Documents published in Scipedia

• Hybrid structure health monitoring technique for enhancing modal parameter identification accuracy

  E. MUDAHEMUKA, K. Yamamoto

  WCCM2024.

  
  

  Abstract

  SHM relies on the possibility of estimating structural modal parameters, such as mode shapes, natural frequencies, and damping, from the structure’s measured data. Nevertheless, modal parameter estimation still faces accuracy problems. The identification of bridge and/or vehicle system parameters and vibration characteristics have been studied both numerically and experimentally. The knowledge of bridge vibration characteristics and vehicle system parameters is crucial to the maintenance of bridges. The issue is that the techniques used to identify bridge and vehicle system parameters usually work very well with numerical simulation but present accuracy issues with experimental data due to environmental noise. Traditionally, measured data were obtained by instrumenting bridges with connected sensor systems, which had issues such as high cost, maintenance problems, safety concerns, and traffic disruption. More recently, indirect SHM (iSHM) methods, such as drive-by using passing instrumented vehicles, have been researched[1,2]. However, these methods still struggle with the accuracy of modal parameter identification, particularly for higher vibration modes sensitive to localized bridge damage, limiting the widespread adoption of iSHM methodologies[1,3]. A combination of indirect and direct monitoring methods is proposed to address these limitations. This approach aims to improve modal parameter identification, including higher vibration modes, for localized damage detection and structural assessment. The proposed method uses GPS-time synchronized sensors for simultaneous measurement of vehicle and bridge vibration data and is verified through numerical simulation assuming multiple runs over the same bridge. The study highlights the potential of this hybrid SHM technique to significantly improve the accuracy of indirect structural health monitoring, providing more reliable and precise modal parameter estimates, especially for higher vibration modes, allowing for the identification of localized bridge damage.

  Abstract
  SHM relies on the possibility of estimating structural modal parameters, such as mode shapes, natural frequencies, and damping, from the structure’s measured data. Nevertheless, [...]

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• An explicit time-marching procedure for elastodynamic analyses based on adaptive time-integration parameters and time-step values

  L. Ruffo Pinto, D. Soares Jr., I. de Souza Sales, W. João Mansur

  WCCM2024.

  
  

  Abstract

  This study discusses an explicit time-marching procedure that is designed for the time-domain resolution of elastodynamic models considering their physical properties and adopted spatial discretizations. The technique is entirely automated and proves itself to be highly effective, featuring second-order accuracy, adaptive algorithmic dissipation and extended stability limits. Additionally, the discussed methodology is truly explicit, truly selfstarting, and it incorporates automated subdomain/sub-cycling splitting procedures to enhance its overall performance. Thus, the algorithm automatically divides the domain of the problem into different subdomains, adjusting their time-step values according to the properties of the discretized model, which allows improving the efficiency and the accuracy of the analysis, while ensuring stability. Locally-defined adaptive time-integration parameters are also considered, establishing an entirely self-adjustable formulation. In this case, expressions for the timeintegration parameters are provided based on the local features of the discrete model, allowing to create a further link between the adopted temporal and spatial discretization procedures, better counterbalancing their errors. These parameters are locally formulated to nullify the bifurcation spectral radius of the method at pre-established sampling frequencies, providing maximal numerical damping at the highest sampling frequency of the elements of the adopted spatial discretization. This design optimizes the formulation to mitigate the influence of spurious high-frequency modes on the computed responses, allowing for enhanced analyses. In fact, the primary goal of introducing numerical damping is to eliminate non-physical spurious oscillations that may arise from the excitation of spatially unresolved modes. Therefore, the methodology not only tracks down the frequency range of the discretized model, but also it is designed to adaptively enforce significantly low values (close to zero) for the spectral radius of the method at the highest frequencies of the model, as well as it aims to provide relatively high spectral radius values (close to one, considering physically undamped models) in the important low-frequency range. Benchmark analyses are conducted at the end of this study to demonstrate the technique's effectiveness taking into account theoretical problems and complex models that are representative of real-world applications in the OIL & GAS industry.

  Abstract
  This study discusses an explicit time-marching procedure that is designed for the time-domain resolution of elastodynamic models considering their physical properties and [...]

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• An enhanced fully-adaptive explicit-implicit time-marching formulation for elastodynamics

  D. Soares, L. Pinto, I. Sales, W. Mansur

  WCCM2024.

  
  

  Abstract

  In this work, an explicit-implicit time-marching formulation, which adapts to the model's properties, its adopted spatial and temporal discretizations, and its computed responses, is studied for elastodynamic analyses. Explicit-implicit approaches have become referred to as effective time-domain solution methodologies since they allow to combine the advantageous features of both explicit and implicit formulations, such as reduced solver efforts and guaranteed stability, providing very attractive techniques.

  Abstract
  In this work, an explicit-implicit time-marching formulation, which adapts to the model's properties, its adopted spatial and temporal discretizations, and its computed responses, [...]

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• Non-destructive stress wave amplitude testing for interface bonding strength of 3D printable concrete

  C. Qi, Y. Wu, P. Zhi

  WCCM2024.

  
  

  Abstract

  The aim of this study is to investigate the impact of interface bonding properties of 3D printable concrete (3DPC) on non-destructive testing. By fabricating concrete specimens with varying numbers of layers and employing ultrasonic devices for non-destructive testing, it was observed that the presence of interface layers results in 3DPC exhibiting smaller wave amplitudes compared to conventionally cast concrete. Moreover, with an increase in printing layers, there is a trend of initial growth followed by a decline in interface bonding strength, accompanied by changes in amplitude attenuation. Through the use of non-destructive testing methods and by observing the pattern of amplitude decay, the interface bonding properties of 3DPC were investigated. The results indicate that, compared to conventionally cast concrete, 3DPC prepared using additive manufacturing techniques significantly affects the propagation of stress waves due to interface layers, and there exists a linear relationship between interface bonding strength and wave amplitude loss. This may also be a fundamental factor contributing to differences in non-destructive testing outcomes.

  Abstract
  The aim of this study is to investigate the impact of interface bonding properties of 3D printable concrete (3DPC) on non-destructive testing. By fabricating concrete specimens [...]

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• Estimation of grinding contact stiffness and damping parameters from dynamic output only using Hunt-Crossley force model and Unscented Kalman filter

  V. Vu, Q. Nguyen, M. Thomas

  WCCM2024.

  
  

  Abstract

  . This paper introduces a novel approach that combines the Unscented Kalman Filter with the Hunt-Crossley force model to accurately estimate the stiffness and damping characteristics at the contact point of a grinding process conducted by a flexible manipulator. The Hunt-Crossley force model is proposed for the force contact considering the flexibility of the manipulator structure and is written in a state form as functions of the contact stiffness and damping. Leveraging the Unscented Transform to linearize the nonlinear measurement functions, the Unscented Kalman Filter effectively estimates and updates the stiffness and damping parameters based on the state model. This method is put into practice in a real grinding scenario employing a flexible manipulator. Its practicality and convenience make it a promising technique for estimating operational machining parameters and developing an efficient vibration control strategy for machining applications.

  Abstract
  . This paper introduces a novel approach that combines the Unscented Kalman Filter with the Hunt-Crossley force model to accurately estimate the stiffness and damping characteristics [...]

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• A study on the structural systems with tapered hardening-type hysteresis devices

  A. Noda, T. Maegawa, S. Mitsui, M. Sasatani

  WCCM2024.

  
  

  Abstract

  The Japanese seismic design code allows for formation of plastic hinges at beam ends during large earthquakes. However, in cases in which seismic motion exceeds anticipated levels, seismic energy surpassing the structure’s absorption capacity may result in partial destruction, ultimately leading to the collapse of the whole building. Unexpected damage to buildings may also occur if they are subjected to long-period ground motions. To prevent such damage, we propose a displacement control device with hardening-type hysteresis. We performed experiments and analysis to verify the performance.

  Abstract
  The Japanese seismic design code allows for formation of plastic hinges at beam ends during large earthquakes. However, in cases in which seismic motion exceeds anticipated [...]

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• Dynamic displacement recognition of frame structures based on computer vision

  M. He, J. He, X. Sun

  WCCM2024.

  
  

  Abstract

  Displacement induced by external forces is one of the most intuitive variables for assessing structural safety. Traditional contact methods, such as deploying displacement sensors on structures, are often limited by objective factors. Non-contact methods, such as utilizing computer vision algorithms like optical flow estimation and feature matching, offer the advantages of rapid and accurate structural displacement acquisition, unaffected by the structure itself and quick deployment. However, enhancing the accuracy of displacement monitoring based on computer vision remains a focal point in this field of study. In this paper, based on experimental data from a vibration table testing a four-layer reinforced concrete framework under three different conditions, we propose a method for processing dynamic displacement data that combines non-contact and contact approaches. This method integrates dynamically recognized structural displacements based on computer vision technology with data recorded by acceleration sensors on the structure to enhance displacement monitoring accuracy. The research results demonstrate that our method can obtain structural dynamic displacements based on computer vision information, confirming the effectiveness and reliability of our approach.

  Abstract
  Displacement induced by external forces is one of the most intuitive variables for assessing structural safety. Traditional contact methods, such as deploying displacement [...]

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• Study of wind-induced vibrations on a trellis pylon controlled through an active mass damper system

  F. Ripamonti, S. Cii, A. Bussini

  WCCM2024.

  
  

  Abstract

  The rapid expansion of telecommunications infrastructure, driven by the deployment of the 5G network, necessitates innovative engineering solutions to ensure the reliability and stability of these critical structures. Steel trellis pylons, designed for hosting several telecommunication antennas, are particularly susceptible to wind-induced vibrations due to their slender profiles, high equivalent area exposed to wind loads and low structural damping. Such vibrations can lead to structural deterioration, signal disturbance, and, in severe cases, total structural failure. In this context, the need for effective vibration control measures is becoming more and more relevant. This paper underscores the complex challenge of windinduced vibrations in telecommunications pylons and the promising potential of AMD systems as a mitigation strategy. This study aims at advancing the state of the art by integrating experimental wind load measurements, modal analysis, and the application of AMD technology to a 50-meter-high steel trellis pylon. Through comprehensive analysis and numerical simulation, the effectiveness of AMD systems in enhancing structural performance and resilience under wind loading conditions is validated.

  Abstract
  The rapid expansion of telecommunications infrastructure, driven by the deployment of the 5G network, necessitates innovative engineering solutions to ensure the reliability [...]

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• Mathematical and experimental modeling of a Stockbridge damper used to suppress Aeolian vibration of transmission line conductors

  Z. Zondi, T. Ngonda, M. Kaunda, R. Stephen

  WCCM2024.

  
  

  Abstract

  The asymmetric Stockbridge vibration damper is commonly employed in overhead power cables to mitigate Aeolian vibration, which is the oscillation of conductor cables within the 3–150 Hz frequency range. The damper's effectiveness is determined by its resonant frequencies, which increase power dissipation to exceed the wind-induced power input. While the basic symmetric Stockbridge damper has two resonant frequencies, the asymmetric version can exhibit up to four. Previous studies have shown that changes in the counterweight's geometry can increase the natural frequencies. This paper presents experiments on a modified asymmetric damper and uses an analytical model from Vaja et al. (2018), to confirm their findings. employed in overhead transmission lines to mitigate Aeolian vibration

  Abstract
  The asymmetric Stockbridge vibration damper is commonly employed in overhead power cables to mitigate Aeolian vibration, which is the oscillation of conductor cables within [...]

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• Weight reduction in dynamically loaded systems through the effect of damping in bolted joints

  S. Roediger, C. Koenke, H. Beinersdorf

  WCCM2024.

  
  

  Abstract

  In order to reduce vibration amplitudes, the MFPA Weimar is investigating joint damping. The effect is based on the relative displacement between two components between which a surface pressure acts. In this case, the surface pressure is applied by a bolted connection. The damping behavior is dependent on normal force and amplitude. Decay tests clearly show that it is not possible to approximate the curves due to the viscous behavior (exponential decay function). The superposition with Coloumb's friction leads to a new damping model, especially in the initial range. The aim is to set up a numerical model in order to be able to take the local damping effects into account in the development of components. For this purpose, zero thickness elements (ZTE) are introduced into the joint in the FE simulation and provided with a constitutive model that can represent the energy dissipation. The ZTEs are parameterized as a function of material, surface pressure and surface roughness. The amplitude reduction, which is often achieved by a frequency shift of the natural frequencies via tuned mass dampers, is replaced and thus contributes to lightweight construction.

  Abstract
  In order to reduce vibration amplitudes, the MFPA Weimar is investigating joint damping. The effect is based on the relative displacement between two components between which [...]

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