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Öğe Adaptive response for climate change challenges for small and vulnerable coastal area (SVCA) countries: Qatar perspective(Elsevier, 2023) Khan, Shoukat Alim; Al Rashid, Ans; Koc, MuammerClimate change has already been affecting the entire globe in all aspects of life. Along with mitigation efforts, adaptive response actions are gaining increasingly urgent importance for many regions to considerably reduce the most severe impacts of climate change on social and physical infrastructure. As the severity and frequency of climate change impacts and consequences grow fast and highly alarming, particularly for small and vulnerable coastal area (SVCA) countries, the urgency and magnitude of the crises call for immediate and more adaptive responses. This study proposes that SVCA countries, being on the frontline of climate change vulnerabilities, impacts, and risks, should prioritize their resources and capacity and focus on developing and implementing immediate, tailored, adaptive response policies, plans, and actions. Long-term mitigation efforts would not help them reduce their current or immediate vulnerability in the short-term, as long as large countries with comparably huge populations, economies, heavy industrial dependences, and extreme consumption levels do not change their courses significantly. Therefore, this study presents a framework of climate change, sustainability, resilience, risk reduction, and adaptive response as a nexus to conceptualize the problem and solutions properly. Such a framework is needed to develop synergies between climate change and immediate adaptive response for such countries. The study analyzes Qatar, a typical SVCA country, assessing its current vulnerabilities & risks and potential physical, social, and economic challenges. Finally, it concludes with a discussion on recommended adaptive responses proposed for Qatar.Öğe Additive manufacturing and mechanical performance of carbon fiber reinforced Polyamide-6 composites(Elsevier, 2022) Al Rashid, Ans; Ikram, Hamid; Koc, MuammerAerospace and automotive industries always quest for materials with higher strength-to-weight ratios, as material usage significantly reduces while designing functional components. The design of laminated structures with different core structures is usually practiced to develop lightweight parts. Additive manufacturing (AM) processes have gained significant attention in these industrial structures, owing to flexibility in the design and fabrication of complex core structures. Therefore, it is essential to manufacture and characterize the lightweight structures fabricated through AM processes for better adaptability in such applications. This study reports the experimental investigations on the effect of infill patterns and infill densities on the mechanical performance of additively manufactured carbon fiber-reinforced polyamide-6 (PA6) composites. Sandwich structures with different core designs (namely, triangular, hexagonal, rectangular) and infill densities (varying 18-62%) were fabricated using the fused filament fabrication (FFF) process. The additively manufactured tensile testing coupons were tested using the universal testing machine. Both infill patterns and infill densities significantly influenced the mechanical behavior of 3D-printed composites. It is concluded that triangular and hexagonal infill patterns performed better at lower infill densities, while rectangular infill patterns provided better mechanical strength and elongation at higher infill densities. However, if material saving is the priority, hexagonal patterns are preferred.Copyright (c) 2022 Elsevier Ltd. All rights reserved.Selection and peer-review under responsibility of the scientific committee of the International Conference on Materials, Mechanics, Mechatronics and Manufacturing.Öğe Buildability analysis on effect of structural design in 3D concrete printing (3DCP): An experimental and numerical study(Elsevier, 2023) Khan, Shoukat Alim; Ilcan, Huseyin; Aminipour, Ehsan; Sahin, Oguzhan; Al Rashid, Ans; Sahmaran, Mustafa; Koc, MuammerThe importance of numerical modeling and simulation approaches increases with increased scale as it allows for early results predictions. This study evaluated the buildability of novel construction and demolition waste (CDW)-based geopolymer materials for 3-dimensional printing (3DP) structures for the built environment. The feasibility of the developed numerical model for 3DP of built environment structures was also evaluated. This study reported the fresh-state properties of geopolymer-based materials, and based on these results, numerical modeling for 3DP of geopolymer material was performed. Three cylindrical structures with diameters of 300 mm, 450 mm, and 600 mm were printed, with the same printing conditions, resulting in buildability of 352.5 mm, 322.5 mm, and 277.5 mm (total height constructed before the collapse), respectively. In the next stage of the study, a comparative analysis was performed to assess the compatibility of numerical models for CDW-based geopolymer materials. In the numerical results, three structures showed early failure prediction from experimental results at 31.91%, 29.10%, and 29.73%, respectively. The geopolymer materials developed were suitable for 3DP, and close agreement in results and repeatability were observed. The numerical model provided a reliable failure prediction for different structures. Hence, the model can be utilized to evaluate the buildability of the structures before the actual 3DP, which can significantly reduce the time and cost of the project.Öğe Design and development of a low-cost 5-DOF robotic arm for lightweight material handling and sorting applications: A case study for small manufacturing industries of Pakistan(Elsevier, 2023) Ali, Zain; Sheikh, Muhammad Fahad; Al Rashid, Ans; Arif, Zia Ullah; Khalid, Muhammad Yasir; Umer, Rehan; Koc, MuammerDue to the ever-increasing demand for higher production rates and the shortage of skilled labor in small in-dustries, material handling and sorting have become extremely tedious and challenging. Industrial automation -led effective material-handling solutions like robotic arms have gained immense importance as they provide an alternative to human involvement, contribute to higher sorting accuracy, and provide enhanced safety. However, the adaptability of these robotic arms in small manufacturing industries in Pakistan is mainly hindered due to their higher costs and concerns with their structural durability. This paper presents the development of a low-cost 5-DOF robotic arm with a designed payload limit of 1 kg and automatically sorts objects fed through a conveyer belt. Catering to the compact sizing, high strength, and lower payload requirements of small industries, aluminum was selected as the material of the robotic arm due to its superior strength-to-weight ratio while being lightweight. Arm geometry was developed using SOLIDWORKS & REG; software, which was further processed in ANSYS & REG; software to perform the static structural analysis of the robotic arm using Finite Element Analysis (FEA). The fine meshing of the robotic arm assembly was done using triangular elements with the total number of elements and total nodes 52134 and 89104, respectively. A single point load was applied on the end effector, and the force was kept downward with an incremental loading of 1 kg starting from 100 g. These FEA simulations show that the robotic arm can hoist considerable weight while maintaining its structural integrity and direc-tionality. The proposed robotic arm is also well-suited for manipulating objects in tight spaces due to its compact size and customizable range of motion, making it an ideal choice for applications that require precise manipu-lation of light loads.Öğe Experimental validation of numerical model for thermomechanical performance of material extrusion additive manufacturing process: Effect of infill design & density(Elsevier, 2023) Al Rashid, Ans; Koc, MuammerThe optimum selection of process parameters, materials, and product design is essential to achieve the desired response of 3D-printed structures, especially in functional components. The current practices of the experimental optimization process require significant resources, which can be limited through numerical modeling and simulation techniques. In this study, a thermomechanical numerical model is used to predict the performance of the additive manufacturing (AM) process, i.e., fused filament fabrication (FFF). 3D printing (3DP) process simulations were performed for tensile testing coupons using carbon fiber-reinforced polyamide-6 (PA6-CF) material. The numerical model predicted the effect of infill patterns and densities on the deflections and dis-tortions during the FFF process. The numerical model predictions were validated via experiments performed under similar conditions. The results conclude that the numerical model can adequately predict the process-induced deflections and distortions during the FFF process. Generally, higher dimensional control was observed for rectangular infill patterns and increased infill density. However, the numerical model overestimates the shrinkage as the stress-relaxation effect is not considered in the numerical model and underestimates the warpages as perfect build plate adhesion is assumed.Öğe Experimental Validation of Numerical Model for Thermomechanical Performance of Material Extrusion Additive Manufacturing Process: Effect of Process Parameters(Mdpi, 2022) Al Rashid, Ans; Koc, MuammerThe material extrusion additive manufacturing (MEAM) process for polymers seems straightforward. However, several controlled and uncontrolled factors affect the 3D printed product quality, e.g., MEAM process parameters, thermomechanical properties of the material, and part design. Therefore, it is crucial to understand these interlinked factors of part geometry, material properties, and 3D printing (3DP) process parameters to optimize 3D printed product quality. The numerical models and simulation tools can predict the thermomechanical performance of the MEAM process under given input parameters (material, design, and process variables) and reduce the research and development costs significantly. However, the numerical models and tools need further exploration and validation of simulation predictions for their adaptability and reliability. Therefore, in this study, numerical simulations were performed to observe the impact of process parameters on the part quality of MEAM 3D printed components. The two crucial process parameters (i.e., extrusion temperature and layer resolution) were varied while keeping the other process parameters, part geometry (tensile testing coupon), and material properties (acrylonitrile butadiene styrene (ABS)) constant. These two process parameters were sequentially optimized for optimum part quality, first by varying the extrusion temperature and secondly by changing the printing resolution using the optimum printing temperature. The 3DP process quality was evaluated in terms of dimensional accuracy, distortions, and residual stresses. Finally, the specimens were 3D printed under similar process conditions to validate the numerical model predictions.Öğe Fused Filament Fabrication Process: A Review of Numerical Simulation Techniques(Mdpi, 2021) Al Rashid, Ans; Koc, MuammerThree-dimensional printing (3DP), also known as additive manufacturing (AM), has rapidly evolved over the past few decades. Researchers around the globe have been putting their efforts into AM processes improvement and materials development. One of the most widely used extrusion-based technology under AM processes is Fused Deposition Modeling (FDM), also known as Fused Filament Fabrication (FFF). Numerical simulation tools are being employed to predict the FFF process complexities and material behavior. These tools allow exploring candidate materials for their potential use in the FFF process and process improvements. The prime objective of this study is to provide a comprehensive review of state-of-the-art scientific achievements in numerical simulations of the FFF process for polymers and their composites. The first section presents an in-depth discussion of the FFF process's physical phenomena and highlights the multi-level complexity. The subsequent section discusses the research efforts, specifically on numerical simulation techniques reported in the literature for simulation of the FFF process. Finally, conclusions are drawn based on the reviewed literature, and future research directions are identified.Öğe Material Extrusion 3D Printing (ME3DP) Process Simulations of Polymeric Porous Scaffolds for Bone Tissue Engineering(Mdpi, 2023) Imran, Ramsha; Al Rashid, Ans; Koc, MuammerBone tissue engineering (BTE) is an active area of research for bone defect treatment. Some polymeric materials have recently gained adequate attention as potential materials for BTE applications, as they are biocompatible, biodegradable, inexpensive, lightweight, easy to process, and recyclable. Polyetherimide (PEI), acrylonitrile butadiene styrene (ABS), and polyamide-12 (PA12) are potential biocompatible materials for biomedical applications due to their excellent physical, chemical, and mechanical properties. The current study presents preliminary findings on the process simulations for 3D-printed polymeric porous scaffolds for a material extrusion 3D printing (ME3DP) process to observe the manufacturing constraints and scaffold quality with respect to designed structures (porous scaffolds). Different unit cell designs (ventils, grid, and octet) for porous scaffolds, virtually fabricated using three polymeric materials (PEI, ABS, and PA12), were investigated for process-induced defections and residual stresses. The numerical simulation results concluded that higher dimensional accuracy and control were achieved for grid unit cell scaffolds manufactured using PEI material; however, minimum residual stresses were achieved for grid unit cell scaffolds fabricated using PA12 material. Future studies will include the experimental validation of numerical simulation results and the biomechanical performance of 3D-printed polymeric scaffolds.Öğe Numerical predictions and experimental validation on the effect of material properties in filament material extrusion(Elsevier Sci Ltd, 2023) Al Rashid, Ans; Koc, MuammerThe numerical prediction of dimensional accuracy and mechanical performance of 3D-printed structures can eliminate or reduce the need to perform trial-and-error experimentation to achieve the desired part quality quickly and at a reduced cost. Therefore, this study focuses on experimental and numerical investigations of the effect of material properties on dimensional control of the material extrusion additive manufacturing process. A thermomechanical model is utilized, validated, and used to predict the part deflections, warpages, and residual stresses in 3D-printed components for two different materials (i.e., polyamide-6 (PA6) and acrylonitrile butadiene styrene (ABS)). In addition, numerical simulations for mechanical testing were performed and validated through experimental investigations. The numerical model considered the effect of material on final product quality and was in close agreement with experimental results. It was concluded that the materials with a lower thermal expansion coefficient (CTE) would provide better dimensional accuracy of 3D-printed parts. In addition, the lower thermal conductivity and temperature variations within the 3D-printed part will further produce precise parts. The controlled ambient environment using a closed chamber can also assist in maintaining desired thermal gradient and avoid non-uniform cooling during the process. Finally, the numerical model accurately predicted the mechanical behavior of 3D-printed samples as validated via experimentation.Öğe Numerical simulations on thermomechanical performance of 3D printed chopped carbon fiber-reinforced polyamide-6 composites: Effect of infill design(Wiley, 2022) Al Rashid, Ans; Koc, Muammer3D printing (3DP) of polymer composite products and solutions mainly relies on experimental techniques for research & development and product/process/system understanding. Several studies experimentally investigated the effect of infill patterns and densities on the mechanical performance of 3D printed polymer composites. However, due to the unlimited design flexibility of 3DP processes and polymer composite recipes, it is vital to explore numerical simulation tools to speed up research and development time and reduce costs. In this study, we present the development of computational modeling for 3D printed polymer composites using a numerical simulation tool (Digimat-AM (R)) to predict the fused filament fabrication process-induced deflections, residual stresses, and warpage in 3D printed specimens. Digimat-AM (R) provides a platform to simulate the fabrication of 3D printed parts, which can assist the designers, engineers, and researchers to predict the manufacturing and resulting product issues beforehand. This study aims to understand the effect of different infill patterns and densities on deflections, residual stresses, warpage, and mechanical properties on 3D printed samples. A significant impact of infill pattern and density is observed on deflections, residual stresses, and warpages from numerical simulation results. In addition, the mechanical testing simulations were performed on the specimens with 3DP process-induced defects obtained from the process simulation results. Finally, the numerical simulation results for mechanical testing were validated and compared with physical testing on 3D printed specimens. The results found a satisfactory agreement where differences remain with an acceptable range of 0.22%-7.27%.Öğe Synthesis and characterization of hematite (?-Fe2O3) reinforced polylactic acid (PLA) nanocomposites for biomedical applications(Elsevier, 2022) Ikram, Hamid; Al Rashid, Ans; Koc, MuammerThis study presents preliminary findings on the performance of the stimuli-responsive PLA/alpha-Fe2O3 nanocomposites under the magnetic stimulus with varying concentrations of hematite (alpha-Fe2O3) nanoparticles. The effect of varying nanoparticle concentrations on the structural and thermal properties was examined using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Subsequently, the magnetic field with various intensities was generated using a vibrating sample magnetometer in a controlled environment. The resulting deformation rate of the nanocomposites was observed in response to changing magnetic fields. The results revealed that the PLA/alpha-Fe2O3 nanocomposites could be potential materials for biomedical applications, i.e., cardiovascular stents, which can provide the desired stimulus to treat post-stenting complications without the need for secondary surgical procedures. In future studies, the synthesized PLA/alpha-Fe2O3 nanocomposites will be adopted for 3D printing (3DP) processes to develop patient-specific cardiovascular stents and to evaluate their biomechanical performance.Öğe Synthesis and characterization of hematite (a-Fe2O3) reinforced polylactic acid (PLA) nanocomposites for biomedical applications (Vol 9, 100331, 2022)(Elsevier, 2023) Ikram, Hamid; Al Rashid, Ans; Koc, Muammer[No abstract available]
