Hot rolled 40Cr and W6Mo5Cr4V2 steels were diffusion-welded by using a 4-staged process including uniaxial 50 kN compression at 1200 oC in 10^-5 mbar vacuum with following cooling down to room temperature. Structural 40Cr and high-speed tool W6Mo5Cr4V2 steels are dissimilar, since they are different (i) in content of host Fe element and alloying Cr, W, V, Mo elements, (ii) in phase composition (40Cr steel is single-phased and W6Mo5Cr4V2 steel is multi-phased), (iii) in microstructure (homogeneous inclusions-less microstructure is characteristic for 40Cr steel, composite microstructure consisting of matrix Fe-based phase with metal (W, V, Mo) carbides is characteristic of W6Mo5Cr4V2 steel), and (iv) in grain structure (40Cr steel is coarse-grained with grain ~100 µm size and W6Mo5Cr4V2 steel is fine-grained with grain size of several µm). Phase composition, microstructure and grain structure of the steels are retained after welding. Diffusion redistribution of Fe, Cr, W, V, Mo atoms results in forming the diffusion zones with different widths (several µm for W, V and Mo, ~25 for Cr and ~15 µm for Fe). Resulting concentration Cr profiles are typical for diffusion from limited sources and could be satisfactorily described by diffusion coefficient equal to ~1.1∙10^-14 m²∙s^-1 (the coefficient is weighted over the entire temperature range from 1200 oC to room temperature). Within the diffusion Cr and Fe zones, the Vickers microhardness decreases from ~2000 HV (for W6Mo5Cr4V2 steel) to ~530 HV (for 40Cr steel). During room-temperature tensile tests, the diffusion-welded steels were always fractured not in the diffusion joint but in 40Cr steel.

Additive manufacturing by direct metal fabrication represents one of the fastest-growing areas in material science and manufacturing. Modern manufacturing demands that parts be engineered to have high strength, be lightweight with complex geometrical details, and be suitable for operation upon completion. A very good example of such engineering-manufacturing involves the design and manufacturing of turbine blades for energy efficiency. On the other hand, topology-optimized lattice structures have huge potential and flexibility available to designers operating in the area of designing lightweight structures and high-strength ones at the same time, in contrast to solid form structures. The key issues involved in the research include designing graded density structures made from different lattice architectures for dense materials by characterization of the thermo-mechanical properties for a number of lattice settings in Gyroid, Diamond, Schwarz, Lidinoid, Split P, and Neovius lattices for varied parameters. This paper questions how appropriately the design structure functions in high-speed-rotating elements, such as turbine blades. The current research work will be aimed at the design, finite element analysis for simulation, and manufacturing through additive manufacturing of the turbine blades, considering several designs and lattice structures that satisfy the requirements of lightweight construction and high strength. A detailed preliminary design study has already been performed with the aim of justifying the idea presented in this paper and to create an initially validated basis. It therefore presents findings from the design of different lattice structures, supported by simulations that explain the potential, extent, and limitations of the proposed paper with regard to its general scope.

Lightweight structures tend to be susceptible to vibration, which can lead to fatigue and failure. Piezoelectric shunt damping is an efficient technology that converts mechanical energy into electrical energy and dissipates it through shunt circuits without requiring external power. This study models several piezoelectric patches coupled to different shunt circuits on a thin plate, utilizing Rayleigh-Ritz modal analysis to examine patch parameters including size, position, and distribution. Optimization demonstrates that effective patch-circuit topologies correspond with structural mode shapes, resulting in maximum vibration reduction. The findings introduce a fresh technique to enhance vibration control which improves structural reliability and performance.

This study reports on microstructure evolution and mechanical properties of weld joints of two ASTM A335 P92 steels with varying chromium and tungsten content influenced by heat treatment. Physical simulation samples for fine-grain and intercritical heat-affected zones were done using the Gleeble® 3500 equipment. A peak temperature of 900°C (intercritical zone) and 950°C (fine-grained zone) simulated different heat-affected zones. After physical simulation, the test samples underwent two heat treatment schedules: post-weld heat treatment (PWHT) and normalisation, followed by tempering. The results show that the two steels had similar martensite microstructure. The microstructure further exhibited the presence of M23C6 carbides along the grain and lath boundaries. The P92-B steel had the highest hardness values after heat treatment except at FGHAZ + PWHT condition, which had a lower hardness value (271.9 ± 5.0 HV0.5). In this condition (FGHAZ + PWHT), P92-B steel had a higher Charpy toughness value (180J), slightly higher than the base metal (178J) due to fully formed martensite microstructure. ICHAZ + heat treatment, P92-B steel had the lowest toughness values (74J for r-PWHT and 83J for PWHT), but these values were higher than the minimum toughness value of 47J of the weld joint required for hydro-testing of the vessels. The study revealed no marked significant differences between the two steels. The heat treatment method (r-PWHT) is applicable in the industry for Type IV crack mitigation of the weld joint.

Reinforced concrete deep beams (RCDBs) investigations are often complex because of the highly disturbed zones which may aggravate the shear performance under variable loadings. The shear capacity enhancement of RCDB using different aggregate sizes of 19 mm, 25 mm, and 50 mm has been investigated under three-point monotonic loading. Nine RCDBs with 750 × 170 × 225 mm dimensions were considered, and the beam was loaded at a 1.4 shear span to depth ratio. Three of the beams were designed without web reinforcement, and six were designed for web reinforcement with varied aggregate sizes. There was no significant difference in the shear strength of RCDBs considered however, a 50 mm aggregate beam was found capable of reducing the multiple crack propagations when compared to other aggregate-size beams. Additionally, the shear reinforcement increased the ductility and strength by over 30% and 20%, respectively. The applicability of 3-dimensional FEM extended to the investigation acceded with the shear response of the experiment exercising shear stiffening behavior. The estimated model from the modified ACI 318:05 can predict the shear capacity of the RCDB with higher accuracy. Since aggregate resists the load by aggregate interlock action, it is crucial to choose the right aggregate when building concrete structural components. The results of this study will help engineers choose the best aggregate for a certain structural element.

This research pioneers the development of an innovative approach for refining dental implant fixture surfaces using the SLA+Anodizing method. Leveraging a rich dataset encompassing 68 distinct implant surface treatment states, the study employs an Artificial Neural Network (ANN) to predict crucial parameters such as surface roughness and cellular viability. Through meticulous training and validation, the ANN demonstrates a remarkable 3% error rate in comparison to experimental results, underscoring its precision. The methodology extends beyond prediction, facilitating the optimization of implant surfaces for enhanced osseointegration. Experimental validation, including Atomic Force Microscopy and Molecular Cytotoxicity Tests, corroborates the accuracy of the ANN predictions. The study pioneers a transformative era in dental implantology, introducing a tailored and adaptable approach that bridges gaps in understanding the intricate interplay between surface modifications and biological responses. This work sets the stage for a paradigm shift in dental science, emphasizing precision, personalization, and elevated standards of care.

In the current decade, a number of industries have moved their attention towards emerging sustainable technologies in order to better support socio-economic and environmental considerations. The present research investigates a unique hybrid composite developed by the amalgamation of natural kenaf-coir fibers, with resin of epoxy, incorporated with titanium carbide (TiC) nanoparticles. This study also presents the development process involved in manufacturing the composites, along with mechanical testing and optimization of these composite samples. The nanofillers of TiC are utilized in wt. percentages of 0%, 3%, 4%, and 5%, while coir and kenaf fibers are incorporated at 0%, 3%, 4%, and 5% by weight, and the thickness of the samples is varied at 2, 3, 4, and 5mm. The mechanical attributes of composites are evaluated using a vacuum bag molding process, with subsequent testing and optimization performed through Taguchi and ANOVA analysis to discover the optimal sample combination. The findings indicate that the most effective composite formulation includes 4% TiC, 5% kenaf, 5% coir, and a thickness of 3 mm, which provides the highest tensile modulus and strength among all tested samples. The integration of kenaf fibers with coir fibers and TiCs as fillers significantly improves the tensile and flexural attributes of the hybrid composite in contrast to composites made with coir or kenaf fibers alone.