Muhd Hafeez Zainulabidin

Effect of Velocity on the Impact Resistance of Woven Jute Fiber Reinforced Composites

is present project investigated the impact penetration response of woven jute fiber reinforced composites subjected to wide range of low impact velocities. Hand layout woven jute fibers are thermally compressed to ensure no internal defects formed in the composites. Six layers of woven jutes are stacked together using different fiber orientations [0/q/0]s. Low impact velocities are used ranging between 5 – 20 m/s. Force-time, force-displacement and energy-time curves are obtained automatically during the impact tests. The results are then discussed with considering the composite fragmentations and failure mechanisms. It is found that 00 composite orientations capable to absorb sufficiently impact energy for 5 m/s but not for velocity greater than 10 m/s. When fiber orientations used between 15 – 450, the composite impact resistance increased indicating two significant peak forces. These peak forces represent different type of failure mechanisms occurred during the striker progresses.

A Review on Effect of Orientation Fabric on Mechanical Energy Absorption Natural Fibres Reinforced Composites

This paper presents the combination technique in developing the woven kenaf fiber that is used as a new method to improve energy absorption performance. This method focuses on the effect energy absorption of angle orientation. Due to the low density, natural fiber such as kenaf fiber provides comparatively good mechanical properties. Thus, natural fibers have high potential for better reinforcement in light weight structures on automotive applications. Total force, total energy, and energy absorption of natural fibre reinforced composite for different type’s natural fibre and angle orientation are discussed and reviewed.

Vibration Analysis of a Beam Structure Attached with a Dynamic Vibration Absorber

In this paper the transverse vibration of a fixed-fixed end beam will be investigated by experimental measurement. This paper is concerned with the classical theory formula as well as the analysis and design of the dynamic vibration absorber (DVA) which is composed by a flexible beam with two masses symmetrically mounted at its both sides. The fixed end beam clamped to a static structure where dynamic vibration absorber then being attached onto it. One side of end of the beam is harmonically excited in transversal direction by an electric shaker. The structure equipped with accelerometer sensor to measure its vibration response amplitudes and natural frequencies. The dynamic vibration absorber arrangement located under motor near the beam end was then being vibrated and done in two conditions; before and after mounting dynamic vibration absorber. The comparison amplitudes before and after equipped dynamic vibration absorber were compared and discussed. From the experimental results, proved that the DVA has successfully absorbed the beam vibration hence reduced the vibration amplitude of the beam structure. The knowledge and result obtained from this study can help engineers control the vibration level of beam structure.

Optimization of Sound Absorbers Number and Placement in an Enclosed Room by Finite Element Simulation

Giving a room proper acoustic treatment is both art and science. Acoustic design brings comfort in the built environment and reduces noise level by using sound absorbers. There is a need to give a room acoustic treatment by installing absorbers in order to decrease the reverberant sound. However, they are usually high in price which cost much for installation and there is no system to locate the optimum number and placement of sound absorbers. It would be a waste if the room is overly treated with absorbers or cause improper treatment if the room is treated with insufficient absorbers. This study aims to determine the amount of sound absorbers needed and optimum location of sound absorbers placement in order to reduce the overall sound pressure level in specified room by using ANSYS APDL software. The size of sound absorbers needed is found to be 11

Modelling of Rigid Walled Enclosure Couple to a Flexible Wall using Matlab and Ansys APDL

Generally, solutions to improve the noise problems in enclosure are to redesign or modifying the system such as increasing the thickness of the wall panels, enhancing the elasticity of the structure, and increase the damping mechanism of the wall structure. In this paper, the application of vibroacoustic modelling of enclosure coupled to a flexible wall was presented. The sound pressure characteristics of rigid walled enclosure, such as natural frequency and mode shape were determined using two approaches which are finite element simulation of Ansys® and mathematical model. The mathematical equations derived in Matlab® such as rigid walled enclosure and rigid walled enclosure coupled to flexible wall were used to validate finite element analysis (FEA). The result indicates that the theory and FEA display in a good agreement. Thus, proved that the FE model was accurate and can be applied in further research such as sound pressure and noise attenuation in enclosure.

Assessment and Evaluation for Programme Learning Outcomes in Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia

Universiti Tun Hussein Onn Malaysia (UTHM) is the 15th of the 20 public universities established in Malaysia. UTHM consists of eight faculties. One of them is the Faculty of Mechanical and Manufacturing Engineering (FKMP). The programme offered – Bachelor of Mechanical Engineering with Honours (BDD), undergoes continuous auditing and accreditation by the Engineering Accreditation Council (EAC). To fulfill the requirement for accreditation, EAC requires the faculty to assess and evaluate the programme learning outcomes’ (PLOs) attainment of the graduates, such that all graduates are targeted to achieve the performance indicator (PI) upon graduation. This paper discusses the methods developed by the FKMP for PLOs’ measurement and evaluation. Two approaches are utilized in this regards, (i) the direct assessment based on students’ performance in courses, and (ii) the indirect assessment based the industrial and graduates’ perception. The PLOs’ attainment for graduates of cohort 2010-2012 are analysed in this study. Consolidation data shows that the PI for majority of the PLOs are achieved, indicating that the programme offered complies with the standard expected by different stakeholders.

Stress intensity factors and interaction of two parallel surface cracks on cylinder under tension

This paper presents three-dimensional (3D) finite element solution on multiple surface cracks. The cracks on solid cylinder are similar in sizes, parallel each other, assumed to grow in semi-elliptical shape and subjected to remotely tension loading (mode I). A wide range of parametric study involving crack depth ratios ( 0.1<a/D<0.4), crack aspect ratios (0.2<a/b<1.2), normalized coordinates on crack front (0.0<x/h<0.93) and inter-crack distance ratios (0.005<c/l<0.32) are considered for numerical estimation of stress intensity factors (SIFs) along crack front. For multiple surface cracks under axial loading, the stress intensity factors along crack front decreased when c/l decreased. When multiple cracks approach one another, the stress intensity changes due to interaction of the stress field. The results show that it produces a stress shielding effects.

Optimization on Impact Strength of Woven Kenaf Reinforced Polyester Composites using Taguchi Method

This paper focuses on the effect of weaving patterns and orientations on the energy absorption of woven kenaf reinforced polyester composites. Kenaf fiber in the form of yarn is weaved to produce different weaving patterns such as plain, twill and basket. Three woven mats are stacked together and mixed with polyester resin before it is compressed to squeeze out any excessive resin. There is nine different orientations are used during stacking processes by following Taguchi orthogonal arrays method. The hardened composites are cured for 24 hours before it is shaped according to specific dimensions for impact tests. The composites are perforated with 1m/s blunted projectile. According to the experimental findings, weaving pattern and orientation have distinct potential effects on value of energy absorption. The optimization using Taguchi method reveals preferable orientation of each weaving pattern composites. Based on the fracture observation, the fragmentations after optimization indicating lower distance surface fracture perforated obtained.

Effect of Porous Materials Combination in Layers on Sound Absorption Characteristics

This paper describes the investigation and analysis on two materials in which one material is a relatively good sound absorber at low frequency range and another is a relatively good sound absorber at high frequency range, combined together in layers to form a better sound absorber for a wider range of frequencies. The layer combinations of the materials are varied and the values of Sound Absorption Coefficient, α are measured experimentally by using impedance tubes with two microphones transfer function method according to ISO 10534-2 standard. The results obtained are compared in terms of the order of material and the number of layer combinations of materials for each sample. The orders of combinations and number of layers of combinations have significant influence on the sound absorption characteristics. The order of materials has reversed effect on Sound Absorption Coefficient, α as the number of layer combination is increased. Increase in the combination number will make the specimen performed relatively better at a wider frequency range.

Surface Tension Effect on Sound Absorption Characteristics of a Cavity-Backed Semi-Permeable Membrane

This paper describes the analysis on the characteristics of semi-permeable membrane sound absorber. The effects of membrane surface tension on the sound absorption characteristics were investigated. The characteristics of the membrane absorber was measured experimentally in terms of Sound Absorption Coefficient, α and Noise Reduction Coefficient, NRC. The membrane is made of thin, flexible, semi-permeable latex material and the tests were carried out by using impedance tube method according to ISO 10534-2 standard. The results showed that the surface tension has significant influence on the sound absorption characteristics. For the parameters used in the laboratory work, specimen with unstretched surface tension has the best absorption performance.