Applied Mechanics and Materials Vol. 833

Abstract: Every year, the sago processing industry in Sarawak-Mukah had generated huge amount of sago waste after the milling process and scientists have employ the waste into composite material. The fabrication and testing method are based on the Japanese A5908 Industrial Standard. Single-layer particleboards with targeted density of 600kg/m³ were produced from different sizes of sago particles. The mechanical properties of sago waste were investigated to study the feasibility of using this sample as a raw material in particleboard manufacturing. The results of the test demonstrate that samples with different sizes of particles have great influence on the mechanical properties such as Young’s Modulus, Tensile Strength and Impact Strength. The findings show that the performance of the board is affected by the different sizes of sago particles used in the experiment and had proved that sago plants can be used as an alternative raw material in the particleboard manufacturing industry.

Abstract: Pump as Turbine (PAT) always has been a favourable solution to generate electricity in rural areas when there is a potential microhydro site. Such systems have lower capital cost, and they are easier to maintain than commercially-available microhydro turbines. Normally, PAT is designed to run at a rated rotational speed so it can directly couple with an induction generator in order to match the synchronous speed. In an actual scenario, the PAT’s rotational speed changes and fluctuates with respect to flow rate due to the absence of a hydraulic control mechanism. It is essential to understand how the PAT behaves under different rotational speeds in order to design good microhydro systems. The aim of this study was to conduct simulation analysis of the effect of rotational speed on PAT’s performance curve over a range of flow rates. ANSYS CFX software was used as the Computational Fluid Dynamic (CFD) simulation tool in this study. Three distinct flow domains was modelled by Computer Aided Design (CAD) software and assembled as the computational fluid domains. Mesh independence analysis and convergence criteria were set to ensure the accuracy of the model. The torque generated by the impeller was collected from the simulation data and presented in the PAT performance curve. It was observed that the pressure head and torque generated increased at higher rotational speeds, thus maintaining the efficiency value. The results showed that the efficiency of the PAT was maintained around 76.5% for rotational speeds between 1350 to 1650 RPM, but the best efficiency point shifted to lower flow rate for lower rotational speed. The outcomes of this study will be useful for turbomachinery researchers, microhydro users, and project engineers for predicting the PAT performance for designing microhydro systems.

Abstract: Battery as the key component in stand-alone PV microgrid system tends to be the most vulnerable element in terms of durability. Poorly managed battery charge/discharge process turns out to be one of the main life-limiting factors. To improve the longevity of battery storage system, a novel energy storage system topology and its smart power management strategy is presented in this paper. This paper proposes a stand-alone 6 kW PV microgrid system with hybrid energy storage system that combines supercapacitors and batteries. Smart power allocation strategy among the SC and the battery modules is designed to dynamically allocate the power to optimally charge/discharge the batteries while fulfilling the variations in supply and load. The performance of the proposed system is evaluated via model simulation using Matlab/Simulink. The system is simulated under a typical 24-hours residential load profile and the results proved that the proposed system can provide sufficient power to regulate the fluctuations in supply and load. During the process, the batteries are charged / discharged with ideal charge rate and operated under a low depth-of-discharge that have proven to prolong the battery lifetime.

Abstract: Awareness on implementing sustainable construction materials has risen significantly leading to increased renewable materials used commercially. Kenaf fibers are potentially used as composite reinforcements and combined with epoxy polymer to produce an advanced engineering material that may offer superior specific stiffness (and strength) to its density. Other advantages include renewability, easy during fabrication handling stage and relatively cheaper than commercial fibers counterparts. Current project aims to investigate mechanical strength of woven fabric kenaf composites coupons with different stacking orientations. Testing series under investigation includes different lay-up types with variation of plate thickness. Mechanical testing is conducted referred to relevant code of practice and associated damage observations during testing will be recorded. It is suggested that these materials are potential to provide an alternative reinforcing materials in composite fabrications and enhanced its applicability to a greater extent in local sector.

Abstract: Wind energy known as a cheap, clean and uncontrolled resource and becomes an important green electricity source. However, installation of wind system into an electric grid introduces the Power Quality (PQ) phenomenon. These poses great challenges leads to various control schemes and new techniques to mitigate the PQ events. This paper described the improvement of PQ events in a grid connected wind energy system by using Static Compensator (STATCOM) with a Battery Energy Storage System (BESS) at the Point of Common Coupling (PCC). The performance of the proposed wind energy system is simulated via MATLAB/SIMULINK in power system block set.

Abstract: Bioethanol fuel produced from biomass and bioenergy crops has been proclaimed as one of the feasible alternative to gasoline in internal combustion engines. In this study, the effect of gasoline–ethanol–methanol (GEM) ternary blend on performance characteristics of petrol engine was studied. Three different fuel blends, namely, E0 (gasoline), G75E21M4 (75% gasoline, 21% hydrous ethanol and 4% methanol) and E25 (25% anhydrous ethanol and 75% gasoline) were tested in a 1.3-l K3-VE spark-ignition engine having four cylinders, dynamic variable valve timing, and electronic fuel injection. The experimental results revealed that using G75E21M4 fuel blend increased the air-fuel ratio, engine power, torque, brake thermal efficiency, and mean effective pressure compared to E0 and E25, however, fuel consumption also increased.

Abstract: Complicated Lamb wave propagation in structures can cause a misinterpretation in defect location and sizing during nondestructive inspections. A visualization of Lamb wave interactions with oval defects was carried out in our study to investigate the phenomenon of fundamental Lamb wave interaction around defect by using a reduced model of plate in ABAQUS. The visualized wave propagations with oval shape of through defects in plates demonstrated different patterns of wave interactions for the symmetric and anti-symmetric modes. The results also visualized the mode conversions around defects which converted from the incident waves. The visualized changes on the wave structures due to wave interaction with defects is important to increase our understanding on the guided wave propagation and reduce misinterpretation in nondestructive inspection when using the wave modes during inspection on large structures.

Abstract: Matching layers of acoustic impedance are intensively studied in ultrasonic transducers for the efficiency of wave transmission. Large impedance mismatch between the active element of piezo and parent material in long range ultrasonic is also expected to have the similar affects on the ratio of the transmitted and reflected waves which can cause high reflection at the interface that result acoustic wave ringing and indicate low transmitted energy for inspection over large areas. This simulation study present analysis of Lamb wave propagation through a single matching layer from a piezoelectric transducers. It explains transmitted waves into aluminum plate using different materials of matching plates at thickness of quarter wavelength. Four matching plates with close to the computed value of acoustic impedance had been used in FEM simulations to study effect of the matching layers on the transmitted Lamb wave in aluminum plate. The results indicated slightly different phenomenon of multiple wave reflections from the transmitted S0 and A0 modes at boundary of the matching layer.

Abstract: Homogeneous base catalyst has wide acceptability in biodiesel production because of their fast reaction rates. However, postproduction costs incurred from aqueous quenching, wastewater and loss of catalysts led to the search for alternatives. Heterogeneous base catalyst is developed to cater these problems. The advantages of heterogeneous catalyst are their high basicity and non-toxicity. This work compared the production of biodiesel using two different kind of catalysts that is homogeneous catalyst (sodium hydroxide, NaOH and potassium hydroxide, KOH) and heterogeneous catalysts (calcium, oxide, CaO catalyst derived from chicken and ostrich eggshells). Transesterification of waste cooking oil (WCO) and methanol in the presence of heterogeneous base catalyst was conducted at an optimal reaction condition (calcination temperature for catalyst: 1000 °C; catalyst loading amount: 1.5 wt%; methanol/oil molar ratio: 10:1; reaction temperature: 65 °C; reaction time: 2 hours) with 97% biodiesel yield was obtained. While, the homogeneous base catalyst gave higher biodiesel yield of 98% at optimum operating condition (catalyst concentration: 0.75 wt%; methanol/oil molar ratio: 6:1; reaction temperature: 65 °C; reaction time: 1 hours). The slight difference in the biodiesel yield was due to the stronger basic strength in the homogeneous catalyst and were not statistically not different (p=0.05). However, despite these advances, the ultimate aim of producing biodiesel at affordable low cost and minimal-environmental-impact is yet to be realized.