Search Results (409)

The dynamic distribution of braking forces between front and rear axles in electric commercial vehicles represents a critical multi-objective optimization challenge requiring simultaneous satisfaction of regulatory safety compliance, regenerative energy recovery, thermal stability, and actuator coordination under varying load and road conditions. This paper addresses this challenge through the development and experimental validation of an integrated adaptive brake force distribution strategy combining model predictive control (MPC) with Particle Swarm Optimization (PSO) within a unified framework that ensures compliance with ECE Regulation No. 13. A comprehensive experimental test bench was designed and instrumented, integrating three independent braking mechanisms: magnetic brakes with front and rear torque coefficients of 4.73 N·m/A and 3.65 N·m/A, respectively; an eddy current retarder with coefficient $k_0=$ 2.220 × 10⁻⁴ N·m·s/(A²·rad), producing braking torque that is quadratic in excitation current and linear in rotor speed; a regenerative braking system with 82–90% efficiency; and a switchable magnetic clutch for FWD/4WD operation. The MPC controller was formulated with a prediction horizon $N_p$ = 20, control horizon $N_c$ = 5, and sampling time $T_s$ = 20 ms. PSO was employed for systematic tuning of MPC weights using 30 particles over 50 iterations with cognitive and social coefficients $c_1$ = $c_2$ = 2.0 and linearly decreasing inertia from 0.8 to 0.4. A vehicle state estimation module using Kalman Filtering was developed for real-time estimation of vehicle mass (<3% error), road slope (<0.3% error), and road friction coefficient (<5% error). Experimental validation across eight comprehensive test scenarios demonstrates that the PSO-optimized MPC controller achieves 43% reduction in front RMSE (from 2.65 Nm to 1.52 Nm), 44% reduction in rear RMSE (from 0.78 Nm to 0.44 Nm), 100% ECE R13 compliance (improved from 67.5%), 57% settling time improvement (from 4.2 s to 1.8 s), 92% overshoot reduction (from 67% to 5%), and average recovered energy improvement from 3.51 kJ to 4.04 kJ. The proposed framework provides a comprehensive solution for next-generation electric commercial vehicle brake management systems. Full article

This work presents a numerical framework for the electromagnetic modeling and inverse characterization of laser-hardened steels using 3MA (Micromagnetic Multiparameter Microstructure and Stress Analysis) non-destructive testing. The proposed methodology combines a simplified two-layer eddy current model, representing the hardened case and the softer core, with the Jiles–Atherton hysteresis model. The associated inverse problem is solved by means of a genetic algorithm, enabling the identification of depth-dependent local hysteresis parameters from measured 3MA incremental permeability signals. The Jiles–Atherton hysteresis parameters are first calibrated using bulk B-H loops. Subsequently, the coupled forward model is used to establish the relationship between these parameters and the measured incremental permeability response for different hardening depths. As a proof of concept, the framework is applied to laser-hardened specimens. The identified local hysteresis and permeability characteristics show clear correlations with both case depth and excitation conditions, demonstrating the potential of the proposed approach for physics-based, non-destructive characterization of laser-hardened layers. Full article

The detection of outer-wall defects in thick ferromagnetic structures by conventional pulsed eddy current testing is limited by the shallow penetration depth caused by the high magnetic permeability of ferromagnetic materials. In this study, a magnetic saturation pulsed eddy current testing method is proposed to improve the detectability of such defects. The analytical dependence of the eddy current skin depth on magnetic permeability was first clarified, and finite element simulations were carried out to visualize the effect of magnetic saturation on the magnetic field and eddy current distributions. Pulsed eddy current responses under different relative permeabilities were then numerically analyzed, followed by experimental validation using Q345B steel plates with different thicknesses and cubic Q345B specimens containing flat-bottom hole defects of different depths. The influence of the direction of the saturation magnetic field on testing performance was also investigated. The results demonstrate that magnetic saturation effectively increases eddy current penetration depth and significantly improves the sensitivity of pulsed eddy current testing to wall-thinning defects in thick ferromagnetic structures. Signal separation for different defect depths was markedly enhanced under saturated conditions. In addition, the optimal testing performance was achieved when the saturation magnetic field was parallel to the probe axis. These results, obtained on uncoated specimens under laboratory conditions, provide a validated physical basis and a preferred field-probe configuration for applying magnetic saturation pulsed eddy current testing to thick-walled ferromagnetic components. Full article

Battery autonomy is one of the main factors limiting the endurance of autonomous underwater vehicles (AUVs). Conventional charging through electrical connectors is inconvenient in marine environments since connectors are exposed to corrosion and usually require manual intervention or docking procedures. Inductive wireless power transfer (WPT) avoids these drawbacks, although the conductive nature of seawater introduces additional effects, such as eddy current losses and parasitic capacitance between the coils. These effects modify the resonance conditions of the compensation network and, in turn, reduce the transfer efficiency. This paper presents the design and experimental assessment of an inductive charger for a commercial and specific underwater drone operating under seawater conditions. A square coil geometry, selected to match the available installation area on the vehicle, was analysed together with two compensation networks (LCC-S and LCC-LCC) and two coil designs with 20 and 25 turns. Based on an analytical characterisation, their performance was evaluated for different coil separations and operating temperatures. Among the analysed configurations, the LCC-S topology with 25 turns provided the best compromise between efficiency and tolerance to gap variations. A laboratory prototype was subsequently built and tested in saline water with NaCl concentrations of 2%, 3%, and 4%, reaching an efficiency close to 87% at 266 W. These results confirm that the proposed design is suitable for underwater wireless charging under representative marine salinity conditions. Full article

The accurate determination of the thickness of the metallic coating on steel substrates is essential in industrial quality control. Eddy current testing offers a non-destructive solution by evaluating the impedance or mutual impedance of one or multiple coils. Analytical models exist in the literature for selected sensor configurations. Building on these models, a model-based estimation approach can be applied to derive an estimate for coating thickness and other relevant material and geometry parameters. Conventional setups typically employ wire-wound coils. However, manufacturing tolerances introduce discrepancies between nominal and actual coil geometries, which lead to deviations in the coating thickness estimate. A printed circuit board (PCB)-based coil with lithographically defined geometry achieves substantially tighter fabrication tolerances and higher repeatability than wire-wound coils. In this work, an analytical mutual impedance model for a differential multi-layer PCB pancake coil is derived and validated against established models in the literature with respect to forward modeling accuracy and model-based parameter estimation performance. Furthermore, experimental measurements with two-layer and eight-layer PCB differential coil systems produce parameter estimates with significantly better reproducibility than wire-wound coils. The experimental results show that the two-layer PCB coil achieves close agreement between the absolute estimated parameters and the reference values without requiring additional calibration, while maintaining high sensitivity to coating thickness. Full article

With increasing rail traffic intensity, reliable detection of shallow subsurface rail damage is essential for operational safety. This critical narrative review evaluates non-destructive testing technologies relevant to defects whose active crack front or principal scattering zone lies within the upper approximately 0.5–10 mm of the rail, while treating the 10–15 mm range as a transition to deeper-defect verification. Magnetic flux leakage, magnetic particle inspection, visual inspection, eddy current testing, and conventional ultrasonic testing are first examined as screening or confirmatory comparators. The review then focuses on four ultrasonic surface-wave excitation routes—contact piezoelectric, active air-coupled, electromagnetic acoustic, and laser ultrasonic—and distinguishes source-specific laboratory capability from demonstrated field evidence. Because the cited studies use different defect geometries, rail conditions, sensor configurations, speeds, and decision criteria, their numerical values are reported as source-conditioned evidence rather than as a normalized ranking. An engineering decision matrix links defect depth and size, inspection speed, surface condition, and noise environment to a recommended screening–confirmation workflow. The synthesis identifies contact piezoelectric UT/PAUT as the most mature quantitative confirmation route, while EMAT, air-coupled UT, and laser UT retain method-specific advantages but require stronger natural-defect and in-service validation. Full article

To address the issue of fatigue failure in conventional coil springs applied in automotive suspensions, a design method for a permanent magnet eddy current damper (PMECD) is proposed. Firstly, the working principle of the proposed method is introduced, and its dynamic model is established to identify the key parameters that affect its primary performance. Subsequently, numerical models for repulsive force and eddy current damping force are established. Simulation results show that the system has the characteristics of axial and radial symmetry, and the magnetic yoke and copper sleeve reduce magnetic leakage, thereby verifying the rationality of the structural design of the proposed method. The thicker the permanent magnet, the greater the magnetic force produced, and there exists a nonlinear relationship between the magnetic force and displacement. In comparison, the magnetic force generated increases with the thickness of the copper sleeve, exhibiting a trend of first increasing and then decreasing. With the increase in the air gap, its impact on the magnetic force presents a variation trend of first decreasing, then increasing, and finally decreasing again. Although the increase in speed leads to little change in the magnetic force, the eddy current damping force gradually increases, which in turn results in an increase in solid losses. Test results show that the differences between theoretical and simulation calculations and experimental results are less than 5%, which verifies the correctness of the method; compared with the eddy current damper without a copper sleeve, the equivalent damping ratio of the eddy current damper with a copper sleeve increases by 103.7%. This study provides a theoretical basis for the future design and optimization of PMECDs. Full article

Non-destructive evaluation of surface cracks in Inconel 718 nickel-based alloys operating at high temperatures is crucial for monitoring aero-engine hot-section components. Conventional eddy current testing is often constrained by thermal core degradation and low signal-to-noise ratios, struggling to meet detection requirements in such extreme environments. To address this, this study proposes an optimized absolute probe integrated with an efficient water-cooling system. A multi-physics finite element model was developed to optimize the probe design, focusing on key parameters such as excitation frequency and the geometric dimensions of the coil and ferrite core. Experimental results demonstrate that the optimized probe significantly enhances detection sensitivity over conventional models. Specifically, the peak amplitude increased by 76.2% and the signal-to-noise improved by nearly 10 dB for a 0.3 mm-deep crack. In practical applications, the probe achieves high-sensitivity detection of a 0.3 mm-deep crack at 500 °C. At 600 °C, it reliably detects a 0.5 mm-deep crack with a coefficient of variation not exceeding 3.5% and it retains detection capabilities even at 650 °C. Therefore, this sensor design strategy proves to be a highly viable method for non-destructive evaluation in extreme industrial thermal environments. Full article

The development of advanced high-strength steels (AHSS) for the automotive industry requires optimizing the balance between mechanical properties and durability in aggressive environments. This study investigates the effects of two heat treatment routes on the microstructure and corrosion resistance of a transformation-induced plasticity (TRIP) steel (Fe-0.2C-1.75Mn-0.5Si-1Al). Route A includes a full austenitizing step at 1000 °C prior to intercritical annealing, whereas Route B omits this step and begins directly with intercritical annealing at 800 °C. Microstructural characterization (SEM/XRD), electrochemical assays, and eddy current tests were employed. The results revealed that Route A yields a homogeneous microstructure with 12.7% retained austenite, higher than the 7.7% obtained with Route B. Electrochemically, the steel from Route A exhibited the greatest resistance, with the lowest corrosion current density (i_corr) of 3.72 µA/cm² and a more noble corrosion potential (E_corr) of −743 mV compared to SCE. The improvement mechanism is that the homogeneity induced by complete austenitization minimizes the formation of internal galvanic cells between phases; likewise, the higher austenite fraction provides superior chemical stability, which favors denser passivation. Finally, Route A exhibited the lowest loss of electrical conductivity (16%), validating the use of eddy currents for monitoring the integrity of advanced steels. Full article

The measurement of a probe impedance performed during eddy current inspections enables detection of flaws in electrically conductive materials. A correct interpretation of the measured impedance values constitutes a key aspect that determines the effectiveness of the inspections, and for this purpose, mathematical models are employed. Such models, which are becoming more and more frequently an integral part of eddy current measurement systems, enable carrying out the calculation of the probe impedance, through depicting the measurements being performed. What offer the shortest calculation time while maintaining high accuracy are analytical solutions. In this paper, to the best of the authors’ knowledge, this is the first time an analytical model of an eddy current probe placed over a small diameter cylinder containing a hole has been presented. The final formulas were obtained using the truncated region eigenfunction expansion (TREE) method, and then implemented in Matlab. The calculated values of the probe resistance and reactance were compared with the measurement results obtained for cylinders with a through defect. The tests were conducted on components made of several conductive materials with different geometric dimensions. The measurement error in all of the tests was small, i.e., it did not exceed 3% across the entire frequency range. The proposed solution can be used in defectoscopy for eddy current testing of tubes, pucks, washers, and any cylindrical elements. Full article

Identifying corrosion-prone conditions early is a major maintenance challenge in closed, hard-to-access structural zones. This paper reports an in-service validation of the first monitoring layer of a multi-sensor data fusion approach for early warning of such conditions in selected closed zones of a medical rescue aircraft. The work covers sensor selection, installation in restricted-access compartments, and analysis of data from helicopter operations. Environmental, conductance, and electrochemical channels are combined to identify persistent conditions favorable to long-term corrosion development and to assign warning levels linked to maintenance actions. The thresholds proposed here are empirical screening criteria from the 82-day campaign, not universal damage thresholds or proof of existing corrosion. PZT and eddy-current sensing are planned as follow-up diagnostic layers in the overall architecture. These technologies have been validated separately under laboratory or controlled conditions but were not installed on the flying helicopter during this initial period. Although persistent severe early-warning episodes were detected, they did not coincide with an approved maintenance-access window suitable for additional PZT/EC hardware installation. The present results therefore characterize the corrosion-prone environment and the likelihood of corrosion initiation, not the type, exact location, pit depth, mass loss, or crack initiation of actual damage. Field inspection evidence of corrosion in hidden zones supports the practical relevance of early warning, while full end-to-end validation of localization and damage-growth monitoring remains future work. Full article

High-speed permanent magnet synchronous motors (PMSMs) used in electric pump-fed liquid rocket engines require stator shielding sleeves to prevent corrosive propellants from causing harm under cyclic pressure. However, metallic sleeves suffer significant losses due to eddy currents. Conversely, pure carbon fiber reinforced polymer (CFRP) sleeves have failed when exposed to 98% H₂O₂. Micro-CT analysis of a failed pump sleeve reveals a four-stage failure mechanism. Manufacturing defects caused matrix cracking, which propagated under pressure and thermal cycling. This progression resulted in the formation of through-thickness leakage paths, which ultimately triggered catalytic decomposition and explosion. To address these issues, an improved dual-layer sleeve is proposed, featuring a 2.5 mm PEEK 450G liner and a 2.0 mm T700S/epoxy CFRP overwrap. Finite Element Analysis (FEA) indicates peak von-Mises stresses of 86.25 MPa and 112.16 MPa, yielding Tsai–Wu safety factors of 2.9 and 1.7. Furthermore, various tests, including immersion, fatigue, burst, hydraulic, and thermal evaluations, demonstrate a burst margin of 2.37× at 7.12 MPa, with only 0.19% increase in mass. This design effectively eliminates leakage pathways while preserving zero eddy-current loss and ensuring a low weight. Full article

To address the insufficient damping and instability tendency of metal coil spring isolators subjected to intense impact loading, a multi-stage vibration isolation configuration integrating polyurethane, springs, and eddy current dampers is proposed. Dynamic models for both single-stage and multi-stage isolation systems are formulated, and a corresponding simulation model is developed in MATLAB R2023b/Simulink to investigate the peak suppression and attenuation characteristics of the multi-stage isolation under impact. To characterize the nonlinear finite deformation and time-dependent response of polyurethane, a hyperelastic-viscoelastic constitutive model is established by coupling the Ogden hyperelastic model with a generalized Maxwell viscoelastic model, with model parameters identified through quasi-static compression and stress relaxation tests. Drop impact experiments are performed to compare the displacement response, top- and bottom-plate peak accelerations, and vibration isolation rate between a polyurethane-spring-eddy-current multi-stage isolator and a spring-spring-eddy-current multi-stage isolator. The results demonstrate that the multi-stage structure enables staged dissipation of the impact energy, substantially reducing both the peak acceleration and the displacement stroke of the isolated mass. Under all drop test conditions, the polyurethane-based multi-stage isolator yields lower top-plate output peak acceleration and higher isolation rate than its all-spring counterpart, confirming its superior isolation performance. Envelope fitting of the simulation-based output acceleration with experimental inputs reveals that the all-spring multi-stage isolator exhibits a higher attenuation rate and equivalent damping ratio, whereas the polyurethane-based isolator achieves more effective suppression of the output peak level under severe impact conditions. Full article

Morse-type tapers at the head–stem junction in total hip replacements (THRs) provide many benefits to permit a successful surgical outcome. However, with the introduction of modular tapered devices comes complications associated with fluid ingress and motion at the interface that can cause fretting corrosion, which has been implicated in clinical failure. Increased surface roughness amplitude (R_a) and angular mismatch to ensure taper contact closer to the equator of the femoral head are design features introduced for use with ceramic heads but have been adopted by metal head couples. While increased surface roughness amplitude has been found to contribute to fretting corrosion, there is a distinct lack of systematic studies investigating the interactions between angular mismatch and R_a. This study measured the fretting corrosion and motion response of clinically representative samples, in part reference to ASTM F1875, when subjected to uniaxial incremental dynamic loading. The fretting corrosion response was measured in situ with an integrated three electrode electrochemical cell. Motion at the head–neck interface was measured with a bespoke motion measurement solution based on eddy-current principles which uses four sensors to allow motion to be fully characterised in three dimensions. Key findings from this study included a 5–10-fold increase in current measured in the increased roughness amplitude samples, suggesting an increased susceptibility to fretting corrosion without a corresponding increase in motion. The distal samples engaged around the opening of the taper interface and presented the lowest current measurements but most off-axis subsidence. Findings from this study indicate that optimisation of the taper interfaces in THR, in terms of fretting corrosion and motion, can be made and can be assessed using short-term preclinical tests. Full article

The aim of this review is to clarify the mechanism and influencing factors of flow-assisted corrosion in multi-medium transmission pipelines for pipeline safety management, along with the progress in nondestructive testing in this vein. Such pipelines undergo severe flow-assisted corrosion under multiphase-flow, high-temperature, high-pressure, and complex chemical conditions, threatening structural integrity and operational safety. This study summarizes the dominating roles of aqueous wetting, mass transfer, and flow-induced shear stress in corrosion evolution and analyzes the coupling effects of hydrodynamics, medium chemistry, and material properties on corrosion deterioration. The applicational advantages and limitations of ultrasonic guided-wave, magnetic flux leakage, and eddy current testing in corrosion detection are systematically concluded. Future development trends combining artificial intelligence, machine learning, and digital twins are projected, providing a reference for intelligent detection and full-life-cycle integrity management of transmission pipelines. Full article