PMMA is a material that has suitable properties in the oral cavity environment. That is why 3D printing is very often used to make PMMA teeth. There is the impact between teeth during chewing that causes shape variation and tooth vibration. As cyclic vibrations adversely affect the durability of PMMA teeth, they must be eliminated. The object of this work is to study the axial vibrations of a 3D printed tooth, as well as to give recommendations for modifying the PMMA structure with the aim of vibration damping. Tooth vibration is mathematically modeled and analytically solved. The obtained result provides a link between the vibrational properties and the elasticity variation of the PMMA material. The function that defines the change in elasticity of PMMA depends on the ?slow time?. (The term ?slow time? implies a product of time and a parameter that is less than one). For a decreasing elasticity function, the vibration is of damped type: for higher is the elasticity reduction, the faster is the vibration decay. Based on the determined elasticity function, the modification of the PMMA structure can be realized. Authors propose the application of the obtained elasticity variation function for programming 4D printing with modified PMMA.

Research on Multiobjective Optimization Design of Meshing Performance and Dynamic Characteristics of Herringbone Gear Pair Under 3D Modification

Abstract Herringbone gear transmission system is widely used in high-speed overloaded fields such as ships. Tooth deformation and installation error, which can cause meshing impact, load mutation, and load uneven, will seriously affect dynamic performance of the whole transmission system. Modification technology is the most effective way to achieve damping and noise reduction. In this article, we propose a three-dimensional (3D) modified tooth surface by grinding wheel along axial to the spiral rise and along radial to the parabolic movement based on the grinding principle and a multiobjective ant lion optimizer model for optimizing meshing performance and dynamic characteristics of herringbone gear transmission system and analyze the impact of optimized modifications of tooth profile, axial, and three dimension on meshing performance, loaded transmission error, load distribution coefficient and meshing impact, meshing stiffness, and vibration acceleration by the example. The results show that the 3D modification of optimization can not only eliminate the contact between the tooth side edge and tooth top edge but also eliminate the influence of installation error on contact performance. The root mean square values of the relative comprehensive vibration acceleration of tooth profile modification, axial modification, and 3D modification are reduced by 30.11%, 49.24%, and 61.41% compared with the standard, respectively. The 3D modification can greatly reduce tooth vibration, reduce resonance peak, and achieve the goal of noise reduction.

Effect of mass variation on vibration properties of the tooth in drilling operation

Dental cavity represent one of the widespread illness of the tooth. Method for treating of the tooth is to drill the cavity and to fill the hole with suitable material. Measurements show that during drilling the tooth vibrates with increasing mass that causes unpleasant feeling for patient. The aim of the paper is to give the theoretical explanation for this phenomena and to give suggestion for vibration elimination. During drilling, mass of the tooth is decreasing and the so called ‘reactive force’ occurs. Drilling and reactive force cause tooth vibration. The system is modeled as a nonlinear time variable system. An analytical procedure for solving of the equation of vibration is developed. The solution is assumed in the form of the generalized trigonometric function with time variable amplitude and phase. It is obtained that not only the amplitude but also the frequency of tooth vibration in drilling are increased. In addition to reactive force the drilling velocity, diameter of the drill tool and spindle speed affect the vibration level. The appropriate values of these parameters would eliminate or decrease the patient bad feeling.

Measuring tooth vibrations induced during cavity preparation with time-averaged holography and its influence on near vision acuity in dentists.

The aim of this study was to quantify vibrations and their influence on visual acuity. The study consisted of two parts, laboratory and clinical. Time-averaged holographic interferometry (TAHI) method was used in laboratory for measuring the amplitude of tooth vibrations induced by dental handpiece. The amplitudes of tooth vibrations were measured for the three diameters and three speeds. The larger diameter coupled with increasing speed resulted in greater vibration amplitudes, whereby a maximum amplitude of less than one micrometer was detected. For quantifying the natural visual acuity for the corresponding tooth vibrations, we have used the clinical condition approach with miniaturized Snellen optotype as an assessing tool. Central visual acuity did not display variance in visual acuity at rest or under load. Results indicate that the vibrations induced during cavity preparation are not sufficient to negatively affect visual acuity of dentists.

Application of modified generalized trigonometric functions in identification of human tooth vibration properties

Summary In this paper the generalized trigonometric functions are modified for solving of the ordinary differential equation describing the motion of the strong nonlinear oscillator. The generalized trigonometric functions related to the p-Laplacian, which is the nonlinear differential operator, are modified for solving equations with nonlinearity of any rational order. Based on the modified generalized trigonometric function (MGTF) and the known Krilov-Bogoliubov method (KBM) the new, so called, MGTF – KBM method is developed. The method is applied for solving perturbed second order equations of oscillatory motion. As an example the oscillatory tooth motion excited with initial impulse force is considered. The tooth-support system is modeled as a strong nonlinear oscillator. The analytically obtained vibration properties of the tooth are compared with experimentally obtained one and show a good agreement.

Research into Correlation between the Lubrication Mode of Contact Surfaces and Dynamic Parameters of Turbo-Generator Transmissions

The paper presents the results of an experimental study aimed at assessing the correlation between the measurement of dynamic parameters (vibration, high-frequency vibration, and acoustic emission) and the analysis of friction mode and the state of lubrication of the contact surfaces of two gearboxes in the turbo-generator assembly (high-speed single-body steam turbine—gearbox—generator) with the transmission power of no more than 50 MW. The analysis confirmed the assumption of a significant correlation of the monitored high-frequency vibration signal with the unsatisfactory engagement of the gear teeth. Through vibration analysis, an increased level of the tooth vibration component and vibration multiples with increased acoustic emission were identified in gearbox operation. The gear oil of one of the gearboxes examined showed a loss of additive elements in the real operation of the contact surfaces of the teeth engagement. The trend analysis confirmed the complexity of the monitored transmission operation in terms of the friction mode and the influence of the oil quality on the state of the tooth flank microgeometry.

Multi-objective optimization of tooth surface based on minimum of flash temperature and vibration acceleration root mean square

Marine ship gears are increasingly subject to strict requirements in terms of tooth surface load capacity, dynamic performance, vibration and noise generation, and so on. The optimization of tooth ...

Dynamics of High-Speed Precision Geared Rotor Systems

Gears are one of the most widely applied precision machine elements in power transmission systems employed in automotive, aerospace, marine, rail and industrial applications because of their reliability, precision, efficiency and versatility. Fundamentally, gears provide a very practical mechanism to transmit motion and mechanical power between two rotating shafts. However, their performance and accuracy are often hampered by tooth failure, vibrations and whine noise. This is most acute in high-speed, high power density geared rotor systems, which is the primary scope of this paper. The present study focuses on the development of a gear pair mathematical model for use to analyze the dynamics of power transmission systems. The theory includes the gear mesh representation derived from results of the quasi-static tooth contact analysis. This proposed gear mesh theory comprising of transmission error, mesh point, mesh stiffness and line-of-action nonlinear, time-varying parameters can be easily incorporated into a variety of transmission system models ranging from the lumped parameter type to detailed finite element representation. The gear dynamic analysis performed led to the discovery of the out-of-phase gear pair torsion modes that are responsible for much of the mechanical problems seen in gearing applications. The paper concludes with a discussion on effectual design approaches to minimize the influence of gear dynamics and to mitigate gear failure in practical power transmission systems.

Reducing the vibration of a chevron gear transmission

A mathematical model is proposed for tooth vibrations in chevron gear transmissions. Methods of reducing the vibrations in spiral engagement are outlined.

Simultaneous measurements of aeroacoustic sounds and wall vibration for exploring the contribution of tooth vibration in the production of sibilant sounds/s/

In order to understand the contribution of teeth vibration to the production of sibilant/s/, the pre-sent study was designed to develop a method of simultaneously measuring aeroacoustic sounds and the vibration of an obstacle. To measure the vibration without disturbing flow, the Michelson interferometer was employed. The flow channel, which had an obstacle wall inside of it, was fabricated such that it morphologically mimicked the simplified geometry of the oral cavity. Given airflows at a flow rate of 7.5 × 10–4 m3/s from the inlet, aeroacoustic sounds were generated. A spectrum analy-sis of the data demonstrated two prominent peaks in the sound at 1,300 and 3,500 Hz and one peak in the wall vibration at 3,500 Hz. The correlation in peak frequencies between the sound and wall vibration suggests that the sound at 3,500 Hz was induced by the wall vibration. In fact, the sound amplitude at 3,500 Hz decreased when the obstacle wall was thickened, which increased its rigidity (p < 0.05, t-test). The experimental results demonstrate that the developed techniques are capable of measuring aeroacoustic sound and obstacle wall vibration simultaneously, and suggest the potential to pave the way for detailed analysis of the production of sibilant sounds /s/.

小児・発達障がい児歯科支援におけるレーザーのエビデンスとその効果

Laser treatment of tissue is likely to be more effective than conventional treatment if a suitable wavelength for the treatment is chosen. However, it is not easy to confirm the effects because a laser's effects are fine and not easy to evaluate, so some innovation is necessary.Additionally, if we compare laser treatment with the conventional method, we can confirm the features and problems of the conventional method, which may result in ideas for overcoming the problems.This laser study enabled us to not only identify the effects of the laser, but also to clarify the problems of conventional methods, thus yielding valuable data as evidence. Synergistic effects may also have a big impact for dental evolution.When deciding on treatment options, it is more important for patients to be able to see, compare and understand data rather than to receive merely an oral explanation. This will strengthen the relationship between doctor and patient.After over 10 years of basic study on how the clinical application of Er:YAG laser affects hard tissues, we have obtained interesting results on tooth vibration and the characteristics of the surface after Er:YAG laser ablation.This paper outlines the data and possibilities Er:YAG laser for dental support of children and patients with developmental disorders, and shows how the laser can create a better future for pediatric dental support.

Modal analysis of maxillary central incisor tooth

The purpose of this study was to investigate the vibration modes of tooth and explain the vibration characteristics of tooth. By using the finite element method (FEM) software, the Eigen vibration of 3-D finite element model of maxillary central incisor tooth was analyzed. Crown vibration was dominantly present in the natural modes. In general, tooth vibration was mostly dominated by the first 4 natural modes and the natural frequencies of the tooth studied were 879.65, 1286.76, 1827.21 and 2087.59 Hz, respectively. Corresponding natural mode shapes were as follows: 1st, the whole tooth vibrates along its axis in crown to root direction; 2nd, the crown swings mainly in labio-lingual direction; 3rd, the crown twists about its axis; and 4th the crown swings mainly in mesio-distal direction. The present data suggest that the modal analysis can be successfully applied in the field of study on the tooth under the loading of masticatory force. Key words: Tooth, vibration, modal analysis, frequency.

56th Annual Meeting of the American Academy of Implant Dentistry and the World Congress of Oral Implantology 7 Abstracts, 2007

56th Annual Meeting of the American Academy of Implant Dentistry and the World Congress of Oral Implantology 7 Abstracts, 2007

Measuring tooth mobility with a no‐contact vibration device

Mechanical parameters obtained from the frequency response at tooth vibration informs of various periodontal tissue conditions. An electromagnetic vibration device was investigated for measuring tooth mobility using mechanical parameters obtained from the frequency response characteristics of an experimental tooth model. This electromagnetic vibration device was able to assess the overall condition of periodontal tissue associated with the alteration of each parameter. In this study, reliability and effects of bottom thicknesses of simulated periodontal ligament relative to mechanical parameters were analysed. Measurement of tooth vibration was performed by an electromagnetic vibration device on experimental tooth models with different bottom thicknesses of simulated periodontal ligament. Using an electromagnetic vibration device, the mechanical parameters resonant frequency, elastic modulus and coefficient of viscosity were calculated from the frequency response characteristics derived from tooth vibration by an electromagnetic force. Variation of those parameters was investigated under four different experimental conditions and the implications of the results were discussed. An electromagnetic vibration device clearly detected three mechanical parameters in all experimental conditions. The resonant frequency and the elastic modulus decreased with increasing bottom thickness. However, no significant difference in the coefficient of viscosity was observed among the experimental conditions. Assessment of tooth mobility using mechanical parameters of an electromagnetic vibration device reproduced fine details of various simulated periodontal ligament conditions. Variation in the parameters resonant frequency, elastic modulus and coefficient of viscosity might be useful in evaluating changes of components in periodontal tissues.

Determination of tooth cogging force in a hard-disk brushless DC motor

The paper proposes a new method to determine the tooth cogging force in a brushless DC (BLDC) motor which is used in a hard-disk application. This force might be a source of tooth vibrations and motor noise. In the new method, the permanent-magnet (PM) poles are substituted with their equivalent currents. Then, the conformal mapping (CM) method is applied to determine the PM magnetic field. Finally, the cogging force is determined by integrating the magnetic field pressure over the tooth surface. The paper also analyzes the harmonic content of both radial and tangential force components.

Terfenol-D tooth phone performance characterization and optimization

A Terfenol-D transducer has been developed for use as a tooth phone with both sensing and actuating capabilities by Audiodontics, Inc. This research focuses on characterizing the sensitivity of the tooth phone’s magnetostrictive Terfenol-D rod performance in both sensor and actuator modes to changes in the initial prestress of the device. A test apparatus was designed to allow prestress variability while operating the transducer as either a sensor or an actuator. To assess the sensor-mode performance, a force-feedback loop control system was used to excite the tooth phone with a constant force from a mechanical shaker at the tooth–tooth phone interface surface while measuring the voltage generated in the transducer’s coil. The shaker was driven with a 200Hzto7kHz swept sine at various dynamics force loadings for prestresses ranging from 0.25to3.5ksi. The results indicate a prestress of 2ksi offers the best sensor-mode performance. To assess the actuator performance, a accelerometer was attached to the tooth–tooth phone interface surface and output acceleration was recorded while sweeping the tooth phone excitation frequency from 200Hzto7kHz with zero-to-peak voltages of 0.1, 0.3, and 0.5V. The prestress settings were varied from 0.3to3.25ksi. As an actuator, no prestress offered a significant broadband performance advantage. Finally, comparisons were made of the tooth phone and an accelerometer for measuring tooth vibrations induced during humming. They perform similarly and capture much of the frequency content found in concurrently recorded microphone data.

Effects of irradiated conditions of Er:yttritium–aluminum–garnet laser on tooth vibration

Clinical studies that the Er:yttritium–aluminum–garnet (YAG) laser cause less pain in cutting. Unlike high-speed drilling Er:YAG laser irradiation does not cause pain by vibration, pressure, heat, or noise. We suspected that the greatest difference in characteristics between the Er:YAG laser and the high-speed drill is the amount of tooth vibration during cavity preparation. It will be simultaneously pain or discomfort during tooth cutting. Previously, the authors revealed that increased vibration speed was observed with an increase in Er:YAG laser irradiated energy, and different characteristic of Er:YAG laser and high-speed drill. However, the vibration speed was also influenced by other irradiated conditions. The purpose of this study was to determine the effects of various irradiated conditions of Er:YAG laser preparation on the vibration speed of the tooth. Four extracted permanent upper first premolars setup the plaster basement. The experimental periodontal tissue was selected of silicone impression material. The vibration speed and frequency characteristics were analyzed by using a laser Doppler vibrometer. The laser irradiation energy was applied 145 mJ; and the repetition rate examined was 1, 3, 5, and 10 Hz. The water flow rate was set at 5, 10, and 15 ml/min; and distance between irradiation tip and the tooth surface examined was 0 (contact), 0.5, 1, 1.5, and 2 mm. The highest vibration speed was significantly obtained with the following values: 10 Hz, 10 ml, and contact irradiation. These results suggest that other irradiation conditions, in addition to the energy level affect tooth vibration speed and may be linked to preparation efficiency.

Basic study on vibrations of tooth preparations caused by air turbine, quintuple speed handpiece, and Er:YAG Laser

The aim of this study was to evaluate tooth vibration obtained with the Er:YAG laser and high-speed drills. The rotational apparatuses used were the air turbine and the quintuple speed handpiece. Five of the extracted upper first premolars were built up on the plaster box. Silicone impression material was selected as experimental periodontal tissue in this study. The vibration speed and frequency characteristics were measured by using a laser Doppler vibrometer, which has a high accuracy and reproducibility compared with acceleration pickup. We found that small vibration of the tooth occurred with the Er:YAG laser preparations. The rotational drill preparation caused greater tooth vibration with a frequency peak in or near the domain which had the high sensitivity of hearing compared to the Er:YAG laser, suggesting them to be the primary factors of provoking pain and discomfort during tooth preparation.

Changes in periodontal pulsation in relation to increasing loads on rat molars and to blood pressure

Pulsation originating from the vascular system of the periodontal ligament (PDL) is apparently synchronized with the heartbeat. As periodontal pulsation causes pulsatile tooth vibration, it might be possible to evaluate it indirectly by measuring tooth vibration. Periodontal pulsation has been found to be dependent on blood flow and blood pressure in the PDL. Heavy orthodontic force is known to reduce blood flow and decrease the amplitude of the pulsation. The purpose now was to examine (1) the magnitude of the experimental orthodontic force that will impair PDL blood flow; and (2) the differences in the amplitude of pulsation between normal and hypertensive animals. The experiments were performed on 10 Wistar, 10 Dahl S and 10 Dahl R rats. Hypertension was induced in Dahl S rats. The head and maxilla of anaesthetized animals were immobilized. Mesial tipping forces of different loads (0.098–0.882 N) were applied to a molar and periodontal pulsation was measured with a highly sensitive laser displacement meter. The periodontal pulsation at each load resembled a blood-volume pulse wave. Its amplitude began to decrease at a load of 0.588 N in Wistar and Dahl R rats, and at 0.784 N in Dahl S rats. The group with induced hypertension had a significantly larger amplitude than the other two groups when 0.588 N was applied. These results suggest that: (1) periodontal pulsation can indicate a PDL overload; and (2) that systemic blood pressure affects the amplitude of periodontal pulsation during loading.