Buckling Load Prediction of Oblate Ellipsoidal Shells Using Force Stiffness Technique

Width effect on the modulus of elasticity of hardwood lumber measured by non-destructive evaluation techniques

The Westinghouse Science and Technology Center has undertaken a program to develop nondestructive evaluation (NDE) techniques for characterizing the internal structure of SiC particle-reinforced aluminum matrix composites at critical stages during fabrication [1–5]. Because of the large number of processing variables in the manufacture of metal matrix composites (MMC), the likelihood of having detrimental discontinuities is high. The detection of potential defects early in the processing cycle would increase the overall system yield, lower costs, and enhance final product quality [4]. The aim of this investigation was to develop and conduct NDE at various stages of MMC fabrication, correlate the results with microstructural characterization, and establish qualified product quality assurance processes. A large-scale billet was fabricated specially using powder metallurgy techniques to facilitate this objective. The billet contained implanted silicon-carbide particle and aluminum powder clusters as inspection targets. The billet was subsequently extruded into a primary cylindrical extrusion, and finally into a flat plate. The NDE objectives included evaluating the detectability and mapping the implanted defects through each of the processing steps. Comprehensive evaluation of MMC structures requires the use of multiple NDE techniques, including ultrasonic, eddy current, and radiographic testing. This paper concentrates on the results of the ultrasonic investigations. Our experimental approach was: (1) fabricate a MMC billet with intentionally placed inhomogeneities; (2) develop and implement NDE techniques to characterize the MMC internal structure; (3) extend the NDE techniques to intermediate processing and final product forms; and (4) correlate the NDE data with microstructural characterization and mechanical testing results.

Nondestructive evaluation (NDE) techniques are used in many industries to evaluate the properties of components and inspect for flaws and anomalies in structures without altering the part’s integrity or causing damage to the component being tested. This includes monitoring materials’ condition (Material State Awareness (MSA)) and health of structures (Structural Health Monitoring (SHM)). NDE techniques are highly valuable tools to help prevent potential losses and hazards arising from the failure of a component while saving time and cost by not compromising its future usage. On the other hand, Artificial Intelligence (AI) and Machine Learning (ML) techniques are useful tools which can help automating data collection and analyses, providing new insights, and potentially improving detection performance in a quick and low effort manner with great cost savings. This paper presents a survey on state of the art AI-ML techniques for NDE and the application of related smart technologies including Machine Vision (MV) and Digital Twins in NDE.

Compared with conventional non-destructive evaluation (NDE) techniques, such as radiography, ultrasound, magnetic particle inspection and eddy current, the coplanar capacitive sensing technique is a newly emerging technique with promising future prospects. Aiming to show the capabilities of coplanar capacitive sensors (CCSs) for NDE, this review paper exploits existing literature on the subject to provide a general systematic overview of the capacitive NDE technique using CCSs. This review focuses on the fundamentals of the technique, factors affecting sensor performance, existing designs of CCSs used for defect detection and finally, the different applications of CCSs for defect detection in different fields of NDE. The existing challenges and future prospects of the CCS technique are also discussed. Amidst the prevalent challenges, obtaining better performance from CCSs has been mostly done by using different geometric designs, but less emphasis has been put on optimising circuit design and choice of sensor component materials. The key to optimisation of sensor performance is rooted in establishing a balance among trade-offs. The various advantages of the technique, compared to conventional NDE techniques, allow for different applications and attest to the potential of the technique for new applications in the future.

: NDE methods evaluated included eddy current measurements, ultrasonics, radiography, acoustic emission monitoring, acoustic-ultrasonics, and interferometric (e.g., shearography) methods. The major interest was in the detection of damage to COPVs caused by impacts at energy levels that would leave no visible scar on the COPV surface. Each of the above-mentioned NDE methods was assessed with regards to its utility for the detection of impact damage to COPVs and its applicability in the field. Three COPVs were impacted at various energies and then inspected using each of the NDE methods. The results for each method are presented, followed by a summary comparing the advantages and disadvantages. Several NDE techniques were shown to be effective for detecting impact damage sites on graphite/epoxy overwrapped pressure vessels even if the impact energy was below the threshold for creating visible surface damage. These techniques (ultrasound, radiography, thermography, shearography, and eddy current testing) are sensitive because a small dent is left in the liner following the impact. The impact damage detection thresholds for the various NDE techniques employed depend on the size and shape of the vessel. The tup characteristics and the internal pressure of the vessel during impact also affect the degree of damage and, hence, the detectability of the impact site. The size of the indication associated with a flaw is also dependent on the technique used. Visual inspection can lead to an underestimate or lack of detection of the damage. For both thermography and shearography, consistent sizing could be accomplished through the use of calibration standards and a consistent test set-up. The ultrasonic and eddy current results are most likely accurate measures of how much of the liner was debonded.

Non-destructive evaluation (NDE) techniques are essential to detect damage in structures, including airplanes, and require further improvement. Extant NDE techniques are often time-consuming, and their spatial resolution and in situ capabilities are limited. In this paper, a new NDE technique is demonstrated using the Joule heating effect of carbon nanotube (CNT) networks embedded within structural composites (also known as nanoengineered composites). Via local resistive heating, damage in the composite causes increased electrical and thermal resistance that is visualized with standard thermographic imaging. Multiple improved characteristics have been experimentally confirmed, including real-time measurement, high resolution (~0.1 mm), and simple and low-power (15 o C rise at 1 W) operation. Furthermore, the ability to detect barely visible (and internal) damage, and an additional de-icing functionality, are presented. This materials-based sensing technique offers a novel and practical approach for in situ structural health monitoring to prevent structural failures.

Evaluation of Fuel-Clad Chemical Interaction in PFBR MOX test fuel pins

Ultrasonic NDE techniques for the evaluation of matrix cracking in composite laminates

Evaluation of the mechanical properties of Douglas-fir and Japanese cedar lumber and its structural glulam by nondestructive techniques

Non-destructive evaluation techniques that are based on electromagnetic methods are commonly used for inspection of metallic and carbon fibre reinforced plastics parts. Some of these inspection methods are based on eddycurrents which are generated by the electromagnetic induction phenomenon occurring under variable magnetic induction field. In eddy-currents testing, the depth of penetration into the material is controlled by the conductivity of the tested material and also the work frequency. Transient eddy-currents, also called pulsed eddy-currents, is an emerging non destructive technique that employs a pulsed excitation to induce a transient electromagnetic response from defects lying deep within a conducting structure. Such defects are difficult to inspect by conventional techniques, such as harmonic eddy-currents or ultrasonics. A large number of recent scientific publications have dealt with the theoretical understanding of the pulsed eddy-currents phenomenon and have also undertaken the design feature of appropriate probes. Finite element solution of the governing equations has been used to simulate the output signals as function of the input electrical excitation signal. Considering a B-scan strategy, simulation of a pulsed eddy-currents based probe is performed in this work with the objective to assess detectability of small defects through monitoring impedance changes of a detection probe.

Nondestructive evaluation techniques are mainly used for two purposes. One of these tasks is quality control in the production process. The second task is concerned with the problem of aging constructions and material degradation to ensure the safe operation of industrial installations. In both cases NDE provides a snapshot of the actual system situation. Dynamic effects are almost neglected. But for system monitoring and process control it is necessary to investigate the dynamics of the system. The paper deals with special statistical reconstruction techniques that are capable to record the dynamic behavior of systems based on nondestructive evaluation techniques.

Key stages of adhesively bonded repairs

Polymer coatings provide an excellent corrosion barrier for Al-skinned military aircraft. However, the degradation and damage of the coatings in their service life over time leads to the initiation of corrosion damage at the substrate level. Early detection and negation of such activity can provide extensive cost savings. Several Electrochemical techniques and Non Destructive Evaluation (NDE) show promise in detecting the onset of corrosion under such coatings. Current accelerated testing of aircraft coating systems for corrosion protection relies heavily on salt spray methods. Electrochemical techniques such as Electrochemical Impedance Spectroscopy (EIS) and Electrochemical Noise Methods (ENM) provide insight into the global properties of a coating system, and both techniques are being used on a limited basis. However, there is a need to investigate corrosion events with greater spatial resolution under coatings at the metal/coating interface. Such corrosion activity may be related to coating defects and variations in the surface chemistry of the underlying metal. The Scanning Vibrating Electrode Technique (SVET) has been developed to allow the investigation of localized corrosion activity with high spatial resolution. Such activity may be associated with coating defects or galvanic coupled regions of the metal surface. Electrochemical and NDE techniques were used to investigate the early stage of corrosion activity under protective coatings. Coatings in this investigation ranged from a simple epoxy amine to commercially used military aircraft polyurethane coatings. SVET testing of panels with intact high-resistance barrier coatings could not reveal corrosion damage under normal testing conditions because of little or no corrosion activity within the limited exposure time. Chemical, mechanical, and electrochemical means of accelerating the corrosion damage were utilized to obtain results in a reasonable time frame. Corrosion initiation and its progress under the coating were studied in detail and the results are discussed here. Complimentary high-resolution NDE techniques, such as Scanning Acoustic Microscopy (SAM) and Fan Thermography measurements were used to identify the corrosion sites. The overall objective of this investigation is to establish a correlation between the electrochemical and NDE techniques.

Cavitation was examined in an Al–Mg solid-solution alloy deformed in tension at 400 °C under conditions providing solute-drag creep, which can produce tensile ductilities from 100% to over 300%. Two nondestructive evaluation techniques were employed to measure the extent of cavitation: ultra-high-resolution x-ray computed tomography and pulse-echo ultrasonic evaluation. Subsequent to nondestructive evaluation, the sample was sectioned for examination by standard metallographic techniques. Metallographic examination confirmed that both nondestructive techniques accurately indicated the extent of cavitation. Ultrasonic testing provided a practical means of distinguishing material with cavities from that without cavities. Ultrahigh- resolution x-ray computed tomography provided an accurate three-dimensional image of internal cavitation.

Nondestructive evaluation of grout defects in internal tendons of post-tensioned girders