This study investigates the fatigue life of cord-reinforced rubber composites subjected to fully reversed threepoint bending. Although nominally a bending test, the high displacement amplitudes and low specimen stiffness lead to a tension-dominated loading state due to geometric nonlinearity. The research focuses on the influence of fiber orientation (0/90 degrees vs. +/- 45 degrees) and the number of reinforcement layers on fatigue durability. It was demonstrated that traditional parameters, such as strain amplitude or maximum strain, are insufficient to describe fatigue life under non-zero-mean-strain conditions. Instead, the Smith-Watson-Topper (SWT) and Walker models were successfully employed to unify the results. The findings reveal that +/- 45 degrees configurations exhibit superior fatigue life compared to 0/90 degrees layups under strain-controlled conditions, primarily due to fiber reorientation and lower internal stress levels. Analysis using the Walker model showed that single-layer composites are more sensitive to maximum strain (gamma = 0.3), whereas double-layer systems are dominated by strain amplitude (gamma = 0.7) due to interlaminar shear and internal friction. Furthermore, a critical relationship between matrix thickness and reinforcement ratio was identified: increasing rubber thickness improves durability in single-layer systems but deteriorates it in double-layer composites due to weakened crack-bridging mechanisms. SEM analysis confirmed these findings, highlighting the role of fiber pull-out and interlaminar degradation. Finally, the study highlights a lack of correlation between static tensile strength and fatigue performance, underscoring the need to account for viscoelastic effects in the design of cord-rubber structures.
Additive manufacturing (AM) of high-strength steels, such as 18Ni300 maraging steel, has attracted considerable attention in aerospace and tooling applications due to its excellent mechanical properties and design flexibility. However, the durability of AM components is significantly affected by both cyclic loading and environmental factors, particularly corrosion. This study investigates the combined effect of heat treatment and corrosive ageing on fatigue performance and hardness of additively manufactured 18Ni300 specimens. Corrosion tests were carried out in an ageing chamber according to ISO 9227 using the acetic acid salt spray (AASS) method for 7 days, at a temperature of 35 +/- 2 degrees C. Half of the specimens were exposed to these conditions, while the remaining samples served as a reference group. Hardness measurements (Vickers method) were performed to evaluate the influence of heat treatment and corrosion on surface properties. All specimens were subjected to cyclic loading to determine fatigue behaviour. Fractographic analysis was carried out to identify crack initiation and propagation mechanisms. The results demonstrate the influence of the corrosive environment on fatigue life and hardness, providing information on the degradation mechanisms and contributing to the optimization of post-processing strategies for AM maraging steels under demanding service conditions.
Following the successful vitrification and characterization of LiCoO2–P2O5 glasses containing 20–40 mol% LiCoO2 (5 mol% increments), the present study reports X-ray photoelectron spectroscopy (XPS) results and then focuses on their dielectric properties, ac/dc conductivity, and the examination of their suitability for solid-state batteries. XPS O 1 s results indicated that the amount of non-bridging oxygens increased with LiCoO2 content in the glasses, consistent with a network depolymerization effect. The presence of Co2+ and Co3+ was also verified by XPS; estimates based on the Co 2p3/2 satellites region indicated an increase in Co3+ concentration within ∼26–30% of total cobalt with increasing LiCoO2 content. The dielectric parameters, ac conductivity (measured from 4 Hz to 8 MHz and temperatures from 306 to 633 K) and dc conductivity in the same temperature range were found to increase, while the electrical impedance decreased with LiCoO2 content. Electrical modulus analysis and Cole-Cole plots revealed dipolar relaxation, with activation energy decreasing as LiCoO2 increased. This relaxation is ascribed to complexes of octahedrally coordinated Co2+ ions and surrounding oxygen ions. At higher LiCoO2 levels the conductivity (both ac and dc) is dominated by ionic contribution, whereas at lower concentrations, a polaronic contribution via electron hopping among Co2+ and Co3+ ions seemed to be significant. Overall, the results identify the higher-LiCoO2 glasses as promising candidates for further investigation as glassy solid-electrolyte materials, while the lower-LiCoO2 compositions may warrant investigation for electrode-related applications. Direct electrochemical measurements, including ionic transference, electrochemical stability, and cell-level cycling, are required to establish practical suitability for solid-state battery applications.
Chronic wounds impose a considerable clinical and economic burden, and their effective management requires objective, repeatable monitoring over time. Smartphone-based photogrammetry may enable acquisition of 3D metrics without the need for expensive dedicated scanners. This scoping review aimed to identify and organize digital methodologies applicable to wound measurement and monitoring, with particular emphasis on smartphone photogrammetry as a practical approach for routine care. A scoping review was conducted to identify digital wound measurement methodologies. The included approaches were organized according to the main pipeline stages: acquisition, reconstruction, and analysis. Reported metrics, including area, depth, volume, and tissue-assessment elements, were catalogued, and validation approaches, comparison methods, and implementation factors were summarized. In addition, a practical photogrammetry workflow with basic quality control (QC) gates is presented as pragmatic guidance informed by the reviewed literature for use during routine dressing changes. A review of the literature reveals that trend analysis, such as the percentage reduction over time appears to have high clinical relevance. Furthermore, the literature indicates that consistency and repeatability of measurement appear to be more important than single-measurement accuracy. Two-dimensional measurements can underestimate wound size on anatomically curved surfaces. In contrast, three-dimensional metrics, such as depth and volume, along with depth maps, may provide a more informative description of deep wounds. In deeper wounds, reductions in depth or volume (Z-axis changes) may precede visible reductions in the two-dimensional outline. The quality of the results appears to be strongly influenced by the acquisition conditions, such as angle, lighting, stability, and marker. The comparability of volumes is limited by the lack of clear definitions of the reference surface and inconsistent reporting of agreement and error metrics. Smartphone photogrammetry is an attractive implementation solution for clinics and telemedicine; however, its efficacy is contingent upon the standardization of acquisition, the integration of simple QC gates, and the establishment of transparent definitions of 3D metrics and compliance reporting. These measures may enhance comparability, facilitating reliable assessments between visits and centers.
