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Solar energy is the centre of attention and major need of the world. The advancement in the photovoltaic devices plays the key role in the path of solar energy applications. The progress in the perovskite solar cell technologies in the direction of their theoretical power conversion efficiency necessitates elusive control above the carrier dynamics all over the whole device. In the present investigation, a comparative study via SCAPS simulation has been done for the optimization of the device in the light of high power conversion efficiency of organic–inorganic perovskite-based photovoltaic solar cells. Perovskite absorber layers CH3NH3PbI3 and CH3NH3SnI3 are sandwiched in between the TiO2 as electron transport layer (ETL) and spiro-OMeTAD as hole transport layer (HTL) to design the hetrostructures for the simulation. We have achieved enhancement in the power conversion efficiencies of both the devices as compared to the reported experimental and theoretical studies previously.

Lead free and environment friendly, light absorbing material is in high demand for the photovoltaic perovskite solar cell devices. The double perovskite La2NiMnO6 have the centre of attention for this demand. The present review is focused to discuss briefly the progress and challenges in the structural and magnetic properties of La2NiMnO6 in bulk, nano and thin film phases. The structural changes of La2NiMnO6 are highly interesting and have the direct correlation with the magnetic properties. On the basis of these transformations in the structure, efforts have been made to discuss several scientific progresses into technical novelties. This short review article is critically dedicated on reviewing the progresses, openings, and upcoming challenges in perovskite solar cell devices.

This paper presents synthesis and study of Structural, Optical, and Photocatalytic properties of bismuth ferrite (BFO) and nickel doped bismuth ferrite (BiFe1-xNixO3) nanoparticles. The synthesis of BiFeO3 and BiFe1-xNixO3 (x = 0.02, 0.04) are done by Sol-Gel method. After synthesis the samples of pure and transition metal ion (Ni) doped bismuth ferrite have been studied by using X-ray diffractometer (XRD), X-ray Photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscope and Raman Spectroscopy. Optical properties are studied by using UV–vis spectroscopy using different wavelengths (range 300–800 nm). Photocatalytic properties are also studied by degradation of MB dye using prepared samples as photocatalyst. XRD patterns shows that all the prepared samples are crystalline and crystallinity increased by Ni-doping and shifts in XRD peaks by Ni-doping shows the distortion in the structure of BFO. Raman spectroscopy also indicates the rhombohedral distorted structure of Ni-doped BFO in R3C space group. FESEM micrographs shows that Ni-doped BFO has polyhedral and spherical shape grains and Ni doping cause reduction in grain size. Optical band gap reduced due to Ni-doping is shown by the UV–Vis spectroscopy results and Tauc’s plots. The increase in reduction of MB dye due to Ni-doping shows the enhanced photocatalytic properties of BFO by Ni doping.

Control on the size of copper oxide (CuO) in the nano range is a highly motivating approach to study its multifunctional nature. The present investigation reports a sol-gel derived Ni doped CuO nanoparticles (Cu1-xNixO). Rietveld refinement of the XRD spectra confirms the formation of single monoclinic phase of Cu1-xNixO nanoparticles having crystallite size within the range of 19–21 nm. Raman spectra show the presence of characteristics Raman active modes and vibrational bands in the Cu1-xNixO samples that corroborate the monoclinic phase of the samples as revealed by refinement of XRD data. The estimated band gap of pure CuO is found to be ∼1.43 eV, which decreases with the increase of dopant concentration into CuO matrix. This result is in line with estimated crystallite size. Magnetization curves confirm the weak ferromagnetic nature of Cu1-xNixO nanoparticles which reveal the DMS phase. This weak magnetic nature may be induced in the samples due to the exchange interaction between the localized magnetic d-spins of Ni ions and carriers (holes or electrons) from the valence band of pristine CuO lattice. Replacement of Cu+2 by Ni+2 ions into the host CuO lattice induces the magnetization. The quantified value of squareness ratio (S

In comparison to the traditional reinforced composites, Friction stir processed composites have emerged to be more promising because of their better properties such as strength, hardness, ductility...

The development of smart negative electrode materials with high capacitance for the uses in supercapacitors remains challenging. Although several types of electrode materials with high capacitance in energy storage have been reported, carbon-based materials are the most reliable electrodes due to their high conductivity, high power density, and excellent stability. The most common complaint about general carbon materials is that these electrode materials can hardly ever be used as free-standing electrodes. Free-standing carbon-based electrodes are in high demand and are a passionate topic of energy storage research. Electrospun nanofibers are a potential candidate to fill this gap. However, the as-spun carbon nanofibers (ECNFs) have low capacitance and low energy density on their own. To overcome the limitations of pure CNFs, increasing surface area, heteroatom doping and metal doping have been chosen. In this review, we introduce the negative electrode materials that have been developed so far. Moreover, this review focuses on the advances of electrospun nanofiber-based negative electrode materials and their limitations. We put forth a future perspective on how these limitations can be overcome to meet the demands of next-generation smart devices.

The chiral behavior of the macroscopic and nanoscopic objects is ubiquitous. In the last ten years, the research on chiral inorganic nanomaterials has witnessed tremendous growth due to their shape, size, crystal facets-controlled unparalleled physical, chemical, optoelectronic, and bio-compatibility features. Due to the quantum confinement, the chiral nanomaterials exhibit high anisotropy factors, and therefore there has been an upsurge in research activities related to chiroptical and (bio)recognition properties of optically active inorganic nanomaterials. Advancement in synthesis and characterization technologies has made it possible to prepare more and more complex multi-functional materials. Inorganic nanoparticles exhibit fascinating semiconducting or metallic behavior and when combined with chirality, another degree of freedom over achiral systems, their usability in various devices enhances drastically. In this Review, we discuss different chemical routes to transfer chirality from intrinsic chiral systems into achiral nanomaterials for optoelectronics and bio-applications, in the light of recent experimental findings. However, to date, imprinting chirality, device fabrication, scalability, long-term stability, and reproducibility remain challenging tasks that need to be addressed. As the synthesis and growth mechanisms of chiral inorganic systems could be found in literature, here we shed light only on the complimentary metal-oxides semiconductors (CMOS), and bio-compatibility of either intrinsic or imprinted chiral nanomaterials and their potential application in next-generation chiroptical devices. We also discuss feasible strategies to resolve existing issues related to the integration into devices and their operational aspects.

Most of automotive and aerospace industries use journal bearing as support for rotating elements. It is because of such bearings exhibits prolonged material life and has better performance. In this research, material modeling and numerical simulation of an elliptic bore journal bearing with isotropic roughness is carried out for load carrying capacity (LCC) using finite difference method. The LCC is a governing parameter, which decides the bearing material and its implication for a particular bearing application. Load is evaluated by integrating the hydrodynamic pressure over bearing area. Subsequently, it is observed that bearing load depends on eccentricity(e), Non-circularity (G), L/D ratio (β) and roughness parameter (Y) due to which there is a complex effect of all these parameters on bearing performance and therefore on material selection. A grey based Taguchi optimization model is developed with four factors at two levels, to find the best combination of bearing parameters on the LCC. Optimized load carrying is achieved at e2-G1-β2-Y1 condition. The isothermal and the thermal non-dimensional loads are 7.0605 and 3.3 respectively in this condition.

Engine pistons are subjected to high gas pressure force on the crown. Such compressive force, helps the piston to gain inertia for reciprocation. But suitable materials are required to sustain higher temperature(500 °C) and pressure (120 bar) environments in engine. Aluminum based alloy or cast iron are selected for such application. To enhance material life, sometimes coating is done to reduce the effect of thermal and stress behavior. This study aims to investigate a combination effect of coating and geometrical modification on the material strength of an engine piston. A piston head, with a bowl shape was analyzed by finite element technique, considering the whole piston is coated with TiSiCN thin layer. The analysis was developed to predict the material strength of two types of pistons: uncoated flat crown and a TiSiCN coated bowl on the crown. A comparative analysis was carried out to summarize the benefits of such modifications in a piston. The result showed a 33.96% reduction on stress level and 11.9% reduction in deformation achieved due to such coating process.

The modern era of digital computing systems is deeply embedded around memory devices, which store an ocean of information accessible by an electronic gadget. Such electronic circuitry can be mimicked by molecules that became known to the scientific community over the last two decades. However, their mechanistic studies, fast switching events, reproducibility, and scaling-up approaches are crucial points for such molecular devices to have practical applications. Among the well-explored systems, redox-based resistive switching memories (RRAM) are the most prosperous research domain, expressly for technological augmentation. In situ stabilization of electrical charges on the molecule for the subsequent reduction of the frontier molecular orbital's energy gap, can be an excellent method to overcome the slow switching speed of prototype devices. The recent extension of resistive memory to memristors has also offered enormous charge storage capacity and processing ability to overcome Moore's limitation law and the Von Neumann bottleneck issue. Thereby, the central objective of the present review is to showcase the recent progress in the fabrication of devices incorporating inorganic, organic, and redox-active molecules, either in self-assembled monolayers or many molecules assembled between two electrical contacts followed by stimuli-responsive current–voltage (I–V) analysis. Solid-state molecular memory devices as a ‘proof-of-concept’ might be prolific in future applications.

Carbon nanotubes (CNTs) have been synthesized by a simple and efficient pyrolysis technique, and composites of CNTs with PEDOT:PSS, and with P3HT:PCBM blend have been prepared by a modest solution treatment. Bulk heterojunction organic photovoltaic cell (OPVC) has been fabricated by spin coating technique with configuration ITO/PEDOT:PSS/P3HT:PCBM/Al to serve as reference OPVC. Three more OPVCs have been fabricated by the same procedure, the first one with CNTs/PEDOT:PSS composite replacing PEDOT:PSS, second one with CNTs/P3HT:PCBM composite replacing P3HT:PCBM blend, and the third one with both replacements. The performances of all the OPVCs at room temperature have been compared and CNTs have been observed to cause extraordinary increment in the power conversion efficiency (PCE) as well as other electrical parameters of all the devices depending on the layer in which they have been incorporated. To extend the study for understanding further advantages of CNTs incorporation in fighting against degradation, all the fabricated OPVCs have been exposed to open atmosphere and their electrical properties have been measured at room temperature in regular intervals. Encouragingly positive outcomes have been attained, demonstrating not only a well maintained enhancement in the PCE, but also a considerably improved device stability. The best performing OPVC has achieved 24% more PCE and 67% more lifetime in open atmosphere than the reference device, which clearly does indicate the significance of applications of filler CNTs to improve not only the performance but also the stability of OPVCs.

Polymer nanocomposites with vital reinforcements of conductive fillers have evinced as next-generation high-performance materials with multi-functional applications. Herein, we report the facile synthesis of thermally stable, highly electrically conducting polyaniline multi-walled carbon nanotubes (PANI/MWCNT) nanocomposites doped in two different protonic acids, i.e. hydrochloric acid (HCl) and sulphuric acid (H2SO4). The doping acids significantly affect the electric and dielectric properties of conducting polymer nanocomposites. The paper probes in the synergistic effects of MWCNTs and the effect of doping acid on the thermal stability, conductivity and dielectric properties of the nanocomposites based on PANI nanofibres. The structural, morphological, optical, thermal and electrical properties were evaluated through X-ray diffraction, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, UV–Vis spectroscopy, thermogravimetric analysis and two-point probe technique. Ascribed to the high interfacial interaction between PANI and MWCNT, and considering the effect of doping acids, nanocomposites with high thermal stability, enhanced conductivity and high dielectric constant that can store large electrical charges have been synthesized by surfactant-assisted, in situ oxidative polymerization of aniline, in the presence of potassium persulfate as oxidant. The micellar structure of surfactant assists the dispersion of MWCNTs as well as the formation of PANI/MWCNT tubular structures. The effect of surfactant below and above critical micelle concentration was also studied. This complete study would affirm such a nanocomposite which procures excellent electrical and dielectric properties for microelectronic applications.

In this paper, the experimental analysis of two types of corrugated plate solar collector (CPSC) using water as working fluid has been done. Two similar designs and dimensions of CPSC but different materials of absorber plates have been investigated, the collector1 is copper and collector 2 is aluminium. The performance of energy, exergy and total heat loss coefficient of CPSC were analysed and compared. Thermal performance of CPSC depends on many parameters such as outlet collector temperature, absorber plate temperature, temperature difference, inlet collector temperature, atmospheric temperature, mass flow rate (MFR), solar radiation, wind speed and absorber plate material. The three MFR values of 0.0167 kg/s, 0.025 kg/s and 0.033 kg/s were considered in this experimental setup. The thermal performances of these two types of solar collectors were investigated. Also, a comparison between the performance of these two types of solar collector at various MFR was done. Experimental results show that the use of copper-based CPSC could improve the thermal efficiency compared to the use of aluminium based CPSC. The maximum energy and exergy of copper and aluminium based CPSC was found at MFR 0.033 kg/s. Results show that as the water MFR is increased from 0.0167 kg/s to 0.033 kg/s, the thermal efficiency of collector made of copper and aluminium increases.

The concept of molecular electronic devices (MEDs) has evolved since the first theoretical report was published in 1974. This theoretical article laid the foundation for understanding charge-transport phenomena by utilizing either a single molecule or numerous molecules sandwiched between two electrical conductors. Since then, many research groups have engaged in molecular junction fabrication using a variety of molecules including organic, inorganic, and organometallic molecules, polymers, and biomolecules that can mimic the electronic functions of traditional silicon-based devices. To date, most of these molecular junctions have been constructed using well-explored molecular assemblies of thiolated derivatives adsorbed mostly on Au substrates. However, the Au-S bond is not considered to be a true covalent bond in view of its surface bond energy, which is ∼1.9 eV, much less than pure covalent bond energy. Additionally, Au-S interfaces suffer from poor reactivity and instability over time; thus, they are not suitable for real world applications. Therefore, an alternative approach for the fabrication of molecular electronic junctions must be envisioned to address all the difficulties mentioned above. Herein, we summarize the most recent experiential outcomes to demonstrate how electrochemical techniques can be employed to form robust molecular layers on various substrates including Au, ZnO, SnO2, H-terminated Si, and conductive carbon electrodes that are suitable for the fabrication of reliable molecular electronics devices for charge-transport studies. This fascinating electrochemical technique is appropriate for producing not only homostructure but also heterostructure molecular layers with desired thicknesses. We also discuss the pros and cons of the electrochemical process for growing molecular layers in the Conclusion and outlook section.

Present work studies the effect of particle reinforcement on fracture toughness of bio-composites. The filler used has been taken as rice husk. Epoxy resin has been taken as matrix material. Composites with varying filler loading of 10, 20, 30 and 40 wt.% were fabricated. The fracture toughness was seen to be increasing with increase in filler loading. However beyond 20% there was a decrease in fracture toughness with increase in filler loading. The effect of fibre treatment on toughness was also observed. Rice husk fibres pre-treated with NaOH were used. It was observed that fracture toughness further improved due to treatment. The increase in fracture toughness was significant. Fracture toughness increased from 1.072 to 2.7465 MPa√mm for 20% reinforcement and after treatment it increased to 2.876 MPa√mm. It was observed that concentration of treatment media also affects the fracture toughness. Further the effect of hybridization was observed by addition of rice husk ash as a secondary reinforcement. The fracture toughness of the resulting composites was remarkably higher than that of pure epoxy.

In this paper, an experimental analysis on modified and conventional dual-purpose solar collector (DPSC) using water/air as working fluid. In the conventional DPSC (Type 1), flat absorber plate, co...

In the present study, thermal analysis of two heat exchangers, namely a shell and wire coil-inserted helical coil tube heat exchanger and a shell and without wire coil-inserted helical coil tube he...

During the manufacture of various components, a number of machining operations are carried out. It is essential to study the cutting process for economic aspects of the manufacturing of the components. To investigate the performance of cutting tool during the cutting, the measurement of cutting forces is essential. This helps the analysis of material cutting. The tool force measurement is an essential tool to analyze the process of material cutting. These test results are used to solve shop floor problems such as tool performance, load exerted on the machine, or on the jigs and fixtures. Effect of feed rate and cutting speed on cutting forces of almond shell and coconut fiber biocomposite was investigated using 10, 20, 30, 40, and 50 weight percentages of almond shell particle and 2, 4, and 6 weight percentages of coconut fiber mixed with epoxy resin. It was found that the cutting force increases at higher rotational speed due to quick carrying out of heat generated during cutting process through tool or chips and hence thermal softness of chips increases the cutting force at higher rotational speed.

Molecules are fascinating candidates for constructing tunable and electrically conducting devices by assembling either single or ensemble of molecules between two electrical contacts followed by current-voltage (I-V) analysis which is often termed 'molecular electronics'. Recently, there has been also an upsurge of interest in spin-based electronics or spintronics across the molecules offering an additional scope to create ultra-fast responsive devices with less power consumption and lower heat generation using the intrinsic spin property rather than electronic charge. Researchers have been exploring this idea of utilizing organic molecules, organometallics, coordination complexes, polymers, and biomolecules (proteins, enzymes, oligopeptides, DNA) in integrating molecular electronics and spintronics devices. Although several methods exist to prepare molecular-thin films on a suitable electrode, the electrochemical potential-driven technique emerges as highly efficient in various aspects. The key focus of this review is to describe recent advances in the electrochemical potential-driven growth of nanometric molecular films of various molecules on technologically relevant substrates, including non-magnetic and magnetic electrodes to investigate the stimuli-responsive charge and spin transport phenomena. Although there have been several bottlenecks with the scaling-up, fabrication and operational mechanism, still we foresee that the molecular devices can hold the potentials to compete against physical and economic barriers for commercial success soon.

Natural fibers from agricultural waste have received more attraction than traditional synthetic fibers in recent years. In present investigation epoxy/rice husk composite has been fabricated to utilize the agricultural waste which can be recycled easily and overcome the pollution problems due to smoke and fine silica ash. Study of interfacial bonding and dispersion of rice husk in epoxy resin has been studied through scanning electron microscope image. Characterization of fabricated composites has been done by mechanical properties. Ultimate tensile strength, Young’s Modulus and hardness are highest at 10 wt.% of rice husk particle and their values are 66.5 MPa, 616.46 MPa and 16.8 HV respectively. Machinability of epoxy/rice husk composites has been determined through drilling operation. Effect of feed rate (0.1, 0.2 and 0.3 mm/rev), speed (300, 600 and 900 rpm) and wt.% of reinforcement (10, 15 & 20) have been studied on machinability of epoxy/rice husk composites. Taguchi L27orthogonal array has been applied to conduct the experiments to evaluate the performance characteristics viz thrust force and torque. Weight percentage was found the most significant factor for machinability followed by feed rate and speed.

Majority of studies has been reported in literature in recent years on performance of shell and helical coil tube heat exchanger. The present work attempts to design and analyze experimentally hot ...

A high-performance ultraviolet photodetector has been successfully fabricated based on new CuO/CdSe core-shell nanowires (NWs). The obtained modulated optical band gap due to quantum confinement effect has the capability to detect photons with energies (3.96 eV) significantly larger than the band gap of CuO (1.2 eV) and CdSe (1.7 eV), which is mainly attributed to the abrupt interface between the CuO core and CdSe shell. The fabricated CuO/CdSe core-shell heterostructure NWs as photodetector device showed responsivity 0.63A/W with external quantum efficiency approximately 3.14 × 102% under illumination of wavelength 254 nm. The strong response of CuO/CdSe NWs photodetector is explained by the Type-II band alignment which cause the separation of photo generated electron–hole pairs and their charge transfer at the junction.

Pr3+ and Ti4+ doped BiFeO3; Bi1-xPrxFe0.80Ti0.20O3 (x = 0.05, 0.10 and 0.15) ceramics were prepared by two stage solid state sintering method. The X-ray diffraction shows large structural distortio...

In the present scenario, conducting and lightweight flexible polymer nanocomposites rival metallic and inorganic semiconducting materials as highly sensitive piezoresistive force sensors. Herein, we explore the feasibility of vertically aligned carbon nanotube (VACNT) nanocomposites impregnated in different polymer matrixes, envisioned as highly efficient piezoresistors in sensor applications. Polymer nanocomposites are selectively designed and fabricated using three different polymer matrixes, i.e., polydimethylsiloxane (PDMS), polyurethane (PU), and epoxy resins with ideal reinforcement of VACNTs to enhance the thermal stability, conductivity, compressibility, piezoresistivity, and sensitivity of these nanocomposites. To predict the best piezoresistive force sensor, we evaluated the structural, optical, thermal, electrical, mechanical, and piezoresistive properties of the nanocomposites using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), I-V measurements, compressive stress-strain measurements, hysteresis, sensitivity, and force studies. The results demonstrate that the PDMS/VACNT nanocomposite is capable of sustaining large force with almost complete recovery and enhanced sensitivity, thereby fulfilling the desirable need for a highly efficient conductive and flexible force sensor as compared to PU/VACNT and epoxy/VACNT nanocomposites.

This paper studies the effect of addition of rice husk ash on the wear characteristic of rice husk-reinforced epoxy-based composites. Rice husk ash is the product of thermal degradation of rice husk. The rice husk ash is 90% silica, a hard material. In a previous paper, the rice husk was optimized for mechanical properties. The effect of pre-treatment with NaOH was also studied. In continuation of the previous work, rice husk ash was added as a second reinforcement. Tribological studies are important as there is excessive waste of material due to wear and tear. Silica being a hard material can improve the wear characteristics, and so silica derived from natural resource was used for the purpose. It was observed that the wear characteristics improved due to rice husk ash addition; however, for low level of filling at higher filling level, the wear life started deteriorating. From the SEM micrographs, it is seen that at higher filler level, the adhesion between different constituents was improper resulting in decreased wear characteristics. However, rice husk ash is a viable option for improving wear performance.

To understand the effect of attrition, a series of experiments were conducted in CFB test setup installed at CSIR-CMERI Durgapur using common silica sand. Using standard sieves, three different samples were prepared, containing sample size between 0.106–0.425, 0.212–0.600, and 0.300–0.800 mm of mean Sauter diameter 0.314, 0.414, and 0.520 mm, respectively. Five sets of experiments were conducted for each sample and its mean value is presented in this paper. The attrition of bed particles was found to be higher for larger particles. Sample-III showed the greatest reduction in size as it contained most of the larger particles initially, which got reduced considerably after stipulated run time. It was found from the set of experiments that the mean Sauter diameter for sample-I, II, and III (0.314, 0.414, and 0.520 mm) reduced to 0.312, 0.410, and 0.513 mm, respectively.

The current work designed to fabricate and evaluate self-nanoemulsfying oil formulations (SNEOFs) of Efavirenz (Efz) a BCS class II drug with the objective of increasing its solubility as well as i...

Effect of ionic liquid functionalized multiwalled carbon nanotubes (IL-MWCNTs) on mechanical, thermal and electrical properties of MWCNTs-reduced graphene oxide (rGO)/PMMA nanocomposites is investigated. IL-MWCNTs-rGO/PMMA hybrid nanocomposites are prepared by solvent-casing method. Incorporation of IL-MWCNTs improved the tensile strength and modulus by 119% and 58% respectively at 0.5 wt.% than that of PMMA due to better load transfer from PMMA to IL-MWCNTs-rGO. Enhancement in thermal stability is also occurs with incorporation of IL-MWCNTs in rGO/PMMA composite due to strong interaction provided by IL-MWCNTs with the polymer matrix. IL-MWCNTs-rGO/PMMA hybrid nanocomposites also shows more electrical conductivity than IL-MWCNTs/PMMA composite.

Mesoporous tin oxide was prepared by template assisted and template-free methods. As-prepared materials were calcined at various temperatures to generate different nature (Bronsted and Lewis), amount and strength of acidic sites. The physico-chemical properties of the catalysts were studied by XRD, N2 sorption, pyridine-FTIR, NH3-TPD, DRS UV-vis, TGA, SEM, TEM, 1H MAS and 119Sn MAS NMR analyses. The catalytic behavior of mesoporous tin oxide catalysts was evaluated for acetalization and ketalization of glycerol with benzaldehyde and acetone respectively under solvent free conditions. The catalytic performance of mesoporous tin oxide was compared with that of other conventional solid acid catalysts namely H-ZSM-5, H-mordenite, H-beta, Al-MCM-41, Al-SBA-15 and Al-TUD-1. The efficiency of mesoporous tin oxide was also tested for cyclohexene epoxidation reaction. The catalyst prepared by template assisted method showed excellent catalytic performance compared to other catalysts due the difference in nature and amount of acidic sites in the catalyst. Meso-SnO2-T-350 was stable and reusable catalyst for four cycles without any appreciable loss in activity, and therefore it offers a good catalyst for potentially wide applications.

Adhesive bonded lap joint is considered to be better substitute to riveted or welded joints for aerospace, marine and structural applications. It is due to the ability to develop relatively lower stress concentration and fatigue severity in highly dynamic environment. In real practice, there are defects present in the joint interface that decide the strength and durability of the component. Hence, it is required to understand the joint strength with different defect geometries. In this paper, a combined experimental and finite element method is conducted to evaluate the strength of lap joint of Al-alloy flat plate, pre-embedded with defects of various geometries: square, rectangle, circular and elliptical. The results of experimental and FEM analysis are converging, and indicate the clear variation of strength due to different type of defects. It encourages further analysis.

Friction stir welding (FSW) is a solid-state joining which reduces the structural weight significantly and hence it has received worldwide attention for the joining of aluminium alloys. In this paper, fatigue tests and finite element analysis were employed to study the mechanical and fatigue properties of a friction stir welded T-joint of 19501 aluminium alloy. An LS-2 FSW machine with 100 kN capacity was used to fabricate the T and butt joints. The tensile properties of the friction stir welded joint show that there is a marginal reduction of about 5% in strength and ductility as compared to an un-welded 19501 aluminium alloy. S-N test results of theT-joint specimen at two stress ratios of 0 and −1 showed that there was a reduction of 15% in the fatigue strength due to the change of stress ratio from 0 to −1. The effect of mean stress can be well approximated using Goodman’s criterion as compared to Gerber’s or Soderberg’s criteria. The predicted fatigue lives from the proposed model using the Palmgren-Miner rule (PMR) were found to be within reasonable accuracy. Micrographs shown for the fracture surfaces of the retreating side, mid-weld zone and the advancing side of the T-joint indicate that fracture surfaces are a mixture of dimple and cleavage features.

There is an extensive global effort to replace fossil fuel with blended fuel within existing engine configuration, yet conformed to available infrastructure. Though blended alcoholic fuel is able to reduce carbonated emissions (CO, CO2, unburnt HC), the NOx level increased significantly due to enhanced exhaust temperature resulted out of better combustion. At Green Engine Technology Center, new exhaust mufflers are fabricated with/without perforation to find out if new design of muffler develops less temperature. The main objective of this study is to investigate feasibility of using perforation in diminishing surface temperature. To achieve this, a computational fluid dynamics model is developed to study the effect of perforation on exhaust performance of a turbo pipe type straight and elliptic muffler, fitted to engine running on petrol-methanol blend. The CFD analysis is done through a pressure based solver to study the effect of perforation on back pressure, density, temperature. Prior to the result analysis, the model is validated with a fabricated chamber type prototype muffler fitted to a four stroke single cylinder petrol engine. The temperature thus measured is matching with the simulated temperature. The muffler performance parameters such as back pressure, temperature, density, velocity stream line are studied for different blends (5%, 10%, 15%) of petrol and methanol. Clear variations of these parameters are observed between non perforated and perforated type turbo pipe mufflers.

The statistical aspect of mode I, mode II and mixed mode I/II fracture toughness of epoxy based bio-composite reinforced with 20 wt% walnut shell particle and 10 wt% coconut fiber is studied. The bio-composite is fabricated by the squeeze casting method. A series of fracture tests are conducted on hybrid bio-composite using three point bend, four point bend and semicircular arc bend specimen. The statistical distribution of normalized geometry parameters, T stress, crack tip plastic zone size, particle and fiber size are studied. Generalized maximum tangential stress criterion is modified considering the stochastic nature of the geometry and strength parameters assuming them to follow two parameters Weibull probability distribution. The model developed is applied to the bio-composite and predicted results are compared with the experimental values. Very good agreement is found between the experimental results and predicted results. The variability in the fracture toughness values are correlated with the particle and fiber size determined from scanning electron microscopy. Keywords: Fiber, Hybrid, Fracture toughness, Statistical properties/methods

In this study, the mechanical properties and fatigue life of 19501 aluminum alloy friction stir welded T-joint is investigated. Tensile properties of friction stir welded joint show that there is a marginal reduction of about 5% in strength and ductility as compared to unwelded 19501 aluminum alloy. Fatigue test results of T-joint specimen at two stress ratios of 0 and -1 show that there is a reduction of 15% in fatigue strength due to change of stress ratio from -1 to 0. Also, higher variation is seen in fatigue strength in low cycle zone than the high cycle zone. Effect of mean stress on fatigue life is discussed on the basis of different mean stress effect models. Morrow’s mean stress effect model is found to be better than other models. Micrographs from the fracture surfaces of retreating side, mid weld zone, and advancing side of the T-joint indicates that fracture surfaces are cleavage fracture. Different sizes of inter-metallic bonding are seen in the micrographs, which indicate that fracture is initiated due to breaking of the brittle inter-metallic bonding.

In the past few decades utilization of agricultural wastes as reinforcing materials with polymer matrices has increased. However, the improper adhesion between the incompatible matrix and fibre has been inimical to the proper utilization of this abundant, naturally occurring resource. Mercerization of fibres can be an effective technique to improve the compatibility between the two. In the present case rice husk flour was pre-treated with NaOH solution of varying concentrations and the effects on the mechanical properties was observed. The adhesiveness between the matrix and the fibre improved as is evidenced by the increase in mechanical strength of the composite. It was observed that all the properties increased as the concentration was increased upto 8%. However, beyond 8% there is a decrease in these mechanical properties which can be attributed to the severe deterioration of rice husk due to alkali treatment.

Polymer composites of virgin high density poly ethylene (HDPE) and virgin polypropylene (PP) are prepared. PP of weight% of 20, 30 and 50 are reinforced to HDPE in the form of pellets. They are converted into raw polymer sheets using a two roll milling machine. The prepared raw sheets have undergone compression moulding to fabricate polymer sheets to study electrical properties like dielectric strength, surface resistivity and volume resistivity at atmospheric temperature and pressure. Result shows dielectric strength and volume resistivity decreases with addition of PP to HDPE, whereas surface resistivity increases. Crystal growth rate is observed using a cross polarised microscope (PLM). The microscopy results reveal, the PP crystallizes faster than HDPE and the growth rate declines for the polyblend; showing non-uniform and hazy spherulitic structure.

Herein, a simple, cheap and easily scaled-up procedure to obtain reduced graphene oxide from exfoliated graphene oxide using ferrocene and HNO3 is reported. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) studies show increased number of sp2 domains in the rGO. The rGO shows specific surface area of ∼369 m2 g−1 and is stable till 700 °C. The measured specific capacitance of rGO is 106.5 F/g ensures that the rGO is promising material for electrochemical double layer capacitors. The magnetic hysteresis loop of rGO reveals diamagnetic behavior. The reduction mechanism for the synthesis of rGO using ferrocene and HNO3 has been proposed. We hope this approach might facilitate scalable production of high-quality rGO sheets which could lead to future industrial graphene based devices for various applications.

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