This study examines the Charpy impact response and surface hardness of glass fiber–reinforced polymer (GFRP) and carbon fiber–reinforced polymer (CFRP) laminates produced viaVacuum Assisted Resin Transfer Molding (VARTM). Notched specimens with three distinct plyorientations—0°, 0/90°, and 30°—were evaluated experimentally, and failure surfaces werecharacterized by stereo microscopy (SM). Among the orientations examined, the 30° configurationyielded the greatest energy absorption in both material systems. GFRP laminates consistentlyoutperformed their CFRP counterparts in impact capacity, recording roughly 46% higher absorbedenergy. The orientation-induced improvement was considerably more marked for CFRP(approximately 213%) than for GFRP (approximately 76%). One-way analysis of variance(ANOVA) confirmed the statistical significance of ply orientation on impact response, and residualexamination verified that no data points deviated beyond ±2 standard deviations. Moreover,fractographic evaluation indicated that GFRP specimens failed mainly by fiber pull-out and elasticdeformation of the fiber–matrix interface at oblique orientations, whereas CFRP laminatesdisplayed a brittle fracture character involving fiber breakage, interfacial debonding, andinterlaminar splitting. The collective results underscore the decisive roles of fiber type and plyorientation in controlling impact performance and damage evolution in VARTM-processed epoxycomposites.
This study investigates the influences of polylactic acid (PLA) molecular weight on mechanical behaviors and morphological property of polyvinyl alcohol (PVA)/PLA biomaterial blown films. Three commercial PLAs (L105, L130, and L175) with distinct molecular weights are individually blended with PVA at a fixed ratio of 50 wt%. Glycerol (20 phr) is employed as a plasticizer to enhance film processability. Films are fabricated via twin-screw extrusion followed by film blowing. Morphological observations confirm that interfacial adhesion and phase distribution are dependent on both PLA molecular weight and content. Mechanical analysis demonstrates that biomaterial PVA blown film with PLA L175 exhibit superior tensile strength and ductility due to improved interfacial entanglement. These findings highlight the critical role of interfacial interactions in tuning the structure–property relationship of PVA/PLA biomaterial systems, supporting their development as flexible, biodegradable films for advanced packaging applications.
This paper presents a comparative finite element investigation of three sleeper models: a prestressed monoblock concrete sleeper named Model 1, a GFRP sleeper with identical geometry but no reinforcement named Model 2, and Model 3 for a GFRP sleeper with a composite sleeper standard geometry according to ISO13230-1. Harmonic response analyses under 180 kN and 320 kN axial loads revealed severe dynamic deficiencies in Model 1, with extreme resonance-induced stresses reaching 5629.1 MPa at 714 Hz under 320 kN, which exceeded the concrete strength capacity. Although Model 2 benefited from GFRP’s enhanced damping, its standard geometry led to critical stresses up to 839.0 MPa at 324 Hz, which is beyond the GFRP yield strength (75 MPa). In contrast, Model 3 demonstrated effective stress control under 180 kN, meeting IRS safety requirements with peak stresses of 74.2 MPa at 250 Hz. All models exhibited a peak response at their third vertical bending mode, however, GFRP sleepers showed smaller amplitudes which confirms their stability under dynamic loads. Dynamic advantages of GFRP sleepers are fully realised through concurrent optimisation of material properties and geometry. These outcomes show the potential of GFRP sleepers as a robust, safer, and more durable alternative for next-generation high-speed railway infrastructure.
The study was conducted on POIn-52 solder in the form of a foil with a thickness of 200 μm and three-and five-layer POIn-52–Pb composite materials. Data were obtained on the influence of various technological parameters on the properties and structure of solders in the free state and in the form of layered composite materials. These data are necessary for choosing the optimal soldering technology and the possibility of creating compositions using solders. The influence of the interfacial surfaces of composites and their degradation under the influence of heating is shown. Along with mechanical methods of research, metallography and X-ray structural analysis methods were used in the work. The results of mechanical tests in the mode of active tension of POIn-52 and POS-61 solder foils (for comparison) depending on the temperature are necessary to ensure the reliability of the operation of soldered joints under conditions of cyclic temperature changes. It was established that the mechanical properties of composite materials in the form of lead tape, which is clad with soft solder POIn-52, differ sharply from the properties of the constituent materials, which is due to the influence of diffusion processes on the interfacial surfaces. The rational soldering temperature of the composite material was determined, and the inexpediency of using five-layer composites in the outlined operating conditions was also shown.
Bone drilling is a critical surgical procedure in orthopaedic, dental, and maxillofacial surgery, during which excessive bone temperature elevation at the tool-bone interface can cause thermal osteonecrosis (bone temperature > 47 °C). The subsequent effects compromise osseointegration and implant stability. Drill coating material could regulate both frictional heat dissipation and mechanical cutting resistance. However, the comparative thermomechanical performance of titanium nitride (TiN), titanium carbonitride (TiCN), titanium carbide (TiC), and diamond coatings across multiple simultaneous drilling responses has not been systematically quantified under designed experimental conditions. A Box-Behnken Design (BBD) comprising 60 finite element simulation runs (15 per coating block, 3 centre points per block) was employed to develop second-order response surface methodology (RSM) models for maximum bone temperature and thrust force. Analysis of variance (ANOVA) revealed that the quadratic model was highly significant (F = 137.79, p < 0.0001), with coating material (D) as the dominant factor (F = 497.40), followed by spindle speed (A, F = 702.67), feed rate (B, F = 412.86), and drill diameter (C, F = 177.92). All three coating-by-continuous-parameter interactions (AD, BD, CD) were insignificant (p > 0.19), which indicates that the thermal advantage of diamond over TiN reveals as a uniform absolute offset independent of continuous parameter levels. Multi-objective desirability optimization identified a diamond coating at 944 rpm, 0.020 mm/rev, and 2.8 mm diameter as the optimal condition (d = 0.981), producing the lowest bone temperature (59.8 °C). These findings provide statistically validated guidance for coating selection and the design of surgical drilling protocols to minimize thermal bone damage.
