Material Design & Processing Communications最新文献

Mild steel is a common material used extensively in the manufacturing industry. This manuscript investigates the effect of cooling processes on the hardness, toughness, coefficient of friction, and wear rate of mild steel heat treated at different temperatures. The material was heat treated in a furnace at two different temperatures (500 and 900°C) and cooled by water, oil, and air. Microhardness and impact tests were conducted using ASTM E384 and ASTM E23-12C. For dry conditions, the tribology ASTM G99 test standard was used to determine the coefficient of friction and wear rate per sample. The results show that mild steel heat treated at 900°C and cooled with water increased the material’s hardness by 24% and toughness by 23.3% as compared to oil- and air-cooling media. The same heating temperature and water-cooling media produce the material with a low wear rate (3.223E-008).

Mechanical properties of polymer biocomposites are influenced by the interaction between the matrix and the filler surface. In this work, composites based on poly(butylene-adipate-terephthalate) (PBAT) filled with micrometric particles of zein-TiO₂ complex (ZTC) were realized via solvent casting technique at different concentrations, equal to 0, 5, 10, and 20 wt%. After pelletization, the resulting materials were injection molded into standard specimens, employed for the uniaxial tensile test (UTT) characterization. From the stress-strain curves, Young’s modulus (E), yield stress (σ_y), stress at break (σ_B), elongation at break (ε_B), and toughness (T) were collected. The addition of the ZTC proved to show a reinforcing effect on the polymeric matrix, with an increase in both E and σ_y. Modelling of the mechanical properties was performed by applying Kerner’s and Pukánszky’s equations. Kerner’s model, applied on experimental E values, returned a very good correspondence between collected and theoretical values. From the application of Pukánszky’s model to σ_y, the obtained B value showed a good interfacial interaction between the matrix and the filler. Due to the enhanced stiffness of the composites, a reduction in the true stress at break (σ_T,B) was observed. The modified Pukánszky’s model gave a B value lower than the one obtained for the yield, but still in the range of acceptable values for microcomposites.

In this study, the static deflection of non-prismatic axial function graded tapered beam (A-FGB) under distribution load has been analyzed using ANSYS workbench (17.2). According to a power-law model, the elastic modulus of the beam varies continuously in the axial direction of the beam. Also, the beam’s geometry, i.e., width, thickness, or both width and thickness of the beam, varies linearly in the axial direction with different values of non-uniformity parameter (1, 0.5,0, −0.5, and −0.75). The effects of martial distribution, i.e., power-law index, and non-uniformity parameter on the static deflection for A-FGB with different boundary conditions, in such free-clamped, clamped-free, and simply-supported, are studied. This research deals with functionally graded materials FGMs in more than one aspect in terms of using different boundary conditions; in addition, it studies the response of the non-prismatic beam non-uniformity parameter (α); therefore, this research studies comprehensively the deflection of the beam. The results show that the increase in power-law index causes decreasing in dimensionless deflection and its rate of change depends on the supporting types of the beam and non-uniformity parameters. The variation in both width and thickness for a free-clamped axial function–graded beam gives a significant decrease in dimensionless deflection at decreasing in non-uniformity parameter, whereas the variation in thickness for clamped-free axial function graded beam gives a significant decrease in dimensionless deflection at decreasing of non-uniformity parameter.

Friction stir welding is a method used to weld together materials considered challenging by fusion welding. FSW is primarily a solid phase method that has been proven efficient due to its ability to manufacture low-cost, low-distortion welds. The quality of weld and stresses can be determined by calculating the amount of heat transferred. Recently, many researchers have developed algorithms to optimize manufacturing techniques. These machine learning techniques have been applied to FSW, which allows it to predict the defect before its occurrence. ML methods such as the adaptive neurofuzzy interference system, regression model, support vector machine, and artificial neural networks were studied to predict the error percentage for the friction stir welding technique. This article examines machine learning applications in FSW by utilizing an artificial neural network (ANN) to control fracture failure and a convolutional neural network (CNN) to detect faults. The ultimate tensile strength is predicted using a regression and classification model, a decision tree model, a support vector machine for defecting classification, and Gaussian process regression (UTS). Machine learning implementation mainly promotes uniformity in the process and precision and maximally averts human error and involvement.

Being able to properly predict gear failure is a key aspect to achieve a reliable light-weight gearbox. Among the several gear failures, tooth root bending fatigue is considered as the most dangerous one because it implies the stoppage of the whole gearbox. In order to characterize a gear for this phenomena, Single Tooth Bending Fatigue (STBF) tests are the most performed ones. However, as in STBF test THERE IS no sliding/rolling contact and as the specimens are teeth rather than gears, some differences occur between the test conditions and those of the real case. This paper deals with the statistical ones that is the estimation of the gear SN curve starting from the teeth one. The teeth SN curve has been estimated by means of a statistical model developed considering Murakami’s idea of nonpropagating crack. Then, a methodology based on statistic of extreme is adopted for the purpose of estimating the gear SN curve.

Statistics of extreme values (SEV) and generalized Pareto distribution (GPD) are adopted to predict the maximum inclusion size in 40Cr structural steel, and the fatigue strength was estimated according to the obtained maximum inclusion size. The estimated results were compared with the experimental results obtained in rotating bending fatigue testing, where all failure-relevant inclusions of the present study were quantitatively analyzed with respect to $$ (square root of the projected inclusion area). Both the estimation results are consistent with the experimental results. Furthermore, a suitable maximum inclusion size equal to the prior austenite grain size is proposed for the material manufacturing process.

AISI 4130 steels have been used in several engineering applications, although presenting limited hardenability in conventional heat treatments. This contribution is aimed at determining the final hardness and reciprocating wear coefficient of friction (COF) after a given laser surface treatment (LST) with or without a carbon coating (C). The results indicated that the bare (B, without coating) condition produced a deeper case depth as a result of the carbon-rich plasma shielding. The observed microstructural features in the cases B and C showed martensite transformation and cementite formation; the latter is entirely in the C condition. Simple calculations using Rosenthal’s formalism indicate a high cooling rate, estimated as 32 ^′280°C/s 40 μm below the irradiated surface and a heat-affected zone bounded by the austenite locus. The hardness near to the surface was higher in case C than in case B, but the overall final hardness is more pronounced when the surface is bare (B) due to plasma shielding. On the other hand, the final COF was very low in the C case (0.1) compared to the B condition (0.6).

Scintillators with high light yield (LY) values are of interest for medical imaging applications, in harsh environments, nondestructive testing (NDT), etc. CeBr₃ has a LY of 60000 photons per MeV, a value much higher than other efficient materials, such as Lu₃Al₅O₁₂:Ce (25000 photons/MeV); thus, its X-ray detection properties would be of interest to be examined for medical imaging applications. The X-ray detection and absorption properties of a single crystal CeBr₃ sample along with the compatibility of its produced light with various optoelectronic sensors were examined. In this study, the quantum detection (QDE) and the energy absorption efficiency (EAE) of CeBr₃ were calculated. The findings were compared with data for 10 × 10 × 10 mm³ Lu₃Al₅O₁₂:Ce and CaF₂:Eu single crystals. The measured optical spectrum produced by CeBr₃ was well correlated with the spectral response of commercial optical sensors, yielding spectral matching higher than 93% for various photocathodes, e.g., GaAs (94%), E-S20 (95%), and bialkali and multialkali (95-97%), as well as with flat panel position-sensitive photomultipliers (95-99%). The energy absorption properties of CeBr₃ were found higher than those of Lu₃Al₅O₁₂:Ce and CaF₂:Eu for X-ray tube voltages greater than 100 kVp. The quantum detection efficiency was 100% across the examined energy range. Even though CeBr₃ is hygroscopic and has a mediocre 5.1 g/cm³ density, the QDE, EAE, and spectral correlation results are promising for medical imaging applications.

Fatigue life estimation of Ti-6Al-4V parts produced by additive manufacturing (AM) technologies has received increasing interest during the last decade. Recent studies focused mostly on the fatigue performance of Ti-6Al-4V considering a fixed stress ratio (R), usually 0.1 or −1. However, in order to properly design structural components subjected to variable loads, the effect of different stress ratios on the fatigue performance has to be carefully investigated. This research studies the stress ratio influence on the fatigue properties of Ti-6Al-4V specimens produced by laser powder bed fusion (L-PBF). Miniaturized Ti-6Al-4V samples were tested with the step procedure for different R values. A constant life Haigh's diagram (2 · 10⁶ cycles) was generated for L-PBF Ti-6Al-4V in as-built, electro-polished, and machined surface condition. The results present for the first time the relations between alternating and mean stresses for L-PBF Ti-6Al-4V with a fine α + β microstructure when different surface posttreatments are used to enhance the coupons’ final surface quality.

The employment of hybrid materials is frequently a solution for applications demanding high structural performances. FMLs (Fibre Metal Laminates) represent a group of hybrid materials, composed of metal sheets and composite material layers, and they exhibit good mechanical properties due to the presence of both types of material. The aim of this article is to introduce an FEM numerical model suitable for the prediction of the flexural behaviour of aluminium sheets/carbon fibre composite FMLs. Particular attention was paid to the simulation of the interface between the metal and the composite material. Therefore, the model for the three-point bending loading of two types of specimens was prepared: a specimen type presented a structural adhesive at the interface, while the other one was bonded by using the resin of the composite material. Experimental tests were carried out to validate the numerical model, and both the obtained load-displacement curves and the failure characteristics were compared with the results of numerical simulation. The appropriateness of the proposed model was witnessed by the correspondence between experimental and numerical results.