Vibrations

The present work aims to study the water-stop tray, a front-loading component of a washing machine. As most of the components of washing machines, the water-stop tray suffers significant vibrations especially when the spin speed increases. A vibrational analysis of the current typical design was realized. Then, four modified trays were investigated and a hammer impulse response was recorded using 13 accelerometers in order to measure the frequency response of each tray. The results allow to identify the key parameters that affect the vibrational response of a water-stop tray. Finally, the comparative analysis among the different designs allows to select the tray with the lowest vibration amplitude.

In this study, the mechanical buckling and free vibration analysis of the nanobeams made of functionally graded materials in the framework of nonlocal strain gradient theory in conjunction with a refined higher order shear deformation beam model. The material composition of the FG nanobeam is assumed to vary continuously in the longitudinal direction based on a power-law model distribution. The small scale effect is taken into consideration based on nonlocal elasticity theory of Eringen. Hamilton's principle is applied to obtain the governing differential equation of motion and boundary conditions and they are solved applying analytical solution of buckling load, and natural frequency are presented for a simply supported beam, and the obtained results compare well with those predicted by the nonlocal Timoshenko and Reddy beam theories.

The Global Search Method (GSM) is being proposed for global evaluation of complex structures. This method is based on the analysis of the flexural wave propagation and the comparison of the real structure responses to those from a calibrated simulation model representing the non-damaged condition. Then, the differences are associated to changes in the structural parameters (stiffness, damping, mass, and geometry) or the boundary conditions, and related to a specific region or location within the structure to locate damage and quantify its overall structural effect. The effectiveness of the GSM was evaluated on a cable stayed bridge where damage was simulated when a cable was removed during rehabilitation; dynamic tests were done using a Falling Weight Deflectometer to control the dynamic impact load and previously analogous tests were done to calibrate the finite element model. Results show that the GSM has the ability to identify and quantify damage, where sensitivity increases when the sensors are closer to damage. In the bridge case, damage could not be detected when the distance of the sensors was greater than 65 meters from damage because of signal attenuation.

Due to very force competition, all producer, not only manufacturers of gearboxes, have been forced to constantly improve their products. This has led to the harmonization of the technical characteristics of their gear units, even though they are not yet defined by the standard. Modern solutions of universal helical gearboxes are characterized, first of all, by large torque capacity and high values of gear ratio in the frame of relatively small overall dimensions of the gear unit. This paper provides an overview of common activities undertaken by manufacturers of universal helical gearbox to improve technical characteristics of their products.

Державне підприємство "Конструкторське бюро "Південне" Інститут проблем машинобудування ім. А.М.Підгорного НАН України Харьківський національний університет імені В.Н.Каразіна АНАЛІЗ СХЕМ ПРИКЛАДАННЯ НАВАНТАЖЕНЬ ПРИ МОДЕЛЮВАННІ МІЦНОСТІ ЗВАРНИХ ШВІВ З УРАХУВАННЯМ ВЗАЄМНОГО ВПЛИВУ РІЗНИХ ДЕФЕКТІВ Метою даного дослідження є вивчення концентрації напружень в зварних швах конструкцій, підданих одночасної дії інтенсивних силових і температурних факторів. Розглядаються пластинчасті конструкції. Вважається, що в зварних швах, які з'єднують пластини, можуть знаходитись тріщини, пори та інші дефекти. Зміна тиску і температури по поверхнях пластин може істотно вплинути на розкриття тріщин у звареному шві. В роботі досліджені три розрахункових схеми, що характеризують силовий і температурний впливи на пластинчасту конструкцію. Аналіз величин коефіцієнтів інтенсивності напружень за трьома запропонованими розрахунковим схемам довів, що результати відрізняються в межах від 0,5% до 2%, проте час розрахунку за першою схемою істотно менший, і визначені коефіцієнти інтенсивності напружень відрізняються не більше ніж на 1% від даних, отриманих аналітичним методом. Саме така схема може бути використана для швидкої оцінки стану конструкції. Ключові слова: силове навантаження, температурне навантаження. включення, пора, зварний шов, метод скінченних елементів

Dynamic characterization of cantilevered cracked plates assumes importance for a variety of applications including aging aerospace, mechanical and ship structural components. In this paper modal characteristics of isotropic plates with damage identified as cracks are investigated. The paper describes results obtained by finite element simulation of cracked plates. The frequency degradation as a function of the crack length is presented for selected aspect ratios. Some damage metrics are developed based on the modal parameters to describe the structural integrity of the plate type structures with root cracks. Frequency response analysis is presented to show the effect of the crack growth on the response of the plates. Some suggestions are developed based on the observations of the simulation for health monitoring of structural components.

Jets are ubiquitous in astronomy. It has been conjectured that the existence of jets is intimately connected with the spin of the central object and the viscous angular momentum transport of the inner disk. Bipolar jet-like structures propelled by the viscous torque on a spinning central object are also known in a completely different context, namely the flow in the laboratory of a viscoelastic fluid. On the basis of an analogy of the tangled magnetic field lines of magnetohydrodynamic (MHD) turbulence to the tangled polymers of viscoelastic polymer solutions, we propose a viscoelastic description of the dynamics of highly turbulent conductive fluid. We argue that the same mechanism that forms jets in viscoelastic fluids in the laboratory may be responsible for collimating and powering astrophysical jets by the angular momentum of the central object.

Resumen La existencia de varios programas en el mercado, específicamente en el área del cálculo estructural, las cuales se utilizan en diversas investigaciones, que permiten al ingeniero estructurista obtener resultados adecuados. En este trabajo de investigación se realizó el modelamiento del Hospital Challhuahuacho de su bloque "A", utilizando el software CYPECAD para su interpretación de datos. Para ello se realizó el pre dimensionamiento de los diferentes elementos estructurales tales como: losas macizas, vigas, columnas y placas, para el análisis sísmico se consideró los parámetros de la norma peruana E.030 diseño sismorresistente de acuerdo a la zona de estudio. Después del modelamiento se procedió a interpretar los datos obtenidos como momento y cortantes de los diferentes elementos estructurales, siendo la columna de análisis C-8 la más crítica, el resultado de sus momentos son considerables; por ello se propone aplicar placas de concreto armado en sitios estratégicos para contrarrestar las fuerzas laterales, Así mismo se realizó la comparación de los datos obtenidos del expediente técnico de las variables como: los espectros, peso de la estructura, cortante basal estático y dinámico, los datos de estas variables varían por factores que son justificados en este trabajo de investigación.. Palabras clave: Software; cypecad, modelamiento, análisis, estructurales.

The analysis presented here is to study the effect of thermal gradient on the vibration of visco-elastic square plate (having clamped boundary condition on all the four edges) of variable thickness whose thickness varies linearly in both directions. Two dimensional thermal effects on frequency of free vibrations of a visco-elastic square plate is considered. It is also considered that the temperature varies parabolically in two directions and thickness of square plate varies linearly in two directions. An approximate but quite convenient frequency equation is derived for a square plate (clamped at all the edges) by using Rayleigh-Ritz technique with a two-term deflection function. Both the modes of the frequency are calculated by the latest computational technique, MATLAB, for the various

Railway pads are a type of component that is used in railway construction and maintenance. They are typically made of rubber or similar material and are placed between the railway sleeper and the rail itself. Railway pads provide a layer of cushioning and insulation between the rail and the sleeper, which helps to reduce noise and vibration from passing trains. Railway pads can also help extend the rail's life by reducing the wear and tear caused by constant friction between the rail and sleeper. They are especially useful in areas where noise pollution is a concern, such as residential areas or near hospitals and schools. Several types of railway pads are available, including continuous, discrete, and ribbed designs. The specific type of pad used will depend on factors such as the type of rail being used, the expected loads and speeds of passing trains, and the requirements of the railway system. Overall, railway pads are an important component in the construction and maintenance of railway systems, helping to reduce noise and vibration while also prolonging the life of the rail and other components. In this paper, we are testing three types of vibration rubber pads i.e., Ethylene  Propylene Diene Monomer (EPDM), High-Density Polyethylene (HDPE), nitrile and comparing three vibration frequencies. The dynamic frequency of welded rails with HDPE pads has having 1190 Hz mean value. The dynamic frequency of rail tracks with single- and double-layer EPDM pads their mean values are 499 Hz and 335 Hz respectively. The experimental values clearly show that single- and double-layer EPDM pad dynamic frequencies are reduced by up to 58% and 71%, respectively, over the HDPE pad.

L'augmentation du prix de l'énergie, les contraintes environnementales ainsi que les exigences du marché mondial imposent aux fabricants d'équipements hydrauliques de produire des composants toujours plus compétitifs et de plus en plus performants. Face à ces exigences l'innovation est primordiale. La recherche et le développement ayant pour vocation la mise en oeuvre de solutions nouvelles ainsi que la compréhension des phénomènes physiques constituent la véritable pierre angulaire de la discipline. Le développement conventionnel d'une pompe fait appel à la méthode expérimentale essais-erreurs avec itérations successives longues et couteuses. L'intégration de la simulation numérique permet une optimisation des produits par prototypage virtuel tout en réduisant considérablement le coût et le temps de développement. L'objectif de notre travail est d'établir une stratégie de conception et d'optimisation des pompes hydrauliques en utilisant les outils de simulations. Dans cette stratégie, l'insertion des plans d'expériences numériques permet de modéliser les performances d'un système sous la forme de surfaces des réponses. Cette modélisation donne accès aux configurations de paramètres de conception qui minimisent ou maximisent un critère de performance.

A pseudo-static coefficient is required for pseudo-static analysis of mechanically stabilized earth (MSE) walls, but there are no clear criteria for its selection. The current study assessed the horizontal pseudo-static coefficient (kh) for MSE walls by considering the effects of a tiered configuration and reinforcement type. For this purpose, by selecting two reinforcement types (steel strip and geogrid), six two-tiered MSE walls with three different offset distances and two integrated MSE walls (without tier) were prepared and then were shaken using shaking table tests to determine the geometry of the slip surfaces and the force distribution along the reinforcements at the failure stage. The physical models then were simulated using the limit-equilibrium horizontal slice method to estimate the value of kh required to establish slip surfaces and reinforcement forces similar to those observed in shaking table tests. Because the equivalent pseudo-static coefficients obtained were the corresponding to failure stage, they were considered as the upper bound values. The analytical models used a new formulation of the horizontal slice method (HSM) based on the slip surfaces observed in the shaking table tests. This formulation made it possible to determine the distribution of kh along the wall height as a function of the reinforcement type, offset distance, and PGA. It was found that, as the offset distance increased, the pseudo-static coefficient required for the upper and lower halves of the tiered wall models increased and decreased, respectively. This was observed in both types of reinforcement, but was more prominent in walls reinforced with metal strips. Moreover, the distribution of kh along the wall height showed that a lower pseudo-static coefficient was required for the upper layers of the integrated walls, but the reverse was true when using a tiered configuration. This change in the trend of the kh distribution, which was due to the increase in the dimensions of wedge failure in the lower half and a decrease in dimensions in the upper half of the wall required a larger coefficient in the upper layers of the tiered walls.

Pseudo-static coefficient  Two-tiered mechanically stabilized earth wall  Shaking table test  Horizontal slice method

Laryngeal models have contributed much to our understanding of vocal-fold function in recent years. A major achievement of modeling work has been to quantify the conditions required to initiate and maintain vocal-fold oscillation in larynx-like systems [1-6]. This work has indicated that achieving phonation requires a balance between vocal-fold parameters and aerodynamic forces. Vocal-fold parameters include the position of the vocal folds (degree of adduction, glottal shape), thickness of the folds, and tissue characteristics (longitudinal tension, damping), whereas aerodynamic factors include the transglottal pressure and the Bernoulli effect. Developing realistic models and assessing their ability to account for voicing behavior across speakers requires having data on the conditions around phonation thresholds in multiple speakers. The goal of the work reported

Strategies for condition monitoring are relevant to improve the operation safety and to ensure the efficiency of all the equipment used in industrial applications. The feature selection and feature extraction are suitable processing stages considered in many condition monitoring schemes to obtain high performance. Aiming to address this issue, this work proposes a new diagnosis methodology based on a multi-stage feature reduction approach for identifying different levels of uniform wear in a gearbox. The proposed multi-stage feature reduction approach involves a feature selection and a feature extraction ensuring the proper application of a high-performance signal processing over a set of acquired measurements of vibration. The methodology is performed successively; first, the acquired vibration signals are characterized by calculating a set of statistical time-based features. Second, a feature selection is done by performing an analysis of the Fisher score. Third, a feature extract...

Vibisol International AB, Ferievagen 25, Bromma, Sweden ABSTRACTS: Ground vibrations are of increasing importance, especially in industrialized countries. Aspects of importance for wave propagation in soil deposits are presented. The effect of wave bending due to increasing wave velocity with depth is discussed. The vibration effectiveness of open trenches is reviewed, based on theoretical studies and model tests. The concept of the gas cushion screen for permanent ground vibration isolation is described. The boundary element method was used to compare the vibration isolation effect of an open trench with that of a gas cushion screen. The analytical results are compared with field tests. Design recommendations for ground vibration isolation measures are given. 1. INTRODUCTION The importance of ground vibrations from man-made activities has increased during the past decades, especially in densely populated areas and industrial zones. This is due to various factors, such as more inten...

Impact driving of piles is a complex process which depends on the interaction of the stress wave progressing down the pile and on the dynamic soil resistance along the shaft and at the toe. Pile driving vibrations can adversely affect adjacent structures, and the intensity of ground vibrations depends on the dynamic resistance along the pile rather than on the energy applied to the pile. The viscous damping factor, J c , is one of the fundamental parameters when the static pile resistance is determined from dynamic tests. Theoretical analyses and field observations show that the J c -factor is not solely a soil parameter, but a function of the ratio of pile impedance and soil impedance at the pile toe. Consequently, the pile toe damping factor for an open-toe pipe pile would be different when no plug develops in the pile and when the pile toe is fully plugged. Moreover, the mentioned aspect needs to be considered when the results of a test pile of one pile type are applied to a construction pile of a different type. Viscous damping along the pile shaft and at the pile toe is the source of ground vibrations. The vibration magnitude is governed by the interactive nature of dynamic pile-soil resistance, which is a function of the ratio between the pile impedance and the soil impedance for P-waves. It is shown that the vibration transmission efficacy and the dynamic resistance are inversely linearly proportional to the pile impedance, and that energy transmission efficacy correctly reflects the vibration emission from the pile to the surrounding soil layers. The literature includes several studies of comparisons between pile capacity determined in a static loading test to that determined in a CAPWAP analysis on dynamic records. Much of the agreement and non-agreement in such papers is due to that many of the comparisons include mistakes and a few sources of such are illustrated and explained. A case of over reliance on blow-count is presented.

We consider a chain of coupled micromechanical resonators as a delay line for radio-frequency signals. Wave propagation in the chain is generated and detected using capacitive transducers. Analytical results, numerical simulations and rst measurements for the response of a prototype device are presented. The delay line is shown to have a bandpass response and a very low signal group velocity of the order of only few meters per second. Weaknesses of the rst prototypes are identi ed through simulations and a more optimal design is suggested.

Th e article presents a case study on the Investigation of lateral vibrations in the turbine-generator unit 5 of the Inga 2 hydroelectric power plant in the Democratic Republic of the Congo. Lateral vibrations were experimentally determined using twelve proximity and eddy-current probes, positioned on each measurement plane. Th e results were analyzed using the Dasylab and R soft ware. Hence, it was observed that the vibration amplitudes of the upper guide bearing, lower guide bearing, and pivot/rotor exceeded acceptable or critical limit values of the international vibration standard for a rotating speed between 100-250 rpm. Th ese excesses can lead to rotor mass imbalances, the eccentricity of the rotor axis relative to the rotation axis of the shaft , and the deformation of the coupling shaft between the upper rotor shaft and the turbine rotor shaft. Subsequently, the means and the variances of the vibration amplitudes were evaluated and compared to the reference values of the international standard. Th e results of the compliance analysis revealed statistically signifi cant diff erences between the measured amplitudes and the reference values. Th us, it indicates deviations from international specifi cations.

The goal of this study is the introduction and experimental assessment of a sequential probability ratio test framework for vibration-based structural health monitoring. This framework is based on a combination of binary and multihypothesis versions of the statistically optimal sequential probability ratio test and employs the residual sequences obtained through a single stochastic time series model of the healthy structure. The full list of properties and capabilities of the sequential probability ratio test is for the first time presented and explored in the context of vibration-based damage diagnosis. The approach postulated in this framework is shown to achieve early and robust damage detection, identification (classification), and quantification based on predetermined sampling plans, which are both analytically and experimentally compared and assessed. The framework’s performance is determined a priori via the use of the analytical expressions of the operating characteristic an...

This work aims at the experimental assessment of a number of statistical time series methods for Structural Health Monitoring (SHM). The main features and operation of the employed non-parametric and parametric methods are briefly reviewed. Their performance is subsequently assessed via laboratory experiments pertaining to damage detection and identification on a thin aluminum plate structure. The results of the study demonstrate the potential and effectiveness of the statistical time series SHM methods.

Częstą przyczyną drgań w pompach wirowych są pulsacje ciśnienia wywołane oddziaływaniem wirnika i kierownicy.
Mają one charakter periodyczny. Mogą przenosić się na tarcze wirnika i prowadzić nawet do ich uszkodzeń.
Wygodnym narzędziem określenia zbioru częstotliwości łopatkowych charakteryzujących te pulsacje jest diagram
przejścia. Pulsacje ciśnienia mogą wywołać rezonans strukturalny związany z częstotliwościami własnymi elementów
pompy bądź rezonans akustyczny w elementach rurowych. Znajomość częstotliwości łopatkowych ułatwia diagnostykę
drgań pompy wirowej. Pulsacje ciśnienia można zmniejszyć bądź przez stoczenie wirnika bądź skośny kształt
krawędzi łopatek wirnika lub kierownicy.

Une méthodologie de dimensionnement en amortissement d'une caisse automobile est proposée. Elle utilise les sensibilités des taux d'amortissement modaux aux perturbations de masse, raideur, et amortissement des composants de la caisse. Un algorithme classique d'optimisation par gradient permet alors de maximiser son amortissement.

Physical interactions with socially assistive robots (SARs) positively affect user wellbeing. However, haptic experiences when touching a SAR are typically limited to perceiving the robot’s movements or shell texture, while other modalities that could enhance the touch experience with the robot, such as vibrotactile stimulation, are under-explored. In this exploratory qualitative study, we investigate the potential of enhancing human interaction with the PARO robot through vibrotactile heartbeats, with the goal to regulate subjective wellbeing during stressful situations. We conducted in-depth one-on-one interviews with 30 participants, who watched three horror movie clips alone, with PARO, and with a PARO that displayed a vibrotactile heartbeat. Our findings show that PARO’s presence and its interactive capabilities can help users regulate emotions through attentional redeployment from a stressor toward the robot. The vibrotactile heartbeat further reinforced PARO’s physical and social presence, enhancing the socio-emotional support provided by the robot and its perceived life-likeness. We discuss the impact of individual differences in user experience and implications for the future design of life-like vibrotactile stimulation for SARs.

Presentation overview of Failure analysis of a helicopter rotor system. This presentation was performed by Md. Shahin Hossain (199012), and me Shariful Islam (199024). Department of Materials and Metallurgical Engineering at Dhaka University of Engineering and Technology, Gazipur.

This research paper on a problem that has persisted over the years in heavy-duty engines is commonly known as "pin tick." It refers to a condition whereby there is very significant wear of the rod bushing. The problem was observed in various heavy-duty engines, whereby wear exceeded 30 μm with noticeable play between the rod bushing and pin. With previous attempts to solve the problem—like implementing roundness specifications for the pin bore—the problem still prevails. Testing procedures for noise, vibration, and hardness were carried out to understand the challenge completely and to arrive at a solution. All these tests pointed to a lubrication-related root cause of the problem. Our research in this field has been largely focused on evaluating the performance of a new chevron-grooved bushing design. The validation program included a full-scale CAE simulation, proof-of-concept tests, and other design and process validation tests. This paper discusses in detail the methodology and findings from this investigation in finding a sustainable solution to arrest rod bushing wear in heavy-duty engines.

This paper examines the theoretical possibility of producing boundless electrical energy by way of acceleration of electromagnetic coils, with emphasis on the possibility of constructing a perpetual motion machine. We assess the mechanisms of electromagnetic induction, motion of coils and laws of physics in general to answer the question; is it possible to deploy such a system for producing limitless energy? By employing mathematical modeling, corroborated by the laws of physics as well as the laws of thermodynamics, we maintain that while electromagnetic coil acceleration will yield some electricity, output heat due to energy losses as well as energy conservation law renders the prospect of obtaining infinite electricity from such a system impossible.

In this development, a modal analysis of free-free and fixed-free beams undergoing free vibration is investigated in Ansys APDL (15.0) based on Finite Element Analysis (FEA) and analytically using Euler-Bernoulli beam theory. Three different materials including: Steel, Aluminum, and Copper are considered in this study. The numerical results obtained from FEA using Ansys are compared with the analytical solution based on Euler-Bernoulli beam formulation and a good agreement is found with a correlation factor (2) greater than 0.99. In addition, the natural frequencies for the free-free beam are found to be much higher than those of the cantilever beam and the natural frequencies enlarge by increasing the mode number in both of the cases.

In this work a novel wavelet-fuzzy logic approach to structural health monitoring is proposed based on wavelet transform theory and fuzzy logic technology. The proposed method combines the effectiveness of the Wavelet Packet Transform (WPT) as a tool for feature extraction and the capabilities of fuzzy sets to model vagueness and uncertainty. Two stages of operation are considered: pattern training and health monitoring. Pattern training is concerned with the determination of fuzzy sets based baseline patterns representing health condition states for which training data are available. Health monitoring is concerned with the classification of new data into the different structural health states. This classification problem is solved based on determining degrees of membership values to each one of the previously defined fuzzy patterns. In order to demonstrate the effectiveness and viability of the proposed approach, the method was applied to data collected from an experiment involving repeatedly impact excitations of an aluminum cantilever beam. Different damage cases in the beam where emulated by adding a lumped mass at different locations. The measured vibration response data provided by six accelerometers were analyzed. Results show that the method is effective in classifying the different damage cases.

In this arrangement motion is transmitted between the co-axial shafts of different diameters. The synthesis of this mechanism reveals that the no. of pins used in this arrangement should be even ,..2,4,6,8. If more pins used motion will be smoother, but increase in no. of pins not at the cost of strength of shaft. Pins are fixed(may be permanent of temporary) in the drilled holes at the both shaft ends due to which motion is transferred .elbow pins or Z-pins or link used for this arrangements. The bent angle for the all pins are given very precisely , holes drilled very accurately & the axis of both the shafts must be co-axial. Proposed arrangement used for any set of diameters with any profile of shafts but the shafts must be co-axial and having rotational motion along the common axis. Working of this arrangement is very smooth & use very effectively with very minimum amount of power losses.

The thermodynamic properties of three halocarbon molecules relevant in atmospheric and public health applications are presented from ab initio calculations. Our technique makes use of a reaction path-like Hamiltonian to couple all the vibrational modes to a large-amplitude torsion for 1,2-difluoroethane, 1,2-dichloroethane, and 1,2-dibromoethane, each of which possesses a heavy asymmetric rotor. Optimized ab initio energies and Hessians were calculated at the CCSD(T) and MP2 levels of theory, respectively. In addition, to investigate the contribution of electronically excited states to thermodynamic properties, several excited singlet and triplet states for each of the halocarbons were computed at the CASSCF/MRCI level. Using the resulting potentials and projected frequencies, the couplings of all the vibrational modes to the large-amplitude torsion are calculated using the new STAR-P 2.4.0 software platform that automatically parallelizes our codes with distributed memory via a fam...