Showing papers in "Mechanical engineering series in 2022"

Mechanical Behavior of Materials

Abstract: This textbook supports a range of core courses in undergraduate materials and mechanical engineering curricula given at leading universities globally.

A Framework on Electrochemical Machining of ABS-15% Al Composite

Abstract: In commercial practice, electrochemical machining (ECM) is being widely used for material removal of electrically conducting workpiece. But hitherto little has been reported on ECM of thermoplastic composites due to limited electrical conductivity. In the present work, injection moulded acrylonitrile butadiene styrene (ABS) matrix with reinforcement of 15% Al (by weight) sample has been selected for machining by ECM as a case study. The ABS-15% Al composite has been selected based upon previous studies reported for joining of dissimilar thermoplastics on the basis of rheological property. This chapter represents machining capability of ABS-15% Al with ECM. The upshot of this study shows that the machining of thermoplastic material reinforced with Al powder can be performed with the help of ECM. The results were analysed with the help of scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) data.

Heat Transfer Results in Micro-fin Tubes

Abstract: Using the experimental setup detailed in Chap. 2, this chapter presents heat transfer results in the entrance and fully developed regions of the micro-fin tubes, the effect of inlet configuration (square-edged and re-entrant) and buoyancy on the entrance and fully developed heat transfer in all flow regimes (laminar, transitional, and turbulent), the effect of inlet configuration on the start and end of transition of the fully developed heat transfer, and the effect of fin geometries (spiral angle, fin height-to-diameter ratio, and number of starts) on heat transfer.KeywordsSingle-phase flowMicro-fin tubesHeat transferEntrance regionFully developed regionUniform wall heat flux boundary conditionLaminar flowTransitional flowTurbulent flowSquare-edged inletRe-entrant inletStart and end of transition of the fully developed heat transferFin geometries (spiral angle, fin height-to-diameter ratio, and number of starts)

Hydrocarbon Emissions from Spark-Ignition Engines

Abstract: To contrast the phenomenon of HC formation in a diesel and a spark-ignition engine, a chapter is included on the latter. The absorption and desorption of fuel by cylinder lubricating oil films have been modelled using principles of mass transfer in this chapter. Henry’s law for a dilute solution of fuel in oil is used to relate gas to liquid-phase fuel concentrations. Mass transfer conductances in gas and liquid phases are considered, the former via the use of Reynolds’s analogy to engine heat transfer data, the latter through assuming molecular diffusion through an effective penetration depth of the oil film. Oxidation of desorbed fuel is assumed complete if the mean of burned gas and lubricating oil film temperatures is greater than 100 K. Below this value, the desorbed fuel is considered to contribute to hydrocarbon emissions. Comparison with engine test data corroborates the absorption/desorption hypothesis. The model indicates the equal importance of gas and liquid-phase conductance.

Experiments

Abstract: During the past 50 years Transmission Electron Microscopy (TEM) has evolved from an imaging tool to a quantitative method that approaches the ultimate goal of understanding the atomic structure of materials atom by atom in three dimensions both experimentally and theoretically. Today’s TEM abilities are tested in the special case of a Ga terminated 30 degree partial dislocation in GaAs:Be where it is shown that a combination of high-resolution phase contrast imaging, Scanning TEM, and local Electron Energy Loss Spectroscopy allows for a complete analysis of dislocation cores and associated stacking faults. We find that it is already possible to locate atom column positions with picometer precision in directly interpretable images of the projected crystal structure and that chemically different elements can already be identified together with their local electronic structure. In terms of theory, the experimental results can be quantitatively compared with ab initio electronic structure total energy calculations. By combining elasticity theory methods with atomic theory an equivalent crystal volume can be addressed. Therefore, it is already feasible to merge experiments and theory on a picometer length scale. While current experiments require the utilization of different, specialized instruments it is foreseeable that the rapid improvement of electron optical elements will soon generate a next generation of microscopes with the ability to image and analyze single atoms in one instrument with deep sub Ångstrom spatial resolution and an energy resolution better than 100 meV.