Applied Mechanics and Materials Vol. 315

Abstract: Concern regarding the shielding effectiveness (SE) of building materials is gaining more response nowadays due to the awareness on the electromagnetic pollution (EMP) that is believed to results in disastrous consequence. A pure concrete inherently providing certain level of SE but it is not enough. Hence additional shielding and absorbing additives are added into the concrete. In this work Mn_xZn_1-xFe₂O₄ will be added into the pure concrete to enhance its SE performance. The effect of microstructure, compositions, grain sizes, homogeneity, mixture volume of the Mn_xZn_1-xFe₂O₄ will be considered for the optimization in this mixture. The key component to determine the SE of concrete is their electrical characteristic (relative permittivity and relative permeability). The parallel plate which is proposed previously will be used to determine the electrical characteristic of material and it will also be used for SE measurement.

Abstract: The contribution and presented work deals with the CFD simulation of heating and air conditioning process of a special vehicle. The aim of the work is then the capacity validation of the heat exchanger which provides the heating or cooling of the air supplying the vehicle. Because of the high dimensionality and complexity of the whole task, the number of simplifications in the form of proper boundary conditions and constraint equations was proposed by authors. The presented paper contains the presentation and discussion of the used simplifications, the saved computational capacities are accented and results in the form of distribution of thermomechanical quantities are presented. Finally, the capacity of heat exchanger used is validated.

Abstract: In this study, the effect of load on the tribological performance of RBD palm olein is investigated using a four-ball wear tester according to the standard test of ASTM D4172. Tests were conducted with 40, 60, 80, 100 and 120 kg normal loads. The experimental temperature and rotational speed were held constant at 75 °C and 1200 rpm, respectively. The test duration was 60 minutes in all cases. For each load, the tribological properties of RBD palm olein were compared with the properties of additive-free paraffinic mineral oil. The results focused on the frictional torque, wear scar diameter, friction coefficient and the flash temperature. Following the completion of the wear test experiments, the ball wear condition and lubricant properties were observed. These results show that RBD palm olein has a lower coefficient of friction than paraffinic mineral oil; however showed a high oxidation effect under high temperature work conditions.

Abstract: This study investigates the physical properties of pure palm fatty acid distillate (PFAD) as a new, clean and renewable source of lubricant and hydraulic oil. This study is done using a four-ball tribotester. The experiments are conducted at five different temperatures of 55, 75, 95, 105 and 125 °C. The rotational speed was fixed at 1200 rpm, normal load was 40 kg and duration was 1 hour. For evaluating the results, all experiments again were conducted using commercial engine mineral and hydraulic mineral oil and at the end all results were compared together. The results show that PFAD has higher anti friction and anti-wear ability.

Abstract: The wide use of conventional lubricants causes pollution to the environment and the rising awareness on green house effect has triggered the use of environmental friendly and biodegradable lubricants in the industries. Palm olein was selected to be a candidate due to its superior tribological properties and large production in country. In the research, the behavior of palm olein characteristic was investigated by using pin-on-disk experiment in which the pin was loaded against the rotating grooved disk. The experiments by sliding were performed via pin on disk tester using stainless steel as the material for both flat ended pin and grooved disk. The test were carried out by dropping 5 ml of palm olein as lubricant on the sliding surface at two different speeds which were 0.25 and 1 m/s. In this study, the wear rate of the pin and friction coefficient was investigated. The weight loss and surface roughness before and after experiment were analyzed. All the results obtained were compared to hydraulic oil and paraffinic mineral oil. From the analysis, friction coefficient acquired with lubrication of palm olein was the lowest for both conditions, while the wear rate obtained also showed a similar trend. The pin lubricated with palm show the lowest result of wear rate and weight loss.

Abstract: In this paper, the effect of sliding speed on the anti-friction of RBD palm olein was investigated using four-ball tribotester. The speeds were varied from 800 to 1400 rpm. The normal load was set to 40 kg and the test oil was heated up to 75 °C before the experiments. The result showed that palm olein has low friction coefficient compared to additive-free paraffinic mineral oil.

Abstract: Biodiesel is one of the alternative fuels used in oil burner. In order to determine the quality of this biodiesel produced at UTHM Biodiesel Pilot Plant, it is tested in crucible furnace system. This study is focused on the effects of biodiesel on emissions from an oil burner. It uses 5 % (B5), 10 % (B10) and 15 % (B15) biodiesel blended with diesel. 100 % diesel is used as a comparison. Emissions from the combustion of diesel burner were measured using gas analyzer and smoke detector. Measured parameters were carbon monoxide (CO), hydrocarbon (HC), carbon dioxide (CO₂) and opacity. Results show a significant improvement up to 87 % of harmful emissions showed by blended fuel compared to 100 % diesel. The overall results indicate the potential of palm oil biodiesel blend in reducing harmful emissions from the burner system.

Abstract: Shape Memory Alloy (SMA) has been identified as an ideal candidate to actuate the finger joints of hand prosthesis due to its silent operation, small size, high force to weight ratio and operational similarity with human muscles. When current is applied to a SMA wire, the material is heated up. A phase transformation from Martensite to Austenite takes place and the wire contracts. This work evaluates the displacement and force produced from the contraction of a type of SMA wire, i.e. Nitinol (Ni-Ti). The displacement is determined by a linear potentiometer while the force is determined by a load cell. Furthermore the impacts of varying the bias force exerted on the SMA wire and the input current passed through the wire are investigated. Such insight into the characteristics of SMA can be used to realize biomimetic actuation in order to improve the dexterity of hand prosthesis.

Abstract: Active damping using piezoelectric element is one of the effective techniques to counter vibration problems. A 3D finite-element model is developed as part of investigation for damping control. The piezoelectric patches are surface bonded on quadrilateral thin plate and supported with spring damper elements. The main goal of this paper is to investigate mechanical characteristics of piezoceramic array on membrane and the effect of force excitation using small motor and electric excitation on the system. The system setup produced small vibration displacement and does not displace the plate beyond elastic strain region. The results show the linear behavior of piezoceramic and the correlation between electric excitation, motor vibration and displacement at the centre of the plate at different frequency range. The mode shapes and natural frequencies at low frequency spectrum are also presented. Therefore, the results can be used as reference to develop damping system with aid of piezoelectric patches.

Abstract: Solid oxide fuel cell (SOFC) is currently popular due to its capability to convert hydrogen into electricity directly from oxidizing hydrogen fuel. The SOFC is one of the expected renewable energy devices and green technology in the future because of less carbon dioxide production and no pollutant product. Performance of SOFC was influenced by morphology and microstructure of the material, starting particle size and particles distribution. This paper addresses the comparative evaluation of using pretreatment NiO/YSZ powder using ball mill and ultrasound processess on the performance of a single cell SOFC. The performance of solid oxide fuel cell was evaluated using scanning electron microscopy (SEM), X-Ray diffraction (XRD) and impedance spectroscopy, measured at room temperature. The results indicate that the treatment using ultrasound process is better than ball mill process due the total resistance is smaller and distribution particle is more homogenous.