Search Results (6)

The electrochemical behavior and corrosion fatigue property of the surface-strengthened EA4T axle steel subjected to foreign object damage (FOD) is investigated in this study. It is found that the corrosion resistance can be enhanced after being impacted by the foreign object due to the introduced hardening layer. Specifically, compared to the smoothed sample, the 167 m/s sample exhibited a 13.88% higher corrosion potential (E_corr) and a 67.61% lower current density (i_corr). The facture surface demonstrates that the corrosion pits on the surface are the main crack initiation location for the smoothed specimens. In contrast, for the surface-damaged specimens, cracks initiate around the crater. The foreign object impact speed has a significant influence on the corrosion fatigue strength; specifically, the faster the impact velocity, the greater the surface damage of the axle specimen, and the shorter its fatigue life at the same stress level. To address the combined influence of size effect and surface defects on fatigue performance, we constructed an improved Kitagawa–Takahashi (KT) diagram by incorporating the theoretical corrosion fatigue limit of full-scale axles with a surface damage of 270 MPa based on conditional probability density function (CPDF). Comparative analysis demonstrates that the revised KT diagram defines a narrower yet more conservative fatigue loading safety zone than the standard KT diagram. This refinement enhances reliability in practical applications where surface imperfections and scale effects dominate failure mechanisms. Full article

Background: Biologics is an exciting and growing area of medicine. Within the larger field of biologics, the use of viral vectors and virus-like particles (VLPs) is increasingly common, making it crucial to develop innovative and practical unit operations for the related purification process. Objective: Some scientists and engineers propose that membrane-based downstream virus purification (MVP) platforms would allow for more scalable and cost-effective production of these critical particles. However, the so-cial, political, and ethical implications of these advancements remain largely unex-plored. This paper aims to explore various pivotal facets of MVP technology govern-ance and regulations within the U.S. context, including (1) government policy ar-rangements related to the implementation of the technologies, (2) stakeholder atti-tudes, policy preferences, and behaviors, and (3) the fundamental factors that shape these attitudes, policy preferences, and behaviors. Methods: In doing so, we analyze publicly available federal and state government documents pertaining to biomanu-facturing, healthcare, and legislative attempts. Additionally, we will perform a stake-holder analysis on relevant industries, healthcare service providers, and recipients. Conclusions: Our goal is to outline the socio-political, ethical, and regulatory factors pertaining to the regulation and governance of these technologies. Full article

Naturally fractured reservoirs are indescribable systems to characterize and difficult to produce and forecast. For the development of such reservoirs, the role of naturally forming fractures in the different development stages needs to be recognized, especially for the pressure maintenance and enhanced oil recovery stages. Recent development in the field of naturally carbonate fractured aimed at fracture characterization, fracture modeling, and fracture network impact of fracture networks on oil recovery were reviewed. Consequently, fracture identification and characterization played pivotal roles in understanding production mechanisms by integrating multiple geosciences sources and reservoir engineering data. In addition, a realistic fracture modeling approach, such as a hybrid, can provide a more accurate representation of the behavior of the fracture and, hence, a more realistic reservoir model for reservoir production and management. In this respect, the influence of different fracture types present in the reservoir, such as major, medium, minor, and hairline fractures networks, and their orientations were found to have different rules and impacts on oil production in the primary, secondary, and EOR stages. In addition, any simplification or homogenization of the fracture types might end in over or underestimating the oil recovery. Improved fracture network modeling requires numerous considerations, such as data collection, facture characterization, reservoir simulation, model calibration, and model updating based on newly acquired field data are essential for improved fracture network description. Hence, integrating multiple techniques and data sources is recommended for obtaining a reliable reservoir model for optimizing the primary and enhanced oil recovery methods. Full article

Bamboo is known as a typical kind of functional gradient natural composite. In this paper, fiber bundles were extracted manually from various parts of the stem in the radial direction, namely the outer, middle, and inner parts. After heat treatment, the mechanical properties of the fiber bundles were studied, including the tensile strength, elastic modulus, and fracture modes. The micromechanical properties of the fiber cell walls were also analyzed. The results showed that the mean tensile strength of the bamboo fiber bundles decreased from 423.29 to 191.61 MPa and the modulus of elasticity increased from 21.29 GPa to 27.43 GPa with the increase in temperature. The elastic modulus and hardness of the fiber cell walls showed a positive correlation with temperature, with the modulus of elasticity and the hardness increasing from 15.96 to 18.70 GPa and 0.36 to 0.47 GPa, respectively. From the outside to the inside of the bamboo stems, the tensile strength and elastic modulus showed a slight decrease. The fracture behavior of the fiber bundles near the outside approximates ductile fracture, while that of the bundles near to the inside tend to be a brittle fracture. The fracture surfaces of the bamboo bundles and the single fibers became smoother after heat treatment. The results show that bamboo fiber bundles distributed near the outside are most suitable for industrial development under heat treatment at 180 °C. Therefore, this study can provide a reasonable scientific basis for the selective utilization, functional optimization, and bionic utilization of bamboo materials, which has very important theoretical and practical significance. Full article

In a casing-cement sheath-formation system, the cement–formation interface is usually weakly cemented for the residual of drilling mud, in which a leakage path would easily form, threatening the safe operation of underground energy exploitation and storage. To evaluate the compressive and shear mechanical behavior of the cement–formation interface, cement–rock composite cylindrical specimens were prepared. Uniaxial and triaxial compression and direct shear tests were implemented. The flushing efficiency of the rock surface, compressive strength, interface incompatible deformation, parameters of shear strength, and morphology of shear failure surface were acquired and analyzed. Results show that the flushing efficiency of shale surface decreases from 76.7% to 64.2% with the surface roughness increasing from 0 to 2 mm. The flushing efficiency of sandstone is only 44.7%, remarkably lower than that of shale. With the stress condition transforming from uniaxial to triaxial compression, the feature of the stress–strain curves changes from elastic-brittle to elastoplastic, and the compressive strength increases from 20.6~60.1 MPa to 110~120 MPa. The cement part presents noteworthy plastic deformation and several micro shear fractures develop. There is incompatible deformation between cement and rock, which induces interface debonding for almost all the composite specimens. The internal friction angle and cohesive strength both decrease with the increase in pollution degree of drilling mud, and increase with the rise in surface roughness. The shear facture surface is not exactly the rock–cement interface, but usually manifests as a shear zone, in which the rock, cement, and interface all contribute to the final shear failure. The above findings would be valuable for the revealing of cement–formation interface failure mechanism. Full article

Hot compressive deformation behaviors of a powder metallurgy Ti-45Al-5Nb-0.4W/2Nb (at. %) were investigated at strain rates from 0.001 s⁻¹ to 1 s⁻¹ and temperatures from 1050 °C to 1200 °C. The Zener-Hollomon (Z) parameter can affect the hot deformation mechanism significantly. At a high Z condition, Nb particles played an important role in coordinating the deformation. At a low Z condition, deformation of Nb particles accompanied by dynamic recrystallization (DRX) can act as a dominant softening mechanism. The as-forged pancake exhibits a short rod-like particle-toughened equiaxed matrix. For notched three-point bending (3PB) tests, the fracture toughness of an Nb-particles-toughened high-Nb-containing duplex phase γ-TiAl alloy was hardly affected by the loading rate, presenting a peak fracture toughness of about 12.9 MPa·m^1/2. The toughness of the present alloy can be improved by ductile Nb particles. A model based on the Griffith-Orowan-Irwin relation was constructed, which is quite accurate to predict the facture toughness of the present specimen using tensile properties. Full article