This paper presents a static analysis of functionally graded single and sandwich beams by using an efficient 7DOFs quasi-3D hybrid type theory. The governing equations are derived by employing the principle of virtual works in a weak form and solved by means of the Finite Element Method (FEM). A C1 cubic Hermite interpolation is used for the vertical deflection variables while C0 linear interpolation is employed for the other kinematics variables. Convergence rates are studied in order to validate the finite element technique. Numerical results of the present formulation are compared with analytical and FEM solutions available in the literature. / Revisión por pares

Fossil tracks represent the only direct record of behaviour and locomotion of extinct animals. A computer model using finite element analysis (FEA) has been developed to simulate vertebrate track formation in cohesive substrates. This model has been designed for, and successfully run on, high performance computing (HPC) resources. A number of individual studies were carried out using the computer model to simulate both abstract indenters and virtual dinosaur autopodia. In addition to the simulation studies, two fossil tracks were described, including the first report of bird tracks at the Mammoth Site of Hot Springs, South Dakota (USA) and a re-description of a 'dinosaur tail drag' as the trace of a crocodilian. Using the computer model, it has been shown that in a wet, soft mud the indentation of a non-webbed virtual tridactyl foot created a resultant track with features analogous to 'webbing' between digits. This 'webbing' was a function of sediment deformation and subsequent failure in 3D, specific to rheology. Apparent webbing impressions were clearly developed only within a limited range of sediment conditions and pedal geometry. Indenter (pedal) geometry and morphology affect track depth independently of substrate and loading parameters. More complex morphologies interact with the cohesive substrate creating a lower effective load than that applied. In non-cohesive substrates such as sand, this effect is reversed, and it is the more compact morphologies that indent to a lesser degree. Virtual sauropod tracks were modelled, based on published soft tissue reconstructions of autopodia anatomy, and published mass/centre of mass estimates. It was shown that foot morphology and differential loading between fore- and hind- limbs leads to a range of substrates in which only the manus or pes are able to generate tracks. This offers a new mechanism for the formation of manus-only sauropod trackways, previously interpreted as having been made by swimming dinosaurs. A series of tracks were simulated using input data (loads, pedal morphologies) from four different dinosaurs (Brachiosaurus, Tyrannosaurus, Struthiomimus, and Edmontosaurus). The cohesive substrates used displayed a 'Goldilocks' effect, allowing the formation for tracks only for a very limited range of loads for any given foot. In addition, there was a strong bias toward larger animals, both in homogeneous and theoretically heterogeneous substrates. These findings imply that interpretations from track assemblages must consider that only a small proportion of the total fauna present may be recorded as a track assemblage due to substrate properties. The use of FEA to simulate dinosaur track formation has been shown to be successful, and offers a number of advantages over physical modelling including; consistency between experiments, specific control over input variables, rapid undertaking of repeatable experiments, and the ability to view subsurface deformation non-destructively. It is hoped that this work will lead to an increased interest in modelling tracks, and offer a quantitative method for studying fossil tracks.

Published Article / The simulation of an exhaust manifold's thermal behaviour is an important concern for various reasons. Amongst them is the need to minimise catalyst light-offtime as significant exhaust emissions are generated within this period. Modelling such behaviour is not simplistic as it is governed by complex interactions between exhaust gas flow and the manifold itself. Computational fluid dynamics (CFD) is a powerful tool for such simulations. However its applicability for transient simulations is limited by high central processing unit (CPU) demands. The present study proposes an alternative computational method to assess and rank the relative impact of the manifold's thermal properties on its exterior temperature. The results show that stainless steel manifolds potentially minimise heat loss from the exhaust gas when compared with their cast iron counterparts. This may result in an increase in thermal energy being available to heat the catalyst.

The present paper studied the buckling phenomena of membranes under tensile load with and without central crack.  The studies of fracture mechanics are tested within certain conditions of membranes. The tensile test has been performed with Al-foil in different crack lengths, i.e. 0 mm, 12.5 mm, 25 mm and 50 mm. The numerical analysis has been carried out by Finite Element Analysis (FEA) and comparing with the theoretical and experimental results.  In this paper, the critical buckling behavior is tested, validated and compared. Same observation of patterns in experiments and the simulation are found. The influence of scale factor for imperfection setting are tested.

<p>Due to the slender geometries of aboveground storage tanks, maintaining the stability under wind gusts of these tanks has always been a challenge. Therefore, this thesis aims to provide a through insight on the behavior of tanks under wind gusts using finite element analysis and computational fluid dynamic (CFD) analysis. The present thesis is composed of three independent studies, and different types of analysis were conducted. In Chapter 2, the main purpose is to model the wind loading dynamically and to investigate whether a resonance can be triggered. Research on tanks subjected to static wind load have thrived for decades, while only few studies consider the wind loading dynamically. Five tanks with different height (<i>H</i>) to diameter (<i>D</i>) ratios, ranging from 0.2 to 4, were investigated in this chapter. To ensure the quality of the obtained solution, a study on the time step increment of an explicit dynamic analysis, and a on the mesh convergence were conducted before the analyses were performed. The natural vibration frequencies and the effective masses of the selected tanks were first solved. Then, the tanks were loaded with wind gusts with the magnitude of the pressure fluctuating at the frequency associating with the most effective mass and other frequencies. Moreover, tanks with eigen-affine imperfections were also considered. It was concluded that resonance was not observed in any of these analyses. However, since the static buckling capacity and the dynamic buckling capacity has a relatively large difference for tall tanks (<i>H</i>/<i>D </i>≥ 2.0), a proper safety factor shall be included during the design if a static analysis is adopted. </p> <p> </p> <p>Chapter 3 focus on the effect of an internal pressure generated by wind gusts on open-top tanks. Based on boundary layer wind tunnel tests (BLWT), a significant pressure would be generated on the internal side of the tank shell when a gust of wind blow through an open-top tank. This factor so far has not been sufficiently accounted for by either ASCE-7 or API 650, despite the fact that this internal pressure may almost double the design pressure. Therefore, to investigate the effect of the wind profile along with the internal pressure, multiple wind profiles specified in different design documents were considered. The buckling capacities of six tanks with aspect ratios (<i>H</i>/<i>D</i>) ranging from 0.1 to 4 were analyzed adopting geometrically nonlinear analysis with imperfection using an arc-length algorithm (Riks analysis). Material nonlinearity was also included in some analyses. It was observed that the buckling capacity of a tank obtained using ASCE-7/API 650 wind profile is higher than buckling capacities obtained through any other profiles. It was then concluded that the wind profile dictated by the current North American design documents may not be conservative enough and may need a revision. </p> <p> </p> <p>Chapter 4 investigates how CFD can be applied to obtain the wind pressure distribution on tanks. Though CFD has been widely employed in different research areas, to the author’s best knowledge, only one research has been dedicated to investigate the interaction between wind gusts and tanks using CFD. Thus, a literature review on the guideline of selecting input parameter for CFD and a parametric study as how to choose proper input parameters was presented in Chapter 4. A tank with an aspect ratio of 0.5 and a flat roof was employed for the parametric study. To ensure the validity of the input parameters, the obtained results were compared with published BLWT results. After confirming that the selected input parameters produces acceptable results, tanks with aspect ratio ranging from 0.4 to 2 were adopted and wind pressure distribution on such tanks were reported. It was concluded that the established criteria for deciding the input parameters were able to guarantee converged results, and the obtained pressure coefficients agree well with the BLWT results available in the literature. </p>

<p>This Master’s thesis is summery of a comparative study of 2 commercial CAD-integrated</p><p>FE-programs. These FE-programs were CATIA v5 and ABAQUS 6.3-7. The primary</p><p>objective of this study is to investigate the basic FEA capabilities of CATIA and</p><p>ABAQUS 6.7-3 in performing the linear static analysis and to identify whether there are</p><p>any differences and similarities between results the both Finite Element FE codes give.</p><p>The overall research question in the present thesis is: Do different FE programs, here</p><p>CATIA and ABAQUS, give the same results for FE analysis giving the same models if</p><p>subjected to the same boundary conditions? This research seeks to achieve its aims</p><p>through making a comparative qualitative study. Certain pre-selections were performed in</p><p>advance of conducting Finite element analysis and the comparison process to ensure that</p><p>results would reflect only the most relevant and meaningful differences and similarities</p><p>between the both FE-codes. Five different 3D solid models have been selected to perform</p><p>linear static Finite element analysis on. All these models (case studies) are created in</p><p>CATIA V5 and the linear static analysis conducted on using FE-codes CATIA v5 and</p><p>ABAQUS 6.7-3. Three static responses (results) of the linear static analysis have been</p><p>adopted as criteria for comparisons purposes. These criteria were: (1) displacements, (2)</p><p>Von Mises stress, and (3) principal stress. The results of comparisons showed that there is</p><p>a very good agreement in most cases and small gap between in a few cases. Results of</p><p>this study demonstrate that the both FE-programs CATIA v5 and ABAQUS 6.7-3 have</p><p>good capabilities to perform FE-analysis and they give very near results. Reason behind</p><p>differences is that each of them uses a different algorithm for solving problems. The final</p><p>answer for the research question is given with valuable recommendations for future work</p><p>in the scope of this research.</p>

Many different Flexible AC Transmission System (FACTS) devices have been studied in recent years in order to control the flow of power through transmission lines and reduce the overall burden on the power grid. The net results of these devices are decreased utility costs, increased system stability, and improved system flexibility. The main issues with most currently available FACTS controllers are the high costs of installation, and operation. The Sen Transformer (ST) is a new FACTS device that decreases these costs by using relatively inexpensive and industry familiar transformer technology to independently control the active and reactive power in a transmission line.<p> This thesis introduces the first full transient model for the ST developed in an ElectroMagnetic Transients Program (EMTP) using a hybrid transformer modeling approach. This technique handles all the non-linearities of the core, including losses and saturation effects, as well as inter-phase coupling, and zero sequence effect with an attached topographically correct core model. This new model can be used in a variety of power system studies such as transient and dynamic simulations, and protection analysis. The flexibility of the hybid ST model allows for different core and winding configurations as well as response to very fast transients with little modification. Fault analysis studies are presented to showcase the capabilities of the transient ST model developed.<p> The first ST transient model using the Finite Element Analysis (FEA) technique is also created for comparison with the hybrid ST model. This method uses Maxwells equations, material non-linearities and coupled electric circuits to obtain a precise transient solution for the ST. There is good agreement between the two models in a test system for multiple types of fault scenarios. The hybrid ST model is therefore the preferred model to use for fault analysis since it reduces simulation time drastically when compared to the FEA ST model.<p> The hybrid ST model is then used to develop and test differential, and ground protection schemes that ensure device safety during faulted scenarios. The protection schemes are analyzed and compared with analogous Phase Angle Regulator (PAR) schemes that have been implemented for many years.

Diffraction Enhanced X-ray Imaging (DEI) uses synchrotron X-ray beams prepared and analyzed by perfect single crystals to achieve imaging contrast from a number of phenomena taking place in an object under investigation. The crystals used in DEI for imaging requires high precision positioning due to a narrow rocking curve. Typically, the angular precision required should be on the order of tens of nanoradians.<p>One of the problems associated with DEI is the inability to control, set, and fix the angle of the analyzer crystal in relation to the beam exiting the monochromator in the system. This angle is used to interpret the images acquired with an object present and the usual approach is to determine where the image was taken after the fact. If the angle is not correct, then the image is wasted and has to be retaken. If time or dose is not an issue, then retaking the image is not a serious problem. However, since the technique is to be developed for live animal or eventually human imaging, the lost images are no longer acceptable from either X-ray exposure or time perspectives.<p>Therefore, a mechanical positioning system for the DEI system should be developed that allows a precise setting and measurement of the analyzer crystal angles. In this thesis, the fundamental principles of the DEI method, the DEI system at the National Synchrotron Light Source (NSLS) and the sensitivity of the DEI system to vibration and temperature has been briefly studied to gain a better understanding of the problem. The DEI design at the NSLS was analyzed using finite element analysis software (ANSYS) to determine the defects in the current design which were making the system dimensionally unstable. Using the results of this analysis, the new analyzer support was designed aiming to eliminate the problems with the current design. The new design is much stiffer with the natural frequency spectrum raised about eight times. <p> This new design will improve the performance of the system at the National Synchrotron Light Source (NSLS) of Brookhaven National Laboratory, New York, USA and should assist in the development of a new DEI system for the Bio-Medical Imaging and Therapy (BMIT) beamline at the Canadian Light Source (CLS), Saskatoon, CANADA.

Many different Flexible AC Transmission System (FACTS) devices have been studied in recent years in order to control the flow of power through transmission lines and reduce the overall burden on the power grid. The net results of these devices are decreased utility costs, increased system stability, and improved system flexibility. The main issues with most currently available FACTS controllers are the high costs of installation, and operation. The Sen Transformer (ST) is a new FACTS device that decreases these costs by using relatively inexpensive and industry familiar transformer technology to independently control the active and reactive power in a transmission line.<p> This thesis introduces the first full transient model for the ST developed in an ElectroMagnetic Transients Program (EMTP) using a hybrid transformer modeling approach. This technique handles all the non-linearities of the core, including losses and saturation effects, as well as inter-phase coupling, and zero sequence effect with an attached topographically correct core model. This new model can be used in a variety of power system studies such as transient and dynamic simulations, and protection analysis. The flexibility of the hybid ST model allows for different core and winding configurations as well as response to very fast transients with little modification. Fault analysis studies are presented to showcase the capabilities of the transient ST model developed.<p> The first ST transient model using the Finite Element Analysis (FEA) technique is also created for comparison with the hybrid ST model. This method uses Maxwells equations, material non-linearities and coupled electric circuits to obtain a precise transient solution for the ST. There is good agreement between the two models in a test system for multiple types of fault scenarios. The hybrid ST model is therefore the preferred model to use for fault analysis since it reduces simulation time drastically when compared to the FEA ST model.<p> The hybrid ST model is then used to develop and test differential, and ground protection schemes that ensure device safety during faulted scenarios. The protection schemes are analyzed and compared with analogous Phase Angle Regulator (PAR) schemes that have been implemented for many years.

This Master’s thesis is summery of a comparative study of 2 commercial CAD-integrated FE-programs. These FE-programs were CATIA v5 and ABAQUS 6.3-7. The primary objective of this study is to investigate the basic FEA capabilities of CATIA and ABAQUS 6.7-3 in performing the linear static analysis and to identify whether there are any differences and similarities between results the both Finite Element FE codes give. The overall research question in the present thesis is: Do different FE programs, here CATIA and ABAQUS, give the same results for FE analysis giving the same models if subjected to the same boundary conditions? This research seeks to achieve its aims through making a comparative qualitative study. Certain pre-selections were performed in advance of conducting Finite element analysis and the comparison process to ensure that results would reflect only the most relevant and meaningful differences and similarities between the both FE-codes. Five different 3D solid models have been selected to perform linear static Finite element analysis on. All these models (case studies) are created in CATIA V5 and the linear static analysis conducted on using FE-codes CATIA v5 and ABAQUS 6.7-3. Three static responses (results) of the linear static analysis have been adopted as criteria for comparisons purposes. These criteria were: (1) displacements, (2) Von Mises stress, and (3) principal stress. The results of comparisons showed that there is a very good agreement in most cases and small gap between in a few cases. Results of this study demonstrate that the both FE-programs CATIA v5 and ABAQUS 6.7-3 have good capabilities to perform FE-analysis and they give very near results. Reason behind differences is that each of them uses a different algorithm for solving problems. The final answer for the research question is given with valuable recommendations for future work in the scope of this research.