Improving mechanical properties of aluminium alloy through addition of coconut shell-ash

This paper investigates the microstructure and mechanical properties of aluminum alloy (Al-Si-Fe) reinforced with coconut shell-ash particulate. The aluminium (Al-Si-Fe) alloy composite was produced by a double-stir casting process at a speed of 700 rpm for 10 and 5 minutes at first and second stirring respectively. The samples produced from addition of 0-15 wt% coconut shellash particles (CSAp) were prepared and subjected to microstructural and mechanical properties testing. The results of the microstructural analysis of the composite reveal a fairly uniform distribution of the coconut shell-ash particles in the matrix with increase in volume fraction of CSAp. The mechanical property test results revealed that, hardness of the developed composite increased with increasing percentage weight of CSAp. Also the tensile and yield strength at 0.2% offset values of Al-Si-Fe/CSAp composite increased with percentage increase in CSAp up to 9% addition above which a little decrease in both tensile and yield strength was observed.Keywords: Matrix, coconut shell, mechanical properties, stir- casting, particulate, reinforcement

Mechanical Description of a Hyper-Redundant Robot Joint Mechanism Used for a Design of a Biomimetic Robotic Fish

A biologically inspired robot in the form of fish (mackerel) model using rubber (as the biomimetic material) for its hyper-redundant joint is presented in this paper. Computerized simulation of the most critical part of the model (the peduncle) shows that the rubber joints will be able to take up the stress that will be created. Furthermore, the frequency-induced softening of the rubber used was found to be critical if the joints are going to oscillate at frequency above 25 Hz. The robotic fish was able to attain a speed of 0.985 m/s while the tail beats at a maximum of 1.7 Hz when tested inside water. Furthermore, a minimum turning radius of 0.8 m (approximately 2 times the fish body length) was achieved

Performance Improvement of an Indirect Solar Dryer with Single Axis Manual Tracking System and Angular Simulation of the Flat Plate Collector Reflectors

The need of food preservation cannot be over-emphasised. Crops need to be processed and preserved in times of their abundance to ensure for life and specie sustainability in times of scarcity. Flat plate collectors (FPCs) are often made fixed and the positions of reflectors used on them are not normally specified; in this paper, a report of an experimental test of an indirect solar dryer whose FPC is operated manually in a single axis to track the sun is presented. To avoid incurring extra cost on the existing design, the FPC was rather made to be operated manually instead of the automation process. Using the Engineering Equation Solver (EES) and the TRNSYS 16 softwares, the angular positions of reflectors placed east and west on the FPC were simulated for the first quarter months of the year of the experiment – this included the month of the test. This is to ascertain the best positions for the reflectors in other to achieve maximum insolation. For the month of the test, March, the angular positions of the reflectors placed east and west of the FPC were found to be 40° and 80° respectively relative to the horizontal plane. The performance of the solar dryer in terms of the percentage moisture loss, drying rate, collector efficiency and drying efficiency was evaluated when the FPC was fixed and when it was made to track the sun and the results obtained there from were compared. In comparison, it was found that the dryer tested by manually tracking the sun increased the total percentage moisture loss by 5.11%; the total drying rate by 2.10×10-5 kg/s; the average collector efficiency by 3.92% and the overall drying efficiency by 2.0% as compare to when the FPC was fixed, i.e. not tracking the sun. The indirect solar dryer with the ability to manually track the sun in a single axis using the meteorological conditions of Zaria, Nigeria was therefore found to have increased the performance of the system dryer as compare to when tracking of the sun was not done

Sodium Benzoate and Bitumen Coatings as Inhibitors of Corrosion Deterioration of Mechanical Properties of Low Carbon Steel

ABSTRAC

Development and Performance Evaluation of a Three Rollers Acha (Digitaria exilis) Dehusking Machine

In this study, a three rollers Acha-dehusking machine was designed, constructed and tested. The machine has the following units - feeding, processing and separating unit. The materials used for the fabrication were selected locally based on the design considerations and design analysis of the machine components. The three rollers Acha-dehusking machine which cost ₦52 300 at the time of its fabrication was finally assembled and evaluated. The Acha paddy fed through the hopper was made to pass through two roll gaps between fixed and adjustable rollers rotating in opposite direction at a speed ratio of 1.5:1 where it was abraded and dehusked. The mixture of the dehusked grain and the husk were separated by current of air blown from the winnowing fan in the separating unit. The dehusked grains, husk and the undehusked grains were separated and weighed. From the outcome of the test, the efficiency and the output of the machine were found to be 69.6% and 22.14Kg/hr respectively

Modal Analysis of 27 mm Piezo Electric Plate for Small-Scale Underwater Sonar-Based Navigation

This work presents progress towards the development of a small-scale, purely sonar-based navigation device for a robotic fish (~394 mm long). Aperture overloading of small (5 mm diameter) ultrasonic transmitters does not allow them to be used effectively inside water. A test on a 27 mm diameter buzzer piezo plate shows promising performance under water at frequencies from 4.5 kHz to 80 kHz. ANSYS-based simulation was therefore used to find modal frequencies at higher frequencies so as to optimize this encouraging result. The simulation process also discovered several antiresonant frequencies such as 38.5 kHz, 54 kHz, and 57.5 kHz. All frequencies above the 8th harmonic (10,589.02 Hz) are out of phase with the input load except a resonance frequency of 42.5 kHz and an antiresonance frequency of 56.5 kHz. Also, the first harmonic (1,648.73 Hz) is the only frequency that gave a nodal deformation