Adam Martowicz

Nonlinear vibroacoustic wave modulations for structural damage detection: an overview

Abstract. We present an overview of research developments related to the nonlinear vibroacoustic modulation technique used for structural damage detection. The method of interest is based on nonlinear interactions of a low-frequency pumping wave and a high-frequency probing wave. These two waves are introduced to monitored structures simultaneously. Then the presence of damage is exhibited by additional frequency components that result from nonlinear damage-wave interactions. A vast amount of research has been performed in this area over the last two decades. We aim to present the state-of-the-art of these developments. The major focus is on monitoring approaches, modeling aspects, actuation/sensing, signal processing, and application examples.

Application of electromechanical impedance-based SHM for damage detection in bolted pipeline connection

The work discusses the effectiveness of the electromechanical impedance-based Structural Health Monitoring system for damage detection in a laboratory test stand – a bolted pipeline section. The impedance-based system developed by the authors and equipped with 12 piezoelectric transducers was used to acquire the data. Different damage scenarios related to loosened bolts and measurement configurations are analysed. Both point and transfer frequency response functions are applied to deterministic and stochastic damage metrics, which are used to assess the condition of the monitored structure. The thresholds levels are proposed for different measurement configurations. Moreover, the authors discuss the perspective to determine the size and localisation of a damage. As confirmed in the work, the stochastic damage metric, preferably applied with a transfer frequency response, is found as of the most practical significance for the tested structure. The carried out analyses consider an outlier removal technique, which becomes necessary to prevent from errors due to temporary variation of the acquired characteristics after initialisation of the measurements.

Uncertainty analysis for dynamic properties of MEMS resonator supported by fuzzy arithmetics

In the paper the application of uncertainty analysis performed for microelectromechanical resonator is presented. Main objective of undertaken analysis is to assess the propagation of considered uncertainties in the variation of chosen dynamic characteristics of Finite Element model of microresonator. Many different model parameters have been assumed to be uncertain: geometry and material properties. Apart from total uncertainty propagation, sensitivity analysis has been carried out to study separate influences of all input uncertain characteristics. Uncertainty analysis has been performed by means of fuzzy arithmetics in which alpha-cut strategy has been applied to assemble output fuzzy number. Monte Carlo Simulation and Genetic Algorithms have been employed to calculate intervals connected with each alpha-cut of searched fuzzy number. Elaborated model of microresonator has taken into account in a simplified way the presence of surrounding air and constant electrostatic field.

Electromechanical Impedance Based SHM System for Aviation Applications

This paper concerns an approach based on the electromechanical impedance for damage detection and monitoring of aircraft components. In the introductory part of the paper the theory of proposed method and the characteristics of elaborated structural health monitoring system are briefly described. Afterwards, applications of described system applied to damage detection in different aircraft components are presented. First, the process of monitoring of bolted joints localized in the fuselage is described and effectiveness of this process is discussed. In the application four PZT patches were used to track a torque decrease in three joints. The latter application deals with monitoring of riveted engine housing made of aluminium. Introduced notch was monitored with two MFC transducers. In both mentioned cases the frequency characteristics of measured impedance were compared using different deterministic and statistical damage indexes.

Study of the Effect of Process Induced Uncertainties on the Performance of a Micro-Comb Resonator

This paper presents a modeling technique based on the integration in the classic deterministic simulation methods of probabilistic computational techniques such as uncertainty analysis and sensitivity analysis. As study case, it is presented a micro-comb resonator that is actuated electrostatically to vibrate in the plane parallel to the substrate. A deterministic Finite Element coupled electromechanical analysis is performed to evaluate the mode shapes and the corresponding eigenfrequencies of the mobile mass and afterwards a Monte Carlo simulation is used to determine the dispersion of the eigenfrequency of the mode shape of interest in function of the variations of the input parameters. The scatter of the results is analyzed and then it is presented a sensitivity analysis for establishing which of the input parameters have more influence on the variability of the microresonators performance.

Non-local modeling and simulation of wave propagation and crack growth

The paper presents the results of numerical analyses carried out for 2D models of aluminum plates undergoing crack propagation. Different types of numerical analyses were performed to show the area of applicability of a non-local discrete formulation of mechanical continua for NDE and QNDE. The authors’ interests dealt with: Lamb wave propagation, higher harmonics generation, the phenomenon of clapping, and wave generation and its propagation for growing crack. In the first case a 2D model allowed to find the displacements for the vertical cross-section along the direction of wave propagation and therefore assess its disturbance when introducing a notch. In-plane components of the displacements were considered for the latter 3 cases, in turn. The above cases and elaborated non-local numerical models were discussed in terms of detection of propagating crack. Apart from theoretical aspects of the presented work, the obtained results seem to be of great importance for improvement of experiments in terms of sensor distribution and required accuracy.The paper presents the results of numerical analyses carried out for 2D models of aluminum plates undergoing crack propagation. Different types of numerical analyses were performed to show the area of applicability of a non-local discrete formulation of mechanical continua for NDE and QNDE. The authors’ interests dealt with: Lamb wave propagation, higher harmonics generation, the phenomenon of clapping, and wave generation and its propagation for growing crack. In the first case a 2D model allowed to find the displacements for the vertical cross-section along the direction of wave propagation and therefore assess its disturbance when introducing a notch. In-plane components of the displacements were considered for the latter 3 cases, in turn. The above cases and elaborated non-local numerical models were discussed in terms of detection of propagating crack. Apart from theoretical aspects of the presented work, the obtained results seem to be of great importance for improvement of experiments in terms of s...

Damage Detection in Riveted Aircraft Elements Based on the Electromechanical Impedance Measurements

This work is devoted to the use of the electromechanical impedance method for the damage detection in a riveted aircraft element. In the first part of the paper a theoretical background of the impedance-based damage detection technique is made. Next, the description of the utilised experimental set-up is described. Then, an application of the method used to detect damage in a wing sheathing of a turboprop training aircraft is presented. A damage scheme incorporating multiple notches through the selected rivets is considered. Finally, the suitability of the described method to distinguish close and far field damages is discussed.

A new 3-DOF parallel manipulator

The paper presents a novel, versatile 3-RRP_RR (revolute-revolute-prismatic-revolute-revolute joints), fully-parallel manipulator with three translational degrees of freedom for pick-and-place and machining applications, characterizing in comparatively high payload capacity, large workspace and high attainable accelerations. The construction of the manipulator is shown, its kinematics and dynamics is analysed and modelled. A trajectory generator and a controller are proposed, simulated and experimentally investigated. Finally, the conclusions and future works are presented.

Peridynamics as an analysis tool for wave propagation in graphene nanoribbons

The work is devoted to the study on elastic wave propagation in graphene nanoribbons, performed with peridynamics. Graphene nanoribbons have recently gained dramatic increase of interest in the fields of nanoelectronics and nanoelectromechanical systems. They can play a key role as either modern metallic or semiconductor materials, depending on the edge structure, with zigzag or armchair layout, respectively. Moreover, graphene opens new perspectives for the millimeter wave-based measurements systems. The authors present a peridynamic model used as alternative approach to analyze the dynamic behavior of a graphene nanoribbon. The model is considered as a periodic structure, i.e. an assembly of fundamental structural elements, with the first Brillouin zone under study, which undergoes propagation of elastic wave. The commonly applied auxiliary atomistic-continuum model for a C-C bond is used to set equivalent elastic properties, which are applied to find reference dispersion relation via FE model to study the behavior of the peridynamic model. The paper discusses its capability of recovering the physical nature of the reactions at the atomic scale present in a graphene applying dispersion characteristics. The peridynamic model of the graphene nanoribbon results from upscaling process carried out for a small-scale atomic model, making use of reference dispersion curve. The material properties are homogenized over studied domain indirectly by tuning the phase velocity for longitudinal in-plane elastic waves. As shown, nonlocal nature of peridynamics allows to preserve the lengthscale effect, local small-scale inhomogeneity and wave dispersion. Hence, the effect of spatial discretization at nano scale, arising from the distribution of atoms of carbon in the structure of graphene, may be represented with a nonlocal peridynamic model effectively.

Uncertainty and sensitivity analysis of electro-mechanical impedance based SHM system

The paper deals with the application of uncertainty and sensitivity analysis performed for FE simulations for electro-mechanical impedance based SHM system. The measurement of electro-mechanical impedance allows to follow changes of mechanical properties of monitored construction. Therefore it can be effectively applied to conclude about presence of damage. Coupled FE simulations have been carried out for simultaneous consideration of both structural dynamics and piezoelectric properties of a simple beam with bonded transducer. Several indexes have been used to assess the damage growth. In the paper the results obtained with both deterministic and stochastic simulations are shown and discussed. First, the relationship between size of introduced damage and its indexes has been studied. Second, ranges of variation of selected model properties have been assumed to find relationships between them and damage indexes. The most influential parameters have been found. Finally, the overall propagation of considered uncertainty has been assessed and related histograms plotted to discuss effectiveness and robustness of tested damage indexes based on the measurement of electro-mechanical impedance.