Novel AZ91 magnesium syntactic foams are a potential choice for temporary biomedical implants.In this study, the drilling performance of biodegradable grade AZ91-magnesium foam is investigated under different lubrication methods. Drilling experiments were carried out using titanium aluminium nitride (TiAlN) (PVD) coated and uncoated twist drills on varying volume fractions of AZ91 magnesium syntactic foams (5%, 10%, and 15%) reinforced with hollow alumina microspheres. Test results showed a 30%-60% higher thrust forces generated with cryogenic machining. while cutting AZ91-15% hollow alumina foam. Higher volume fraction syntactic foam recorded higher machining forces, which increased by almost 200% as the volume fraction of hollow alumina increased from 5% to 15% during dry machining.A three-dimensional, thermo-mechanical finite element-based model for drilling magnesium syntactic foam using AdvantEdgeTM is presented for different lubrication conditions. Based on the analysis carried out, cryogenic machining is recommended as a sustainable drilling process for AZ91-magnesium syntactic foams.
The influence of independent process variables of Pulsed metal inert gas welding (P-MIG) such as current, weld speed, and wire feed speed for welding dissimilar metals stainless steel 304 and mild steel were examined. The L9 Taguchi array was used to optimize the input parameters with the necessary quality factors being ultimate tensile strength (UTS), and mass deposition rate (MDR). The Taguchi approach and Grey relational analysis have been used to optimize and identify the best P-MIG process parameters. Taguchi Desirability tests were used to interpret, explore, and evaluate the experimental results from UTS, and MDR. To determine the effect of each variable, ANOVA has been used. Wire feed rate and weld current were found to be the most contributing variables, while weld speed was the least important. Bending distortion and buckling are observed on the weld plate and detailed analysis of distortion will be done in the future.
CO2 capture is not only important to reduce CO2 footprints, but also it can be attractive for enhanced oil recovery. However, costs for CO2 capture are still expensive. Rotating packed beds can intensify the capture process using HiGee technology, cutting down capture costs. In this study, the dry pressure drop is validated and compared against three modified geometric designs. Pressure-drop at free rotational zone exhibits comparable value to the packing. However, modifying the area design at the packing's inner edge shows a reduction in total pressure drop by 30%. This accounts for a 36 to 46 % reduction in free rotational zone pressure drop. As a result, this can save 30% of compression power.
Most studies of phononic crystals (PnC) mainly focus on creating mechanical properties contrast between two phases in a unit cell. However, large contrast in dimension and configuration of different components of the same phase could also induce wide phononic band gap. In our research, simple cubic (SC) lattice on mesoscopic scale is studied and two groups of eigenmode (bulk-mode and interaction mode) are found to be the reason for the opening of Phononic band gap.
Complex and lightweight lattice-based structures could be manufactured using Additive manufacturing (AM) processes. Triply periodic minimal surfaces (TPMS) are cellular structures with mathematically defined architectures in which surface area for a given boundary is locally minimized. Material usage, cost and part weight could be optimized by combining additive manufacturing with TPMS structures. This paper introduces a methodology for generating variable density TPMS lattice structure by mapping the output of topology optimization. As an example, the proposed methodology is implemented for structural and heat conduction optimization problem
An experimental investigation on a horizontal hydraulic loop with a transparent test zone is employed to study the interaction of a circular bluff body with a two-phase swirl flow. Using high speed camera the gaseous phase is analyzed. The air core is studied with instantaneous and average images. Which are then processed using Matlab image processing toolbox to capture some relevant information about the air core for different Gas-Liquid Ratio (GLR) in steady state. Further information addressing the interaction with the circular bluff body is embodied on a flow regime map is also reported.
This paper intends to describe the process of derivation of loading surfaces with respect to phase transformation, when a structure is subjected to cyclic loading. This structure is realized as a Schwartz Primitive unit cell, and appropriate boundary conditions are applied to simulate the presence of adjacent unit cells. One hypothesis is that the curves in a stress space will shrink as more cycles are performed, due to a higher martensite volume fraction. This is a consequence of functional fatigue.
We analyzed the low Reynolds number (Re=100) flow generated behind a slitted 2D cross-sectional cylinder placed in a stream flow and oriented at various azimuth angles, to explore the possibility of passive control of the incompressible laminar boundary layer. Experiments were conducted using a 2D soap film tunnel that we have setup in our laboratory at Khalifa University. The visualization in soap film tunnel exploits the optical properties of soap film and relies on the wake formation patterns and the vortices shedding frequencies. These flow visualizations of the vortex shedding behind the cylinder with/without slit were recorded and analyzed and can be used to validate the 2D numerical simulations of similar flow. The developed soap-film technique will be attempted over more complex 2D shapes subjected to other controls for CFD validation. We will provide the details of the soap-film technique and guidelines for successful experimentation demonstrated on slitted cylinder.
The topic of Supernumerary Robotic Limbs (SRLs) has become of great interest in recent years. Researchers from all around the world have been involved in the analysis and development of the extra robotic limbs. This is of no surprise as SRLs can be used in many applications, especially in the industrial field where they can be used to reduce workers' fatigue and offer them help in different demanding tasks. However, there are many challenges in all the stages of this development process. Many factors should be considered and optimized such as weight, wearability, and Safety; which is the most critical factor. In this paper, the mechanical design and workspace analysis of an extra robotic arm will be presented and discussed. Also, future work will be included at the end.
To reduce equipment size and enhance mass transfer, Process Intensification (PI) technologies are extensively used. Mass transfer plays an important role in heterogeneous reactor systems where chemical species must interact with the catalytic surface. As part of this study, a heterogeneous reactor system, the Rotating Bed Reactor (RBR), is modeled using computational fluid dynamic (CFD) tool ANSYS. Two different geometries are used to investigate the flow characteristics, i.e., a detailed geometrical model involving a quarter (90o segment) of the reactor and a simplified geometrical model employing a 22.5o segment of the whole reactor. The CFD models are validated using a previous study. It is found that the pressure and velocity profiles computed using a simplified geometrical model are in close agreement with the model based on detailed geometry. Further, it is shown that the simplified model required less computational power and can be used for further studies.
