Search

Polyurethane foam was synthesizes generally using isocyanate and polyol that already mix with the surfactant or catalyst as to aid polymer processing and modify properties of the polymer. Polyurethane can be divided to two types which are flexible foam and rigid foam. Usually, the flexible foam will be used in furniture industry to produce soft furniture cushioning and bedding. Rigid foam generally used for composite structured component and insulation. Main focus of this research is to produce a prediction assessment against penetration resistance of rigid polyurethane foam under specific dynamic load. Evaluation is by using analytical prediction method to evaluate the depth of penetration and energy absorption. The fabricated rigid polyurethane foam was undergoing compression test to obtain its mechanical properties and impact test to verify the prediction model with two significant measurements concerned, impact energy and the penetration depth leave by impactor. The impact speed was set up at 1.5 m/s, 1.7 m/s and 2 m/s. Results of experiment shows variations for depth of penetration and energy absorption to the predicted value from the analytical model. This variation is caused by the specimen’s rigidity disordered during the specimen producing process.

Welding operations are rarely conducted in an air-conditioned room. However, a company would set its welding operations in an air-conditioned room to maintain the humidity level needed to reduce hydrogen cracks in the specimen being welded. This study intended to assess the exposure to metal elements in the welders’ breathing zone and toenail samples. Heavy metal concentration was analysed using inductively coupled plasma mass spectrometry. The lung function test was also conducted and analysed using statistical approaches. Chromium and manganese concentrations in the breathing zone exceeded the permissible exposure limit stipulated by Malaysian regulations. A similar trend was obtained in the concentration of heavy metals in the breathing zone air sampling and in the welders’ toenails. Although there was no statistically significant decrease in the lung function of welders, it is suggested that exposure control through engineering and administrative approaches should be considered for workplace safety and health improvement.

Adsorption of Zn(II) ions from aqueous solutions by thermally treated rice husk was investigated using factorial experimental design to study effects of heating temperature and period of rice husk, pH, initial Zn(II) ion concentration, adsorption temperature and contact time, and adsorbent dosage. Main and interaction effects of these factors were analyzed using statistical techniques and the results were analyzed statistically using the Student’s t-analysis and analysis of variance which were used to determine significant factors that affect the percentage removal of Zn(II). These significant factors were heating temperature of rice husk, pH, initial metal concentration, contact time, and adsorbent dosage. The interaction between two different effects also affects the percentage removal of Zn(II) ions. These include the interactions between heating temperature of rice husk and initial metal concentration, pH and initial metal concentration, and pH and the adsorbent dosage.

In this paper a study is presented on the numerical analysis of the failure process of aluminium armour plate subjected to normal impact by hemispherical projectiles. The perforation process has been simulated by the application of 3D analysis using IMPACT dynamic FE program suite. The comparison on the elements size of meshing towards failure mode was observed and evaluated. The material behaviour of the target plate was approximated by an appropriate constitutive relation. The study covered different size of meshing element on target plate as well as different level of impact velocities. Different failure modes for each case were found. For low speed impact condition a petalling was observed, whereas for high speed impact a radial neck along with a holes enlargement was observed with better and uniform perforation mode. The deformation and failure mode of the impacted target plate will be given special attention in this investigation.

Foam-filled enclosures are very common in structural crashworthiness to increase energy absorption. However, very less research has been targeted on potential use of natural/recycled material reinforced foam-filled tubes. Therefore, an experimental investigation was performed to quantify energy absorption capacity of polyurethane (PU) composite foam-filled circular steel tubes under quasi-static axial loading. The thickness of the tubes was varied from 1.9, 2.9 and 3.6 mm. The tubes were filled with PU composite foam. The PU composite foam was processed with addition of kenaf plant fiber and recycled rubber particles that were refined at 80 mesh particulates into PU system. The density of PU resin was varied from 100, 200 and 300 kgm-3 . The PU composite foam-filled tubes were crushed axially at constant speed in a universal testing machine and their energy absorption was characterized from the resulting load-deflection data. Results indicate that PU composite foam-filled tubes exhibited better energy absorption capacity than those PU foam-filled tubes and its respective empty tubes. Interaction effect between the tube and the foam and incorporation of filler into PU system led to an increase in mean crushing load compared to that of the unfilled PU foam or tube itself. Relatively, progressively collapse modes were observed for all tested tubes. Findings suggested that composite foam-filled tubes could be used as crashworthy member.

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 experiment’s 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.

This paper reports recent findings of a research programme focused on the carbonation and permeability of foamed concrete. The objective is to develop an environmentalfriendly and economical material for sustainable construction on peat. A four-year study showed that the rate of carbonation is related to the permeability, time and density. A water permeability test system has been developed based on ISO/DIS7031 and a draft standard prepared. They are aimed at promoting concrete durability research. It features a dual-test method for the measurement of water permeability with the standard 150 mm test cube prior to the determination of compressive strength. The calibration of the test system is by means of a mature test cube of known water permeability. The test system plays complementary role to the existing methods of assessing durability such as carbonation test and rapid chloride permeability. The test method is non-destructive, convenient and reliable for assessing concrete durability in the laboratory at the mix design stage. It can be used subsequently for tests on concrete products and structures for rain water harvesting system. Information technology has been experimented to provide online skill training and the electronic publications of research findings to promote good concrete practice via a concrete innovation blog http://www.1.net.my and a concreteresearch portal http://www.it-lodge.com.

Quasi static indentation test is a method consist of applying a compressive axial load using head of indenter to moulded cylinders at a rate which is within a prescribe range until failure occurs. The behaviour of foamed concrete under indentation test should behave like cellular material behavior. The Stress-strain behavior can be divided into three regimes, elastic regime, plateau regime and densification regime. There is still less research conducted toward foamed concrete under indentation test. It is stated that the standard method to obtain the compressive strength of foamed concrete based on ASTM C39 standard or BS 1881: Part 116:1983 is not captured the true compressive strength of foamed concrete. The compressive strength typically achieved low compressive strength and not behaves like a cellular material behavior. This result is due brittle collapse of the sample. Previous study has shows the compressive strength under indentation test is higher and created a localized deformation. Besides, there is a densified zone created below the indenter region which is end with hemi-spherical shape. . Tear line occur because of exrended in front of the indenter and perpendicular to the indenter surface. This study aims to investigate further about the behavior of foamed concrete. This study was look about effect of densities and size of indenter on behavior of foamed concrete under indentation test. The density used is low density, medium density and high density. Size of indenter used is 20mm, 30mm, 50mm and 70.5mm. Under indentation test, the higher densities, the higher compressive strength and the bigger size of indenter used, the strength is decreased due to the early crack initiation and propagation. It is important to know the ratio used to make sure indentation test is captured the true strength.

Concrete is basic construction material used for almost all kind of structure. However, in the majority essential structures such as nuclear plants, Power plants, Weapon Industries, weapons storage places, water retaining structures like dams, highways barriers, bridges, & etc., concrete structures have to be designed as self-protective structure which can afford any disaster or consciously engendered unpleasant incidents such as incident occurs in nuclear plants, incident in any essential industry, terrorist attack, Natural disasters like tsunami and etc missile attack, and local impact damage generated by kinetic missiles dynamic loading (steel rods, steel pipes, turbine blades, etc.). This paper inquisitively is paying attention on verdict of the recent development in formulating analytical behavior of concrete and reinforced concrete structures against local impact effect generated by hard missile with and without the influence of dimensional analysis based on dominant non-dimensional parameters, various nose shape factors at normal and certain inclined oblique angles. The paper comprises the analytical models and methods for predicting penetration, and perforation of concrete and reinforced concrete. The fallout conquer from this study can be used for making design counsel and design procedures for seminal the dynamic retort of the concrete targets to foil local impact damage.

Concrete is basic construction material used for any kind of structure. However, in most vital and local structures such as nuclear plants, Power plants, Weapon Industries, weapons storage places, water retaining structures like dams, and also local industries, & etc., concrete structures have to be designed as defensive structures to provide protection against any accidents or knowingly generated incidents such as dynamic loading, dynamic local impact damage and global damage generated by kinetic missiles (steel rods, steel pipes, turbine blades, etc.). The impacting missile (projectile) can be classified as ‘Hard’ and ‘Soft’ in nature, depending upon the implication of its deformation with respect to the deformation of target. ‘Hard’ missile impact can generate both local impact damage and also overall dynamic global damage of concrete structure. This paper only provides the review of previous empirical studies related to our study and can be used for making design recommendation and design procedures for determining the dynamic response of the target to prevent local and impact damage.

The current usage level of wind power as alternative source of energy in Malaysia is very low. Ironically, some areas particularly coastal area has steady wind energy supply that is potential to generate electricity for residential use. There is urgent need to locally develop the low cost wind turbine generator that has the capability to not only supply electricity to respective household but can be connected to power grid so that excess power could be sold back to the local utility company. Recent developments of power electronic converters allow stable supply needed for grid transfer in respect to nature of wind dynamics, enhanced power extraction and low total harmonic distortion (THD). In this project, an inverter circuit with suitable control scheme design is developed to be used with a 500W permanent magnet type wind generator which is typical for residential use. Expected circuit output is single phase 240V sine wave voltage which is nominal grid voltage with the total harmonics distortion (THD) of voltage across load should not exceed 5% as recommended by IEEE Standard 519-1992. The simulation and experimental results are included in the paper.

In this paper the energy absorption of kenaf foam filled cylindrical tube has been investigated. First, a finite element model for empty cylindrical tube was constructed and followed by a foam-filled cylindrical tube model. In this study, there were five samples of kenaf foam density that been used and they are 5%, 10%, 15%, 20% and 0% (100%PU) for three different thickness cylindrical tube. The implemented models were used to simulate the behavior of empty and foam-filled tubes under lateral dynamic loadings. An impact mass of 10kg with three different impact velocity, 10m/s, 15m/s and 20m/s were used in the empty tube model simulation. Meanwhile, for foam-filled tube, impact velocity had increased to10m/s, 20m/s and 30m/s. The energy absorption capability was increased with foam filler in the cylindrical tube and the best kenaf foam density was obtained at 15%. For 15% kenaf foam, the value of energy absorption was higher than 100% PU but the energy absorption decreases for 20%.The results showed that increases wall thickness and kenaf foam filler will increase the energy absorption.