To quantify the formation and spatial expansion of wear zones on a ploughshare under different tillage parameters, in this study, a soil‒ploughshare interaction model is established in EDEM 2024 using the discrete element method coupled with the Archard wear model. The effects of tillage speed, tillage depth, and penetration angle on ploughshare force, power consumption and high-wear area distribution are investigated. In accordance with the curved geometry of the ploughshare surface and the soil contact path, the working surface is divided into a cutting zone, a bearing zone, and a diversion zone. The overall and zonal proportions of the high-wear area are extracted, and the time-averaged high-wear area proportion, zonal expansion coefficient and wear area development index (WADI) are constructed. The results show that ploughshare wear is characterized by clear accumulation over time and spatial nonuniformity. The high-wear area first appears near the lower cutting edge and the front lower contact region and then expands towards the middle working surface along the sliding direction of the soil particles. When the tillage speed increases from 1.25 to 2.00 m/s, the overall high-wear area proportion increases from 6.00% to 26.14%, whereas that in the bearing zone increases from 2.55% to 33.19%. When the tillage depth increases from 125 to 200 mm, the overall high-wear area proportion increases from 15.23% to 45.12%, and that in the diversion zone increases from 0.30% to 14.46%, indicating that deep tillage promotes upwards wear expansion. When the penetration angle increases from 30° to 75°, the overall high-wear area proportion decreases from 26.14% to 3.03%, although the relative fluctuation of the load increases. Tillage speed mainly promotes wear expansion by increasing the particle sliding velocity and scouring frequency. Tillage depth increases the wear range by increasing the soil contact volume and contact area. Furthermore, the penetration angle suppresses the development of high-wear areas by changing the contact characteristics and soil flow path. The proposed zonal quantification method involves converting the spatial information in Archard wear contour maps into comparable indices, providing a basis for identifying critical wear zones, optimizing wear-resistant structures, and matching tillage parameters.
Cross-material continuous tool wear prediction is difficult because a model must preserve the physical wear scale, not only align high-dimensional sensor features. This limitation is critical in milling, where the target variable is the continuous flank wear width (VB) and material shift can distort the mapping from sensor response to wear magnitude. We address this problem by recasting cross-domain tool wear prediction as monotone wear-scale adaptation. We propose Multi-Physics Monotone Score Transport (MPMST), a monotone score transport framework that constructs a tool-wear-oriented score from sensor-derived candidate cues, transports the target-domain score onto the source-domain wear scale, and then predicts wear through isotonic regression. We also evaluate One-Physics Monotone Score Transport (OPMST), a force-only variant that uses the same score-transport pipeline with a restricted cue family. On Mondragon Unibertsitatea-Tool Condition Monitoring (MU-TCM) with two cross-material transfer tasks, the validation-driven MPMST configuration reduces mean absolute error by approximately 63% relative to Correlation Alignment (CORAL) and by approximately 31% relative to a physics-informed Gaussian process baseline. The results support monotone score construction and score transport as practical mechanisms for continuous tool wear prediction under domain shift, while also showing that MU-TCM is strongly force dominated.
High-speed press systems operate under severe dynamic loading conditions, where bushing components are subject to accelerated wear that directly affects system reliability and maintenance cost. Despite extensive studies on bearing wear in automotive and aerospace applications, wear behavior under high-speed press conditions remains insufficiently explored. This study proposes a wear prediction model that integrates experimental measurements with finite element analysis (FEA). A key hypothesis is that bushing wear under high-speed press conditions can be accurately described by an extended Archard wear model incorporating contact pressure distribution and shaft misalignment effects. A controlled experimental setup was developed to replicate real operating conditions. Wear profiles were measured using high-resolution profilometry, while corresponding contact pressure distributions were obtained via 3D FEA simulations. Model parameters were calibrated using a subset of experimental data and validated against independent test cases. The proposed model demonstrates strong predictive capability, achieving an RMSE of 0.98 μm and an MAE of 0.57 μm across the 30-min calibration cases under the average (AVG) load-cell calibration. The extended formulation captures the asymmetric wear patterns induced by misalignment and resolves the high-pressure peak underestimation observed in the plain Archard baseline.
Aluminum alloy (AA) 2024-T3 is widely used in the aerospace industry due to its high specific strength and superior fatigue resistance, yet its moderate hardness and inadequate wear resistance fail to meet service demands under severe wear conditions. Although the electropulsing-assisted ultrasonic surface rolling process (EP-USRP) can strengthen its surface, the mechanism by which pulsed current density influences the friction and wear properties of the strengthened layer remains unclear. This study employed EP-USRP to strengthen the surface properties of AA 2024-T3, systematically examining the impacts of different pulsed current densities on its surface morphology, roughness, microhardness, and tribological performance, while comparing wear mechanisms among differently treated samples under various normal loads. The results indicate that EP-USRP can improve the surface mechanical properties compared with USRP. At 1.42 A/mm2 current density, the EP-USRP-3 sample achieved 27.7% lower surface roughness and 19.6% higher microhardness. Under a 2 N normal load, its average friction coefficient, wear volume, and wear rate decreased by 5.34%, 36.28%, and 36.27%, respectively. Adhesive and oxidative wear, coupled with material spalling, constitute its main wear behavior. The electroplastic effect induced by pulsed current may facilitate the increase in strain levels and dislocation densities, which could contribute to the improved surface mechanical and tribological properties of AA 2024-T3.
The long-term stability of biomedical hard-tissue implants is closely associated with the homeostasis of the surrounding immune microenvironment. Wear particles generated from implants can trigger immune activation, leading to local inflammatory responses and inducing bone destruction, ultimately resulting in implant failure. In addition, in patients with diabetes, chronic metabolic disturbances can disrupt immune homeostasis around implants, thereby increasing the risk of implant-related complications. Although the immunological effects of wear particles under normal physiological conditions have been extensively studied, their behavioral characteristics and immunological effects under metabolic disorder conditions such as diabetes remain insufficiently elucidated. Previous studies have demonstrated that nanoparticles rapidly acquire a protein corona (PC) upon exposure to biological fluids, which determines their immune recognition and interactions with cells. However, how diabetes-associated metabolic abnormalities remodel the PC on wear particles and thereby modulate immune responses has not been fully elucidated. In this study, we found that diabetes induces the formation of a distinct PC, referred to as DM-PC (Diabetic-derived protein corona). The DM-PC was enriched in receptor signaling-related proteins, enhancing interactions between wear particles and macrophage membrane receptors and activating the downstream JAK1-STAT3 pathway. The resulting immune imbalance significantly enhanced particle-induced M1 polarization and osteoclast activation. Collectively, this study proposes a mechanism by which the DM-PC modulates macrophage recognition of wear particles and enhances their inflammatory effects through an inflammation-amplifying signaling axis. These findings provide insight into how diabetes-associated metabolic dysregulation drives the progression of implant complications and offer potential intervention targets for improving the long-term stability of hard-tissue implants in the context of metabolic diseases. STATEMENT OF SIGNIFICANCE: Although the immunological effects of wear particles generated from hard-tissue implants under normal physiological conditions have been extensively investigated, their behavioral characteristics and biological effects in the context of metabolic disorders such as diabetes remain insufficiently elucidated. Given this, from the perspective of the protein corona, this study demonstrates that the diabetic microenvironment alters the interfacial biological properties of wear particles and reshapes their interactions with macrophages, thereby exacerbating inflammatory responses and bone destruction. This study not only elucidates the potential biological basis underlying the increased risk of hard-tissue implant-related complications in patients with diabetes and provides mechanistic rationale as well as potential strategies for the prevention or intervention of implant-related complications in diabetic individuals.
Accurate measurement of the temperature in the cutting zone is essential for closed-loop machining. However, it remains difficult due to the small size of the tool-chip contact area, its partial concealment by chips and the steep thermal gradients present. This study presents an integrated framework that combines a thin-film thermocouple (TFTC) on the rake face of a polycrystalline cubic boron nitride (PCBN) tool with a thermo-mechanical wear-coupled simulation in order to monitor cutting temperature and predict tool wear. The three-dimensional finite-element turning model includes a moving heat source that represents plastic and frictional heat at the tool-chip interface, as well as an Archard-type wear law that is enhanced by a temperature correction factor. The TFTC is fabricated by magnetron sputtering NiCr and NiSi films onto an insulating layer, after which it is embedded in the tool as a minimally intrusive in situ sensor. Turning experiments on AISI 1045 steel were performed at spindle speeds of 1000-3000 rpm, feeds of 0.05-0.20 mm/rev and depths of cut ranging from 0.3 to 1.0 mm under dry, wet (emulsion) and cryogenic (liquid nitrogen) cooling conditions. Simulated temperature fields reveal strong localisation at the tool-chip contact and a nonlinear increase in peak rake-face temperature with spindle speed, which fits a quadratic regression with R2 = 0.99. The TFTC shows a response time of around 0.3 s with less than 5% overshoot, and its thermoelectric voltage is almost perfectly linear with temperature (R2 = 1), with a sensitivity of approximately 12 µV/°C. During cutting, TFTC readings agree with infrared measurements within ±3 °C and demonstrate improved robustness in occluded zones. The coupled wear model replicates the observed wear growth trend with the compact expression VB = 0.0001·t0.8. Sensitivity tests indicate that thermo-mechanical coupling increases wear rates compared to single-factor models, and that cooling reduces thermal loads by approximately 15% (wet) and 25% (cryogenic).
In the existing tool wear status monitoring process, the difference in the distribution of tool wear signal characteristics under different processing conditions leads to insufficient generalization of the model and poor accuracy of wear status recognition. Aiming at the problem, a method for monitoring the wear status of milling cutters under variable working conditions based on transfer learning and a lightweight SqueezeNet model is proposed. Firstly, the continuous wavelet transform (CWT) is employed to realize the conversion of the raw vibration signal to a time-frequency energy diagram to completely preserve the joint feature distribution of the vibration signal in the time and frequency dimensions. Secondly, based on the phased transfer learning strategy and the lightweight SqueezeNet, a monitoring model of the wear status of the milling cutter under variable working conditions is established, which realizes the adaptive and accurate identification of the wear status of the milling cutter under different milling conditions. Finally, comparative experiments were performed using three groups of vibration signals under different milling condition as the model inputs. As demonstrated by the experimental results, the recognition accuracy of the test set of the proposed monitoring model under variable working conditions can reach 94.583%, which is higher than the 91.133% of the LSTM-DBO-SVM model, which proves the accuracy and feasibility of the presented approach under variable working conditions.
To evaluate risk behaviors for infectious keratitis among contact lens (CL) wearers in Switzerland, focusing on survey-based, observational subgroup analyses by contact lens type. This investigator-initiated, cross-sectional, survey-based, observational, multi-center study was conducted across five eye care institutions in Switzerland. Between August 2023 and August 2024, we interviewed participants wearing CLs using a structured questionnaire. We assigned four subgroups, which included daily disposable soft contact lenses (SCL), reusable SCL, rigid corneal contact lenses (RCL), and rigid scleral contact lenses (ScCL). The survey collected data on demographics, CL type and indication, self-assessed CL knowledge, and risk behaviors related to infectious keratitis. We classified risk behaviors into three main categories, including hand hygiene, wearing behavior, and exposure to water or saliva. 156 participants were included in the final analysis. Regarding the subgroup allocation, 38 of 156 (24.4%) wore daily disposable SCLs, 48 (30.8%) reusable SCLs, 40 (25.6%) RCLs, and 30 (19.2%) ScCLs. Overall, participants wearing rigid CLs felt better informed about CL care and demonstrated fewer risk behaviors than SCL users. However, risk behaviors were observed across all subgroups, including applying or removing lenses with potentially contaminated hands, extended CL wear, sleeping with CLs, and exposure to water or saliva. This study revealed variations in hygiene practices, wearing behavior, exposure to water or saliva, and risk perception across different CL types. Nevertheless, risk factors for infectious keratitis were present among all subgroups, underscoring the need for lens-specific patient education under professional supervision to improve compliance and mitigate complications.
The temperature-dependent wear behavior of a cobalt-based Stellite 6 alloy was investigated from room temperature (RT) to 800 °C using high-temperature reciprocating sliding tests. The friction coefficient decreases monotonically with increasing temperature, from about 0.56 ± 0.12 at RT to 0.26 ± 0.11 at 800 °C, whereas the wear rate exhibits a pronounced non-monotonic evolution. Specifically, the wear rate increases from 18.4 ± 1.5 × 10-6 mm3·N-1·m-1 at RT to a maximum of 54.8 ± 1.6 × 10-6 mm3·N-1·m-1 at 600 °C, followed by an anomalous reduction to 10.2 ± 1.5 × 10-6 mm3·N-1·m-1 at 800 °C, which is even lower than that at RT. Microstructural and elemental analyses indicate that this behavior is governed by the temperature-dependent evolution of oxide layers. At RT-600 °C, thin and mechanically unstable oxide films repeatedly form and fracture, promoting oxidation-assisted abrasive and adhesive wear. In contrast, at 800 °C, a continuous and dense oxide layer forms and acts as a stable tribo-oxide film, effectively suppressing severe material removal. These findings clarify the temperature-driven wear mechanism transition of Stellite 6 alloy under high-temperature sliding conditions.
WC-Co composites are widely applied in various industries due to their high hardness and wear resistance. The addition of zirconia further enhanced the composite, improving grain refinement and reducing the friction coefficient. Zirconia submicron particulate reinforcement strengthened the cobalt binder phase, significantly improving the wear resistance. Tribological tests were performed in ball-on-flat dry sliding mode, against an Al2O3 counter body. The specimen WC-6Co-10ZrO2 exhibited a decrease in volumetric loss ΔV by 66% compared to 94WC-6Co composite, and the wear rates Ws showed a 50% decrease for 4 wt.% zirconia addition and up to 80% when 10 wt.% ZrO2 was added. In tribological tests, a five times larger load, 100 N instead of 20 N, caused an increase in the wear rate 1.1, 1.3, and 1.9 times for WC-Co, WC-6Co-4ZrO2, and WC-6Co-10ZrO2 compositions, respectively. Abrasive and adhesive wear mechanisms were identified.
AlCoCrFeNi high-entropy alloy coatings reinforced with different TiN contents (2 wt.%, 4 wt.%, and 6 wt.%) were fabricated on 304 stainless steel by laser cladding. The effects of TiN addition on the microstructure, hardness, friction behavior, and wear resistance of the coatings were investigated. Dry reciprocating sliding tests were conducted under a load of 10 N, a frequency of 5 Hz, a stroke length of 5 mm, and a duration of 20 min using GCr15 bearing steel balls as the counterpart. The results showed that the 2 wt.% TiN coating exhibited the best tribological performance within the investigated composition range, with a microhardness of 579.6 HV0.5, a relatively low and stable friction coefficient of approximately 0.30-0.35, and a wear rate of 2.9 × 10-4 mm3/(N·m). When the TiN content increased to 4 wt.% and 6 wt.%, the wear resistance decreased, which was mainly associated with particle agglomeration, local stress concentration, and brittle spalling. These results indicate that appropriate TiN addition can improve the load-bearing capacity and wear resistance of laser-cladded AlCoCrFeNi coatings, providing a potential surface-strengthening strategy for 304 stainless steel components under dry sliding conditions.
As a typical Cr-Mo-V series hot work die steel, H13 steel is widely used in hot extrusion dies under harsh service conditions. Tempering is a vital post-quenching process for regulating microstructural evolution and comprehensive mechanical properties. Since relevant systematic comparative studies remain insufficient, industrial-grade H13 steel was adopted in this work. Specimens were quenched at 1000 °C, followed by single tempering at 520 °C and double tempering at 580 °C. Their microstructure, microhardness, and wear resistance at 25 °C and 580 °C were characterized, and the underlying mechanisms were analyzed. The results show that single tempering at 520 °C produces tempered martensite and finely dispersed carbides with secondary hardening behavior. Its microhardness reaches 590.83 HV, resulting in the best wear resistance at both room and high temperatures. Double tempering at 580 °C causes carbide coarsening, and the microhardness slightly declines to 580.60 HV. Although toughness is enhanced and residual stress is fully released, wear resistance deteriorates. This study optimizes the tempering parameters for H13 steel, provides technical support for die production, and offers theoretical guidance for the technical upgrading of the hot work die steel industry.
Wearable cardioverter-defibrillators (WCDs) are equipped with the TRENDS remote-monitoring system, enabling continuous assessment of arrhythmias, physiological parameters, and patient-reported outcomes. This study evaluated the clinical utility of TRENDS-integrated WCD management and compared it with a historical control. We prospectively analyzed 36 consecutive patients who received a WCD with TRENDS between 2019 and 2024 and compared them with 30 historical controls treated before the implementation of TRENDS. The WCD indications were heart failure as primary prevention (64%) and acute coronary syndrome with ventricular arrhythmias (28%). Among 18 patients who met the criteria for an implantable cardioverter-defibrillator (ICD), including 1 patient with WCD shock, 9 ultimately underwent ICD implantation. The mean daily WCD wear-time was 21.3 h and did not differ significantly from that of the historical control. The response rate to health-related questionnaires was 89%. TRENDS detected symptom exacerbation in 31% of patients, weight gain in 19% of patients, and missed medication in 19% of patients. Daily step-count was significantly lower in patients with ICD indications than in those without (5012 ± 2980 steps vs. 7977 ± 3584 steps, p = 0.01). TRENDS data also aided in initiating anticoagulation therapy and optimizing beta-blocker therapy. TRENDS provided clinically actionable physiologic and patient-reported information that supported individualized cardiovascular management.
To characterize the temporal profile of corneal recovery following apical clearance-fitted rigid gas-permeable (RGP) lens cessation in keratoconus and define a clinically feasible and sufficient period for reliable baseline morphology. This retrospective longitudinal study included 42 eyes of 23 patients with keratoconus newly fitted with standard aspheric (n = 18) or Rose K2 (n = 24) corneal lenses using an apical clearance approach. Corneal tomography was assessed at baseline, at 1st, 4th, and 12th week of daily lens wear (30 min after lens removal), and at 1st, 2nd, and 4th week after complete lens cessation. Longitudinal changes in sagittal corneal power and seven Pentacam indices were analyzed using linear mixed models. In the standard aspheric group, central corneal flattening was observed 30 min after lens removal; K2 at 4.0 mm decreased significantly from a baseline of 49.54 ± 0.81 D to 49.15 ± 0.82 D, and to 49.14 ± 0.81 D at 1st and 4th week (p = 0.005, p < 0.001 respectively, the later survived Bonferroni correction). In the Rose K2 group, no significant change of K1, K2 or Km was noted. Pentacam indices also showed significant deviations with the index of surface variance (ISV) decreasing significantly at 1st week in standard aspheric group (p = 0.0016, statistically significant after Bonferroni correction) after 30 min cessation. Following complete lens cessation, no statistically significant differences were observed in any sagittal power parameters or tomographic indices at 1st, 2nd, and 4th week compared with baseline values (all p > 0.05). Corneal morphological changes associated with a 12-week regimen of daily-wear apical clearance-fitted RGP lenses in keratoconic eyes were transient and returned to values not significantly different from baseline after one week of lens cessation.
On behalf of the editorial team, it is my great pleasure to introduce this Special Issue (SI) of Materials titled "Advances in Friction, Wear-Resistant and Solid-Lubricating Properties of Materials [...].
The autonomic nervous system, which regulates cardiac rhythm, undergoes pronounced maturation across adolescence. How cardiac rhythm develops over this period, however, and whether individual differences in its development forecast mental and physical illness, remain open questions. We used three waves of Fitbit data from the Adolescent Brain Cognitive Development (ABCD) Study to characterize the developmental trajectory of the cardiac rhythm and to test whether variation in that trajectory predicts onset of psychopathology and cardiometabolic disease. 8,301 adolescents contributed 242,811 valid Fitbit wear days across Waves 2 (Mage=12), 4 (Mage=14), and 6 (Mage=16). Cosinor mixed-effects models yielded three rhythm parameters per session: mesor (24-hour mean), amplitude (diurnal swing), and acrophase (peak timing). We first characterized age- and sex-specific trajectories, cross-wave stability, and factors shaping the rhythm. We then used parallel-process latent growth models to test whether within-person changes in rhythm tracked symptom trajectories, and hierarchical logistic models to test whether rhythm parameters predicted the first clinical onset of psychopathology and of obesity and hypertension. The cardiac rhythm changed substantially across adolescence: mesor decreased, amplitude flattened, and acrophase shifted later. Within-person change in the rhythm tracked change in blood pressure, BMI, and trajectories of depression and ADHD symptoms. Higher mesor predicted incident onset of all five outcomes controlling for demographics, baseline symptoms, and behavior (ORs 1.36-1.54); amplitude, acrophase, and rhythm instability conferred additional risk. The 24-hour cardiac rhythm is a passively measurable substrate of adolescent autonomic development that indexes transdiagnostic risk for psychiatric and cardiometabolic illness.
The microstructural characteristics and precipitate features of titanium matrix composites (TMCs) are critical to tribological performance. In this study, TiCp/TA15 composites were fabricated via laser powder bed fusion (LPBF). The as-built composite was then heat-treated at 750 °C for 2 h to obtain a uniform duplex (α + β) microstructure with enhanced TiC precipitation, which was labeled as HT-750. The influence of the microstructural evolution on the tribological performance was systematically investigated. Compared to the as-built composite, the HT-750 composite exhibited a microhardness increase from 360.2 ± 6.4 HV to 459.2 ± 3.1 HV, a reduction in the friction coefficient from 0.649 ± 0.167 to 0.581 ± 0.111, and a decrease in the wear rate from 8.24 ± 0.44 × 10-4 mm3/(N·m) to 4.81 ± 0.39 × 10-4 mm3/(N·m), indicating a significant enhancement in wear resistance. This improvement is primarily attributed to the synergistic strengthening effect of the duplex matrix and TiC particles, which enhanced the load-bearing capability and suppressed surface plastic deformation. During the friction process, the dominant wear mechanisms of as-built and HT-750 composites evolved over time but exhibited distinct differences. The as-built composites were prone to continuous plastic deformation and damage accumulation, resulting in severe delamination, oxidative, and abrasive wear. Conversely, the HT-750 composites demonstrated higher resistance to plastic deformation and crack propagation, effectively mitigating interfacial shear and inhibiting damage evolution, with the wear mechanism being dominated by oxidative wear accompanied by abrasive wear and minor delamination. This work provides deep insights into the wear mechanisms of additively manufactured TMCs.
Orthosis compliance monitoring provides insights into effective orthosis design and user wear time. Frequently, patient reports of orthosis use are subjective and often result in overestimation of compliance. Therefore, a tool to objectively observe whether patients wear their orthoses as instructed is vital. This study assessed the real-world practicality of using an objective compliance monitoring device with a hand orthosis. A device consisting of a pressure sensor and accelerometer was tested by ten healthy volunteers who wore a hand orthosis daily and completed a diary of their wear time and activities for a week. Sensor data obtained from the compliance monitoring device were analysed to discern each user's orthosis wear time. Differences between estimated wear time and actual wear time were insignificant. Pressure-based wear time estimations had a specificity of 99.3 ± 0.7% and a sensitivity of 80.3 ± 19.2%, whilst acceleration-derived estimations had a specificity of 94.5 ± 6.4% and a sensitivity of 73.2 ± 15.8%. This study demonstrated that orthosis compliance can be monitored outside the laboratory, and, furthermore, this device offers insights into the intensity and frequency of a user's activities and has the future potential to monitor orthosis fit and forces applied to affected joints using pressure.
Approximately 150 million people worldwide wear contact lenses, and most wear them successfully. However, contact lens wear is a major risk factor for developing infections and inflammation of the eye. This review outlines the need for antimicrobial contact lenses to help reduce the incidence of infection and inflammation. Antimicrobial peptides (AMPs) have been probably the best researched as antimicrobial coatings for contact lenses, with one of these (Mel4) progressing to a successful stage III clinical trial. Other antimicrobials including metals such as silver and selenium, and quorum sensing inhibitors have also progressed through to clinical trials. Currently only the Mel4 coated lenses have been shown to reduce the incidence of contact lens-associated inflammation. Unfortunately, no antimicrobial lens is yet available for sale, but the need is clear, and researchers, manufacturers and contact lens wearers are encouraged to continue their efforts in this space.