Search results for "Non-destructive test"
showing 10 items of 29 documents
Influence of Welding Time on Tensile-Shear Strength of Linear Friction Welded Birch (Betula pendula L.) Wood
2015
Linear friction welding of wood is a bonding process applied to wood and during which a stiff bond line is formed by the softening and rehardening of wood components to form a composite material composed mainly of wood fibres embedded in a modified lignin matrix. Unfortunately, the bonds tend to spontaneously delaminate or lose their strength when exposed to moist conditions. Some approaches were previously applied to overcome this problem, but so far a suitable solution has not been found. This paper presents results of applying post-welding thermal modification to reduce the moisture sensitivity of welded wood. The experiments included welding of birch wood, thermal modification under sup…
Non-destructive determination of ‘Big Bang’ nectarine quality and harvest maturity
2021
In nectarines, potential shelf life and quality at consumption are closely related to the ripeness stage of fruit at harvest. Usually, the harvest is based on color, firmness, sugar and acids content of fruit, although these determinations are carried out through destructive methods and in a limited number of samples. The technique of Vis/Nir spectroscopy is used for the development of a non-destructive index based on the difference of absorbance (IDA) between two wavelengths near the absorption peak of chlorophyll-a, and it allows monitoring of changes in ripeness processes directly in the field. The objective of this paper is to track changes in quality that occur during nectarine ripenes…
Flying laser spot thermography for the inspection of aerospace grade Fibre Metal Laminates
2017
This work analyses a Non Destructive Testing approach for the detection of interlayer disbonds in aerospace grade Fibre Metal Laminates (FMLs). The NDT setup consists of a continuous laser, focused and moved over the material surface, while an IR thermal camera acquires its thermal footprint. A numerical model of the NDT setup is presented, where the material thermal response is analysed to evaluate the features of the defects signatures. In particular, the response from various types of FMLs is evaluated.
Fine Alignment of Thermographic Images for Robotic Inspection of Parts with Complex Geometries
2022
Increasing the efficiency of the quality control phase in industrial production lines through automation is a rapidly growing trend. In non-destructive testing, active thermography techniques are known for their suitability to allow rapid non-contact and full-field inspections. The robotic manipulation of the thermographic instrumentation enables the possibility of performing inspections of large components with complex geometries by collecting multiple thermographic images from optimal positions. The robotisation of the thermographic inspection is highly desirable to improve assessment speed and repeatability without compromising inspection accuracy. Although integrating a robotic setup fo…
Ultrasonic inspection for the detection of debonding in CFRP-reinforced concrete
2017
Fibre-reinforced plastic (FRP) composites are extensively used to retrofit civil structures. However, the quality and the characteristics of the bond between the FRP and the structure are critical to ensure the efficacy of the retrofit. For this reason, effective non-destructive evaluation (NDE) methods are often necessary to assess the bonding conditions. This article presents an ultrasonic technique for detecting defects at the FRP-substrate interface. The technique uses the Akaike Information Criterion, to detect automatically the onset of the ultrasonic signals, and the novel Equivalent Time Lenght (ETL) parameter, to quantify the energy of the propagating ultrasonic signals along the i…
Laser ultrasonics for defect evaluation on coated railway axles
2020
Abstract This scientific paper focuses on the application of an advanced non-destructive technique for an effective inspection of railway axles. The method pertains to ultrasonic techniques, which are widely used in the railway field. The experimental investigation was carried out on simulated defects tooled near the cross section reduction of the axle, in order to simulate fatigue cracks which, due to notch effect, can trigger crack propagation and axle failure. The aim of this research activity is to evaluate how efficiently the proposed technique detects defects and to verify its applicability to axles with a black coating for protection. In view of the experimental setup, comprising a p…
In-process calibration of a non-destructive testing system used for in-process inspection of multi-pass welding
2020
Abstract In multi-pass welding, there is increasing motivation to move towards in-process defect detection to enable real-time repair; thus avoiding deposition of more layers over a defective weld pass. All defect detection techniques require a consistent and repeatable approach to calibration to ensure that measured defect sizing is accurate. Conventional approaches to calibration employ fixed test blocks with known defect sizes, however, this methodology can lead to incorrect sizing when considering complex geometries, materials with challenging microstructure, and the significant thermal gradients present in materials during the inter-pass inspection period. To circumvent these challenge…
A numerical and experimental study through laser thermography for defect detection on metal additive manufactured parts
2017
Additive manufacturing has been recently employed in industrial sectors with the fundamental requirement for zero defect parts. Technological developments in additive manufacturing notwithstanding, there continues to be a scarcity of non-destructive inspection techniques to be exploited during the manufacturing process itself, thus limiting industrial advancements and extensive applications. Therefore, being able to integrate the defect inspection phase within the additive manufacturing process would open the way to enabling corrective actions on the component in itinere, that is, before reaching the final product. For this reason, new methods of in-process monitoring are gaining more and m…
Detection and characterisation of disbonds on Fibre Metal Laminate hybrid composites by flying laser spot thermography
2017
Abstract In this work a novel data collection and processing is proposed for the Infrared Non-Destructive Testing (IR-NDT) of interlaminar disbonds on Fibre Metal Laminate (FML) hybrid composites. The adopted active IR-NDT scheme uses a pointwise laser heat source that is moved along a raster scanning trajectory over the object surface. A Focal Plane Array IR camera is employed to acquire the thermal field generated by the moving heat source. Disbonds defect signatures are then searched by analysing the perturbations of the temperature distribution over a reference area following the heat source. The proposed methodology has been implemented on a GLARE sample, since this class of FMLs has g…
A Numerical Study on Interlaminar Defects Characterization in Fibre Metal Laminates with Flying Laser Spot Thermography
2018
This work describes a numerical study on non-destructive evaluation of interlayer disbond defects in aerospace grade Fibre Metal Laminate sheets (FMLs). A recently proposed infrared non-destructive testing setup is considered, where a continuous laser is moved over the material surface, while the thermal footprint of the moving heat source is acquired, e.g. by an infrared thermal camera. Interlayer disbonds are then detected by analysing the features of the acquired thermograms. The experimental feasibility of this approach has been recently proved. The present work proposes a numerical simulation of the NDT approach, where the material thermal response is analysed and correlated to defects…