Michele Carboni | Politecnico di Milano (original) (raw)

Papers by Michele Carboni

Materials Performance and Characterization, Sep 26, 2014

Springer eBooks, Dec 11, 2018

Chemical engineering transactions, Jul 20, 2013

Materials, Apr 24, 2024

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Nowadays, long welded railway rails are achieved by means of aluminothermic and flush-butt weldin... more Nowadays, long welded railway rails are achieved by means of aluminothermic and flush-butt welding processes. Compared to bolted joints, welds proved to be effective in terms of reduced wheel damage, ride comfort and maintenance. In rails, surface cracks often initiate within the welded and the heat affected regions of the foot, leading to brittle failure. On the subject, a recent work developed a probabilistic methodology for determining day-by-day failure probability. However, apart from this structural integrity study and few others, a complete damage tolerance approach should also consider the capability of non-destructive inspections. The latter is recognized as an essential input to define maintenance inspection intervals. The present work is focused on the capability assessment of Phased Array ultrasonic inspection applied to aluminothermicwelded joints by means of Probability of Detection curves, as a result of experimental and Model Assisted data samples.

42ND ANNUAL REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: Incorporating the 6th European-American Workshop on Reliability of NDE, 2016

Ultrasonics, Jul 1, 2015

The research investigates a Lamb-Wave based structural health monitoring approach matching an out... more The research investigates a Lamb-Wave based structural health monitoring approach matching an out-ofphase actuation of a pair of piezoceramic transducers at low frequency. The target is a typical quasiisotropic carbon fibre reinforced polymer aeronautical laminate subjected to artificial, via Teflon Patches, and natural, via suitable low velocity drop weight impact tests, delaminations. The performance and main influencing factors of such an approach are studied through a Design of Experiment statistical method, considering both Pulse Echo and Pitch Catch configurations of PZT sensors. Results show that some factors and their interactions can effectively influence the detection of a delamination-like damage.

e-Journal of Nondestructive Testing, 2023

The use of adhesively bonded joints has increased considerably due to their lightweight, relevant... more The use of adhesively bonded joints has increased considerably due to their lightweight, relevant strength-weight ratio and possibility to join multi-materials. Nevertheless, there are still some challenges in the application of this kind of joints in primary structures, such as guaranteeing their reliability during the components' useful life. Structural health monitoring methods are suggested to ensure in-service safety and reliability of adhesive joints. The acoustic emission appears promising because it can detect the elastic waves produced within the material when it is under damage or straining. This research focuses on mode I fatigue damage monitoring metallic double cantilever beam adhesively bonded joints using the acoustic emission method. Digital image correlation and visual evaluation were applied during fatigue interruptions to track the crack-tip position within the adhesive and correlate them with the acoustic emission outcomes. The acoustic emission method is susceptible and different kinds of waves (background, friction and damage) can be easily assessed during the tests, producing an immense amount of data. So, unsupervised artificial neural networks for patterning recognition were proposed. Self-organising maps and k-means algorithms were used for data clustering and then classified regarding their sources. Finally, the acoustic emission results, digital image correlation and visual evaluations were compared.

Considering railway axles, classical fatigue damage can occur at the body as a consequence of cor... more Considering railway axles, classical fatigue damage can occur at the body as a consequence of corrosion or ballast impacts, while fretting damage can occur as a result of micro-sliding between the wheel assembly and the press-fit seat. As safety critical components, railway axles, whose failure can lead to unacceptable human losses, are periodically inspected by means of well-established non-destructive techniques (typically ultrasonic and magnetic particle inspections) usually requiring expensive service interruptions. On the contrary, as shown within the aeronautical field, a condition-based maintenance can improve the safety and at the same time minimize costs respect to scheduled inspections. This paper investigates the feasibility of an Acoustic Emission based Structural Health Monitoring approach applied to railway axles subjected to classical and fretting fatigue damages. Experiments were performed on full-scale axles using a Vitry test rig, i.e. a three point bending test, with one acoustic-emission sensor coupled at the free end of the axle. Results are found to be consistent with damage evolution.

e-Journal of Nondestructive Testing

The application of Non-Destructive testing and Structural Health Monitoring systems in historical... more The application of Non-Destructive testing and Structural Health Monitoring systems in historical buildings is of great interest and actuality due to the need to guarantee safety and conservation. The present memory focuses on the case study of the historical wrought iron tie-rods of Duomo di Milano, Italy. In recent years, two of these elements presented critical failures, making necessary the replacement. Consequently, a monitoring methodology, based on acoustic emission, was defined. First, the fracture toughness of historical wrought iron was experimentally characterized by employing standard small scale specimens taken from one of the failed tie-rods. At the same time, acoustic emission was acquired to define a methodology for detecting and localizing the events due to damage in the material, separating those due to background noise by applying suitable pattern recognition algorithms. Subsequently, a tensile test was performed on a full scale section of the same tie-rod. Before...

Insight - Non-Destructive Testing and Condition Monitoring, 2020

Railway sleepers represent an essential element of the track; indeed, their structural integrity ... more Railway sleepers represent an essential element of the track; indeed, their structural integrity is closely related to important technical and safety issues. Today, periodical visual inspections are the only method applied to check the status of sleepers but are limited to visible surfaces, whereas the early detection of in-service cracks in the whole volume of sleepers would provide great advantages in terms of maintenance and management. The aim of the paper is to propose an acoustic emission (AE)-based structural health monitoring (SHM) approach that is able to detect the initiation and propagation of cracks in in-service pre-stressed concrete sleepers. The investigation is carried out in the laboratory, comparing the results obtained by acoustic emission monitoring and digital image correlation when subjecting pre-stressed concrete sleepers, taken from production, to both static and cyclic loads. The main points dealt with in the paper include the sensitivity of acoustic emissio...

Engineering Fracture Mechanics, 2014

Journal of ASTM International, 2005

ABSTRACT

Engineering Fracture Mechanics, 2007

The “plasticity-induced crack closure” phenomenon is the leading mechanism which controls the mai... more The “plasticity-induced crack closure” phenomenon is the leading mechanism which controls the main effects on fatigue crack growth (e.g. stress ratio and load interaction effects) in metallic materials. Experimental tests, consisting mainly in global and/or local compliance measurements of the considered specimen, are usually carried out to quantify the physical phenomenon, but some aspects concerning the elaboration of acquired local

Science and Technology of Welding and Joining, 2011

High power ultrasonic technology can currently count on a number of industrial applications. Ultr... more High power ultrasonic technology can currently count on a number of industrial applications. Ultrasonic welding, which is a standard joining technique in many applications on plastics, has few but well established metal applications, such as copper wires, pipes and connectors welding, or, considering spot welding of aluminium thin sheets, is attractive for the automotive industry field, where it could represent a possible cost effective alternative to resistance spot welding, clinching or self-pierce riveting. The present experimental study is addressed to this kind of application in order to evidence the effects of welding parameters and, most of all, their interactions on the tensile strength of tensile-shear spot welded lap joints. Relevant results have been achieved by dedicated and non-conventional instrumentations applied to the welder for measuring and controlling the process parameters. The best static performance has been taken as an input for the second part of the study regarding the fatigue behaviour and the joints failure modes.

Some typical fatigue failures of butt-welded rails consist in fractures ofthe web. In the early s... more Some typical fatigue failures of butt-welded rails consist in fractures ofthe web. In the early stage, crack propagates parallel to rail surface but, after a while,it tends to propagate with a slant surface. The aim of the present work is to analyse themechanisms involved in crack propagation in rail’s web in order to be able to predictthe crack path and, in a second step, the rail inspection intervals. From this point ofview, FEM analyses of an observed fracture were carried out in order to determinate K Iand KII history at different positions of crack tip during the passages of the typical loadsinduced by trains. The results have shown that the initial flaw tends to follow a pathwhere ∆KII is close to maximum values and a small superimposed KI traction is present.Fractographic analyses have confirmed that propagation is mainly controlled by modeII and that mode I is prevalent only after the final bifurcation of the cracks.