Vibrations

LAPAN IPB/LAPAN-A3 satellite’s payloads consist of many electronic, mechanical, and optical parts or components. In terms of durability, these components are quite sensitive to vibration. To avoid failure due to the vibration, things we can do is to minimize or reduce the vibration of the launch vehicle in payloads, by making damper system that can reduce or minimize vibration in payloads. The method used in this damper system is to use wire rope isolators. This method was chosen because it is easier in computation and installation of the use than synthetic rubber dampers. The working principle of spring is to convert the movement of the vibration that occurs into oscillation. Oscillation will reduce the acceleration due to the response time of the spring takes longer though there is no energy is absorbed. Based on the calculations, the wire ropes in compression position obtained W = 42.91N and Kv = 155.57kN/m with total of 16 springs, produce performance fn = 14.42Hz, and Ao = 0.08g. As for the position of shear or spring roll, W = 19.6N and Kv = 17,76kN/m with a total of 15 springs, produce output performance fn = 12,87Hz and Ao = 0,1g. Ao value is quite safe for parts/components of the charge. The result of this calculation is an early prediction of the design and configuration of LAPAN-IPB/LAPAN-A3. Further testing needs to be done at the sub-systems level in order verification prior to the implementation and at satellite level testing with the expectation that LAPAN-IPB/LAPAN-A3 payload components are capable to receive vibration loads during launch.

Predicting how the fingertip will mechanically respond to different stimuli can help explain human haptic perception and enable improvements to actuation approaches such as ultrasonic mid-air haptics. This study addresses this goal using high-fidelity 3D finite element analyses. We compute the deformation profiles and amplitudes caused by harmonic forces applied in the normal direction at four locations: the center of the finger pad, the side of the finger, the tip of the finger, and the oblique midpoint of these three sites. The excitation frequency is swept from 2.5 to 260 Hz. The simulated frequency response functions (FRFs) obtained for displacement demonstrate that the relative magnitudes of the deformations elicited by stimulating at each of these four locations greatly depend on whether only the excitation point or the entire finger is considered. The point force that induces the smallest local deformation can even cause the largest overall deformation at certain frequency intervals. Above 225 Hz, oblique excitation produces larger mean displacement amplitudes than the other three forces due to excitation of multiple modes involving diagonal deformation. These simulation results give novel insights into the combined influence of excitation location and frequency on the fingertip dynamic response, potentially facilitating the design of future vibration feedback devices.

A rt u ro M a rt ín e z R od rí g ue z 2 y Oscar Llanes Guerra 3 RESUMEN. La Cosecha de café con el auxilio de medios mecánicos se hace impracticable para la inmensa mayoría de los productores de café en el mundo, debido fundamentalmente a que, por lo general, en el momento de la cosecha las plantas contienen frutos en todos sus estadios de maduración y no han podido ser desarrollados equipos que garanticen altos indicadores de selectividad en el desprendimiento de los frutos durante la operación de cosecha. En un primer estudio (Symposio do Café do Brasil. EMBRAPA), se efectuó un análisis modal de distintas configuraciones del sistema fruto-pedicelo-pedúnculo del café, a partir del cual se confirmó el pronóstico de lograr el desprendimiento selectivo de los frutos (desprendimiento de un alto porcentaje de frutos maduros y bajo porcentaje de frutos verdes) si se seleccionan las frecuencias de vibración de las máquinas que emplean este principio de trabajo, en el entorno de un modo de vibración "en contrafase" del sistema fruto-pedicelo-pedúnculo. Ese primer análisis modal comprendió el estudio de los primeros 12 modos de vibración del sistema, lo cual fue suficiente para el análisis de configuraciones de un fruto por pedúnculo, pero resultó insuficiente para un análisis con mayor profundidad del comportamiento de configuraciones con dos y tres frutos por pedúnculo. En el presente trabajo se efectúa, mediante la simulación con el empleo de herramientas CAD-3D y programas de análisis por elementos finitos, un análisis modal abarcador de los primeros 25 modos de vibración del sistema fruto-pedicelo-pedúnculo del café (coffea arabica) variedades "Caturra Rojo" y "Caturra Amarillo". Como resultado del estudio se pudieron diferenciar cuatro variantes de modos de vibración en contrafase del sistema fruto-pedicelo-pedúnculo, pudiendo recomendarse el modo con mejores expectativas para la cosecha selectiva del café.

• Multi-objective optimization of composite plates is performed using lamination parameters. • Fundamental frequency, buckling load and effective stiffness metrics are maximized. • Pareto-optimal solutions are determined considering various problem cases. • A valuable insight has been provided on conformity/conflict of multiple objectives. • Presented methodology can be utilized for the optimal design of laminated plates.

Due to the nonlocal Euler–Bernoulli elastic beam theory, the effects of rippling deformation on the bending modulus and the structural bending instability of a single-walled carbon nanotube (SWCNT) are investigated. The nonlinear vibrational model of a cantilevered SWCNT is solved using the perturbation method of multiscales. The nonlinear resonant frequency and the associated effective bending modulus of the carbon nanotube (CNT) are derived analytically. The effects of the nonlocal parameter, the external harmonic force, and the diameter-to-length ratio on the effective bending modulus are discussed widely. Moreover, the model can predict special kind of structural instability due to the rippling deformation called rippling instability. The results show that the nonlocal theory forecasts larger values for the effective bending modulus compared with the classical beam theory, especially for the stubby CNTs. Meanwhile, the rippling instability threshold will move to the higher value...

The solid particle erosion (SPE) performance of three different transparent materials, polycarbonate solid sheet, plexiglass (Polymethylmethacrylate (PMMA), and laminated glass was investigated. Erosion tests were performed under different impact angles (20°, 30°, 45°, 60°, and 90°) and impinging velocities (75, 150, and 200 m/s). As erodent particles, alumina (Al2O3) with 52 µm average diameter and silicon carbide (SiC), particles with two different dimensions (71, and 348 µm in diameters) were used. The results showed that polycarbonate specimens outperformed the other tested samples regardless of impact velocity and impinging angle conditions. When the erosion resistance of samples at 90° and 75 m/s is taken into consideration, the polycarbonate sheet was found to be at least 14 times more erosion resistant compared to plexiglass, and 23 times more resistant than the laminated glass materials. In addition, polycarbonate exhibited an incubation behavior at lower impact velocity, and with SiC erodent.

An operating mechanic system can experience excessive vibrations if the forces acting in this system close to the natural frequency. Excessive vibration can cause damage, so it needs to be reduced. One of the ways to reduce excessive vibration, especially in system which vibrate with a single frequency, is adding DVA (Dynamic Vibration Absorber). In this study, there were simulations of non-DVA and T-DVA (Triple Dynamic Vibration Absorber) systems which DVA is arranged in series in the main system to get the RMS and amplitude of vibration response. This study used excitation in configuration model in the form of unbalance mass. Configuration model was derived, so, it was obtained equation variable state. From the equation, it was simulated by software. From this simulation, it could be concluded that DVA addition where cantered main mass of gravity center was able to reduce the vibration in yu rms dva distance system of 0.8182 m, 0.5628 m, and 0.2046m, yu rms dva mass system was 0.8911 m, 0.5242 m, and 0.3713m, and the respond result decreased, so, excitation frequency exceeded and known the natural frequency of the system.

Ethanol blended petrol is one of the alternate fuel proved to be used for petrol engines. The ethanol blending will help the energy economy of the country and reduce vehicle emissions.present research in India has tested ethanol blended petrol (biofuel) up to 5%. The country is fast moving towards green energy and a great advantage by bioethanol blending from agricultural product with petrol will identify one of the area for economic development of the country. An experiment was conducted to optimise the CR for single cylinder 4 stroke petrol engine for different blends of ethanol with petrol. VCR engine with eddy current dynamometer setup was used for testing the blends of E5, E7.5 & E10 in different CR. The Brake power and compression ratio for petrol and different blends resulted among all the blends tested (7.5% ethanol +92.5% petrol) is on par with pure petrol in developing brake power with lower BSFC.. The Brake power and compression ratio for petrol and different blends of ethanol tested it is observed that among all the blends tested ,7.5% blend is on par with pure petrol at all compression ratio

We hypothesized that short-term exposure of mice to vibration within a frequency range thought to be near the resonant frequency range of mouse tissue and at an acceleration of 0 to 1 m/s(2) would alter heart rate (HR) and mean arterial pressure (MAP). We used radiotelemetry to evaluate the cardiovascular response to vibration in C57BL/6 and CD1 male mice exposed to vertical vibration of various frequencies and accelerations. MAP was consistently increased above baseline values at an acceleration near 1 m/s(2) and a frequency of 90 Hz in both strains, and HR was increased also in C57BL/6 mice. In addition, MAP increased at 80 Hz in individual mice of both strains. When both strains were analyzed together, mean MAP and HR were increased at 90 Hz at 1 m/s(2), and HR was increased at 80 Hz at 1 m/s(2). No consistent change in MAP or HR occurred when mice were exposed to frequencies below 80 Hz or above 90 Hz. The increase in MAP and HR occurred only when the mice had conscious awarenes...

A new electromagnetic rotary mechanism utilizing a friction drive is proposed. An electromagnetic vibration excited on a permanent magnet is converted to a rotary movement through a frictional force. A trial motor, composed of a magnet rotor with inclined legs and an excitation coil, was fabricated and successfully operated. A no-load revolution speed up to 400 rpm and a reversible rotation were achieved.

Rotationally periodic structures are commonly employed in many technological applications, e.g. satellite antennae, rotors and turbine bladed-disks. The periodic arrangement of identical substructures implies that, for any eigenmode, all the substructures exhibit the same vibration amplitude with different phases. This feature can be exploited in the dynamic analysis, enabling significant simplifications . An important issue concerning rotationally periodic structures is to control their vibrations. Some traditional typologies of passive damping devices have been proposed, essentially obtained by adding frictional dampers and viscoelastic damping treatments at the local substructure level. More recently, proposed to employ piezoelectric actuators, which turn out to be very suitable when size and weight constraints on the controlled structure prevent from the use of the traditional actuators. In this paper, a broadband vibration control for rotationally periodic structures, composed of many piezoactuated beams clamped to a ring basement, is investigated. It is obtained by connecting the piezoelectric actuators to purely passive periodic electric networks . A homogenization technique is employed to derive a simple analytical model of the electromechanical coupled structure, useful both for the dynamical analysis and for the design and simulation of the passive vibration control scheme. The simulation results show that the proposed passive control technique is effective for the multimodal vibration damping of rotationally periodic structures.

It was suggested earlier (2005) that it is possible that in the brain occur sets of mobile charge carriers which may undergo phase transitions between the plasma (classical or quantum) and the state where they interact individually. This article, referring to Prof. Włodzimierz Sedlak’s remarks on the brain and consciousness presents a broadening of the hypothesis mentioned earlier. The brain is considered a vast collection of nanometer size (from a few to several tens of them) units which, as a result of the changes in the properties of the atomic lattice and the concentration and temperature of mobile charge carriers, undergo phase transitions. As a result, various dynamical sets of these units are created. Those of them that are in the plasma state in a given moment are called dynamic plasma constellations of the brain. As the heuristic means, the results of nanoplasmonics (belonging to the area of biology inspired by physics and technology) have been used here. 
If the plasmons are the real dynamical constituents of the brain, a broad perspective would be opened, e. g. various types of oscillator interactions between separate nano-units of plasma may be included in the attempts at elucidation of the mechanisms of the function of the brain.
In the plain of the philosophical reflection on the progress of the knowledge of the brain, an outline of the evolution of the paradigms of the structure and function of the brain was presented. Its beginning phase (in substantial measure philosophical) marks the stoic concept of the rational, active, and continuous substrate (pneuma). Later ones, which were taken here into account are the pneumato-hydraulic concept of the XVII and XVIIIth centuries, electrical and electrochemical (XIX and XXth centuries), and the connectomic one (End of the XX and beginning of XXI centuries). All of them originated and developed in the context of the progress made in other sciences (such as anatomy, histology, cytology, biochemistry, computer sciences, etc.). The concept proposed by R. Descartes and the contemporary computer-assisted study of the brain are exemplary cases of such influence.  Another feature of this paradigmatic evolution is paying attention to the smaller and smaller units of the organization of the brain, elucidation of growing complexity of connections and dependencies between the various levels of structural and functional organization of the brain. The approach presented here is essentially related to the physics of solid state, nanosciences, and nanotechnologies. The smallest units are the electrons and holes, as well as the higher-order structures supervening them.

Abstrak - Getaran atau vibrasi yang terjadi pada sebuah kendaraan yang sering kita gunakan akan menimbulkan ketidaknyamanan. Tidak hanya itu, getaran yang ditimbulkan secara berlebihan pada kendaraan cepat atau lambat akan menyebabkan kerusakan-kerusakan pada komponen-komponen yang terdapat pada kendaraan. Hal ini tidak berbeda jauh dengan getaran yang ditimbulkan pada suspensi yang berlebihan, tentu akan merusak sistem suspensi itu sendiri. Oleh karena hal tersebut, tujuan dari penelitian ini adalah menganalisa jenis-jenis kerusakan yang diakibatkan oleh vibrasi pada sistem suspensi kendaraan roda empat (mobil), supaya adanya tindak lanjut sebagai evaluasi dalam memproduksi kendaraan untuk menghasilkan kendaraan yang berkualitas serta memberikan keamanan dan kenyamanan. Dan akan sangat penting kiranya untuk mendeteksi getaran dan kerusakan yang ditimbulkan dari vibrasi (getaran), dimana selanjutnya dapat dilakukan usaha untuk meminimalisasi getaran atau vibrasi yang terjadi. Kesimp...

Abstrak -Getaran atau vibrasi yang terjadi pada sebuah kendaraan yang sering kita gunakan akan menimbulkan ketidaknyamanan. Tidak hanya itu, getaran yang ditimbulkan secara berlebihan pada kendaraan cepat atau lambat akan menyebabkan kerusakan-kerusakan pada komponen-komponen yang terdapat pada kendaraan. Hal ini tidak berbeda jauh dengan getaran yang ditimbulkan pada suspensi yang berlebihan, tentu akan merusak sistem suspensi itu sendiri. Oleh karena hal tersebut, tujuan dari penelitian ini adalah menganalisa jenis-jenis kerusakan yang diakibatkan oleh vibrasi pada sistem suspensi kendaraan roda empat (mobil), supaya adanya tindak lanjut sebagai evaluasi dalam memproduksi kendaraan untuk menghasilkan kendaraan yang berkualitas serta memberikan keamanan dan kenyamanan. Dan akan sangat penting kiranya untuk mendeteksi getaran dan kerusakan yang ditimbulkan dari vibrasi (getaran), dimana selanjutnya dapat dilakukan usaha untuk meminimalisasi getaran atau vibrasi yang terjadi. Kesimpulan dari penelitian ini yaitu pertama vibrasi atau getaran pada sistem suspensi akan menimbulkan kerusakan dengan kategori cacat lokal dan cacat terdistribusi. Kedua, vibrasi atau getaran akan menimbulkan kerusakan pada sistem suspensi, begitu juga sebaliknya kerusakan akan menimbulkan getaran. Serta ketiga, untuk menganalisa kerusakan akibat getaran atau vibrasi dapat dibantu oleh beberapa alat standar seperti vibration meter, vibration analyszer, Shock Pulse Meter, dan osciloskop.

This study focuses on leveraging CNC technology to enhance the face milling procedures' surface quality. Determining the success of machining outputs depends heavily on measuring surface roughness. In order to create an intelligent model for forecasting surface roughness, the study gathered total overall vibration data in the X, Y, and Z directions throughout face milling operations. The model's effectiveness underwent a careful evaluation and assessment. As a result of predicting surface roughness based on total vibrations in all three dimensions, the authors' intelligent approach represents a substantial advancement. This breakthrough has the potential to redefine efficiency and profitability standards, revolutionize production processes, and optimize resource allocation. A number of models, including polynomial, decision tree, random forest, and ANFIS models, were created to forecast surface roughness. After comparing these models to other machine learning models, the evaluation revealed that the ANFIS model had a 98% prediction accuracy. This indicates that ANFIS is a better model than other models for estimating surface roughness, particularly when using information from machine tool vibrations in all three directions. The upcoming adoption of these cutting-edge technologies is anticipated to transform a number of industries, underlining the authors' ground-breaking contributions to the trajectory of industrial advancement.

CNC Machining stands as a pivotal process for attaining precise dimensions and surface roughness in component manufacturing. Within this realm, the vibration of CNC machine spindle bearings significantly impacts the quality of machined parts. This study focuses on face milling aluminum AA6101 T65 alloy, aiming to assess surface roughness via machine vibrations. The study identified the spindle bearing as the primary source of vibration in the CNC milling machine, exerting a significant influence on surface roughness. Vibrational features, including RMS (root-mean-square) and FFT (Fast Fourier Transform) analysis, are extracted, and frequency normalization is applied. Utilizing conversion factors, corresponding peak amplitudes, termed vibrations, are noted. Subsequently, predictive models for surface roughness are developed, incorporating bearing vibrations in frequency domain techniques like ball pass frequency outer race, ball pass frequency inner race, and ball spin frequency BSF as critical inputs. Python machine learning techniques, including linear, polynomial, tree, random forest, and decision tree regression models, are utilized. Notably, the polynomial regression model stood out, exhibiting high accuracy with an R 2 value approaching 1 and an RMSE value nearing 0. This research underscored the significance of understanding and mitigating vibrations in CNC milling processes, offering practical insights for optimizing surface roughness. The predictive models developed enhanced the efficiency of machining operations, contributing to advancements in precision manufacturing. This work demonstrated the integration of vibration analysis, frequency domain techniques, and machine learning in addressing surface quality challenges, paving the way for improved machining outcomes in diverse industrial applications.

The three building blocks of nature are mass, energy and information. All of reality exists both as particles and waves and everything is interconnected metaphorically as partners dancing to music within a universal quantum field of "divine eros." Physics is now considered a science of relationships rather than just a science of the structure
and behavior of matter. Quantum physicists now confirm what ancient philosophers were trying to articulate: relationship is actually a more accurate way to describe the core operating actions of reality itself. Quantum biologists and evolutionary scientists seem to concur that at the center of all things is a deep conversation, a dynamic back-and-forth sharing of information operating as a coherent resonance of quantum
acoustic/electromagnetic/vibration frequencies that are omnipresent and guiding multiple activities in both cosmic and life processes. •
• The Cosmos should not be seen as a giant machine, nor as a versatile computer, but rather like a musically inspired and fine-tuned electro/gravitational process in which we are waves resonating in a harmonious infinite symphony.
• Everything in consciousness connects and interacts via resonances of individual wavelength frequencies, through “The Acoustic Quantum Code of Resonant Coherence” of Dirk Meijer, unified in “the joy of the cosmic dance” of Merton, and within the singularity of the still point of Eliot: “Except for the point, the still point, there would be no dance, and there is only the dance.”

This paper presents a methodology for the reduction of Dynamic Mixed Finite Element Models (DM-FEMs) based on the use of a sub-structuring primal methods adapted to such models. We implement a DM-FEM for Kirchhoff-Love (KL) thin plates using the Hellinger-Reissner (HR) variational mixed formulation adapted to dynamic, and give a quick insight of its convergence. This model uses both displacement and generalized stress fields within the plate, obtained as a primary result, but the numerical size of the model is bigger than with a primal displacement model. Thus we choose to offset this complication by reducing the model with a totally new sub-structuring reduction method, especially adapted to DM-FEMs. The aim of our method is to adapt sub-structuring reduction methods commonly used for primal displacement FEM only (such as Craig & Bampton method) and split the reduction of the two fields. With these displacement methods, the whole structure is splitted into few smaller ones, and each of them is condensed with eigenmodes of the sub-structure and static connections between them. The principle of our method is to build, for each sub-structure, a reduced basis for the displacements according to the existing method, and a projection of the primal basis for the stresses. A new reduced basis for the whole mixed model is then built up exclusively with modes taken from the primal model. That method reduces significantly the number of degrees of freedom (DOF), and keeps the properties and advantages of the mixed formulation.

This paper presents a methodology for the reduction of Dynamic Mixed Finite Element Models (DM-FEMs) based on the use of a sub-structuring primal methods adapted to such models. We implement a DM-FEM for Kirchhoff-Love (KL) thin plates using the Hellinger-Reissner (HR) variational mixed formulation adapted to dynamic, and give a quick insight of its convergence. This model uses both displacement and generalized stress fields within the plate, obtained as a primary result, but the numerical size of the model is bigger than with a primal displacement model. Thus we choose to offset this complication by reducing the model with a totally new sub-structuring reduction method, especially adapted to DM-FEMs. The aim of our method is to adapt sub-structuring reduction methods commonly used for primal displacement FEM only (such as Craig & Bampton method) and split the reduction of the two fields. With these displacement methods, the whole structure is splitted into few smaller ones, and each of them is condensed with eigenmodes of the sub-structure and static connections between them. The principle of our method is to build, for each sub-structure, a reduced basis for the displacements according to the existing method, and a projection of the primal basis for the stresses. A new reduced basis for the whole mixed model is then built up exclusively with modes taken from the primal model. That method reduces significantly the number of degrees of freedom (DOF), and keeps the properties and advantages of the mixed formulation.

Theoretical investigations into the capabilities of a coaxial inertial drive with various operating modes for vibratory conveyors and screens are conducted in the paper. The coaxial inertial exciter is designed with one asynchronous electric motor and the kinematically synchronized rotation of two unbalanced masses. Three variants of angular speeds ratios, namely ω2/ω1 = 1, ω2/ω1 = –1, and ω2/ω1 = 2, are considered. Based on these relations, the circular, elliptical, and complex motion trajectories of the working members are implemented. In the first two cases, single-frequency harmonic oscillations take place. In the latter case, the double-frequency periodic oscillations are excited. The dynamic behavior of the motor’s shaft during its running-up and running-out is considered. The influence of the inertial parameters of the unbalanced rotors and the relative phase shift angle between them on the elliptical trajectories of the vibratory system’s mass center motion is investigated. ...

The paper concerns the wide range of strategies used to protect structures against man-made dynamic excitation. The most popular approaches applied worldwide are compared, and the main differences and similarities are summarized. The literature studies are supported by the results of the measurements performed on different types of real structures, which are sensitive and insensitive to the dynamic load. To make the conclusions more general, various types of excitation forces are examined (long-term and short-term excitations, traffic load, and loads resulting from geotechnical works). The main issue raised in the paper is the problem of unequivocal and accurate assessment of the potential structure damage, based on the different legislations. It can be seen that the application of different codes can even result in opposite conclusions about the safety of the structure.

The limitations of thermal, vibration, or electrical monitoring of electric machines such as false indications, low sensitivity, and difficulty of fault interpretation have recently been exposed. This has led to a shift in the direction in research towards applying new techniques for improving the reliability of condition monitoring. With the changing environment, the purpose of this article is to provide an overview of the recent trend in the industrial demand and research activity in condition monitoring technology. The new developments in insulation testing, electrical testing, flux analysis, transient analysis, and fault prognostics are summarized. The future challenges and recommendations for future work for the new technologies are also stated to support researchers target research/development efforts according to industrial needs.

Oil seals are commonly used in high speed multistage compressors. If the oil seal ring becomes locked up against the fixed portion of the seal, high oil film crosscoupled stiffnesses can result. A method of analysis for determining if the oil seals are locked up or not is discussed. The method is then applied to an oil seal in a compressor with subsynchronous vibration problems.

Rotating machinery acceptance parameters in terms of vibration and protection is one of the key considerations in detailed engineering and design process. For these activities, API standards are used normally in oil and gas industries. For centrifugal pumps, API 610 and 670 may mandate too stringent requirement for particular type of pumps in terms of acceptance criteria irrespective to actual duty of pump. There is a growing desire for using hydrodynamic bearings irrespective to energy level of pump in a general believe that they have virtually infinite life span. The acceptance criteria during shop tests as mandated by API 610 has not recognized the bearing and foundation flexibility. This is a potential grey area for machinery engineers from end user/contractor engaged in detailed engineering. The objective of this article is to provide the insights of the aspect.

ANCRP or Artificial Noise convertor and reducer panel is a device that may be helpful in reducing the noise of the urban areas that mainly contains the voices and vibrations generated due to the artificial sources as result of human activities and actions. As the noise above a certain level (thresh hold) on decibel scale is harmful for the living life present in that area, both psychologically and physically if this interaction lasts for a longer period may cause serious and permanent damage to that interacting body. These ill-effects could be avoided by reducing and finishing the noise. These demands support the research in the areas of noise pollution control and portable energy generation methods. In this scope, ANCRP become a strong candidate for pollution control, energy generation and storage in future applications. This article describes the use of crystalline polymers in order to reduce noise and harvest energy from unwanted noise capable of producing dander to health of living creature in surrounding areas.

This thesis deals with the optimization of the laundry load distribution within front loaded washing machines in order to avoid vibration noise and, in consequence, increase the performance and duration of such systems. The washing machine is programmed to follow several cycles in order to clean the laundry. The higher levels of vibration are reached when the motor executes the drying cycle where the laundry will spin at a very high speed in order to remove the water by using the generated centrifugal force. The aim of this thesis is to find a method which, when used, obtains a new distribution scheme that will evenly distribute the laundry load. This scheme will reduce the vibration with a low cost for the implementation since the change will be made only in the software of the system. In order to evaluate a possible solution scheme, a hardware-in-the-loop (HIL) set up was created. The HIL set up makes possible to avoid the complex modeling of the system as the washing machine itself will run each scheme and give a real time feedback of the unbalance. To improve the load distribution a novel approach is explored by using Evolutionary Algorithms that have been proved to solve problems with similar complexity involving a high number of variables. A scheme was obtained after the execution of the evolutionary algorithm that achieved a better performance of 12% less unbalance with 9.8% lower standard deviation than the current distribution scheme used commercially. With these results the validation of this method to obtain optimal distribution schemes is demonstrated.

The paper presents the natural frequencies shift of a Warren truss with seven elements in the case that members of the structure are weakened by considering that the modulus of elasticity with a lower value. Taking into consideration that the slenderness ratio has a constant value and the transverse section of the truss bars is changed, the relative frequency shift for the first seven vibration mode were calculated by using the values obtained from numerical modal analysis. The conclusions reveal the fact from the dynamic behavior of the structure it can be obtained templates to identify the weakened truss bar of the structure.

This paper proposes an analytic relation for the deflection of a cantilever beam with a transverse crack subjected to dead load. The mathematical relation is deduced involving the decreased capacity of the beam to store energy, which is in direct relation with the crack position and depth. Eventually, the validity of the relation is proved by means of the finite element method.

This paper presents a method to find the severity of a crack for cantilever beams that can be used to estimate the frequency drop due to the crack. The severity is found for the crack located at the location where the biggest curvature (or bending moment) is achieved. Because the fixing condition does not permit a symmetrical deformation around the crack, the apparent severity is smaller as the real one. The latter is found by the estimated value of the trend-line at the fixed end, it being constructed on points that consider the crack position (equidistant points in the proximity of the fixed end) and the resulted deflections.

This paper compare two methods to determine the severity of a damage occurring in cantilever; the first method is well-known in the literature and base on an approach from fracture mechanics, while the second is contrived by the authors and base on the transversal deflection under small loads. First the paper demonstrate the relation existing between the stiffness reduction due to damage (i.e. the value of the transversal deflection) and the change of the natural frequencies, exemplified for three shapes of the transversal cross-section. It is proofed that the relation is valid for all three cases, square, hexagon and circle, the damage depth being accurate determined. Afterwards, the results are compared with that provided by numerous researchers which used the fracture mechanics approach; a good concordance can be found, with the mention that the method developed by us is more accurate. This is justified by the fact that our method does not introduce empirical relations, being bas...

Abstract:-This paper presents the researches made by the authors in order to develop an algorithm and method to localize damages in beams using vibration measurement. The chosen type of beam was the cantilever one, for which a database containing the first ten natural frequencies in undamaged state was realized. Afterwards, eight points relevant for the characterization of the beam's dynamic behavior were determined by analytical calculus. The database was completed with the first ten natural frequencies of the beam damaged ...

We introduce in this paper an intelligent system that automatically detects the damage in cantilever beams called AgentMec. This agent is creating its knowledge using a database with the first ten natural frequencies of the beam damaged at predetermined points. Using the ...

Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Board's recognized objectivity and understanding of modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state, and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO.

Cet exposé présente les résultats de l'article [3] au sujet des ondes progressives pour l'équation de Gross-Pitaevskii : la construction d'une branche d'ondes progressives non constantes d'énergie finie en dimensions deux et trois par un argument variationnel de minimisation sous contraintes, ainsi que la non-existence d'ondes progressives non constantes d'énergie petite en dimension trois.

The structure and dynamics of atomic oxygen adsorbed on Ag(410) and Ag(210) surfaces has been investigated using density functional theory. Our results show that the adsorption configuration in which O adatoms decorate the upper side of the (110) steps forming O-Ag-O rows is particularly stable for both surfaces. On Ag(210), this arrangement is more stable than other configurations at all the investigated coverages. On Ag(410), adsorption on the terrace and at the step edge are almost degenerate, the former being slightly preferred at low coverage while the latter is stabilized by increasing the coverage. These findings are substantiated by a comparison between the vibrational modes, calculated within density-functional perturbation theory, and the HREEL spectrum which has been recently measured in these systems.

The paper presents problems related to road safety in terms of the development of the concrete barriers system, dispersing energy of car collision on the roads with high traffic and high accident risk. Particular attention was paid to barriers' basic parameters -weight and length of the segment. The main objective of the numeric researches was to assess the qualitative and quantitative effects of the car collision with a concrete road barrier in accordance with the standard EN 1317. To the model tests a 900 kg passenger car has been used which allowed to perform TB11 test according to EN 1317-2 standard (initial velocity -100 km/h). Numerical studies were carried out for concrete segments lengths: 2, 4, 6, 8 m for two selected impact points. Detailed comparisons of simulation test results obtained for individual variants were made on the basis of the acceleration courses of selected car bodywork points, calculated indicators, the trajectory of vehicle movement after collision as well as on the basis of the behaviour of the concrete barriers.

Military vehicles are used less intensively than the civil ones, and many types of the vehicles used by the army are stored for a long time. Therefore, this type of vehicles can be used even for a dozens of years. Due to the constant development of technology, used armament and military equipment has to be adjusted to current needs. The above applies also to recovery vehicles, including field workshops. This work analyses the level of safety and comfort of the crew of the modified field workshop (Sarna II) when the vehicle is moving under various conditions. The scope of improvement included two seats inside workshop for the transportation of the crew members. Experimental research involved measuring the accelerations on the seats of the crew and the noise inside the vehicle body. The assessment was conducted on the basis of the highest value of 8-hour of the exposure to the whole body vibrations A(8). The accelerations acting on the seats were determined mainly by the kind of the r...

The paper presents problems related to road safety in terms of the development of the concrete barriers system, dispersing energy of car collision on the roads with high traffic and high accident risk. Particular attention was paid to barriers' basic parameters -weight and length of the segment. The main objective of the numeric researches was to assess the qualitative and quantitative effects of the car collision with a concrete road barrier in accordance with the standard EN 1317. To the model tests a 900 kg passenger car has been used which allowed to perform TB11 test according to EN 1317-2 standard (initial velocity -100 km/h). Numerical studies were carried out for concrete segments lengths: 2, 4, 6, 8 m for two selected impact points. Detailed comparisons of simulation test results obtained for individual variants were made on the basis of the acceleration courses of selected car bodywork points, calculated indicators, the trajectory of vehicle movement after collision as well as on the basis of the behaviour of the concrete barriers.

The paper presents problems related to dynamic loads of armoured personnel carriers design as well as soldiers located inside them. In order to assess the exposure of soldiers while overcoming terrain and engineering obstacles experimental studies were performed covering a carrier's collision with a concrete obstacle. The scope of the tests included a collision of the armoured personnel carrier with obstacle for two speeds: 6 and 12 km/h. During crash tests, anthropomorphic measurement equipment -Hybrid III 50th Male Dummy type -was used for recording the values of loads affecting the soldiers. During crash tests, two fast video cameras were used for recording motion of the carrier and obstacle's plates. The vehicle body accelerations were recorded as well.In the paper the research conditions and used measurement equipment were described. Some results of experimental studies were presented. Typical phases of motions of dummies located in driving and landing troop compartmentwere presented. The values of the carrier's body accelerations in driving and landing troop compartment were compared,displacements of barrier's segments were described. Obtained results indicated that carrier's driver is subjected to higher loads. During crash test at low velocities, the limit values were not exceeded in any analysed case.

The results of the experimental research on the influence of the special vehicle movement conditions on the body shell and the vehicle crew dynamic load will be presented in the paper. ROSOMAK Wheeled Armoured Personnel Carrier (Wheeled APC), the basic version, was the subject of the research. The research work was aimed at analysis of the dynamic loads resulting from the deterministic inputs and driving on the selected types of surfaces generating random kinematic inputs. The personnel carrier service conditions, measuring apparatus, and testing methods will be described. The vertical accelerations of the selected points of the vehicle, and deflection of the prime and second suspension of the vehicle left side were measured. The time and the acceleration RMS value spectrum charts for the selected implementations will be presented. The cumulative statistics will be shown in the form of a table. The conclusions regarding the influence of the road surface on the personnel carrier driv...

We present a new architecture for wideband vibration-based micro-power generators (MPGs). It replaces a linear oscillator with a piecewise-linear oscillator as the energy harvesting element of the MPG. A prototype of an electromagnetic MPG designed accordingly is analyzed analytically, numerically and experimentally. We find that the new architecture increases the bandwidth of the MPG during a frequency up-sweep, while maintaining the same bandwidth in a down-sweep. Closed-form expressions for the response of the new MPG as well as the up-sweep bandwidth are presented and validated experimentally. Simulations show that under random-frequency excitations, the new MPG collects more energy than the traditional MPG.

Automotive clutches are prone to rigid body torsional vibrations during engagement, a phenomenon referred to as take-up judder. This is also accompanied by fore and aft vehicle motions. Aside from driver behaviour in sudden release of clutch pedal (resulting in loss of clamp load), and type and state of friction lining material, the interfacial slip speed and contact temperature can significantly affect the propensity of clutch to judder. The ability to accurately predict the judder phenomenon relies significantly on the determination of operational frictional characteristics of the clutch lining material. This is dependent upon contact pressure, temperature and interfacial slip speed. The current study investigates the ability to predict clutch judder vibration with the degree of complexity of the torsional dynamics model. For this purpose, the results from a four and nine degrees of freedom dynamics models are compared and discussed. Subsequently, the predictions are compared with the acquired data from an automotive driveline test rig. It is shown that the complexity of the dynamic model, intended for the study of a clutch system, can be as important as the thermo-mechanical and frictional properties of the clutch friction lining material.

Take-up judder is the first rigid body torsional mode of the clutch system, which occurs during clutch engagement. This phenomenon is induced by stick-slip oscillations at the friction lining interfaces between the clutch disc and flywheel, and the pressure plate. The phenomenon is influenced by the clutch lining friction characteristics, the topography of the mating-sliding surfaces and the operational conditions during the engagement process. Therefore, the interfacial characteristics are affected by contact pressure, interfacial slip speed and surface temperature. Take-up judder causes driver and vehicle occupant discomfort, as well as gradual wear of contacting surfaces. The response frequency of the system is reported to be in the range 5-20Hz, depending on the clutch system and vehicle inertia. In this paper the measured interfacial friction characteristics together with clamp load variation (contact pressure) under different surface temperatures are included in a multidegree of freedom dynamic analysis to obtain torsional vibrations of the system, pertaining to take-up judder conditions. Such an in-depth investigation has not hitherto been reported in literature. The paper shows that take-up judder is omnipresent under all clutch engagement conditions, but its poignancy is most evident at cold surface temperatures. It is also shown that the transient judder response has a broader spectral content that is generally acknowledged.

Rolling bearings are one of the most important noise and vibration generator into mechanical constructions. Therefore, it is very important to have knowledge of the rolling element bearings influence on the level of noise and vibration in this systems. This paper deals with a basic forms for generation of vibration and noise of rolling element bearing and suggestions of vibration analysis significance of rolling element bearing for increase mechanical construction quality.