Dissertations / Theses on the topic 'Armour layer'

Mestrado em Engenharia Civil
Coastal erosion is a serious problem that affects numerous countries and particularly Portugal. The sediment deficit, increasing urbanistic pressure and highly energetic coastal areas anticipate the necessity of large investments in shore protection structures. The design process of coastal structures is mainly dependent on empirical formulations, followed by tests on physical models to validate the design solutions. In these empirical formulations, the incorporation of several parameters in to coefficients, adds a level of subjectivity that is relevant on the results. This document intends to address the subjectivity problem through the analysis of the stability coefficient in the Hudson formula. In the original formula, this coefficient expresses the influence of a certain amount of parameters on the armour layer stability of coastal structures. However, there is an absence of recommended values that take into account some important parameters. By increasing the knowledge over the several parameters that influence the stability coefficient, a better accuracy can be achieved. The main focus is on the parameters considered by the Van der Meer formulations (permeability, storm duration, damage level and slope angle) and on the incidence angle in which the wave attacks the structure. A sensitivity analysis was performed for various parameters, in order to evaluate the influence of each parameter on the stability coefficient and final stability values. Using two study cases, a comparison was performed on the design stability coefficient and the coefficient that resulted from physical tests.
A erosão costeira é um problema grave que afecta muitos países do mundo e em particular, Portugal. O défice sedimentar e a crescente pressão urbanística, aliadas a um regime costeiro energético, anteveem a necessidade de avultados investimentos em estruturas de proteção costeira. O processo de dimensionamento de estruturas costeiras passa pela utilização de formulações empíricas, seguido de testes em modelo físico para validar as soluções. Nestas formulações, a incorporação de diversos aspectos em coeficientes, adiciona um nível de subjetividade relevante aos resultados. A intenção deste trabalho é abordar o problema da subjetividade pela análise do coeficiente de estabilidade, presente na fórmula de Hudson. Na fórmula original, este coeficiente exprime a influência de um certo número de parâmetros na estabilidade do manto de proteção de estruturas costeiras. No entanto, existe uma ausência de valores recomendados que tenham em conta alguns parâmetros importantes. Ao amentar o conhecimento sobre os diversos parâmetros que influenciam o coeficiente de estabilidade, é possível alcançar uma maior precisão. De entre os parâmetros que influenciam a estabilidade, o foco principal da análise é sobre os parâmetros considerados nas fórmulas de Van der Meer (permeabilidade, duração da tempestade, nível de dano e ângulo do talude da estrutura) e no ângulo de incidência da onda sobre a estrutura. Uma análise de sensibilidade foi feita para avaliar a influência de cada parâmetro no valor do coeficiente de estabilidade e na estabilidade final. Usando dois casos de estudo, foi feita uma comparação do coeficiente de estabilidade obtido na fase de projeto e o coeficiente que resulta dos testes em modelo físico.

2012 - 2013
Le aree costiere rappresentano sistemi naturali del tutto unici, così come unici sono i fenomeni che le caratterizzano. L’erosione dei litorali, divenuta ormai un fenomeno di interesse planetario, ha spinto verso un approfondimento delle conoscenze dei processi costieri, consentendo di operare nella lotta ai suddetti fenomeni, attraverso strategie sempre più mirate e attente. Una migliore conoscenza dei processi costieri, infatti, può consentire agli ingegneri di adottare approcci più corretti nella progettazione di opere di protezione costiera. La principale fonte di supporto per l’ingegneria costiera è rappresentata dalla letteratura tecnica e scientifica relativa ad interventi già posti in essere nel passato. Strumenti di conoscenza aggiuntivi possono essere forniti da fonti di diversa natura. Uno su tutti la modellistica fisica, che rappresenta senza dubbio un importantissimo mezzo di conoscenza al servizio della progettazione del tipo di opere in parola. Tramite la modellistica fisica è possibile, ad esempio, studiare fenomeni quali la propagazione del moto ondoso nel suo percorso dal largo verso riva, l’agitazione ondosa all’interno dei porti, la stabilità delle strutture sottoposte alle azioni dinamiche del moto ondoso, così come il wave runup, l’overtopping, la riflessione e la trasmissione ad esse associati. Si tratta di fenomeni la cui conoscenza risulta di fondamentale importanza quando nasce l’esigenza di progettare un’opera di difesa costiera. E il risultato è tanto migliore, quanto più sono specifiche le conoscenze su cui viene fondato il progetto. Si consideri, ad esempio, il caso delle dighe a scogliera, il cui strato di armatura più classico è costituito da massi naturali di grandi dimensioni: laddove non ci dovesse essere sufficiente disponibilità del suddetto materiale, o laddove si sia in presenza di condizioni meteomarine particolarmente gravose, le unità di armatura in massi naturali vengono normalmente sostituite da unità in calcestruzzo, per le quali esiste ormai una gran varietà. E’ evidente che, a seconda della forma e delle dimensioni delle suddette unità, nonché del numero di strati con cui esse vengono posizionate sulla mantellata, cambia sensibilmente il comportamento idraulico della struttura. Ne consegue la necessità, in fase di progettazione, di poter disporre di parametri che siano caratteristici della tipologia di unità di armatura della mantellata che si deve realizzare. L’individuazione dei suddetti parametri deve essere necessariamente il risultato di prove sperimentali eseguite in laboratorio su modelli fisici di strutture realizzate con quelle specifiche unità di armatura. Oggetto del presente lavoro, dunque, è lo studio dei fenomeni che intervengono nell’interazione tra il moto ondoso e le strutture di difesa costiera, in particolare per un’opera a gettata costituita da una tipologia di unità di armatura in calcestruzzo non presente in mercato, attualmente sottoposta a procedura brevettuale. Il lavoro è stato condotto mediante sperimentazione su un modello fisico bidimensionale realizzato presso il Laboratorio di Ricerca e Sperimentazione per la Difesa delle Coste (LIC) del Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica (DICATECh) del Politecnico di Bari. Lo studio ha permesso di individuare alcuni parametri caratteristici delmasso in oggetto, quali ad esempio il coefficiente di stabilità e il coefficiente di scabrezza, necessari per il calcolo delle grandezze con cui poter effettuare il dimensionamento dell’opera. Inoltre, sono state valutate alcune delle formulazioni presenti in letteratura per il calcolo delle suddette grandezze, al fine di analizzare la loro adattabilità al nuovo masso. [a cura dell'autore]
XII n.s.

The incidence of fretting damage in the pressure armour wires of flexible pipes used in offshore oil explorations has been investigated. A novel experimental facility which is capable of simulating nub and valley contact conditions of interlocking wire winding with dynamic slip, representative of actual pipe loading, has been developed. The test set-up is equipped with a state of the art data acquisition system and a controller with transducers to measure and control the normal load, slip amplitude and friction force at the contact, in addition to the hoop stress in the wire. Tests were performed with selected loading and the fretted regions were examined using optical microscopy techniques. Results show that the magnitude of contact loading and the slip amplitude have a distinct influence on surface damage. Surface cracks originated from a fretting scar were observed at high contact loads in mixed slip sliding while surface damage predominantly due to wear was observed under gross slip. The position of surface cracks and the wear profile have been related to the contact pressure distribution. The evolution of friction force and surface damage under different slip and normal pressure conditions has been analysed. A fracture mechanics based numerical procedure has been developed to analyse the fretting damage behaviour. A severity parameter is proposed in order to ascertain whether the crack growth is in mode I or mode II cracking. The analysis show the influence of mode II cracking in the early stages of crack growth following which the crack deviates in the mode I direction making mode I the dominant crack propagation mechanism. The crack path determined by the numerical procedure correlates well with the experimental results. A numerical analysis was carried out for the fretting fatigue condition where a cyclic bulk stress superimposes with the friction force. The analysis correlates well with short crack growth behaviour. The analysis confirms that fretting is a significant factor that should be taken into account in design and operation of the pressure armour wires of flexible pipes at high contact pressure if the bulk cyclic load superimposes with the friction force. As predicted by the numerical procedure and further by experimental investigations, the surface cracks initiating on the wire in this condition are self arresting after propagating into a certain depth.

Flexible pipes are commonly used for connecting seabed flow-lines to floating production facilities. The general riser design consists of an internal carcass for collapse resistance, a polymer fluid barrier, carbon steel interlocked circumferential pressure armour layer for resisting internal pressure loads, helically wound carbon steel tensile armour layers to resist axial loads and a watertight external sheath. Much of the analytical work that has been carried out on flexible composite pipe is based on the early stress analyses of wire ropes, and this is primarily because of the helical geometry of many of the metallic elements such as pressure armour and tensile armour layers of a flexible riser. The general design philosophy of the layer is defined in API 17J (American Petroleum Institute) in terms of the stress "utilisation" factor that specifies the maximum allowable average hoop stress in the layer, which is conventionally produced by the elastic stress analysis. The layers are subjected to severe cyclic bending and twisting deformation during manufacturing of the pipe which makes the material to exceed the yield point. Consequently, residual stresses are developed in the pipe material and variable amounts of non zero stresses exist in the metallic layers of the newly manufactured pipes. An attempt has been made to model the amount of residual stress evolved during manufacturing stage for two different metallic layers, namely; pressure armour and tensile armour layers and its effects on overall pipe's performance while in service. The strategy is to apply the finite element (FE) method by creating a3 dimensional wire model of the segment of pipe. Solid structural elements with plasticity were employed for the analyses. Kinematic hardening with Baushinger effect, contact and friction effects were also taken into account. Precise boundary conditions were applied to the model for elastic-plastic bending. The resulting residual stresses have been transferred to 3D axisymmetric model to investigate the internal and external pressure effects. This new procedure was carried out for both layers satisfying equilibrium and compatibility conditions for the pressure and tensile armours to find the common interface pressure and contact loading. FAT (Factory Acceptance Test) condition is simulated to investigate the level of residual stress variation. Experimental measurements of residual stress by X-Ray diffraction are in well agreement with FE results.

Stab resistant body armour had been used throughout history, with examples ranging from animal hide construction to the moulded Polycarbonate units typically used by United Kingdom (UK) Police Officers. Such protective articles have historically, and continue to present a number of issues which have shown to impair the operational performance of its wearer including but not exclusive to poor thermal regulation, large masses, and reduced manoeuvrability. A number of developments have been made in an attempt to minimise the effects of such issues. One potential solution yet to be fully explored is the utilisation of Additive Manufacturing (AM) technologies. In recent years the use of such manufacturing technologies, particularly Laser Sintering, has successfully demonstrated their suitability for a range of high performance applications ranging from Formula 1® to aerospace. Due to the fundamental additive nature of AM build processes, the utilisation of such technologies have facilitated the realisation of design concepts that are typically too expensive, difficult or impossible to create using traditional manufacturing processes. In order for AM technologies to be used for the generation of stab resistant body armour a number of historical issues and performance characteristics fundamental to ensure stab resistance is achieved must be satisfied. This body of research firstly evaluated the stab resistive performance of two of the most common materials suitable for Laser Sintering as highlighted by an initial review of AM technologies. Once an appropriate material had been highlighted it was used as the basis for further experimental testing. Such tests focussed on minimising the material thickness required to maintain an appropriate level of stab resistance within United Kingdom Home Office Scientific Development Branch (HOSDB) KR1-E1 requirement of 24 Joules of stab impact energy. Test results demonstrated that specimens manufactured from Duraform EX® required a minimum single layer thickness of 11.00 mm, and a dual layer total thickness of 9.00 mm to provide an appropriate level of stab protection within the HOSDB KR1-E1 standard. Coupled with the results generated from an investigation identifying the overlapping/imbricated assembly angle required to maintain an appropriate level of coverage across a scale structure, the stab resistant characteristics initially identified were used for the development of an imbricated scale-like assembly. Additional design features were also investigated to further minimise the total thickness of the final element design and corresponding assembled imbricated structure such features included angling strike surfaces and integrating a dual layered structure within individual elements. When the finalised imbricated assemblies were stab tested, they successfully demonstrated levels of stab resistance to the UK HOSDB KR1-E1 impact energy of 24 Joules.

Adding a surface rock layer (also called rock armor or rock mulch) to constructed slopes improves erosion resistance but has had mixed effects on revegetation. This study investigated the effects of rock layer depth (no rocks, 10-, 15-, and 20-cm rock layers) and rock size (5-20cm diameter rocks) on vegetation cover. Seeding was applied four times in the first 2 years. After 3 years, plots with a rock layer averaged 7% vegetative cover compared to 85% on plots without a rock layer. There was a nonsignificant trend toward less vegetation with a deeper rock layer.

Coastal regions are extensively utilized by constructing coastal structures and facilities, as a result of the economical potential they offer. In designing and construction of coastal structures, it is important to achieve an optimum design satisfying both the stability and the engineering economy requirements effectively, regarding the natural balance of the coastal region. In this study, first step model tests on the stability of the coastal protection structures of Eastern Black Sea Highway Project under construction, proved that the structure is not stable and safe under severe wave action. As an innovative approach, using Van der Meer&
#8217
s approach and berm design guidelines alternative cross sections were generated.In the second step of the model studies, 8 different models were constructed using a model scale of 1/31.08 and they were tested both for breaking and non-breaking waves. The experiments took place in the Coastal and Harbor Engineering Laboratory of the Middle East Technical University, Civil Engineering Department. The newly designed and optimized berm type structure was proved to be successful and economical.

Bedload transport has long been known for its complexity. Despite decades of research, significant gaps of understanding exist in the ability to assess and predict bedload movement. This work introduces a comprehensive bedload database that is a compilation of field samples collected over the past 40 years; compares prediction formulae using a subset of the database; evaluates the influence of the armor layer on stream response to sediment input based on a hypothesis linked to one of the tested formulae, presents a mathematically manipulation of the empirical Pagosa Good/Fair formula for bedload transport into a format similar to the semi-empirical Parker Surface-Based 1990 formula; and addresses the complications of bedload transport by collecting bedload samples on a stream in Central Utah. A comprehensive review of available bedload data resulted in a publicly available database with more than 8,000 individual bedload samples on gravel bed streams. Each measurement included extensive and detailed information regarding channel, site, and hydraulic characteristics. A subset of this database was used to compare four calibrated (a single calibration point of a measured bedload transport rate near bankfull discharge is used to improve formula prediction accuracy) and two un-calibrated bedload prediction formulae. The four calibrated formulae include three semi-empirical (a theoretical treatment adjusted to fit bedload measurements) formulae and one empirical (solely based on regression of bedload measurements) formula; the two un-calibrated formulae are both semi-empirical. Of the formulae compared, the empirical Pagosa Good/Fair formula (a calibrated formula) provided the most accurate prediction results with an overall root mean square error of 6.4%, an improvement of several orders of magnitude over the un-calibrated formulae. The Pagosa Good/Fair formula is cast in a form similar to the Parker 1990 formula, suggesting that criticisms stating that the empirical Pagosa method lacks a theoretical basis are unfounded. The hypothesis of equal mobility that states the gradation of the average annual gravel bedload yield for a given stream matches the particle size distribution of the subsurface material is evaluated with relation to the armor layer. Equal mobility is found to correlate to armor layer such that lower armor ratios indicate a greater tendency to uphold the equal mobility hypothesis and increasing armor ratio values tending to move toward supply limited conditions. This correlation provides an upper limit for lightly armored streams. Bedload sampling efforts described in this work compare the Helley-Smith sampler with the net trap sampler and duplicate previous observations that bedload transport collected using net traps increase more rapidly with discharge than for data collected using Helley-Smith samplers. An alternative, relatively low-cost method for collecting bedload during relatively high discharges on highly urbanized streams is also proposed.

Master thesis presents overview of existing types of check valves, their features, uses and issue called "cracking". Experimental part of this thesis focuses on the lift and swing check valves. Results of the measurement are evaluated from non-stationary flow point of view by developing and analyzing static and dynamic characteristics. This thesis takes into account losses and dynamic effects as main viewpoints. Two methods for measuring non-stationary velocities are used. Direct method called Gibson and indirect method laser doppler anemometry. Goal of the master thesis is to increase understanding of the check valves and their applicability.

Coastal defense structures are built in order to protect valuable coastal regions from the destructive effects of the waves. Due to the cost of coastal defense structures and the economical potential of the coastal regions, failure of such structures could cause loss of high amounts of investment. Therefore in the design and construction of coastal structures, it is of vital importance to achieve an optimum design which is not neither underdesigned nor overdesigned. In this study, Submerged Berm type coastal defense structures with several different cross-sections were tested for stability under storm conditions. Damage analyses of the different models were carried out to compare the structure characteristics under storm conditions and to obtain the most economical and stable cross-section. For the model studies, 5 different models were constructed by using Van der Meer&rsquo
s approach and berm design guidelines. Models were constructed with a model scale of 1:31.08 in the wave flume in the Coastal and Harbor Engineering Laboratory, Civil Engineering Department, METU. The newly designed and optimized berm type structure was proved to be successful and economical.

The broad field of engineering is facing a paradigm shift where advanced optimization methods and techniques are more often used to solve complex problems. Most of these problems either require the analysis of a large amount of data or the solving of complex calculations, or even both. This dissertation aims to develop an understanding of non-linear optimization algorithms applied to a complex engineering design problem: a multi-layer plate under a ballistic impact. To solve a complex design engineering problem, the most efficient way is to combine non-linear optimization algorithms with a software capable of simulating the model and event. Accordingly, the first part of this document focuses on developing a Python script of the simulation model system using Abaqus API. The usage of an Abaqus Python script to simulate the event allows to generate specific variables and post-processing outputs essential to its posterior integration with optimization algorithms. Nevertheless, the development of a model that simulates a ballistic impact is complex and, thus, a sounding understanding on the physics and mechanics behind such an event are properly discussed. These insights are then used to validate the dynamic response and equilibrium of the simulated model. Furthermore, several modeling strategies are considered and analyzed throughout the first part of this document. The second part of this dissertation aims to acquire a comprehensive understanding of three optimization algorithms: Particle Swarm Optimization (PSO), Genetic Algorithm (GA) and Simulated Annealing (SA). The performance and efficiency of each algorithm, as well as numerous programming and optimization strategies, are tested in four different benchmarks. Each benchmark increases in complexity regarding its precedent and they all use the Abaqus Python script previously developed. This dissertation culminates in a multi-objective optimization procedure that uses the most efficient algorithm out of the three algorithms tested in the previous benchmarks. This multi-objective procedure uses every single-objective formulation, variables and constraints from the previous benchmarks which results in a highly non-linear problem. The results from this complex optimization problem are analyzed using and discussed.
O amplo ramo da engenharia enfrenta uma mudança de paradigma, na qual métodos e t écnicas avançados de otimização são cada vez mais usados para resolver problemas complexos. A maioria desses problemas requer a análise de uma grande quantidade de dados ou requer a resolução de cálculos complexos, ou até mesmo ambos. Esta dissertação tem como objetivo desenvolver um estudo compreensivo de algoritmos de otimização, aplicados a um problema complexo de projeto de engenharia: uma placa com multiplas camada sob um impacto balístico. Para resolver um problema complexo de engenharia de projeto, a forma mais eficiente consiste em combinar algoritmos de otimização não-linear com um software capaz de simular o modelo e o evento. Assim, a primeira parte deste documento é focada no desenvolvimento de um código em Python do modelo de simulação através da API do Abaqus. O uso de um código Python para simular o evento permite gerar variáveis específicas e resultados de pós-processamento que são essenciais para sua posterior integração com algoritmos de otimização. No entanto, o desenvolvimento de um modelo que simule um impacto balístico é complexo e, portanto, uma compreensão intrínseca sobre a física e a mecânica de tal evento é discutido adequadamente. Esses conhecimentos adquiridos são posteriormente usados para validar a resposta dinâmica e o equilíbrio do modelo simulado. Além disso, várias estratégias de modelagem são consideradas e analisadas ao longo da primeira parte deste documento. A segunda parte desta dissertação visa adquirir uma compreensão abrangente de três algoritmos de otimização não-lineares: otimização por enxame de partículas (PSO), algoritmo genético (GA) e recozedura simulada (SA). O desempenho e a eficiência de cada algoritmo, bem como numerosas estratégias de programação e otimizaçãoo, são testados em quatro benchmarks. Cada benchmark aumenta em complexidade em relação ao seu precedente e todos usam o código Python do modelo em Abaqus previamente desenvolvido. Esta dissertação culmina num processo de otimização multi-objetivo que utiliza o algoritmo mais eficiente dos três algoritmos testados nos benchmarks anteriores. Este procedimento multi-objetivo utiliza todas as formulações, variáveis e restrições das formulações dos benchmarks anteriores, o que resulta num problema altamente não linear. Os resultados desse complexo problema de otimização são analisados e discutidos.
Mestrado em Engenharia Mecânica

Technology advances continue to revolutionise military equipment. The development of new firepower induces an interest in the enhancement of protection gear, both for transportation vehicles and personnel. There has been a significant amount of research of methods to increase protection capabilities without increases in the weight of a given defence system. This dissertation seeks to develop an optimisation tool that results in light-weight armour plates without compromising protection capabilities. A thorough study on the propagation of elastic and plastic stress waves aims for a better understanding of how an armour system behaves upon ballistic impact. The first part of this dissertation focuses on the development of a Python script that provides an efficient approach to model generation in Abaqus. It enables the user to avoid time consuming actions when designing ballistic test models to later simulate through the software. This script is also used to validate the theory behind elastic and plastic stress wave propagation while also being able to access output databases and interpret obtained results. The importance of the script is relevant for the second part of the dissertation, which takes advantage of the Abaqus Python Application Programming interface (API) to perform optimisation procedures automatically. Focusing particularly on the application of the particle swarm optimisation algorithm, this work continuously improves the efficiency and accuracy of the mentioned algorithm by dividing three different optimisation problems into several experiments. Each one of the experiments is carefully defined to highlight the impact of a specific operating parameter of the algorithm. A validation of the stress wave propagation and how it is affected upon contact with layered media is carefully conducted through a series of different analysis approaches. It is shown that the plastic stress wave propagates slower than the elastic one and that plastic deformation affects the properties of the generated stress wave, such as wavelength. The implemented particle swarm optimisation algorithm proved to be an effective approach to problem solving, however, for complex problems the operational parameters must be carefully chosen.
Os avanços na tecnologia continuam a revolucionar equipamentos militares. O desenvolvimento de novas armas de fogo induz interesse no aprimoramento de equipamento de proteção, para veículos de transporte e pessoal. Tem havido uma quantidade significativa de investigação de métodos para aumentar as capacidades de proteção sem aumento de peso de um dado sistema de proteção. Esta dissertação tem como objetivo o desenvolvimento de uma ferramenta de otimização que resulta em placas de armadura de baixo peso sem comprometer capacidades de proteção. Um estudo cuidadoso acerca da propagação de ondas de tensão elásticas e plásticas procura compreender a forma como um sistema de armadura reage após um impacto balístico. A primeira parte desta dissertação foca-se no desenvolvimento de um código em Python que fornece uma abordagem eficiente à geração de modelos no Abaqus. Isto permite que o utilizador evite ações que consumam tempo ao criar modelos de teste balístico para simular mais tarde através do software. Este código é também usado para validar a teoria por detrás da propagação de ondas de tensão elásticas e plásticas e ao mesmo tempo habilitar o acesso a dados de saída do software e interpretar resultados obtidos. A importância do código é relevante para a segunda parte da dissertação, que tira vantagem da interface de aplicação e programação do Abaqus Python (API) para executar procedimentos de otimização de forma automática. Com foco em particular na aplicação do algoritmo de otimização por enxame de partículas, este trabalho melhora continuamente a eficácia e precisão do algoritmo mencionado através da divisão de três diferentes problemas de otimização em várias experiências. Cada uma das experiências é cuidadosamente definida para destacar o impacto de um parâmetro operacional específico do algoritmo. A validação da propagação da onda de tensão e como é afetada após contacto com um meio material de múltiplas camadas é cuidadosamente estudada através de séries de diferentes análises. É mostrado que a onda de tensão plástica se propaga mais lentamente que a elástica e que deformação plástica afeta as propriedades da onda de tensão gerada, tal como o comprimento de onda. O algoritmo de otimização por enxame de partículas implementado prova ser uma abordagem eficaz para a resolução de problemas, no entanto, para problemas complexos os parâmetros operacionais devem ser escolhidos com cuidado.
Mestrado em Engenharia Mecânica

碩士
中興大學
水土保持學系所
95
The study uses three kinds of experiment methods to simulate articulated armor-layer system to apply for control soil erosion, protection on downstream bed of the hydraulic structure, and then evaluation of the effects of armor-layer system. First, in sloping fields protection experiment, to determine the three basic elements which are light-shielding rate, surface roughness and apparent opening size of three common artificial geo-textiles in Taiwan and woodblock gridnets by related experimental equipment uses artificial rainfall instrument and hydraulic launders. The testing conditions are the gradients of 35˚ and 45˚ and the rainfall intensity of 130mm/hr. At last, evaluate the anti-erosion efficiency of woodblock gridnets and artificial geo-textiles. Second, in downstream bed of the hydraulic structure protection experiment, it uses differently constructive models of armor-layer system to test the protective efficiency and to observe the types of score holes at different rates of flows and drop heights of conditions. Last, in the experiment of sediment protection under channel bed, applying different construction model of armor-layer system to test protective efficiency and compared with protective efficiency without geo-textiles protection. The results were summarized as below. In the experiment of sloping field protection, the researcher found the anti-erosion efficiency of common artificial geo-textiles in Taiwan and light-shielding rate are proportional. According to the soil erosion test, the woven three-D netting with the light-shielding rate of 83.13% has the highest anti-erosion efficiency. In contrast to other artificial geo-textiles, the woodblock gridnets without high light-shielding rate could protect raindrop impact, but use uniform distribute woodblock to increase the anti-erosion efficiency upper than 34%. In downstream bed of the hydraulic structure protection experiment found the different constructive models of armor-layer system has different types. Although armor-layer system can slow down the rate of the score holes, the differences between scores holes don’t have the increasing phenomenon. No matter what kind of types of armor-layer system in the experiment of sediment protection under channel bed, armor-layer system not only plays the role of decreasing the efficiency of erosion, but also has higher relationship between the rate of anti-erosion and the density of armor-layer.

Ралко А. В. Структурно-фазовий стан поверхневих шарів армко-заліза після лазерного легування сумішшю порошків нікелю, кобальту та хрому : кваліфікаційна робота магістра спеціальності 104 «Фізика та астрономія» / наук. керівник О. В. Смоляков. Запоріжжя : ЗНУ, 2020. 53 с.
UA : В роботі 53 сторінок, 13 рисунків, 2 таблиць та було використано 60 літературних джерел. Об’єкт дослідження – стрктурно-фазовий стан поверхневих шарів армко-заліза, після лазерного легування сумішшю порошків металів групи заліза. Мета роботи: встановити можливість створення за допомогою метода лазерного легування високоентропійного сплаву в поверхневих шарах армко-заліза. Метод дослідження – рентгенівський фазовий, металографічний, вимірювання мікротвердості та метод растрової електронної мікроскопії. В кваліфікаційній роботі за допомогою рентгенівського фазового аналізу було досліджено фазовий склад зразків у вихідному стані та після лазерної обробки на повітрі. Проаналізували структуру та фізико-механічні властивості при поверхневого шару зразків після лазерного легування та визначили значення мікротвердості за глибиною в зоні лазерної дії.
EN : In the work 53 pages, 2 tables and 13 figures, was used 60 literary sources. The object of the study is the structural-phase state of the surface layers of armco-iron, after laser doping with a mixture of powders of metals of the iron group. Purpose: to establish the possibility of creating a high-entropy alloy in the surface layers of armco-iron using the method of laser doping. The research method is X-ray phase, metallographic, microhardness measurement and scanning electron microscopy method. In the qualification work with the help of X-ray phase analysis, the phase composition of the samples in the initial state and after laser treatment in air was investigated. The structure and physico-mechanical properties of the surface layer of the samples after laser doping were analyzed and the values of microhardness in depth in the laser action zone were determined.