In this work, the effects of adding activated carbon (AC) powder with epoxy resin were investigated experimentally. The particulate epoxy composites are manufactured in vacuum technique with different weight fraction ratios of AC (0, 5, 10, 15, 20, 25, 30, 35 and 40) % wt. The particle size was measured during this work by laser particle size analyzer with an average size of about (14.74μm). The interaction between epoxy material and AC powder was examined by using Fourier Transform Infrared (FTIR) spectroscopy analysis. Moreover, the glass transition temperature (Tg) of the pure epoxy and composite material were measured by Differential Scanning Calorimeter (DSC). The tensile strength behavior and interaction strength between the matrix material and powder were investigated by conducting tensile test and SEM analysis. The results of FTIR test reveal that there is no a new peak after reinforcing epoxy with AC powder, which proves there is a strong interaction between epoxy resin and AC powder. The DSC results show that the increases by adding AC to epoxy will increase Tg temperature. The findings of FTIR analysis were supported by SEM analysis, which shows a good interaction and strong interfacial between matrix and particles. The tensile strength values increased with increasing AC content up to 15 % wt. with a max value of 26.34 MPa (19.16%), then it decreased to 18.15 MPa at 40 % wt.
Rotating machines have many applications, in several mechanical systems. They typically contain a rotary shaft as an influence conversion unit, that is subject to multiple loads in operation. One of the most widely-used rotary machines is the pump, and pump shafts are exposed to many forces due to fluids, unbalancing due to slight bending in the shaft or errors of design or bearings, bearings-induced forces, etc. These forces can reach an unacceptable level once the rotor is functioning close to its natural frequencies. Excessive vibration levels within the device cause fatigue and thus tiny cracks may grow to a serious extent and ultimately cause failure. In this study, dynamic analysis of the pump shaft was made, with and without cracking. Fundamental bending natural frequencies and torsional natural frequencies, response shaft, the equivalent stresses and total deformations in each dynamic and static cases were evaluated. The dynamic load factor (DLF) was calculated in the presence of cracks of various depths (4mm, 6mm, 8mm, 10mm, 12mm) set at diverse locations (x=80mm, x=166mm, x=210mm) measured from the point of overhanging. The finite element method by ANSYS package was used to conduct the numerical analysis for this study, and a specific experimental test rig was built to verify the experimental results. Results showed that increasing depth of the cracks will lead to reducing in the natural frequency and, as a result, increase instability in the shaft. When the location of the crack is close to the highest bend point in the shaft, the natural frequencies will increase. In addition, the equivalent stress depends on cracking location and it is increased with increased depth of cracking.
Reciprocating internal combustion engines are common and thus important engines due to the many advantages they provide. Despite significant improvements being made to these types of engines in recent decades, however, they still suffer from low efficiency due to large losses in produced energy, which occur for multiple reasons. The crank mechanism is responsible for much of the observed energy loss, however. In the current study, a new mechanism is suggested to transmit kinetic energy directly from the pistons, thus reducing energy losses associated with the crankshaft. This new mechanism eliminates the crankshaft from power transmission, limiting it to syncing piston movement. The pistons are then modified to mate with partial teething gears, which then transmit the kinetic energy directly from the pistons without this energy being negatively affected as it is by the angular position of the crank units. The testing results show that the power produced during the power stroke in the suggested engine is twice corresponding output of a classical engine.
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