Ahmad Mujahid Ahmad Zaidi

A brief review of Compressed Stabilized Earth Brick (CSEB)

Earth as a building material has already known for centuries started with plain mud and straw utilized sun dried producing brick adobe with low strength and durability until its evolved to become fired clay brick with mass rapid production in the kiln. In the growing concern of awareness regarding sustainable building material and environmental issue, Compressed Stabilized Earth Brick (CSEB) give the view of energy efficient, cost reduction and environmental friendly building materials, overall contribution on the sustainable development. It turned out that CSEB properties can be very easy bear comparison with other materials such as concrete block or normal fired brick.

Experimental Study on Ballistic Resistance of Sandwich Panel Protection Structure with Kenaf Foam as a Core Material against Small Arm Bullet

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.

Surface roughness and tool wear on cryogenic treated CBN insert on titanium and Inconel 718 alloy steel

Machining of materials by super hard tools like cubic boron nitride (cbn) and poly cubic boron nitride (pcbn) is to reduce tool wear to obtain dimensional accuracy, smooth surface and more number of parts per cutting edge. wear of tools is inevitable due to rubbing action between work material and tool edge. however, the tool wear can be minimized by using super hard tools by enhancing the strength of the cutting inserts. one such process is cryogenic process. this process is used in all materials and cutting inserts which requires wear resistance. the cryogenic process is executed under subzero temperature -186° celsius for longer period of time in a closed chamber which contains liquid nitrogen. in this research, cbn inserts with cryogenically treated was used to turn difficult to cut metals like titanium, inconel 718 etc. the turning parameters used is different cutting speeds, feed rates and depth of cut. in this research, titanium and inconel 718 material were used. the results obtained are surface roughness, flank wear and crater wear. the surface roughness obtained on titanium was lower at high cutting speed compared with inconel 718. the flank wear was low while turning titanium than inconel 718. crater wear is less on inconel 718 than titanium alloy. all the two materials produced saw tooth chips.

Effect of Uncontrolled Burning Rice Husk Ash in Foamed Concrete

Recently, foamed concrete has become a popular construction material that can be used in wide range of constructions application. Whilst the Rice Husk Ash (RHA) as agro-waste is contain high amount of silicon dioxide. RHA is produced in significant amount every year from agriculture countries. RHA has potential as a material to produce foamed concrete. In this research RHA has been used as a replacement for fine aggregate which used in construction as ordinary concrete material. In this study, foamed concrete with target density 1400, 1600 and 1800 kg/m3 has been produced. The compressive strength of foamed concrete with RHA has been tested. Concrete with Ratio 1:3 of RHA/Sand has higher compressive strength than ratios 3:1 and 2:2 of RHA/sand for every density. XRD and XRF test has been used to determinate chemical composition and crystalline structure of RHA. The result showed that RHA is an amorphous material which amorphous is important thing to pozzolanic process when hydration of cement paste. SEM and EDS test has been conducted to determine microstructure and chemical composition on microstructure of RHA foamed concrete. Amorphous RHA incorporating cement paste produces pozzolanic reaction. It is reduces the porosity and width of interfacial zone in such a way the density is increase.

Numerical Study on Failure Process of Aluminium Plate Subjected to Normal Impact by Hemispherical Projectiles

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.

Potential of RHA in Foamed Concrete Subjected to Dynamic Impact Loading

In relation to the conventional concrete then foamed concrete (FC) is weaker. Therefore FC was added by Rice Husk Ash (RHA) to alter the strength without eliminating its characteristic as aerated concrete. Actually function of RHA is substitute the sand partly. The strength of concrete affects to prevent the dynamic impact loading. However FC as aerated concrete can absorb energy impact by its porosity. Both of characteristics were presented in this investigation. SEM and EDS detected that pozzolanic reaction was done when FC was processing hydration of cement in admixture. The presence of RHA increased the strength of concrete owing to cement hydration process and pozzolanic reactivity of RHA. The result of impact loading on slab FC target displayed that FC with RHA was more shallow than without RHA. Beside of that local damage showed that FC with RHA denser and is not impression of fragments than FC without RHA.

Computational Issues in the Simulation of High Speed Ballistic Impact: A Review

This paper presents a review of recent developments of nonlinear constitutive material models for the applications in high speed ballistic impact of projectile into several types of targets. The objective is to comprehend some numerical approaches that have been proposed and used in the technical literatures especially regarding bullet-target interaction. Attention is given on the application of several types of computational constitutive models and simulations used to represent the projectile characteristic, ballistic penetration, failure modes in target and deformation pattern. This paper serves as a concise source to identify future direction in the area of computational mechanics of high speed collisions and provides brief literatures for those interested in conducting research into the topic.

Pozzolanic Characterization Of Waste Rice Husk Ash (RHA) From Muar, Malaysia

Investigation of Rice Husk Ash (RHA) thoroughly under controlled burning is regular issue to obtain result to produce the amorphous silica that has high pozzolanic reactivity characteristic. This paper offered an observation about characteristic of ground and un-ground of un-controlled burning temperature RHA that were taken from rice millings in Muar, Johor Malaysia. Such tests as X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Particle Size Analysis and Specific Area Surface, Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron microscope (SEM) were conducted in this investigation to carry out the characteristic of RHA samples. The results show that the RHA was consist approximately 89.90% of silica and the RHA possessed the amorphous particle were dominant than its crystalline part. This proves that the RHA has a big potential as a pozzolanic material considering the silica content and porous structure. In addition, particle size analysis decides whether the pozzolanic reactivity can be increased by grinding process.

Investigation on Impact Resistance Foamed Concrete Reinforced by Polypropylene Fibre

Foamed Concrete (FC) needs high strength to prevent dynamic loading, thus it is important to enhance the ductility. Usage the Polypropylene Fibre (PF) examined its contribution in strength of FC on impact resistance. Microstructures were observed that air voids in matrix of FC produce micro-porous that reduce interfacial bonding into matrix and generate micro-crack that may propagation crack growth. Presence of PF in admixture results fibrillation and reduces micro-cracks. Tensile test was investigated that PF delays crack growth in matrix. In this investigation impact test were conducted using an instrumented drop-weight impact tower. When impactor hits the target surface in free surface condition causes compressive plastic wave transform to be tensile wave. It was affected by tensile strength therefore local effect has not found spalling in crater field. In addition influence of porous in matrix FC has ability to absorb the energy and it was not found distal crack around surface area. Penetration depth results showed FC with PF subjected to impact loading was lower than without FC. Presence of PF increases FC strength and local effect results there was not impression of fragments around distal surface due to brittle crushing.

Energy Absorption Characteristics of Polyurethane Composite Foam-Filled Tubes Subjected to Quasi-Static Axial Loading

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.