International Journal of Mechanical and Materials Engineering最新文献

This study investigates the utilization of Ti/Ni reactive multilayer foils as an energy source for facilitating the joining of Ni–Ti shape memory alloys through diffusion bonding. Multilayered samples were prepared using a 10-cycle accumulative roll bonding (ARB) process to be used for the bonding process. Diffusion bonding employing reactive multilayers was conducted over a temperature range of 600 °C to 900 °C, at 5 MPa pressure, with a 1-h hold time. Additionally, a comparison was made with a diffusion-bonded Nitinol sample at 900 °C without a reactive multilayer. Materials characterization and testing involved scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), shear strength testing, and differential scanning calorimetry (DSC), which were conducted on the bonded samples. The findings underscored the advantages of using reactive multilayers for diffusion bonding. These benefits included the formation of TiNi and the induction of a shape memory effect in the joint region, alongside a 1.5 times shear strength compared to identical diffusion bonding conditions without reactive multilayers. Moreover, employing reactive multilayers in the diffusion bonding of Nitinol holds promise for significantly reducing the energy needed to achieve robust and seamless bonded boundaries in the joining area.

Cohesive flexible rectorite clay films with good mechanical performance were prepared by a simple casting method through the self-assembly of exfoliated natural clay from aqueous dispersions. The multi-layered microstructure of the films consisted of continuous layers of aligned clay platelets parallel to the casting surface. Layers overlap randomly in the lateral direction (plane) and join vertically in an irregular manner by edge-to-face cross-linkages (bridging) to form coherent multi-layered nanostructured films with platelet-void microstructure. The films with the highest mechanical properties had thicknesses below 30 µm. Overall films from rectorite clay with monovalent interlayer content exhibited a higher experimental tensile strength ranging up to 44 MPa and Young’s modulus up to 56 GPa. The corresponding experimental values for films with divalent interlayer cations were 23 MPa for strength and 25 GPa for modulus. The highest experimental values for strength and modulus for neat Na–Ca–rectorite films were 25 MPa and 50 GPa respectively. These two mechanical property values of the best rectorite-based clay films compare favorably with values featured by polymer films typically used for packaging applications.

Due to their versatile properties and wide-ranging applications across various industries, including manufacturing, polymers are indispensable for today’s society. However, polymer-based products significantly impact the environment since many are single-used plastics and require a long time to degrade naturally. A method to attenuate end-of-life polymers’ ill effects is recycling them to bring them again into the production cycle, from grave to cradle. This investigation involves recycling PETG sheets used in face shield production during the COVID-19 outbreak to fabricate 3D printing filaments for FFF. We assessed poly(ethylene terephthalate) glycol (PETG) processability to up to five recycling cycles and obtained filaments with properties adequate for 3D printing. Rheological, thermal, morphological, and mechanical characterization were analyzed to verify the effect of the number of processing cycles on the properties of the polymer. The recycling cycles originated a decrease in viscosity and elasticity, and the gain in molecular mobility resulted, relatively, in solids with a higher degree of crystallinity and prints with more elliptical depositions. The mechanical properties of printed parts fabricated of recycled material were comparable to those from commercial filament, especially after three extrusion cycles. Both extrusion and additive manufacturing processes successfully recycle material into filaments and printed parts, indicating that the proposed methodology is a promising alternative to bring value back to polymers from solid waste.

In this paper, a shape memory alloy (SMA), NiTiNOL, zigzag sheet is used and experimental method is developed using programmable power supply, laser displacement sensor, and K-type thermocouple to investigate actuation and thermo-mechanical behavior of trained SMA zigzag sheet under three different weights, 2.5 N, 3.5 N, and 4.5 N, along with three distinct voltage levels 2.0 V, 3.0 V, and 4.0 V and hysteresis curves are comprehensively examined to get optimum value of load and voltage to achieve better life cycle and actuation as per the requirement of the design. The displacement and temperature data of the zigzag sheet is recorded for every 200 ms for the entire operating life, utilizing heating and cooling processes, of the zigzag sheet and the value of constant displacement for each cycle is optimized which can be used for the development of microelectromechanical systems (MEMS).

Perovskite materials have emerged as promising candidates for next-generation photovoltaic devices due to their unique optoelectronic properties. In this study, we investigate the incorporation of bromine into cesium lead mixed iodide and bromide perovskites (CsPbI_3(1-x)Br_3x) to enhance their performance. By depositing films with varying bromine concentrations (x = 0, 0.25, 0.5, 0.75), we employ a combination of structural and optical characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy, and photoluminescence. Our analysis reveals that introducing bromine leads to structural modifications, influencing the perovskite films’ optical properties and energy gap. Specifically, we observe semiconductor behavior with a tunable energy gap controlled by the intercalation of bromine atoms into the CsPbI₃ lattice. Furthermore, heat treatment induces phase transitions in the perovskite films, affecting their optical responses and crystalline quality. SCAPS-1D simulations confirm the improved stability and efficiency of bromine-doped CsPbI₃ films compared to undoped counterparts. Our findings demonstrate that bromine incorporation facilitates the formation of highly crystalline perovskite films with reduced trap defects and enhanced carrier transport properties. These results underscore the potential of bromine-doped CsPbI₃ perovskites as promising materials for high-performance photovoltaic applications, paving the way for further optimization and device integration.

This work explores environmentally conscious machining practices for AISI4140 steel through Taguchi analysis. The study employs a design of experiments (DOE) approach, focusing on cutting speed, depth of cut, and coolant type as parameters. Taguchi’s L9 orthogonal array facilitates systematic experimentation, and the results are analyzed using MINITAB 17 software. Signal-to-noise ratios (SNR) are utilized to establish optimum operating conditions, evaluate individual parameter influences, and create linear regression models. The experiments reveal neem oil with graphene coolant as an eco-friendly solution, addressing health and environmental concerns. Main effects plots visually represent the impact of parameters on machining quality. Additionally, regression and artificial neural network (ANN) models are compared for surface roughness prediction, with ANN showing superior performance. The findings advocate for optimized cutting conditions, emphasizing material conservation, enhanced productivity, and eco-friendly practices in AISI4140 steel machining. This research contributes valuable insights for industries seeking sustainable machining solutions.

This paper presents a new method for detecting malathion pesticides using a modified screen-printed electrode (SPE) with a fluorescence quenching technique. The manganese-based MOF was synthesized using the solvothermal method. The synthesized MOFs were characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The material’s electrocatalytic properties were assessed via electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Within the concentration range of 0.89 µM to 5.95 µM, the material’s response to malathion was analyzed with square wave voltammetry (SWV), giving rise to a detection limit of 39.097 nM. Fluorescence quenching studies have been carried out between 0.039 and 0.56 µM, with a lower detection limit of 62.03 nM. A sensor with good anti-interference properties was tested for selectivity and practicability in detecting malathion in real samples, proving its potential use in this area.

Decellularized amnion (dAM)-derived hydrogels have been extensively exploited for versatile medical and therapeutical applications, particularly for soft tissue engineering of skin, vascular graft, and endometrium. In contrast to polyacrylamide-based hydrogels, which have been extensively employed as a 3D cell culture platform, the cell response of dAM hydrogel is yet to be understood. In this study, we have prepared hydrogels containing different concentrations of dAM and systematically investigated their microstructural features, gelation kinetics, and rheological properties. The results show that dAM hydrogels possess a network of fibers with an average diameter of 56 ± 5 nm at 1% dAM, which increases to 110 ± 14 nm at 3% dAM. The enhanced intermolecular crosslinking between the microfibrillar units increases the gelation rate in the growth phase of the self-assembly process. Moreover, increasing the concentration of dAM in the hydrogel formulation (from 1 to 3%w/v) enhances the dynamic mechanical moduli of the derived hydrogels by about two orders of magnitude (from 41.8 ± 2.5 to 896.2 ± 72.3 Pa). It is shown that the variation in the hydrogel stiffness significantly affects the morphology of dermal fibroblast cells cultured in the hydrogels. It is shown that the hydrogels containing up to 2%w/v dAM provide a suitable microenvironment for embedded fibroblast cells with spindle-like morphology. Nevertheless, at the higher concentration, an adverse effect on the proliferation and morphology of fibroblast cells is noticed due to stiffness-induced phenotype transformation of cells. Concentration-modulated properties of dAM hydrogels offer an in vitro platform to study cell-related responses, disease modeling, and drug studies.

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This study explores how expanded thermoplastic polyurethane (ETPU) responds to temperature and compression at various temperatures. Dynamic mechanical thermal analysis (DMTA) was used to understand the temperature influence at small deformations. To investigate the deformation behavior at different compression stages we employed in-situ CT measurements and 3D strain mapping. Through quasi-static compression tests at temperatures from − 50 to 120 °C, we determined the influence of temperature on compression modulus, elastic stress, stress at 50% deformation, densification, and energy absorption. Remarkably, ETPU demonstrates robust recovery after compression, particularly within the − 50 to 60 °C temperature range. Subsequent compression tests show consistent or even slightly increased compression properties, such as a 10% increase in energy absorption for samples previously tested at − 40 °C, indicating that ETPU can withstand prior exposure to different temperatures.

To ascertain upon the ideal configuration of physico-mechanical qualities, efficient processing techniques, and network stability of the prepared bio-composite films in real-world applications, the polymeric materials shall be subjected to a careful manipulation. Such bio-composite films have outstanding combinations of biocompatibility and toxicity-associated safety qualities. Such research interventions will be beneficial for the packaging, pharmaceutical, and biomedical industries that wish to target and adopt them for commercial applications. In this article, three alternate organic acids, i.e., citric acid (CA), tartaric acid (TA), and malic acid (MA), are blended separately into polyvinyl alcohol (PVA)-starch (St)-glycerol (Gl) composite films and for the targeted purpose of enhanced crosslinking, plasticizing, and antibacterial capability of the polymer network. The organic acid-based bio-composite polymeric films were assessed in terms of swelling index (SI), in vitro degradation, tensile strength (TS), percentage elongation (%E), antibacterial activity, and cytotoxicity attributes. Among these, the MA-based PVA composite films outperformed the CA-based PVA composite film in terms of absorbency (SI 739.29%), mechanical strength (TS 4.88 MPa), and elasticity (%E 103.68%). Furthermore, following a 24-h incubation period, the MA-based films exhibited the highest proliferative effect of 215.59% for the HEK cells. In conclusion, the MA has been inferred to be the most relevant organic acid for the desired optimality of film composition, physical and biological properties, and cost.