Abstract
Klassische Betondeckungsmessgeräte geraten bei Betondeckungen von mehr als 6 bis 7 cm und bei Objekten hinter oberflächennaher Bewehrung an ihre Grenzen. In diesem Beitrag wird für tiefere ...Objekte primär auf Ultraschall eingegangen und zunächst dessen Einsatzbereich von Radar abgegrenzt. Während die „Betondeckung“ mit max. 6 bis 7 cm nur für die Dauerhaftigkeit von Beton eine Rolle spielt, werden Radar und Ultraschallecho zur Ermittlung der „Einbautiefe“ von Hüllrohren und Bewehrung in deutlich größeren Tiefen verwendet, deren Kenntnis primär für den Nachweis der Standsicherheit von Konstruktionen notwendig ist (ZfPStatik). Dabei entscheiden Prüfaufgabe und Randbedingungen, welches Verfahren zum Einsatz kommt. Durch systematische Untersuchungen an Betonbauteilen und der Variation von Verlegedichte der Bewehrung an der Oberfläche, Einbautiefe, Stababstand der zu detektierenden Bewehrung und deren Durchmesser werden Leistungsfähigkeit und Grenzen von Ultraschall in Echo‐Anordnung (Sender und Empfänger eines Arrays auf einer Seite des Bauteils) hinsichtlich der Detektierbarkeit von Hüllrohren und Bewehrungsstäben aufgezeigt und die Genauigkeit der Messung der Einbautiefe ermittelt. Diese Erkenntnisse zu Ultraschall werden abschließend im Vergleich zur Leistungsfähigkeit von Radar und magnetisch induktiven Verfahren eingeordnet, die bereits in vorangegangenen Beiträgen behandelt wurden. Durch die zusammenfassende Betrachtung am Ende dieses Beitrags soll es dem Anwender erleichtert werden, das für seine Prüfaufgabe und Randbedingungen am besten geeignete Verfahren auszuwählen und realistische Erwartungen an die erzielbaren Ergebnisse zu stellen.
Abstract
Detection of tendon ducts and rebars and the accuracy of the measured concrete cover using ultrasonic echo
Classical covermeters come to their limits when the concrete cover exceeds 6 to 7 cm or beneath a mesh. Concrete cover measurement with these devices is performed up to 6 to 7 cm and is only of interest for durability. Concrete cover in greater depth is performed with Radar and Ultrasonic Echo with the focus on stability of structures (NDT‐SC,
s
tatic
c
alculations). The decision of the appropriate method depends on the boundary conditions, given by the spacing of the rebars near the surface, the depth, diameter and spacing of the objects to be detected. These parameters have been varied systematically in different concrete members to quantify the accuracy as well as strength and limitations especially for Ultrasonic Echo. The obtained results will be set in the context of Radar and magnetic methods with results of former publications. This will help the operator to make the best decision to find the appropriate method according to his testing task or boundary conditions.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This paper examines on the obstacles specific to the implementation of non-destructive testing (NDT) techniques in additive manufacturing (AM). The general challenges impeding the adoption of AM for ...volume production of parts, and the use of NDT techniques to ameliorate some of these challenges are studied. These challenges include the lack of understanding of AM materials, and insufficient standards for the mechanical testing and NDT of additively manufactured parts. An overview on the principle of operation for in-process inspection NDT methods is presented. The techniques include thermography, and acoustic emission testing. The applications of these NDT techniques in AM and their suitability for defects detection of additively manufactured parts are reviewed. The sensitivity, and the advantages and disadvantages of each technique are evaluated. The types of defects, and the detectability of these defects by NDT techniques are assessed.
Full text
Available for:
BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
This volume describes the fundamentals and techniques necessary for Lamb-wave-based damage identification. This damage assessment method offers efficient structural failure detection which lowers ...maintenance costs and increases safety benefits.
Full text
Available for:
FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Non-destructive testing (NDT) is an important mean to ensure the welding quality of nuclear island machinery. The domestic welding acceptance standards of nuclear power plants are from foreign ...classic codes including ASME and RCC-M. However, basis principles of formulating the acceptance criteria are unclear. Based on systematical comparison of NDT acceptance criteria in major standards, it is found that the NDT acceptance standards in ASME and RCC-M are similar since RCC-M referred the system and principles of ASME, although there are several variations in detail. But the two codes both differ greatly from other welding acceptance criteria such as PNAE G-7-010-89 and ISO 5817. These acceptance criteria are mainly based on engineering experience at the time. This leads to inconsistencies in the definition of so-called “weld class systems” which were primarily developed based on concepts related to good workmanship but have little or no relation to the actual performance of the welded structure. The difference in the design standard system also affects the formulation of the NDT acceptance criteria. With the development of fracture mechanics theory and wide application of computer technology, flaw assessment methods based on fracture mechanics were developed. In the in-service inspection process, flaw assessment methods were used to replace the traditional welding quality assessment standards, while the innovation during the manufacturing is not tried in nuclear industry yet. In order to apply the flaw assessment methods to determine the welding acceptance criteria for non-destructive testing of high temperature reactors, following principles should be considered. First, there is no need to formulate different acceptance standards according to non-destructive testing methods, and only the nature of the defect itself, such as type, location, size, and quantity, should be distinguished. Second, considering the consistency of standard in use, the acceptance criteria should also be consistent with the welding evaluation method of design code. Finally, from the perspectives of fracture mechanics and fatigue damage, the influence of welding defects on the mechanical properties could be analyzed and summarized to set up the relationship between the volumetric defects and service life. Combined with the characteristics of whether the equipment can be replaced and whether it is easy to monitor in service, one can determine the acceptance limits with different margins. The technical principles of the method are instructively important for determining an advanced, reasonable, and economic welding NDT acceptance criteria of advanced reactors.
Display omitted
•Critical review and monitoring progress of road transport infrastructure monitoring using GPR.•GPR-based intelligent data analysis using machine learning approaches.•To provide a ...supporting tool for decision making owners/operators.•Overcome the current challenges and constraints in road transport infrastructure monitoring.•Inner damages, road pavement structures (subsurface damages) and underground features assessment review.
Suitable road pavements assessment becomes essential to provide safe traffic movements of people and goods. Moreover, a reliable transportation network is a crucial aspect of economic growth. Road pavements are subjected to various factors that influence overall performance (e.g., traffic load, temperature, moisture, delamination of the pavement layers, subsurface condition, etc.). These factors can reduce the infrastructure's life and decrease the circulation comfort of the vehicles in the transportation network. Early inspection of pavements optimizes maintenance and repairing methodologies, decreasing the maintenance cost and increasing the lifespan of the road pavements. Non-destructive techniques are strongly recommended to achieve accurate and valuable information from the subsurface condition. Ground Penetrating Radar (GPR) is a non-destructive geophysical method widely used on infrastructure assessment, particularly in road pavements, due to its low operation cost, time-saving, non-invasive, and less workforce. This paper presents a critical state of the art of applying GPR to diagnose road pavement and detect inner damages such as debonding, sinkholes, moisture, etc. The incorporation of the GPR with other complementary techniques in pavement inspection is also discussed. Through the review, the GPR capabilities for road inspection and evaluation of subsurface identification have been successfully demonstrated and validated in numerous studies and case studies. Finally, the application of more recent processing techniques to support decision-making owners/operators, such as machine learning and intelligent data analysis methods, and the future challenges on the GPR application in road pavements are introduced.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Microwave imaging and defectoscopy are promising techniques for dielectric composite evaluation. Their most significant advantage is their relatively high penetration depth. Another feature worth ...noting is that traditional methods could not acquire an internal content with such a low impact on both the sample and surrounding environment, including the test operator, compared to other techniques. This paper presents microwave non-destructive and noninvasive methods for quality evaluation of layered composite materials using an open-ended waveguide probe. Pure |S11| parameters only exceptionally give a clear answer about the location of material cracks. Therefore, this makes it necessary to analyze these parameters simultaneously along with several other factors, such as stand-off distance, probe type or wave polarization. The purpose of the work was to find the dependency between the physical state of a layered composite powerplant pipeline and the S-matrix parameters response (reflection and transmission parameters) in a Ku frequency band that has not yet been extensively researched. Lower-frequency measurements broaden the application possibility for thicker composites, mainly because of a higher penetration depth and measurement setup availability. Different methods have been shown, including reflection and transmission/reflection methods, both in close proximity and in stand-off distance. The measurements are based on a low-complexity experimental setup.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This paper presents the conceptual design and prototype validation stages of the development of an in-line inspection tool that is based on circumferential guided waves generated by shear horizontal ...electromagnetic-acoustic transducers (EMATs). By combining the data from these sensors with information from accelerometers and an odometer, the tool can evaluate the integrity of the pipeline non-destructively and record the longitudinal and circumferential position of wall thinning areas and geometrical features or anomalies. This paper focuses on the identification of pipeline features, which is a key aspect in avoiding false-positive calls during real inspections. The performance of the tool in detecting and identifying such features in near-operational conditions in a defect-free qualification pipe loop is evaluated.
PDF
