Showing papers in "International Journal of Precision Engineering and Manufacturing-Green Technology in 2018"
TL;DR: In this article, the processing characteristics of different vegetable oil-based nanofluid MQL for grinding various workpiece materials were evaluated in terms of force ratio, specific grinding energy, and G ratio.
Abstract: Minimum quantity lubrication (MQL) is an efficient, green, and eco-friendly method of applying cutting fluids in machining processes. This study presents the processing characteristics of different vegetable oil-based nanofluid MQL for grinding various workpiece materials. The performance of three lubricant types (i.e., pure palm oil, MoS2 nanofluid, and Al2O3 nanofluid) of good lubrication performance and three types of materials (i.e., Inconel 718, ductile cast iron, and AISI 1045 steel) was evaluated in terms of force ratio, specific grinding energy, and G ratio. The optimal processing combination of lubricants and workpiece materials under the same experimental conditions was obtained using orthogonal experiment. Optimization results were verified by evaluating the morphology of the workpiece surface and grinding debris. Experimental results show the different processing characteristics of materials when various workpieces are processed using dissimilar MQL lubricants. MoS2 nanofluid MQL is suitable for machining soft medium carbon steels, such as 45 steel, while Al2O3 nanofluid is suitable for machining materials of high strength and hardness, such as nickel-based alloys.
239 citations
TL;DR: In this article, the optical fiber sensors employed in environmental monitoring are summarized for understanding of their sensing principles and fabrication processes, followed by discussion on the potentials of OFS in manufacturing.
Abstract: Environmental monitoring has become essential in order to deal with environmental resources efficiently and safely in the realm of green technology. Environmental monitoring sensors are required for detection of environmental changes in industrial facilities under harsh conditions, (e.g. underground or subsea pipelines) in both the temporal and spatial domains. The utilization of optical fiber sensors is a promising scheme for environmental monitoring of this kind, owing to advantages including resistance to electromagnetic interference, durability under extreme temperatures and pressures, high transmission rate, light weight, small size, and flexibility. In this paper, the optical fiber sensors employed in environmental monitoring are summarized for understanding of their sensing principles and fabrication processes. Numerous specific applications in petroleum engineering, civil engineering, and agricultural engineering are explored, followed by discussion on the potentials of OFS in manufacturing.
236 citations
TL;DR: This paper reviews and summarizes machining processes using machine learning algorithms and suggests a perspective on the machining industry.
Abstract: The Fourth Industrial Revolution incorporates the digital revolution into the physical world, creating a new direction in a number of fields, including artificial intelligence, quantum computing, nanotechnology, biotechnology, robotics, 3D printing, autonomous vehicles, and the Internet of Things. The artificial intelligence field has encountered a turning point mainly due to advancements in machine learning, which allows machines to learn, improve, and perform a specific task through data without being explicitly programmed. Machine learning can be utilized with machining processes to improve product quality levels and productivity rates, to monitor the health of systems, and to optimize design and process parameters. This is known as smart machining, referring to a new machining paradigm in which machine tools are fully connected through a cyber-physical system. This paper reviews and summarizes machining processes using machine learning algorithms and suggests a perspective on the machining industry.
184 citations
TL;DR: In this article, a comparison of the concepts "Industrie 4.0" and "Made in China 2025" in the context of Small and Medium-sized Enterprises (SMEs) is presented.
Abstract: The Industrial Internet of Things (IIoT) confronts industrial manufactures with economic, ecological, as well as social benefits and challenges, referring to the Triple Bottom Line of sustainability. So far, research has mainly investigated its dimensions in isolation or economic aspects have not been compared with ecological and social perspectives. Further, research misses studies that are devoted to the special characteristics and requirements of Small and Medium-sized Enterprises (SMEs). This study aims to contribute to close this research gap, providing a research context that encompasses all three dimensions of sustainability. The results are based on data obtained from 329 SMEs, 222 in Germany and 107 in China, therefore allowing for a comparison of the concepts “Industrie 4.0” and “Made in China 2025” in the context of SMEs. In general, German SMEs expect a lower impact through “Industrie 4.0”, perceiving the concept as more beneficial for larger enterprises. We further find that Chinese SMEs foremost see social benefits. Challenges whilst introducing “Industrie 4.0”by German SMEs as well as several frame conditions are perceived more relevant than for “Made in China 2025”, as seen by Chinese SMEs. The paper closes with implications for research and practice based on these findings.
172 citations
TL;DR: This paper presents review of high precision reducers (HPRs) for industrial robots driving 4th industrial revolution, and provides HPRs market along with industrial robots, and principle, characteristics, and three main performances of H PRs are discussed.
Abstract: New industrial revolution - “The 4th industrial revolution” must be a remarkable milestone for the second decade of the twenty-first century. Many countries are competing to innovate their manufacturing chains for eco-friendly and energy-efficient productions. Although this green or sustainable manufacturing system evolves under the support of cyber-physical system (or digital twin) based on ICT technology, industrial robots also play important roles in this speedy, flexible and effective manufacturing chains. Recently, low-cost industrial robots or collaborative robots, are rising in a highly interactive environment with humans. Although an industrial robot consists of many important components such as mechanical parts (kinematic structure and reducer) and electric parts (servo motor, driver, sensors, and controller), precision reducer takes approximately 25% of material-cost and governs important performance indices of industrial robots. This paper presents review of high precision reducers (HPRs) for industrial robots driving 4th industrial revolution. First, we provide HPRs market along with industrial robots. According to previous studies, HPRs for industrial robots can be classified based on their principles: planetary reducer, cycloid reducer, and harmonic drive (HD). Then, principle, characteristics, and three main performances (hysteresis, rotational transmission error (RTE) and efficiency) of HPRs are discussed. In addition, compensation methods overcoming accuracy limits of HPRs are summarized. Finally, other applications of HPRs except industrial robots are presented.
107 citations
TL;DR: In this article, the impact of energy density on the porosity was analyzed with the data from experiments and existing works, and an effective energy-optimal (E2O) zone was proposed, where a relationship between energy density and porosity were developed.
Abstract: Selective laser melting (SLM) is one of the most widely used metal additive manufacturing technologies in producing high density parts. Energy density, a key-parameter combination, has been recognized to have a relationship with part formation, but such a relationship is extremely complex. This work aims to investigate energy density as a measure to evaluate energy demand in fabricating pore-free 316L stainless steel SLM parts. Key parameters in energy density were considered in the developed energy demand model. The impact of energy density on the porosity was analyzed with the data from experiments and existing works. Either low or high energy density can result in larger and more pore formation, and the influencing parameter was laser power, followed by layer thickness, scan speed, and hatch space. An effective energy-optimal (E2O) zone was proposed, where a relationship between energy density and porosity was developed. It is suggested that high laser power with high scan speeds can deliver energy to a thicker layer with relatively stable melt pool, fabricating high density parts. Hatch space can be decided accordingly to actual melt pool formation. This combination can effectively reduce energy density, and corresponding energy demand.
92 citations
TL;DR: In this article, the fabricating processes of both the electrolyte and the electrode via chemical vapor deposition and physical vapor depositions are discussed, and two platforms for designing TF-SOFCs are described: porous substrate and free-standing structures.
Abstract: Thin film solid oxide fuel cells (TF-SOFCs) are one of the promising portable power sources in terms of rapid on/off, compact system volume, and high power density. This paper reviews fabrications, and designs of TF-SOFCs operating the temperature range of 300-500°C. The fabricating processes of both the electrolyte and the electrode via chemical vapor depositions and physical vapor depositions are discussed. The two platforms for designing TF-SOFCs are described: porous substrate and free-standing structures.
52 citations
TL;DR: In this paper, the experimental characterization on micro-drilling process of titanium alloy (Ti-6Al-4V), which is one of representative difficult-to-cut materials, with the nanofluid minimum quantity lubrication (nMQL) was discussed.
Abstract: This paper discusses the experimental characterization on micro-drilling process of titanium alloy (Ti-6Al-4V), which is one of representative difficult-to-cut materials, with the nanofluid minimum quantity lubrication (nMQL). The miniaturized machine tool system is set up, and then, a series of micro-drilling experiments are performed under compressed air (CA), pure MQL and nMQL for a comparison. For the nanofluid, nanodiamond particles with the sizes of 35 nm and 80 nm are chosen, and the base fluid is vegetable oil. For the micro-drilling process, an uncoated carbide twist drill having the diameter of 300 μm is used for drilling holes in the titanium alloy workpiece. The experimental results show that the nMQL can reduce the drilling torques and thrust forces, but its effect is more obvious at a low feed rate (10 mm/min). In addition, the edge corner radii and hole circularity errors are significantly reduced in the case of small size (35 nm) and high weight concentration (0.4 wt. %) of the nanodiamond particles at the low feed rate. It is also found that the nMQL effectively mitigates chip adhesion of drill tool and burr of drilled holes.
50 citations
TL;DR: In this article, the authors explored the use of ecofriendly fiber surface treatment in order to limit the environmental hazards of conventionally used chemical treatments by using an aqueous solution of sodium bicarbonate (10% (w: v)).
Abstract: Green Composites (Biocomposites) comprising of lignocellulosic fibers are low cost sustainable materials having huge potential to replace petroleum derived commodity and engineering plastics. In order to improve the interfacial interaction with the matrix, lignocellulosic fibers are subjected to fiber surface modification. The present research endeavor aims to explore the use of ecofriendly fiber surface treatment in order to limit the environmental hazards of conventionally used chemical treatments. Fiber surface modification of Aloe Vera fibers prior to their incorporation into PLA based biocomposites was done using an aqueous solution of sodium bicarbonate (10% (w: v)). FTIR spectroscopy, thermal analysis, lignocellulosic composition, single fiber strength and fiber morphology were examined to ascertain the effect of varying treatment time (24, 48, 72, 120 and 168 hours) on the fiber characteristics. The biocomposite test specimens were developed using Extrusion-Injection molding process. An optimum fiber treatment time of 72 hours exhibited highest improvement in tensile, flexural and compressive behavior of the developed biocomposites. The biocomposites incorporating treated (72 hours) Aloe Vera fibers exhibited 104.9% higher impact strength as compared to neat PLA. Hence, the use of sodium bicarbonate treatment for lignocellulosic-fiber surface modification ensures greener and safer processing of biocomposites without compromising their mechanical properties.
49 citations
TL;DR: A framework was developed for giving a guideline for PHM application based on common core modules across manufacturing systems and their kinds with respect to the amount of available data and domain knowledge.
Abstract: Prognostics and health management (PHM) has emerged as an intelligent solution to improve the availability of manufacturing systems. PHM consists of system health monitoring, feature extraction, fault diagnosis, and fault prognosis through remaining useful life estimation. However, the application of PHM to manufacturing systems is challenging because systems have become more complex and uncertain. In particular, small and medium-sized enterprises have difficulty in applying PHM due to the lack of internal expertise, time and resources for research and development. The objective of this paper is to develop a framework to provide a readily usable and accessible guideline for PHM application to manufacturing systems. A survey was performed to gather the current practices in dealing with system failures and maintenance strategies in the field. A framework was developed for giving a guideline for PHM application based on common core modules across manufacturing systems and their kinds with respect to the amount of available data and domain knowledge. A reference table was developed to track the PHM techniques for feature extraction, fault diagnosis, and fault prognosis. Finally, fault prognosis of a system was conducted as a case study, following the framework and the reference table to verify its practical use.
43 citations
TL;DR: In this paper, the authors used Quality Function Deployment for Environment (QFDE) technique to select thermoplastic polymers to be used in natural fiber-reinforced polymer composite for automotive anti-roll bar.
Abstract: In this study, selection of thermoplastic polymers to be used in natural fibre-reinforced polymer composite is performed using Quality Function Deployment for Environment technique. The candidate materials for the matrix in composites are thermoplastic polyurethane, highdensity polyethylene, low-density polyethylene, polystyrene and polypropylene and the selection process is carried out based on the design requirements of an automotive anti-roll bar. Requirements are collected through a study on the voice of customers and the voice of the environment. The approach is followed by sensitivity analysis using Expert Choice software based on the Analytic Hierarchy Process method. From the analysis, high-density polyethylene scored the highest (28.76%), and followed by thermoplastic polyurethane, which had 22.30% of the overall score. Finally, Young’s modulus of hemp fibre reinforced high-density polyethylene and thermoplastic polyurethane composites were compared, predicted using the Halpin-Tsai method. The results show that hemp-reinforced thermoplastic polyurethane composite shows higher Young’s modulus of 10.6 GPa, compared with hemp-reinforced high-density polyethylene composite (8.27 GPa). Based on these two analyses, thermoplastic polyurethane is selected as the most suitable polymer matrix for natural fibre composites for automotive anti-roll bar.
TL;DR: In this paper, the effect of the above parameters on the cutting performance of EMQL turning stainless steels in comparison with completely dry and conventional wet and MQL cutting was investigated.
Abstract: A cost-effective and eco-friendly alternative to conventional flood cooling-lubrication and minimum quantity lubrication (MQL) is electrostatic minimum quantity lubrication (EMQL). EMQL, which is a novel green machining technology that utilizes the synergetic effects between electrostatic spraying (ES) and MQL, has been successfully shown a potential in milling process. However, the effective application of EMQL is not only connected with machining parameters, such as cutting speed and feed rate, but also related to oil mist parameters including charging voltage, lubricant flow rate, air pressure, and nozzle position and distance. This paper investigated the effect of the above parameters on the cutting performance of EMQL turning stainless steels in comparison with completely dry and conventional wet and MQL cutting. The results suggested that cutting speed and voltage were important factors affecting the effectiveness of EMQL, and found that there were the optimum air pressure and nozzle position and distance when EMQL turning AISI 304 stainless steel. Properly selecting these parameters, a viable alternative to wet and MQL cutting could be achieved by promoting lubricants into cutting interface to reduce friction and adhesion of work-piece materials on the interface.
TL;DR: In this paper, an energy consumption model was created that accounted for the energy consumption during primary metal production, deposition, and machining phases of wire-based and powder-based additive-subtractive manufacturing processes.
Abstract: There has been a growing trend in industry towards the development of integrated manufacturing centers that combine several manufacturing processes, such as the mill-turn center. As additive manufacturing becomes a more widely adopted technology, combining additive with subtractive manufacturing in one machine is a logical evolution to provide the benefits of final parts made from raw materials with the dimensional tolerance and surface finish expected in many applications. An energy consumption model was created that accounted for the energy consumption during primary metal production, deposition, and machining phases of wire-based and powder-based additive-subtractive manufacturing processes. This model was applied to a case study where the energy consumption to produce sub-sized, sheet type, and plate type (size) tensile bars was calculated. It was found that the wire-based process consumed less energy during deposition, whereas powder-based was less energy consumptive during primary metal production and machining. The findings suggest that given the present understanding of the respective technologies’ capabilities, the desired final net shape will dictate the preferred manufacturing process with respect to energy consumption considerations.
TL;DR: In this article, the authors used Rongalite as a reducing agent via solution process to reduce copper salt within 10-20 min at low temperature without using any complexing agent.
Abstract: Copper nanoparticles (Cu-Nps) are one of the promising material for the advancement of nanoscience and technology. In this work, we successfully synthesized Cu-Nps using sodium hydroxymethanesulinate (Rongalite) as a novel reducing agent via solution process. Cu-Nps were achieved from chemical reduction of copper salt within 10-20 min at low temperature without using any complexing agent. In order to investigate the phase, size, and composition of the synthesized Cu-Nps, X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were employed. Average particle size of the synthesized Cu-Nps is 152 nm. It is expected that the outcomes of this study take a step closer towards designing general strategies for a simple, environment friendly and low cost synthesis method of Cu-Nps. The synthesized Cu-Nps are mixed with commercial Cu-Nps and sintered using photonic sintering process. To determine the optimum sintering energy, the flash light irradiation energy was varied and optimized. An XRD and SEM were used to characterize the sintered Cu-Nps. The resulting sintered Cu-Nps exhibited a low resistivity (20.73 μΩcm) without any damages of the polymer substrate.
TL;DR: A data-driven FDM process monitoring and diagnosis system is developed by using two types of sensors – an accelerometer and an acoustic emission (AE) sensor.
Abstract: Fused deposition modeling (FDM), one of representative additive manufacturing (AM) technologies, has been widely used for fabricating functional parts with geometrical complexity. However, it has suffered from degraded part quality and low process reliability and controllability. Therefore, it is of much significance to develop a monitoring and diagnosis system for the FDM process to overcome such drawbacks. In this paper, a data-driven FDM process monitoring and diagnosis system is developed by using two types of sensors – an accelerometer and an acoustic emission (AE) sensor. A large number of experimental data, collected from the accelerometers and AE sensor under healthy and faulty process states, are processed to obtain a critical feature – a root mean square (RMS). The RMS values are then used for training the FDM process monitoring and diagnosis models based on a support vector machine (SVM) algorithm and a k-fold cross validation approach. In particular, the SVM-based models for the odd- and evennumbered layers of one FDM specimen are developed. For a real-time validation in a factory floor, the non-linear SVM-based models using the acceleration signals are used for the software development. The diagnosis accuracy is better than 87.5%, and an applicability of the models is verified.
TL;DR: In this article, Bi-Grid, TriGrid, Quadri-Grid and Kagome-Grid honeycombs were designed and fabricated using 3D printing technology Sandwich composites were prepared by gluing the cores and composite face sheets together.
Abstract: In this study, Bi-Grid, Tri-Grid, Quadri-Grid and Kagome-Grid honeycombs were designed and fabricated using 3D printing technology Sandwich composites were prepared by gluing the cores and composite face sheets together. Mechanical performance of the sandwich structures were characterized using finite element analysis and three-point bending test. Results indicate that when suffering from bending loads, the stress concentrations are located at the loading zone on upper face sheets (distributed in both sides of the indenter) and supporting zone on bottom face sheets, and the stress concentration zones of the honeycomb cores are located in the area that between indenter and supports. The failure mechanism of the Bi-Grid sandwich structure is interfacial de-bonding between composite face sheet and Bi-Grid core, and the failure modes of the Tri-Grid, Quadri-Grid and Kagome-Grid are core shear. The mechanical performance of Quadri-Grid sandwich structure is better than that of the other three structures.
TL;DR: In this article, the authors review recent progress in eco-friendly colloidal quantum dot photovoltaics, with a focus on two aspects: 1) the non-toxic or lesstoxic quantum dot materials designed for efficient thin-film based solar cells by considering factors such as bandgap tunability, exciton binding energy, and more.
Abstract: Power conversion efficiencies of colloidal quantum dot solar cells, which have focused mainly on lead chalcogenide systems until recently, have increased rapidly and currently exceed 12%. Among the many issues involved in commercialization of this technology as a consumer product, lead-based materials in these systems must be replaced. This requires the use of a low-cost, low-loss, and non-toxic chemical, along with the development of an eco-friendly manufacturing process. Herein, we review recent progress in ecofriendly colloidal quantum dot photovoltaics, with a focus on two aspects. First, we examine non-toxic or less-toxic quantum dot materials designed for efficient thin-film based solar cells by considering factors such as bandgap tunability, exciton binding energy, and more. We then present the performance of quantum dot solar cells using these green quantum dot materials, and discuss the scientific and technological issues facing them. Second, we review fabrication methods of quantum dot thin films with low-cost, lowwaste, and non-toxic chemicals, for use in eco-friendly manufacturing processes.
TL;DR: In this article, the authors provide a general understanding of the joining or in-situ fabrication of metal matrix composites using solid-state friction stirring and provide a brief introduction into recent efforts that have been used to fabricate MMCs by FSW.
Abstract: Herein, friction stir welding (FSW) of metal matrix composites (MMCs) with different combinations of the reinforcement and the metal matrix is highlighted with a brief introduction into recent efforts that have been used to fabricate MMCs by FSW. As a solid state joining technique, FSW consumes significantly lower energy than conventional fusion welding processes. In addition to properly selecting the process parameters, the mechanical properties of the FSW joints of MMCs are closely related with the refinement and homogeneous distribution of reinforcements in the stir zone. The fatigue and fracture properties of MMCs may be enhanced or aggravated by FSW, depending on the combination of the reinforcement and the metal matrix. For FSW of MMCs, the selection of the tool material can also be a critical issue; the presence of hard reinforcements may increase the rate of tool wear. Macro-and microstructural phenomena for MMCs during FSW depend on the material flow due to plasticization and the behavior of the reinforcements. Even though FSW are generally expected to induce a homogeneous distribution of reinforcements in the stir zone (SZ), it can be difficult to obtain a homogeneous distribution of reinforcements in the SZ depending on the combination of the reinforcement and the metal matrix. The existence of reinforcements naturally affects the microstructure of the joint and can even induce the formation of intermetallics/complex phases in the joint. This review provides a general understanding of the joining or in-situ fabrication of MMCs using solid-state friction stirring.
TL;DR: In this article, the concave micro-grooves texture (MGT) and convex volcano-like texture (VLT) were fabricated separately on lathe tools' rake faces by laser surface texturing (LST).
Abstract: Tool-chip adhesion impacts on cutting performance significantly, especially in finish cutting process. To promote cutting tools’ anti-adhesion property, the concave micro-grooves texture (MGT) and convex volcano-like texture (VLT) were fabricated separately on lathe tools’ rake faces by laser surface texturing (LST). Various orientations of MGT and different area densities (9% and 48%) and regions (partial and full) of VLT were considered in textured patterns designing. The following orthogonal cutting experiments, machining of aluminum alloy 5038, analyzed tools’ performances including cutting force, cutting stability, chip shape, rake face adhesion and abrasion. It indicated that under dry finish cutting conditions, MGT contributed to cutting stability and low cutting forces, meanwhile friction and normal force reduced by around 15% and 10%, respectively with a weak correlation to the grooves’ orientation. High density VLT tools, on the other hand, presented an obvious anti-adhesion property. A 5 μm reduction of crater wear’s depth can be observed on textured rake faces after long length cutting and textured rake faces presented half size of BUE regions comparing to the flat tool, however, once the texture morphologies were filled or worn, the anti-adhesion effect could be invalid. The bearing ratio curve was employed to analysis tool-chip contact and durability of textured surfaces contributing to a better understanding of anti-adhesion and enhanced durability of the textured tools.
TL;DR: In this paper, a laser-assisted trochoidal milling process was developed for Ti-6Al-4V alloys, where the material is locally preheated by a laser heat source prior to machining by the cutting tool.
Abstract: Titanium alloys are widely used in high value-added applications such as aerospace and automobile products. However, their superior mechanical properties also make them difficult-to-cut materials. Various machining methods have been developed for machining difficult-to-cut materials. One of these methods, the trochoidal milling method, combines a linear tool movement with a circular movement. It has several advantages, including low cutting force and better tool life, and it can also be applied to high speed machining. Laser-assisted machining (LAM) is another hybrid machining method for difficult-to-cut materials. When the material is locally preheated by a laser heat source prior to machining by the cutting tool, cutting resistance is reduced, and processing efficiency is increased. The purpose of this study is to develop a laser-assisted trochoidal milling process by combining the two machining methods. The processing efficiency of the trochoidal milling method was verified through experiments and comparison with conventional milling. Also, the cutting force and energy efficiency by considering specific cutting energy during the laser-assisted trochoidal milling of Ti-6Al-4V were analyzed for various machining conditions and compared with trochoidal milling.
TL;DR: An attempt was made to develop a relatively precise and direct power consumption model to help researchers make power optimization much easier and more practical than before.
Abstract: Nowadays soaring energy price, increasing environmental concerns, and stringent legislations make energy saving very emergency and helpful both for enterprises and environment. To deal with these issues, this paper presents a generalized mathematical power prediction model of face milling process used in manufacturing. An attempt was made to develop a relatively precise and direct power consumption model to help researchers make power optimization much easier and more practical than before. First, an infinitesimal cutting force model was proposed based on theoretical and experimental foundations. Secondly, relationship between power consumption and cutting force components was revealed, and power consumption based on infinitesimal cutting forces during metal removal process was developed. Finally, the proposed model was experimentally verified by comparing predicted and measured power consumption. Both average and instantaneous values of power consumption were used to analyze prediction error of the model. This proposed model can be used to evaluate and optimize cutting power consumption once cutting parameters were decided based on minimal energy demand. Results showed that the mean errors of maximum power and mean power were 0.076% and 0.208%, respectively. Otherwise, this proposed model will drive the field of power consumption simulation development.
TL;DR: Two DPPT control algorithms with a mode switch integrated into the conventional control algorithm were found to work well with the basic wind turbine power control algorithm and showed better performance in terms of loading.
Abstract: Simple demanded power point tracking (DPPT) control algorithms with a mode switch are proposed and experimentally validated in this study. One is a torque-based control and uses the generator torque with fixed blade-pitch angle. The other is blade-pitch based and uses both the generator torque and blade pitch for DPPT control. Both control algorithms receive power demand from a higherlevel controller and use their control strategies to track it. The two DPPT control algorithms were integrated with the basic torque and pitch control algorithms, and simulations using an in-house code and a high fidelity multi-body dynamic aeroelastic code were performed for steady and dynamic conditions. To verify the algorithms experimentally, wind tunnel tests with a scaled wind turbine having active pitch control capability were performed. From the simulation and the test, the proposed DPPT algorithms integrated into the conventional control algorithm were found to work well with the basic wind turbine power control algorithm. The torquebased control showed better performance in terms of power tracking, but the pitch-based control showed better performance in terms of loading.
TL;DR: It can be concluded from the results that the optimum design of the proposed OBEH sidewalk block enables useful power generation while satisfying the target reliability of fatigue failure in the presence of the inherent randomness.
Abstract: Energy harvesting, which converts ambient, otherwise wasted, energy sources into usable electricity, is expected to contribute to the formulation of a self-generating power grid. This type of grid can enable sustainable operation of wireless sensor networks as the “Smart City” vision becomes reality. Human walking is a plentiful mechanical energy source wasted during daily activities. This study aims to develop an omnidirectional biomechanical energy harvesting (OBEH) sidewalk block that is able to generate electricity from human walking. Here, a systematic design framework for the OBEH sidewalk block is presented; it consists of three important ingredients, specifically: (1) extraction of a footstep loading profile from human gait analysis; (2) electroelastically coupled finite element modeling to estimate the transient output responses under the footstep loading profile; and (3) reliability-based design optimization of the OBEH sidewalk block. This study considers two kinds of the inherent randomness, including (1) variability in the material properties and geometry; and (2) uncertainty in the position and direction of the footsteps. It can be concluded from the results that the optimum design of the proposed OBEH sidewalk block enables useful power generation while satisfying the target reliability of fatigue failure in the presence of the inherent randomness.
TL;DR: In this article, the relationship between the static mechanical properties of Ti-6Al-4V manufactured through selective laser melting (SLM) and post-process heat treatments, namely stress relieve, annealing and hot isostatic pressing (HIP), was investigated.
Abstract: This work investigates the relationships between the static mechanical properties of Ti-6Al-4V manufactured through selective laser melting (SLM) and post-process heat treatments, namely stress relieve, annealing and hot isostatic pressing (HIP). In particular, Ti-6Al-4V parts were fabricated in three different build orientations of X, Z, and 45° to investigate the multi-directional mechanical properties. The results showed that fully densified Ti-6Al-4V parts with densities of up to 99.5% were obtained with optimized SLM parameters. The microstructure of stress relieved and mill annealed samples was dominated by fine α′ martensitic needles. After HIP treatment, the martensite structure was fully transformed into α and β phases (α+β lamellar). Within the realm of tensile properties, the yield and ultimate strength values were found statistically similar with respect to the built orientation for a given heat treatment. However, the ductility was found orientation dependent for the HIP samples, where a lower value was observed for samples built in the X direction.
TL;DR: In this article, a laser-assisted fillet milling process was developed for machining 3D shapes, and the effective depth of cut (EDOC) was obtained using thermal analysis.
Abstract: Laser-assisted machining (LAM) is known to be an effective and economical technique for improving the machinability of difficult-to-machine materials. In the LAM method, material is preheated using a laser heat source and then the preheated area is removed by following cutting tool. For laser-assisted turning (LAT), the configuration of the system is not complicated because laser irradiates from a fixed position. In contrast, laser-assisted milling (LAMill) system is not only complicated but also difficult to control because laser heat source must always move ahead of the cutting tool along a three dimensional (3D) tool path. LAMill is still early stage and cannot yet be used to machine finished products with 3D shapes. In this study, a laser-assisted fillet milling process was developed for machining 3D shapes. There are no prior studies combining fillet milling and LAMill. Laser-assisted fillet milling strategy was proposed, and effective depth of cut (EDOC) was obtained using thermal analysis. Experiments were designed using response surface method and cutting force prediction equations were developed using statistical analysis and regression analysis. The optimum machining conditions were also proposed, and energy efficiency of the LAMill was analyzed by comparing the specific cutting energy of conventional machining (CM) and LAMill.
TL;DR: To develop a high performance and environmentally friendly trimming die using DED, evaluation of mechanical properties of material developed, stress analysis in shear work was evaluated and the commercial application of the developed technology was discussed.
Abstract: The manufacturing industry nowadays has a greater interest in reducing global warming and promoting energy-saving measures than ever before. This has led to the development of eco-friendly manufacturing systems to replace conventional ones. Additive manufacturing (AM) technology, for instance, is expected to contribute to reducing material costs and energy consumption. Unlike conventional material-cutting manufacturing processes, AM enables designs of any shape in manufacturing by adding the necessary parts layer by layer. Direct energy deposition (DED) is one of the many AM technologies available for a variety of commercial steel powders such as P20, P21, SUS420, H13, D2 and other Non-ferrous metal powders. The DED is process that can be applied to various industries, like molding, medicine, and defense. Of these, its application to the molding industry is the most practical, since the process can be used to deposit different materials on existing parts. Using this technology, it becomes possible to manufacture high-functioning parts composed of various materials at reasonable cost. In this study, the DED is used to develop a high-performance and environmentally friendly trimming die. In this study, to develop a high performance and environmentally friendly trimming die using DED, evaluation of mechanical properties of material developed, stress analysis in shear work. The commercialization of the developed technology was evaluated and the commercial application of the developed technology was discussed.
TL;DR: In this article, a WS2 soft-coated micro-nano textured self-lubricating dry cutting tool (WTT tool) was developed and tested and the results show that the WTT tool has the best cutting performance among all the tools tested under the same cutting conditions.
Abstract: A new dry cutting tool named WS2 soft coated Micro-Nano textured self-lubricating dry cutting tool (WTT tool) is developed and tested. Dry turning tests have been carried out on 45# quenched and tempered steel with a WTT tool and three other types of alternative tools. The machining performance was assessed in terms of the cutting forces, cutting temperature, friction coefficient at the tool-chip interface, chip deformation, tool wear, and the surface roughness of the machined workpiece. The results show that the WTT tool has the best cutting performance among all the tools tested under the same cutting conditions. Through theoretical analysis and experimental results, the mechanisms of the WTT tool in improving cutting performance were put forward. Meanwhile, the effect of Micro-Nano texture and WS2 soft coating on the cutting forces and the cutting temperature is analyzed. It can be concluded that the WTT tool can effectively improve the anti-adhesion and wear-resistance properties and increase the tool life.
TL;DR: The working power of an engine excavator and the component sizing of a fuel cell-battery excavator is investigated and an operational strategy is suggested that suggests optimal capacities for both power sources and establishes a baseline for them.
Abstract: The powertrain of hybrid vehicles has been a major research issue due to the power distribution by the combination of mechanical energy. The power distribution of engines and motors have been determined by optimal control or rule-based control. However, the hybrid powertrain, which includes fuel cells, is a major research issue because the fuel cells and batteries support the motors. Recently, there have been many cases of using such fuel cell powertrains among construction machinery. In a fuel cell hybrid excavator, the fuel cell is responsible for most of the workload, and the battery supplement the fuel cell. Depending on the amount of battery support, the excavator can handle a larger workload; however, it is necessary to have an effective operating strategy that consider the battery state of charge (SOC). It is important to select the appropriate capacity for the fuel cell and battery. Therefore, this paper investigated the working power of an engine excavator and the component sizing of a fuel cell-battery excavator. The background control theory of component sizing is dynamic programming and this study suggests an operational strategy. It also suggests optimal capacities for both power sources and establishes a baseline for them.
TL;DR: In this study, an automatic design methodology for conformal lightweight structures was developed based on a three-dimensional (3D) tetrahedral mesh, and designed cellular structures showed high specific stiffness and strength, and could support 10000 times heavier load than their own weight.
Abstract: Recent developments of additive manufacturing (AM) have extended its application to the direct fabrication of functional parts. Owing to design flexibility and complexity, design for AM (DFAM) has received increasing attention as a new design method that can overcome traditional manufacturing constraints, and has been applied to multi-components integration, multi-material parts, and lightweight structures. In this study, an automatic design methodology for conformal lightweight structures was developed based on a three-dimensional (3D) tetrahedral mesh. A numerical algorithm was developed to generate lightweight cellular structures via the following steps: (i) definition of a target solid; (ii) discretization of the target volume using a tetrahedral mesh; (iii) construction of a number of struts along the edges of every tetrahedral element; (iv) Boolean operation to unify the generated struts; and (v) preparation of output files for 3D printing and finite element analysis (FEA). This algorithm was then applied to generate conformal cellular structures with various shapes. Effects of lattice design parameters on the relevant density change were discussed. The designed cellular structures were then fabricated by AM, and their mechanical properties were evaluated by compression tests. The fabricated lightweight structures showed high specific stiffness and strength, and could support 10000 times heavier load than their own weight.
TL;DR: In this paper, an analysis of the lateral thickness of a coated layer that consists of a fluid with a high viscosity produced by using a slot-die roll-to-roll system with specific attention focused on a pinned edge phenomenon exhibited in the coated layer is presented.
Abstract: Roll-to-roll slot-die manufacturing of soluble materials with a uniform layer is a critical step in realizing low-cost and eco-friendly printed electronics for solar cells and batteries. This study presents an analysis of the lateral thickness of a coated layer that consists of a fluid with a high viscosity produced by using a slot-die roll-to-roll system with specific attention focused on a pinned edge phenomenon exhibited in the coated layer. A solution viscosity of 832 mPa·s is used and includes relatively high capillary numbers in the experiment in the range of 0.47–3.47. The purpose of the study included analyzing various forces around the coating nozzle and determining the correlation between forces by using dimensionless numbers. Computational fluid dynamics analysis and experiments were performed to obtain various parameters in terms of these dimensionless numbers. The experimental results suggest that the pinned edge should be reduced below 10% by reducing the coating gap parameter that represents the gravity forces.