Applied Mechanics and Materials Vol. 315

Abstract: In this paper the transverse vibration of a fixed-fixed end beam will be investigated by experimental measurement. This paper is concerned with the classical theory formula as well as the analysis and design of the dynamic vibration absorber (DVA) which is composed by a flexible beam with two masses symmetrically mounted at its both sides. The fixed end beam clamped to a static structure where dynamic vibration absorber then being attached onto it. One side of end of the beam is harmonically excited in transversal direction by an electric shaker. The structure equipped with accelerometer sensor to measure its vibration response amplitudes and natural frequencies. The dynamic vibration absorber arrangement located under motor near the beam end was then being vibrated and done in two conditions; before and after mounting dynamic vibration absorber. The comparison amplitudes before and after equipped dynamic vibration absorber were compared and discussed. From the experimental results, proved that the DVA has successfully absorbed the beam vibration hence reduced the vibration amplitude of the beam structure. The knowledge and result obtained from this study can help engineers control the vibration level of beam structure.

Abstract: Fuel-air mixing is important process in diesel combustion. It has been well known that wall configuration of the piston affects spray atomization. Biomass fuel, that is viable alternative fuel for fossil one, needs great help of mixing to atomization because the fuel has high viscosity and high distillation temperature. This study investigates spray atomization characteristics of rapeseed oil (RO) when it impinges on the piston wall. Optical observation of RO spray was carried out using shadowgraph photography technique. The optical images and image analysis show that wall impingement effectively promotes RO spray atomization. Spray atomization is more sensitive to wall configuration for RO than diesel fuel. The wall that has flat floor at the bottom can improve atomization. It is necessary for RO spray to promote spray penetration followed by wall-impingement because long spray path offers wide spray boundary region to form droplets.

Abstract: A number of previous studies on titanium dioxide (TiO₂) proven the presence of anatase has enhance hydroxyapatite (HAP) precipitation on TiO₂ surface which beneficial for biomedical usage especially in dental and orthopedics. The anatase phase of TiO₂ is an ideal photocatalyst agent. It helps to enhance the chemical reaction after irradiating with ultra violet (UV) light. The effect of UV light irradiation to the precipitation of HAP on TiO₂ surface while soaking in simulated body fluid (SBF) increased the formation of HAP. UV light also can be applied as pre-treatment, where UV light was irradiating before SBF immersion.

Abstract: Pakistan suffers worst energy crises due to unavailability of primary energy sources. One of the solutions to energy problems of Pakistan lies in utilization of renewable energy sources like solar energy. One of the possible uses of solar energy is in the form of water eating. This work explored the availability of solar energy in the Sindh province of Pakistan. Moreover potential fuel savings and reduction in CO₂ emission due to the use of solar water heating system is also evaluated. The RETScreen software was used for evaluation of fuel savings and CO₂ emission reduction from a solar water heating system. Results show that the annual natural gas supplied to an average household in the three main cities of Sindh i.e., Karachi, Hyderabad and Sukkur could be reduced by 513.5, 409 and 543.5 m³, respectively. Annual reductions in emissions of CO₂ for Karachi, Hyderabad and Sukkur were estimated to be 1, 0.8 and 1 tCO₂ respectively. It is concluded that the utilization of solar energy for water heating in domestic sector of Sindh Pakistan could save fuel fossil and reduce environmental pollutants that in-turn may help mitigate energy crises in the country.

Abstract: In this study, numerical simulation of tubes of various cross section under axial compression is carried out using LS-DYNA. The effect of varying configurations of tube cross-section shape on the deformation response, collapse mode and energy absorption characteristics of tubes under quasi-static axial compression have been studied. The validation of the finite element tube model was made by comparison with the experimental results of the square tube subjected to quasi-static axial compression. Tabulated results are presented and plots have been included for the specific energy absorption for different cross sections. The study provides an insight on ways to increasing energy absorption of light weight aluminium tubes.

Abstract: An educational software which can aid students in stress analysis of idealized thin-walled open sections has been developed. The software enables students to select different cross-sections which may be subjected to bending, shear or torsional loads and evaluate the stresses on it. Results obtained through this software have been validated. The software has been developed using MATLAB with graphical user interface (GUI). The software is expected to be a useful tool for effective teaching learning process of courses on thin-walled structures and aircraft structures.

Abstract: This paper reviews some basic research areas associated with Scramjet-powered hypersonic flying vehicle, particularly the forebody boundary-layer transition and intake shock-wave boundary-layer interactions (SBLI). Some technical and physical challenges in aerodynamics, aero-thermodynamics, aero-design are visited with focuses being placed on hypersonic boundary-layer transition process and its underlying physical mechanics, feasible physics-based engineering transition prediction methods, and physics-based modelling of shock-shock, shock-wave/boundary-layer interactions of Scramjet flows. Experimental, analytical and numerical studies of previously relevant studies have also been summarized with a total of twelve transition/intake configurations that can be used as benchmarks for validating physical model development and numerical simulation tools. A case study of Scramjet intake SBLI has been carried out by using computational fluid dynamics approach to understand shock induced flow separation and its consequent influences on combustion performance, along with research perspectives discussed accordingly.

Abstract: Sayong ball clay membrane can be fabricated as a cheap membrane material and available commonly at Malaysia. This work was concerned with the study of Sayong ball clay membrane as a water filtration by gel casting technique. Gel casting involves mixing process of Sayong ball clay with the solvent, monomer, dispersant, initiator and catalyst in a certain composition. Tubular membrane was fabricated by controlling the sintering temperature (1000, 1100, 1200, 1300°C). The physical measurements (shrinkage, apparent porosity, and bulk density), microstructure analysis, filtration process (flow rate) and water quality assessments (pH, color, Chemical Oxygen Demand (COD), solid suspended (SS)) were carried out at different sintering temperature. Apparent porosity and bulk density of the samples were measured by using Archimedes method. The effect of sintering temperature on microstructure of the membranes has been investigated using SEM. The experimental results showed that the shrinkage and bulk density increase with increasing sintering temperature. It gives the improvement in water quality with the lowest SS (192 mg/L), lowest COD (4 mg/L) and most colorless (1.1 Gardner units) filtered wastewater as compared to others.

Abstract: This paper presents the results of an investigation on the effect of air filter elements on the performance of Spark Ignition (SI) engine. Three different types of material; paper, cotton and foam were tested as filtering element in the air filter before the mixing process with fuel in the carburettor. In the experiment, a four-stroke single-cylinder engine was coupled to a 20kW generator dynamometer to measure engine performance parameters; engine torque, engine power (B.P), brake thermal efficiency (BTE), brake specific fuel consumption (BSFC) and brake mean effective pressure (BMEP) at various engine speeds with maximum engine load. The results show correlation between engine performance and the qualities of filtered air as a function of type of air filter element/material used.

Abstract: Flutter is a dynamic instability problem represents the interaction among aerodynamic forces and structural stiffness during flight. The study was conducted to investigate whether deflecting the control surface will affect the flutter speed and the flutter frequency. A wind tunnel test was performed using a flat plate wing made of composite material. It was found that by deflecting the control surface at 45°, the wing entered flutter state at wind speed of 28.1 m/s instead of 33.4 m/s. In addition, the flutter frequency also reduced from 224.52 Hz to 198.96 Hz. It was concluded that by deflecting the control surface, the wing experienced flutter at lower speed and frequency.