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The utilization of Fused Filament Fabrication (FFF) technology for developing sandwich structures proves to be an effective approach, enabling the rapid construction of intricate profiles and gaining widespread recognition for diverse structural applications. In this study, hexagon lattice-cored sandwich structures are created by situating the lattice core at the center of the PLA polymeric specimens. The performance is assessed by varying 3D-Printing Factors (3D-PFs), including Nozzle Temperature (NT), Layer Height (LH), Printing Speed (PS), and Line Width (LW). The levels of 3D-PFs are manipulated as follows: NT (180, 190, 200, 210°C), LH (0.15, 0.2, 0.25, 0.3 mm), PS (15, 20, 25, 30 mm/sec), and LW (0.1, 0.2, 0.3, 0.4 mm). By employing a FFF 3D printer, the sandwich specimens are 3D-printed and their compression properties are assessed using a Universal Testing Machine (UTM). In this research, various Machine Learning (ML) models namely Bayesian Ridge regression (BRid), Elastic Net linear regression (EN), Quantile Regression (QR), and Support Vector Machine (SVM) are utilized to predict the compressive strength/density property of the developed sandwich structure. This aids in determining the optimal levels of 3D-PFs to achieve enhanced compressive strength/density. The results reveal that the QR model, particularly when employed in the boosting ensemble technique, exhibits superior accuracy with a Root Mean Square Error (RMSE) of 0.26 × 104, Mean Absolute Error (MAE) of 0.21 × 104, and Median Absolute Error (MedAE) of 0.16 × 104. Utilizing the QR model within the boosting ensemble technique, the influence of 3D-PFs on resulting compressive strength/density is analyzed, facilitating the identification of optimized 3D-PF levels for improved compressive strength/density. Sandwich structures fabricated at these optimized levels demonstrate enhanced compressive properties, making them suitable for a variety of structural applications. [ABSTRACT FROM AUTHOR]

Recently, composite filament development for three-dimensional printing has emerged and is used for numerous applications. The present research work develops neat polylactic acid and Almond Shell Particles reinforced polylactic acid bio-composites for three-dimensional printing and investigates the effects of printing orientation, including 0°, 45° and 90° orientation, on the tribological and mechanical behaviours of three-dimensional printed materials. The novel almond shell particles reinforced polylactic acid filaments are extruded by the filament extrusion method with the presence of 10% almond shell particles in the polylactic acid matrix, and the samples are three-dimensional printed by the fused filament fabrication technique. Mechanical characteristics such as tensile, flexural, compressive strength, and shore hardness are evaluated with respect to various three-dimensional printing orientations. The surface quality of the three-dimensional printed polylactic acid composite samples is analysed with respect to length and diameter deviation. Length accuracy of the 90° oriented polylactic acid and almond shell particles reinforced polylactic acid bio-composite samples exploits a better accuracy of 99.12% and 98.81%, respectively. It is shown that adding almond shell particles to the polylactic acid matrix decreases the flexural and tensile strength. Among the printing orientations, 0° flat samples result in the maximum tensile strength of 36 and 28 MPa for the neat polylactic acid and almond shell particles reinforced polylactic acid composites, respectively. The lowest contact angle of 54° is observed on the almond shell particles reinforced polylactic acid bio-composites three-dimensional printed with a 90° orientation. The highest contact angle value of 94° is observed on the neat polylactic acid three-dimensional printed with a 0° printing orientation. A tribological study is carried out under dry conditions on the pin-on-disc tribometer by varying the sliding speed (1, 2, and 3 m/s) and load (10, 20, and 30 N). The result shows that the lowest coefficient of friction of 0.22 is achieved for the almond shell particles reinforced polylactic acid bio-composite samples with a 0° printing orientation under a sliding load of 10 N. These kinds of newly developed compostable materials can be used for developing disposable orthotic foot appliances. [ABSTRACT FROM AUTHOR]

Engineering, architecture, and transportation all use honeycomb structures in various ways. Latticing, made possible by additive manufacturing (AM), may significantly speed up the creation of adaptable structures. The current study focuses on assessing the impact of various three-dimensional (3D)-printing features on the flexural behavior and dimensional studies of the honeycomb latticed micro-carbon fiber reinforced nylon (ONYX) material. The experiment is performed by varying the levels of 3D-printing features like layer thickness (LT), infill geometry (IG), build direction (BD), shell count (SC), and infill percentage (IP) to measure the bending strength, length deviation, and lattice surface morphology variation. The experimental results show that, the peak flexural strength of 79.84 MPa is attained with specimen fabricated at 0.1 mm LT, 50% IP, 0° BD, rectilinear IG, and SC of 3. And moreover, these respective 3D-printing feature levels resulted in an improved surface morphology on the latticed specimens. The length deviation results clearly depict that specimen fabricated at lower LT of 0.1 mm, higher SC of 3, rectilinear IG, 0° BD, and higher IP of 50% consequences in accurate profile with a lower length deviation of 0.117 mm. The fractography results clearly implies that the 0° oriented latticed ONYX composite results in a progressive fracture and results in higher bending stress. On the other hand, the 45° and 90° oriented latticed ONYX materials undergo tilted fracture and perpendicular mode of fracture, respectively. From that it is concluded that, the triangular-shaped honeycomb latticed ONYX materials are suitable for the development of brackets for the portable cameras, medical, and dental appliances like prosthetics for lightweight splints in postsurgery. [ABSTRACT FROM AUTHOR]

In this study, we investigated a radiative chemically reactive Casson fluid above a cone, plate, and wedge with gyrotactic microorganisms subjected to the Cattaneo–Christov heat flux model. Newton’s method and the Runge–Kutta methods were employed to solve the physical problem, and a graphical representation of the numerous impacts of non-dimensional parameters on temperature, velocity, and concentration was created. In addition, we also compared recently published solutions with our current solution, which showed good agreement. From this investigation, we concluded that the motile organisms’ momentum, temperature, and concentration density were non-uniform in nature. Here, for engineering importance, we also present the mass transfer and thermal transfer rate over the cone, wedge, and plate cases in a tabular form. We concluded that the mass and heat transfer rate was larger over the cone when compared to the same case over a plate or wedge. The results also highlighted that the local Nusselt and Sherwood numbers and the mass density of the microorganisms depreciated as the Casson fluid parameter decreased. In summary, we concluded that the gyrotactic microorganisms played a role in enhancing the local Sherwood number.

Abstract:Tooth enamel is the most mineralized tissue in the human body, and in this article the use of Raman spectroscopy for the analysis of tooth structure, a comparison with synthetic apatites, and use in dentistry are described. Spectral peaks that are related to dental hard and soft tissues are discussed, which provide crucial data in understanding the chemical structural properties of dentin and enamel. The Raman spectrum of dentin confirms the presence of crystalline phosphate-based minerals in dentin. Both dentin and enamel consist of two primary components: an inorganic or mineral phase that closely resembles hydroxyapatite and the Raman spectrum of dentin that confirms the presence of crystalline phosphate-based minerals in dentin. Hence, the mineral phase in dentin and enamel may be characterized essentially as nonstoichiometric substituted apatite. The presence of carbonate (A and B type) incorporated in the hydroxyapatite lattice is also confirmed by the presence of spectral bands. The organic phase, which is mainly composed of type I collagen, is confirmed by the spectral bands of amide I and amide II bands, tryptophan, and phenylalanine. Furthermore, these spectral bands associated with organic and inorganic parts of the enamel and dentin are useful in predicting early formation of carries formation. [ABSTRACT FROM PUBLISHER]