SiC particles-reinforced aluminum matrix (SiCp/Al) composites have been widely used in aerospace science and engineering fields. Nevertheless, the evolution of mechanical properties and deformation behaviors at cryogenic temperatures remains unclear, which still limits their manufacturing process and applications. In this paper, indentation responses of SiCp/Al composites were systematically investigated using instrumented grid indentation at room and cryogenic temperatures. According to the image processing technology of microstructure and statistical analysis of multi-modal Gaussian distribution functions, a novel method is developed that accounts for both particle properties and grid indentation spacing. Additionally, this work reveals a remarkable effect of the cryogenic environment on micromechanical properties and deformation behaviors during indentation. The results indicate that the elastic moduli increase by 12.67 % for SiC particles and 55.22 % for the 6092 aluminum matrix with the temperature decreasing from room temperature to -150 degrees C. The composites exhibit remarkable weakness in wear resistance below -100 degrees C, which is mainly attributed to the coupling effect of thermal contraction mismatch (similar to 0.00245) and indentation-induced reaction stress for SiCp/Al composites. This work may provide more in-depth thoughts on the evolution of micromechanical properties at cryogenic temperatures.

In situ indentation/scratch testing technique is a crucial method for analyzing material mechanics and damage evolution. However, conventional instruments suffer from limitations such as low load capacity and destructive backward motion. In this study, an in-situ indentation/scratch instrument coupled with scanning electron microscope was developed. Hybrid motor-piezoelectric actuation was designed, enabling ultra-long stroke loading and unloading free from mechanical backlash. The compact design incorporates a motor-driven XY stage with 40.5 mm Z-height, maintaining high load capacity while eliminating backlash errors. Integrated PID control, high-ratio reducers, and encoders achieve 10 nm s-1-80 & micro;m s-1 stepless motion with precise XYZ positioning, accommodating both coarse alignment and fine loading. Following calibration, functional tests were conducted on brittle monocrystalline silicon, Q235 steel, and galvanized coatings. The instrument captured crack initiation in silicon under hundred-millinewton loads and correlated subsurface/surface slip in coatings via deep indentation (54 mu m). Indentation and backward-free scratch tests on Q235, along with mechanical properties derived from load-displacement curves, demonstrate the equipment's precise testing capability and high data reliability across a broad load range and diverse material systems.

Al-Ce alloys hold considerable promise for lightweight structural applications owing to the excellent thermal stability of the AlCe3 intermetallic phase. However, their industrial adoption is constrained by the inherently low ductility arising from the continuous network-like brittle eutectic structure in the as-cast condition. This study systematically investigates the multi-scale regulatory mechanisms by which Mg alloying and Zr/Sc microalloying govern the microstructural evolution and room-temperature mechanical properties of Al-Ce-based alloys. The results demonstrate that Mg addition effectively fragments the continuous brittle eutectic network into a dispersed particulate morphology, thereby optimizing stress distribution during deformation and suppressing intergranular crack propagation. With increasing Mg content, the ultimate tensile strength initially increases and then decreases, while the elongation decreases monotonically from 5.0

This study systematically investigates the effects of indenter direction (edge-forward vs. face-forward) and crystal orientation ([2110] a- vs. [0110] m-orientation) on the mechanical response and damage evolution of GaN (0001) surfaces during scratching through a combination of experiments and molecular dynamics (MD) simulations. The results reveal significant anisotropy in the coefficient of friction (COF): the COF in the a-orientation is approximately 5% higher than that in the m-orientation, which is attributed to the formation of a more complex dislocation network. High-resolution transmission electron microscopy (TEM) confirms that the { 2112} < 1213 > pyramidal slip system, with a characteristic angle of similar to 55 degrees, dominates the plastic deformation. Additionally, a stress-induced phase transition from wurtzite to zinc blende is observed within the scratch-damaged layer. Through stress field analysis, the initiation and propagation mechanisms of radial, median, and lateral cracks are elucidated. MD simulations further reveal the anisotropy of dislocation motion and its influence on frictional force at the atomic scale. These results provide multiscale insight into anisotropic deformation in GaN and offer guidance for optimizing low-damage precision processing.

The impact resistance of aluminum alloys critically influences the service reliability of key load-bearing components in aerospace and automotive industries. However, the unclear micro-failure mechanisms under high-velocity impact loads severely limit lifespan improvements. This study developed a compact desktop-level electromagnetic ejection-based high-velocity impact in-situ testing system through systematic optimization of excitation current parameters, coil geometry, and multi-stage configuration. The system integrates a nine-stage electromagnetic coil acceleration module achieving 62 m/s impact velocity and an in-situ monitoring unit combining infrared thermography, high-speed imaging, and acoustic emission signal. Multi-angle impact experiments enabled synchronized monitoring of dynamic mechanical responses, micro-damage evolution, and transient temperature fields. Experimental results demonstrate that increased impact angles reduce impact load, shift plastic flow from radial uniformity to shear dominance, expand transient thermal zones, and transition acoustic emission signatures from low-frequency plasticity to shear-induced frequencies.

Zn-based alloy coatings are widely applied in surface mechanical protection due to their superior properties. However, the deformation mechanisms at interlayer and interfacial regions under localized mechanical loading remain poorly understood due to technical limitations, hindering performance optimization. In this study, hot-dipped Zn-Fe alloy coatings, an essential Zn-based alloy coating system, were investigated using a novel in-situ indentation technique combined with scanning electron microscopy to directly characterize subsurface deformation during indentation. The results showed that the zinc layer (η) and the mixed layer of zinc and zinc-iron compound FeZn13 (ζ1), with lower iron content, underwent plastic deformation without cracking. In contrast, the layer of zinc-iron compound FeZn13 (ζ2) and the layer of zinc-iron compound FeZn10 (δ), with higher iron content, exhibited significant crack formation and fracture. The intergranular cracks in the δ layer propagated to the interface, causing discontinuous fractures at the interface. These discontinuities and cracks mutually accelerated, resulting in rapid and catastrophic coating failure.

Curved surface components (CSC) are increasingly utilized in aerospace, high-speed transportation, and advanced equipment sectors, where their operational safety critically depends on the high-precision nondestructive evaluation (NDE) of key structural components. Flexible phased array ultrasonic testing, owing to its superior surface conformity, offers significant advantages for defect detection in geometrically complex components. However, existing acoustic field models are predominantly formulated along the transducer centerline, making them inadequate for inspection scenarios involving complex structures with variable curvature. To address the demand for efficient inspection of curved components, this study establishes a systematic focusing algorithm framework for multilayer structures with variable curvature, using the initial element of the flexible transducer array as a reference. A multi-line source acoustic field model is further proposed to enable efficient and accurate field simulation for flexible array transducers. The proposed models are validated through numerical simulations in both time and frequency domains, and the focal performance of ultrasonic wave under different curvature conditions is further examined. Furthermore, the flexible phased array inspection system is implemented to evaluate flat-bottom hole and artificial crack defects in multiple curved specimens. The results demonstrate that the proposed method achieves accurate detection of cracks as small as 0.2 mm x 0.5 mm and delivers high-resolution imaging even under double-layer curved conditions. It validates the practical applicability and scalability of the proposed approach for advanced NDE of complex structural components.

Abstract The wear condition of the roller surface on the roll-forming end effector significantly affects the quality of automotive body molds and the service life of the corresponding equipment. To address these issues, this study proposes a biomimetic roller design strategy based on the microstructure of the pearl shell surface. A corresponding texture-morphology mapping model was established, followed by multi-scale mechanical and tribological performance analysis. Simulation results indicate that, under the same depth-to-width ratio conditions, the roller with arcuate grooves exhibits the lowest friction energy loss and the highest principal stress compared to rollers with vertical and rhombic grooves. Friction wear tests further validate the advantages of this structure, showing significantly lower coefficients of friction, wear depth, and wear mass than those of rollers with vertical and rhombic textures, demonstrating superior wear resistance. Based on this, the depth-to-width ratio structure of the arcuate striped roller was further optimized using the golden section method, determines a global optimal depth-to-width ratio of 0.775. Compared to ordinary rollers, the maximum principal stress along the rolling direction increased by 18.3% for the optimized roller, while rolling friction energy decreased by 70.28%. This study demonstrates that biomimetic textures can significantly improve the surface stress distribution and tribological performance of rollers, provide theoretical support and innovative solutions for enhancing the stability of automotive body manufacturing processes and the reliability of intelligent devices.

In the field of architecture, notches inevitably emerge in Laminated Bamboo (LB) beams due to factors such as processing techniques and service environments. Such defects significantly undermine their load-bearing capacity, posing potential threats to structural safety. However, since research on the impact of notches on the mechanical properties of LB is still in its infancy, a systematic understanding of the underlying mechanisms has not been established, and the quantitative relationship between notch parameters and mechanical performance remains unclear. Given this, this study explores the coupled influence mechanisms of notch depth ( h n , with values of 2 mm, 4 mm, 6 mm, and 8 mm) and notch location ( L d , with values of 0 mm, 15 mm, 30 mm, 45 mm, 60 mm, 75 mm, and 90 mm) on the bending performance and failure modes of LB beams. Experimental results indicate that the bending performance of LB beams deteriorates significantly with increasing h n and decreasing L d . Moreover, the adverse impact of notches on strength is notably more pronounced than that on stiffness. Based on the experimental data, a quantitative predictive model for the strength/stiffness reduction factors of notched LB beams has been developed. Further analysis using Digital Image Correlation (DIC) and Scanning Electron Microscopy (SEM) reveals that specimens with offset notches exhibit a composite failure mode characterized by longitudinal splitting and localized delamination fracture. Among these, longitudinal splitting is triggered by the synergistic effect of shear and transverse strains, representing a mixed-mode (I-II) fracture. This study provides a theoretical basis for understanding the bending mechanical response of notched LB beams and offers technical support for their optimized structural design, defect tolerance assessment, and safety analysis in engineering applications. It holds significant academic value and practical implications for advancing the engineering application of bamboo-based structural materials.

It is crucial to monitor the real-time and accurate status of an electric drive system and understand its interaction with driving behavior in order to meet the higher requirements for vehicle safety and reliability in the era of autonomous driving. Traditional wired sensors have limitations in system integration and energy autonomy. This study proposes a triboelectric nanogenerator (TENG) based on the centrifugal-force-enhanced contact mechanism, which can be directly integrated into the transmission shaft of electric vehicles to construct an intelligent self-powered monitoring system. This design effectively overcomes the bottleneck of unstable signals and insufficient durability of traditional rotating TENGs at high speeds by coupling centrifugal force and spring pre-tension and outputs stable and high signal-to-noise ratio sensing signals. On this basis, this study not only achieved high-precision real-time perception of the driving system speed but also further explored the rich information embedded in the centrifugal-force-enhanced contact TENG signal and extended it to the intelligent recognition of driving behavior and road conditions. Based on signal processing and the convolutional neural network and bidirectional long short-term memory model, the system has achieved fault diagnosis of key transmission component bearings in the transmission system with an accuracy rate of up to 96.1%. At the same time, the system can effectively recognize driving behaviors such as sudden acceleration and deceleration (recognition accuracy of 84%), as well as typical road conditions such as flat, slippery, and speed bumps (recognition accuracy of 89.9%), providing key information for automatic driving algorithm calibration and driving safety improvement. The self-powered embedded sensing technology developed in this study provides a new technological path for the efficient energy management and predictive maintenance system of intelligent connected vehicles and is a key sensing node for building future autonomous transportation systems.

Environmental vibration energy, as a widely available renewable source, presents a promising solution for powering low-consumption electronics like wireless sensor networks and internet of things nodes. While piezoelectric cantilever energy harvesters have been extensively studied, their inherently narrow bandwidth remains a major obstacle to their practicality in random vibration environments. Although introducing magnetic nonlinearity has proven effective for bandwidth broadening, a systematic comparison of the performance and intrinsic mechanisms of different basic magnetic configurations under uniform benchmarks is still lacking. This paper presents a systematic comparative study of four magnetically coupled nonlinear configurations for broadband vibration energy harvesting through integrated theoretical modeling and experimental validation. A distributed-parameter magneto-electro-mechanical coupling model was established, which successfully predicts the output voltage and bandwidth characteristics of each nonlinear configuration. The influences of magnet spacing, excitation level, and frequency sweep direction on system performance were thoroughly investigated via experimental tests and simulation analysis. The results reveal several key findings: first, multistable configurations demonstrate significant advantages in bandwidth broadening. The double-magnet attractive configuration, forming an ideal tristable potential energy distribution at specific parameters, achieves an effective bandwidth of 7.38 Hz and a peak-to-peak voltage of 181.45 V under forward frequency sweep, outperforming the optimal bistable configuration's bandwidth of 6.72 Hz. Second, the system performance exhibits strong sweep-direction dependence. The double-magnet repulsive configuration under specific parameters in a reverse frequency sweep achieves an ultra-wide effective bandwidth of 10.99 Hz, while maintaining a peak-to-peak voltage of 143.31 V. Furthermore, the study identifies precise optimal ranges for the magnetic parameters, with any deviation leading to significant performance degradation. Through the mutual verification of theoretical prediction, numerical simulation, and experimental measurement, this study provides the first systematic performance comparison of four typical nonlinear magnetic configurations under a unified benchmark. The results clarify the advantages and design principles of multistable nonlinear mechanisms for achieving high-performance broadband energy harvesting, offering critical guidance for optimizing vibration energy harvesters in practical applications.

This study examines the mechanical behaviour of particle-reinforced composite materials (PRCMs) under micro and nano-indentation using FEM simulations. Particular attention is given to deep indentation, where the contact between the indenter and reinforcing particles plays a more prominent role. To address this, a new approach is introduced to estimate the elastic modulus of individual particles based on energy decomposition combined with a segmented fitting strategy, allowing local mechanical properties to be evaluated without causing damage. FEM simulations, together with experimental validation, are used to analyse how particle distribution, matrix properties, and residual stresses influence the indentation response. The results show that, unlike homogeneous materials, PRCMs exhibit more complex indentation behaviour due to the significant effect of particles on local stiffness and hardness. Even under complex loading conditions, the proposed method provides reliable modulus extraction, offering practical guidance for the mechanical characterisation and design optimisation of composite materials.

Optimizing the yield ratio and ductility is essential for improving mechanical adaptability and structural reliability in applications spanning biomedical devices, aerospace structures, and flexible electronics. In this study, AlFeCrNiV high-entropy alloys (HEAs) were fabricated via laser powder bed fusion (LPBF), and the effects of substrate temperature (348 and 573 K) and subsequent aging time (6, 12, 48, and 120 h) on microstructural evolution and tensile properties were systematically investigated. The 348 K-fabricated alloy exhibited finer grains, higher residual stress, and greater dislocation density than that 573 K-fabricated, resulting in higher yield strength (YS=680.2 MPa) and ultimate tensile strength (UTS=902.7 MPa), but lower total elongation to failure (30.5 %). During aging, the 348 K series developed a higher volume fraction of BCC precipitates. After 120 h of aging, the 348 K-fabricated alloy maintained a high UTS (920.8 MPa), while its YS decreased to 474 MPa and elongation increased to 36.2 %, thus achieving a desirable combination of a low yield ratio and improved ductility. In-situ EBSD tensile testing and TEM analysis revealed that finely BCC precipitates act as effective barriers to dislocation motion, promote dislocation storage and multiplication, and significantly improve strain-hardening capability. Additionally, these precipitates induce localized lattice rotation and facilitate the formation of refined subgrain-scale deformation-coordination units, effectively suppressing strain localization. The concurrent reduction in yield ratio and improvement in ductility is thus achieved through the synergistic regulation of dislocation density and BCC precipitation. This study elucidates the intrinsic process-microstructure-property relationships in LPBF-fabricated HEAs and provides a framework for microstructure-driven mechanical optimization.

With advances in bamboo processing technology, it has become possible to retain and utilize bamboo cortex (BC) and bamboo pith ring (BPR). However, the mechanisms by which BC and BPR influence the anisotropic bending behavior of bamboo have not been fully elucidated. This study combined micro-computed tomography (micro-CT), scanning electron microscopy (SEM), and digital image correlation (DIC) techniques to investigate the effects of BC and BPR on the anisotropic bending properties of bamboo in the longitudinal and tangential directions. The experimental results showed that the longitudinal bending properties of bamboo, including strength, modulus, toughness, and ultimate strain, were significantly superior to those in the tangential direction. BPR showed a detrimental effect in the longitudinal direction but a beneficial one in the tangential direction. In situ DIC tests showed that BC and BPR had no significant effect on the fracture behavior in the tangential direction. In contrast, under longitudinal bending, removal of BPR delayed crack initiation, whereas removal of BC accelerated failure and suppressed toughening mechanisms. SEM fracture surface analysis showed that longitudinal bending exhibited ductile fracture characterized . This study provides a theoretical basis and experimental support for the refined processing and high-performance structural design of bamboo.

Welding is widely used for large-scale structural components such as high-speed rail carriages and ship hulls, but the resulting weld bead protrusion induces stress concentration and fatigue cracking. Robotic belt grinding offers a flexible solution for weld finishing. However, under constant process parameters, uneven weld height leads to a significant deviation between actual and theoretical removal depth, resulting in poor surface consistency. In order to solve the above problems, a new method for adaptive optimization of robot weld grinding speed based on weld allowance height feature matching is proposed. The weld morphology is rapidly acquired using laser vision sensing, and Gaussian process regression is introduced to accurately extract weld height under base metal deformation. A multi-scale material removal depth model is then established by integrating microscopic abrasive grain mechanics with macroscopic contact mechanics, revealing the quantitative mapping relationship between weld height and feed rate. A closed-loop "perception-modeling-control" architecture is constructed to enable real-time speed optimisation, where the feed rate is adaptively reduced in regions with large residual height and increased where residual height is small. Comparative grinding experiments on straight, broken-line, and curved welds demonstrate that the proposed method achieves an average residual height of 0.16 mm, a standard deviation of 0.015 mm, and a surface roughness Ra of 0.343 mu m. Compared with constant-speed grinding, the height variation is reduced by 91%, and the surface roughness is improved by over 50%. This study provides a novel approach for high-quality, controllable robotic weld grinding.

As a primary material for aircraft fuselage panels, glass fiber-reinforced aluminum laminates (GLARE) are frequently subjected to combined tension-torsion (CTT) loading and ambient temperatures during service, leading to complex failure mechanisms. To reveal the mechanical response and evolution of failure modes under such service conditions, this study systematically investigates the effect of ambient temperature on the mechanical behavior of GLARE laminates under CTT loading. The results indicate that the mechanical properties of the material degrade with increasing temperature, and this degradation becomes more significant with a larger pretorsion (PTO) angle. For instance, at a PTO angle of 45 degrees, a temperature rise from -55 degrees C to 80 degrees C leads to substantial reductions in ultimate strength (sigma max), failure strain (epsilon max), elastic. modulus (E), and energy dissipation capacity (Wd). Notably, the degradation exhibits a clear temperature dependence: at low temperatures (e.g., -55 degrees C), PTO has a slight effect on mechanical properties, whereas at elevated temperatures, the degradation effect is significantly enhanced. Based on scanning electron microscopy (SEM) fractographic morphology, the evolution of failure modes under different conditions is further analyzed, and a failure map under CTT loading is established. At low temperatures, the resin matrix exhibits brittleness and sensitivity to PTO damage, leading to brittle fracture. At high temperatures, matrix softening reduces brittleness but simultaneously weakens interfacial bonding, leading to a trade-off: tunnel cracks are suppressed, but premature delamination and reduced load transfer efficiency occur, particularly under off-axis loading induced by PTO. This paper provides important experimental data and theoretical support for the multi-factor reliability evaluation and damage-tolerant design of GLARE laminates in aerospace structures.

Laminated metal composites (LMCs) exhibit significant potential in fields such as aerospace and armor protection, yet their dynamic deformation mechanisms remain inadequately understood. To address this, titanium-aluminum LMCs were fabricated from pure Ti (TA1) and Al (1060) foils via diffusion bonding. Their dynamic deformation and energy dissipation were investigated using a custom high-strain-rate (103/s) impact apparatus, high-speed DIC, and infrared thermography. Results show the LMC's impact depth was 6 %-15 % lower than the rule-of-mixtures (ROM) prediction. At the highest impact velocity (467.3 mm/s), energy absorption efficiency increased by 6.5 % and dynamic elastic modulus exceeded ROM by 3.4 %. High-speed DIC revealed the Ti layer confined near-surface plastic deformation via strain interception, while the Al layer accommodated interlayer differences through concentrated plastic flow. This synergy shifted the deformation mode from "sink-in" to "pileup". An "elbow" feature in the unloading curve indicated preserved elastic recovery in the Ti layer. This multi-scale study elucidates the micromechanical synergy enhancing LMC impact resistance, providing important insights for aerospace and protective material design.

Layered metal composites (LMCs) are promising for structural applications, yet systematic investigations into their impact toughness remain limited. In this study, Ti-Al LMC was fabricated via hot-press diffusion bonding. Their impact toughness was quantified using a custom-developed in-situ impact testing platform and compared with their monolithic constituents. The LMCs exhibited an impact toughness more than double that of the constituent metals, demonstrating enhanced ductility and preventing macroscopic brittle fracture. Advanced insitu techniques, including high-speed imaging and infrared thermography, were employed to capture the dynamic deformation morphologies, strain evolution, and thermal responses during impact. The results reveal that the laminated architecture, coupled with the mechanical property mismatch between layers, is associated with an effective negative Poisson's ratio phenomenon. This effect promotes strain homogenization during deformation, which enhances the composite's ductility and triggers a distributed, multi-point damage mode instead of localized failure. Consequently, this strain homogenization also leads to homogenized strain rates and thermal fields. The peak temperature rise in the Ti layers of the LMC was reduced by over 100 degrees C compared to monolithic Ti, effectively contributing to a reduced risk of potential failure. This work provides a new mechanistic understanding and a design paradigm for developing advanced composites with enhanced impact resistance.