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Developing health indicators for composite structures based on a two-stage semi-supervised machine learning model using acoustic emission data

Moradi, M. (author), Chiachío, Juan (author), Zarouchas, D. (author)

Composite structures are highly valued for their strength-to-weight ratio, durability, and versatility, making them ideal for a variety of applications, including aerospace, automotive, and infrastructure. However, potential damage scenarios like impact, fatigue, and corrosion can lead to premature failure and pose a threat to safety. This...

conference paper 2023

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Advanced Health Monitoring of Composite Structures Through Deep Learning-Based Analysis of Lamb Wave Data for Developing Health Indicators

Moradi, M. (author), Gul, F.C. (author), Chiachío, Juan (author), Benedictus, R. (author), Zarouchas, D. (author)

A health indicator (HI) serves as an intermediary link between structural health monitoring (SHM) data and prognostic models, and an efficient HI should meet prognostic criteria, i.e., monotonicity, trendability, and prognosability. However, designing a proper HI for composite structures is a challenging task due to the complex damage...

conference paper 2023

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Non-destructive strength prediction of composite laminates utilizing deep learning and the stochastic finite element methods

Nastos Konstantopoulos, C. (author), Komninos, P. (author), Zarouchas, D. (author)

A hybrid methodology based on numerical and non-destructive experimental schemes, which is able to predict the structural level strength of composite laminates is proposed on the current work. The main objective is to predict the strength by substituting the up to failure experiments with non-destructive experiments where the investigated...

journal article 2023

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Acoustic emission-based remaining useful life prognosis of aeronautical structures subjected to compressive fatigue loading

Galanopoulos, Georgios (author), Milanoski, Dimitrios (author), Eleftheroglou, N. (author), Broer, Agnes A.R. (author), Zarouchas, D. (author), Loutas, Theodoros (author)

An increasing interest for Structural Health Monitoring has emerged in the last decades. Acoustic emission (AE) is one of the most popular and widely studied methodologies employed for monitoring, due to its capabilities of detecting, locating and capturing the evolution of damage. Most literature so far, has employed AE for characterizing...

journal article 2023

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A data driven methodology for upscaling remaining useful life predictions: From single- to multi-stiffened composite panels

Galanopoulos, Georgios (author), Fytsilis, Efthimios (author), Yue, N. (author), Broer, Agnes A.R. (author), Milanoski, Dimitrios (author), Zarouchas, D. (author), Loutas, Theodoros (author)

In this paper we execute a complex test campaign to develop a novel methodology for the Remaining Useful Life (RUL) estimation of complex multi-stiffened composite aeronautical panels utilizing Machine Learning models trained with Structural Health Monitoring (SHM) data from hierarchically simpler elements, i.e., single-stiffened panels....

journal article 2023

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Hierarchical Upscaling of Data-Driven Damage Diagnostics for Stiffened Composite Aircraft Structures

Broer, Agnes A.R. (author), Yue, N. (author), Galanopoulos, Georgios (author), Benedictus, R. (author), Loutas, Theodoros (author), Zarouchas, D. (author)

To move towards a condition-based maintenance practice for aircraft structures, design of reliable health management methodologies is required. Development of diagnostic methodologies is commonly realised on simplified sample structures with assumptions that methodologies can be adapted for application to realistic aircraft structures under...

conference paper 2023

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Intelligent Health Indicators Based on Semi-supervised Learning Utilizing Acoustic Emission Data

Moradi, M. (author), Broer, Agnes A.R. (author), Chiachío, Juan (author), Benedictus, R. (author), Zarouchas, D. (author)

Health indicators are indices that act as intermediary links between raw SHM data and prognostic models. An efficient HI should satisfy prognostic requirements such as monotonicity, trendability, and prognosability in such a way that it can be effectively used as an input in a prognostic model for remaining useful life estimation. However,...

conference paper 2023

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Notched Beam Test for SHCC-Concrete Interface

Mustafa, S. (author), Harrass, Othman (author), Lukovic, M. (author)

The number of hybrid concrete structures is increasing due to the need for repairing/strengthening existing structures and the development of new hybrid concrete systems. The structural response of these hybrid structures might be governed by the strength of the interface between the two concretes, making it essential to characterize the...

conference paper 2023

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Sensitivity analysis for buckling characterisation using the vibration correlation technique

Baciu, Theodor D. (author), Degenhardt, Richard (author), Franzoni, Felipe (author), Gliszczynski, Adrian (author), Arbelo, Mariano A. (author), Castro, Saullo G.P. (author), Kalnins, Kaspars (author)

The Vibration Correlation Technique (VCT) is a non-destructive method to predict buckling loads for imperfection-sensitive structures. While successfully used to validate numerical models and predict experimental buckling loads, recommendations for defining the VCT experiment are scarce. Here, its sensitivity towards the number of load steps...

journal article 2023

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Intelligent health indicator construction for prognostics of composite structures utilizing a semi-supervised deep neural network and SHM data

Moradi, M. (author), Broer, Agnes A.R. (author), Chiachío, Juan (author), Benedictus, R. (author), Loutas, Theodoros H. (author), Zarouchas, D. (author)

A health indicator (HI) is a valuable index demonstrating the health level of an engineering system or structure, which is a direct intermediate connection between raw signals collected by structural health monitoring (SHM) methods and prognostic models for remaining useful life estimation. An appropriate HI should conform to prognostic...

journal article 2023

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A novel strain-based health indicator for the remaining useful life estimation of degrading composite structures

Galanopoulos, Georgios (author), Eleftheroglou, N. (author), Milanoski, Dimitrios (author), Broer, Agnes A.R. (author), Zarouchas, D. (author), Loutas, Theodoros (author)

We present a generic methodology for developing a Health Indicator out of strain-based Structural Health Monitoring data suitable for implementation in prognostic tasks. For this purpose, an in-house test campaign is launched. Single-stringered composite panels are subjected to compression-compression fatigue with the strains being monitored...

journal article 2023

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Experimental study of post-buckled single-stringer composite specimens under fatigue loads with different load levels and load ratios

Paz Mendez, J. (author), Raimondo, A. (author), Bisagni, C. (author)

This study aims at better understanding the damage tolerance of stiffened composite panels subjected to fatigue loads in the post-buckling regime. Ten single-stringer hat-stiffened specimens with an initial delamination between the skin and the stringer foot were manufactured, and then tested under quasi-static and fatigue loads in post...

journal article 2023

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BIOS: an object-oriented framework for Surrogate-Based Optimization using bio-inspired algorithms

Barroso, Elias Saraiva (author), Ribeiro, Leonardo Gonçalves (author), Alves Maia, M. (author), Rocha, I.B.C.M. (author), Parente, Evandro (author), de Melo, Antônio Macário Cartaxo (author)

This paper presents BIOS (acronym for Biologically Inspired Optimization System), an object-oriented framework written in C++, aimed at heuristic optimization with a focus on Surrogate-Based Optimization (SBO) and structural problems. The use of SBO to deal with structural optimization has grown considerably in recent years due to the...

journal article 2022

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Probabilistic failure analysis of quasi-isotropic CFRP structures utilizing the stochastic finite element and the Karhunen–Loève expansion methods

Nastos Konstantopoulos, C. (author), Zarouchas, D. (author)

The accuracy of structural analysis in composite structures depends on the proper estimation of the uncertainties mainly related to the mechanical properties of the constituent materials. On this basis, a sophisticated numerical tool is proposed, able to perform stochastic finite element analysis on composite structures with material...

journal article 2022

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Buckling-driven mechanisms for twisting control in adaptive composite wings

Zhang, J. (author), Bisagni, C. (author)

This study aims to design novel tailorable and effective mechanisms by controlling buckling behaviour in structural elements of a composite wing for future morphing application. Instead of the traditional design against buckling, the idea is to embrace this built-in instability by using the nonlinear post-buckling response to control...

journal article 2021

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Acoustic emission source location using Lamb wave propagation simulation and artificial neural network for I-shaped steel girder

Cheng, L. (author), Xin, H. (author), Groves, R.M. (author), Veljkovic, M. (author)

Acoustic emission (AE) is often used for structural health monitoring (SHM) in the wide field of engineering structures and one of its most beneficial attributes is the ability to localize the damage/crack based on the AE events. The vast majority of ongoing work on AE monitoring focues on geometrically simple structures or a confined area,...

journal article 2021

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Achievements in the buckling of thin-walled composite launcher structures

Degenhardt, Richard (author), Franzoni, Felipe (author), Castro, Saullo G.P. (author)

For most structural parts of real launcher structures buckling is the critical design criterion. Due to the high imperfection sensitivity of these structures and to the unknown geometric imperfections during the design phase, it is still today a challenge to predict a reliable design buckling load and to experimentally and non-destructively...

conference paper 2021

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Fatigue analysis of a post-buckled composite single-stringer specimen taking into account the local stress ratio

Raimondo, A. (author), Bisagni, C. (author)

The fatigue life prediction of post-buckled composite structures represents still an unresolved issue due to the complexity of the phenomenon and the high costs of experimental testing. In this paper, a novel numerical approach, called “Min-Max Load Approach”, is used to analyze the behavior of a composite single-stringer specimen with an...

journal article 2020

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Weight trades in the design of a composite wing box: Effect of various design choices

Moors, Gunther (author), Kassapoglou, C. (author), de Almeida, Sergio Frascino Müller (author), Ferreira, Clovis Augusto Eça (author)

A process to efficiently design composite wing boxes is presented. It uses analytical and semi-empirical equations for failure modes such as material strength, plate buckling, stiffener column buckling and stiffener flange or web crippling. Laminate layups for the different components are selected in accordance with basic engineering rules...

journal article 2019

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Structural health monitoring data fusion for in-situ life prognosis of composite structures

Eleftheroglou, N. (author), Zarouchas, D. (author), Loutas, Theodoros (author), Alderliesten, R.C. (author), Benedictus, R. (author)

A novel framework to fuse structural health monitoring (SHM) data from different in-situ monitoring techniques is proposed aiming to develop a hyper-feature towards more effective prognostics. A state-of-the-art Non-Homogenous Hidden Semi Markov Model (NHHSMM) is utilized to model the damage accumulation of composite structures, subjected to...

journal article 2018