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Visualization of surface wave based on signal and imaging processing schemes is an efficient way to enhance the detectability of ultrasonic testing for inspection of surface or near surface small defect in layered structures such as the thermal barrier coating (TBC) system. A full wave field measurement is necessary to get information for visualization of the ultrasonic wave. In this paper, a non-contact, array pickup electromagnetic acoustic transducer (EMAT) with 32 receiving coils and a phased array EMAT system are developed for efficient measurement of full information of surface wave field. Based on the multiple channel EMAT signals at different scanning position, a dynamic visualization algorithm is developed to image the propagation, reflection and scattering wave caused by defect and structure edges. The validities of the array pickup EMAT and the dynamic visualization algorithm are demonstrated by using both simulated and measured surface wave signals for a prototype array EMAT and an aluminum plate with small hole defect.

In this paper, a novel Phased Array fully Flexible Rayleigh-wave EMAT (PAFR-EMAT) suitable for inspection of curved surface based on flexible coil bias field magnet EMAT is proposed. The PAFR-EMAT consists of a flexible racetrack coil generating long pulsed bias magnetic field instead of the conventional permanent magnets, and flexible meander coils triggered in sequence to induce transient eddy current for exciting enhanced Rayleigh wave of MHz frequency. Based on the Lorentz force mechanism, pulsed electromagnetic fields and the generated ultrasonic waves of the proposed new EMAT are studied through numerical simulation at first. Experiments are conducted then to check the practical performance of the PAFR-EMAT for pipe inspection. Results show that the PAFR-EMAT has good performance in Rayleigh wave generation for inspection of the curved surface of metallic pipe and is capable to detect surface crack of small depth.

In this paper, inversion schemes for reconstruction of load and constraint of pipeline structure of a liquid rocket engine for global vibration evaluation of pipelines have been proposed and validated. The method involved modeling for forward simulation of random vibration and a multistep inversion scheme to reconstruct the unknown load and constraint parameters. In parallel, a piping structure vibration experimental system was also established to acquire the measured vibration signals for experimental validation of the numerical method. From both the numerical and experimental results, it was verified that a fine finite element model of a pipeline structure can be established based on the reconstructed load and constraint parameters which enabled a global vibration evaluation of the pipeline structure based on limited vibration information.

The present study investigated the association between the presence of periodontitis and aortic calcification (AC) risk among Chinese adults. A total of 6059 individuals who underwent regular health check-ups and received a diagnosis of periodontitis between 2009 and 2016 were included. The outcome was AC, assessed by a chest low-dose spiral CT scan. Cox proportional hazards regression analysis was used to assess the association between periodontitis and AC risk after adjusting for several confounders. After a median follow-up period of 2.3 years (interquartile range: 1.03–4.97 years), 843 cases of AC were identified, with 532 (12.13%) and 311 (18.59%) patients in the non-periodontitis group and periodontitis group, respectively. Multivariate analyses demonstrated that, compared with those without periodontitis, the hazard ratio and 95% confidence interval for AC risk in participants with periodontitis was 1.18 (1.02–1.36) ( P = .025) in the fully adjusted model. Stratified analyses showed that the positive relationship between periodontitis and AC was more evident in males and participants interaction = .005 and .004, respectively). Our results show that the presence of periodontitis was positively associated with AC among Chinese adults, especially among males and younger participants.

Structures of nonmagnetic materials are broadly used in engineering fields such as aerospace, energy, etc. Due to corrosive and hostile environments, they are vulnerable to the Subsurface Pitting Corrosion (SPC) leading to structural failure. Therefore, it is imperative to conduct periodical inspection and comprehensive evaluation of SPC using reliable nondestructive evaluation techniques. Extended from the conventional Pulsed eddy current method (PEC), Gradient-field Pulsed Eddy Current technique (GPEC) has been proposed and found to be advantageous over PEC in terms of enhanced inspection sensitivity and accuracy in evaluation and imaging of subsurface defects in nonmagnetic conductors. In this paper two GPEC probes for uniform field excitation are intensively analyzed and compared. Their capabilities in SPC evaluation and imaging are explored through simulations and experiments. The optimal position for deployment of the magnetic field sensor is determined by scrutinizing the field uniformity and inspection sensitivity to SPC based on finite element simulations. After the optimal probe structure is chosen, quantitative evaluation and imaging of SPC are investigated. Signal/image processing algorithms for SPC evaluation are proposed. Through simulations and experiments, it has been found that the T-shaped probe together with the proposed processing algorithms is advantageous and preferable for profile recognition and depth evaluation of SPC.

Coated conductive structures play an important role in such industrial fields as aerospace, energy, chemical engineering, etc. Because of the corrosive and hostile environments, the corrosion which is normally hidden under the conductor coating, occurs in the surface of the in-service structure. It poses a severe threat to the integrity and safety of the structure. Therefore, it is imperative to effectively detect and quantitatively evaluate the hidden corrosion via Non-destructive Evaluation (NDE) techniques. Pulse-modulation Eddy Current technique (PMEC) has been identified to be superior to other electromagnetic NDE methods, particularly regarding evaluation and imaging of corrosion. Whereas, the acquired corrosion images hardly indicate the true opening profile of the corrosion. This hinders the quantitative evaluation of the corrosion. In light of this, in this paper PMEC along with the image processing technique for imaging and evaluation of corrosion in coated conductors is intensively investigated. The image processing technique is proposed based on Theta Map (TM) which is a processing method for quantifying the source parameters of magnetic data that describe the anomalous structure. The validity of PMEC combined with modified TM for profile recognition and assessment of hidden corrosion in nonmagnetic structures is identified via experiments.

Reduced Activation Ferritic/Martensite (RAFM) steel is a new material considered to be one of the important candidate structural materials for Tokamak fusion reactors. Plastic deformation inevitably occurs during the operation of fusion reactors due to giant unexpected loads. To ensure the structural integrity, reliable non-destructive evaluation (NDE) for RAFM steel is of great importance. Magnetic Barkhousen Noise (MBN), Magnetic Incremental Permeability (MIP) and Magnetic Flux Leakage (MFL) methods are found being effective especially for NDE of large plastic deformation in RAFM steel by authors. Its feasibility for small plastic deformation under 1%, however, is not clarified. At the same time, as mechanical damage may be caused by several times of large load, i.e., the current deformation state is possibly of complicated loading history. To clarify the influence of these factors is also very important for application of these magnetic NDE methods in practice. In view of this background, the influences of plastic deformation history on NDE signals and the feasibility of the magnetic NDE methods for relative small deformation are experimentally studied in this paper. From experimental results, it was found that the MIP and MFL signals decrease with an enlarged plastic deformation and are not significantly influenced by the plastic deformation history, while the MBN signals show significantly different tendency for specimen of different loading history. To understand the mechanism, micro-structure analyses and magnetic domain observations are conducted by using the EBSD and the magnetic powder-pattern method. Observation results reveal that the pinning effect of the micro defects prevents the movement of magnetic domain walls and perturbs the signals of magnetic NDE methods, especially on the MBN signals. These results show that the MIP and MFL method are more suitable for evaluation of plastic deformation in RAFM steel from practical application point of view.

Manikins have traditionally been used to train ultrasound-guided Central Venous Catheterization (CVC), but are static in nature and require an expert observer to provide feedback. As a result, virtual simulation and personalized learning has been increasingly adopted in medical education to efficiently provide quantitative feedback. The Dynamic Haptic Robotic Trainer (DHRT) trains surgical residents in CVC needle insertions by simulating various patient profiles and presenting personalized feedback on objective performance. However, no studies have examined the learning gains of the personalized learning feedback or the relation of feedback to what the user is focusing on during the training. Thus, this study was developed to determine the effectiveness of the current personalized learning interface through a long-term investigation with 7 surgical residents. The eye tracking analysis showed that residents spent significantly more time fixated on percent aspiration throughout the study; the more time participants spent looking at the Number of Insertions, Percent Aspiration and the Angle of Insertion on the DHRT GUI, the better they performed on subsequent trials on the DHRT system.

The influence of tensile stress on hysteresis loop of Reduced Activation Ferrite & Martensitic steel (RAFM steel) in elastic region was quantitatively evaluated through experiments in this paper. In view of in vessel structures of the RAFM steel in the Tokamak devices, the variation of magnetic material properties caused by forces or mechanical deformation may lead to unexpected influences on their dynamical behaviors, even safety problem. In this paper, tensile experiments of a RAFM steel were conducted under magnetic field up to 60 kA/m to measure its hysteresis loops under different tensile stress. Tensile specimens of a RAFM steel developed in China (CLAM steel) were fabricated and measured with a multi-field coupling experimental system. The maximum relative permeability under different experimental conditions was extracted from the measured hysteresis loops. Experimental results show that a clear variation of the maximum magnetic permeability was observed when the external tensile stress was enlarged. In addition, based on a linear theory of magneto-solid coupling mechanics, a model of constitutive relation between tensile stress and maximum magnetic permeability was put forward and validated based on the experimental results.

BACKGROUND: The objective of this study was to determine whether gaze patterns could differentiate expertise during simulated ultrasound-guided Internal Jugular Central Venous Catheterization (US-IJCVC) and if expert gazes were different between simulators of varying functional and structural fidelity. METHODS: A 2017 study compared eye gaze patterns of expert surgeons (n=11), senior residents (n=4), and novices (n=7) during CVC needle insertions using the dynamic haptic robotic trainer (DHRT), a system which simulates US-IJCVC. Expert gaze patterns were also compared between a manikin and the DHRT. RESULTS: Expert gaze patterns were consistent between the manikin and DHRT environments (p = 0.401). On the DHRT system, CVC experience significantly impacted the percent of time participants spent gazing at the ultrasound screen (p < 0.0005) and the needle and ultrasound probe (p < 0.0005). CONCLUSION: Gaze patterns differentiate expertise during ultrasound-guided CVC placement and the fidelity of the simulator does not impact gaze patterns.

High-tech simulators are gaining popularity in surgical training programs because of their potential for improving clinical outcomes. However, most simulators are static in nature and only represent a single anatomical patient configuration. The Dynamic Haptic Robotic Training (DHRT) system was developed to simulate these diverse patient anatomies during Central Venous Catheterization (CVC) training. This article explores the use of the DHRT system to evaluate objective metrics for CVC insertion by comparing the performance of experts and novices.Eleven expert surgeons and 13 first-year surgical residents (novices) performed multiple needle insertion trials on the DHRT system. Differences between expert and novice performance on the following five metrics were assessed using a multivariate analysis of variance: path length, standard deviation of deviations (SDoD), average velocity, distance to the center of the vessel, and time to complete (TtC) the needle insertion. A regression analysis was performed to identify if expertise could be predicted using these metrics. Then, a curve fit was conducted to identify whether learning curves were present for experts or novices on any of these five metrics.Time to complete the insertion and SDoD of the needle tip from an ideal path were significantly different between experts and novices. Learning curves were not present for experts but indicated a significant decrease in path length and TtC for novices.The DHRT system was able to identify significant differences in TtC and SDoD between experts and novices during CVC needle insertion procedures. In addition, novices were shown to improve their skills through DHRT training.

This paper proposes a new crack model to parameterize profile of a natural crack in order to improve the inversion precision of crack profile with eddy current testing (ECT) signals. In this novel crack model, the edge profile of a planar crack is parametrized with six feature parameters of three curves, i.e. two quarter-elliptic curves and a straight line. Compared with the conventional rectangular and semi-elliptical crack model, the new model gives better profile fitting of actual cracks such as a fatigue crack or a stress corrosion crack. In addition, the reconstruction procedure with the new crack model is more stable than using the arbitrary-shaped crack model outlined by a piecewise line as the unknown parameters to be reconstructed is significantly reduced. To apply the new crack model for crack inversion with the conventional conjugate gradient method, the formulae for calculating the gradient vector regarding to the feature parameters of the new crack model are deduced. To investigate the performance of the new model for crack sizing, cracks of different sizes and complex shapes were reconstructed using the new crack model and the fast forward ECT signal simulator using unflawed field database and the multimedia finite element scheme. Meanwhile, inverse analyses for sizing cracks of complicated shapes were also carried out based on ECT signals containing random noise to clarify the robustness of the new inversion scheme. The numerical results show that reconstructed crack parameters are identical with the true ones in acceptable accuracy, which proved the validity and efficiency of the new method.

To compare the effect of simulator functional fidelity (manikin vs a Dynamic Haptic Robotic Trainer [DHRT]) and personalized feedback on surgical resident self-efficacy and self-ratings of performance during ultrasound-guided internal jugular central venous catheterization (IJ CVC) training. In addition, we seek to explore how self-ratings of performance compare to objective performance scores generated by the DHRT system.Participants were randomly assigned to either manikin or DHRT IJ CVC training over a 6-month period. Self-efficacy surveys were distributed before and following training. Training consisted of a pretest, 22 practice IJ CVC needle insertion attempts, 2 full-line practice attempts, and a posttest. Participants provided self-ratings of performance for each needle insertion and were presented with feedback from either an upper level resident (manikin) or a personalized learning system (DHRT).A study was conducted from July 2016 to February 2017 through a surgical skills training program at Hershey Medical Center in Hershey, Pennsylvania.Twenty-six first-year surgical residents were recruited for the study. Individuals were informed that IJ CVC training procedures would be consistent regardless of participation in the study and that participation was optional. All recruited residents opted to participate in the study.Residents in both groups significantly improved their self-efficacy scores from pretest to posttest (p0.01). Residents in the manikin group consistently provided higher self-ratings of performance (p0.001). Residents in the DHRT group recorded more feedback on errors (228 instances) than the manikin group (144 instances). Self-ratings of performance on the DHRT system were able to significantly predict the objective score of the DHRT system (RSimulation training with the DHRT system and the personalized learning feedback can improve resident self-efficacy with IJ CVC procedures and provide sufficient feedback to allow residents to accurately assess their own performance.

Plastic deformation and fatigue damage, as the typical micro-damage caused by external loads such as earthquake and long-term process of liquid flow/stress, may seriously affect the material electromagnetic properties and shorten the structural lifespan. In this paper, first, the correlation between the material electromagnetic properties and the plastic deformation is investigated for a 304 austenitic stainless steel, and the mechanism is discussed based on the microstructure analysis. It is indicated that the increasing of plastic deformation leads to the material conductivity decrease which is considered to relate to the micro-defects including slip and twins, while the increasing of plastic deformation leads to the material magnetic property increase that has a close relationship with the martensitic transformation. Moreover, the influence of fatigue damage on the material electromagnetic properties and the microstructure analysis (slips, twins, and martensitic transformation) are also confirmed. Finally, the combined effect of plastic deformation and fatigue damage is also investigated through experiment. Besides, the difference of microstructures of three kinds of damage specimens is observed and analyzed.

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Magnetic Barkhausen Noise (MBN) method is known as an effective nondestructive evaluation (NDE) method for evaluation of residual stress in ferromagnetic materials. Some studies on the feasibility of the MBN method for NDE of residual strains were also conducted and found applicable. However, these studies are mainly focused on the state of residual strains which were introduced through a one-cycle-loading process. In practice, however, structures may suffer from an unpredictable and complicated loading history, i.e., the final state of plastic strain may be induced by several times of large loads. Whether the loading history has influences on MBN signals or not is of great importance for the practical application of the MBN method. In this paper, several ferromagnetic specimens with the same final state of residual strain but of different loading history were fabricated and inspected by using a MBN testing system. The experimental results reveal that the loading history has a significant influence on the detected MBN signals especially for a residual strain in range less than 1%, which doubts the feasibility to apply the MBN method simply in the practical environment. In addition, micro-observations on the magnetic domain structures of the plastic damaged specimens were also carried out to clarify the influence mechanism of loading history on the MBN signals.

Background The objective of this study was to validate the transfer of ultrasound-guided Internal Jugular Central Venous Catheterization (US-IJCVC) placement skills from training on a Dynamic Haptic Robotic Trainer (DHRT), to placing US-IJCVCs in clinical environments. DHRT training greatly reduces preceptor time by providing automated feedback, standardizes learning experiences, and quantifies skill improvements. Methods Expert observers evaluated DHRT-trained (N = 21) and manikin-trained (N = 36) surgical residents on US-IJCVC placement in the operating suite using a US-IJCVC evaluation form. Performance and errors by DHRT-trained residents were compared to traditional manikin-trained residents. Results There were no significant training group differences between unsuccessful insertions (p = 0.404), assistance on procedure (p = 0.102), arterial puncture (p = 0.998), and average number of insertion attempts (p = 0.878). Regardless of training group, previous central line experience significantly predicted whether residents needed assistance on the procedure (p = 0.033). Conclusion The results failed to show a statistical difference between DHRT- and manikin-trained residents. This study validates the transfer of skills from training on the DHRT system to performing US-IJCVC in clinical environments.

W/Cu divertor has complex structure and faces extreme work environment in EAST Tokamak device. To measure its thermal strain shall be a valued way to understand its service behavior and then optimize its design and manufacturing process. This work presents a preliminary study on measuring thermal strain of EAST W/Cu divertor structure using electric resistance strain gauges. Eight gauges had been used in the experiment and the heating temperature had been set to 230 °C with respect to the work temperature. To realize the measuring experiment, an appropriate fixing method of gauges in divertor narrow spaces had been taken and tested, which could not only withstand high temperature but also had no damage to the divertor sample. The measurement results were that three gauges showed positive strain while other three showed negative strain after having been compensated, which corresponded to tensile stress and compressed stress respectively. Two thermomechanical simulations had also been carried out and used for comparing with the experiment.

Nuclear power plant (NPP) is the final goal of the research and developments on the controlled nuclear fusion technologies. Small-diameter tubes, such as the mono-block tubes in divertors, are widely used in Tokamak fusion reactors and other NPPs. To ensure safety of controlled fusion reactors, pre-service and in-service non-destructive testing (NDT) for small-diameter tubes are of great importance. In view of this background, this paper proposes a new array eddy current testing (ECT) probe of high efficiency and detectability aiming for NDT of the small-diameter tubes. The excitation unit of the probe contains large coils of spiral configuration, and the pick-up unit consists of four small pancake coils with rectangle arrangement. The detection signal is taken as the specific difference of the outputs of the pick-up coils. The unique coil arrangement and signal mode can significantly reduce the wobbling noise due to both the probe lift-off change and inclination. The validity and efficiency of the probe configuration are verified in this paper through numerical simulation and experiments. A hybrid FEM-BEM code of A-φ formulation is adopted in the ECT signal simulation, and experiments are conducted by using simplified probe for plate specimen and an array ECT instrument. Both the simulation and experimental results reveal that the configuration of new array ECT probe is capable to detect both axial and circumferential crack in either inside or outside surface of a small-diameter tube.

This paper introduces an experimental progress of the magneto-elastoplastic coupling phenomenon on magnetic flux leakage signal for ferromagnetic materials. The magnetic flux leakage signal on the surface of medium carbon steel was measured under the combined action of elastic load and plastic deformation. Based on the experimental results, the influences of elastic load and plastic deformation on the magnetic flux leakage signal and their coupling effects were analyzed. A theoretical mechanism of experimental phenomena was explained by the magneto-elastoplastic coupling model and magnetic charge model. The results show that the magnetic flux leakage signal increases with the increase of the elastic load, and the magnetic flux leakage signal increases first and then decreases with the increase of plastic deformation. As the elastic load increases, the effect of plastic deformation on the magnetic flux leakage signal gradually increases. The work in this paper provides a vigorous support for the safety evaluation of engineering structures caused by the combination of plastic deformation and residual stress through magnetic flux leakage signal.

Deformation and contact force of the fuel assembly due to thermal gradient are of great concerns to the integrity design and safe operation of the core in the China Fast Reactor (CFR). Up to now, only the 2D deflection measurement of the sub-assemblies has been investigated, and almost no attention is paid to the contact force measurement between the sub-assemblies with a small clearance. In this paper, the measurement method and system are developed for measuring the deformation and contact force of the fuel assembly under thermal gradient with the test fuel assembly simplified based on the stiffness equivalent strategy. In addition, the 3D deformation and contact force are measured through the non-contact industrial photogrammetry system and the thin film pressure sensor or strain gauge, respectively. Free thermal bowing test for a single assembly is performed at first for verifying the reliability of the 3D deformation measurement by comparing with the results of finite element (FE) simulation. Afterwards, the 3D deformation and the contact force are measured for the single assembly restrained thermal bowing test. The accuracy of the proposed contact force measurement is investigated through comparison with the method of spoke-type force sensors. The developed measurement method and system can provide experimental basis for safety design of the CFR due to its potential for comprehensive deformation and contact force measurements.

The ITER facility currently incorporates two types of In Vessel Coils (IVC) as a method of stabilizing “Edge Localized Modes” (ELM) and providing “Vertical Stabilization” (VS). To withstand the severe conditions, the IVCs are made of stainless steel mineral insulated conductor (SSMIC). The jacket of the SSMIC is modified stainless steel 316LN. The diameter is 59mm and thickness is only 2.5mm. In order to join the IVC coils, it is necessary to develop the joints manufacturing. Jacket welding is an important process of the joints manufacturing. Based on the structural analysis, the maximum acceptable defect sizes inside the jacket weld were defined. This paper presents the non-destructive examination (NDE) development of the jacket weld NDE is the thin thickness which will cause the scattering of sound waves and lead the difficulty of effective identification of defects. Phased Array Ultrasonic Test (PAUT) and eddy current test (ECT) were developed for the jacket welds inspection. The results indicated the feasibility of the PAUT and ECT method could solve the problem of the thin thickness tube weld inspection.

The flow of creative ideas throughout the engineering design process is essential for innovation. However, few studies have examined how individual traits affect problem-solving behaviors in an engineering design setting. Understanding these behaviors will enable us to guide individuals during the idea generation and concept screening phases of the engineering design process and help support the flow of creative ideas through this process. As a first step towards understanding these behaviors, we conducted an exploratory study with 19 undergraduate engineering students to examine the impact of individual traits, using the Preferences for Creativity Scale (PCS) and Kirton’s Adaption-Innovation inventory (KAI), on the creativity of the ideas generated and selected for an engineering design task. The ideas were rated for their creativity, quality, and originality using Amabile’s consensual assessment technique. Our results show that the PCS was able to predict students’ propensity for creative concept screening, accounting for 74% of the variation in the model. Specifically, team centrality and influence and risk tolerance significantly contributed to the model. However, PCS was unable to predict idea generation abilities. On the other hand, cognitive style, as measured by KAI, predicted the generation of creative and original ideas, as well as one’s propensity for quality concept screening, although the effect sizes were small. Our results provide insights into individual factors impacting undergraduate engineering students’ idea generation and selection.

Engineering organizations around the word are increasingly becoming team-based due to a teams’ ability to generate solutions to complex problems. This is thought to be attributed to the “wisdom of the collectives” where teams outperform the sum of their individual members. Despite heavy emphasis of teamwork in engineering design, our understanding of how to cultivate teamwork skills is poorly understood. This is due in part to the fact that research on engineering design teams is often based on ‘snap-shot’ ethnographic methods that do not account for the dynamic changes that happen over the course of a project. Research that does account for these interactions are hindered by the human processing required to code and analyze the immense amounts of video data acquired through team studies. Recent technological advances in the way of sociometric badges provide a potential avenue to explore intricate communication patterns and help researchers identify when and how team interventions should be developed. However, these technologies have not been validated for use in the dynamic context of engineering design teams. Thus, the current study was developed to examine sociometric badges for their accuracy, precision, and ability to determine speech dominance in engineering design teams. Our results show that sociometric badges can accurately capture total speaking time. However, the results also show that environmental conditions can impact their accuracy. In addition, we found that sociometric badges did not capture speech precisely and often overestimated when a team member was speaking. These results support the use of sociometric badges for capturing high level team interactions (e.g. participation and total speaking time) in engineering design research.

China Fast Reactor (CFR) is under construction, and the section stiffness and bending stiffness of CFR assemblies remain unknown and need to be investigated to support the core restraint system design and reactivity safety assessment. In this study, assembly compression tests were performed with three types of test samples. With the compression load varying from 0 to 6 kN, the compressive deformations were measured and the section stiffness were obtained. In assembly bending tests, there were two types of assemblies considering different spike clearances, and the horizontal loads from 400 N to 1900 N were applicable to the upper-load-pad, lower-load-pad and mid-fissile-region level of the assemblies. Assembly deflections were measured and correlations for the load-deflection ratio were proposed. Comparison of theoretical and experimental bending stiffness were carried out, which indicated that the spike clearance has to be taken into consideration in the assembly deformation analysis codes.

To explore the mechanism of damage-induced magnetization for paramagnetic austenitic stainless steel, the differ- ences of damage-induced magnetizations between an austenitic stainless steel and a carbon steel are experimentally studied. Various plastic strains are introduced into the test-pieces of the austenitic stainless steel of 304 type and S185 carbon steel material. The residual plastic strains and the damage-induced magnetic fields nearby the test-pieces, the volume fraction of the damage-induced ferromagnetic martensitic phase in austenitic stainless steel test-pieces are measured. The relationships be- tween the residual plastic strain and the damage-induced magnetic field of two materials are investigated and their differences are compared. In addition, by establishing the relationships of the damage-induced magnetic field with the damage-induced martensitic phase, the effect of the phase transformation on the damage-induced magnetization of austenitic stainless steel is analyzed.

Plastic deformation, as a type of micro-damage caused by external loads such as earthquake, is necessary to be evaluated by using an efficient non-destructive evaluation technique in order to guarantee the structural safety. In this paper, the feasibility of the pulsed eddy current testing method for evaluating the plastic deformation in an austenitic stainless steel has been studied through experiments and simulations. Moreover, the electromagnetic property variations due toplastic deformation have also been investigated.

Non-destructive evaluation (NDE) techniques are indispensable for inspection of damage in structures of carbon steel, which is widely used in many industries. In this paper, experimental and numerical studies were conducted to investigate the electromagnetic property variations of carbon steel Q195 due to plastic strain by using the 4-probe potential drop method and ECT aiming at NDE applications. A series of specimens were fabricated and uniform global plastic strains of different levels were introduced to the specimens by tensile testing. 4-probe potential drop measurements were carried out to obtain the conductivity information at first. It is found that the macro conductivity is not affected significantly by the plastic strain once taking into account the influence of the cross-sectional area reduction of the specimens. Combining the results of numerical analysis using a code of Ar formulation with the measured ECT signals, the permeability of specimens with various plastic damages was evaluated through inverse analysis. It is proved that the ECT signal change due to plastic damages is mainly caused by the variation of permeability, which gives a good possibility to evaluate the plastic damage with a magnetic NDE method.