Applied Mechanics and Materials Vol. 315

Abstract: This project is about an experimental impact resistance and behaviour of sandwich panel structure, consists of steel plates and kenaf foam. The use of natural fiber reinforcement foam could give a great advantages in weigh reduction which very useful in military mobility and transportability. A standard rifle was used to launch a small bullet (5.56 mm) in constant velocity towards the sandwich panels. The experiments result is based on the depth of the indentation due to the penetration against the armour. The best specimen combining both parameters of study is 20% of kenaf with 45 mm thickness because it can resists the most impact from the bullet. Therefore, it can be concluded that using kenaf to reinforce the polyurethane is success in enhancing its strength and mechanical properties.

Abstract: Distribution pattern of spray boom in fields is affected by several parameters which one of the important reasons is horizontal and vertical vibrations because of unevenness surfaces. Spray boom movements lead to decrease of spread efficiency and crop yield. Generally, active suspension is employed to control and attenuate the vibration of sprayer booms because these suspensions reduce the high frequency vibration of spray booms thanks to irregularities soil. In this research, a proportional-integral-derivative controller with active force control is used to remove undesired rolling of spray boom. Simulation results depict that the proposed scheme is more effective and accurate than PID control only scheme. The AFC based scheme shows the robustness and accuracy compared to the PID controller.

Abstract: The objective of this study is to determine the vibration value of Palm Oil Harvester Machine or CANTAS motorized cutter profile. The CANTAS machines have been divided into twelve nodes and hand arm vibration measurements are taken for idle and full throttle operation. Three cutting heads provided by MPOB have been measured for comparison purposes. The hand-arm vibration values for Type A Cutting head achieves (3.89±1.10) m/s² for idle condition and (10.71±2.88) m/s² for full throttle condition. Meanwhile Type B Cutting Head achieves (3.63±0.87) m/s² for idle condition and (11.22±1.74) m/s² for full throttle condition. Type C of Cutting Head yields (3.51±0.82) m/s² for idle condition and (15.54±3.81) m/s² for full throttle condition along the structure. The results also shows which points depicted highest vibration level during idle (no operation, ideally from tree to tree) and full throttle (overuse operation). These values present the maximum and minimum vibration levels that will be received by the user in daily usage of the machine. design in reducing vibration to the hand-arm of the user.

Abstract: This paper presents the simulation of modeling a flexible link system that will be used as a new method to generate dissolved oxygen. This method is inverted as compared to other researches done in this field. The vibration generated from the movement of the flexible link will generate waves and bubbles in water thus generating dissolved oxygen. The results of the simulation are presented.

Abstract: A natural fibre-based composite from woven kenaf was fabricated using hydraulic hot press machine. Plain woven kenaf fabrics were prepared and used as reinforced material with ABS sheet followed by hot press. Woven fabric was treated using sodium hydroxide and being compare with untreated fabric. The effect of the processing temperature and time towards tensile properties of the composite were investigated. Tensile test was carried out to measure the strength of the composite towards the effect of processing temperature and time. The surface morphology of the composite was studied with Scanning Electron Microscope (SEM) and Optical Microscopic. The result shows that woven Kenaf degrade in strength when expose with high temperature and long exposure to the heat. The permeability of woven Kenaf plain fabric does not indicate a good penetration as observed by microscopy.

Abstract: The accuracy and reliability of the new stress tensor decomposition to capture the plasticity behaviour of orthotropic materials under plane-stress conditions was examined in this paper. No experiment was required to perform this work. Therefore, the suitable, published paper which provides a relevant test result and sufficient material properties to characterise the new stress tensor decomposition, was used. This new stress tensor decomposition was used to presents a new yield criterion for orthotropic sheet metals under plane-stress conditions in this work. This was done by assuming the yield surface to be circular in the new deviatoric plane. The predictions of the new effectice stress expression were then compared with the experimental data of 6000 series aluminium alloy sheet (A6XXX-T4) and Al-killed cold-rolled steel sheet SPCE. The predicted new yield surfaces are in good agreement with respect to the experimental data for two materials (A6XXX-T4 and SPCE).

Abstract: This paper presents the differences of anthropometric data between Malaysian, Chinese, Korean, Japanese, Taiwanese, North American, North African, South Indian, Portuguese and Australian, which can be use in anthropometric test dummy (ATD) and the computational modelling of ATD. The available anthropometric data of stature, sitting height and sitting knee height for male and female are analyzed by weighting them according to their ranking in the corresponding parameters and presented in bar chart. It is found that Australian male and female have the biggest body posture compared with others. The results also indicate that females in Australia, North Africa and South India, when the three parameters are considered, they have bigger posture than male. For the computational model, hybrid modelling combine finite elements and rigid bodies can be an alternative approach.

Abstract: This paper discusses a method to determine optimum numbers of kanban in Just In Time production system and analyzes effect of optimum numbers of kanban to manufacturing performance. Method to determine kanban numbers was carried out by designing kanban flow based current situation, gathering relevant parameter on floor and company database, and calculating of kanban quantity through basic mathematical model. The basic mathematical model of kanban is derived according to designated kanban flow in JIT production system. The optimum number of kanbans would control and regulate material flow in manufacturing, thus JIT is achieved. As a result, product lead time and inventory stock level are improved. The conclusion is that an appropriate determination numbers of kanban could lead to optimizing manufacturing capability.

Abstract: The purpose of this research is to investigate effect of wake splitter to pressure drop and heat transfer characteristics in a tube bank with staggered arrangements. The pressure drop and averaged heat transfer coefficient of seven rows with five tubes in each row with integral wake splitter has been determined by means of 2-D simulation using commercial computational fluid dynamics (CFD) code Fluent. Two type of integral wake splitter length have been studied, 0.5D and 1D with different location. Simulations have been carried out at Reynolds number based on tube diameter from 5000 up to 27800. The results, presented in terms of pressure drop as well as averaged heat transfer coefficient values, show the influence of wake splitter length and direction. By adding 0.5D wake splitter at downstream direction leads to higher averaged heat transfer coefficient and reduction of the pressure drop.

Abstract: This paper presents the probabilistic analysis of surface crack in round bars subjected to tension stress using Monte Carlo Simulation (MCS). A probabilistic model based on an elastic finite element analysis (FEA) was developed to evaluate the failure probability obtained using a K-estimation method. This method is based on the stress intensity factor (SIF) where the failure occurred when the SIF was assumed to exceed the critical SIF. It was found that, the K-estimation method was adequate to evaluate the failure probability of the bars when compared with the results obtained using the probabilistic FEA approach. The advantage of K-estimation methods was the reduction of the computational time and cost significantly.