Materials Engineering Symposium on Innovation for Industry

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item: Conference-Abstract
Characterization of creep behaviour of viscoelastic materials by ultrasound pulse- echo technique
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) HEWESSAGE, HDDN; KOTHALAWALA, SSW; Sivahar, V; Abeygunawardana, AAGA
For any viscoelastic material, creep is a phenomenon which tends to change microstructure and the mechanical properties of material. Therefore, it is important to quantify and predict the creep and creep rate of a component. In this investigation, several samples of LDPE were used to measure the creep and both ultrasonic attenuation and velocity measurements using a 5 MHz transducer were employed for characterizing the samples. Our findings indicate that velocity and attenuation measurements can be used to characterize and quantify creep and creep rate of viscoelastic materials.
item: Conference-Abstract
Design and fabrication of split Hopkinson pressure bar apparatus to investigate high strain rate mechanical behavior of low carbon steel
(Department of materials Science and Engineering, University of Moratuwa., 2021-12) Edirisinghe, DJ; Nidushan, ND; Abeygunawardana, AAGA; Abeygunawardana, AAGA
This work consists of designing and fabricating of compression split Hopkinson pressure bar (SHPB) apparatus to investigate the high strain rate stress-strain behavior of low carbon steel at strain rates of 217.686 s-1, 283.728 s-1, and 356.692 s-1. High strain rate mechanical behavior at the aforementioned regime has never been studied in Sri Lanka; notably with SHPB apparatus. High strain rate behavior of materials is essential in designing mechanical components to be used in high loading impact components such as sports equipment, automotive applications and ballistic applications. General mechanical behavior analogies used for quasi static regime such as universal tensile testing machine are inaccurate and inadequate in dealing with high strain rate related studies. A test bench, loading device, an incident bar, a transmission bar, bar holders, a momentum trap, and standard specimens were fabricated. Two data acquisition and recording systems were used for collecting data from the incident bar and the transmission bar with a maximum sampling rate of 428571 Hz. The data acquisition and recording system components were strain gauges, a Wheatstone bridge circuit, an amplifier, a microcontroller, a power supply, a USB hub, and a USB to micro-B cable and computer. Software codes were developed to collect the data and process the experimental data and determine the corresponding flow curves. In further work on this area, it was recognized to use much more accurate strain gauges suitable for the high strain rate applications so that the data will be more accurate and efficient.
item: Conference-Abstract
Design and optimization of linear actuator for biomedical applications
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Chandrasiri, WAD; Rashmika, WAD; Adikary, SU; Abeygunawardana, AAGA
Microelectromechanical system (MEMS) actuators are a promising innovation that is essential to the development of a wide variety of biomedical devices. The invention of smaller fluid pumps has been valued with increasing interest, these miniaturized micro pumps are designed to handle a very small, precise, and controllable amount of fluid normally in the range of μl/min to ml/min. Thyroid hormone imbalance is a highly increasing, common, genetically or non-genetically disease, which is conducted to Hypothyroidism (an underactive thyroid gland) and Myxedema Coma. So, levothyroxine should be injected frequently into the human body to maintain the metabolic system. This research was carried out to design a linear actuator for a micro pump that injects a certain dose of levothyroxine hormone into the human body accurately. Lead Zirconate Titanate (PZT) gives a high piezoelectric charge coefficient value with high frequency and stiffness that is required for the micro pump. Theoretical mathematical calculations of the piezoelectric stack configuration were carried out to get the displacement of the actuator and maximum displacement. Considering water as the fluid, an equation for flow rate was derived theoretically with supposing fluid behave as a laminar flow. Finite Element Analysis (FEA) was performed to identify the suitable dimensions of the micro pump which is compatible with the flow rate of the fluid.
item: Conference-Abstract
Design of natural fiber and wastepaper composite using numerical analysis method
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Madushani, RK; Dilhari, BA; Udayakumara, SV; Abeygunawardana, AAGA
The consumption of papers in various applications has been increased rapidly during the past decades. To produce one ton of paper; 12 trees, 540 000 liters of water, fuel consumption for transporting the trees are used whereas 10 liters of water is needed to make one A4 paper. Thus, during paper production natural resources are enormously utilized as well as many chemicals are involved in the process. Therefore, this study was conducted to design a wastepaper-based composite with natural fiber as reinforcement. Jute, coir, silk, and wool fibers selected as reinforcement and the study was carried out using simulation in SOLIDWORKS software. Among the selected fibers jute fibers showed better properties and therefore it was selected for composites simulations. Firstly, volume fraction was calculated, and the critical volume fraction was determined. Critical fiber volume fraction was nearly 0.23. Then the fiber volume fraction was optimized using COMSOL Multiphysics software. The periodicity boundary condition and rule of mixture techniques were used to compare and obtained the most suitable fiber volume fraction. The optimized fiber volume fraction was 0.4. Thereafter the micromechanics analysis of a unit cell was carried out with the most suitable fiber volume fraction. The elasticity matrix was obtained for the material. Finally, the stress analysis of the composite was done by applying a 100N load on the composite, which was fixed from four edges. The longitudinal elastic modulus obtained was 8.0726GPa with a thickness of 0.4mm and a Grammage of 488.92 gm-2. Thus, a natural fiber composite with wastepaper can be produced with most suitable fiber volume fraction of 0.4 with numerical analysis methods.
item: Conference-Abstract
Design/fabrication of bi-axial tensile testing machine and numerical modeling of polymer composite under bi-axial stress state
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Arachchi, KADDK; Sandanayaka, SMP; Abeygunawardane, AAGA; Weragoda, VSC; Abeygunawardana, AAGA
In real engineering applications, materials are subjected to different types of loads applied in several directions. Characterizing materials using the Uni-axial tensile testing can be only enough for Isotropic materials. But it is not accurate when testing the Anisotropic materials where the properties vary with different crystallographic orientations. The main scope of this research is to Design & Fabricate the Sri Lankan first ever Bi-Axial Tensile Testing Machine to Characterize Polymer Composites. This study enabled to fabricate a full-scale Bi-Axial Tensile Testing machine for the first time in Sri Lanka. The machine uses four linear actuators which allow cruciform specimen subjected to load from two independent directions. A non contact strain measurement technique using digital Image correlation has been used to measure the strain induced in the specimen. MCalibration – an optimization numerical tool was used to calibrate the best fit material model for the particular application under the biaxial stress state, and a commercial FEA software ABAQUS was used to build and analyze the tested material for its anisotropic nature.
item: Conference-Abstract
Designing an elastomer for reinforced elastomeric cushion bridge expansion joints
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Welivita, WKCS; Wijayasiri, ISWC; Weragoda, VSC; Abeygunawardana, AAGA
This project is focused to improve the properties and to avoid the premature failures of the Reinforced Elastomeric Cushion Bridge Expansion Joint which is used by the industrial organization of Expressway Operation, Maintenance and Management Division of Road Development Authority in Sri Lanka. During the project, COMSOL Multiphysics software was used to analyze the stresses of the expansion joint. Rubber compounds were mixed in a two-roll mill according to a predetermined formulation and were vulcanized using a compression molding machine. Tensile strength, hardness, abrasion resistance, aging resistance (ozone aging and hot air oven aging) were measured according to the standards.
item: Conference-Abstract
Designing of rubber based strain sensor as a vehicle tyre performance indicator
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Vinoshan, S; Kobika, B; Weragoda, VSC; Abeygunawardana, AAGA
For the development of strain sensor to measure the uneven deformation in the vehicle tyres, so that to improve the safety of the vehicles and self- driving cars. the design of elastomeric strain sensor fulfils the requirement of tyre properties change during application. Rubber strain sensor works like piezoresistive material because electric properties change while change the strain of the subject. Therefore, elastomeric strain sensor composition with rubber composites based on natural rubber and electric conductive filler such as carbon black and carbon nanotube have been studied and used for work like as piezoresistive. Develop the strain sensor as its performance does not lose while dynamic load application. The carbon black filler network composition changes during applied load. The rearrangement of the filler network happens while realizing the load. Considering crosslink density and stiffness that affect the performance of sensor composition was selected because lower crosslink density make mobility of filler network so is improve the electric properties. Suggestion on develop a circuit for detect the senor resistance variation and mount in the vehicle tyre was done. The analysis data transfer to the vehicle electronic system for identify what are issues such as road condition, improper tyre pressure, tyre vibration level and steering angle. Then according to the information vehicles can make warning to the diver and make safety improvement.
item: Conference-Abstract
Determine the relationship between corrosion rate and grain size of low carbon steel
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Sivasangaranathan, V; Sirinatha, DR; Sivahar, V; Abeygunawardana, AAGA
There are few studies on the effect of grain size on the corrosion rate of low carbon steel. In the current work, a series of grain sizes have been obtained in typical low-carbon steels through simple heat treatment. As we all know, grain refinement can improve strength and wear resistance. The inherent processing involved in grain refinement will change the volume and surface area of the material, resulting in changes in grain boundary density, orientation and residual stress. Ultimately, these surface changes will have an impact on the electrochemical behavior, thereby affecting the corrosion sensitivity. A large number of studies on the effect of grain size on corrosion have proved this, covering a variety of materials and test environments. However, the basic understanding of how grain refinement affects the corrosion resistance of steel, and more generally, how grain size affects the corrosion rate of low carbon steel, is very limited. The existing literature is often contradictory, even within the same steel category, and to a large extent lacks a consistent understanding of how grain size affects corrosion response. It is necessary to consider whether or how changes in grain size affect the behavior of specific steel in a specific environment.
item: Conference-Abstract
Development of a theoretical model to predict filtration efficiency of electret based masks
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Wimalasinghe, BP; Siriwardhana, BM; Attygalle, D; Abeygunawardana, AAGA
In this study, a 2-Dimensional computational model to predict the filtration efficiency of the electret layer of N95 facemask was developed. The fiber packing density, fiber diameter and fiber layer thickness were included as the parameters defining the fiber structure for the model. Random 2-Dimensional fiber structure were designed using MATLAB and AUTOCAD software while COMSOL Multiphysics was used to simulate filtration mechanisms. The developed model was used to study the filtration mechanisms behavior with various surface charge densities and fiber packing densities. Also, the effect of sticking probabilities with the electrostatic and mechanical filtration were observed.
item: Conference-Abstract
Development of cellulose fiber reinforced soil-based composite wall panels using selected lignocellulosis materials
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Jayaweera, WMIS; Malshan, MMH; De Silva, GIP; Fernando, TN; Abeygunawardana, AAGA
The present study focuses on preparation of composite wall panels, reinforcing with three different pre-treated lignocellulosic material fibers - bagasse (B), paddy straw (PS), and banana stem (BS). Soil-based composite wall panels were prepared by mixing cement, laterite soil, and lignocellulosic materials in the weight ratios of 1: 1: 0.025. Morphological characteristics, water absorption, flexural strength, and thermal conductivity were tested in prepared wall panels after keeping at curing period of 28 days. The characterization results of molded wall panels indicate the variation of flexural strength as 1.85 - 4.05 MPa, percentage of water absorption as 14.7-20.2% and thermal conductivity as 0.131 -0.252 W/mk. The characteristics of some molded wall panels prepared in the present study were at a satisfactory level compared to the market available wall panels.
item: Conference-Abstract
Development of cellulose-based precursor solution for electrospinning technique
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Basnayaka, BMCGK; Udeshini, AA; Samarasekara, AMPB; Amarasinghe, DAS; Abeygunawardana, AAGA
To electro-spin a polymer solution, certain specific conditions need to be met, for example, acetyl content (A) (38- 40%), degree of substitution (DS) (2.3-2.5), molecular weight(M) (30,000 100,000 gmol-1) solution system of CA 15w%, acetone 80w% and water 5w%. This study aimed to produce an electro-spinnable cellulose acetate precursor solution from raw cotton. This paper discusses the cellulose extraction process as well as the characterization process. The electro-spun cellulose acetate fibers are significantly crucial to high-tech product designs.
item: Conference-Abstract
Development of cement, waste paper, and natural fiber based composite for ceiling sheet
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Kumarasinghe, PDRS; Sachintha, KKN; Udayakumara, SV; Abeygunawardana, AAGA
This study was focused on developing material for ceiling sheets using waste paper and cement. Every day, a large amount of paper waste is discarded into the environment. The new ceiling composite is produced, which is low-cost, lightweight, and non-hazardous while contributing to waste management. Coir fiber is used as reinforcement in the composite. Samples were prepared by adding 0.5%, 1%, 1.5%, and 2% of coir fibers to the total weight of the samples. The ratio between waste paper pulp and cement was kept at 1:1. Flexural strength, water absorption, thermal conductivity, and density of the samples were measured after 28 days of hardening. The optimum fiber percentage was identified by analyzing the results. After identifying the optimum fiber percentage, the percentage variation of flexural strength was studied with the fiber length. Variation was studied for the 1, 1.5, 2, 2.25, 3, and 3.5-inch fiber lengths. A cost analysis and comparison of the properties with the commercially available ceiling sheets were done.
item: Conference-Abstract
Development of soil based composite wall panel using locally available laterite soils
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Samarasinghe, MMA; Gunathunga, WPS; De Silva, GIP; Fernando, TN; Abeygunawardana, AAGA
This research focus on developing laterite soil-based composite wall panels by using soil cement mixture, reinforced with cellulose fibers from pretreated cornhusk. In this, effect of various laterite soils and cement proportions of the mixture on the properties of wall panels like flexural strength, water absorption and thermal conductivity were determined. It has been observed high Al2O3+Fe2O3 content, good particle size distribution, lower clay content of soil shows good performance of wall panel properties. Further, lowering the cement content of the mixture reduces the wall panel performance.
item: Conference-Abstract
Dying of cotton fabric with a natural dye extracted from Areca concinna peel
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Ranathunga, RGSM; Wanigasekara, KV; Udayakumara, SV; Abeygunawardana, AAGA
In modern world, most of the countries tend to use the eco-friendly concept in many industries to minimize environmental pollution. Synthetic dyes that are used in the textile industry offer more unfavorable and harmful effect to human beings such as carcinogenic, health-hazardous like skin allergies, etc. Also, there is no systematic way to dispose of synthetic waste to the environment. So that it can be harmful to the ecosystem. Therefore, the world tends to use natural dyes instead of synthetic dyes. Natural dyes have many advantages than synthetic dyes such as noncarcinogenic, eco-friendly, non-allergic, non-hazardous to human beings, etc. Natural dyes are mainly extracted from three different sources such as minerals, plants, and insects. Among these, plants are the most abundantly used natural dye source to extract dyes. The main objective of this study was to extract natural dye from For Lane areca peel (Areca concinna) peels and use extracted dye to dyeing the cotton fabrics. This is not a common natural dyestuff. It was an effort to utilize the waste material in an efficient manner which could minimize the cost of dyeing. The natural dyestuff solution obtained was applied to cotton fibers treated with 4% tannic acid. Dye absorption for fibers accompanied by a pre, simultaneous and post mordanting methods with the chemical mordants as chrome, copper sulfate, ferrous sulfate, and stannous chloride. Fastness properties of the dyed fabric were investigated including wash fastness test, perspiration test and crock fastness. These tests were helped to confirm whether the extracted dye can be used for commercial purposes. Various hues of colors were obtained from mordanted cotton and wool make significant changes in K/S values, changes in L*, a*, b* values, and brightness index value. The color strength of dyed fabric can be assessed by using a UV-visible spectrophotometer.
item: Conference-Abstract
Effect of annealing on temperature coefficient of resistance of cu-ni foil strain gauge
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Satheekshana, KKW; Weragoda, VSC; Abeygunawardana, AAGA
Near zero Temperature Coefficient of Resistance (TCR) is an increasing concern in strain gauge manufacturing industry. The purpose of this study is to investigate the connection between TCR of strain gauge and annealing temperature of the foil which used in manufacturing of the gauge. Under non oxidizing annealing environment, Constantan foils were heat treated and TCR of the strain gauges were calculated in the range of -10°C to 40°C. The TCR values were shifted from negative to positive with annealing temperature. This study definitively answers the question regarding selection of annealing temperature of Constantan foil for the manufacturing of strain gauges with near zero TCR.
item: Conference-Abstract
Electric double layer capacitors (EDLC)
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Amarathunga, S; Malshan, LJP; Amarasinghe, DAS; Abeygunawardana, AAGA
A capacitor is an energy storage device that generates an electric field between electrodes and builds potential that can be channeled through associated circuits. The Electrical Double Layer (EDL) capacitor is a unique capacitor with a remarkably higher capacity. The energy densities of these capacitors can range between 0.5 and 10 Wh/kg. These values are still lower than the energy densities of mainline batteries. However, they fill the gap between the rechargeable batteries and the electrolytic capacitors. EDL-based supercapacitors were initially used as starter devices for the tank and railroad engines. Nevertheless, they are currently found in appliances and handheld devices. There is a growing market for the product in the transportation industry. Many automotive companies use doublelayer capacitors to shield certain electrical engine parts from voltage fluctuations. Under this study, the dependence of the EDL capacitance on the surface roughness profile of the electrode was investigated using the linear Poisson-Boltzmann theory and the Gouy-Chapman theory. A 1-D model was developed based on first principles to examine the effects of surface roughness. The model developed is important in selecting materials for electrode design.
item: Conference-Abstract
Electrode – electrolyte interface analysis by molecular dynamics simulation
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Virajini, RLAC; Sitinamaluwa, HS; Abeygunawardana, AAGA
The research for renewable energy generation methods requires the development of novel, sustainable energy storage methods. Supercapacitors are much promising for future energy storage applications, owing to their high energy density and rapid charge-discharge time. supercapacitors are widely used in the following ways: firstly, the largest proportion of commercial supercapacitors are used in consumer electronics, in which they mainly serve as backup sources for memories, system boards, clocks and microcomputers; secondly, supercapacitors are used as the main power source, such as fail-safe positioning devices and starter applications. The performance of supercapacitors can be improved by using high surface area electrode materials, which could increase the energy density of the device. In this regard, nanomaterials are much advantageous owing to their high surface to volume ratio. In this study, graphene and titanium dioxide nanotube arrays are studied as a supercapacitor electrode material, using molecular dynamic simulation. This study focuses on mathematical modeling of electrode-electrolyte interface, to study the charge storage mechanism of the electrode when in contact with the electrolyte. Firstly, the molecular dynamic simulation (MD simulation) method was used to study graphene-electrolyte system using a planar electrode model. There, the formation of electric double layer with different charge levels are studied. secondly, molecular dynamics simulations have been conducted to study the interaction between anatase TiO2 (100) surface and water. The effect of surface orientation of the TiO2 surface on the interface properties was studied.
item: Conference-Abstract
Evaluation of performance of modified graphene based materials in latex films
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Dilina, JMA; Gamage, GGUV; Liyanage, NMVK; Abeygunawardana, AAGA
Natural rubber (NR) is one of the main natural materials used in various industrial applications. In order to tailor the natural rubber material according to the end application, natural rubber latex compounding is done, introducing various additives. Fillers are one of the major categories of additive in a latex compound which reduces the cost while catering the final performance of the product. In latex film manufacturing the widely used filler Silica (SiO2) is an inorganic compound which consists of hydroxyls on its surface which impart poor dispersion properties in an organic matrix such as rubber. Surface hydroxyl groups lead to agglomeration of silica particles which directly affects the mechanical properties of NRL thin film products. This issue has been discussed in both academic and industry environments; thus, many studies have introduced different coupling agents such as silane, alkanol amide, polydiallyl dimethylammonium chloride (PDDA) etc. Natural rubber composites filled with Silica, graphite and its derivatives, and modified silica with various forms of graphite have been studied. This research is aimed to improve of filler rubber interaction of silica filled NRL thin films in the presence of exfoliated graphite. Here, Graphite was exfoliated by using a ball milling method assisted with a Naphthalene sulphonic acid derivative (i.e. Tamol) and was used to improve the aqueous dispersion of silica to improve fillerrubber interaction through inter molecular attraction. Optical microscopy, SEM analysis and Raman spectroscopy were used to characterize exfoliated graphite. Properties of vulcanizates were characterized by tensile strength test, tear strength test, swelling test, and SEM analysis. Overall results show that introduction of exfoliated graphite into silica dispersion has enhanced its properties imparting some improvements in physical properties of NRL thin films.
item: Conference-Abstract
Evaluation of performance of modified graphene based materials in tire tread formulations
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Kumarasiri, PGA; Madhusanka, JDI; Liyanage, NMVK; Abeygunawardana, AAGA
Tire tread is the outer part of the tire that contacts the road or the ground. To improve its performance, effectiveness of different types of additives has been studied in various researches. Graphene which is considered as the basic structural element of carbon allotropes shows unique properties like excellent thermal conductivity, high strength, and relatively lower density. Therefore, it can be used as an additive in tire tread formulations because enhancing mechanical and thermal properties of tire is an important factor in modern tire industry. In this research, the possibility of synthesizing graphene and/or exfoliated graphite from a ball milling technique has been studied. Also, the properties of the composites of Natural rubber and Exfoliated graphite have been studied. This research is aimed to improve mechanical and thermal properties of tire treads using modified graphene-based materials. Optical microscopy, SEM analysis and Raman spectroscopy were used to characterize exfoliated graphite. Rubber compounds were mixed in a two-roll mill according to a predetermined formulation and were vulcanized using a compression molding machine. Rheological properties of the compounds were characterized by Moving Die Rheography and physical and thermal properties of vulcanizates were obtained using tensile test and Lee’s disk method respectively. Final results show that the exfoliated graphite has enhanced the thermal conductivity and physical properties of tire tread compounds.
item: Conference-Abstract
Investigation of electrical properties of microcrystalline cellulose based composite materials
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Lingeratnam, V; Lavanya, N; Samarasekara, AMPB; Abeygunawardana, AAGA
Polypropylene - micro crystalline cellulose-based composites have shown great potential in various applications as a modern composite material. Microcrystalline cellulose has gained great interest in composite fabrication as a reinforcing material, with the advantages of higher physical and mechanical properties, which comes with its peculiar micrometric dimensions. In this study, microcrystalline cellulose was incorporated into polypropylene based composites to improve the electrical properties of Polypropylene based polymer composites. Hydrophilic Microcrystalline cellulose creates a weak interface with hydrophobic polypropylene resulting poor compatibility in two materials. Therefore, sunflower oil ethyl esters were used as the surface modifier to improve the compatibility with hydrophobic polypropylene. Sunflower oil ethyl esters were trans esterified onto microcrystalline cellulose surface using ultrasonication technology to enhance the surface hydrophobicity of microcrystalline cellulose. Modified microcrystalline cellulose was characterized by FTIR, SEM and wettability analysis. The electrical properties such as dielectric loss, dielectric constant and AC electrical conductivity of the developed composites were experimentally determined in this study. Experimental results indicated that the variation of dielectric constant and dielectric loss characteristics values of Polypropylene-microcrystalline cellulose composites at different microcrystalline cellulose loadings over the frequency range of 50 Hz – 5MHz.