Effect of Processing Parameters on Recrystallization During Hot Isostatic Pressing of Stellite-6 Fabricated Using Laser Powder Bed Fusion Technique.

Crack-free Stellite-6 alloy was fabricated using the laser powder bed fusion technique equipped with a heating module as the first attempt. Single tracks were printed with a build plate heated to 400 °C to identify the processing window. Based on the melt pool dimensions, two combinations (sample A: 300 W/750 mm/s and sample B: 275 W/1000 mm/s) were identified to print the cubes.

Microstructures and Corrosion Properties of Wire Arc Additive Manufactured Copper-Nickel Alloys.

The 70/30 copper-nickel alloy is used mainly in critical parts with more demanding conditions in marine settings. There is a need for innovative methods that offer fast production and cost-effectiveness in order to supplement current copper-nickel alloy manufacturing processes. In this study, we employ wire arc additive manufacturing (WAAM) to fabricate the 70/30 copper-nickel alloy.

Unusually high room and elevated-temperature tensile properties observed in direct aged wire-arc directed energy deposited Inconel 718.

Wire-arc directed energy deposition (DED) processed Inconel (IN) 718 is known to have coarse columnar grains, strong texture, and significant chemical and microstructural inhomogeneity in the as-fabricated condition. Homogenization treatment is commonly used prior to aging to eliminate the inhomogeneity and detrimental precipitation for better mechanical properties. In this study, however, direct aging (DA) at 700 °C without homogenization has resulted in room-temperature yield strength, ultimate tensile strength (UTS), and elongation that are comparable to wrought condition and among the highest reported properties for wire-arc DED IN718.

Toward Real-Time Blood Pressure Monitoring via High-Fidelity Iontronic Tonometric Sensors with High Sensitivity and Large Dynamic Ranges.

Continuous, noninvasive blood pressure (CNIBP) monitoring provides valuable hemodynamic information that renders detection of the early onset of cardiovascular diseases. Wearable mechano-electric pressure sensors that mount on the skin are promising candidates for monitoring continuous blood pressure (BP) pulse waveforms due to their excellent conformability, simple sensing mechanisms, and convenient signal acquisition. However, it is challenging to acquire high-fidelity BP pulse waveforms since it requires highly sensitive sensors (sensitivity larger than 4 × 10 kPa ) that respond linearly with pressure change over a large dynamic range, covering the typical BP range (5-25 kPa).

Integrating Geometric Data into Topology Optimization via Neural Style Transfer.

This research proposes a novel topology optimization method using neural style transfer to simultaneously optimize both structural performance for a given loading condition and geometric similarity for a reference design. For the neural style transfer, the convolutional layers of a pre-trained neural network extract and quantify characteristic features from the reference and input designs for optimization. The optimization analysis is evaluated as a single weighted objective function with the ability for the user to control the influence of the neural style transfer with the structural performance.

Ultrahigh Thermal Rectification in Pillared Graphene Structure with Carbon Nanotube-Graphene Intramolecular Junctions.

In this letter, graded pillared graphene structures with carbon nanotube-graphene intramolecular junctions are demonstrated to exhibit ultrahigh thermal rectification. The designed graded two-stage pillared graphene structures are shown to have rectification values of 790.8 and 1173.

Proportional Topology Optimization: A New Non-Sensitivity Method for Solving Stress Constrained and Minimum Compliance Problems and Its Implementation in MATLAB.

A new topology optimization method called the Proportional Topology Optimization (PTO) is presented. As a non-sensitivity method, PTO is simple to understand, easy to implement, and is also efficient and accurate at the same time. It is implemented into two MATLAB programs to solve the stress constrained and minimum compliance problems.

Ultra-low Thermal Conductivity in Si/Ge Hierarchical Superlattice Nanowire.

Due to interfacial phonon scattering and nanoscale size effect, silicon/germanium (Si/Ge) superlattice nanowire (SNW) can have very low thermal conductivity, which is very attractive for thermoelectrics. In this paper, we demonstrate using molecular dynamics simulations that the already low thermal conductivity of Si/Ge SNW can be further reduced by introducing hierarchical structure to form Si/Ge hierarchical superlattice nanowire (H-SNW). The structural hierarchy introduces defects to disrupt the periodicity of regular SNW and scatters coherent phonons, which are the key contributors to thermal transport in regular SNW.

Carbon nanotube-fullerene hybrid nanostructures by C₆₀ bombardment: formation and mechanical behavior.

This study reports the investigation on C60 bombardment on the carbon nanotube (CNT) by molecular dynamic (MD) simulations. We found that carbon nanotube nanobuds or nanotube-fullerene hybrid nanostructures can be formed by C60 bombardment. Different from the nanobuds in earlier studies, more structural patterns are found in the bombardment formed nanobuds and nanotube-fullerene hybrid nanostructures.

Surface structure and properties of functionalized nanodiamonds: a first-principles study.

The goal of this work is to gain fundamental understanding of the surface and internal structure of functionalized detonation nanodiamonds (NDs) using quantum mechanics based density functional theory (DFT) calculations. The unique structure of ND assists in the binding of different functional groups to its surface which in turn facilitates binding with drug molecules. The ability to comprehensively model the surface properties, as well as drug-ND interactions during functionalization, is a challenge and is the problem of our interest.

Anomalous heat conduction behavior in thin finite-size silicon nanowires.

Anomalous heat conduction behavior is observed for the first time using non-equilibrium molecular dynamics (NEMD) simulations to obtain the thermal conductivity of thin finite-size silicon nanowires (NWs) in the 001 lattice direction. In the series of simulations, the length dependence of thermal conductivity of thin silicon nanowires (NWs) ranging from 6 to 434 nm is analyzed. It is found that a transition occurs in the thermal conductivity versus length curve after the initial convergence trend appears near the mean free path of bulk silicon.