Rolling contact fatigue is caused by interaction of train wheels with railheads. To minimize operational risks railways infrastructure owners can ask for regular inspections to determine critical sections of assets in a predictive maintenance scheme.
Some defect types, for instance (sub-)surface anomalies like squats, were herein assessed with our train UST02 by specific ultrasonic (UT) and eddy current (ET) testing probes, but each with inherent limitations. Additionally surface imaging video (VT) was recorded.
Machine learning techniques were applied to combine data from these three inspection systems from a recorded track, which had a squat defect population. The target was to provide optimized classification as basis for prediction of rolling contact fatigue growth.
We describe results of this ‘combined systems method’, CSM, with classification features derived from densely spaced clusters with input from UT B-scans, and parameters from ET and VT raw data after signal and image processing, respectively. In comparison to classification per single system, CSM gave significantly improved hit rate without degradation of specificity.
NDE of aerospace composites with Dantec Dynamics’ Laser Shearography
Author: G.-S. Crabus
Company: Dantec Dynamics GmbH
Kaessbohrerstr. 18, 89077, Ulm, Germany
Relevance of the work:
– NDE of composites
– Technologies and Instrumentation
Laser Shearography, an optical based Non-Destructive Testing (NDT) technique identifies internal material discontinuities or anomalies in components within seconds. The sensor measures microscopic surface deformations caused by internal flaws when a small stress is applied to the object. This can be done using thermal, pressure, vibration or mechanical excitation. The results are readily available during the non-destructive measurement itself.
Dantec Dynamics’ Laser Shearography are portable, compact and robust inspection systems that efficiently finds flaws where other NDT methods don’t. Two inspection philosophies are available: [versatile excitations and object dimensions] or [fast inspection and fix setup]. The FlawExplorer has the ability to inspect areas up to 2 m² (20 ft²) in one heat/ vacuum / vibration shot within a minute whereas the Hood Q-810 system can provide a vacuum-excited A4 inspected area within 20 seconds.
In the aerospace industry, manufacturing plants but also service companies are confronted to challenging composite failures on a daily basis. Laser Shearography provides a reliable solution for the detection of flaws like: Delaminations, Disbonds, Cracks, Crushed core, Kissing bonds, Impact damage (BVID’s), Wrinkles, Fluid ingress, Cracked cores, Repair defects, Voids, Foreign Objects, etc.
This presentation will highlight the technology itself, but also its actual and potential contribution to the enhancement of the NDE in the aerospace industry.
Impacts on airplanes fuselage can be caused by hail storms, falling tools, bird impacts, and various other sources. The position, size, diameter, shape, and correlation between defects must be verified to determine the airplane serviceability as fast as possible to minimize downtime and its associated cost. The geometrical assessment of dents is one of the critical tasks performed by MROs, therefore demanding repeatable, traceable and accurate measurement tools. This paper describes how a metrology-grade 3D scanning technology combined with a dedicated software can simplify the deployment in the field, increase the ease-of-use by the inspectors, and allow quick decision making while addressing the needs for high quality auditable results. Inspectors can configure their scan and reporting parameters to meet their specific needs and export the data in Excel, cvs and txt file formats. This solution now certified by Airbus and included in their Technical Equipment Manual can contribute in reducing damage assessment time by up to 80% while minimizing the risk of human error.
An industrial videoscope is an instrument that enables inspectors to visually inspect areas that are otherwise difficult to access, such as the combustion chamber of a jet engine. Videoscopes support industry by helping reduce time, labor, and associated costs by enabling users to nondestructively inspect inside components would otherwise need to be disassembled. To meet the requirements of industry, Olympus has developed a brighter illumination system for videoscopes. This paper discusses this new illumination system and the positive impact it has on image quality.
The work was aimed at the study of fatigue cracks growth process in dual (γ + ε) Fe-20% Mn metastable steel belonging to the class of TRIP-steels by non-destructive evaluation methods. Previously it was shown that plastic deformation induced γ→ε→α’ martensitic transformation in these steels have been developing during mechanical loading. Fracture mechanics cyclic tests of compact tension (CT) V-notched specimens with thickness of 2.6 mm were performed at room temperature using resonant testing machine. Monitoring of fatigue crack was carried out directly in the process of cyclic loading by non-destructive evaluation methods such as magnetic Barkhausen noise measurement, dynamic speckle interferometry and thermal imaging. The use of these methods was based on the evaluation of changes in physical properties of metastable Fe-20% Mn steel related to the formation of ferromagnetic α’-martensite in the local plastic zone ahead of crack, as well as on evolution of the of cyclically deformed specimens surface. As informative parameters when measuring the magnetic Barkhausen noise RMS voltage and the coercive force Hc were selected. Revealed significant changes in RMS and Hc magnetic parameters measured along the direction of growing fatigue crack are associated with the formation of α’-martensite in plastic zone. The usage of thermal imager makes it possible to observe markedly changes of temperature field on the specimens surface with fatigue crack growth after reaching 3.3×105 of loading cycles at the appropriate range of the stress intensity factor ΔK = 33 МРа×m1/2. Possibilities of fatigue crack monitoring under cyclic loading by non-destructive evaluation methods and establishing the relationship between stages of crack growth and the detected changes of Fe-20% Mn metastable steel physical properties in the local area of plastic deformation ahead of crack are highlighted.
In China, Level 1 maintenance of CRH is one of the most important parts of railway transportation. Its quality is directly related to the safety of passenger’s life and property and enterprise economic benefit. CRH Level 1 maintenance is including the inspection of wheel set, pantograph, key running gears such as brake part and etc., key parts on the roof such as Porcelain insulator. Research on how to effectively combine image processing and NDT technology in Level 1 maintenance system, not only can improve the repair quality but also can improve inspection efficiency, to ensure the CRH safety. In this paper first outline the development and application of image processing and NDT technology in high speed inspection system at home and abroad. Then detailed introduces composition, layout, function and technical principle of Level 1 maintenance system in China. At last, introduces the system data comprehensive analysis platform, and points out the effective application of database management technology to carry out multi-dimensional management of CRH can improve and strengthen the quality and efficiency of CRH repair work.
Welded structures based on thick metal sheets are usually produced by conventional welding technologies but to an increasing degree also by laser multi-pass narrow gap welding. With the latter technique metallic components with a large wall thickness of up to 100 mm can be efficiently welded. Due to economic reasons a conventional NDT approach based on ultrasonic testing of completely welded components after the welding process is inefficient. If structurally relevant defects are found, a repair is no longer possible and the whole component has to be rejected. For a better identification of defects during the welding process, a temperature-resistant inline monitoring approach is necessary but not yet available. In the present article we describe a multi-method approach based on three different techniques: Phased Array Ultrasonic Testing, Acoustic Emission Testing and Laser Speckle Photometry. We present intermediate results of inline measurements and comparisons with conventional NDT using ultrasonic immersion testing.
Laser Speckle Photometry (LSP) is an innovative non-destructive monitoring technique based on the detection and analysis of thermally or mechanically activated characteristic speckle dynamics in the non-stationary optical field. With the development of speckle theories, it is found that speckle pattern contain information of the object’s surface.
Concrete material parameters such as the porosity are obtained by LSP based on the evaluation of the temperature line. The implementation of this evaluation concept for control of additive processes shows a great potential. Moreover, the defects such as pores and microcracks occurring during the laser-melting process is possible to detect immediately after their formation by appropriate countermeasures. So the defects can be eliminated by re-melting of the affected area. As result time and cost of intensive material testing and rework will be significantly reduced. The designed sensor system supports the minimization of the dropout rate of process conclusively so that reduces energy, material and inert gas consumption significantly. LSP sensor is integrated directly in the manufactured machine. The communication between the two processes is realized depending on the development of the electronics and algorithms for a regulative approach.
First investigation for LSP test was carried out on Selective Laser Melting (SLM) and Micro-Laser Cladding (LMC) test specimens. The paper shows that the defects and inhomogeneities in the samples that were produced by reduced and greatly increased input energies are detectable by using LSP technique. At the same time, based on the calculation of the thermal diffusivity of the optical speckle temperature, the so-called speckle diffusivity decreases with increasing porosity of the samples. This LSP-Parameter was used for the detection of the mixing degree of contact with the substrate by LMC manufacturing. The accuracy of the results by the measuring speed of 100 contacts per minute is 6.7% verified by X-ray spectroscopy.
The nuclear industry worldwide needs efficient and innovative ways to carry out non-destructive testing in underwater situations. In particular, nuclear power plants expect a variety of complex underwater inspection activities to be performed during an outage. ROVs such as the Visatec Dolphin, need to inspect both primary and secondary side components as well as RPV internals. Specialist ROV technology allows inspections to happen in situations that are hard to reach with any other inspection method. The newest generation of ROVs can perform sophisticated visual inspections and can incorporate a gripping device that can retrieve fallen debris. Inspections can be carried out for reactor coolant system components, pressure vessels, tanks and piping in nuclear power plants worldwide. The vehicles can be calibrated under water at any time during the inspection process to avoid any interruption to the testing work. These ROVs carry out visual testing (with ultrasonic testing as an option) and can evaluate the status of nuclear reactor internals. In short, this equipment is critical in confirming the safety of components for a nuclear plant’s long-term operation and safety. This paper cites numerous case studies of how our multi-function underwater submarine ROV, the Visatec Dolphin with an integrated gripper arm, has carried out complex inspections in a nuclear application. It also discusses specific problems involved in nuclear reactor underwater testing and presents solutions using the latest ROV underwater technology.