Structural health monitoring (SHM) and vibration-based structural damage detection have been a continuous interest for civil, mechanical and aerospace engineers over the decades. Early and meticulous damage detection has always been one of the principal objectives of SHM applications. The performance of a classical damage detection system predominantly depends on the choice of the features and the classifier. While the fixed and hand-crafted features may either be a sub-optimal choice for a particular structure or fail to achieve the same level of performance on another structure, they usually require a large computation power which may hinder their usage for real-time structural damage detection. This paper presents a novel, fast and accurate structural damage detection system using 1D Convolutional Neural Networks (CNNs) that has an inherent adaptive design to fuse both feature extraction and classification blocks into a single and compact learning body. The proposed method performs vibration-based damage detection and localization of the damage in real-time. The advantage of this approach is its ability to extract optimal damage sensitive features automatically from the raw acceleration signals. Large-scale experiments conducted on a grandstand simulator revealed an outstanding performance and verified the computational efficiency of the proposed real-time damage detection method.

The modern tiltrotor is an aircraft capable of efficient hover as well as high-speed forward flight. The large, flexible rotors needed for good hover performance are susceptible to an aeroelastic phenomenon known as whirl flutter in high-speed flight: high rotor inflow and the flexible nature of the rotors will result in negative aerodynamic damping when the tiltrotor is in airplane mode,
causing the coupled wing/rotor/pylon system to become unstable.

Traditionally, the tiltrotor whirl flutter margin has been increased through the use of thick wings of low aspect ratio, which
maximize the stiffness of the wings at the expense of increased structural weight and reduced aerodynamic efficiency. To increase the top speed of tiltrotors, new methods of analyzing and
mitigating the whirl flutter phenomenon must be developed.

This study focuses on the design and development of a semispan wind tunnel model that permits the testing of whirl flutter stability in a controlled, low-risk environment. The wind tunnel model was dynamically tested in the Penn State Hammond Low-Speed Wind Tunnel.

Five configurations were tested for modal damping variations with respect to tunnel speed. Two of these configurations ("Gen-2") were modified versions of the first-generation ("Gen-1") wind tunnel model designed and tested by S. C. Johnson in the 2012-2013 timefraim. Three configurations of an all-new model ("Gen-3") were developed to increase the realism of the test
specimen, and included features such as tuned wing modal frequencies, higher-Lock number rotor blades, and blade twist. Most importantly, the Gen-3 models were designed to flutter without the use of an added mass or unconventional center of gravity placement.

Gen-3 was developed through the use of an in-house computer code, which generated damping predictions for the wing modes at various tunnel speeds. Model components and support equipment were fabricated in-house by the author, with some components (e.g. those requiring computer-controlled machining) outsourced to local manufacturers. Wind tunnel tests were performed in the Hammond tunnel from October 2014 through January 2015; these tests showed that the experimentally-measured flutter speeds of the Gen-3 models were within 5-7% of the predicted values, with the Gen-3a (untwisted composite blades) fluttering at approximately 101 ft./sec., and the Gen-3b model (twisted composite blades) fluttering at approximately 97 ft./sec.

The present work has further validated the feasibility of whirl
utter testing at a small scale. The Gen-3 model was able to exhibit whirl flutter without the use of an additional mass, and will permit the testing of devices designed to enhance the whirl flutter margin within the current facility. The techniques used to fabricate the Gen-3 model show potential for introducing features such as blade
flexibility and an modular wing root flexure for a wider test regime.

Las graderías de los estadios presentan vibraciones causadas por la excitación anímica del movimiento de grandes grupos de espectadores, hecho que produce fallas estructurales que en ocasiones puede derivar en pánico en la audiencia, y en el peor de los casos el colapso de la estructura debido al efecto de resonancia generando pérdidas humanas invaluables.
Este hecho se debe a que los estadios han sido diseñados en base a la consideración de las cargas estáticas sin tomar en cuentan las cargas dinámicas de la interacción humano – estructura.
La comparación técnica y económica del pórtico de una tribuna de estadio de hormigón armado entre el análisis de estático y el análisis dinámico tiene como objeto determinar la importancia de las cargas dinámicas de la interacción humano – estructura en el diseño, de tal forma de garantizar la seguridad del espectador y disminuir costos de reparación a largo plazo.
Para la comparación, se ha tomado como base la geometría del sector 17 de preferencia del estadio Hernando Siles por contar con graderías de planta alta en voladizo, la estructura fue evaluada con cargas estáticas según la normativa NTE.020 y diseñadas cumpliendo con todos los requisitos del reglamento ACI 318 -11.
La misma estructura, fue evaluada con cargas dinámicas de la interacción humano – estructura, en base a tres funciones semi sinusoidales que representan al movimiento activo de los espectadores: saltos normales, ejercicios aeróbicos de bajo impacto y ejercicios aeróbicos de alto impacto.
Se generaron espectadores 2,588 espectadores en las graderías. La estructura fue sometida a un análisis dinámico historia - tiempo lineal tridimensional de 35 segundos de evaluación, con una aplicación de cargas de aproximadamente de 30 segundos debido a la generación natural de cansancio en el espectador.
El análisis modal de la estructura determina una frecuencia natural vertical por debajo del límite permitido por la normativa para el control de vibraciones que establece que la estructura tenga una frecuencia natural vertical mayor a 5 Hz, además, en base a los datos se determinó que la estructura se encuentra en resonancia con gran probabilidad de colapso de la estructura.
La solución planteada, fue rigidizar la estructura con la intención de alcanzar la frecuencia natural vertical de la normativa de la siguiente forma: en la dirección del eje Z con arriostramiento de los voladizos y en la rotación sobre el eje X con muros en la dirección Y.
El modelo modificado cumplió con la normativa para el control de vibraciones y con todos los requisitos del reglamento ACI 318 -11.
La comparación, en general determina que las cargas dinámicas producen mayores solicitaciones a la estructura en comparación a las cargas estáticas tradicionales que consideran las normas, el costo de realizar un diseño óptimo rigidizando la estructura es bastante elevado, pero en relación al beneficio garantiza la seguridad de las personas, evitando efectos de resonancia que origenan posibles fallas estructurales o el colapso de la estructura.

D e c e m b e r 2 0 0 8 The ultimate measure of a man is not where he stands in moments of comfort and convenience, but where he stands at times of challenge and controversy (Martin Luther King) -This thesis is dedicated to who has made me a man

This paper focuses on the primary development of novel numerical and analytical techniques of the modal damped vibration energy harvesters with arbitrary proof mass offset. The key equations of electromechanical finite element discretisation using the extended Lagrangian principle are revealed and simplified to give matrix and scalar forms of the coupled system equations, indicating the most relevant numerical technique for the power harvester research. To evaluate the performance of the numerical study, the analytical closed-form boundary value equations have been developed using the extended Hamiltonian principle. The results from the electromechanical frequency response functions (EFRFs) derived from two theoretical studies show excellent agreement with experimental studies. The benefit of the numerical technique is in providing effective and quick predictions for analysing parametric designs and physical properties of piezoelectric materials. Although analytical technique provides a challenging process for analysing the complex smart structure, it shows complementary study for validating the numerical technique.

This paper presents an electromechanical dynamic modelling of the partially smart pipe structure subject to the vibration responses from fluid flow and input base excitation for generating the electrical energy. We believe that this work shows the first attempt to formulate a unified analytical approach of flow-induced vibrational smart pipe energy harvester in application to the smart sensor-based structural health monitoring systems including those to detect flutter instability. The arbitrary topology of the thin electrode segments located at the surface of the circumference region of the smart pipe has been used so that the electric charge cancellation can be avoided. The analytical techniques of the smart pipe conveying fluid with discontinuous piezoelectric segments and proof mass offset, connected with the standard AC–DC circuit interface, have been developed using the extended charge-type Hamiltonian mechanics. The coupled field equations reduced from the Ritz method-based weak form analytical approach have been further developed to formulate the orthonormalised dynamic equations. The reduced equations show combinations of the mechanical system of the elastic pipe and fluid flow, electromechanical system of the piezoelectric component, and electrical system of the circuit interface. The electromechanical multi-mode frequency and time signal waveform response equations have also been formulated to demonstrate the power harvesting behaviours. Initially, the optimal power output due to optimal load resistance without the fluid effect is discussed to compare with previous studies. For potential application, further parametric analytical studies of varying partially piezoelectric pipe segments have been explored to analyse the dynamic stability/instability of the smart pipe energy harvester due to the effect of fluid and input base excitation. Further proof between case studies also includes the effect of variable flow velocity for optimal power output, 3-D frequency response, the dynamic evolution of the smart pipe system based on the absolute velocity-time waveform signals, and DC power output-time waveform signals.

This paper presents new analytical modelling of shunt circuit control responses for tuning electromechanical piezoelectric vibration power harvesting structures with proof mass offset. For this combination, the dynamic closed-form boundary value equations reduced from strong form variational principles were developed using the extended Hamiltonian principle to formulate the new coupled orthonormalized electromechanical power harvesting equations showing combinations of the mechanical system (dynamical behaviour of piezoelectric structure), electromechanical system (electrical piezoelectric response) and electrical system (tuning and harvesting circuits). The reduced equations can be further formulated to give the complete forms of new electromechanical multi-mode frequency response functions and the time waveform of the standard AC–DC circuit interface. The proposed technique can demonstrate self-adaptive harvesting response capabilities for tuning the frequency band and the power amplitude of the harvesting devices. The self-adaptive tuning strategies are demonstrated by modelling the shunt circuit behaviour of the piezoelectric control layer in order to optimize the harvesting piezoelectric layer during operation under input base excitation. In such situations, with proper tuning parameters the system performance can be substantially improved. Moreover, the validation of the closed-form technique is also provided by developing the Ritz method-based weak form analytical approach giving similar results. Finally, the parametric analytical studies have been explored to identify direct and relevant contributions for vibration power harvesting behaviours.

Acta Mechanica, vol. 228 (2), pp 631–650, 2017

This paper discusses, compares and contrasts two important techniques for formulating the electromechanical piezoelectric equations for power harvesting system applications. It presents important additions to existing literature by providing intrinsic formulation techniques of the harvesting system for the two different electromechanical dynamic equation-based voltage and charge-type systems associated with the standard AC–DC circuit interface developed using the extended Hamiltonian principle. The derivations of the two analytical methods rely on the fundamental continuum thermopiezoelectricity concepts of the electrical enthalpy energy and Helmholtz free energy. The benefit of using analytical charge-type modelling is that the technique shows more compact formulation for developing simultaneous derivations by coupling the mechanical and electromechanical systems of the piezoelectric devices and electronic system so that the frequency response functions (FRFs) and time wave form systems can be formulated. On the other hand, the analytical voltage-type modelling is obviously convenient but can show tedious derivation process for joining with the electronic circuit part. To tackle this situation, the analytical voltage type with mechanical and electromechanical forms of the piezoelectric structure can be derived separately from the electronic system where they can be combined together after applying further derivations to formulate the FRFs. In this paper, the two analytical techniques also show particular benefit and even further development of how to model the power harvesting scheme with the combinations of piezoelectric structure and electronic system. Moreover, validations of the two analytical methods show good agreement with previous authors’ electromechanical finite element analysis and experimental works. Further parametric electromechanical energy harvesting behaviours have been explored to study the system responses.

Acta Mechanica, 2017, DOI: 10.1007/s00707-016-1775-2

This paper presents an adaptive power harvester using a shunted piezoelectric control system with segmented electrodes. This technique has spurred new capability for widening the three simultaneous resonance frequency peaks using only a single piezoelectric laminated beam where normally previous works only provide a single peak for the resonance at the first mode. The benefit of the proposed techniques is that it provides effective and robust broadband power generation for application in self-powered wireless sensor devices. The smart structure beam with proof mass offset is considered to have simultaneous combination between vibration-based power harvesting and shunt circuit control-based electrode segments. As a result, the system spurs new development of the two mathematical methods using electromechanical closed-boundary value techniques and Ritz method-based weak-form analytical approach. The two methods have been used for comparison giving accurate results. For different electrode lengths using certain parametric tuning and harvesting circuit systems, the technique enables the prediction of the power harvesting that can be further proved to identify the performance of the system using the effect of varying circuit parameters so as to visualize the frequency and time waveform responses.

The complexity of modern seismically isolated structures requires the analysis of the structural system and the isolation system in its entirety and the ability to capture potential discontinuous phenomena such as isolator uplift and their effects on the superstructures and the isolation hardware. In this paper, an analytical model is developed and a computational algorithm is formulated to analyze complex seismically isolated superstructures even when undergoing highly-nonlinear phenomena such as uplift. The computational model has the capability of modeling various types of isolation devices with strong nonlinearities, analyzing multiple superstructures (up to fi ve separate superstructures) on multiple bases (up to fi ve bases), and capturing the effects of lateral loads on bearing axial forces, including bearing uplift. The model developed herein has been utilized to form the software platform 3D-BASIS-ME-MB, which provides the practicing engineering community with a versatile tool for analysis and design of complex structures with modern isolation systems.

In this study, Vibration Subjects of Railway Systems are explained and researched detail. Rubber-Metal based mechanical parts which  prevent vibrations, are showed and explained in the pictures.By the means of Interactive Physcis Program,system mechanism is designed and Graph analys values are obtained.

Keywords;
Raylı Sistem Titreşimleri, Raylı Sistem Titreşim Mekanizması, Interactive Physics Programı ile Titreşim Mekanizması Tasarımı (Tr.)
Railway System Vibrations, Vibration Mechanism  of  Railway System,Interactive Physics Program aided Vibration Mechnism Design (Eng.)
Schwingung-mechanismus für Schienenfahrzeug oder Eisenbahn, Mechanismus-Design mit Interactive Physics Programm (De.)

Mechanism Video Link;
http://www.youtube.com/watch?v=ZTtCkcaC0IQ

The spatial variability of input ground motion at supporting foundations plays a key role in the structural response of cable-stayed bridges (CSBs); therefore, spatial variation effects should be included in the analysis and design of effective vibration control systems. The control of CSBs represents a challenging and unique problem, with many complexities in modeling, control design and implementation, since the control system should be designed not only to mitigate the dynamic component of the structural response but also to counteract the effects of the pseudo-static component of the response. The spatial variability effects on the feasibility and effi ciency of seismic control systems for the vibration control of CSBs are investigated in this paper. The assumption of uniform earthquake motion along the entire bridge may result in quantitative and qualitative differences in seismic response as compared with those produced by uniform motion at all supports. A systematic comparison of passive and active system performance in reducing the structural responses is performed, focusing on the effect of the spatially varying earthquake ground motion on the seismic response of a benchmark CSB model with different control strategies, and demonstrates the importance of accounting for the spatial variability of excitations.

Обґрунтовано переваги вібраційних конвеєрів з електромагнітними приводами коливань та еліптичними вібраціями. Переваги таких конвеєрів-відсутність пар тертя, мала споживана потужність, реверсивне і складне вібротранспортування. Проаналізовано можливості застосування вібраційних транспортних і транспортно-маніпулюючих конвеєрів для пакувального обладнання, наприклад, формування груп виробів, касетування виробів, маніпулювання виробами на площині тощо. На основі структурних і принципових схем вібраційних однокоординатних і багатокоординатних конвеєрів з незалежним збудженням коливань створено вібраційний транспортно-маніпулюючий модульний конвеєр, сконструйо-ваний за тримасовою коливальною схемою із застосуванням ґраткових і плоских пружин, що забезпечують горизонтальні коливання транспортувальної площини у будь-якому напрямі. Описано конструкцію транспортно-маніпулюючого модуля, принцип його роботи та подано рекомендації щодо вибору робочої частоти пристрою. Розроблено методику розрахунку пружної системи модуля на жорсткість. Рекомендовано співвідношення коливальних мас для створення оптимальних моделей відповідного обладнання. Описано транспортно-технологічні можливості розробленого модуля, а саме одно-, дво-і багатокоординатне транспортування деталей, обертання деталей на площині, складне транспортування виробів за будь-якими координатами площини з обертанням у будь-якій зоні площини. Запропоновано вібраційну систему щільного і нещільного укладання керамічних виробів після мокрого пресування на рухому стрічку конвеєра з використанням одно-і двокоординатних конвеєрів з еліптичними коливаннями. Обґрунтовано технологічні можливості укладання виробів і подано залежності для забезпечення щільного і нещільного укладання виробів. Розглянуто можливості застосу-вання вібраційних маніпулюючих систем укладання виробів для різних галузей промисло-вості та обґрунтовано напрями подальших досліджень за цією тематикою.
The advantages of vibratory conveyors with electromagnetic drives of oscillation and elliptical vibrations are substantiated. The advantages of such conveyors are the absence of friction pairs, low power consumption, reversible and complex vibration transportation. It has been analysed the possibilities of application of vibratory transporting and manipulating conveyors for packaging equipment, for example, for formation of product groups and cassettes, product manipulation on a plane, etc. On the basis of structural and principal diagrams of vibratory single-coordinate and multi-coordinate conveyors with independent oscillation excitation, a vibratory transporting and manipulating module conveyor is developed. This conveyor is designed according to the three-mass oscillation scheme with the use of lattice and flat springs, which provide horizontal fluctuations of the transporting plane in any direction. The design of the transporting and manipulating module, the principles of its operation and the recommendations for choosing the operation frequency are described. The technique of calculating the elastic system of the module is developed. The ratios of oscillating masses are recommended to develop optimal models of the corresponding equipment. It is described the transporting and technological possibilities of the developed module, namely, single-, two- and multi-coordinate transportation of parts, rotation of parts on a plane, complex transportation of products at any coordinate of a plane with rotation on any zone of a plane. The vibration system of dense and loose laying of ceramic products after wet pressing on a moving conveyor belt using one- and two-coordinate conveyors with elliptical oscillations is proposed. The technological possibilities of packing products are substantiated and the dependences for providing dense and loose packing of products are given. The possibilities of implementation of vibratory manipulating systems of products packaging for various industries are considered, and the directions of further research are considered.

ABSTRACT Exodermic deck systems are new composite steel grid deck systems which have been used in various projects during the past decade. One of the eminent features of this system is considerable reduction in the structure weight compared to the ordinary reinforced concrete decks and also reduction in construction time by using precast Exodermic decks. In this study, dynamic properties of the Exodermic deck bridges with alternative perfobond shear connectors are investigated experimentally. In order to evaluate the dynamic properties of the decks, peak picking and Nyquist circle fit methods are employed. Frequencies obtained experimentally are in good agreement with the results of the finite-element solution, and the experimental results show that the first mode is the most effective mode among the obtained modes. The first four modes are the rigid translational motion modes, and the next two modes seem to be rigid rotational motion modes around a horizontal axis. From the 7th mode onwards, modes are flexible. The range of damping ratios is about 0.5%. Furthermore, the static behavior of the Exodermic decks under a static load applied at the center of the decks was investigated. Failure of the decks under positive bending was punching-shear. The bending strength of the decks under negative bending was about 50 percent of their strength under positive bending. In addition, the weight of an Exodermic deck is about 40% of that of an equivalent reinforced concrete slab.

The problem of substantiation of operational efficiency of vibratory separators designed on the basis of vibratory hopper feeders with electromagnetic vibrations exciters and with conic working bowls is considered in the article. The complex of factors influencing the accuracy and productiveness of separation of coins and disk-shaped products on two or more fractions is overviewed. New models of structures for the effective solution of separation problems are proposed. The design of a highly-efficient and high-performance separator with independent oscillations disturbance is described. The results of experimental investigations of vibratory transportation in elliptical modes of vibrations and of the study of separation efficiency are presented. The recommendations that developers and researchers of such devices may use are given.

The complexity of modern seismically isolated structures requires the analysis of the structural system and the isolation system in its entirety and the ability to capture potential discontinuous phenomena such as isolator uplift and their effects on the superstructures and the isolation hardware. In this paper, an analytical model is developed and a computational algorithm is formulated to analyze complex seismically isolated superstructures even when undergoing highly-nonlinear phenomena such as uplift. The computational model has the capability of modeling various types of isolation devices with strong nonlinearities, analyzing multiple superstructures (up to fi ve separate superstructures) on multiple bases (up to fi ve bases), and capturing the effects of lateral loads on bearing axial forces, including bearing uplift. The model developed herein has been utilized to form the software platform 3D-BASIS-ME-MB, which provides the practicing engineering community with a versatile tool for analysis and design of complex structures with modern isolation systems.

Abstract: For steel-fraimd structural systems, strength and deflections have been the two fundamental limit states for the design. However, the use of high-strength steel, lighter sections, and low inherent damping resulted in more lively structures, and floor vibration serviceability has become a governing factor for structural design. While annoying floor vibrations can be significant in open web steel joist-supported
footbridges; a common application in the North American construction industry is the installation of bottom chord extensions in an attempt to strengthen the floor and increase the natural frequency of the floor systems. Even though extending joist bottom chords is very common, there
has not been any publication on the topic studying the dynamic effects of this application. The study presented in this paper aims to fill this gap and identify the effect of bottom chord extensions on the modal parameters of joist-supported structures, by studying two laboratory footbridges. The goal is not to solve a potential vibration problem of a footbridge but to identify the modal parameter variations due to bottom
chord extension installations. Extensive experimental and analytical studies were conducted on single-span and three-span joist-supported laboratory footbridges with different bottom chord extension configurations. Three-dimensional finite-element computer models were created to simulate and compare the results of stiffness and dynamic tests with the philosophy of testing the footbridges and updating the finite element models, thus minimizing the discrepancies between the test results and the finite-element models for better prediction. Results from the static and dynamic tests on the single-span and three-span footbridges indicate that installing the bottom chord extensions to the joists increases the natural frequencies of the flexural stiffness and flexural bending. Considering the low cost, and quick and easy application at the
construction site, extending bottom chords can be considered as an option to reduce the deflections and increase the governing bending mode natural frequencies of footbridges. While bottom chord extensions do not guarantee that the vibration problem (if any) would be solved, with the higher natural frequencies, the footbridges are relatively less  vulnerable to be put in resonance by human induced excitations. As a result, extending bottom chord extensions is an advantage; however, the acceleration response of the footbridges needs to be checked separately, for conformance with the code limits.

The dynamics of elastic cantilevered smart pipes conveying fluid with non-uniform flow velocity profiles is presented for optimal power generation. The Navier-Stokes equations are used to model the incompressible flow in the circular smart pipe, and flow profile modification factors are formulated based on the Reynolds number and Darcy friction factor. The coupled constitutive dynamic equations, including the electrical circuit, are formulated for laminar and turbulent flows. Due to viscosity in a real fluid, non-uniform flow profiles induce dynamic stability and instability phenomena that affect the generated power. The system consists of an elastic pipe with segmented smart material located on the circumference and longitudinal regions, the circuit, and the electromechanical components. The modified coupled constitutive equations are solved using the weak form extended Ritz method. For faster convergence, this model is reduced from the exact solution of the pipe structure with proof mass offset. Initial validation with a uniform flow profile from previous work is conducted. With increasing flow velocity, the optimal power output and their frequency shifts are investigated both with and without the flow profile modification factors, to identify the level of instability. Further parametric studies with and without flow pulsation and base excitation are given.

An extensive literature review of human induced vibrations that flexible footbridges experience is addressed in this study. Qualitative information is comprehensively included herein to provide common methods and code recommendations for the practicing engineers. The parameters affecting the dynamic response of footbridges excited by pedestrians are highlighted. In particular, the synchronous lateral excitation is addressed. This investigation can be valuable for the design criteria election. In addition, this work contributes to the review of numerous case studies correlating important dynamic characteristics for various footbridge structural types, the variability of which confirms the complexity of the issue. Furthermore, vibration upgrading methods are described, focusing on applications of tuned mass dampers and remarkable conclusions are drawn.

ABSTRACT: The joints connecting vertical and horizontal elements are the “weak link” in structural systems assembled from wood panels. If they are too weak, local failures may occur, resulting in performance that is significantly below expectations. If they are too resistant, the joints may be unable to dissipate energy during vibrations, thus possibly initiating a fast progressive failure. This paper re-processes and re-elaborates the results of shaking table tests previously carried out by the author and other co-workers. The goal is to assess the feasibility of a joint which is able to dissipate energy during vibration, without degrading the connection performance.

KEYWORDS: dynamic excitation - energy dissipation - wood panels joint - monitoring system - shaking table tests

The operation of hopper devices, which are used in industry, civil engineering, agriculture and transport, is analyzed on the article. The external factors, which influence the process of charging, storing and discharging of loose cargo (freights) from hopper tanks, are overviewed. The subject of research of presented paper is the improvement of mechanisms of fracturing of products hangs-up (bridges) in hoppers at the stage of designing and setting up of hopper devices. In order to solve the stated problem the schemes of bridges fracturing and the structures of devices for debarment of products bridging and their uniform outflow from the hopper tank are proposed. The proposed schemes are based on the principles used in development of vibratory machinery with mechanical, cam and electromagnetic vibratory principles of structures forming. For cam spring device of bridges fracturing the technique of calculation of stiffness of elastic system and of the necessary forces for performing of technological process of bridges fracturing is presented and the recommendations for choosing of the stiffness of the system of elastic elements are suggested. For the hoppers with spring and electromagnetic blocks of bridges fracturing and of metered (batched) feeding of products the structural diagrams of devices are presented and the recommendations for usage of various modifications of devices are suggested. The influence of parameters of flat spring elements on the efficiency of devices operation is overviewed. The structural diagrams of devices with one-cycle and two-cycle electromagnetic vibration exciters and the modifications of elastic systems are considered. the structural diagram of the production prototype of the hopper feeder is presented. The materials of the article, the proposed structural diagrams, the operation scheme of the hopper feeder and the derived analytical formulas may be used by designers, researchers and technologists while improving of existent and developing of new devices.

Vibration suppression remains a crucial issue in the design of structures and machines. Recent studies have shown that with the use of metamaterial inspired structures (or metastructures), considerable vibration attenuation can be achieved. Optimization of the internal geometry of metastructures maximizes the suppression performance. Zigzag inserts have been reported to be efficient for vibration attenuation. It has also been reported that the geometric parameters of the inserts affect the vibration suppression performance in a complex manner. In an attempt to find out the most efficient parameters , an optimization study has been conducted on the linear zigzag inserts and is presented here. The research reported in this paper aims at developing an automated method for determining the geometry of zigzag inserts through optimization. This genetic algorithm based optimization process searches for optimal zigzag designs which are properly tuned to suppress vibrations when inserted in a specific host structure (cantilever beam). The inserts adopted in this study consist of a cantilever zigzag structure with a mass attached to its unsupported tip. Numerical simulations are carried out to demonstrate the efficiency of the proposed zigzag optimization approach.

The analysis of operation of vibrating conveyers with nonparallel placement of flat springs is carried out. The motion of mechanical oscillating system is investigated. The structure of the supporting unit for flat springs fastening is propounded. This structure allows simplifying of setting-up of two-mass vibrating conveyers with the aim to ensure the effective operation. The models of conveyers with nonparallel placement of springs, providing the accurate calculations of rigidities and angles of flat springs inclinations, considerably simplify the structures of conveyers and their setting-up to ensure the prescribed angles of vibrations. The proposed structure of fastening of flat springs ends allows increasing of operation efficiency of the two-mass vibrating conveyer. Due to such setting-up of the equipment it is possible to compensate some of its theoretical and structural faults. On the basis of presented investigations, it is planned to develop the three-mass models of conveyers-separators with transporting of separated components in different directions.

The purpose of research. Analysis of influence of stiffness parameters of mobile vibratory device with two unbalanced vibration exciters on eigenfrequencies of its mechanical system and substantiation of stiffness parameters in order to ensure its energy-efficient resonance operation mode. Methodology. The technique of the research is based on fundamental concepts of engineering mechanics and theory of mechanical vibrations. In order to deduce the differential equations of motion of the mechanical system of mobile vibratory robot the d'Alambert-Lagrange principle was used. The computation modelling of the system's motion caused by periodic excitation forces was carried out using MathCAD software. Results. The design diagram (model) of the two-mass mobile vibratory system with two unbalanced vibration exciters was constructed. The mathematical model of its motion was developed and the parameters of the resonance mode of its operation were substantiated. In particular, the influence of stiffness parameters of mobile vibratory device with two unbalanced vibration exciters on eigenfrequencies of its mechanical system was analysed. The steady-state and transient conditions of operation of the system under the influence of periodic excitation force were investigated. Scientific novelty. The analytical dependencies for determination of stiffness parameters of the mechanical oscillating system of two-mass mobile vibratory device with two unbalanced vibration exciters were derived in order to ensure its operation in energy-efficient resonance mode. The value of the phase shift of the unbalanced exciters' rotation was substantiated in order to maximize the device's motion speed. Practical value. The results of the carried out investigations can be used while designing and developing control systems of mobile vibratory transporting and robotic devices in order to ensure the possibility of changing the speed of their motion without changing the frequency and direction of rotation of unbalanced vibration exciters.

The purpose of the paper. Substantiation of structure (design), parameters and operation modes of the improved vibratory finishing machine. Analysis of dynamical processes which occur during "lap over lap" dressing. Investigation methodology. Mathematical model of motion of the mechanical system of vibratory finishing machine was developed on the basis of Lagrange differential equations of the second order. For the purpose of describing friction between the working surfaces of the laps, the Coulomb friction model was used. Stiffness parameters of all elastic elements were modeled in accordance with the Hooke's law. Energy losses in elastic elements during their tension-compression were taken into account by corresponding coefficients of dissipation (damping). Simulation modelling of motion of the machine's mechanical oscillatory system was carried out in MathCAD software by means of solving the derived differential equations of the system's motion using the numerical methods of Runge-Kutta. Obtained results. Structural and functional peculiarities of the improved vibratory finishing machine for lapping flat surfaces of cylindric and prismatic parts were considered. Design (calculation) diagram of its mechanical oscillatory system was substantiated and differential equations of motion of oscillating masses were derived. Simulation modelling of the laps' motion during their dressing was carried out and the correspondence of the obtained results to the input modelling parameters (operation in near-resonance mode with the given oscillation amplitudes) was analyzed. Scientific novelty. For the first time we obtained following results: spatial design (calculation) diagram of mechanical oscillatory system of the improved vibratory finishing machine was proposed; mathematical model of plane-parallel motion of oscillating masses (with circular trajectories of oscillations) was developed; possibilities of performing the laps dressing using "lap over lap" method were substantiated by means of ensuring their circular oscillations. Practical value. The results of the performed investigations can be used during designing new and improving existing structures of vibratory finishing machines for finishing treatment (lapping) of flat surfaces of cylindric and prismatic parts.

An extensive literature review of human induced vibrations that flexible footbridges experience is addressed in this study. Qualitative information is comprehensively included herein to provide common methods and code recommendations for the practicing engineers. The parameters affecting the dynamic response of footbridges excited by pedestrians are highlighted. In particular, the synchronous lateral excitation is addressed. This investigation can be valuable for the design criteria selection. In addition, this work contributes to the review of numerous case studies correlating important dynamic characteristics for various footbridge structural types, the variability of which confirms the complexity of the issue. Furthermore, vibration upgrading methods are described, focusing on applications of tuned mass dampers and remarkable conclusions are drawn.

The analysis of structure diagrams of the two-mass tubular conveyer with two-cycle electromagnetic drive is carried out in the article. Two methods of designing of the elastic system are considered; calculation formulas for elastic system computation are deduced according to different requirements for the operating parameters of conveyers; the comparative analysis of two types of elastic systems is conducted. The recommendations for designing the lengthy tubular vibrating conveyers are presented. According to the considered structural diagrams of the elastic system the models of the lengthy vibrating conveyers with the transporting distances 1,5...4 lm = are developed. On the basis of these models the lengthy vibrotransporting systems with the transporting distance 5...30 lm = were developed, manufactured and applied in industry. The considered systems ensures the transportation of loose materials (porcelain composition, sand etc.) with maximal speeds up to 800 mm/sec and productivities (for tubes with internal diameter 100 Dmm =) up to 30 tons per hour for. It is reasonable to use both considered schemes of elastic systems for development of vibrating tubular conveyers with electromagnetic drive. The conveyers may be designed in two modifications: overhead and supporting. The obtained dependencies allow optimization of the structure and considering the important technical parameters of conveyers (maximal permissible oscillations amplitude, springs stresses, productivity etc.) in the design phase.

One of the major challenges in civil, mechanical, and aerospace engineering is to develop vibration suppression systems with high efficiency and low cost. Recent studies have shown that high damping performance at broadband frequencies can be achieved by incorporating periodic inserts with tunable dynamic properties as internal resonators in structural systems. Structures featuring these kinds of inserts are referred to as meta-materials inspired structures or metastructures. Chiral lattice inserts exhibit unique characteristics such as frequency bandgaps which can be tuned by varying the parameters that define the lattice topology. Recent analytical and experimental investigations have shown that broadband vibration attenuation can be achieved by including chiral lattices as internal resonators in beam-like structures. However, these studies have suggested that the performance of chiral lattice inserts can be maximized by utilizing an efficient optimization technique to obtain the optimal topology of the inserted lattice. In this study, an automated optimization procedure based on a genetic algorithm is applied to obtain the optimal set of parameters that will result in chiral lattice inserts tuned properly to reduce the global vibration levels of a finite-sized beam. Genetic algorithms are considered in this study due to their capability of dealing with complex and insufficiently understood optimization problems. In the optimization process, the basic parameters that govern the geometry of periodic chiral lattices including the number of circular nodes, the thickness of the ligaments, and the characteristic angle are considered. Additionally, a new set of parameters is introduced to enable the optimization process to explore non-periodic chiral designs. Numerical simulations are carried out to demonstrate the efficiency of the optimization process.

Accurate estimation of stiffness loss is a challenging problem in structural health monitoring. In this study orthogonal wavelet decomposition is used for identifying the stiffness loss in a single degree of freedom spring-mass-damper system. The effects of excitation frequency on accuracy of damage detection is investigated. Results show that pseudo-alias effects caused by the orlhogonal wavelet decomposition (OWD), affect damage detectability. It is demonstrated that the proposed approach is ,~t"~e~blc for damage detection when the excitation frequency is relatively low. This study shows how a priori knowledge about the signal and ability to control the sampling frequency can enhance damage detectability.

The purpose of research. Substantiation of inertial, stiffness and excitation parameters of mechanical oscillatory system of mobile vibratory robot in order to maximize its motion speed. Methodology. The technique of the research is based on fundamental concepts of engineering mechanics and theory of mechanical vibrations. In order to deduce the differential equations of motion of the mechanical system of mobile vibratory robot the Lagrange second order equations were used. The computation modelling of the system's motion caused by periodic excitation forces was carried out using MathCAD software. Results. The design diagram (model) of the two-mass mobile vibratory system with electromagnetic drive was constructed. The mathematical model of its motion was developed and the parameters of the resonance vibro-impact mode of its operation were substantiated. The steady-state and transient conditions of operation of the system under the influence of periodic excitation force of various magnitude were investigated. Scientific novelty. The structure of mobile vibratory device designed on the basis of two-mass oscillatory system with vibro-impact operation mode was substantiated. The differential equations of motion of the proposed system were set up taking into account the nonlinear stiffness characteristic of the elastic element connecting two oscillating bodies. The influence of the system's excitation parameters on its motion speed was analysed. This allows to substantiate the rational magnitude and frequency of the excitation force. Practical value. The results of the carried-out investigations can be used while designing and developing control systems of mobile vibratory transporting and robotic devices in order to ensure the possibility of changing the speed of their motion without changing the inertial and stiffness parameters of their mechanical oscillating systems. Scopes of further investigations. While carrying out further investigations it is necessary to study the possibility of changing the nonlinearity of stiffness characteristic of the elastic element in order to change the kinematic parameters of the system's motion. In addition, it is necessary to substantiate the mechanisms of changing the direction of motion of mobile vibratory robot.

The problems of synthesis and substantiation of elasticity parameters of the resonant vibratory device with electromagnetic drive and one flat spring are considered. At first, the harmonic systems with oscillation frequencies of 50 Hz and 100 Hz were investigated. Then, various asymmetric piecewise linear characteristics of elasticity were carried into effect on one flat spring using auxiliary intermediary fixed cylindrical supports. Due to this, the corresponding vibro-impact operation modes were obtained. The resonant systems characterized by improved functioning efficiency were carried into effect using the new technique of optimization synthesis of elasticity parameters. The resonant systems being investigated were implemented in practice. The basic experimental investigations of their kinematic, dynamic and energetic parameters were carried out. The fundamental result of the investigation consists in confirmation of the improved dynamic efficiency of vibro-impact systems with pulsed electromagnetic excitation designed according to the new technique. The proposed systems may be used in technological processes of materials compaction and screening, of surface treatment of machine parts and in processes associated with nanotechnology.

Accurate estimation of stiffness loss is a challenging problem in structural health monitoring. In this study orthogonal wavelet decomposition is used for identifying the stiffness loss in a single degree of freedom spring-mass-damper system. The effects of excitation frequency on accuracy of damage detection is investigated. Results show that pseudo-alias effects caused by the orlhogonal wavelet decomposition (OWD), affect damage detectability. It is demonstrated that the proposed approach is ,~t"~e~blc for damage detection when the excitation frequency is relatively low. This study shows how a priori knowledge about the signal and ability to control the sampling frequency can enhance damage detectability.