Damage localization and quantification of composite stratified beam structures using residual force method

10.1088/1742-6596/842/1/012028Journal of Physics: Conference Series84211202

Finite Element Modelling and Damage Detection of Seam Weld

© Springer Nature Singapore Pte Ltd 2020. Seam welds are widely used in assembled structures for connecting components. However, the dynamic effects of a seam weld are often difficult to characterise in numerical models for several reasons: (1) it is often not wise to build a fine mesh on the seam line which will add considerable computational cost for a structure with many welds, (2) the mechanical properties of weld materials are not well known; (3) sometimes some geometric information about welds is not known beforehand. In this work, the finite element model of a welding connection part is developed by employing CSEAM element in NASTRAN and its feasibility for representing a seam weld is investigated. Based on this result, a damage detection method by updating the properties of the built CSEAM elements is also proposed for welding quality assurance. The damage takes the form of a gap in the weld which causes a sharp change of model strain energy at the edges of the gap for certain vibration modes. Specifically, the model strain energy shape is used as the objective function. A Kriging model is introduced for efficiency and simulation of a T-shaped welded plate structure to demonstrate the effectiveness of this method

Railway bridge structural health monitoring and fault detection: state-of-the-art methods and future challenges

Railway importance in the transportation industry is increasing continuously, due to the growing demand of both passenger travel and transportation of goods. However, more than 35% of the 300,000 railway bridges across Europe are over 100-years old, and their reliability directly impacts the reliability of the railway network. This increased demand may lead to higher risk associated with their unexpected failures, resulting safety hazards to passengers and increased whole life cycle cost of the asset. Consequently, one of the most important aspects of evaluation of the reliability of the overall railway transport system is bridge structural health monitoring, which can monitor the health state of the bridge by allowing an early detection of failures. Therefore, a fast, safe and cost-effective recovery of the optimal health state of the bridge, where the levels of element degradation or failure are maintained efficiently, can be achieved. In this article, after an introduction to the desired features of structural health monitoring, a review of the most commonly adopted bridge fault detection methods is presented. Mainly, the analysis focuses on model-based finite element updating strategies, non-model-based (data-driven) fault detection methods, such as artificial neural network, and Bayesian belief network–based structural health monitoring methods. A comparative study, which aims to discuss and compare the performance of the reviewed types of structural health monitoring methods, is then presented by analysing a short-span steel structure of a railway bridge. Opportunities and future challenges of the fault detection methods of railway bridges are highlighted

A Critical Review on the Structural Health Monitoring Methods of the Composite Wind Turbine Blades

With increasing turbine size, monitoring of blades becomes increasingly im-portant, in order to prevent catastrophic damages and unnecessary mainte-nance, minimize the downtime and labor cost and improving the safety is-sues and reliability. The present work provides a review and classification of various structural health monitoring (SHM) methods as strain measurement utilizing optical fiber sensors and Fiber Bragg Gratings (FBG’s), active/ pas-sive acoustic emission method, vibration‒based method, thermal imaging method and ultrasonic methods, based on the recent investigations and prom-ising novel techniques. Since accuracy, comprehensiveness and cost-effectiveness are the fundamental parameters in selecting the SHM method, a systematically summarized investigation encompassing methods capabilities/ limitations and sensors types, is needed. Furthermore, the damages which are included in the present work are fiber breakage, matrix cracking, delamina-tion, fiber debonding, crack opening at leading/ trailing edge and ice accre-tion. Taking into account the types of the sensors relevant to different SHM methods, the advantages/ capabilities and disadvantages/ limitations of repre-sented methods are nominated and analyzed

Modal analysis of multi-reference impact test data for steel stringer bridges

A comparative study on the postprocessing of experimental modal data from a full scale steel stringer bridge for damage identification is presented. The bridge was tested before and after removal of one of the bearing plates at one abutment. Frequency Response Functions, measured crt different spatial locations, are used to post-process the data using a Complex Mode Indicator function(CMIF) algorithm. Dynamic properties of the bridge show major differences between the two cases. In addition modal flexibility of the bridge is calculated for the measured degrees of freedom. Modal flexibility of the bridge shows good agreement with static instrumentation results under truck loading. The induced damage is successfully quantified for this loading case. The ''after-removal'' condition data was also post-processed at Los Alamos National Laboratory using the Eigensystem Realization Algorithm (ERA) in order to provide a distant check and correlation for the results. This paper briefly describes the two different algorithms and presents the results in both modal and flexibility space. Further the principal focus of this paper is the post-processing algorithms and one damage index, although a number of different damage identification indices are being used for varying levels and types of damage as part of the ongoing research project

Experimental Assessment of a Modal-Based Multi-Parameter Method for Locating Damage in Composite Laminates

The low specific weight of composite materials, together with their excellent mechanical properties, make them suitable to be widely used in many modern engineering structures. However, composite materials are quite sensitive to impacts: a specific kind of damage, called Barely Visible Impact Damage (BVID), may occur, constituting an unsafe failure of difficult assessment. In the past few years several methods have been developed aiming at assessing this type of damage. In this paper, a vibration-based technique that combines both the natural frequencies and the modal damping factors as damage sensitive features is tested for locating impact damage in carbon fibre reinforced laminates. The method is intended to be used for locating damage in real laminated composite structures that undergo in-service impacts, such as an airplane's fuselage or wings. Assessing a minimum of one response coordinate is the strict requirement during each inspection, because it uses the dynamic global parameters of the structure as damage features. This is possible because the method assumes that, at least for BVID, the mode shapes remain practically unchanged. The theory is summarized and the method is tested using experimental setups where damage is introduced at different locations. Additionally, the hypothesis that different damage morphologies on composite materials have different contributions to the damage features is addressed.Peer reviewedFinal Accepted Versio

Localization of a delamination and estimation of its length in a composite laminate beam by the VSHM and pattern recognition methods

The focus of this work is to investigate the delamination damage in laminate composite beams, to fix a Vibration-based Structural Health Monitoring (VSHM) method for the laminate structures. The analysis is concentrated on the vibration characteristics of the samples and, in particular, the attention is addressed on the first several natural frequencies of a composite laminate beam with a delamination damage. The core of this work is an experimental investigation on the vibration response of a composite laminate beam and its changes caused by delaminations with different sizes and in different locations of the beam. The study is divided in 3 sections: delamination detection, delamination localization, and delamination estimate. The aim is to determine how the first six harmonics frequencies change due to the delamination, and the results show that they can be successfully used to investigate the presence, the location and the dimensions of the delamination in a composite beam. A Pattern Recognition analysis is used to locate the damage, while the detection and the evaluation are done using the changes in the harmonic frequencies. A finite element analysis is performed, and the variations of the natural frequencies due to delamination are in good agreement with the experimental results

Experimental localization of small damages using modal filters

info:eu-repo/semantics/publishe