A test device was developed to meticulously assess chloride corrosion damage in unsaturated concrete structures experiencing repeated loading cycles. The experimental data, indicating the impact of repeated loading on moisture and chloride diffusion coefficients, formed the basis for a chloride transport model for unsaturated concrete under combined repeated uniaxial compressive loading and corrosion. The chloride concentration beneath combined loading was quantified via the Crank-Nicolson finite difference method and the Thomas algorithm. This facilitated the analysis of chloride transport under concurrent repeated loading and corrosion. As indicated by the results, the relative volumetric water content and chloride concentration within unsaturated concrete are directly affected by both the stress level and the number of repeated loading cycles. Unsaturated concrete experiences a more significant effect from chloride corrosion than saturated concrete.
In comparing the effects of conventional solidification (homogenized AZ31) and rapid solidification (RS AZ31) on the microstructure, texture, and mechanical properties, this study utilized a commercially available AZ31B magnesium alloy. The rapid solidification of the microstructure is shown to enhance performance following hot extrusion, using a moderate extrusion rate of 6 meters per minute and a temperature of 250 degrees Celsius. The extruded AZ31 rod, homogenized and then annealed, displays an average grain size of 100 micrometers; after extrusion, it is 46 micrometers. Conversely, the as-received AZ31 extruded rod exhibits a substantially smaller grain size of only 5 micrometers after annealing and 11 micrometers after extrusion. An average yield strength of 2896 MPa is demonstrated by the as-received AZ31 extruded rod, exceeding the as-homogenized extruded rod by a substantial 813%. The extruded AZ31 as-RS rod showcases a more random crystallographic orientation and a peculiar, weak texture component, evident in its //ED.
An analysis of the bending load characteristics and springback during three-point bending of 10 and 20 mm thick AW-2024 aluminium alloy sheets with rolled AW-1050A cladding is presented in this article. Formulated specifically to establish the bending angle as a function of deflection, a proprietary equation was introduced, considering the tool's radius and the sheet material thickness. Numerical modeling results for springback and bending loads, using five distinct models, were compared to experimental data. Model I, a 2D plane strain model, excluded clad layer material properties. Model II, also 2D plane strain, included those properties. Model III, a 3D shell model, used the Huber-von Mises isotropic plasticity condition. Model IV, a similar 3D shell model, used the Hill anisotropic plasticity condition. Model V, a third 3D shell model, utilized the Barlat anisotropic plasticity approach. The five tested finite element models' accuracy in predicting the bending load and springback characteristics was highlighted. Regarding bending load prediction, Model II outperformed all others, while Model III demonstrated superior predictive ability for the amount of springback after bending.
This study investigated the influence of flank wear on the microstructure characteristics of the metamorphic layer, recognizing the significant impact of the flank on the workpiece's surface and the critical role of microstructure flaws in the surface metamorphic layer regarding component service performance, all under high-pressure cooling. The simulation modeling software, Third Wave AdvantEdge, was utilized to model the cutting of GH4169, using tools that demonstrated varied flank wear values, in a high-pressure cooling environment. The simulation results highlighted how flank wear width (VB) influenced cutting force, cutting temperature, plastic strain, and strain rate. To further investigate, an experimental platform was built to perform high-pressure, cool cutting on GH4169, enabling the real-time recording and comparison of cutting force data with simulated results. Medical Abortion Ultimately, an optical microscope was employed to examine the metallographic microstructure of the GH4169 specimen's cross-section. Microstructural features of the workpiece were elucidated by the combined use of a scanning electron microscope (SEM) and electron backscattered diffraction (EBSD). A concomitant rise in cutting force, cutting temperature, plastic strain, strain rate, and plastic deformation depth was observed with increasing flank wear width. Discrepancies between the simulated and experimental cutting force measurements remained within the 15% relative error band. A metamorphic layer, with indistinct grain boundaries and a refined grain structure, was situated near the surface of the workpiece. Greater flank wear width correlated with a rise in the thickness of the metamorphic layer, transitioning from 45 meters to 87 meters, and with an increase in grain refinement. The strain rate's intensity promoted recrystallization, which induced an increase in the average grain boundary misorientation, an increase in the frequency of high-angle grain boundaries, and a decrease in twin boundaries.
Various industrial fields depend on FBG sensors to assess the structural integrity of mechanical parts. Whether the conditions are extremely high or extremely low, the FBG sensor is effectively applicable. To ensure the stability of the FBG sensor's reflected spectrum and mechanical integrity in harsh temperature conditions, metal coatings are employed to safeguard the grating. At elevated temperatures, nickel (Ni) stands out as a promising coating material for enhancing the performance characteristics of fiber Bragg grating (FBG) sensors. Moreover, the research demonstrated the potential of Ni coating and high-temperature treatments to restore the functionality of a fractured, seemingly unusable sensor unit. This study aimed to first optimize coating parameters for maximal compactness, adhesion, and uniformity, and second, to link the resulting morphology and structure with the altered FBG spectrum after nickel deposition on the sensor. Using aqueous solutions, a Ni coating was deposited. Through the application of heat treatments to the Ni-coated FBG sensor, an investigation was undertaken into how the wavelength (WL) changed in response to temperature fluctuations, and the underlying mechanism relating this variation to structural or dimensional alterations within the Ni coating.
This paper's research investigates the use of a rapidly reacting SBS polymer to modify asphalt bitumen at a low modifier percentage. The proposition is that a swiftly responsive styrene-butadiene-styrene (SBS) polymer, comprising only 2% to 3% of the bitumen's weight, could potentially prolong the service life and performance of pavement surfaces at a relatively modest investment, thereby enhancing the net present value of the pavement throughout its operational lifespan. The aim of confirming or refuting this hypothesis involved modifying two types of road bitumen, CA 35/50 and 50/70, with small quantities of fast-reacting SBS polymer, in an effort to achieve properties similar to a 10/40-65 modified bitumen. Tests including needle penetration, softening point (ring and ball), and ductility were conducted on unmodified bitumen, bitumen modification, and 10/40-65 modified bitumen specimens of each type. The second section of the article analyzes the comparative properties of asphalt mixtures, showcasing the impact of different coarse-grain curve compositions. The Wohler diagram showcases the complex modulus and temperature-dependent fatigue resistance, presented separately for each constituent mixture. Biomagnification factor Pavement performance after modification is determined through laboratory impact evaluations. The life cycle changes for each type of modified and unmodified mixture are measured in terms of road user costs, and these costs are compared to the increased construction costs to evaluate the benefits.
This research paper presents the outcome of a study concerning a newly developed surface layer created by laser remelting the working surface of the Cu-ETP (CW004A, Electrolytic Tough Pitch) copper section insulator guide, incorporating Cr-Al powder. The investigation employed a fibre laser, specifically one with relatively high power reaching 4 kW, to guarantee a high gradient of cooling rate, thereby optimizing microstructure refinement. An investigation into the microstructure of the transverse fracture within the layer (SEM) and the distribution of elements within the micro-regions using energy-dispersive X-ray spectroscopy (EDS) was performed. The copper matrix, as evidenced by the test results, proved incapable of dissolving chromium, leading to the formation of precipitates that assumed a dendritic shape. The following aspects were examined: the hardness and thickness of surface layers, the friction coefficient, and how the Cr-Al powder feeding speed impacted these parameters. Coatings manufactured at a distance of 0.045 mm from the surface surpass 100 HV03 in hardness, exhibiting a friction coefficient in the interval of 0.06 to 0.095. learn more Further, more sophisticated investigations pinpoint the d-spacing lattice parameters of the obtained Cu crystal structure, situated in the interval between 3613 and 3624 Angstroms.
The diverse wear mechanisms exhibited by various hard coatings have been elucidated through extensive application of microscale abrasion studies. A study was recently published that explored whether the ball's surface texture could influence the way abrasive particles move when in contact. This investigation aimed to clarify the connection between abrasive particle concentration and the texture of the ball, subsequently influencing the wear mechanisms observed, which were either rolling or grooving. Accordingly, experiments were carried out on specimens coated with a thin layer of TiN, produced by the Physical Vapor Deposition (PVD) method, with AISI 52100 steel balls etched for sixty seconds, thus altering their surface texture and roughness.