M. R. M. Rejab

Investigation on modal transient response analysis of engine crankshaft structure

The crankshaft is a very crucial part in an internal combustion engine. This paper presents the findings of the mode shape and natural frequency of 3 cylinder 4 stroke engine crankshafts. Both experimental and computational methods were carried out to determine the modal parameter or dynamic characteristics, which are natural frequency, damping factor and mode shape. The prediction of the dynamic properties of the chassis is of great significance in determining the natural frequencies of the structure. The experiment is done by using an impact hammer to excite the crankshaft and data is recorded using a data acquisition system (DAS) connected to a sensor located on the crankshaft. Computational modal analysis on the crankshaft structure is simulated using finite element software. It can be seen from the results that there is a good agreement between the experimental and computational results in terms of modal parameter with a small discrepancy. The modal analysis techniques are essential for automotive crankshaft structure design.

Tensile Properties of Hybrid Sugar Palm/Kenaf Fibre Reinforced Polypropylene Composites

Study on hybridization of two types of natural fibres reinforced thermoplastic composites was an alternative option in research on natural composites. This paper presents the investigation on tensile properties of combining sugar palm and kenaf fibres reinforced polypropylene composites. The hybrid composites were prepared with different amounts of fibres (i.e. 10%, 20% and 30% by weight percent) while the ratios between sugar palm and kenaf fibre are 30:70, 50:50 and 70:30. The composites have been fabricated using melt mixer technique and followed by compression molding process. The specimens were cut according ASTM Standard D638 for conducting the tensile testing. The results shown that tensile strength of composites tend to decreased when the content of loading fibres increased. Among the composites with different ratios, the hybrid composites that contain more kenaf fibres exhibit the higher value in tensile strength than the composites that contain more sugar palm fibres.

Mechanical Behaviour of Polymeric Foam Core at Various Orientation Angles

Polymeric foam is widely used as core materials in various applications such as cushioning, padding, insulating, structural use and buoyancy. This is because of its ability to provide high bending stiffness tied with lightweight in composite sandwich construction. The purpose of this paper is to present the behaviour of polyurethane foam, which is fabricated in various orientation angles. Five different orientation angles have been studied i.e. 0o, 30o, 45o, 60o and 90o. Three mechanical tests were performed under tension, compression and shear loads to investigate the polyurethane foam (PU) behaviour. Electron microscope was used to capture the microstructure of the specimens before and after the tests. Comparisons have been made between different orientation angles in fracture modes and mechanical properties. Deformation and failure occur during foam crushing are discussed according to experimental evidence. Since the main application of foam materials are for energy absorption, foam response under considerable compression has been studied intensively. At angle of 90o, it permits more localised failure with high-energy absorption and in contrary, 0o which posses the lowest of energy absorption. Energy absorption for PU foam material tends to increase when the orientation of angle is increased.

Tensile Properties of Pineapple Leaf Fibre Reinforced Unsaturated Polyester Composites

In recent years natural fibres such as sisal, jute, kenaf, pineapple leaf and banana fibres appear to be the outstanding materials which come as the viable and abundant substitute for the expensive and non-renewable synthethic fibre. This paper investigate the effect of fibre length and fibre content on the tensile properties of pineapple leaf fibre (PALF) reinforced unsaturated polyester (UP) composites. PALF as reinforcement agent will be employed with UP to form composite material specimens. The various of fiber length (<0.5, 0.5–1, and 1-2 mm) and fibre content (0, 5, 10 and 15 % by volume) in UP composite have been studied. The fabrication of PALF/UP composites used hand lay-up process, and the specimens for tensile test prepared follow the ASTM D3039. The result obtained from this study show that the 1-2 mm fibre length has higher tensile strength (42 MPa) and tensile modulus (1344 MPa) values compared to fibre length of <0.5 mm (30 MPa and 981 MPa) and 0.5-1 mm (35.40 MPa and 1020 MPa) respectively. Meanwhile, for the effect of various fibre content in study has shown that the increase of fibre content has decreased in tensile strength dan tensile modulus of composites. The increase of fibre content due to poor interfacial bonding and poor wetting of the fibre by unsaturated polyster. The treatment of natural fibre are suggested in order to improve the interfacial adhesion between natural fibre and the unsaturated polyester.

Prediction Modelling of Surface Roughness for Laser Beam Cutting on Acrylic Sheets

This paper develops the predicting model on surface roughness of laser beam cutting (LBC) for acrylic sheets. Box-Behnken design based on Response surface method was used to predict the effect of laser cutting parameters including the power requirement, cutting speed and tip distance on surface roughness during the machining. Response surface method (RSM) was used to minimize the number of experiments. It can be seen that from the experimental results, the effects of the laser cutting parameters with the surface roughness were investigated. It was found that the surface roughness is significantly affected by the tip distance followed by the power requirement and cutting speed. Some defects were found in microstructure such as burning, melting and wavy surface. This simulation gain more understanding of the surface roughness distribution in laser cutting. The developed model is suitable to be used in the range of (power 90 to 95, cutting speed 700 to 1100 and tip distance 3 to 9) to predict surface roughness.

Mechanical Properties of Mengkuang Leave Fiber Reinforced Low Density Polyethylene Composites

Mengkuang (Pandanus tectorius) grows abundantly in the coastal region of Southeast Asia. To date, the application of mengkuang leaves fiber (MLF) as reinforcement in polymer matrix is still limited in literature making its potential as reinforced material remain unknown. Therefore, this chapter focuses on the tensile properties, flexural, and impact properties of (MLF)/LDPE composite fabricated through the hot compression machine. In this study, the effect of volume fraction, fiber length of MLF was investigated. Two main groups of MLF/LDPE composite samples were established. The first group consists of different fiber mesh size range (<0.5 mm, 0.5–8 mm, and 1–2 mm) with constant volume fraction (10 wt%) while in another group volume fraction is varying (10, 20, and 30 wt%) but constant fiber length (<0.5 mm). Further investigation was conducted by treating the MLF/LDPE composite of volume fraction 30 wt% and fiber length 0.5 mm with maleic anhydride polyethylene (MAPE) with loading content of 2, 4, and 6 wt% The surface fracture of each samples was analyzed via scanning electron microscope. The result from both groups is compared to the pure LDPE. From the result, it can be concluded that both volume fraction and fiber length do not improve tensile properties and impact properties of MLF/LDPE composite. However, the flexural strength of MLF/LDPE increased significantly. A similar result was obtained when MLF/LDPE composite was treated with the MAPE.

A Comparison of Muscular Activity among European, Korea and Malaysian During Seating Using Musculoskeletal Computational Analysis Method

Sitting is the most common posture in any industry field either in office work, manufacturing or even automotive. Sit for a long time lead to musculoskeletal disorder which causes muscle fatigue. However, different size of people will have a different level of muscle activation. The objective of this paper is to analyse and compare the muscle activation during sitting among European, Korean, and Malaysian. The human size employed for this study is by 95th percentile male. The AnyBody Modelling Software is used to simulate and analyse the human muscle activity of the seating posture of these respective countries. Our finding showed that the trunk of the human body has the highest muscle activity. The Malaysian anthropometry showed the highest muscle activity in sitting posture; followed by Korean and European.

Specific Properties of Novel Two-Dimensional Square Honeycomb Composite Structures

Hexagonal honeycomb cores have found extensive applications particularly in the aerospace and naval industries. In view of the recent interest in novel strong and lightweight core architectures, square honeycomb cores were manufactured and tested under uniform lateral compression. A slotting technique has been used to manufacture the square honeycomb cores based on three different materials; glass fibre-reinforced plastic (GFRP), carbon fibre-reinforced plastic (CFRP) and self-reinforced polypropylene (SRPP). As semi-rigid polyvinyl chloride (PVC) foam was placed in each of unit cells to further stiffen the core structure. The core then was bonded to two skins to form a sandwich structure. The compressive responses of the sandwich structures were measured as a function of relative density. In this paper, particular focus is placed on examining the compression strength and energy absorption characteristics of the square honeycombs with and without the additional foam core. Comparisons in terms of specific strength and specific energy absorption have shown that the CFRP core offers excellent properties. The presence of the foam core significantly increases the energy absorption capability of overall structure and the SRPP core could potentially be used as an alternative lightweight core material in recyclable sandwich structures.

Prediction Modelling Of Power And Torque In End-Milling

This paper presents the development of mathematical models for torque and power in milling 618 stainless steel using coated carbides cutting tool. Response surface method was use to predict the effect of power and torque in the end-milling. From the model, the relationship between the manufacturing process factors including the cutting speed, feed rate, axial depth and radial depth with the responses such as torque and power can be developed. Beside the relationship, the effect of the factors can be investigated from the equation developed. It can seen that the torque increases with decreases of cutting speed while increase of the feed rate, axial depth and radial depth. The acquired results also shown that the power increases with the increases of cutting speed, feed rate, axial depth and radial depth .It can be found that the second order is more accurate based on the variance analysis and the predicted value is closely match with the experimental result. Third- and fourth- order model generated for both response to investigate the 3- and 4-way interaction between the factors. The third and fourth order model shows that 3- and 4-way interaction found less significant for the variables.

Development of Statistical Model to Predict Ra and Rz in the Laser Cutting

Laser cutting is one of the advances machining on material remover process.This paper explores the prediction model of surface roughness (Ra) and roughness height (Rz) of laser beam cutting on acrylic sheets. Box-Behnken design based Response Surface Method (RSM) was used to predict the effect of laser cutting parameters which are laser power, cutting speed and tip distance on Ra and Rz. The predictive models are good agreement with experimental results. The first order equation revealed that the power requirement was the dominant factor followed by tip distance and cutting speed respectively. This observation indicates that the potential of using RSM in predicting cutting parameters thus eliminating the need for exhaustive cutting experiments to obtain the optimum cutting condition and enhance the surface roughness.