The lightweight refractory high entropy alloys (RHEAs) can be considered the best alternative to Ni-based superalloys, which has significantly increased the attention of researchers. In this study, the newly designed lightweight (ρ ∼ 6.2 g/cm3) Al0.5Ti2Nb1Zr1WX (X: 0, 0.3, 0.5, 0.7) RHEAs were prepared. Our results evidence that the microstructure of Al0.5Ti2Nb1Zr1W0.5 RHEA has a BCC structure merged with B2 nano-precipitates, which leads to significant improvement in the specific yield strength (SYS) compared with other RHEAs. Besides, the compressive SYS (σ0.2/ρ) of Al0.5Ti2Nb1Zr1W0.5 RHEA

The geometric spacing and operating Reynolds number (Re) for the best thermal performance of square pin-fin heat sinks is found numerically at a Prandtl number of 0.7. The numerical model used is the double population thermal Multiple-Relaxation-Time Lattice Boltzmann Method (MRT LBM). The Nusselt number (Nu), friction factor (f) and the Thermal Performance Factor (TPF) are calculated for a range of streamwise (0.5 to 3) and cross-streamwise (1 to 2) spacing ratios at Re numbers from 20 to 140. A quadratic thermal equilibrium distribution function is used instead of the commonly used linear

The flow inside a solid rocket motor is considered taking into account the fluid-solid interaction between the combustion gases and the burning grain surface. An unsteady flow model is presented for the flow variables while the time-dependent burning surface is captured using the level set method. Then, a hybrid model is presented by coupling the flow model with the interface capturing technique. The proposed hybrid model is successfully tested against previously published experimental and numerical data. The use of the level set method enables the flow model to consider complex grain shapes

The Al–Zn–Mg–Cu 7055 aluminum alloy was meticulously fabricated through spray forming (SF) technology, followed by hot extrusion and T76 treatment. This comprehensive process allowed for a thorough investigation of its microstructural characteristics, mechanical properties, and fatigue behavior. Post-treatment analysis revealed that the SF-7055 aluminum alloy exhibited no notable segregation or porosity defects, ensuring its exceptional quality and reliability. The microstructural analysis revealed a uniform distribution of refined grains and dispersed precipitates, contributing to the

The aerodynamic performance of a moving flapping wing is investigated numerically using a fluid–solid interaction model. The flow field is assumed to be two-dimensional, viscous, unsteady, and incompressible. Galerkin-least/squares finite element method is used to account for the convective nature of the flow field. The flow solver is coupled with the rigid body equations of motion describing the movement of the flapping wing. An interface-capturing technique is developed and tailored to the present model to capture the flapping wing during its movement. The developed algorithm is validated

Robot dynamic modeling and parameter identification are essential for many analyses. High-fidelity multi-body dynamics simulators can model the robot's dynamic behavior, but they can't identify the robot's non-linear dynamic model needed for controller design. This study proposes a three-step machine-learning framework for extracting the dynamic equations of serial manipulators from data. This framework consists of three steps. Initially, a library of candidate functions is constructed, together with a data set based on the robot's unforced response. Secondly, the best models that can

Reinforced concrete (RC) walls are commonly used in various structures to resist lateral forces. In the current paper, hybrid usage of stainless steel (SS) and glass fiber-reinforced polymer (GFRP) as an alternative of steel rebars, which is susceptible to corrosion, is proposed to improve durability of RC walls. Due to the high cost of SS compared to GFRP, SS rebars are utilized as concentrated reinforcement (RFT) in plastic hinge regions while GFRP rebars are used elsewhere. This combination has the advantage of providing adequate ductility and strength needed to resist both gravity and

Abstract: Careful design of the high-tech semi-circular breakwaters (SBW), which are used for protection against sea waves, is essential to avoid the failure of these large-scale projects. An improved design tool adopting numerical simulations, complemented with experimental measurements is introduced. Unstructured boundary-fitted grids are used to model the curved SBW boundary accurately and resolve the flow adjacent to it. Experimental measurements based on Particle Image Velocimetry (PIV) are introduced and the numerically simulated velocity fields are validated. For the first time, the

A square cylinder may gallop if subjected to fluid flow, experiencing a self-excited vibration mode that can harvest energy for low-power applications. The harvested power is typically low and depends on the upstream flow velocity and system dynamic parameters. In this study, the influence of nonlinear stiffness induced by two repulsive magnetic poles on the galloping response of square rods is investigated at a mass ratio of 10 and a Reynolds number of 200. The vibration response of two identical coaxial square rods with magnetic poles attached to their opposite ends is analyzed. Two

Water hyacinth has become widespread in freshwater bodies in several countries, leading to various issues, particularly its substantial water consumption and the resulting need to control its growth. Among the different methods of controlling water hyacinth, mechanical control stands out as the most effective and environmentally friendly approach. A proposed harvester robot has been developed, capable of efficiently cutting and collecting water hyacinth from the water's surface. The robot boasts several advantages, including its ability to operate in narrow water paths and lakes, use clean