Emiliano Rustighi

Università degli Studi di Trento | UNITN · Department of Industrial Engineering

Vibration neutralisers are widely used to suppress vibration of a host structure subject to external excitation at a specific frequency. When attached to a structure, they create a notch filter in the frequency response, reducing the vibration levels considerably. An inherent limitation is related to the narrow frequency range in which they are eff...

Acoustic techniques remain the bedrock of pipeline leak detection, particularly for the water industry. The correlation technique, in which leak noise measurements are made at accessible locations on the pipe, either side of the leak, is used world-wide. Unfortunately, especially in the case of plastic pipes, access points are often not spaced clos...

The acoustic camera is an established and highly effective device for localising acoustic sources by the use of a number of simultaneously acquired signals from an array of pressure sensors (microphones). The acoustic camera essentially provides for a highly directional sensor in which the signals arriving from the noise source in the steered main...

The acoustic camera is an established and highly effective device for localising acoustic sources by the use of a number of simultaneously acquired signals from an array of pressure sensors (microphones). The acoustic camera essentially provides for a highly directional sensor in which the signals arriving from the noise source in the steered main...

Acoustic techniques remain the bedrock of pipeline leak detection, particularly for the water industry. The correlation technique, in which leak noise measurements are made at accessible locations on the pipe, either side of the leak, is used world-wide. Unfortunately, especially in the case of plastic pipes, access points are often not spaced clos...

The need to reduce non-exhaust particulate matter emissions is of paramount importance as they pose repercussions on human lives and the environment. In this study, a novel way to limit emissions is proposed based on the minimization of the vibration of the mating bodies. Two model friction material formulations were tested in the form of pins and...

The fundamental beam structure is often regarded as a wave or energy carrier in a wide range of research topics for structural engineering. Nevertheless, in the related literature the beam is positioned either horizontally or vertically, which may limit its application flexibility. Very few studies have investigated the energy conversion and vibrat...

This article proposes a simple physical-based model to describe and predict the performance of axially compressed magnetorheological elastomer cylinders used as vibration and shock absorbers. The model describes the magnetorheological elastomer macroscopic stiffness changes because of an externally applied magnetic field from a microscopic composit...

Various complex shapes of dielectric electro-active polymer (DEAP) actuator have been promoted for several types of applications. In this study, the actuation and mechanical dynamics characteristics of a new core free flat DEAP soft actuator were investigated. This actuator was developed by Danfoss PolyPower. DC voltage of up to 2000 V was supplied...

Off-road motorcycles transit over significantly irregular terrains facilitated by their suspension system. The optimisation of their suspension is an open topic. On one hand, on-road motorcycles need to be extended to consider off-road peculiarities such as larger amplitude of motion and a standing rider, to provide optimisation predictions. On the...

An appropriate model of leak noise at source is necessary in analytical and numerical approaches to investigate the characteristics of leak noise measured remotely from the leak in buried water pipes. It is extremely difficult to measure leak noise at source in practice, so an inverse method is needed to predict this from measurements made either s...

Assessment of the location and extension of cracking in road surfaces is important for determining the potential level of deterioration in the road and in the infrastructure buried beneath it. Damage in a pavement structure is usually initiated in the asphalt layers, making the Rayleigh wave ideally suited to the detection of shallow surface defect...

Leakage from pipes is a major issue in both the oil and gas sectors, not only in environmental and economic terms, because of wasting important natural resources, but importantly from a safety perspective. Optical fibre technology offers the possibility of continuous acoustic monitoring of pipelines and remote detection of leaks. In this paper we p...

Ice accretions on aircraft lifting surfaces must be removed in flight to avoid catastrophic accidents. Conventionally, this is done effectively but inefficiently by bleeding hot air from the engines prompting a number of low energy approaches to be explored that use high amplitude shock or vibration. One recently proposed method, which has so far b...

p>The assessment of the location and the extension of cracks in roads is important for determining the potential level of deterioration in the road overall and in the infrastructure buried beneath it. Damage in a pavement structure is usually initiated in the tarmac layers, making Rayleigh waves ideally suited for the detection of shallow surface d...

The estimation of tyre forces in off-road motorcycle is required to measure objectively its performance. It requires the interaction between motorcycle and the rider in standing position. The existing rider model for off-road motorcycles is computationally expensive and it has not been validated. In this article we present a model for a standing ri...

This numerical study focuses on the assignment of poles to a planetary gear train to avoid resonance, which can cause the failure of the system. The control strategy is output feedback, which involves feeding back the displacement and velocity to achieve active stiffness and damping respectively. The reverse process was considered. This occurs when...

To improve the performance of off-road motorcycles, tyre contact forces need to be estimated. Differently to on-road motorcycle contact force estimators where the rider can be considered attached to the chassis, an off-road motorcycles estimator needs to model the rider dynamics, since driving in standing position provides significant isolation fro...

This paper presents a nonlinear parametrically excited cantilever beam with electromagnets. A parametrically excited two-degree-of-freedom (2-DOF) system with linear time-varying stiffness, nonlinear cubic stiffness, nonlinear cubic parametric stiffness and nonlinear damping is considered. In previous studies the stability and bifurcation of the no...

Tracing of buried plastic pipes by the means of acoustic methods has become a subject undergoing intense study, thanks to the encouraging results in comparison to other commercial techniques. The current acoustic technique for tracing underground plastic pipes involves the excitation of the pipe wall or the contained fluid at a fixed location. As w...

This paper presents a nonlinear parametrically excited cantilever beam with electromagnets. A parametrically excited two-degree-of-freedom (2-DOF) system with linear time-varying stiffness, nonlinear cubic stiffness, nonlinear cubic parametric stiffness and nonlinear damping is considered. In previous studies the stability and bifurcation of the no...

This paper presents a nonlinear parametrically excited cantilever beam with electromagnets. A parametrically excited two-degree-of-freedom (2-DOF) system with linear time-varying stiffness, nonlinear cubic stiffness, nonlinear cubic parametric stiffness and nonlinear damping is considered. In previous studies the stability and bifurcation of the no...

In this work, the nonlinear behaviour of a parametrically excited system with electromagnetic excitation is accurately modelled, predicted and experimentally investigated. The equations of motion include both the electromechanical coupling factor and the electromechanical damping. Unlike previous studies where only linear time-varying stiffness due...

Conventional loudspeakers are often heavy, require substantial design spaces and are hard to integrate into lightweight structures (e.g., panels). To overcome these drawbacks, this paper presents a novel extremely flat loudspeaker which uses dielectric elastomer actuators with natural rubber for the elastomeric layers and metal electrodes as transd...

Nonlinear Parametrically Excited (NPE) systems govern the dynamics of many engineering applications, from cable-stayed bridges where vibrations need to be suppressed, to energy harvesters, transducers and acoustic amplifiers where vibrations need to be amplified. This work investigates the effect of different system parameters on the dynamics of a...

Tuned Mass Dampers (TMDs) are typically introduced and calibrated as natural passive control devices for the vibration mitigation of the steady-state response of primary structures subjected to persistent excitations. Otherwise, this work investigates the optimum tuning of TMDs towards minimising the transient structural response. Specifically, a s...

Rapid development of urban infrastructure in past decades together with a relatively recent growth of awareness of its impact on the natural environment result in an increased interest in non-destructive ground interrogation methods. Tree root damage is a very well known issue in civil engineering and can emerge as road surface fracture, building f...

Mapping the Underworld (MTU), a major initiative in the UK, is focused on addressing social, 1 environmental and economic consequences raised from the inability to locate buried underground utilities (such as pipes and cables) by developing multi-sensor mobile device. The aim of MTU device is to locate different types of buried assets in real time...

Efficient and accurate predictions of wave propagation are a vital component of wave-based non-destructive interrogation techniques. Although a variety of models are available in the literature, most of them are suited to a particular wave type or a specific frequency regime. In this paper we present a multi-wave model for wave propagation in axisy...

Off-road motorcycle suspensions are subjected to severe solicitations like large jumps and bumps. Its optimisation requires assessing comfort and handling for which several indices can be found in the literature. However these indices were developed for other vehicles and it is not clear how they behave assessing large obstacles. To investigate this...

Axisymmetric waves have characteristics, which are of practical interest when assessing the condition of a buried plastic water pipe. At low frequencies, well below the ring frequency, these waves are dominant. They are well couple to the fluid, pipe wall and surrounding medium and carry a high amount of energy when compared to other waves. Due to...

Whilst the dynamics of tapered structures have been extensively studied numerically and analytically, very few experimental results have been presented to date. The main aim of this paper is to derive and demonstrate an experimental method enabling both axial and flexural wavenumbers in exponentially tapered bars to be estimated. Our particular int...

Finding the location of underground utilities, essentially water pipes, can be difficult and dis-ruptive, due to the lack of efficient techniques that can be used to map these buried network services. Vibro-acoustic methods have been well developed for the purposes of locating underground plastic water pipes. However little literature exists so as...

Unwanted accretions on structures, such as aircraft and wind turbine icing or deposits in pipes, are a common problem, which can pose a serious safety threat if not treated effectively and punctually. In this article we investigate the capability of piezo-excited structural waves to delaminate accreted material. The core of the concept is to utilis...

We address the problem of accurately locating buried utility segments by fusing data from multiple sensors using a novel marching-cross-section (MCS) algorithm. Five types of sensors are used in this work: Ground Penetrating Radar (GPR), Passive Magnetic Fields (PMF), Magnetic Gradiometer (MG), Low Frequency Electromagnetic Fields (LFEM), and Vibro...

Vibro-acoustic techniques have been developed with the aim of determining the location of buried pipes. However, the characteristics of the recorded conical wave radiation from the pipe wall to the surface, at very low frequencies, have not been investigated in depth. By applying any type of excitation, at low frequency, to a typical water pipe, on...

This paper is concerned with an intelligent phonotic crystals (IPC) consisting of an Euler-Bernoulli beam attached with 2DOF locally resonant (LR) structures. The novel design of the dielectric electroactive polymer (DEAP) rings acting as the springs of oscillators is presented that could be employed to control the transmission of flexural waves on...

Waves that propagate at low frequencies in buried pipes are of considerable interest in a variety of practical scenarios, for example leak detection, remote pipe detection, and pipeline condition assessment and monitoring. Particularly useful are the n = 0, or axisymmetric, modes in which there is no displacement (or pressure) variation over the pi...

In this paper we analyse longitudinal wave propagation in exponentially tapered rods from both a theoretical and an experimental perspective. The tapering introduces significant changes to the behaviour of the rod. The longitudinal wave does not propagate from zero frequency, its cut-off frequency depending on the coefficient in the exponent. The a...

"Mapping the Underworld" is a large multi-disciplinary, multi-university research programme taking place in the UK, which aims to revolutionize the way we undertake streetworks. Within this programme, a number of vibration-based techniques for remotely detecting and locating buried pipes have been developed. Relying either on the direct excitation...

This paper proposes an approximate analytic method of obtaining the mechanical impedance of air spring. The sound pressure distribution in cylindrical air spring is calculated based on the linear air wave theory. The influences of different boundary conditions on the acoustic pressure field distribution in cylindrical air spring are analysed. A 1-o...

Assessment of the location and of the extension of cracking in road surfaces is important for determining the potential level of deterioration in the road overall and the infrastructure buried beneath it. Damage in a pavement structure is usually initiated in the tarmac layers, making the Rayleigh wave ideally suited for the detection of shallow su...

A hybrid active-passive vibration isolator made up of electromagnetic actuator and air spring in parallel can be used to effectively isolate the broadband and line spectrum vibration of mechanical equipment simultaneously. However, due to its reliability and safety problems caused by the impact, its application in ships is limited. In this paper, a...

A Nonlinear Parametrically Excited (NPE) system subjected to a harmonic base excitation is presented. Parametric amplification, which is the process of amplifying the system's response with a parametric excitation, has been observed in mechanical and electrical systems. This paper includes an introduction to the equation of motion of interest, a br...

Recent years have seen an increasing interest in the dielectric electroactive polymers (DEAPs) and their potential in actuator applications due to the large strain capabilities. This paper starts with an overview of some configurations of the DEAP actuators and follows with an in-depth literature and technical review of recent advances in the field...

The concept of hybrid active-passive constrained layer damping treatments, which con-sists of viscoelastic materials, piezoelectric materials and elastic constraining materials, was proposed in the 1990s in order to ameliorate problems of instability in traditional ac-tive control systems in the higher frequency range. In this paper, the performanc...

In this paper we present a wave-based technique for modelling waveguides equipped with piezoelectric actuators in which there is no need for common simplifications regarding their dynamic behaviour, the interaction with the waveguide or the bonding conditions. The proposed approach is based on the semi-analytical finite element (SAFE) method. We de...

Waves that propagate at low frequencies in buried pipes are of considerable interest in a variety of practical scenarios, for example leak detection, remote pipe detection, and pipeline condition assessment and monitoring. Whilst there has been considerable research and commercial attention on the accurate location of pipe leakage for many years, t...

The dispersion behaviour of ground roll has been exploited in recent decades for the imaging and acoustic characterization of the shallow subsurface, often using the Multichannel Analysis of Surface Waves (MASW) method. The effectiveness of the method in providing an accurate shear wave profile of a soil deposit and the identification of seismic ev...

Vibration is typically encountered by rotating equipment during its start-up, running operation and shutdown. The severity of the oscillation, which depends on the critical speed and natural frequencies of the system, could cause serious malfunction of the device and affect its operating performance. A simplified lumped parameter model of a rotor s...

The present paper deals with the optimization of a hybrid tuned mass damper (TMD) in reducing the transient structural response due to impulse loading. In particular, a unit impulse excitation has been assumed, acting as base displacement, which is a situation that may occur in different real applications. The proposed hybrid TMD is composed of a p...

Unwanted accretions on structures are a common machinery maintenance problem, which can pose a serious safety threat if not treated effectively and punctually. In this paper we investigate the capability of piezo-excited structural waves for invoking delamination of accreted material from waveguides. We apply a wave-based technique for modelling pi...

Vibration energy harvesting is the transformation of vibration energy to electrical energy. The motivation of this work is to use vibration energy harvesting to power wireless sensors that could be used in inaccessible or hostile environments to transmit information for condition health monitoring. Although considerable work has been done in the ar...

Piezoelectric elements are a key component of modern non-destructive testing (NDT) and structural health monitoring (SHM) systems and play a significant role in many other areas involving dynamic interaction with the structure such as energy harvesting, active control, power ultrasonics or removal of surface accretions using structural waves. In th...

This paper concerns the improvement of High-Static-Low-Dynamic-Stiffness (HSLDS) isolation systems with active damping control. Firstly, a single-degree-of-freedom (SDOF) model is adopted in which a HSLDS isolation system is modelled by Duffing's equation. Harmonic base displacement is considered and an approximate solution to the equation of motio...

Vibrations in mechanical structures are usually undesired and dangerous; hence many technologies have been developed in the past to dissipate their mechanical energy. However, it is advisable to harvest such energy, rather than let it dissipate. The harvested vibration energy may be readily used, for example, to independently power sensors due t...

The tuned vibration absorber is a well-established vibration control device, which can be used to suppress a troublesome resonance or to attenuate the vibration of a structure at a particular forcing frequency. Two of the drawbacks of such a device, however, are that it can detune during operation because of changes in forcing frequency, or that th...

Vibrations in mechanical structures are usually undesired and dangerous; hence many technologies have been developed in the past to dissipate their mechanical energy. However, it is advisable to harvest such energy, rather than let it dissipate. The harvested vibration energy may be readily used, for example, to independently power sensors due to t...

The tuned vibration absorber is a well-established vibration control device, which can be used to suppress a troublesome resonance or to attenuate the vibration of a structure at a particular forcing frequency. Two of the drawbacks of such a device, however, are that it can detune during operation because of changes in forcing frequency, or that th...

In this paper, the problem of energy harvesting with a parametric harvester is presented. A single degree-of freedom (SDOF) mechanical oscillator with time-varying stiffness subject to a harmonic base excitation is considered as a parametric harvester. A periodic time-varying stiffness is introduced to the harvester in order to generate parametric...

The noise emitted from information technology (IT) machines is one of the main annoying sound sources in office environments. Although recent research has aimed at reducing the noise emitted by personal computers (PCs) no major effort has been invested with the study of the characteristic and reduction of the noise emitted by PC keyboards. This pap...

A major UK initiative entitled Mapping the Underworld (MTU) is seeking to address the serious social, environmental and economic consequences arising from an inability to locate - accurately and comprehensively - buried utility service infrastructure without resorting to extensive excavations. MTU aims to develop and prove the efficacy of a multi-s...

Tuned Mass Damper (TMD) devices have been widely studied and optimised in the framework of persistent dynamic loadings, such as harmonic and white noise excitations, in order to reduce as much as possible the steady-state response of an assigned primary structure. In this sense, the present paper arises as a complementary study on the topic, since...