The present work seeks to offer a concise summary of analytical solutions for characterizing in-plane and out-of-plane stress fields in orthotropic solids with radiused notches. In pursuit of this aim, a starting point is established by briefly outlining the fundamentals of complex potentials in the context of orthotropic elasticity, in relation to plane stress/strain and antiplane shear. Later, the focus is on characterizing the essential expressions for the stress fields around notches, with consideration given to elliptical holes, symmetric hyperbolic notches, parabolic notches (representing blunt cracks), and radiused V-notches. Ultimately, the presented analytical solutions are evaluated through examples of applications, where they are compared to numerical results obtained from relevant instances.
This research introduced a novel, expedited procedure, StressLifeHCF. Fatigue life can be determined in a process-oriented manner by combining classic fatigue testing with non-destructive material monitoring during cyclic loading. The procedure mandates a total of two load increases and two constant amplitude tests. Data obtained via non-destructive measurement methods enabled the determination of both elastic parameters, based on Basquin's work, and plastic parameters, based on Manson-Coffin's model, which were then combined and used in the StressLifeHCF calculation. Moreover, two further iterations of the StressLifeHCF methodology were conceived to afford a precise depiction of the S-N curve across a more expansive spectrum. Among the subjects of this research, 20MnMoNi5-5 steel, a ferritic-bainitic steel, was identified by the code (16310). German nuclear power plants' spraylines prominently feature this specific type of steel. Additional tests on SAE 1045 steel (11191) were carried out to verify the results.
A structural steel substrate was coated with a Ni-based powder, consisting of NiSiB and 60% WC, via the combined application of laser cladding (LC) and plasma powder transferred arc welding (PPTAW). Analyzing and comparing the surface layers produced was a key part of the study. Both methods yielded secondary WC phase precipitation in the solidified matrix, with the PPTAW cladding demonstrating a dendritic microstructure. The microhardness of the clads, irrespective of the preparation method, was remarkably similar; however, the PPTAW clad demonstrated a greater resilience against abrasive wear than the LC clad. Both techniques resulted in a slender transition zone (TZ), with a noticeable coarse-grained heat-affected zone (CGHAZ) and macrosegregations shaped like peninsulas observed within the respective clads. The thermal cycles applied to the PPTAW clad material resulted in a unique cellular-dendritic growth solidification (CDGS), with a type-II boundary developing within the transition zone (TZ). Both methods successfully created metallurgical bonding of the clad to the substrate, but the LC process showcased a lower dilution coefficient. A larger heat-affected zone (HAZ), characterized by higher hardness, was also a consequence of the LC method, contrasted with the PPTAW clad's HAZ. This research indicates that both methods hold promise for use in anti-wear applications, stemming from their inherent wear resistance and the metallurgical bonding to the underlying material. PPTAW cladding's resilience to abrasive wear is a key strength in applications demanding such qualities, whereas the LC method is more suitable for applications prioritizing low dilution and a larger heat-affected zone.
The utility of polymer-matrix composites is substantial within the realm of engineering applications. Despite this, environmental influences significantly impact their macroscopic fatigue and creep resistance, originating from various mechanisms within the microstructure. This analysis considers the effects of water absorption, culminating in swelling and, eventually, hydrolysis with enough time and quantity. bioactive dyes The high salinity, high pressure, low temperature, and the presence of biotic life forms in seawater contribute to the acceleration of fatigue and creep damage. Other liquid corrosive agents, similar to the first, permeate cracks formed due to cyclic loading, thereby dissolving the resin and breaking the interfacial bonds. Exposure to ultraviolet radiation results in either increased crosslinking density or chain scission, thereby causing the surface layer of a particular matrix to become brittle. Temperature fluctuations near the glass transition negatively impact the fiber-matrix interface, leading to microcracking and compromising fatigue and creep resistance. Biopolymer breakdown by microbial and enzymatic means is examined, with microbes playing a key role in metabolizing specific substrates, impacting their microstructures and/or chemical components. The effects of these environmental factors on epoxy, vinyl ester, and polyester (thermosets), polypropylene, polyamide, and polyetheretherketone (thermoplastics), and polylactic acid, thermoplastic starch, and polyhydroxyalkanoates (biopolymers) are extensively documented. Environmental factors highlighted collectively impede fatigue and creep resistance, modifying the composite's mechanical attributes or inducing stress concentrations via micro-fractures, thereby accelerating failure. Further studies are needed, investigating materials other than epoxy, as well as developing standardized testing methods.
High-viscosity modified bitumen (HVMB)'s high viscosity makes standard, short-term aging methods unsuitable for evaluating its performance. Accordingly, the aim of this study is to introduce a relevant short-term aging strategy for HVMB, achieved through a heightened aging period and a rise in temperature. To achieve this objective, two types of commercial HVMB materials were subjected to aging via rolling thin-film oven testing (RTFOT) and thin-film oven testing (TFOT) at various durations and temperatures. Open-graded friction course (OGFC) mixtures, containing high-viscosity modified bitumen (HVMB), underwent aging through two schemes to represent the short-term aging of the bitumen at the mixing facility. Using temperature sweep, frequency sweep, and multiple stress creep recovery tests, the rheological characteristics of the short-term aged bitumen and the extracted bitumen were investigated. The rheological properties of TFOT- and RTFOT-aged bitumen, when compared to extracted bitumen, facilitated the determination of suitable laboratory short-term aging methods for high-viscosity modified bitumen (HVMB). The comparative results suggest that 2 hours of aging the OGFC blend in a 175°C forced-draft oven provides a suitable simulation of the short-term bitumen aging process at the mixing plant. TFOT proved more advantageous for HVMB compared to RTOFT. The aging period for TFOT, as recommended, is 5 hours, accompanied by a temperature of 178 degrees Celsius.
Using magnetron sputtering, silver-doped graphite-like carbon (Ag-GLC) coatings were fabricated on both aluminum alloy and single-crystal silicon, where the deposition conditions were adjusted to achieve varying results. An investigation into the influence of silver target current, deposition temperature, and CH4 gas flow on the spontaneous detachment of silver from GLC coatings was undertaken. Additionally, the resistance to corrosion was assessed for the Ag-GLC coatings. Regardless of the preparation conditions, the results unveiled the occurrence of spontaneous silver escape at the GLC coating. Environmental antibiotic The resultant size, number, and distribution of the escaped silver particles were demonstrably influenced by these three preparatory steps. Contrary to the influence of the silver target current and the addition of CH4 gas flow, the adjustment of the deposition temperature uniquely produced a meaningful enhancement in the corrosion resistance properties of the Ag-GLC coatings. When the Ag-GLC coating was deposited at 500°C, the best corrosion resistance was observed, this being attributable to a reduced number of silver particles that escaped from the coating as the temperature was increased.
In contrast to conventional rubber sealing, soldering based on metallurgical bonding is capable of achieving a firm seal for stainless-steel subway car bodies, though the corrosion resistance of such joins has received little attention. In this exploration, two widely used solders were employed in the soldering of stainless steel, and their qualities were assessed. As evidenced by the experimental outcomes, the two types of solder exhibited favorable wetting and spreading properties on stainless steel plates, ultimately achieving successful sealing connections between the stainless steel sheets. Unlike the Sn-Zn9 solder, the Sn-Sb8-Cu4 solder's solidus-liquidus point is lower, making it more appropriate for the application of low-temperature sealing brazing. Eribulin ic50 A sealing strength exceeding 35 MPa was observed in the two solders, a marked improvement over the current sealant, which has a strength below 10 MPa. In the corrosion process, the Sn-Zn9 solder had a stronger propensity for corrosion and a greater degree of corrosion compared to the Sn-Sb8-Cu4 solder.
Tools with indexable inserts are widely used for the purpose of material removal in modern manufacturing operations. Experimental insert shapes and, most significantly, internal structures like coolant channels, are now producible using additive manufacturing techniques. This study addresses the development of a process for the production of WC-Co pieces containing internal coolant conduits, aiming for an appropriate microstructure and surface finish, especially within the conduits. To begin this study, we analyze the process parameters required to achieve a microstructure that is free from cracks and possesses minimal porosity. The following stage prioritizes and focuses exclusively on the improvement of the parts' surface quality. Coolant flow is profoundly affected by the internal channels' surface area and quality, demanding careful evaluation of these characteristics. In conclusion, WC-Co specimens were successfully manufactured. The resulting microstructure displayed no cracks and low porosity; an optimal parameter set was discovered.