In this study, the fracture characterisation under Mode I loading of Ti6Al4V alloy/carbon fibre reinforced polymer (CFRP) hybrid composites was investigated through mechanical testing and numerical simulations. Double cantilever beam (DCB) tests were performed to obtain the critical strain energy release rates (GIC) for the joints of Ti6Al4V/carbon fibre/low melt poly(aryl ether ketone) (CF/LM-PAEK) and Ti6Al4V-carbon fibre/poly (ether ketone-ketone) (CF/PEKK) composites. The Mode I interlaminar fracture energy (GIC) of the joints was evaluated using three different methods, including modified beam theory (MBT), compliance calibration (CC) and modified compliance calibration (MCC). The average GIC values of the LM-PAEK specimen obtained by the MBT, the CC and the MCC methods were 22.3%, 16.3% and 21.2% higher than that of the PEKK specimen. It shows that the LM-PAEK specimen had stronger adhesion than the PEKK specimen bonded with the Ti6Al4V sheet. Simulations were performed to investigate the interfacial behaviour of the Ti6Al4V/CFRP composites based on the cohesive zone model (CZM) using the LS-Dyna software. Results show good agreement between the experimental and the FEA results, with average errors of 2.28% for LM-PAEK and 4.36% for PEKK.
This study introduces woodnut fibre as a new natural fibre reinforcement for composite materials. This study involved the fabrication of woodnut fibre-reinforced polyester composites with four different fibre loading, both with and without ZnO doping, to evaluate how fibre loading affects the mechanical properties of the composites. The results indicate that adding 1 wt.% of total composite weight to the 20% fibre polyester composites significantly enhances the tensile strength by 17.54% (from 22.4 to 26.45 MPa). Peak flexural strength occurred at 25% loading, further increasing by similar to 222.65% with ZnO doping. The doping enhanced the impact strength by 127.07% at a 15 wt.% of fibre loading. With 1% ZnO doping, the maximum hardness increases to 455.5 HL at 15% fibre loading. TGA revealed that the composite without ZnO doping exhibited the highest degradation rate of 0.85%/degrees C. The findings indicate that woodnut fibre-particularly when modified with ZnO nanoparticles - offers significant promise as a sustainable and high-performance reinforcement for composite materials which are now used in the building industry for decorative laminates, wall panels, ceiling boards and insulation. Also used in consumer goods including helmets, luggage shells, electronic casings, storage boxes, packaging items like moulded trays, cushioning inserts and biodegradable containers.
This study investigates the influence of silicon nitride (Si3N4) and titanium diboride (TiB2) reinforcements on the density, microstructure, hardness and corrosion behaviour of Ti-10Mn composite. The results showed a reduction in relative density from 99.45% to 95.32% with the addition of manganese and ceramic particles, accompanied by a transformation of the microstructure from lamellar to equiaxed and elongated grains. The ceramic particles, located at grain boundaries, restricted grain growth, resulting in a significant increase in hardness from 245.8 to 496.8 HV0.5. Corrosion resistance was notably enhanced in the Ti-10 wt% Mn alloy (sample S5) containing Si3N4 and TiB2, as evidenced by a lower corrosion rate (0.321 mm/year) and current density (8.498 & micro;A/cm2) in 0.9 wt% NaCl solution. However, in Hank's solution, the corrosion rate (0.413 mm/year) and current density (11.717 & micro;A/cm2) increased, respectively. The combined effect of TiB2 and Si3N4 facilitated the formation of a dense, stable oxide layer, improved microstructural stability and refined the microstructure. Additionally, the reinforcements suppressed grain boundary corrosion by stabilising boundaries and improving passivity, thereby reducing anodic reaction rates. These findings highlight the potential of ceramic reinforcements to enhance the mechanical and electrochemical properties of Ti-10Mn composites.
The combination between additive manufacturing and microwave sintering (MW) is interesting as an alternative to conventional shaping and sintering processes. The aim of this study was to sinter centimetre-sized porcelain items shaped by robocasting in a set MW device, including a set sintering cell. Identical items were sintered in different positions in the sintering cell, to mimic the sintering of different objects in a predefined device. The position of the item in the sintering cell has a strong influence on its densification. A heterogeneous densification was obtained when the item was placed in a vertical position relative to the susceptors. It was not the case when the item was placed in a horizontal position. The temperature distribution in the susceptors and the items was simulated with a simplified 2D model. The calculated temperature in the item was dependent on the size of the item and on its position relative to the susceptor. This study highlights the need to carefully adapt the sintering cell to the object to sinter.
This study explores the influence of Activated Tungsten Inert Gas Welding (ATIG) welding on 6 mm thick UNS S32760 Super Duplex Stainless Steel (SDSS) and UNS S31703 Austenitic Stainless Steel (ASS), materials widely used in marine and chemical processing applications, using SiO2, TiO2, Cr2O3, and Fe2O3 fluxes at currents of 135, 145, and 160 A. The research focuses on analysing weld bead morphology, microstructure, and hardness properties, compared the results with conventional TIG welding. The findings show that every flux considerably increased penetration depth, with TiO2 flux providing 148.51% improved penetration in S32760 steel and SiO2 flux providing 128.44% greater penetration in S31703 steel. Additionally, SiO2 flux consistently produced a higher depth-to-width ratio in both materials. Microstructural analysis revealed that UNS S32760 welds exhibited austenite variants such as Grain Boundary Austenite (GBA), Widmanst & auml;tten Austenite (WA), and Intragranular Austenite (IGA), with Chromium Nitride (Cr2N) precipitates in the ferrite matrix, while UNS S31703 welds showed austenite grains such as columnar and equiaxed, with ferrite stringers at the austenite grain boundaries. Hardness tests showed increased weld zone hardness in S32760 steel for both ATIG and conventional TIG welding, whereas S31703 steel exhibited no significant hardness changes.
In peripheral milling, cutter deflection-induced form error is one of the unforeseen obstacles to manufacturers for achieving part accuracy without compromising productivity. This type of cutting force-induced surface errors do not have identical form along axial direction. The magnitude and shape of error profiles vary considerably with change in cutting conditions. In the current work, a methodology is identified to classify surface error profiles based on three angular parameters namely engagement angle, sweep angle and tooth spacing angle. Unlike the existing studies that typically focus on dimensional errors, the current work concentrates on a unified computational framework capable of predicting and classifying both dimensional and geometric errors simultaneously across a wide range of cutting conditions. Using a set of machining experiments, the results of the proposed classification scheme is validated. The paper also investigates the distribution of geometric errors (flatness) in a machined surface based on the estimated tool deflection values. The generic classification scheme provides a common platform about dimensional and geometric error of machined surface for a wide range of cutting conditions. The comprehensive discussions and classification of all possible profiles of surface errors will be helpful to product designer and process planners to select the desired surface accuracy of the component in design stage itself. In addition, it is also helpful to control and compensate them effectively.
A new laser lap welding process for titanium alloy/aluminum alloy was investigated to address the problem that a large number of brittle phases were generated in the joints. Based on the unique high entropy effect and diffusion hysteresis effect of high entropy alloys (HEAs), the self-designed CoNiCu1.25Nb0.5V1.25 HEA was applied as filler powder during welding to inhibit the formation of Ti-Al intermetallic compounds (IMCs), thereby improving the microstructure and mechanical properties of the joints. The results showed that when the welding line energy increased, the weld width increased, which was beneficial to the mechanical properties. At low welding line energy, a laser-welded joint without IMCs was obtained, mainly due to the two unique advantages of the HEA and a small amount of melting for base materials. With the increase of the welding line energy, a small number of TiAl3 and Al3V IMCs were detected near the fusion line on the aluminum alloy side, and (Ni, Co)Ti-2 solid solution was detected near the fusion line on the titanium alloy side. The maximum tensile strength reached 193MPa. The appropriate weld width and the reduction of the number of IMCs in the microstructure were the main reasons for improving the joint strength.
Linear friction weld (LFW) between EN8 medium carbon steel and AISI304 austenitic stainless steels was successfully made. EN8 was clamped on the stationary side, and AISI304 was clamped on oscillating side. Welds were fabricated at a frequency, friction pressure, forging pressure and weld time of 22 Hz, 225 MPa, 485 MPa and 20 s, respectively. Microstructural observation revealed the presence of characteristic microstructural zones, including the weld centre zone (WCZ), thermo-mechanically affected zone (TMAZ) and heat-affected zone (HAZ). The presence of EN8 grains forming a thin layer on AISI304 side of the WCZ indicated adequate intermixing. Microhardness was traced in the middle and at the ends of welded joint, and it was found to be greater in the middle than at the ends. Maximum hardness was observed on AISI304 side of joint interface in the middle region. The presence of stress-induced martensite was observed in the AISI304 TMAZ and HAZ. Tensile strength of 604.5 MPa with a 78% weld joint efficiency was obtained. The AISI304 and EN8 dissimilar welding has enormous potential in automobile, rapid transport systems and can bring about significant cost and weight savings, and design flexibility because of composites structures made from stainless steel medium carbon steel dissimilar joint.
Despite the numerous benefits of minimum quantity lubrication (MQL), it is yet to be used in small- and medium-scale machining industries due to the high cost of commercial MQL oils. The use of externally supplied MQL in drilling is challenging, as the cutting zone is inaccessible, and achieving good performance becomes difficult with increasing drilling depth due to the shadowing effect of the workpiece, which obstructs the aerosol. MQL and flood cooling in drilling AISI 304 steel with two different drill depths, 10 mm, and 15 mm are studied with a cutting speed of 35.46 m/min and feed rate of 0.05 mm/rev. To assess the penetration efficiency, cutting temperature is measured using a thermocouple inserted into the coolant hole of the through coolant drill held in a specially modified tool holder to perform drilling in a lathe. The maximum temperature obtained for MQL and flood cooling for 15 mm drill depth is 362.4 degrees C and 163.8 degrees C, respectively, with a percentage difference of 121.1%. Due to the workpiece shadowing effect, the lubricant/coolant reaching the cutting zone decreases drastically beyond 9 mm drill penetration for MQL and 12 mm penetration for flood cooling.
The growing emphasis on sustainable manufacturing has driven significant interest in recycled polylactic acid (rPLA) for fused deposition modelling (FDM), yet its mechanical performance particularly under cyclic loading remains underexplored. This study investigates the influence of key 3D printing parameters (print temperature: 190-220 degrees C, layer height: 0.1-0.2 mm, print speed: 40-60 mm/s) on the mechanical properties of rPLA using a Taguchi L9 experimental design. Results reveal that print temperature is the most critical parameter, with optimal performance achieved at 220 degrees C, 0.1 mm layer height, and 40 mm/s print speed, yielding a peak ultimate tensile strength of 47.82 +/- 0.30 MPa. Microhardness improved by 18% at higher temperatures due to enhanced layer adhesion, while fatigue performance improved under high-cycle loading conditions for samples printed under optimised conditions. Fractography analysis via scanning electron microscopy confirmed that lower temperatures (190 degrees C) introduced voids and weak interlayer bonding, whereas higher temperatures promoted denser microstructures. This study offers practical recommendations for enhancing rPLA in load-bearing applications, connecting sustainability with performance in additive manufacturing. The results support the implementation of high-temperature, low-speed printing to address the fundamental limitations of recycled polymers, promoting the objectives of a circular economy in 3D printing.
