Material Design & Processing Communications最新文献

The fracture propagation on the rock causes failure and impacts the sustainability time of the structure. As part of the present work, sandstone with the variation of preexisting crack angle was simulated using the extended finite element method (XFEM). The crack propagation on sandstone has a preexisting fracture angle of 30°, 45°, and 60°, with an equivalent crack length. The impact of preexisting fracture angle on the possibility of crack propagation, failure mechanism, and displacement at a critical point of all models was studied. The numerical simulation revealed the crack angle of the model control vibration and its impact on the model’s seismic stability. The XFEM results are validated with reference to those available in the literature. Artificial neural networks (ANNs) are used for prediction by considering the training, testing, and validation process and analyzing prediction errors. The present simulation’s conclusion significantly supports the model’s displacement prediction with no crack propagation occurrence. In addition, by considering the preexisting fracture angle of a model, the load sustainability can be estimated.

In this study, the microstructure and defects of an Al-Mn-Mg-Zr alloy produced by the Powder Bed Fusion–Laser Beam (PBF-LB) technology are investigated. The influence of the process parameters on the microstructure and defects is demonstrated. Aluminum alloys are usually prone to cracking during solidification. However, finding the optimal parameters of the PBF-LB process yielded three-dimensional specimens of Al-Mn-Mg-Zr alloy with densities reaching 99.6% of the theoretical value, free from cracks. It is shown that manganese not only precipitates as a brittle Al₆Mn intermetallic compound after solidification but also forms a supersaturated solid solution of manganese in aluminum. The influence of the process parameters on the surface roughness of the manufactured samples and their microhardness was evaluated. It is also shown that the cooling rate of the melt pool has an effect on the microstructure of the samples obtained at the optimal process parameters.

This study used friction stir spot welding (FSSW) to weld 1.1- and 2.1-mm AA6061-T6 sheets at 560, 710, 900, and 1120 rpm at a fixed dwell duration of 5 s. It was determined how much heat was supplied into the FSSW, and the cycle temperature that occurred throughout the FSSW technique was carefully documented. Both the sheet metals and the formed FSSW weldments were subjected to micro and macrostructure analysis, as well as a lap shear test and a hardness test. A scanning electron microscope (SEM) was also used to study the cracked surfaces. A broad variety of rotation rates, ranging from 560 to 1120 rpm, were used to construct error-free spot joints, as shown by the macroanalysis. The microstructural results may show acceptable mechanical characteristics of FSSW joints, which pertain to the grain refinement of the joints’ stir zone (SZ). It was discovered that the optimal welding condition for establishing spot welds with varying thicknesses of thin sheets was 710 rpm. This was achieved with a SZ lap shear resistance of 5020 ± 20 N and hardness of 99 ± 2 HV₍₁₀₀₎. The temperature fluctuation and Von Mises stress distribution, in the AA6061-T6 FSSW sheets, were analysed by using ABAQUS/CAE 2021 software. The simulated peak temperature is rather similar to the recorded one. On the other hand, by raising the rotation speed, the peak temperature at the welded joints rose. The friction stir welding (FSW) procedures have an impact on the residual stresses; on the other hand, the welding parameters are influenced by the welding temperature and mixing.

In this study, microelectrical discharge machining (μEDM) is used for drilling microholes on a thin sheet of Ti Grade 2 alloy of thickness 50 μm using a tungsten carbide (WC) microtool of diameter 470 μm. The main focus of the study is to understand the electrical and nonelectrical μEDM parameters on the accuracy, precision, and machining efficiency of drilled holes. The controllable process factors such as capacitance, voltage, tool rotation, and feed rate are considered when conducting the experiments based on a Taguchi L16 orthogonal array. The main effect and interaction contour plots have been prepared to investigate the influence of the process parameters on the response measures like material removal rate, overcut, circularity, and taper angle of the drilled holes. Analysis of variance (ANOVA) has been carried out to study the percentage contribution and significance of each process parameter on the performance measures. The micrographic images reveal the quality of the profiles and edges of the drilled holes. Further, the Overall Evaluation Criterion (OEC) is applied for multiparameter optimization.

Foaming or porous geopolymers can be utilized in various engineering applications, including heat and acoustic insulations, as well as passive fire protection in building materials. They are ecofriendly materials, as no significant production power is required. In this study, geopolymers possessing foaming features involving lightweight and porous materials were successfully created through the reaction of sodium hydroxide solution 6 M with powder of waste glass MG without/with rice husk (RH) 20 wt.% of heat treated (212, 420, and 600 μm) utilized as the foaming agent. The effect of rice husk ash (RHA) and various sizes of RH additives on the thermal treatment (volume and weight changes, percentage), compressive strength, and microstructure (pore content) was assessed. The results show swelling (foaming behavior) for MG-N6, MGB-N6, MGR212-N6, and MGR600-N6 at 550°C, unlike the MGR420-N6 formula. Also, a high-volume change (percentage) for MGR420-N6 paste at 650°C was noticed. Additionally, foaming behavior (high volume expansion) appeared for all thoughtful pastes after treatment at 750°C. The weight loss for all specimens in the range of 10%–27% and a high percentage of weight changes for MGR400-N6 and MGR600-N6 were noticed. Low values of compressive strength (2.74–14.5 MPa) were recorded for all formulas studied. These synthesized materials, geopolymers containing glass waste and RH powder, resulting from this study, are highly recommended, mostly for thermal and acoustic insulation materials demanding lightweight, porosity, and low mechanical properties.

In this work, Ti-6Al-4V alloy was joined by tungsten inert gas (TIG) welding and the plates were undergone through optical microscopy test, elemental study, tensile test, hardness test, and fractographic observation. Plate-A, with low value of current input, possesses α + β bimodal structure at BM, acicular martensite at HAZ, and Widmanstätten structure with a low amount of martensite at the WZ. Plate-B, with comparatively higher value of current during welding, possesses similar structure at the BM. The HAZ area was comparatively lesser with significant martensite formation, and the WZ contains considerable formation of Widmanstätten structure. The elemental composition of BM and WZ was established by EDS. The stress-strain curves for both plates show that plate-B has almost 3%, 8%, and 7% greater UTS, YS, and elongation, respectively, than plate-A. The significant formation of Widmanstätten structure has made the WZ of plate-B more ductile and tough, although the fractography analysis of both the plates has shown macrodimples and flowing sign of metal as indicators of good ductility.

To produce a better connection and greater electron transfer efficiency between the TiO₂ particles, as well as to eliminate agglomeration and increase the dispersion of TiO₂ powders, a silicon dioxide/titanium dioxide (SiO₂/TiO₂) nanocomposite has been used as a photoanode in this study. An attempt was made to construct dye-sensitized solar cells (DSSCs) at a low cost with reasonable efficiency by replacing the highly costly platinum counter electrode with polypyrrole/sodium dodecyl sulfate (PPy + SDS) as Counter Electrode 1 (C1) and PPy/SDS/multiwalled carbon nanotube (PPy + SDS + MWCNT) as Counter Electrode 2 (C2), using Ru-based dyes Z907, pomegranate (Pom) dye, arugula (Aru) dye, and hibiscus dye as photosensitizers. The working electrode composite was deposited on fluorine-doped tin oxide (FTO) glass using a thermal chemical spraying approach, while the counter electrodes were produced using an electropolymerization method. The structural and optical characteristics are fully examined using several characterization techniques such as X-ray diffraction (XRD), Raman scattering, field-emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). The photovoltaic properties of the constructed DSSCs were assessed under light irradiation (100 mW/cm²). When compared to the reference cell based on the Pt counter electrode, which has an efficiency of 8.4%, the measured current–voltage (I–V) curve shows that the efficiency of DSSC in the case of Z907 dye with C1 and C2 was 3.037% and 3.743%, respectively. This suggests that the low-cost prepared DSSCs have good efficiency. Natural dyes show an efficiency range of 1.317%–0.66%, which indicates a moderate level of sensitivity.

Metal matrix nanocomposite coatings are promising for tribological applications given their superior hardness and wear resistance compared to metals. The point of this study was to describe the shape and long-term performance of nickel-based coatings that were put on stainless steel using electroless codeposition and made stronger with nanoparticles of zirconia (ZrO₂) and alumina (Al₂O₃). Scanning electron microscopy showed the uniform incorporation of nanoceramics within nickel matrices. Pin-on-disk tribotests evaluated wear performance across loads from 5 to 15 N and sliding speeds up to 480 cm/min. Increasing nanoparticle content from 2 to 4 g/L markedly reduced wear rate due to enhanced hardness and density. At all tested loads, Ni-ZrO₂ and Ni-Al₂O₃ nanocomposites exhibited considerably lower wear than monolithic nickel. The nanometal matrix particles hindered plastic deformation, with weight losses up to 68% lower than base nickel. Initially, wear resistance rose proportionally with sliding speed resulting from protective oxide layers until abrasive wear prevailed. The nanoparticle reinforcement dramatically extended durability, making it ideal for tribological systems involving mixed or abrasive conditions. More research needs to be done to find the best compositions and other matrix materials to use for these nanoscale strengthening effects.