Laila Majid - Academia.edu (original) (raw)

Papers by Laila Majid

Microsystem Technologies, 2020

Shape memory alloys (SMAs) have been considered as actuators for micro application due to its hig... more Shape memory alloys (SMAs) have been considered as actuators for micro application due to its high strength to weight ratio. Although it is mostly considered for linear or rotary actuation, in this study a technique using a temperature feedback control system has been proposed to produce oscillation at steady state suitable for flapping wing actuation in micro air vehicles (MAVs). A proportional-integral-derivative (PID) controller was used in the temperature feedback system to tune the frequency of oscillation of the shape memory alloy actuator. This system is compact as the oscillation can be produced without using components to translate from linear to rotary motion. Another challenge to be addressed is the slow cooling rate of the SMA actuator that occurs through natural convection resulting in slower flapping actuation. Thus, a viable approach to improve the actuation response is by coating the SMA to reduce hysteresis. An experimental study was conducted to evaluate the effects of heat convection on the SMA actuator's control performance by using SMA wire coated with silicone rubber. Its actuation was compared to the uncoated SMA wire to establish the effects of heat convection on SMA actuation behaviour. The response of the temperature feedback system of the SMA actuator for the flapping actuation under wind loading was evaluated using wind tunnel testing. The experimental results show that coated SMA wire resulted in increased actuation frequency. However, this effect became negligible as the airflow provided sufficient cooling and resulted in higher flapping frequency at Reynolds number greater than 7.5 9 10 3. Wind tunnel testing demonstrated that shape memory alloy actuators using a PID based temperature feedback control system may be used to produce flapping actuation at low Reynolds numbers.

There is a fast-growing interest to monitor the dynamic behavior of cable stayed bridges due to t... more There is a fast-growing interest to monitor the dynamic behavior of cable stayed bridges due to their long spans leading to complexity of their structures. These bridges are evolved for a long term structural health monitoring method since their performance is challenged with mixture type of traffic loading daily. This paper is aimed to propose sensors positioning at dead load condition. Finite element analysis is effective and accurate approach to certain extend used to determine the highly stressed grid points due to vibration of the bridge members. The bridge in concern is cable stayed Harp type of Penang (I) bridge. The findings based on analytical modal analysis reveals that the number of sensors to be positioned were 66 locations of the cable stayed bridge.

Journal of entomology and zoology studies, 2016

Brown planthopper (BPH) Nilaparvata lugens is an imperative insect pest of rice crop throughout t... more Brown planthopper (BPH) Nilaparvata lugens is an imperative insect pest of rice crop throughout the Asia. Both BPH male and female rely on substrate borne vibrational signals prior to mate. Often such mating communication is affected by rivalry signals of other existed males of variable age and population. Therefore, the current study observed the effect of age and population density on production of male rival calls. The results illustrated that the male rival calls were only produced in the presence of other male. No single male rival call was produced when a pair of a matured male and female of five days old was placed on rice plant. However, production of rival calls increased with increasing the age of BPH male and maximum number of (90%) male produced rival calls at the age of fifth days. Similarly, the population density affected the behaviour of male for producing the rival calls. A maximum number of male produced rival calls, when population of seven virgin males were reare...

The purpose of this case study is to analyse the effect of the stacking sequence and lay-up orien... more The purpose of this case study is to analyse the effect of the stacking sequence and lay-up orientation of the fiber of laminated composite materials employing plain weave C-glass fibres with varying fibre densities. The study was divided into two parts which are simulation and experimental analysis. Through the simulation analysis, three designs were proposed and the best design with the highest UTS was chosen to be fabricated in order to validate the simulation results. All designs are symmetric in terms of angle of orientation which only utilized 00/900 and ±450 plies. The simulation analysis were performed using ABAQUS and the finite element model was simulated in a non-linear mode with displacement of 3mm. The second part of this study is to fabricate the best design with the highest UTS based on the ABAQUS analysis. The specimen was fabricated through hand lay-up method before being cut into a rectangular shaped coupon with standard dimensions according to ASTM D3039. The prep...

Aerodynamics and structure measurement subsystem for a shape memory alloy actuated adaptive airfoil

The aim of this study is to propose a subsystem that is able to establish correlation between aer... more The aim of this study is to propose a subsystem that is able to establish correlation between aerodynamics and structure measurements to be used as the input to the existing shape memory alloy actuated adaptive airfoil system. A reconfigurable wing with NACA 4412 airfoil was fabricated using Acrylonitrile Butadiene Styrene (ABS) and actuated using SMA spring. A wind tunnel testing was conducted at low Reynolds number with angle of attack ranging from 0° to 12°. Pressure taps were fitted along the upper and lower surface of the airfoil and connected to the multi-tube manometer in order to obtain pressure measurements and strain gauges were mounted in parallel to the pressure taps on the upper surface to measure the deflection of the structure due to the aerodynamics loading. A system to compute the lift and drag coefficients from pressure measurements, was developed using LabVIEW software. The strain of the airfoil structure on the upper surface of the airfoil was measured using stra...

Crystals, 2021

Fly ash is the main waste as a result of combustion in coal fired power plants. It represents abo... more Fly ash is the main waste as a result of combustion in coal fired power plants. It represents about 40% of the wastes of coal combustion products (fly ash, boiler ash, flue gas desulphurization gypsum and bottom ash). Currently, coal waste is not fully utilized and waste disposal remains a serious concern despite tremendous global efforts in reducing fossil fuel dependency and shifting to sustainable energy sources. Owing to that, employment of fly ash as reinforcement particles in metallic matrix composites are gaining momentum as part of recycling effort and also as a means to improve the specifications of the materials that are added to it to form composite materials. Many studies have been done on fly ash to study composite materials wear characteristics including the effects of fly ash content, applied load, and sliding velocity. Here, particular attention is given to studies carried out on the influence FA content on physical, mechanical, and the thermal behavior of Aluminium-...

Journal of Materials Research and Technology, 2020

Shape memory alloys (SMA) are reputable for their capability of regaining shape at certain temper... more Shape memory alloys (SMA) are reputable for their capability of regaining shape at certain temperatures even after large deformations. In the martensite phase, when a load is applied on SMA wire, it accommodates strain rather than breakage by unfolding its lattice that results in improving damping and stiffness. Also, SMA generates stresses due to phase transformation from martensite to austenite at higher temperatures. This coupling effect of SMA in response to load and temperature makes its use for improving properties of composites by embedding in composite structures. The major factor considered during embedding SMA wires into composite structures is the compatibility between SMA and matrix. SMA wires should have excellent adhesion with matrix otherwise, cracking and delamination in the composite will occur. Therefore, different techniques are carried out for surface modification of SMA wire to improve the bonding between matrix and SMA wire. These techniques are expensive, time-consuming and sometimes give undesirable results. An alternative approach used in this research is to weave SMA wires in 3D structures for providing better grip to these wires before composite fabrication. 3D structures have higher through-the-thickness properties and delamination resistance, but their inplane properties are lower than 2D laminated composites. Due to the weaving of SMA wires into 3D structures, binder yarns provide a better grip to SMA wire that ultimately increases the interfacial strength of composite while SMA wire improves the tensile properties of 3D structures. Results show that a single SMA wire embedded in three different 3D configurations contributes in improving the tensile properties of each 3D structure depending on the interlocking behavior of fibers with SMA wire. The layer-to-layer 3D configuration loosely grips SMA wire, hence SMA wire faces less resistance upon activation and improves Young's Modulus to 34.9%. The modified 3D structure provides a strong grip to the SMA wire, hence limitise the increment of Young's Modulus to 16.06%. Tensile behavior along with structural failures of SMA embedded 3D woven composites are discussed in detail.

Crystals, 2020

Lightweight, high-strength metal matrix composites have attracted considerable interest because o... more Lightweight, high-strength metal matrix composites have attracted considerable interest because of their attractive physical, mechanical and tribological properties. Moreover, they may offer distinct advantages due to good strength and wear resistance. In this research, AA6063 was reinforced with FA particles using compocasting methods. The effects of fly ash content, load, sliding speed and performance tribology of AA6063 –FA composite were evaluated. Dry sliding wear tests were carried out according to experimental design using the pin-on-disc method with three different loads (24.5, 49 and 73.5 N) and three speeds (150, 200 and 250 rpm) at room temperature. Response surface methodology (RSM) was used to analyze the influence of the process parameters on the tribological behavior of the composites. The surface plot showed that the wear rate increased with increasing load, time and sliding velocity. In contrast, the friction coefficient decreased with increasing these parameters. O...

The Journal of The Textile Institute, 2019

Shape memory alloys (SMAs) are capable of shape-retaining and stress generation when activated. S... more Shape memory alloys (SMAs) are capable of shape-retaining and stress generation when activated. SMA wires are embedded in laminated composites for improving the properties of the composites. Laminated composites have low through-the-thickness properties and poor delamination resistance. 3D composites are well known for having higher through-thethickness properties. In 3D woven composites, a set of yarn is in through-the-thickness direction that improves through-the-thickness properties and provides resistance to delamination of layers. As in multilayer 3D woven structures, yarns are distributed from inplane to through-the-thickness direction, so in-plane properties are reduced with the same number of yarns compared to 2D laminated composites. In this research, SMA wires are embedded into different types of 3D woven structures for utilising stress generation property of SMA wires for improving in-plane properties, specifically stiffness of the composites. Three types of 3D orthogonal interlocking composites: layer-to-layer, through-the-thickness, and modified multilayer interlock structures are fabricated with and without SMA wires. From the tensile test, results show that embedding SMA wires into structures significantly improves the stiffness of the structures due to the stress-induced martensite phase of SMA wire when subjected to load. When these SMA wires are activated, stresses are generated by SMA wires due to phase transformation from martensite to austenite that further gives remarkable higher values of stiffness. This results in a composite structure that has higher inplane properties due to embedded SMA wire and through-the-thickness properties due to 3D structure of composite reinforcement. The interlocking pattern in the through-the-thickness direction of 3D structures was also found to have an effect on the extent of the improvement in stiffness.

Metals, 2017

Aluminum-fly ash particulate-reinforced composites (AA6063-FA) have been used in various engineer... more Aluminum-fly ash particulate-reinforced composites (AA6063-FA) have been used in various engineering fields, such as automotive and aerospace industries, due to their low density and good mechanical properties. There are many fabrication techniques available to manufacture these composites according to matrix and reinforcement materials. The compocasting technique for the fabrication of the AA6063 matrix composite reinforced with fly ash particles is the focus of this research. Fly ash content was in the range of 0-12 wt % in increasing increments of 2%. Fly ash particles were added to the molten AA6063 alloy until they were completely blended and cooled down just below the liquidus to keep the slurry in the semi-solid state. After this, the molten AA6063-FA composites were cast into prepared cast iron molds. Bulk density and apparent porosity measurements, Charpy impact testing, Vickers microhardness measurements, Field Emission Scanning Electron Microscope (FESEM), Variable Pressure Scanning Electron Microscope and Energy Dispersive X-ray spectroscope (EDS) elemental mapping were used to evaluate these materials. The results showed that an increase in the fly ash content in the melted leads results in an increase in the microhardness and porosity in the composites. In contrast, the bulk density and Charpy impact energy of the composites decreased with an increase in the fly ash content.

Materials Express, 2019

Fly ash (FA) has collected attention as a possible reinforcement material for aluminium matrix co... more Fly ash (FA) has collected attention as a possible reinforcement material for aluminium matrix composites (AMCs) to improve the properties and decrease the production cost. In this study, AA6063 alloy was reinforced with FA particles by compocasting technique. The experiments were conducted by varying weight percentage of FA (0 to 12 wt.% in steps of 2%). The FA particles were incorporated into semisolid state of AA6063 alloy melt. The microstructure of aluminum-FA particulate composite (AA6063-FA) prepared with the homogenous distribution of FA was analyzed using X-ray Diffraction (XRD), Energy Dispersive X-ray spectroscopy analysis, Variable pressure scanning electron microscope (VPSEM) and Field emission scanning microscope (FESEM). The mechanical and thermal properties of the composites were determined with a tensile, compressive and thermal expansion tests. The experimental results indicated that the microstructure, mechanical and thermal properties of AA6063-FA composites were observably affected by increasing FA content. The fracture surface was observed to be different in the failure mechanism.

BioResources, 2018

The goal to decrease global dependency on petroleum-based materials has created a demand for bio-... more The goal to decrease global dependency on petroleum-based materials has created a demand for bio-based composites. Composites that are reinforced with natural fibers often display reduced strength compared with those using synthetic reinforcement, and hybridizing both types of reinforcement within a common matrix system offers a possibly useful compromise. This research investigated the low-velocity impact performance of glass, kenaf, and hybrid glass/kenaf reinforced epoxy composite plates. The aim of the study was to determine the low-velocity impact behavior of biocomposite material in assessing its potential for application in the radome structures of aircraft. Natural fibers possess low dielectric constants, which is a primary requirement for radome. However, the structural integrity of the material to impact damage is also a concern. Composite samples were prepared via a vacuum infusion method. A drop weight impact test was performed at energy levels of 3 J, 6 J, and 9 J. The Impact tests showed that the impact peak force and displacement increased with the energy level. Hybrid glass/kenaf composites displayed damage modes of circular and biaxial cracking. The former is analogous to the damage observed in glass-reinforced composite, while the latter is unique to woven kenaf reinforced composites. The severity of the damage increased with impact energy and was found to be significant at 3 J.

IOP Conference Series: Materials Science and Engineering, 2018

The AA6063 alloy reinforced with 0, 2, 4 and 6 wt. % of fly ash (FA) particulate composites were ... more The AA6063 alloy reinforced with 0, 2, 4 and 6 wt. % of fly ash (FA) particulate composites were produced by the compocasting technique. In this study, the effect of FA content and sliding speed on the wear behaviour of AA6063-FA composite was investigated. The wear was carried out by using pin on disc apparatus against rough steel counterface. These wear tests were conducted at applied load of 24.5, 49 and 73.5 N respectively with the constant sliding speed (150 rpm) and sliding time (10 minutes). In the results, it has been observed that upon addition of FA particles, the wear resistance of AA6063 -FA composites was enhanced. The wear rate reduced with the increase in the content of FA particles. While the wear rate increased with increase in the applied load.

Journal of Material Science & Engineering, 2013

In the current study, the effects of stacking sequence layers of hybrid composite materials on ba... more In the current study, the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption, which were fabricated from Kevlar, carbon, glass fibres, and resin have been experimentally investigated at the high velocity ballistic impact conditions. All the samples have equal mass, shape, and density, nevertheless, they have different stacking sequence layers. After running the ballistic test in the same conditions, the final velocities of the bullets showed that how much energy absorbed by the samples. The energy absorption of each sample through the ballistic impact has been calculated, accordingly, the decent ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterize the material properties.

Experimental Study of the Influence of Stacking Order of the Fibrous Layers on Laminated Hybrid Composite Plates Subjected to Compression Loading

ABSTRACT This paper presents an experimental study of the compressive strength and failure mechan... more ABSTRACT This paper presents an experimental study of the compressive strength and failure mechanisms are investigated for hybrid composites. Static uniaxial compressive tests are performed on notched specimens made from two layers of carbon, glass, and Kevlar fibrous and epoxy resin combined to give six different stacking hybrid composite materials. Stacking sequence and orientation of them are as follows; Hybrid 1 : [0K/0C/0G/0K/0G/0C]S , Hybrid 2 : [0G/0C/0K/0C/0K/0G]S , Hybrid 3 : [0K/0G/0C/0G/0C/0K]S, Hybrid 4 : [0G/0K/0C/0C/0G/0K]S , and Hybrid 5 : [0K/0C/0G/0G/0C/0K]S. Cohesive zone model is applied to estimate the compression strength. Moreover stacking the first layer with glass fibre is better than to use the Kevlar fibre, and using the combination of carbon and glass is more efficient than using in the central layers, moreover, using the carbon fibre is not recommended at the last layer.

An Experimental Investigation Of The Effects Of Stacking Sequence On Hybrid Composite Materials Response To Open-Hole Compression Strength

ABSTRACT http://www.crestjournals.com/CREST/issue-9/CREST-MECH-RP-3.pdf

The effects of stacking sequence layers of six layers composite materials in ballistic energy absorption

ABSTRACT In the current paper, the effects of stacking sequence layers of hybrid composite materi... more ABSTRACT In the current paper, the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption, which were fabricated from two layers of each Kevlar, carbon, glass fibres and resin have been experimentally investigated at the high velocity ballistic impact conditions. All the samples have got equal mass, shape and density, but they have got different stacking sequence layers. After running the ballistic test in the same conditions, the final velocities of thebullets illustrated that the amount of ballistic energy absorbed by the samples. The energy absorption of each sample through the ballistic impact has been calculated, accordingly, the decent ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties, and especially the effect of stacking sequence.

Experimental Validation on Time Base Analysis of Various Aircraft CFRP Panel Conditions for Structural Health Monitoring

Key Engineering Materials, 2013

This paper evaluates the feasibility and effectiveness, within controlled conditions of an active... more This paper evaluates the feasibility and effectiveness, within controlled conditions of an active pitch catch sensing PZT sensors on two panels and an aircraft structure made from carbon fiber reinforced plastic (CFRP) pre-impregnated materials. Once cured, the exhibits were subjected to partial and full penetration damages. Two PZT sensors each acting as an actuator and receiver were placed across the investigated region at 100mm apart. Three conditions were set on each panel for each undamaged, damaged and repaired area. Fifty readings were carried out on each panel for each condition. Feature extraction of the wavelet propagations were applied for the post processing from the captured Lamb wave data. The aircraft structure was also used to acquire data with the same above condition. A promising result shows that the interrogation of the actuating PZT sensors can differentiate the studied condition for both panels and structure. In addition, distinguished wavelet patterns were con...

Key Engineering Materials, 2011

The improvements of buckling and post-buckling behaviours of laminated composite plates were done... more The improvements of buckling and post-buckling behaviours of laminated composite plates were done by changing the composite related parameters such as the level of anisotropy, thickness to width ratio and boundary condition. In recent years, shape memory alloy has been used to achieve such improvements. A study is conducted on the buckling and post-buckling improvements of composite plates due to the combined effects of composite and shape memory alloy related parameters. Shape memory alloy wires are embedded within laminated composite plates and the amount of recovery stress induced by the shape memory wires is predicted using the Brinson’s model. A geometric non-linear finite element method is used to model the buckling and post-buckling behaviours of shape memory alloy composite plates and source codes are developed to solve the model. It is found that significant improvements in buckling and post-buckling behaviours of composite plates can be attained by combining the effect of ...

Advanced Materials Research, 2011

Shape memory alloy was firstly used commercially as a hydraulic coupling in the Grumman F14A in 1... more Shape memory alloy was firstly used commercially as a hydraulic coupling in the Grumman F14A in 1971. It is today used among others to improve structural behaviours such as buckling of composite plates in the aerospace vehicles. In this paper, finite element model and its source code for thermal post-buckling of shape memory alloy laminated composite plates is presented. The shape memory alloy wires induced stress that improved the strain energy, stiffness and thus the buckling behaviour of the composite plates. The finite element formulation catered the combined properties of the composite and shape memory alloys, the addition of the recovery stress and the temperature dependent properties of the shape memory alloys and the composite matrix. This study showed that by embedding shape memory alloy within layers of composite plates, post-buckling behaviours of composite plates can be improved substantially.