Wahyu Kuntjoro

Tensile strength of notched woven fabric hybrid glass, carbon/epoxy composite laminates:

This study investigates the effect of hybridization on tensile strength of woven fabric glass/epoxy composite laminates with two different notch sizes of 5 mm and 10 mm. Tensile tests are performed on notched [0°/90°]3s specimens of woven fabric C-glass/epoxy composite laminates and their hybrid reinforced with woven fabric 3K-carbon layers in order to measure tensile strength and characterize damage mechanisms. The results suggest that hybridization has a considerable effect on the improvement of the tensile strength of C-glass/epoxy composite laminates but also has reduced the rupture strain of the composites. Microscopic observation of specimens after tensile loading reveals the existence of transverse and longitudinal cracks, delamination and transverse fiber damage in hybrid composite laminates.

Effect of matrix modification on the mechanical properties of short carbon fiber-reinforced epoxy composites:

Effects of matrix modification using liquid epoxidized natural rubber (LENR) on the mechanical behavior of short CFreinforced epoxy composite were investigated in this study. Composite samples were prepared in four different concentrations: 3, 5, 7, and 10 wt% fiber fractions. Flexural and fracture toughness tests were performed to observe the mechanical behavior of the samples. LENR improved the mechanical properties due to the plasticizing effect of rubber particles which increased the flexibility and led to a higher debonding strength. The results showed that the treated carbon had improved the flexural strength and flexural modulus by 77% and 21.8% at 7 wt% fiber loadings, respectively, while fracture toughness increased by 15% at 10 wt% fiber loadings compared to the neat epoxy.

Effect of Carbon Fibre Ratio to the Impact Properties of Hybrid Kenaf/Carbon Fibre Reinforced Epoxy Composites

Effects of the incorporation of untreated and treated hybrid kenaf/carbon fibre reinforced epoxy composites on the impact properties were studied. Hybrid kenaf/carbon fibres and thermoset matrices were hand-laid up and characterized in terms of its mechanical properties. The kenaf fibres were alkali treated whilst the carbon fibres were gamma radiation treated before use as reinforcement in the epoxy resin matrix. The reinforcing effects of kenaf hybridized with carbon fibre in epoxy composites were evaluated at various fibre loadings with overall fibre contents 20 wt%. Hybrid composites with different ratios of kenaf fibre : carbon fibre ; 0.9:0.1, 0.8:0.2, 0.7:0.3 and 0.6:0.4 were prepared. Impact tests of untreated and treated hybrid kenaf/carbon fibres were performed. The fractured surfaces of these composites were investigated by using scanning electron microscopic technique (SEM) to determine the interfacial bonding between the matrix and the fibre reinforcement. It was found that the treated hybrid composites increased the impact strength by 26% compared to the untreated ones.

Investigation on aerodynamic characteristics of baseline-II E-2 blended wing-body aircraft with canard via computational simulation

Previous wind tunnel test has proven the improved aerodynamic charasteristics of Baseline-II E-2 Blended Wing-Body (BWB) aircraft studied in Universiti Teknologi Mara. The E-2 is a version of Baseline-II BWB with modified outer wing and larger canard, solely-designed to gain favourable longitudinal static stability during flight. This paper highlights some results from current investigation on the said aircraft via computational fluid dynamics simulation as a mean to validate the wind tunnel test results. The simulation is conducted based on standard one–equation turbulence, Spalart-Allmaras model with polyhedral mesh. The ambience of the flight simulation is made based on similar ambience of wind tunnel test. The simulation shows lift, drag and moment results to be near the values found in wind tunnel test but only within angles of attack where the lift change is linear. Beyond the linear region, clear differences between computational simulation and wind tunnel test results are observed. It is recommend...

Static stability of Baseline-II blended wing- body aircraft at low subsonic speed: Investigation via computational fluid dynamics simulation

A study of the effect of canard to Baseline-II blended wing-body aircraft is presented here with emphasis on investigating contributions of canards various setting angle to aerodynamic parameters and longitudinal static stability. A computational fluid dynamic (CFD) simulation has been conducted at low subsonic speed to collect aerodynamic data and found that its aerodynamic trend is similar to many BWB aircraft and consistent to previous studies conducted in UiTM. Canard setting angle affects the value of lift-at-zero incidence of a BWB aircraft, although fairly small for current canard size that it is not adequate to produce positive pitching moment-at-zero lift. Baseline-II is partially, statically stable in longitudinal motion because of negative moment change w.r.t. lift change but it has equilibrium incidence angle that only produces negative lift. Larger canard and/or modification to Baseline-II wing-body are needed to overcome this flaw. The location of new reference point provides ‘comfortable’ static margin. Data and mathematical characteristic obtained from BL-IIA SP CFD simulation is comparable to those from wind tunnel experiment and both show satisfactory-to-good correlation to theoretical calculations.

Ballistic limit of aluminium tank: An experimental study

This paper presents the details of experimental set-up to determine the ballistic limit for the aluminium tank for two cases, empty and water-filled tank. The experiment was carried out at Science and Technology Research Institute for Defense (STRIDE) Batu Arang. The aluminum tank was 3 mm thick, 150 mm wide and 750 mm long. At the end of the tank were closed with two Polymethyl methacrylate (PMMA) windows. Silicone was used to seal the contact between the end of the tank and PMMA. Four steel bars used to fix the windows to the tank. Fragment simulating projectile (FSP) was used to the impact the aluminium tank. The velocity varied from 239 m/s to 972 m/s. Among results obtained were ballistic limit for the front and rear of the tank, correlation between impact velocity versus residual velocity, damage area, wall deflection, velocity drop and terminal ballistic for empty and water-filled tank.

An Experimental Study on the Ballistic Impact Behavior of Non-Filled Tank against Fragment Simulating Projectile (FSP)

This paper presents the ballistic impact study for the non-filled aluminum tank. The objective was to determine the ballistic limit for front tank wall and rear tank wall. The tank was impacted with fragment simulating projectile (FSP) with various velocities range from 239 m/s up to 556 m/s. The aluminum tank was 3 mm thick, 150 mm wide and 750 mm long. The ends of tank were closed with two Polymethyl methacrylate (PMMA) windows which fixed to the tank with four steel bars. The test was conducted at the Science and Technology Research Institute for Defense (STRIDE) Batu Arang, Selangor. The results showed that the ballistic limit for the front tank wall and rear tank wall was 257.7 m/s and 481 m/s, respectively.

Advanced Autonomous Multirotor Response System

Autonomous Unmanned Aerial Vehicle (UAV) in the form of multi-rotor system is having a great potential in various applications such as disaster management (as first response system) and surveillance. It is known that conventional helicopter system, capable of hovering, is practical and reliable as many applications have confirmed its capabilities. However it is only achievable once highly optimized control architecture is realized. The objective of the research presented in this paper is, to develop a small multi rotor UAV system that is able to autonomously flying from one way point to another in a stable manner. This small UAV is termed as Mini (or Micro) Aerial Vehicle (MAV). In this project, a four-rotor system was developed, and becoming the platform of various sensors system, flight control system, and electric propulsion system. The MAV was programmed to be able to lift off and fly to waypoints making use of GPS. This paper presents the architecture of the MAV and its autonomous flight.

A study about the split drag flaps deflections to directional motion of UiTM's blended wing body aircraft based on computational fluid dynamics simulation

This paper discusses on the split drag flaps to the yawing motion of BWB aircraft. This study used split drag flaps instead of vertical tail and rudder with the intention to generate yawing moment. These features are installed near the tips of the wing. Yawing moment is generated by the combination of side and drag forces which are produced upon the split drag flaps deflection. This study is carried out using Computational Fluid Dynamics (CFD) approach and applied to low subsonic speed (0.1 Mach number) with various sideslip angles (β) and total flaps deflections (δT). For this research, the split drag flaps deflections are varied up to ±30°. Data in terms of dimensionless coefficient such as drag coefficient (CD), side coefficient (CS) and yawing moment coefficient (Cn) were used to observe the effect of the split drag flaps. From the simulation results, these split drag flaps are proven to be effective from ±15° deflections or 30° total deflections.

A study on propeller performance of a fuel cell powered propulsion system

The internal combustion engines that are widely used as power sources nowadays emits hazardous emissions that can cause negative consequences on the environment and society such as pollution and climate change. Transportation industries are starting to rely on the renewable energy as the alternative energy sources for the future. Fuel cells are a promising alternative power source for vehicles because of their high specific energy, efficiency, and reliability. Hydrogen proton exchange membrane (PEM) fuel cells produce zero carbon emissions. The electrochemical processes that generate power exhaust only water vapor and heat. Fuel cell research for aircraft is relatively new. Therefore, there is a need for a thorough study on the development of the fuel cell powered aircraft. A five meter wingspan unmanned aerial vehicle technology demonstrator, called Kenyalang-l, was recently developed at Universiti Teknologi MARA. A Horizon H-1000 PEM fuel with a maximum power of 1 kW was used as the primary power plant for its DC brushless motor propulsion system. The system was tested in ground-based static tests. The objective of the research that is reported in this paper is to obtain the performance characteristic of the fuel cell propulsion system. The data collected from these tests includes the output voltage, output current, power, thrust, and rotational speed of the system. Results and analysis of this data were used to characterize the effectiveness of the fuel cell propulsion system. The results obtained indicate that the thrust of the propeller is directly proportional to output power generated by the fuel cell.