On Model- and Data-based Approaches to Structural Health Monitoring

Structural Heath Monitoring (SHM) is the term applied to the process of periodically monitoring the state of a structural system with the aim of diagnosing damage in the structure. Over the course of the past several decades there has been ongoing interest in approaches to the problem of SHM. This attention has been sustained by the belief that SHM will allow substantial economic and life-safety benefits to be realised across a wide range of applications. Several numerical and laboratory implementations have been successfully demonstrated. However, despite this research effort, real-world applications of SHM as originally envisaged are somewhat rare. Numerous technical barriers to the broader application of SHM methods have been identified, namely: severe restrictions on the availability of damaged-state data in real-world scenarios; difficulties associated with the numerical modelling of physical systems; and limited understanding of the physical effect of system inputs (including environmental and operational loads). This thesis focuses on the roles of law-based and data-based modelling in current applications of. First, established approaches to model-based SHM are introduced, with the aid of an exemplar ‘wingbox’ structure. The study highlights the degree of difficulty associated with applying model-updating-based methods and with producing numerical models capable of accurately predicting changes in structural response due to damage. These difficulties motivate the investigation of non-deterministic, predictive modelling of structural responses taking into account both experimental and modelling uncertainties. Secondly, a data-based approach to multiple-site damage location is introduced, which may allow the quantity of experimental data required for classifier training to be drastically reduced. A conclusion of the above research is the identification of hybrid approaches, in which a forward-mode law-based model informs a data-based damage identification scheme, as an area for future wor

Nonlinearities of an aircraft Piccolo tube: Identification and modeling

Piccolo tubes are parts of aircraft wings anti-icing system and consist of titanium pipes inserted into the internal structure of the slat. Due to differential thermal expansion, clearances between the tube and its support are unavoidable and cause the overall system to exhibit highly nonlinear behavior, resulting from impacts and friction. This paper addresses the identi cation and modeling of the nonlinearities present in the slat-Piccolo tube connection. The complete identi cation procedure, from nonlinearity detection and characterization to parameter estimation, is carried out based upon sine-sweep measurements. The use of several techniques, such as the acceleration surface method, enables to understand the complex dynamics of the Piccolo tube and build a reliable model of its nonlinearities. In particular, the parameters of nonsmooth nonlinear stiffness and damping mechanisms are estimated. The nonlinear model is finally validated on standard quali cation tests for airborne equipments

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The effect of attenuation on the identification of impact damage in CFRP laminates

The subject of this study is the identification of impact damage in composite materials on the basis of response-only measurements. Low velocity impact events can lead to barely visible damage in composite structures which if left undetected can lead to degradation of performance and, in the worst case, to catastrophic failure of the structure. The increasing use of composite materials in aerospace and renewable energy applications motivates a desire to develop methods that allow detection of impact and identification of any resulting damage using measured responses only. In previous work it has been shown that low-dimensional ‘features’ drawn from surface mounted sensors may be used to develop a statistical basis for damage identification for Carbon Fibre-Reinforced Polymer (CFRP) coupon samples subjected to impact via a drop-test machine. This work has shown that not only can such features be used to indicate the presence of damage, but also that they show promise in indicating both the nature and extent of the damage that has occurred. There are several questions outstanding with regards to this method of damage identification. Prominent among these is the question of attenuation of the signal as it passes through the structure and whether this will hinder the practical application of the methodology. Attenuation is a particular concern given the nature of the composite materials under investigation, being both moderately damped and orthotropic in nature. In the present study, the effect of attenuation is investigated through a series of experiments on extensive plates with sensors at varying locations and orientations from the point of impact

35th IMAC, A Conference and Exposition on Structural Dynamics 2017

Nonlinear Dynamics, Volume 1: Proceedings of the 35th IMAC, A Conference and Exposition on Structural Dynamics, 2017, the first volume of ten from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Nonlinear Dynamics, including papers on: Nonlinear System Identification Nonlinear Modeling &amp; Simulation Nonlinear Reduced-order Modeling Nonlinearity in Practice Nonlinearity in Aerospace Systems Nonlinearity in Multi-Physics Systems Nonlinear Modes and Modal Interactions Experimental Nonlinear Dynamics.Special Topics in Structural Dynamics, Volume 6: Proceedings of the 35th IMAC, A Conference and Exposition on Structural Dynamics, 2017, the sixth volume of ten from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Structural Dynamics, including papers on: Experimental Methods Analytical Methods General Dynamics & Modal Analysis General Dynamics & System Identification Damage Detection .Structural Health Monitoring & Damage Detection, Volume 7: Proceedings of the 35th IMAC, A Conference and Exposition on Structural Dynamics, 2017, the seventh volume of ten from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Structural Health Monitoring & Damage Detection, including papers on: Structural Health Monitoring Damage Detection System Identification Active Controls.Rotating Machinery, Hybrid Testing, Vibro-Acoustics & Laser Vibrometry, Volume 8: Proceedings of the 35th IMAC, A Conference and Exposition on Structural Dynamics, 2017, the eighth volume of ten from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Rotating Machinery, Hybrid Testing, Vibro-Acoustics & Laser Vibrometry, including papers on: Rotating Machinery Vibro-Acoustics Experimental Techniques Advances in Wind Energy Scanning Laser Doppler Vibrometry Methods Hybrid Test Methods.Topics in Modal Analysis & Testing, Volume 10: Proceedings of the 35th IMAC, A Conference and Exposition on Structural Dynamics, 2017, the tenth volume of ten from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Modal Analysis, including papers on: Operational Modal & Modal Analysis Applications Experimental Techniques Modal Analysis, Measurements & Parameter Estimation Modal Vectors & Modeling Basics of Modal Analysis Additive Manufacturing & Modal Testing of Printed Parts

Vibration-based structural health monitoring using large sensor networks

info:eu-repo/semantics/publishe