The geotechnical properties of municipal solid waste (MSW) such as compressibility, shear strength and stiffness are of prime importance in design and construction of landfills. However, it is not well clear how the stress-strain and strength characteristics vary with time as the biodegradation of waste continues in the landfill. There is also a need to address the variability of MSW properties and their role in landfill design. The present thesis proposes models for the analyses of stress-strain response of MSW in undrained and drained conditions. The proposed models are based on critical state soil mechanics concept and the modified cam clay model is extended to consider the effects of creep and biodegradation. The models are examined with reference to experimental data and published results of MSW in the form of stress strain response. In addition, the experimental results and the data from published literature are also compared with predictions from hyperbolic model. The proposed models are able to capture the stress strain response of MSW in undrained and drained condition adequately. The applicability of proposed model is presented in terms of shear strength ratio, stiffness ratio and settlement for typical landfill cases. In order to examine the influence of model parameters on shear strength, stiffness ratio and settlement, multilinear regression equations are developed based on response surface method (RSM) for different coefficients of variation (COVs). The effect of variability associated with model parameters is examined using reliability analysis. For better understanding, the present thesis is divided into following seven chapters. Chapter 1 is an introductory chapter, in which the need for use of the constitutive models and its use in engineering response analysis of MSW is presented. Further, the organization of thesis is also presented. Chapter 2 presents various studies with regard to the engineering properties of MSW available in the literature. Different models and approaches proposed by various researchers for the prediction of stress-strain response, time dependent behavior and settlement analysis of the MSW are presented. The uncertainty associated with engineering properties and available methods for reliability analysis and the use of response surface method are presented. Finally, based on the literature review, the scope of the thesis and summary of chapter are presented at the end. Chapter 3 presents composition of MSW, detailed description of the sample preparation, methods adopted in the experimental program and test results of one dimensional compression and consolidated undrained tests. Based on the experimental observations, a constitutive model for municipal solid waste for undrained condition in the framework of modified cam clay model considering mechanical creep and biodegradation mechanisms is proposed. It also provides detailed description of the selection of the input parameters required for the proposed model. Further, the detailed derivation of proposed model and the discussion on evaluation of the input model parameters from triaxial and consolidation tests are presented. The model is examined with reference to the experimental data and published results. The stress strain behavior of MSW is compared with the prediction of stress strain response from hyperbolic model. The comparison of stress strain response is well captured using proposed model for all levels of strain. The major conclusions from the study are presented at the end. Chapter 4 presents experimental results of consolidated drained tests. A constitutive model for MSW for drained condition in the framework of modified cam clay model considering mechanical creep and biodegradation mechanisms is proposed. The model is examined with reference to the experimental data and data from published literature. In addition, stress strain behavior of MSW is compared with the predictions from hyperbolic model. The comparison of stress strain response is well captured using proposed model for all levels of strain. The major conclusions from the study are presented at the end. Chapter 5 presents the applicability of proposed models in terms of shear strength ratio and stiffness ratio for a typical landfill condition. Based on response surface method (RSM), multilinear response surface equations are developed for different variables ( M, λ.b.c.d.Edg ) for different percentages of strain for 10 and 20% COVs of the model parameters. The effect of variability of model parameters is presented in terms of results of reliability analysis for specified performance functions. The major conclusions from the study are presented at the end. Chapter 6 presents an approach for the settlement evaluation of MSW for a typical landfill case of 30 m high. Based on RSM, multilinear response surface equations are developed for the calculation of MSW settlement for 30 years for 10 and 20% COVs. The effect of variability of model parameters is evaluated in term of reliability index for performance function specified in terms of landfill capacity. The major conclusions from the study are presented at the end. Chapter 7 presents a brief summary and conclusions from the various studies reported in the present thesis.

The concept of reinforcement was developed in late 20th century and since then till the recent past there are many works carried out on the effect of fibers in imparting strength and stiffness to the soil. Experimental investigations on fiber reinforced soils showed an increase in shear strength and reduction in post peak loss of strength due to the reinforcement. Analytical/mechanistic models are developed to predict the stress-strain response of fiber reinforced soil (under discrete framework, energy dissipation methods, force equilibrium methods etc). Numerical investigations are also carried out, and it was observed that the presence of random reinforcing material in soils make the stress concentration diffuse more and restrict the shear band formation. Soil properties vary from point to point at micro level and influence stress mobilization. Hence, there is a need to carry out probabilistic analysis to capture the effects of uncertainties and variability in soil and their influence on stress-strain evolution. In the present thesis an attempt has been made to propose a mechanistic model that predicts the stress-strain response of fiber reinforced soil and also considers the effect of anisotropy of fibers. A stochastic/probabilistic model is developed that predicts the stochastic stress-strain response of fiber reinforced soil. In addition, probabilistic analysis is carried out to observe the effect of number of fibers across the shear plane in imparting shear resistance to soil. The mechanistic model and stochastic models are validated with reference to the experimental results of consolidated undrained (CU) triaxial tests on coir fiber reinforced red soil for different fiber contents. The entire thesis is divided into six chapters. Chapter-wise description is given below. Chapter one presents a general introduction to the works carried out on fiber reinforced soils and also the investigations carried out on probabilistic methodologies that takes into account the soil variability. Thus, the chapter gives an outline of the models developed under mechanistic and probabilistic frameworks in the thesis. The objectives and organization of the thesis are also presented. Chapter two presents a detailed review of literature on the role of fibers in fiber reinforced soil. The details of experimental investigations carried out and models developed are explained briefly. Also, the literature pertaining to the role of variability in soil on its engineering behavior is presented. Based on the literature presented in this chapter, concluding remarks are made. Chapter three presents the details of a new mechanistic model developed based on modified Cam-clay model. This model considers the effect of fiber content and also the effect of anisotropy due to fibers. The predictions from the mechanistic model are compared with the experimental results. Under anisotropic condition, as angles of inclination of fiber vary from 0° to 90° with the bedding plane, it is observed that the strength increment in the reinforced soil is not as significant as that observed in isotropic case. Horizontal fibers turn out to be most effective since they are subjected to maximum extension thereby inducing tensile resistance which in turn contributes for strength increase in fiber reinforced soil. Chapter four presents a new approach to predict the stochastic stress-strain response of soil. Non-homogeneous Markov chain (multi-level homogeneous Markov chain) modeling is used in the prediction of stochastic response of soil. The statistical variations in the basic variables are taken into account by considering the response quantities (viz. stress at a given strain or settlement at a given load level) as random. A bi-level Homogeneous Markov chain predicts the stochastic stress-strain response efficiently. The predicted results are in good agreement with the experimental results. An illustration of this model is done to predict the stochastic load-settlement response of cohesionless soil. A simple tri-level homogeneous Markov chain model is proposed to predict settlements of soil at a given load for an isolated square footing subjected to axial compression. A parametric study on the effect of correlation coefficient on the prediction of settlements is performed. Chapter five presents the results of probabilistic analysis carried out to determine the effect of number of fibers across the shear plane in improving the shear strength of soil. It is observed that as the percentage of fibers in the specimen increases, the probability of failure of specimen under the same stress condition reduces and thus the reliability of the fiber reinforced soil system increases. In Chapter six, a summary of the important conclusions from the various studies reported in the dissertation are presented.

Cellular materials like aluminum foam which is the subject of interest here are generally characterized by high energy absorption capacity per unit weight. Materials of this category can be ideal for applications such as packaging and vehicle body structures for enhanced impact safety. A particularly well-known variety of closed-cell aluminum foam is designated as Alporas, which is studied here. From a viewpoint of mechanical behavior, the foam being considered can be represented using either a detailed cellular approach capturing the voids present in foam structure or a phenomenological approach in which experimental stress-strain response is assigned a-priori to solid elements filling up the space occupied by a foam geometry. Both modeling approaches are studied in the present work. It has been shown for the first time that stress-strain behavior under compression including densification can be predicted well with a Kelvin cell-based model, although scope for further improvement exists. Based on a novel combination of compression tests at low strain rates in a UTM and medium strain rates in low velocity impact tests, a relation between foam strength and strain rate has been proposed. This effect of strain rate on strength is captured in a finite element model for analysis using an explicit code with contact simulation capabilities and the predictions for projectile impact tests at higher strain rates using a gas gun-based device have been found to match commendably with results obtained from the said tests.

Die Arbeit stützt sich überwiegend auf die Ergebnisse experimenteller Untersuchungen. Einaxiale Zugversuche an scheibenförmigen Probekörpern bildeten die Basis für die Beschreibung des Tragverhaltens in Form von Spannungs-Dehnungs-Linien. Da die Durchführung von Zugversuchen bekanntlich nicht ganz problemlos ist, wird der Versuchsaufbau besonders sorgfältig dargestellt. Mängel und deren Auswirkung auf die Versuchsergebnisse werden ausführlich diskutiert. Für die Beurteilung der Verbundeigenschaften der Bewehrung ist der Umfang der Kontaktfläche mit der Matrix ein wichtiger Parameter. Es wurde ein Verfahren für die Ermittlung dieser und anderer geometrischen Eigenschaften der Bewehrung entwickelt. Elektronische Aufnahmen von klassischen Dünnschliffen werden dazu mit einem digitalen Bildauswerteprogramm analysiert. Die Berücksichtigung einer Vielzahl von Einflüssen ermöglicht erstmals die reproduzierbare Bestimmung des Umfanges der Kontaktfläche zwischen den Fasern und der Matrix sowie die Querschnittsfläche der Faserbündel in der Matrix ohne subjektive Einflüsse. Das Tragverhalten von unidirektionalen und textilen Bewehrungen aus AR-Glas Filamentgarnen wird mit experimentellen Methoden untersucht. Die Basis bilden in einaxialen Zugversuchen an Dehnkörpern aufgenommene Spannungs-Dehnungs-Linien. Schon bei einer Bewehrung aus unidirektionalen Multifilamentgarnen treten Phänomene auf, die von Bewehrungen aus kompakten, homogenen Querschnitten (Stäben oder Drähten) nicht bekannt sind. Die Multifilamentgarne können selbst schon als Verbundwerkstoff bezeichnet werden, dessen Eigenschaften in einem großen Wertebereich variieren. Mit der textilen Verarbeitung von Multifilamentgarnen werden die (Verbund¬¬-)Eigenschaften entscheidend verändert. Ganz wesentlich ist das Hinzufügen von weiteren Faserscharen und den für die Herstellung der Textilien notwendigen Nähgarnen. Durch die Verarbeitung ändern sich auch Form und Packungsdichte der Multifilamentgarne. Das Zusammenspiel all dieser Einflüsse und die Variationsmöglichkeiten bei der Kombination aller Parameter führen zu einem teilweise deutlich verändertem Tragverhalten des textilbewehrten Betons gegenüber unidirektional bewehrtem Beton. Auf der Basis einfach handhabbarer Modelle wird versucht, Charakteristika des Tragverhaltens zu erklären. Beim textilbewehrten Beton ist jedoch oft kein eindeutiger Zusammenhang erkennbar, weil sich mehrere Einflüsse überlagern. Trotzdem ist es gelungen, zahlreiche, für den textilbewehrten Beton typische Besonderheiten aufzuzeigen und deren Ursachen zu klären. Den Abschluss bilden Überlegungen zur Optimierung der textilen Bewehrungen, die sich aus den beobachteten Phänomenen und deren Ursachen ableiten. / This thesis is mainly based on results of experimental methods. Uniaxial tension tests on strain specimens provide a basis for a description of the load bearing behaviour in the form of stress-strain-curves. It is well known, that the accomplishment of tension tests causes several problems. Therefore the test set-up is described in detail. Deficiencies and their impact on test results are discussed extensively. For the assessment of bond properties the perimeter of the contact area between fibres and matrix is a crucial parameter. A new procedure has been developed for estimating this and other geometrical properties of the reinforcement. Digital images of traditional thin section petrography are analysed with digital image analysis software. The consideration of a multitude of influences enables a reproducible determination of the perimeter of the contact area between fibres and matrix as well as the cross sectional area of the fibre bundles for the first time without subjective influences. The load bearing behaviour of unidirectional fabric reinforcement made from AR-glass filament yarns is examined with experimental methods. Stress-strain-curves from uniaxial tension tests on strain specimen provide a basis. Reinforcements of unidirectional multi filament yarns show already phenomenon?s that are not known from reinforcements with compact homogeneous cross sections (bars or wires). Multi filament yarns could be indicated as an composite material itself whose properties vary in a wide range. During fabric production with textile technologies the (bond-)properties are subject to crucial changes. The adding of extra layers of yarns and needle thread required for connecting these layers are of vital importance. Textile processing changes shape and packing density of the multi filament yarns. The interaction of all these influences and the possible range of combining all parameters lead to pronounced changes in the mechanical properties of textile reinforced concrete also compared to unidirectional fibre reinforcement. Using simple to handle models this work attempts to explain characteristics of the mechanical behaviour. However, for textile reinforced concrete there is often not a clear connection visible. Although numerous typical characteristics of textile reinforced concrete and their causes has been identified. Finally some considerations for optimising fabric reinforcements are given, which has been derived from observed phenomenons and their causes.

This master thesis deals with computational stress-strain analysis of the tailskid of airplane L410 NG with main focus firstly the check current design of the tailskid and then the design another design solution with the able to absorb as much as possible the deformation energy. Solution of this problem is performed using computational modeling utilizing numerical simulation of quasi-static and crash deformation load of the tailskid with using explicit Finite Element Method (FEM) in program ABAQUS v6.14. After the introduction with problem situation and tailskid assembly introductory part is devoted to the research study of various designs of the tailskid for different types of airplanes. There follows these theoretical general principles of thin-walled structures and buckling of them. Before the creating of the computational model itself, the explicit form of the Finite Element Method is better described. The conclusion of this thesis deals with the mutual comparison of the most advantageous design variants of the tailskid and the selection of the most suitable one of them for the airplane L410 NG.

The objective of this diploma thesis is the design of a device that measures the vehicle’s centre of gravity height position. The first part defines individual methods of measurement using various measuring equipment. The next part deals with the definition of requirements for the device and the definition of the design. A stress-strain analysis was executed for selected components. This diploma thesis describes the preparation process of the vehicle and the device for the measurement. The next part is dedicated to the design of the measuring chain and to the evaluation of the results. The thesis concludes with a theoretic analysis of the measurement inaccuracy.

This thesis deals with problems of the hip endoprosthetics area, namely total endoprosthesis (TEP) with Burch-Schneider (BS) split, in which there are many problems in clinical practice. The hip joint load depends on the patient weight and the performed activity. Sedentary job, little exercise, a lot of stress or poor eating habits and overweight associated with it affect negatively hip joint. Increasing hip joint wear and its pain in movement is necessary in several cases to be solved by a surgical procedure in which TEP is applied. When selecting and subsequently applying individual TEP, it is important to pay attention to creating conditions which will allow good fixation. In case of worse mechanical properties of bone tissue, it is very problematic to ensure stability of the implant. Based on several classifications which assess the degree of hip joint damage, it is possible to select a suitable TEP. The BS split, on which this work is focused, is dominantly used in cases of large defects in the acetabulum area. The use of this cage allows to bridgelarge defects and create a new centre of rotation of the hip. Knowledge of the mechanical properties of hip bone tissue can significantly affect the prediction of BS split damage. For this purpose, it was necessary to perform a biomechanical study, which is focused on the influence of worse mechanical properties of bone tissue on BS split failure. The computational modelling using finite element method implemented in the ANSY S software was used for the solution, which enables to solve the mechanical interaction between bone tissue and TEP with BS split. Due to the absence of bone tissue data before application of TEP with BS split, the variants before application of TEP and after application of resurfacing and standard TEP were solved. All variants were solved with the material properties of bone tissue that were determined based on CT images. In addition, all variants were solved for the case of degraded mechanical properties. Based on the numerical simulations results and the Mechanostat hypothesis, a bone tissue analysis of the hip joint was performed before and after application of TEP and TEP with BS split. The results show the influence of the computational model level, which considers the distribution of bone tissue through the inhomogeneous model of the material. Therefore, the degraded mechanical properties have a major impact on the stability and strain of the BS split, particularly in the cranial part of the acetabulum.

Submitted master thesis deals with stress - strain analysis of jaw, with dental implant. The implant serve as a suitable pillar for crown or dental bridge, when one or more teeth are lost. The project is oriented on BOI (basale - oseo - integrable) dental implant type, which is produced by DENTALIHDE company. Stress – strain condition of the mandible system with implant have been established by computational simulation, with use of the final elements method. Important part of down jowl is simulated on with EDS and EDDS applied types of implants. After implementation the implant begins to heal. Therefore the special attention is paid to stress - strain states on various level of osteointegration. There is a detail description of production of single part computational model and his solving in the master thesis. Presentation of large chapter with results and subsequent alteration stress - strain analysis is part of the master thesis. Program SolidWorks 2005 was used to create the geometric model. Computational model and the actual solving was accomplished with use of ANSYS 11.0 and ANSYS Wor-kbench systems.

This diploma thesis deals with fixation of the lower jaw fractures using commercially produced fixators. The topic was researched on the basis of the available literature. The thesis also indicates basic anatomy of the surveyed area and nowadays the most commonly used materials. Subsequently, the stress-strain analysis of the lower jaw with the applied angular stable fixation plate was performed. The solution was performed for the lower jaw with a fracture in the area of the condyle with different types of fixation plates made of CP-Ti Grade 4. In addition, the strain analysis of the healed lower jaw with the fixators after the defect in the area of chin and angle was performed. The mechanical interaction analysis of the lower jaw with defect and applied fixation plate was solved by using computational modeling with variational approach, in use of the finite element method in Ansys Workbench 18.1. The thesis also describes in detail the creation of a computational model of the system and the subsequent solution.

Yttria-stabilized zirconia-based thermal barrier coating systems are the most widely used commercial coatings in the industry, with practical applications in aircraft engines and land-based power turbines. The purpose of thermal barriers is primarily to protect the substrate from high temperatures and also to increase its oxidation resistance. Currently, concerning the relatively frequent volcanic eruptions and increasing air traffic intensity in desert areas, increased attention is being paid to the development of new thermal and environmental coatings that will withstand the so-called CMAS attack and still successfully meeting the strictest requirements of the aerospace industry. Two newly developed experimental coatings consisting of three successive layers have been developed for this work. The upper two layers are thermal insulating ceramic coatings, where two different uppermost coatings were deposited. The first uppermost layer of the coating is a mixture of mullite and hexacelsian in a ratio of 70/30 wt. %. The second upper most type of coating consists of Al6Si2O13 + MgAl2O4 + BaCO3 in a ratio of 6:3:1 wt. %. The interlayer is made of the commercially utilized yttria-stabilized zirconia. The metallic CoNiCrAlY coating, which is directly deposited on the nickel-based superalloy MAR-M247, fulfils a compensatory function between the mechanical properties of the nickel superalloy and the ceramic coating. The thermal and environmental barrier system was deposited using air plasma spraying (APS) technology. The main objective of this work was to evaluate the effect of the newly developed thermal and environmental barrier coating, which has a high potential for the protection of component surfaces in an aggressive environment, on isothermical and thermomechanical fatigue behaviour of nickel-based superalloy MAR-M247. Low cycle fatigue tests were performed in strain control mode with constant strain amplitude on both uncoated and TEBC coated superalloy. Fatigue hardening/softening curves, cyclic stress-strain curves and fatigue life curves in the representation of total strain amplitude, plastic strain amplitude and stress amplitude on the number of cycles to failure were obtained. Microstructural analysis of MAR-M247 superalloy and a newly developed experimental coating was performed in a scanning electron microscope. The fatigue crack initiation sites were identified and the process of fatigue crack propagation was described. The dislocation arrangement after fatigue loading of MAR-M247 was investigated in a transmission electron microscope. The findings of isothermical and thermomechanical low cycle fatigue behaviour of uncoated and TEBC coated MAR-M247 superalloy and identification of damage mechanisms presented in this dissertation will improve the estimation of safe-life that is particularly relevant to aircraft engines components.