Smart Manufacturing in Rolling Process Based on Thermal Safety Monitoring by Fiber Optics Sensors Equipping Mill Bearings

The steel rolling process is critical for safety and maintenance because of loading and thermal operating conditions. Machinery condition monitoring (MCM) increases the system’s safety, preventing the risk of fire, failure, and rupture. Equipping the mill bearings with sensors allows monitoring of the system in service and controls the heating of mill components. Fiber optic sensors detect loading condition, vibration, and irregular heating. In several systems, access to machinery is rather limited. Therefore, this paper preliminarily investigates how fiber optics can be effectively embedded within the mill cage to set up a smart manufacturing system. The fiber Bragg gratings (FBG) technology allows embedding sensors inside the pins of backup bearings and performing some prognosis and diagnosis activities. The study starts from the rolling mill layout and defines its accessibility, considering some real industrial cases. Testing of an FBG sensor prototype checks thermal monitoring capability inside a closed cavity, obtained on the surface of either the fixed pin of the backup bearing or the stator surrounding the outer ring. Results encourage the development of the whole prototype of the MCM system to be tested on a real mill cage in full operation

A Review of Structural Health Monitoring Techniques as Applied to Composite Structures.

Structural Health Monitoring (SHM) is the process of collecting, interpreting, and analysing data from structures in order to determine its health status and the remaining life span. Composite materials have been extensively use in recent years in several industries with the aim at reducing the total weight of structures while improving their mechanical properties. However, composite materials are prone to develop damage when subjected to low to medium impacts (ie 1 – 10 m/s and 11 – 30 m/s respectively). Hence, the need to use SHM techniques to detect damage at the incipient initiation in composite materials is of high importance. Despite the availability of several SHM methods for the damage identification in composite structures, no single technique has proven suitable for all circumstances. Therefore, this paper offers some updated guidelines for the users of composites on some of the recent advances in SHM applied to composite structures; also, most of the studies reported in the literature seem to have concentrated on the flat composite plates and reinforced with synthetic fibre. There are relatively fewer stories on other structural configurations such as single or double curve structures and hybridised composites reinforced with natural and synthetic fibres as regards SHM

The Public Service Media and Public Service Internet Manifesto

This book presents the collectively authored Public Service Media and Public Service Internet Manifesto and accompanying materials.The Internet and the media landscape are broken. The dominant commercial Internet platforms endanger democracy. They have created a communications landscape overwhelmed by surveillance, advertising, fake news, hate speech, conspiracy theories, and algorithmic politics. Commercial Internet platforms have harmed citizens, users, everyday life, and society. Democracy and digital democracy require Public Service Media. A democracy-enhancing Internet requires Public Service Media becoming Public Service Internet platforms – an Internet of the public, by the public, and for the public; an Internet that advances instead of threatens democracy and the public sphere. The Public Service Internet is based on Internet platforms operated by a variety of Public Service Media, taking the public service remit into the digital age. The Public Service Internet provides opportunities for public debate, participation, and the advancement of social cohesion. Accompanying the Manifesto are materials that informed its creation: Christian Fuchs’ report of the results of the Public Service Media/Internet Survey, the written version of Graham Murdock’s online talk on public service media today, and a summary of an ecomitee.com discussion of the Manifesto’s foundations

Structural Health Monitoring Damage Detection Systems for Aerospace

This open access book presents established methods of structural health monitoring (SHM) and discusses their technological merit in the current aerospace environment. While the aerospace industry aims for weight reduction to improve fuel efficiency, reduce environmental impact, and to decrease maintenance time and operating costs, aircraft structures are often designed and built heavier than required in order to accommodate unpredictable failure. A way to overcome this approach is the use of SHM systems to detect the presence of defects. This book covers all major contemporary aerospace-relevant SHM methods, from the basics of each method to the various defect types that SHM is required to detect to discussion of signal processing developments alongside considerations of aerospace safety requirements. It will be of interest to professionals in industry and academic researchers alike, as well as engineering students. This article/publication is based upon work from COST Action CA18203 (ODIN - http://odin-cost.com/), supported by COST (European Cooperation in Science and Technology). COST (European Cooperation in Science and Technology) is a funding agency for research and innovation networks. Our Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation

Diagnosis of low-speed bearing degradation using acoustic emission techniques

It is widely acknowledged that bearing failures are the primary reason for breakdowns in rotating machinery. These failures are extremely costly, particularly in terms of lost production. Roller bearings are widely used in industrial machinery and need to be maintained in good condition to ensure the continuing efficiency, effectiveness, and profitability of the production process. The research presented here is an investigation of the use of acoustic emission (AE) to monitor bearing conditions at low speeds. Many machines, particularly large, expensive machines operate at speeds below 100 rpm, and such machines are important to the industry. However, the overwhelming proportion of studies have investigated the use of AE techniques for condition monitoring of higher-speed machines (typically several hundred rpm, or even higher). Few researchers have investigated the application of these techniques to low-speed machines (<100 rpm), This PhD addressed this omission and has established which, of the available, AE techniques are suitable for the detection of incipient faults and measurement of fault growth in low-speed bearings. The first objective of this research program was to assess the applicability of AE techniques to monitor low-speed bearings. It was found that the measured statistical parameters successfully monitored bearing conditions at low speeds (10-100 rpm). The second objective was to identify which commonly used statistical parameters derived from the AE signal (RMS, kurtosis, amplitude and counts) could identify the onset of a fault in either race. It was found that the change in AE amplitude and AE RMS could identify the presence of a small fault seeded into either the inner or the outer races. However, the severe attenuation of the signal from the inner race meant that, while AE amplitude and RMS could readily identify the incipient fault, kurtosis and the AE counts could not. Thus, more attention needs to be given to analysing the signal from the inner race. The third objective was to identify a measure that would assess the degree of severity of the fault. However, once the defect was established, it was found that of the parameters used only AE RMS was sensitive to defect size. The fourth objective was to assess whether the AE signal is able to detect defects located at either the centre or edge of the outer race of a bearing rotating at low speeds. It is found that all the measured AE parameters had higher values when the defect was seeded in the middle of the outer race, possibly due to the shorter path traversed by the signal between source and sensor which gave a lower attenuation than when the defect was on the edge of the outer race. Moreover, AE can detect the defect at both locations, which confirmed the applicability of the AE to monitor the defects at any location on the outer race

Non-Destructive Techniques for the Condition and Structural Health Monitoring of Wind Turbines: A Literature Review of the Last 20 Years

A complete surveillance strategy for wind turbines requires both the condition monitoring (CM) of their mechanical components and the structural health monitoring (SHM) of their load-bearing structural elements (foundations, tower, and blades). Therefore, it spans both the civil and mechanical engineering fields. Several traditional and advanced non-destructive techniques (NDTs) have been proposed for both areas of application throughout the last years. These include visual inspection (VI), acoustic emissions (AEs), ultrasonic testing (UT), infrared thermography (IRT), radiographic testing (RT), electromagnetic testing (ET), oil monitoring, and many other methods. These NDTs can be performed by human personnel, robots, or unmanned aerial vehicles (UAVs); they can also be applied both for isolated wind turbines or systematically for whole onshore or offshore wind farms. These non-destructive approaches have been extensively reviewed here; more than 300 scientific articles, technical reports, and other documents are included in this review, encompassing all the main aspects of these survey strategies. Particular attention was dedicated to the latest developments in the last two decades (2000–2021). Highly influential research works, which received major attention from the scientific community, are highlighted and commented upon. Furthermore, for each strategy, a selection of relevant applications is reported by way of example, including newer and less developed strategies as well

Structural Health Monitoring of complex structures based on propagation and scattering of Guided Ultrasonic Waves in composite media

The major concern of aerospace and transportation engineering during the last years has been related to increase performances and safety with energy savings. Composite materials have been indeed widely adopted with the aim to design high performance and lighter components. However, random events such as certain low velocity impacts may induce barely visible or not visible failure due to their complex mechanics behavior. Impact induced damages in stiffened composite structures are usually accommodated with constrained design and strictly maintenance tasks which increase operational costs above all else and decrease the advantages for which composites have been massively introduced. To overcome such drawbacks, an integrated structure providing monitoring of critical components appears a reasonable solution. A condition based approach could be able to relax the maintenance strategy minimizing aircraft downtime as well. Moreover the design constraints would be avoided further increasing the structural performance with a more ecological friendly aircraft. Although this is a very long time perspective, for the first demand Structural Health Monitoring (SHM) systems, providing information about the structural efficiency, appear to be the best solution. Within this context, the work deals with detection, localization and size assessment of sudden failures like delamination and disbondings with on-line monitoring technique by permanently attached piezoelectric transducers (PZT) capable to excite and sense guided ultrasonic waves. Composite stiffened structures typically designed for aircraft wing-box are mainly investigated. Delamination between several layers and disbondings are carried out inducing low velocity impacts with the attempt to analyze different and complex damage scenarios. Two different approaches are mainly proposed. Anti-symmetric propagation based technique (global approach) using the A0 Lamb wave mode for interrogation demand is first presented to obtain a fast end effective localization of damage, no matter the failure type is. A reliable solution is also provided using a multi-parameter approach to increase the probability of detection. The obtained algorithm is implemented in a graphic user interface developed and coded by the author. Different features, including customized selection of ultrasonic time histories, statistical threshold definition and interactive tools for self-diagnosis of sensors and complex geometry representation are developed to obtain an effective tool for global damage diagnosis. Although the promising results obtained with a fewer computational time required respect to classic tomographic approaches, size and severity of damage can be assessed only statistically relating the metric adopted to the flaw dimension. However, their deterministic assessment is crucial where the stringers adopted to reinforce thin walled structures are affected by not visible disbondings. This fact leads to the separation between the stiffener and the hosting structure preventing the collaboration between parts with a dangerous drawback for loading absorbing. For the last demand, usually disbonding stoppers are designed to prevent critical decrease of load carrying capacity below the limit design loads. Towards a condition based approach, a novel detection technique capable to predict arrival time of guided waves redirectedbby stringers to detect any possible change in a specific scattering area is presented. Hence, the reflections of wave interacting with stiffeners can be analyzed to improve the diagnostic leading to a point by point interrogation (local approach). Theoretical aspects are investigated to correctly exploit the technique leading to a geometrical reduction to describe the propagation of the A0 mode including boundary (stringer) reflections. The model is capable to return the optimal design of the system achieving a high performance diagnostic. Several measurements are carried out to validate the adopted propagation model and a promising result in agreement with classic ultrasonic nondestructive testing is thus obtained and discussed. Furthermore it is shown that accounting Lamb wave reflections improves the localization accuracy respect a general purpose reconstruction algorithm while making use of fewer number of sensors possible or increase the probability of detection combining both methodologies. The mentioned results are achieved with large experimental campaigns as well as comprehensive numerical simulations with the aim to better understand the physics of wave propagation in composite media typically adopted in the aerospace field. Several strategies have been investigated using finite element methods with the attempt to reduce the experimental costs as well as system validation efforts. Using an effective equivalent single layer approach, the flexural behavior of the A0 mode has been modeled correctly. The proposed simulated environment allows to correctly relate the propagation and damage interaction behavior to effective features to detect damage with fewer efforts possible. Moreover, a preliminary and strategic analysis for the global approach is indeed carried out with the attempt to verify the feasibility of a numerical framework for system performance assessment using a (model assisted) probability of detection approach. The concluding part of the work focuses on a preliminary investigation of a transducer self-diagnostic procedure, aimed to in-situ monitoring of the sensors and actuators used in the SHM methodologies presented. Due to the large number of distributed PZTs needed to correctly nterrogate the structure, confirming if sensors/actuators are functioning properly during operation is a crucial process to minimize false alarms in the diagnosis. The procedure verified is based on the capacitive analysis of piezoelectric sensors, which is manifested in the imaginary part of the measured electrical admittance. Even though a further investigation is needed to study more complex sensor fault scenarios, the final algorithm is able to simultaneously sort sensors and detect damages with information gathered from healthy transducers