130,672 research outputs found
Adding Autonomy to Robotic Enabled Sensing
No full textThe capabilities of most non-destructive testing methods have been combined with some degree of automation in recent years, to enhance data acquisition speed, part coverage and inspection reliability. A plethora of automated or semi-automated inspection systems have been engineered to enable the robotic manipulation of specific types of sensors. Robotic inspection systems are usually operated through off-line programmed tool-paths. This approach works well when an accurate model of the part is available and the robotic inspection takes place in a well-structured environment, where the part position is precisely registered with respect to the robot reference system. However, it makes the inspection setup for each new part very time-consuming and dependent on the skills and experience of the robot programmer. Moreover, the real geometry of a part may significantly deviate from its digital counterpart, resulting in inaccurate tool paths. This work introduces a new approach capable of conferring full autonomy to robotic sensing applications, providing a breakthrough in the stateof-the-art. As a result of this work, fully autonomous single-pass geometric and volumetric inspection of complex parts, using one single robotized sensor, becomes possible. This concept can find wide applicability to the open problems of structural health monitoring of the modern age
Simulation of laser generated ultrasound with application to defect detection
No full textLaser generated ultrasound holds substantial promise for use as a tool for defect detection in remote inspection thanks to its ability to produce frequencies in the MHz range, enabling fine spatial resolution of defects. Despite the potential impact of laser generated ultrasound in many areas of science and industry, robust tools for studying the phenomenon are lacking and thus limit the design and optimization of non-destructive testing and evaluation techniques. The laser generated ultrasound propagation in complex structures is an intricate phenomenon and is extremely hard to analyze. Only simple geometries can be studied analytically. Numerical techniques found in the literature have proved to be limited in their applicability, by the frequencies in the MHz range and very short wavelengths. The objective of this research is to prove that by using an explicit integration rule together with diagonal element mass matrices, instead of the almost universally adopted implicit integration rule to integrate the equations of motion in a dynamic analysis, it is possible to efficiently and accurately solve ultrasound wave propagation problems with frequencies in the MHz range travelling in relatively large bodies. Presented results on NDE testing of rails demonstrate that the proposed FE technique can provide a valuable tool for studying the laser generated ultrasound propagation
Modello numerico per la simulazione e l’ottimizzazione di controlli non distruttivi con ultrasuoni
Get PDFI controlli non distruttivi basati sull’impiego di ultrasuoni sono ampiamente usati per la loro efficacia e affidabilità nel rilevamento di difetti. La generazione di onde ultrasonore e la propagazione in strutture di forma non regolare sono difficili da analizzare, soprattutto se la sorgente impiegata è un laser. Le tecniche numeriche per la simulazione del fenomeno reperibili in letteratura mostrano limiti di applicabilità per frequenze nel campo dei MHz e lunghezze d’onda molto corte. In questo lavoro presentiamo un metodo numerico in grado di risolvere accuratamente ed efficientemente problemi di generazione di onde ultrasonore tramite laser, con frequenze nel range dei MHz, e di propagazione in corpi relativamente estesi. La ricezione viene simulata con la propagazione degli ultrasuoni in aria, al fine di poter ottimizzare la configurazione completa per controlli non distruttivi con ultrasuoni senza contatto. Diverse configurazioni di ispezione sono state prima simulate tramite l’analisi numerica e poi riprodotte sperimentalmente per confrontare i risultati
A case study on the evaluation of friction stir welds by ultrasonic inspection technique
No full textFriction stir welding (FSW) is an innovative process that has been successfully used in joining aluminum alloys,
normally difficult to weld. Important advantages over fusion welding are better retention of baseline material
properties, lower residual stresses and excellent mechanical properties. Defects that occur in FSW joints are due
to improper tooling or setup. Non-destructive techniques used to inspect FSW joints are X-rays, eddy current,
conventional ultrasonic testing and dye penetrant proper only for surface breaking defects. Currently there is no
non-destructive technique that can guarantee absence of flaws in friction welds during manufacturing. In this
work, non-destructive remote testing of friction welds, based on laser ultrasonic technique, was investigated to
detect and quantify defects in the joint. The laser ultrasonic system generates ultrasonic acoustic waves by
thermal expansion and detects the surface vibration by an interferometric receiver. Several specific FSW samples
were inspected; some, manufactured with optimum parameters, used as calibration samples, and others,
manufactured with modified settings, with defects. The results of the tests conducted on the FSW samples show
that the system is able to detect the defect. A quantitative analysis of the defects was extrapolated from the
ultrasonic signals acquired across the weld. Since the defect evaluation can be done in-line, during the friction
weld manufacturing process, the laser ultrasonic technique plays an important role in containing the FSW
production cost
Detection, characterization and sizing of hydrogen induced cracking in pressure vessels using phased array ultrasonic data processing
Get PDFPressure vessels operating in sour service conditions in refinery environments can be subject to the risk of H2S cracking resulting from the hydrogen entering into the material. This risk, which is related to the specific working conditions and to the quality of the steel used, shall be properly managed in order to maintain the highest safety at a cost-effective level. Nowadays the typical management strategy is based on a risk based inspection (RBI) evaluation to define the inspection plan used in conjunction with a fitness for service (FFS) approach in defining if the vessel, although presenting dangerous defects such as cracks, can still be considered “fit for purpose” for a given time window based on specific fracture mechanics analysis. These vessels are periodically subject to non-destructive evaluation, typically ultrasonic testing. Phased Array (PA) ultrasonic is the latest technology more and more used for this type of application. This paper presents the design and development of an optimized Phased Array ultrasonic inspection technique for the detection and sizing of hydrogen induced cracking (HIC) type flaws used as reference for comparison. Materials used, containing natural operational defects, were inspected in “as-service” conditions. Samples have then been inspected by means of a “full matrix capture” (FMC) acquisition process followed by “total focusing method” (TFM) data post processing. FCM-TFM data have been further post-processed and then used to create a 3D geometrical reconstruction of the volume inspected. Results obtained show the significant improvement that FMC/TFM has over traditional PA inspection techniques both in terms of sensitivity and resolution for this specific type of defect. Moreover, since the FMC allows for the complete time domain signal to be captured from every element of a linear array probe, the full set of data is available for post-processing. Finally, the possibility to reconstruct the geometry of the component from the scans, including the defects present in its volume, represents the ideal solution for a reliable data transferring process to the engineering function for the subsequent FFS analysi
Metodologia non distruttiva per valutare la dispersione delle nanoparticelle in un nanocomposito – Recenti perfezionamenti
Get PDFUna tecnica di valutazione non distruttiva (NDE) in grado di testare la dispersione di nanoparticelle in un nanocomposito sarebbe di grande utilità per l’industria manifatturiera nella verifica della qualità dei prodotti realizzati e per garantire la conformità alle loro specifiche. Allo stato attuale risultano pochissime le tecniche di NDE in letteratura in grado di valutare il livello di dispersione delle nanoparticelle nell’intero nanocomposito. La tecnica di valutazione non distruttiva (NDE) presentata nel 2022 per testare la dispersione di nanoparticelle in un nanocomposito è stata oggetto di alcuni miglioramenti che hanno consentito di ridurre la dimensione minima degli aggregati di nanoparticelle rilevabili. La tecnica NDE si basa sulla termografia pulsata con analisi in fase (PPT) in modalità di trasmissione. La tecnica proposta è stata utilizzata per la valutazione del grado di dispersione di nanotubi di carbonio e di particelle di argento in un nanocomposito a base polimerica a bassissima concentrazione di nanofiller (inferiore allo 0,05% in peso), prodotto con un’innovativa tecnica di manifattura. I fasogrammi ottenuti con la tecnica presentata hanno mostrato chiaramente gli aggregati di nanoparticelle. Pertanto, il nuovo approccio NDE può essere applicato per verificare che i livelli di dispersione attesi siano rispettati nel processo produttivo.
Bibliografia:
1. Montinaro N., Fustaino M., Bellisario D., Santo L., Quadrini F., Pantano A. “Testing the Dispersion of Nanoparticles in a Nanocomposite with an Ultra-Low Fill Content Using a Novel Non-Destructive Evaluation Technique”, Materials, 15(3), 1208, 2022. DOI: 10.3390/ma15031208, ISSN: 19961944.
2. Bellisario D., Quadrini F., Santo L., Montinaro N., Fustaino M., Pantano A.. “Hybrid nanocomposites with ultra-low filling content by nano-coating fragmentation”, Polymer-Plastics Technology and Materials, 61(1), pp. 41–55, 2022. DOI: 10.1080/25740881.2021.1948060, ISSN: 25740881.
3. Montinaro N., Fustaino M., Pantano A.. “Carbon nanotubes dispersion assessment in nanocomposites by means of a pulsed thermographic approach”, Materials, 13 (24), art. no. 5649, pp. 1-13, 2020. DOI: 10.3390/ma13245649, ISSN: 19961944.
4. Pantano A., Montinaro N., Cerniglia D., Micciulla F., Bistarelli S., Cataldo A., Bellucci S., “Novel non-destructive evaluation technique for the detection of poor dispersion of carbon nanotubes in nanocomposites”. Composites Part B: Engineering, Vol. 163, p. 52-58, 2019. DOI: 10.1016/j.compositesb.2018.10.097, ISSN: 1359-8368.
Funding:
MUR, PNRR-M4C2, ECS_00000022
Aknowledgement:
Progetto: "SiciliAn MicronanOTecH Research And Innovation CEnter "SAMOTHRACE" (MUR, PNRR-M4C2, ECS_00000022), spoke 3 - Università degli Studi di Palermo "S2-COMMs - Micro and Nanotechnologies for Smart & Sustainable Communities
Simulation of laser-generated ultrasonic wave propagation in solid media and air with application to NDE
No full textUltrasonic methods are well known as powerful and reliable tool for defect detection. In the last decades focus and interest have been directed to non-contact sensors and methods, showing many advantages over contact techniques where inspection depends on contact conditions (pressure, coupling medium, contact area). The non-contact hybrid ultrasonic method described here is of interest for many applications, requiring periodic in service inspection or after manufacturing. Despite the potential impact of laser-generated ultrasound in many areas of industry, robust tools for studying the phenomenon are lacking and thus limit the design and optimization of non-destructive testing and evaluation techniques. Here a specific numerical method is presented to efficiently and accurately solve ultrasound wave propagation problems with frequencies in the MHz range traveling in relatively large bodies and through air. This work improves a previous numerical model where propagation of the acoustic waves through air had not been considered, allowing to simulate the presence of a non-contact transducer in reception in order to simulate numerically the complete experimental setup. It is very important to limit the amount of air to be considered in the FE analyses; otherwise the computational cost would often exceed the resources available. A way to solve the problem is to implement non-reflecting boundary conditions. A non-reflecting boundary condition allows all outgoing waves to exit the domain at the boundary where they have been imposed without reflection, thus it is possible to model only the portion of air between the non-contact transducer and the solid under testing. Several numerical and experimental analyses were conducted on a 136 lb AREMA rail, here we study in detail two fully non contact testing configurations for the rail head and web. The information that can be acquired is very valuable for choosing the right setup and configuration when performing non-contact hybrid ultrasonic inspection
Development of a methodology for the detection of vertical split head defects in the rail
No full textSimulazione di propagazione di onde ultrasonore con applicazione ai controlli non distruttivi
No full textI metodi di controllo ad ultrasuoni sono noti per essere efficaci ed affidabili per il rilevamento di difetti. L'uso del laser nei sistemi di controllo ad ultrasuoni consente l'ispezione remota, realizzabile in dinamico e automatizzabile. Inoltre, poiché le onde acustiche generate con il laser sono nel campo dei MHz, si ha una buona risoluzione spaziale per il rilievo di difetti. La propagazione di onde ultrasonore generate tramite laser in strutture di forma non regolare è un fenomeno difficile da analizzare. Le tecniche numeriche reperibili in letteratura mostrano limiti di applicabilità per frequenze nel campo dei MHz e lunghezze d’onda molto corte. In questo lavoro presentiamo un metodo numerico in grado di risolvere accuratamente ed efficientemente problemi di propagazione di onde ultrasonore con frequenze nel campo dei MHz che viaggiano in corpi relativamente grandi. Diversi test sono stati simulati tramite l'analisi numerica e poi riprodotti sperimentalmente per confrontare i risultati
Evaluation of Vertical Fatigue Cracks by Means of Flying Laser Thermography
No full textThe present paper proposes a new procedure to analyze the temperature field distribution during Flying Laser Spot and Laser Line Thermographic scanning (FLST, FLLT) of metallic components, in order to detect vertical surface cracks. The methodology exploits the changes in the temperature field produced by a vertical crack, acting as a barrier towards heat diffusion, when the laser approaches the defect. A number of small regions of interests (ROIs) is placed nearby and around the laser source. The average temperature from each ROI is then monitored during the laser scanning. Vertical cracks can be detected by analyzing and comparing the temperature fluctuations from each ROI when the laser crosses a crack. The paper, in particular, illustrates how the use of multiple ROIs, placed at different locations, may provide additional information that can be used to characterize the defect, and to identify the crack tip location. The approach is validated on plates made of steel and aluminum alloy, where natural cracks have been introduced by fatigue loading, and whose surface has been painted to enhance emissivity. Scratches in the paint have been artificially made in order to analyze their influence on the defect signature. The proposed experimental setup is further simplified by moving the plate samples, mounted on slits, in front of a still laser source and camera head
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