85 research outputs found
Micron Diamond Processing of Advanced Ceramics
Grinding is one of the most complex manufacturing processes in industry and understanding its physics is difficult due to the stochastic nature of the process. In this thesis, the influence of the abrasive grit’s shape and size on the grinding process is considered. A number of parameters are investigated to set a classification of the abrasives based on the grit’s shape and size. These parameters are determined according to image analyses of a large number of abrasive grits. Based on this investigation, the shapes of the abrasive grits could be classified into 21 groups. Typical grit shapes will fall into only few categories dominating the shape population. These dominant shapes are ellipsoid, sphere, quadrilateral frustrum, quadrilateral pyramid and tetrahedron pyramid. After the abrasives are assessed, a test rig for multiple grit scratching and wire saw cutting rig were developped and a series of multiple grit grinding tests are performed. For this purpose, series of scratching tests have been conducted with five different diamond abrasives. The cutting forces and the acoustic emission were used to characterize the grinding mechanism during this experiment. The machining performances of the abrasive grits are evaluated in consideration of the effect of different grit shapes on the grinding process outputs including force and acoustic emission. The experimental results show a high influence of the proportion of different grit shapes on grinding force: abrasive grits with rounded shape imply high cutting forces, while grits with pyramidal shape generate low cutting forces. Furthermore, based on the proportion of the dominant shapes in an abrasive sample a force model of the cutting force and the shape proportion of the abrasives was established. The force model and the experimental results emphasised the importance of taking into consideration the abrasive’s shape as a significant parameter that influences the grinding process. The online grinding surface creation monitoring was carried out by processing the acoustic emission signals. The acoustic emission signals are analysed in both the time and frequency domains. The results show that the signal feature extraction in the frequency domain gives excellent indication in correlation to the surface creation with different abrasive geometrical characteristics
Професійна технічна термінологія у галузі машинобудування
Рецензенти:
Д. В. Криворучко – доктор технічних наук, доцент, професор кафедри технології машинобудування, верстатів та інструментів Сумського державного університету;
В. І. Шатоха – доктор технічних наук, професор, проректор із науково-педагогічної роботи Національної металургійної академії України.Навчальний посібник є важливою формою міждисциплінарної та міжвузівської інтеграції, створений для зацікавлення студентів у якісному та поглибленому вивченні спеціальних дисциплін та професійної англійської мови, розвитку вмінь самостійної роботи і навичок при написанні та оформленні науково-дослідних робіт, активізації пізнавальної й дослідницької діяльності, стимулює наукові пошуки, обмін досвідом засобами англійської мови у галузі машинобудування.
Навчальний посібник призначений для інженерно-технічних і науково-педагогічних працівників, аспірантів і студентів інженерних спеціальностей вищих навчальних закладів.Розроблено в рамках виконання проекту Темпус «Модернізація вищої інженерної освіти в Грузії, Україні та Узбекистані відповідно до технологічних викликів» (ENGITEC 530244-TEMPUS-1-2012-1-SE-TEMPUS-JPCR
Професійна технічна термінологія у галузі машинобудування
Рецензенти:
Д. В. Криворучко – доктор технічних наук, доцент, професор кафедри технології машинобудування, верстатів та інструментів Сумського державного університету;
В. І. Шатоха – доктор технічних наук, професор, проректор із науково-педагогічної роботи Національної металургійної академії України.Навчальний посібник є важливою формою міждисциплінарної та міжвузівської інтеграції, створений для зацікавлення студентів у якісному та поглибленому вивченні спеціальних дисциплін та професійної англійської мови, розвитку вмінь самостійної роботи і навичок при написанні та оформленні науково-дослідних робіт, активізації пізнавальної й дослідницької діяльності, стимулює наукові пошуки, обмін досвідом засобами англійської мови у галузі машинобудування.
Навчальний посібник призначений для інженерно-технічних і науково-педагогічних працівників, аспірантів і студентів інженерних спеціальностей вищих навчальних закладів.Розроблено в рамках виконання проекту Темпус «Модернізація вищої інженерної освіти в Грузії, Україні та Узбекистані відповідно до технологічних викликів» (ENGITEC 530244-TEMPUS-1-2012-1-SE-TEMPUS-JPCR
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Finding the edge: Net-shape surface sculpting during cold spray deposition
This thesis provides an overview of how a successful method for structuring cold spray deposition was developed, allowing the creation of defined surfaces from a previously uncontrolled deposition profile.
When considering both additive and traditional manufacturing techniques, there remains a gap in the market for a high build rate, low-cost manufacturing system, capable of building net shape structures with good material properties from a range of difficult to work with engineering materials. A cold spray system had the potential to meet these requirements, and to provide additional benefits from being a solid-state fusion process, but the technique lacked the structural control capabilities required.
The aim of this body of work was to develop methods for controlling the shape of depositing material, allowing the creation of three-dimensional structures, and determining an approach which would allow the creation of flexible manufacturing platform. A limited number of attempts had been previously made to control the deposition shape. These methods met with limited success, did not offer real control over the shape of the deposit during operation, and presented issues of accuracy, reliability, and repeatability.
In this work, a series of concepts for shaping the deposition of the material were tested for the creation of flat vertical surfaces. Copper was used as the deposition powder as it readily deposits with cold spray under easily manageable conditions. The samples were investigated for shape conformity, surface roughness, porosity and build height, using optical microscopy and a white light interferometer. Successful shaping was delivered using masks, wide flow impeding backstops and thinner flow separating tools, provided the non-adhering powder had sufficient room to be cleared from the deposition zone. The thinner tool was further developed, as it allowed better positioning in smaller spaces for future systems.
Computational fluid dynamics models were created to assist with the understanding of some inconsistencies in deposit quality. The results of these simulations showed minimal alteration to the particle trajectory was caused by the alteration of gas dynamics from the introduction of obstacles.
The developed thin tool deposition concept was then successfully tested for robustness with deposition of further materials, and with the inclusion of laser irradiation of the substrate. It was demonstrated that the density, deposition efficiency and build heights are comparable with those expected from typical cold spray/supersonic laser deposition deposits. Following this, a range of building block structures were created, to further advance the shaping capabilities of the system, and demonstrate the freedom of deposition profile. Flat surfaces, thin walls, corners, curves, rings and overhangs were all shown to build efficiently without further complication.
It is concluded that it is both possible to control the shape of the depositing material during cold spray, and possible to do so without adversely affecting the deposit characteristics that give cold spray manufacturing its specific advantages over other manufacturing methods.
The next steps for this process are to create a more flexible system, automating the placement of the shaping tool and using a 5 or 6 axis bed and nozzle positioning setup. Further to that, precise control over the powder dosage, and the development of a known parameter space for select materials would progress the system to an additive capable platform
Aspheric geodesic lenses for an integrated optical spectrum analyser
Abstract available p. xiii-xi
Manufacturing of high precision mechanical components
The main goal of the thesis is to analyze key aspects of Precision Manufacturing, aiming at optimizing critical manufacturing processes: innovative experimental methodologies and advanced modelling techniques will be applied to cases study of industrial interest which have been successfully optimized
Corrosion and Degradation of Materials
Studies on the corrosion and degradation of materials play a decisive role in the novel design and development of corrosion-resistant materials, the selection of materials used in harsh environments in designed lifespans, the invention of corrosion control methods and procedures (e.g., coatings, inhibitors), and the safety assessment and prediction of materials (i.e., modelling). These studies cover a wide range of research fields, including the calculation of thermodynamics, the characterization of microstructures, the investigation of mechanical and corrosion properties, the creation of corrosion coatings or inhibitors, and the establishment of corrosion modelling. This Special Issue is devoted to these types of studies, which facilitate the understanding of the corrosion fundamentals of materials in service, the development of corrosion coatings or methods, improving their durability, and eventually decreasing corrosion loss
NASA technology utilization survey on composite materials
NASA and NASA-funded contractor contributions to the field of composite materials are surveyed. Existing and potential non-aerospace applications of the newer composite materials are emphasized. Economic factors for selection of a composite for a particular application are weight savings, performance (high strength, high elastic modulus, low coefficient of expansion, heat resistance, corrosion resistance,), longer service life, and reduced maintenance. Applications for composites in agriculture, chemical and petrochemical industries, construction, consumer goods, machinery, power generation and distribution, transportation, biomedicine, and safety are presented. With the continuing trend toward further cost reductions, composites warrant consideration in a wide range of non-aerospace applications. Composite materials discussed include filamentary reinforced materials, laminates, multiphase alloys, solid multiphase lubricants, and multiphase ceramics. New processes developed to aid in fabrication of composites are given
NASA Thesaurus. Volume 1: Hierarchical listing
There are 16,713 postable terms and 3,716 nonpostable terms approved for use in the NASA scientific and technical information system in the Hierarchical Listing of the NASA Thesaurus. The generic structure is presented for many terms. The broader term and narrower term relationships are shown in an indented fashion that illustrates the generic structure better than the more widely used BT and NT listings. Related terms are generously applied, thus enhancing the usefulness of the Hierarchical Listing. Greater access to the Hierarchical Listing may be achieved with the collateral use of Volume 2 - Access Vocabulary
NASA thesaurus. Volume 1: Hierarchical Listing
There are over 17,000 postable terms and nearly 4,000 nonpostable terms approved for use in the NASA scientific and technical information system in the Hierarchical Listing of the NASA Thesaurus. The generic structure is presented for many terms. The broader term and narrower term relationships are shown in an indented fashion that illustrates the generic structure better than the more widely used BT and NT listings. Related terms are generously applied, thus enhancing the usefulness of the Hierarchical Listing. Greater access to the Hierarchical Listing may be achieved with the collateral use of Volume 2 - Access Vocabulary and Volume 3 - Definitions
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