Browsing by Author "Nezhad, Hamed Yazdani"
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Item Open Access Accelerated microwave curing of fibre-reinforced thermoset polymer composites for structural applications: A review of scientific challenges(Elsevier, 2018-09-12) Mgbemena, Chinedum Ogonna; Li, Danning; Lin, Meng-Fang; Liddel, Paul Daniel; Katnam, Kali Babu; Kumar, Vijay Thakur; Nezhad, Hamed YazdaniAccelerated curing of high performance fibre-reinforced polymer (FRP) composites via microwave heating or radiation, which can significantly reduce cure time and increase energy efficiency, has several major challenges (e.g. uneven depth of radiation penetration, reinforcing fibre shielding, uneven curing, introduction of hot spots etc). This article reviews the current scientific challenges with microwave curing of FRP composites considering the underlying physics of microwave radiation absorption in thermoset-matrix composites. The fundamental principles behind efficient accelerated curing of composites using microwave radiation heating are reviewed and presented, especially focusing on the relation between penetration depth, microwave frequency, dielectric properties and cure degree. Based on this review, major factors influencing microwave curing of thermoset-matrix composites are identified, and recommendations for efficient cure cycle design are provided.Item Open Access Black phosphorus: the rise of phosphorene in 2D materials applications(Elsevier, 2024-05-03) Mishra, Raghvendra Kumar; Sarkar, Jayati; Chianella, Iva; Goel, Saurav; Nezhad, Hamed YazdaniFew layers Black phosphorus (BP) and phosphorene are two-dimensional (2D) materials renowned for their adjustable bandgaps, high carrier mobility, and anisotropic conductivity, which make them highly promising for applications in the visible and infrared spectrum. The incorporation of these materials into polymer matrices has led to significant advancements in material science, resulting in nanocomposites with enhanced mechanical, electrical, and optical properties. This article provides a thorough analysis of BP/phosphorene polymer nanocomposites, including synthesis techniques (such as exfoliation methods) and manufacturing approaches. Advanced characterisation techniques are utilised to assess the structure, morphology, and properties of these composites. The article highlights the potential applications of these materials in energy storage (e.g., high-capacity batteries), flexible electronics (e.g., bendable displays), environmental sensing, and emerging biomedical fields such as targeted drug delivery. Furthermore, the article discusses potential solutions to tackle the challenges associated with the scalable, cost-effective production and ambient stability of BP/phosphorene, leveraging recent advancements in engineering research. The conclusion outlines future research directions, emphasising the importance of addressing persistent challenges through technological breakthroughs and exploring potential avenues for further advancement.Item Open Access Borophene: a 2D wonder shaping the future of nanotechnology and materials science(Elsevier, 2024-05-10) Mishra, Raghvendra Kumar; Sarkar, Jayati; Verma, Kartikey; Chianella, Iva; Goel, Saurav; Nezhad, Hamed YazdaniTwo-dimensional (2D) materials have attracted considerable research interest due to their precisely defined properties and versatile applications. In this realm, borophene - a single atomic sheet of boron atoms arranged in a honeycomb lattice - has emerged as a promising candidate. While borophenes were theoretically predicted to have unique structural, optical, and electronic properties, the experimental synthesis of crystalline borophene sheets was first demonstrated on metal substrates in 2015, marking a crucial milestone. Since then, research efforts have focused on controlling the synthesis of semiconducting borophene polymorphs and exploring their novel physical characteristics. This review aims to explore the potential of 2D materials, specifically borophene, in various technological fields such as batteries, supercapacitors, fuel cells, and more. The analysis emphasises meticulous scrutiny of synthesis techniques due to their fundamental importance in realising borophene's properties. Specifically, the high carrier mobilities, tuneable bandgaps, and exceptional thermal conductivity of borophene are highlighted. By providing a comprehensive outlook on the significance of borophene in advancing materials science and technologies, this review contributes to shaping the landscape of 2D material research.Item Open Access Carbon nanotube embedded adhesives for real-time monitoring of adhesion failure in high performance adhesively bonded joints(Springer Nature, 2020-10-08) Bregar, Tadej; An, Donglan; Gharavian, Somayeh; Burda, Marek; Durazo-Cardenas, Isidro; Thakur, Vijay Kumar; Ayre, David; Słoma, Marcin; Hardiman, Mark; McCarthy, Conor; Nezhad, Hamed YazdaniCarbon nanotubes (CNTs) embedded polymers are of increasing interest to scientific and industrial communities for multi-functional applications. In this article, CNTs have been introduced to high-strength epoxy adhesive for enabling in-situ strain sensing in adhesively bonded aluminium-to-aluminium single-lap joints to accurately indicate the onset and propagation of adhesion failure to the evolution of piezo-resistivity in varying mechanical loads. The CNT modified adhesive in bonded joints and the CNT modified adhesive alone have been tested under monothonic and cyclic tensile loads up to ultimate failure. The changes in the piezo-resistivity induced by the CNTs have been monitored in situ with respect to loading. A novel interpretation method has been developed for progressive, instantaneous adhesion failure estimation under cyclic tensile stresses from a resistivity baseline. The method indicates that the in-situ resistivity changes and the rate of the changes with strain, i.e. sensitivity, strongly correlate with the adhesion failure progression, irrespective of the CNT dispersion quality. Moreover, the effect of bond thickness on the evolution of piezo-resistivity and adhesion failure have been studied. It was observed that relatively thin adhesive bonds (0.18mm thickness), possessing higher CNT contact points than thick bonds (0.43mm thicknes), provide 100 times higher sensitivity to varying cyclic loadsItem Open Access Comparison of cooled and uncooled IR sensors by means of signal-to-noise ratio for NDT diagnostics of aerospace grade composites(MDPI, 2020-06-15) Shakeb, Deane; Avdelidis, Nicolas Peter; Ibarra-Castanedo, Clemente; Zhang, Hai; Nezhad, Hamed Yazdani; Williamson, Alex A.; Mackley, Tim; Maldague, Xavier P. V.; Tsourdos, Antonios; Nooralishahi, ParhamThis work aims to address the effectiveness and challenges of non-destructive testing (NDT) by active infrared thermography (IRT) for the inspection of aerospace-grade composite samples and seeks to compare uncooled and cooled thermal cameras using the signal-to-noise ratio (SNR) as a performance parameter. It focuses on locating impact damages and optimising the results using several signal processing techniques. The work successfully compares both types of cameras using seven different SNR definitions, to understand if a lower-resolution uncooled IR camera can achieve an acceptable NDT standard. Due to most uncooled cameras being small, lightweight, and cheap, they are more accessible to use on an unmanned aerial vehicle (UAV). The concept of using a UAV for NDT on a composite wing is explored, and the UAV is also tracked using a localisation system to observe the exact movement in millimetres and how it affects the thermal data. It was observed that an NDT UAV can access difficult areas and, therefore, can be suggested for significant reduction of time and cost.Item Open Access Effect of morphological changes due to increasing carbon nanoparticles content on the quasi-static mechanical response of epoxy resin(MDPI, 2018-10-06) Nezhad, Hamed Yazdani; Thakur, Vijay KumarMechanical failure in epoxy polymer and composites leads them to commonly be referred to as inherently brittle due to the presence of polymerization-induced microcrack and microvoids, which are barriers to high-performance applications, e.g., in aerospace structures. Numerous studies have been carried out on epoxy’s strengthening and toughening via nanomaterial reinforcement, e.g., using rubber nanoparticles in the epoxy matrix of new composite aircraft. However, extremely cautious process and functionalization steps must be taken in order to achieve high-quality dispersion and bonding, the development of which is not keeping pace with large structures applications. In this article, we report our studies on the mechanical performance of an epoxy polymer reinforced with graphite carbon nanoparticles (CNPs), and the possible effects arising from a straightforward, rapid stir-mixing technique. The CNPs were embedded in a low viscosity epoxy resin, with the CNP weight percentage (wt %) being varied between 1% and 5%. Simplified stirring embedment was selected in the interests of industrial process facilitation, and functionalization was avoided to reduce the number of parameters involved in the study. Embedment conditions and timing were held constant for all wt %. The CNP filled epoxy resin was then injected into an aluminum mold and cured under vacuum conditions at 80 °C for 12 h. A series of test specimens were then extracted from the mold, and tested under uniaxial quasi-static tension, compression, and nanoindentation. Elementary mechanical properties including failure strain, hardness, strength, and modulus were measured. The mechanical performance was improved by the incorporation of 1 and 2 wt % of CNP but was degraded by 5 wt % CNP, mainly attributed to the morphological change, including re-agglomeration, with the increasing CNP wt %. This change strongly correlated with the mechanical response in the presence of CNP, and was the major governing mechanism leading to both mechanical improvement and degradation.Item Open Access Estimation of damage thickness in fibre-reinforced composites using pulsed thermography(2018-10-31) Sirikham, Adisorn; Zhao, Yifan; Nezhad, Hamed Yazdani; Du, Weixiang; Roy, RajkumarNon-destructive-testing (NDT), including active thermography, has become an inevitable part of composite process and product verification, post-manufacturing. However, there is no reliable NDT technique available to ensure the interlaminar bond integrity during composite laminates integration, bonding or repair where the presence of thin airgaps in the interface of dissimilar polymer composite materials would be detrimental to structural integrity. This paper introduces a novel approach attempting to quantify the damage thickness of composites through a single-side inspection of pulsed thermography. The potential of this method is demonstrated by testing on three specimens with different types of defect, where the Pearson Correlation Coefficients of the thickness estimation for block defects and flat-bottom holes are 0.75 and 0.85, respectively. This approach will considerably enhance the degradation assessment performance of active thermography by extending damage measurement from currently two dimensions to three dimensions, and become an enabling technology on quality assurance of structural integrity.Item Open Access A finite element study of fatigue crack propagation in single lap bonded joint with process-induced disbond(Elsevier, 2018-09-09) Liu, Yiding; Lemanski, Stuart; Zhang, Xiang; Ayre, David; Nezhad, Hamed YazdaniThis paper presents a method for predicting fatigue crack propagation in adhesive bonded composite joints with an initial full-width disbond using finite element analysis and numerical integration of the material's fatigue crack growth rate law. Fatigue tests were conducted on single lap joints. Crack lengths were monitored from four runout corners. In-situ crack growth measurements were performed by ink injection to identify the crack front profile during fatigue loading. The crack growth was modelled using a fracture mechanics criterion considering two different crack propagation patterns. The material's fatigue crack growth rate law was determined experimentally using the standard double cantilever beam and end notch flexure specimens. Using the total strain energy release rate and the two crack scenarios, the numerical model predicted the lower and upper bounds of the measured fatigue crack growth rates of the lap joint.Item Open Access Nanomaterial integration in micro LED technology: enhancing efficiency and applications(Elsevier, 2024-03-27) Mishra, Raghvendra Kumar; Verma, Kartikey; Chianella, Iva; Goel, Saurav; Nezhad, Hamed YazdaniThe micro-light emitting diode (µLED) technology is poised to revolutionise display applications through the introduction of nanomaterials and Group III-nitride nanostructures. This review charts state-of-the-art in this important area of micro-LEDs by highlighting their key roles, progress and concerns. The review encompasses details from various types of nanomaterials to the complexity of gallium nitride (GaN) and III nitride nanostructures. The necessity to integrate nanomaterials with III-nitride structures to create effective displays that could disrupt industries was emphasised in this review. Commercialisation challenges and the economic enhancement of micro-LED integration into display applications using monolithic integrated devices have also been discussed. Furthermore, different approaches in micro-LED development are discussed from top-down and bottom-up approaches. The last part of the review focuses on nanomaterials employed in the production of micro-LED displays. It also highlights the combination of III-V LEDs with silicon LCDs and perovskite-based micro-LED displays. There is evidence that efficiency and performance have improved significantly since the inception of the use of nanomaterials in manufacturing these.Item Open Access Nanostructured ZnO-CQD hybrid heterostructure nanocomposites: synergistic engineering for sustainable design, functional properties, and high-performance applications(Wiley, 2024-05-03) Mishra, Raghvendra Kumar; Chianella, Iva; Sarkar, Jayati; Nezhad, Hamed Yazdani; Goel, SauravHybrid nanocomposites integrating nanostructured zinc oxide (ZnO) and carbon quantum dots (CQDs) with designed heterostructures possess exceptional optical and electronic properties. These properties hold immense potential for advancements across diverse scientific and technological fields. This review article investigates the synthesis, properties, and applications of ZnO-CQD heterostructure nanocomposites. Recent breakthroughs in fabrication methods are examined, including hydrothermal, microwave-assisted, and eco-friendly techniques. Key preparation methods such as sol-gel, co-precipitation, and electrochemical deposition are discussed, emphasizing their role in controlling heterostructure formation. This review analyses the impact of heterostructures on optical and electronic properties, such as fluorescence, photoluminescence, and photocatalytic activity. Synergistic interactions between ZnO and CQDs within heterostructures are highlighted, demonstrating how they lead to substantial performance improvements. Applications of ZnO-CQD heterostructures span solar cells, LEDs, photodetectors, water purification, antimicrobial treatments, gas sensing, catalysis, biomedical imaging, drug delivery, environmental sensing, and energy storage. Insights are provided into refining synthesis methods, enhancing characterisation techniques, and broadening the application landscape. Challenges like stability are addressed, along with strategies for optimised performance and practical implementation.Item Open Access Strain self-sensing tailoring in functionalised carbon nanotubes/epoxy nanocomposites in response to electrical resistance change measurement(SSRN, 2020-10-26) An, Donglan; Nourry, Jim; Gharavian, Somayeh; Thakur, Vijay Kumar; Aria, Adrianus Indrat; Durazo-Cardenas, Isidro; Khaleque, Tasnuva; Nezhad, Hamed YazdaniCarbon nanotubes (CNTs) are inherently multifunctional, conductive and possess piezo-resistive characteristics. Aiming at the multi-functionality of materials, nanocomposites made of epoxy resin with embedded CNTs are a promising solution for strain self-sensing applications. A critical parameter to achieve repeatable and reliable measure is the CNTs dispersion state in the resin. This study investigated the effect of CNTs concentration (0.01 wt% and 0.1 wt%), with different loading of surfactant Triton X-100, (0.0%, 0.2%, 0.5% and 1.0%) on strain sensing in terms of sensitivity and linearity based on electrical resistance data. The CNTs were synthesised directly using an injection floating catalyst chemical vapor deposition (ICCVD) process and their quality was characterised by Raman spectroscopy and scanning electron microscopy. Only the epoxy modified with 0.1 wt% CNTs exhibited sufficient piezo-resistivity for the resistance measurements, and those with 0.01 wt% CNTs did not show sufficiently measurable conductivity so were excluded in our study, since their CNTs were highly entangled, and conductive network failed to be established. It was observed that, with 0.1 wt% CNTs, adding 0.5% content of the surfactant improved gauge factor. With more content of the surfactant (1.0 %), surprisingly, we observed a drop of gauge factor by the order of two. Therefore, by comparing the conductivity change between 1.0% and 0.5% surfactant, we postulated that the relatively high content surfactant has reached critical micelle concentration, and negatively affects CNTs dispersion state. The research presented in this article shows that moderate content of surfactant could improve piezo-resistivity gauge factor while excessive surfactant could cause adverse effect.Item Open Access Tailoring of thermo-mechanical properties of hybrid composite-metal bonded joints(MDPI, 2021-01-06) Khaleque, Tasnuva; Zhang, Xiaolong; Thakur, Vijay Kumar; Aria, Adrianus Indrat; Nezhad, Hamed YazdaniMetallic substrates and polymer adhesive in composite-metal joints have a relatively large coefficient of thermal expansion (CTE) mismatch, which is a barrier in the growing market of electric vehicles and their battery structures. It is reported that adding carbon nanotubes (CNTs) to the adhesive reduces the CTE of the CNT-enhanced polymer adhesive multi-material system, and therefore when used in adhesively bonded joints it would, theoretically, result in low CTE mismatch in the joint system. The current article presents the influence of two specific mass ratios of CNTs on the CTE of the enhanced polymer. It was observed that the addition of 1.0 wt% and 2.68 wt% of multi-walled CNTs (MWCNTs) decreased the CTE of the polymer adhesive from 7.5×10−5 °C−1 (pristine level) to 5.87×10−5 °C−1 and 4.43×10−5 °C−1, respectively, by 22% and 41% reductions.