Nondestructive Testing Research Articles

Magnetization mechanisms for non-destructive evaluation of low-carbon steels subject to early-stage low-temperature thermal oxidation

In this work, an investigation is done to identify the magnetic non-destructive testing techniques and their related magnetization mechanisms and, eventually, the associated indicators that present the most distinguishable response to changes in steel properties due to the onset and evolution of starting corrosion by thermal oxidation at low temperatures. This is found by measuring magnetic responses of Magnetic Hysteresis Cycle (MHC), Magnetic Barkhausen Noise (MBN), and Magnetic Incremental Permeability (MIP) at the early stage of corrosion. Herein, the magnetization mechanism identified by the Domain Wall Bulging (DWB) effect and represented by the indicator Δ|Z|MIP from the MIP response is ranked the most sensitive indicator by Pearson’s linear correlation coefficient (LCC). It is immediately followed by the Domain Wall’s Irreversible Motions (DWIM) represented by the MBN coercivity indicator. Both mechanisms are associated with the structure and kinetic of the magnetic domains, respectively, under low and medium magnetic excitations. The low-temperature thermal oxidation process set out the constructive effect of the oxide layer in the strain relief effect on the overall magnetic response of the corroded specimen. Discussions and conclusions are provided, as well as perspectives regarding the applicability of magnetic non-destructive testing techniques.

Quality assessment method proposal for compacted bentonite clay buffer block using combined non-destructive tests

Quality assessment method proposal for compacted bentonite clay buffer block using combined non-destructive tests

Assessment of foundation damage during earthquakes using acoustic emission monitoring: An experimental study on the shaking table test

Assessing structural foundation damage following an earthquake is critical for safety evaluation. However, assessing the damage to pile foundations with traditional visual inspections and non-destructive testing methods is challenging. This study evaluated the use of acoustic emission (AE) monitoring for damage detection and location in foundation structures during earthquake simulations by conducting shaking table experiments. Scaled models of foundation structures with and without surrounding soil were used in the experiments, and the performance of the AE monitoring system was evaluated by comparing the AE parameters via visual inspection. The experimental results showed that the AE monitoring system could effectively predict the initiation of cracks in foundation structures that experienced an earthquake. In addition, an appropriate filtering criterion for the shaking table experiments was established based on the AE characteristics of the foundation structures during the earthquake simulation, thereby improving the performance of the AE monitoring system for damage location. Consequently, this study contributed to a better understanding of the applicability of AE monitoring systems to foundation structures during earthquakes.

Design and validation of an automated and remote free space measurement system for nondestructive testing of fiber composites

Assessing electromagnetic constitutive parameters is crucial to prescribe the macroscopic properties of composites and their prospective applications. Free space methods are widely used for this purpose, due to their nondestructive/noncontact nature and their applicability on composites incorporating large inclusions or over-frequency bands where waveguide measurements are impractical. However, there still exists issues associated with automation, accurate calibration, remote controlling, and multifunctional characterization. Here, we designed and implemented a microwave-integrated laboratory including a test bench for permittivity/permeability and impedance measurements of individual inclusions and a free space setup for transmission/reflection measurements of fiber-based composites. Easy switching between the bench and antenna measurements was enabled by a homemade RF multiplexer. A three-stage calibration was applied: 2-port error correction (12-term model) of the vector network analyzer and the cables connecting it to the multiplexer, de-embedding of the cables connecting the multiplexer to the switches within the antenna pillars, and thru, reflect, and line (TRL) error correction for the antennas and free space. Exploiting robotics for precise antenna movement and TRL calibration enabled adjustment of the antenna distance to the test frame to a maximum of 2.5 m with a 100 μm accuracy. A multifunctional frame for external stimuli application was also designed. Apart from automation, remote control was realized through user-friendly graphical interfaces and remote access software allowing to swiftly respond to challenges faced during the global pandemic. The free space setup effectiveness was then validated by measuring the transmission/reflection of microwire-based composites from 0.5 to 20 GHz under various magnetic fields.

Research on magnetic flux leakage testing of pipelines by finite element simulation combined with artificial neural network

Magnetic flux leakage (MFL) testing technology is widely employed in non-destructive testing of pipelines, and the analysis of leakage signals plays a crucial role in assessing pipelinea safety. This paper introduces a novel approach for MFL testing, which combines finite element simulation with artificial neural networks. First, a finite element model for MFL testing of defects is established, the influence of magnetization states on MFL signals is discussed, and the variation of signal extremum with magnetization intensity is analyzed. Next, suitable MFL signal features are selected to focus on the relationship between defect types, defect sizes, and these features. Finally, a kernel extreme learning machine (KELM) predictive model is developed to classify defect types and predict defect sizes. The results indicate that as magnetization intensity increases, the magnetization process of the pipeline can be divided into a nonlinear growth phase and a linear phase, with MFL signal extremum rapidly increasing and then gradually growing linearly. Different geometric features of defects correspond to distinct distributions of MFL signals, effectively reflecting variations in defect types and sizes. Compared to traditional ELM models, the KELM model achieves higher prediction accuracy and stable performance, with the radial basis kernel function significantly enhancing the generalization and predictive capabilities of the neural network.

DETERMINATION OF BRIDGE BEAMS SERVICEABILITY USING NON-DESTRUCTIVE TESTING METHODS AND FIELD TESTS

The case of determining the serviceability of bridge beams with manufacturing defects is considered. Based on the results of visual inspection and non-destructive testing, it was found that the defects have a minor impact on the performance of the beams, and the characteristics of the building materials are high. The results of the calculations showed that the beams had almost twice the safety margin compared to the design requirements. The results of field tests of beams showed reliable anchoring of the working reinforcement, proper deformability and crack resistance of the beams. Usage of the acoustic emission method during field tests allowed to establish that the beams had no internal defects that could develop under load and reduce performance. Based on the results of the research, it was concluded that the beams manufactured with defects are suitable for use after the defects have been repaired.

New in assessing the fire resistance of reconstructed reinforced concrete ribbed building panel

The article describes the innovative application of a methodology for assessing the design fire resistance of a reconstructed reinforced concrete ribbed floor panel based on the criterion of the occurrence of a limit state based on loss of load-bearing capacity. In this case, the fire resistance limit of a bending element is established without thermal force destruction based on a set of single quality indicators of structural concrete and reinforcing steel, which simplifies engineering calculations and reduces the cost of expensive experiments. The results of a study of the influence of the geometric dimensions of a reconstructed reinforced concrete ribbed panel, the heating scheme of the design section in fire conditions, the placement of the main and additional reinforcement in the design section, the depth of the cores of the main and additional reinforcement and the degree of its fire protection, the thermal diffusion coefficient of structural concrete, the magnitude of the test load on the panel are presented. and the intensity of stress in the rods of longitudinal working reinforcement to the design fire resistance indicator, which is established based on the loss of load-bearing capacity. The use of the new proposed technical solution makes it possible to determine the design fire resistance of a reconstructed reinforced concrete ribbed panel without natural thermal force effects, simplifies engineering calculations, increases the reliability of statistical quality control of reinforced concrete materials and non-destructive tests, and reduces experimental costs.

An innovation in the method of assessing the fire resistance of a reinforced concrete girderless ceiling of a building

The article presents a new method for assessing the fire resistance of monolithic girderless non-accumulating floors of buildings and structures. The essence of the method lies in the fact that thermal (fire) tests of the floor are carried out without destruction, according to a set of single indicators of the quality of working fittings and structural concrete of continuous slabs. The use of the method makes it possible to determine the fire resistance of an uncut reinforced concrete slab of a girderless ceiling of a building without full-scale fire exposure, increases the reliability of statistical quality control and non-destructive testing, reduces economic costs.

A compact X-ray source via fast microparticle streams.

The spatiotemporal resolution of diagnostic X-ray images is limited by the erosion and rupture of conventional stationary and rotating anodes of X-ray tubes from extreme density of input power and thermal cycling of the anode material. Conversely, detector technology has developed rapidly. Finer detector pixels demand improved output from brilliant keV-type X-ray sources with smaller X-ray focal spots than today and would be available to improve the efficacy of medical imaging. In addition, novel cancer therapy demands for greatly improved output from X-ray sources. However, since its advent in 1929, the technology of high-output compact X-ray tubes has relied upon focused electrons hitting a spinning rigid rotating anode; a technology that, despite of substantial investment in material technology, has become the primary bottleneck of further improvement. In the current study, an alternative target concept employing a stream of fast discrete metallic microparticles that intersect with the electron beam is explored by simulations that cover the most critical uncertainties. The concept is expected to have far-reaching impact in diagnostic imaging, radiation cancer therapy and non-destructive testing. We outline technical implementations that may become the basis of future X-ray source developments based on the suggested paradigm shift.

Ex Vivo Biomechanical Comparison of Four Techniques to Tibiotarsus Osteosynthesis in Adult Laying Hens (Gallus gallus domesticus).

To assess the biomechanical parameters of intact tibiotarsi (INT) and tibiotarsi with a 5-mm segmental diaphyseal defect repaired using four osteosynthesis techniques: a locking plate (LP), a plate-rod combination, an external skeletal fixator (one end-threaded positive-profile pin per fragment) with an intramedullary pin tie-in (TIF 1), and an external skeletal fixator (two end-threaded positive-profile pins per fragment) with an intramedullary pin tie-in (TIF 2). Sixty tibiotarsi from 30 adult laying hens were allocated into five groups for nondestructive dynamic torsion and four-point bending tests, followed by failure tests. Nondestructive dynamic tests evaluated stiffness over time in torsion and bending. Torsion destructive tests provided maximum torque and rotation values, whereas the four-point bending tests provided the yield load, maximum bending load, and maximum displacement. The INT group showed higher torsional stiffness and maximum torque but similar bending stiffness, torsional strength, and bending strength in one or more groups. LP and TIF 2 exhibited the highest similarity frequencies among the treatment groups, whereas the TIF 1 group displayed lower stiffness and strength for most of the evaluated parameters. Similar results for LP and TIF-2 groups suggest the biomechanical equivalence of these methods for tibiotarsal osteosynthesis in adult hens.

Investigation of mechanical characteristics and sustainable practices in concrete incorporating recycled marble waste

Due to the rapid expansion of infrastructure, urbanization, and industry, there is a constant need for concrete worldwide. However, the expansion of the concrete sector increases pressure on natural resources, endangering the balance of the ecosystem. Thus, it would be advantageous to meet current concrete needs without reducing production quality by incorporating recycled materials into concrete mixes. In this work, we investigate the mechanical characteristics of environmentally friendly concrete using recycled marble powder (WMP) partially replacing cement and marble coarse aggregates (MCA) as an alternative to natural coarse aggregates. The qualities of the concrete were evaluated using a combination of destructive and non-destructive testing techniques. In this study, three series of mixes were prepared. The first series (S1) is composed of 100% natural coarse aggregates. In the second series (S2), 50% of the natural coarse aggregates are substituted for marble coarse aggregates, while the third series (S3) is composed of 100% marble coarse aggregates. In each of the three series, Marble powder was used in place of cement at a percentage ranging from 5% to 20%, increasing by 2.5%. Concrete mixes were developed and evaluated with different levels of marble waste substitution to compare their compressive strengths and workability to those of traditional concrete made from 100% natural aggregates. Simultaneously, the strength characteristics were measured using the Schmidt hammer and ultrasonic velocity tests. As was mentioned, in the three series, when Cement is replaced with marble powder, the slump decreases, even though the incorporation of marble coarse aggregates tends to increase this workability, while the compressive strength shows an increase of 28.66% and 31.63% compared to the control mix for 50% and 100% substitute of natural coarse aggregates with marble coarse aggregates, respectively. It is also noteworthy that concrete containing marble waste exhibits normal ultrasonic velocity. For concrete mixtures of series (S1), (S2), and (S3), respectively, the velocity of ultrasonic pulses increased by 18.20%, 27.44%, and 27.98%, while the Schmidt Rebound Number increased by 10.13%, 14.52%, and 21.37%, respectively, in contrast to the values of the control mixture. Additionally, the reliability of results from the universal testing machine (UTM) was validated through correlation analysis of compressive strength measurements obtained by various methods. The study's findings are intriguing and underscore the potential of employing marble waste as an alternative to natural aggregates.

Study on intelligent recognition of urban road subgrade defect based on deep learning.

China's operational highway subgrades exhibit a trend of diversifying types and an increasing number of defects, leading to more frequent urban road safety incidents. This paper starts from the non-destructive testing of urban road subgrade defects using geological radar, aiming to achieve intelligent identification of subgrade pathologies with geological radar. The GprMax forward simulation software is used to establish multi-layer composite structural models of the subgrade, studying the characteristics of geological radar images for different types of subgrade diseases. Based on the forward simulation images of geological radar for subgrade defects and field measurement data, a geological radar subgrade defect image database is established. The Faster R-CNN deep learning algorithm is applied to achieve target detection, recognition, and classification of subgrade defect images. By comparing the loss value, total number of identified regions, and recognition accuracy as metrics, the study compares four improved versions of the Faster R-CNN algorithm. The results indicate that the faster_rcnn_inception_v2 version is more suitable for the intelligent identification of non-destructive testing of urban road subgrade defects.

A genetic algorithm with tabu search method for 3 dimensional detect profile reconstruction using MFL measurement.

In nondestructive testing, magnetic flux leakage (MFL) inspection is extensively employed for the inversion of pipeline defects. Exact reconstruction of the defect plane with measurements is a pressing issue in the field of MFL detection. This article proposes a method that incorporates a layer-by-layer genetic algorithm with tabu search (GA-TS). During the iterative process, our objective is to utilize a tabu search based on evolutionary algorithms to avoid local optimal solutions, obtain global optimal solutions, and reconstruct defects with enhanced accuracy. In addition to enhancing the accuracy of pipeline defect categorization, our approach has two significant limitations: its limited global search capability and slow convergence rate. Finally, the method is evaluated via experiments in which MFL signals obtained from an experimental platform and simulation signals are used. Practical results and a thorough comparative study of alternative approaches confirm the model's superiority.

Non‐Destructive and Mechanical Characterization of the Bond Quality of Co‐Extruded Titanium‐Aluminum Profiles

The transportation industry aims to improve energy efficiency and reduce CO2 emissions, with a focus on reducing vehicle mass. A key method involves advanced lightweight construction techniques using materials like aluminum alloys. Research is concentrated on developing processes to combine different materials into reinforced hybrid components, such as aluminum and titanium. This study focuses on the lateral angular co‐extrusion (LACE) process to produce hybrid hollow profiles of EN AW‐6082 and Ti6Al4V, investigating the impact of the thermomechanical processing during extrusion and heat treatment (HT) on the resulting bond quality and material properties. Various HT routes are tested to see their impact on intermetallic phase formation, longitudinal weld seams, and bonding strength. Mechanical testing evaluates the tensile strength of the joining zone, while nondestructive ultrasonic testing (UT) assesses joining zone integrity and poor bonding detection. Results indicate that HT parameters significantly influence the bond quality and mechanical properties of hybrid profiles. UT data shows a strong correlation with tensile strength and intermetallic phase growth, providing a nondestructive way to evaluate bond quality. This study highlights the potential of LACE processes and optimized HT strategies to improve the performance and reliability of aluminum–titanium hybrid components.

Adaptive Multi-Scale Bayesian Framework for MFL Inspection of Steel Wire Ropes

Magnetic flux leakage (MFL) technology is widely used in steel wire rope (SWR) inspection for non-destructive testing. However, accurate defect characterization requires advanced signal processing techniques to handle complex noise conditions and varying defect types. This paper presents a novel adaptive multi-scale Bayesian framework for MFL signal analysis in SWR inspection. Our approach integrates discrete wavelet transform with adaptive thresholding and multi-scale feature fusion, enabling simultaneous detection of minute defects and large-area corrosion. To validate our method, we implemented a four-channel MFL detection system and conducted extensive experiments on both simulated and real-world datasets. Compared with state-of-the-art methods, including long short-term memory (LSTM), attention mechanisms, and isolation forests, our approach demonstrated significant improvements in precision, recall, and F1 score across various tolerance levels. The proposed method showed superior detection performance, with an average precision of 91%, recall of 89%, and an F1 score of 0.90 in high-noise conditions, surpassing existing techniques. Notably, our method showed superior performance in high-noise environments, reducing false positive rates while maintaining high detection sensitivity. While computational complexity in real-time processing remains a challenge, this study provides a robust solution for non-destructive testing of SWR, potentially improving inspection efficiency and defect localization accuracy. Future work will focus on optimizing algorithmic efficiency and exploring transfer learning techniques for enhanced adaptability across different non-destructive testing (NDT) domains. This research not only advances signal processing and anomaly detection technology but also contributes to enhancing safety and maintenance efficiency in critical infrastructure.

Pump-Wavelength Selective All-Optical Terahertz Metasurface with Independent Amplitude and Frequency Modulations.

Tunable terahertz (THz) metasurfaces based on optical control are crucial in high-speed communication, nondestructive testing, and imaging. However, realizing independent optical tunability of multiple functions in the THz band remains challenging due to limitations in control materials. Here, we experimentally demonstrate a novel THz metasurface that employs two control materials combined with an electric-field-coupled inductor capacitor microstructure to achieve all-optical independent modulations of amplitude and frequency. Amplitude modulation is achieved through near-infrared optical pumping, reaching a maximum modulation depth of 94.42%. Broadband frequency modulation, spanning 0.21 THz, is accomplished using visible light pumping. The independent modulation function is owing to the odd-order nonlinear polarization characteristics of perovskite and the selective photon transition between the bottom Si island and the perovskite film. This work introduces a novel approach for all-optical independent modulation of THz devices, offering valuable insights for developing all-optical metasurfaces, intelligent light windows, and multidimensional ultrafast switches.

Investigation on the variations of dynamic characteristics of anchor bolts considering transverse inertia effects under tensile loads

Abstract In the case where tunnel anchor bolts are located in strata with limited surrounding rock boundaries, the response signals of the anchor bolts are affected by the tensile load and the transverse inertia effect, resulting in a decrease in the reliability of the non-destructive testing (NDT) results. To accurately assess the anchorage quality under these disturbances, a vibration energy loss model for anchor bolts after excitation was proposed. NDT experiments and numerical simulation studies were conducted on intact and defective anchor bolts under different conditions, analyzing the variation patterns of structural dynamic characteristics such as the the first-order natural frequency, the first-order damping ratio, and the vibration energy loss under the influence of tensile load and transverse inertia effect. The results show that during the gradual increase of the tensile load, the first-order natural frequency and the first-order damping ratio exhibit an overall trend of first increasing and then decreasing, while the rate of the energy loss initially decreases and then increases. The presence of anchorage defects leads to a reduction in the first-order natural frequency, the first-order damping ratio, and the energy loss of the anchor bolt. As the transverse inertia effect intensifies, the first-order natural frequency initially increases and then decreases, the first-order damping ratio decreases, and the energy loss initially decreases slightly before increasing. The numerical simulation verifies the applicability of the theoretical model and explores the influence of defect location on energy loss. The results indicate that the closer the defect location is to the free end, the less the vibration energy loss of the anchor bolt.

Data fusion of ultrasonic and thermal nondestructive testing of metal-polymer composite

Non-destructive testing is an integral part of quality inspection for critical products. The complex structure of metalpolymer hydrogen cylinders makes it difficult to reliably detect defects using a single type of an NDT technique. In this context, the application of hybrid NDT is of interest. This paper considers the combined use of acoustic and thermal techniques of defect detection and the fusion of their results. Experimental verification has shown that the fusion of thermal and acoustic inspection data using the approach developed in this study provides an increase in defect detection compared to the separate use of these types of NDT methods.

Failure Analysis of Girth Weld Cracking in Gas Transmission Pipelines Subjected to Ground Subsidence and Traffic Loads

Girth welds are weak points in pipelines, and failures occur frequently. In a gas transmission pipeline, a girth weld experienced cracking, prompting a failure analysis using experimental methods and finite element analysis (FEA). Experimental results showed that X-ray non-destructive testing (NDT) revealed cracks, porosity, and lack of fusion in the girth weld. However, the hardness and microstructure of the material showed no abnormalities. During operation, the pipeline experienced an increase in soil cover and was subjected to ground subsidence and vehicle loads. Finite element analysis was conducted on the defective girth weld under different conditions, including varying soil cover depths, different levels of subsidence, and varying vehicle loads, to examine the pipeline’s stress response. The results indicated that the combination of soil cover, subsidence, and vehicle loads led to pipeline failure, whereas none of these factors alone was sufficient to cause girth weld failure. To prevent such failures from occurring again, the following measures are recommended: strengthen on-site welding quality control of girth welds, conduct inspections for defects in girth welds of in-service pipelines, and promptly address any defects that exceed acceptable limits.

Modeling of reflected ultrasonic fields in composed samples

Ultrasonic nondestructive testing involves the study of propagation, reflection and refraction patterns of elastic waves excited by contact or non-contact piezoelectric transducers in the inspected object. The finite element modeling usually requires high computational costs and additional postprocessing to select individual waves from the total solution. When probing joints of homogeneous materials, such as turbine blades made of heat-resistant monocrystalline alloys, the joint boundary is low-contrast, and the reflected signals are relatively weak. This causes additional difficulties for their separation from the total wave field and correct interpretation of the information they bring. To solve this problem, explicit asymptotic representations for reflected and transmitted waves in a two-layer elastic half-space with a surface source are proposed in the present work, which allow fast parametric analysis. They can be used to analyze ultrasonic probing data, for example, to estimate the state of the junction zone or to determine the mutual orientation of the crystals’ principal axes.