The digital light processing (DLP) technique is utilized to manufacture CNT-based nanocomposites with different concentrations of multi-walled carbon nanotubes (MWCNTs). An optimization of resin development and additive manufacturing parameters was carried out to print the pristine and composite samples successfully. The prepared samples were tested for their mechanical properties and self-sensing capabilities to analyze the effect of the addition of CNTs in a polymeric matrix. A tensile test was carried out to evaluate the mechanical properties of pristine and nanocomposite samples. Electrical resistance data was collected while performing uniaxial tensile tests and used to compare the piezoresistive behavior of different nanocomposite specimens.
In this paper, an overview of the use of ionic liquids in 3rd generation solar cells is presented. Third generation photovoltaics are facile to prepare and their efficiencies to convert solar energy to electrical energy at a low cost is augmented every year. In particular, dye-sensitized solar cells, although not the proprietors of the highest efficiency among their 3rd generation peers, they come at a low cost and ease of production. However, they possess several disadvantages such as leakage and vaporization of electrolytes. The utilization of ionic liquids partially solves the issue of the stability and improves the performance of the solar cells at various electrolyte states.
The main challenge that hinders the use of lithium-ion batteries in space applications is their low performance at ultra-low temperatures. Such low performance is mostly due to the low ionic conductivity and freezing of the electrolyte leading to a significant loss in the battery's capacity. In this research, the behavior of a half-cell lithium-ion battery is investigated by employing electrochemical characterization techniques to study their performance at low temperatures. Based on the electrochemical behavior, the performance of half-cell batteries decreases rapidly at subzero temperatures in which it is completely degraded at -30 ℃. This study contributes to the development of Li-ion batteries for low temperature and space applications by understanding their electrochemical behavior.
This study was carried out to improve the strength of AA6061 Friction Stir Welded (FSW) joints by incorporating particulate reinforcements (B4C). Sheets of Al 6061 were welded by friction stir welding and the weld nugget was reinforced using B4C particles. The prepared weldment was characterized by field emission scanning electron microscope (FESEM) and optical microscopy for studying microstructural and electron dispersive spectroscopy (EDS) for elemental analysis. It was observed that the addition of reinforcement increased in the ultimate tensile strength and hardness of the welded area. Scanning electron micrographs were taken to observe the dispersion and changes occurred to the reinforcements during friction stir welding. Universal testing machine (UTM) was used to perform tensile testing and hardness will be performed on Vickers's hardness tester. Reinforced welds resulted in the increase in the strength of the Al alloy joint.
Polyurethane foam has many applications and can be used as a human skin substitute. Having an accurate numerical mechanical model can be useful in predicating of the behavior of the foam in its different applications. A uni-axial compression test, simple shear test and stress relaxation tests were conducted to capture the mechanical behavior of the foam. A 3rd order Hyperfoam model was fitted to data from the uni-axial compression test data and simple shear test data and the fit based on both data simultaneously was found to be better in terms of stability for uni-axial and shear behavior. Also, stress relaxation test was done and a 3rd order Prony series was fitted to it and the fitting was found to be representative of the test data.
This work aims to investigate the effect of incorporating zeolites with different Si/Al ratio as catalyst supports in hydrocracking processes. Heptane was hydrocracked in the presence of Ni-Zeolite type Y catalysts, Ni-ZY, having four different SiO2/Al2O3 ratios of 5, 30, 60, and 80. Nickel was added by wet impregnation method to the zeolites such that to get 5 wt. % of the metal in the catalyst, and then calcined in air at 500oC for 5 hours. Various characterization methods were used to study the structure, crystallinity, morphology, acidity, and reducibility of the catalysts, some of which are included in this short manuscript. The catalytic testing of the materials were done at two hydrocracking temperatures, 350 and 400oC.
The flow and heat transfer of hybrid nanofluids in a porous curved channel subjected to a constant wall heat flux is investigated. The interactions of various transport processes, i.e. mass, momentum and energy are considered in a fully coupled manner. Transport of nanoparticles driven by various mechanisms leading to non-uniform nanoparticle distribution is emphasized. The results showed that heat transfer increases with a higher total nanoparticle volume fraction and a larger porosity.
Increased power density in modern miniaturized electronics, caused difficulty to keep electronic perform effectively, this challenge lead to search for high-performance thermal management solutions as compact heat exchanger. Conventionally manufactured heat exchangers had limitations that thwart the development of geometrically complex heat exchangers which are capable of exploiting topological aspects to enhance the thermal performance. Subsequently, additive manufacturing (AM) is proposed as a powerful fabrication technique for compact heat exchanger based on triply periodic minimal surface (TPMS). In this work, we propose 3D compact cross flow heat exchanger (CCFHE) model with geometrically complex structures based on (TPMS) developed using STARCCM+ platform. Moreover, Computational fluid dynamics (CFD) modelling is used to obtain a new Characteristics Maps that relates Heat Transfer Effectiveness (Ɛ) and Number of Transfer Units (NTU) for the proposed heat exchanger. The convection heat transfer coefficient, pressure drop, and inlet and outlet fluid temperature are anticipated utilizing CFD method.
This work investigates a hollow version of the regular hexagonal honeycomb unit cell structure for the purpose of enhancing the in-plane stiffness. A model for calculating the relative density was developed alongside the results from numerical simulations were utilized to compare the two designs. The comparison was based on the fitted parameters of the Gibson-Ashby model. The results revealed that the hollow design offers better performance for out-of-plane direction and slightly inferior performance for in-plane directions with respect to the relative density of the unit cell.
In this paper, the effective behavior of shape memory alloy (SMA) triply periodic minimal surface (TPMS) structures is investigated by means of finite element analysis and numerical homogenization. For this purpose, the onset and subsequent thresholds of phase transformation are determined considering TPMS primitive unit cells subjected to different loading conditions. At lower void ratios, the initial phase transformation loading surfaces are found to be reasonably well represented by an anisotropic Hill's criterion. The observed fit, which also depends on geometry, degenerates as the effective martensite volume fraction increases. The determination of subsequent loading surfaces as a function of the effective volume fraction of martensite shows a nonlinear hardening behavior. Ultimately, the loading surfaces are found to reach an asymptotic state with distinctly different features compared to their initial shapes.
