MESII - 2021

Permanent URI for this collectionhttp://192.248.9.226/handle/123/17184

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item: Conference-Abstract
Materials Engineering Symposium on Innovations for Industry 2021 (Pre Text)
(Department of materials Science and Engineering, University of Moratuwa., 2021) Abeygunawardana, AAGA
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 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
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
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
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 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.
item: Conference-Abstract
Investigation of thermo-mechanical behavior in polymer based mallet compound with graphite
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Gunawardhane, HMD; Abhysinghe, IMS; Abeygunawardane, AAGA; Abeygunawardana, AAGA
This research is based on the mixing of vein graphite powder with rubber compound; which is used to produce polymer-based mallets. Based on the records from the industry, normally these mallets have a higher curing time. So, this research aimed in reducing cure time by improving the thermal properties in the compound. The compound was mixed with vein graphite powder at different weight ratios and investigate the mechanical and thermal behavior. The graphite powder was used as a filler and was mixed with rubber compound at 2.5%, 5%, 7.5% and 10%. Under the mechanical properties in the samples, the tensile strength, resiliency, specific gravity, ML and MH were done and checked and analyzed their results. This work includes the behavior of mechanical properties of the compound with increasing graphite percentage up to 10%. Also, thermal conductivity, thermal diffusivity, specific heat capacity, TS2 and TC90 in the samples were investigated under the thermal properties of that sample compounds. Thermal conductivity of the compound was increased and TC90 was the same as the normal sample. Other properties were nearly the same as the normal sample. Hence the curing time of the mallet can be reduced using this modified compound.
item: Conference-Abstract
Measurement of steady state thermal conductivity of rubber compounds
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Dushyantha, AAN; Pathiraja, PACP; Weragoda, VSC; Abeygunawardana, AAGA
This Project is based on the Measurement of Steady-State Thermal Conductivity by Lee’s Disc method. The main purpose is to facilitate measuring the thermal conductivity by minimizing the inherent errors of the original process. Thermal conductivity is the ability of a material to conduct heat, and it represents the quantity of thermal energy that flows per unit time through a unit area with a temperature gradient of 1°per unit distance. Thermal conductivity is a necessary feature to dissipate the transformed thermal energy in a system. Thermal conductivity is a fairly very important material property for processing of rubber during part manufacturing because temperature distribution affects degree of crosslinking and hence maintaining the properties of the end part correctly. The thermal conductivity of a rubber compound ideally needs to be studied as a function of its state of curing and temperature. However, the device is presented at this stage is a steady state instrument which is capable of measuring the thermal conductivity of a compound at any temperature within the range 40°C to 180°C. The instrument uses an electric heat source which transfers a steady quantity of heat through the test specimen which heats up a metallic mass to a steady temperature. The power generated at the steady state of the system is balanced by the power dissipated directly from the source and the power dissipated through the test specimen to the heat sink. The steady state temperatures are used to calculate the thermal conductivity of the material.
item: Conference-Abstract
Modeling of laser assisted thermal reduction of graphene oxide for the development of a strain gauge
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Wamakulasooriya, WMDS; Rajapakshe, VS; Attygalle, D; Abeygunawardana, AAGA
A computational model to predict the degree of reduction of graphene oxide by using laser irradiation was developed. 3-Dimensional thermal distribution was modeled using heat conduction equation and computational modeling was done using COMSOL Multiphysics software package. Mathematical model for reaction kinetics was carried out considering Lerf and Klinowski model of graphene oxide and thermal profile of graphene oxide, which predicts the oxygen percentage distribution along the surface and depth after laser irradiation. Combinations of laser wavelength and laser powers were identified that are feasible for reducing graphene oxide. Conductivity range according to final weight percentage was identified. The work is carried out to model manufacturing process of graphene-based strain gauge using graphite and other resources in Sri Lanka.
item: Conference-Abstract
Modelling the mechanical behavior of microcrystalline cellulose- based polymer composites
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Amutheesan, J; Sukirtha, S; Samarasekara, AMPB; Abeygunawardana, AAGA
There is an increasing demand of environment friendly natural polymer reinforced polymer composites in the industrial sector today. The Sri Lankan agricultural industry is one of the areas which generate great amounts of plant-based waste. From these unnecessary agricultural wastes, microcrystalline cellulose can be extracted easily as a value-added product with variety of advantages. Microcrystalline cellulose has been used in wide variety of applications as a reinforcing filler material in the polymer composite. Polypropylene is a widely used useful polymer for polymer composite manufacturing due to its low production cost, recyclability, transparency, ability to mix easily and low density. This research mainly focused on the development of a model to predict the mechanical behavior of polypropylene - microcrystalline cellulose-based composites. Main disadvantage of polymer composite fabrication is extreme hydrophilicity of microcrystalline cellulose and hydrophobicity of Polypropylene. That results weak compatibility and poor performance in the composite. Therefore, surface modification is vital to decrease the hydrophilicity of microcrystalline cellulose and thereby to improve the compatibility and overall performance of the polypropylene-based composite. Sunflower oil ethyl esters were used to modify the microcrystalline cellulose surface in order to improve cellulose surface hydrophobicity. Surface modified microcrystalline cellulose was characterized by using FTIR analysis, SEM analysis, and Wettability test. Polypropylene was blended with different loadings (0, 1, 2, 3, 4 and 5%) of microcrystalline cellulose to study the property variation with microcrystalline cellulose loading. Tensile, hardness, and impact properties were measured experimentally for the fabricated composite. Meanwhile, mathematical models were developed by using theoretical approach to evaluate the mechanical properties. Developed mathematical models indicated the corelated mechanical properties with experimental values.
item: Conference-Abstract
Modelling and validation of nano hydroxyapatite formation for medical applications
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Dhananjaya, GS; Madushanka, D; Adikari, SU; Abeygunawardana, AAGA
In this study, a wet chemical synthesis of Nano-hydroxyapatite HAP [Ca10(PO4)6(OH)2] was investigated through a kinetic model derived based on the classical nucleation theory. The model mapped the nucleation rate from synthesis variables, supersaturation, temperature, and interfacial tension. During the study, the effect of supersaturation for nano formation of hydroxyapatite particles was experimentally studied keeping the other two variables constant. Since a direct measurement is not possible to measure the nucleation rate, the induction time, which is inversely proportional to the nucleation rate, was introduced to the model. The model simply suggests that the induction time will decrease with increased supersaturation. Also, it indirectly predicted the finer particles for lower induction times caused by higher supersaturations. Then the model was subjected to the validated process with a proper experimental design. During the experiment, the nano-hydroxyapatite powder was synthesized using Ca(OH)2 and H3PO4 as precursors at five different supersaturations while the temperature for the whole study remained the same as 300C. The supersaturation for hydroxyapatite was caused by changing the concentration of precursors maintaining the constrained Ca/P molar ratio near 1.6-1.7 between Calcium and Phosphorus. The H3PO4 was added to the Ca(OH)2 suspension at a constant acid addition rate of 4 ml/min using a burette under vigorous stirring having maintained the final pH at 10. During the synthesis reaction, the variation of pH of the mixed precursor suspension was measured and analyzed. The main parameter obtained from the experiment was the induction time. This induction time was marked by the onset of the first and more significant pH drop in the final mixture. After 48 hrs. of aging, the precipitate was separated by centrifuging at room temperature. Then the resulting wet powder samples were dried and characterized. First, the predicted model validity was investigated through a linear regression model and the regression/ kinetic constants were determined. In statistical validation, 95.84% variability could be described by the predicted model according to R2-test. In addition, the validated model could be applied to describe the nucleation process with the critical radius approach for each sample. With laser particle analyzer results, it was obvious that there was a significant reduction in the particle size when the supersaturation was higher. The model predicted this was caused by the higher nucleation density with increased supersaturation. In that scenario, the nucleation mechanism would be dominant compared to the growth of hydroxyapatite. The morphological and chemical analysis with SEM revealed that the formation of hydroxyapatite in solution is not a single-step process and it takes place via some amorphous intermediates with a time-dependent Ca/P molar ratio. In nano-sized form, hydroxyapatite is extensively used for a variety of extended medical applications. Finally, this model was experimentally validated by Laser Particle Analyzer and SEM studies. FTIR studies showed the characteristic peaks in hydroxyapatite and a trace amount of carbonate incorporation was observed in the lattice due to the synthesis in atmospheric conditions.
item: Conference-Abstract
Modelling of micro size ultrasonic generator and receiver characteristics of lead zirconate titanate and polyvinylidene fluoride using finite element analysis
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Thasankithan, VS; Gamage, UV; Adikary, SU; Abeygunawardana, AAGA
Ultrasonic devices (sensors, generators and transducers) using piezoelectric materials are more prominent due to its accuracy, efficiency and ease handling. In this research, modelling and simulation of ultrasonic generator and receiver characteristics were performed using finite element analysis (FEA). PZT is the most popular piezoelectric ceramic in ultrasonic applications due to its higher coupling factors, which is the main reason why PZT-5H was chosen for FEA analysis over other piezoceramic materials. PVDF was chosen for FEA analysis over other piezopolymer materials, due to its high piezoelectric voltage coefficient. Then piezoelectric constitutive equations for direct effect and indirect were used for mathematical calculation in thickness mode to determine the generated voltage and displacement along the z direction. The dimensions of the design were selected in micro scale. Using the FEA simulation, disc shape ultrasonic generator and receiver were designed. To identify the resonant frequency of the model wizard, 3D model was created using COMSOL Multiphysics software. The FEA simulation was implemented via 4 different cases, for instance using PZT-5H as generator material with PVDF and PZT-5H as two separate ultrasonic receiver materials and PVDF as generator material with PVDF and PZT-5H as two separate ultrasonic receiver materials. Initially the resonant frequency of the piezoelectric disc was determined as 13 MHz from the simulation and electric potential of 10V with 13MHz was used to generate the ultrasound wave. This ultrasonic wave was then directed to hit the ultrasonic receiver to generate electric potential. When PVDF worked as receiver it generated higher electric potential than PZT. On the other hand, when PZT worked as an ultrasonic generator the high amount of ultrasonic pressure was generated.
item: Conference-Abstract
Quality control of manufactured tires through nondestructive test
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Priyanthini, B; Sivahar, V; Abeygunawardana, AAGA
The industries are getting better and better with the evolution of technology. Every product which is manufactured need to be quality checked to ensure the quality of the product to the customer. Different types of testing methods are introduced into the market to ensure the quality of products. The testing techniques can be categorized into two types as nondestructive testing techniques and destructive testing techniques. With the advancement of technology various kinds of nondestructive testing techniques are getting popular now a days because these testing methods does not do any damage to the testing products. Tire manufacturing is one of the biggest industries in the globe. Different tire manufactures promote their quality of products through various testing process. But tire industries face a huge issue on testing of tires since their testing techniques are mostly destructive which causes extra cost in their production. This research project worked on identifying a proper industrially viable Non-Destructive testing method for quality control of tire.
item: Conference-Abstract
Simulation and analysis of effect of halide lons of perovskite-on- perovskite solar cells performance
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Ranasinghe, S; Kuruppu, HYL; Galhenage, AS; Abeygunawardana, AAGA
Perovskite solar cells (PSCs) have attracted significant interest of scientists as well as industrialist as the latest generation of solar cells due to their sky rocketing performances. In this study, the effect of Halide Ions of perovskite on PSCs performances were studied using solar cell capacitance simulator (SCAPS). Perovskite solar cells with MAPbI3 and PSCs with MAPbBr3 as the lightabsorbing materials have been simulated and compared the effect of the halide ion on solar cell performances. The efficiency of MAPbI3 and MAPbBr3 were reached 16.8% and 5.1% respectively. Also, the thickness of each MAPbI3 and MAPbBr3 was varied from 0.1 μm to 1.2 μm and the best results were observed at 0.5 μm and 0.4 μm thickness of MAPbI3 and MAPbBr3 films, respectively. A considerable effect of halide ions on PSC performances has been observed and it can be attributed to the variation of light absorption with the halide ions.
item: Conference-Abstract
Use of Aruwakkalu sand for medium strength concrete
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Jayarathne, STMP; Rathnayake, RM; Guluwita, SP; Abeygunawardana, AAGA
Cement, sand, and aggregate are the basic needs for any construction industry. Sand is a prime material used for preparation of mortar and concrete. Now a day’s due to the excessive use of sand mining from the rivers for the construction industry river erosion has occurred. Due to this government has implemented several rules and regulations which leads to a shortage of river sand. Due to this cost of river sand has increased. The non-availability and the high cost of river sand will affect the construction industry, hence there is a need to find the new alternative material to replace the river sand, such that excess river erosion and harm to environment is prevented. Many researchers are finding different materials to replace the river sand and one of the major materials found was quarry stone dust. This project is reviewed the suitability of using Aruwakkalu sand, which is a waste product of most of cement industries Limestone quarry in preparation of concrete. Recently natural sand is becoming a very costly material because of its demand in the construction industry. Due to this condition this research aimed for cheap and easily available alternative material to natural sand. Concrete designs were prepared according to BRE mix design. The river sand have been proportionately with Aruwakkalu sand and prepared several designs for grade 25 and casted the cubes. After soaking for 7 days, it was observed that 100% Aruwakkalu sand used Cube shows the highest strength than river sand used concrete designs. Strength wise there is no hesitation of using Aruwakkalu sand. But the salt concentration needs to be considered.
item: Conference-Abstract
Non-destructive evaluation of fruits and vegetables for their maturity and ripening
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Basnayake, BMLC; Madhawa, KDS; Amarasinghe, DAS; Abeygunawardana, AAGA
The state of maturity of a fruit or vegetable is crucial to its subsequent storage and shelf life. Correctly identifying the state of maturity of fruits or vegetables can reduce the post-harvesting loss in the supply chain and lower artificial ripening after the harvest. However, visual inspections are the most widely used method to determine the maturity stage of most fruits and vegetables even today. The visual grading schemes are subjective and thus unreliable. Therefore, more scientific non-destructive methods to define maturity state are needed for ‘high-tech’ horticulture. The life span of harvested fruits or vegetables can be separated into three stages: maturation, ripening, and senescence. Maturation is indicative of the fruit being ready for harvest. The edible part of the fruit or vegetable is fully developed by this time, although it may not be ready for immediate consumption. Though generally, ripening follows the maturation stage, there can be some overlaps between these two stages. Once the product is ripened, it is ready for even immediate consumption, as indicated by taste. Senescence is the last stage. Natural degradation of the fruit or vegetable begins to appear at this stage, as it loses texture, flavor, etc. This study aims to identify the state of maturity of fruits and vegetables by non-destructive tests.

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