Yes / In this paper, a compact dielectric resonator antenna (DRA) with band-notched characteristics for ultra-wideband applications is presented. A comprehensive parametric study was carried out using CST Microwave Studio Suite TM 2011 to analyze and optimize the characteristics of the proposed antenna. Three shapes for the coupling slot were investigated. Simulation results show that the proposed DRA had a −10 dB impedance bandwidth of 23% from 9.97 GHz to 12.558 GHz, and a maximum gain of 7.23 dBi. The antenna had a notched band centered at 10.57 GHz, which increased the reflection coefficient by 23.5 dB, and reduced the gain by 6.12 dB. The optimized designs were verified by experimental tests on fabricated samples.

Foi realizado estudo sobre a influência da variação de alguns parâmetros do tratamento térmico de têmpera e revenimento, bem como aplicação de criogenia, na tenacidade a fratura do aço aeronáutico 300M, com a utilização da técnica de corpo cilíndrico com entalhe. Primeiramente, realizou-se a construção da curva de transição dúctil frágil, através de ensaio Charpy, para amostras submetidas a três tratamentos térmicos, 1 - Têmpera seguida de Revenimento, 2 - Têmpera seguida de criogenia e revenimento. Não foi observada influência significativa da aplicação da criogenia (tratamento de numero 2) na curva de transição dúctil-frágil em comparação com o tratamento térmico número 1. Em um segundo momento, com o auxílio da técnica de ensaio de corpo cilíndrico com entalhe, realizou-se a medição da tenacidade à fratura das amostras do aço 300M submetido a quatro diferentes tratamento térmicos, Q, V, C e D. Os tratamentos variavam entre si principalmente pela temperatura de austenitização. Os valores de dureza para as amostras submetidas a criogenia (V e D) foram maiores que as dos tratamentos sem criogenia (Q e C), e também apresentaram tenacidade à fratura menor. Com relação à temperatura de austenitização, observou-se que os tratamentos C e D, austenitizados a 980°C, propiciaram a completa dissolução de precipitados primários da matriz, elevando a tenacidade à fratura com relação aos tratamentos realizados na faixa de 870°C, Q e V, superando também os efeitos negativos para a tenacidade à fratura devido ao aumento no tamanho de grão. / This work studies the influence of the variation for some parameters on quenching and tempering heat treatment, and also deep cryogenic application, on aeronautic steel 300M fracture toughness. First, the ductile-brittle curve was constructed, by Charpy test, for samples submitted for three heat treatments, 1 Quenching and Tempering, 2 Quenching, deep cryogenic and tempering. No significant influence of deep cryogenic treatment addition (heat treatment 2) on ductile-brittle curve was observed in comparison with heat treatment 1. After that, the fracture toughness for 300M steel, submitted for heat treatments Q, V, C e D, was measured using circumferentially notched specimens technique. The main difference among these heat treatments is about austenitizing temperature. For heat treatments with deep cryogenic treatment (V and D), the hardness values were bigger than the ones without this and, analyzing fracture toughness, it was lower than the treatments without cryogenic treatment. Regarding austenitizing temperature, all heat treatments with higher austenitizing temperature at 980°C (C and D), allows complete dissolution of carbides and prior precipitates particles. Its effect was observed that this characteristic increase the fracture toughness when it is compared with others heat treatments with lower austenitizing temperature at 870°C (Q and V). This improvement is enough to overcome the grain size grown negative effects for fracture toughness.

In this thesis an experimental method to calculate cohesive characteristics for an adhesive layer in a End Notched Flexure (ENF) specimen is presented and evaluated. The method is based on the path independent J-integral where the energy release rate (ERR) for the adhesive is derived as a function of the applied forces and the rotational displacements at the loading point and at the supports of the specimen. The major advantage with the method in comparison with existing theory known by the job initiator is that it is still applicable with ENF specimens that are subjected to yielding of the adherends. The structure of this thesis is disposed so that the theory behind the J-integral method is shortly described and then an evaluation of the method is performed by aid of finite element simulations using beam and cohesive elements. The finite element simulations indicates that the ERR can be determined with good accuracy for an ENF specimen where a small scale yielding of the adherends has occurred. However when a fully cross sectional yielding of the adherends is reached the ERR starts diverging from the exact value and generates a too high ERR according to input data in the simulations, i.e. the exact values. The importance in length of the adhesive process zone is also shown to be irrelevant to the ERR measured according to the J-integral method. Simulation performed with continuum elements indicates that a more reality based FE- simulation implies a higher value of the applied load in order to create crack propagation. This is an effect of that the specimen is allowed to roll on the supports which makes the effective length between the supports shorter than the initial value when the specimen is deformed. This results in a stiffer specimen and thus a higher applied force is needed to create crack propagation in the adhesive layer. An experimental set up of an ENF specimen is created and the sample data from the experiments are evaluated with the J-integral method. For measuring the rotational displacements of the specimen which are needed for the J-integral equation an image system is developed by the author and validated by use of linear elastic beam theory. The system calculates the three rotational displacements of the specimen by aid of images taken by a high resolution SLR camera and the system for measuring the rotations may also be used in other applications than for a specific ENF geometry. The validation of the image system shows that the rotations calculated by the image system diverge from beam theory with less than 2.2 % which is a quite good accuracy in comparison with the accuracies for the rest of the used surveying equipment. The results from the experiment indicates that the used, about 0.36 mm thick SikaPower 498, adhesive has an maximum shear strength of 37.3 MPa and a critical shear deformation of 482 µm. The fracture energy is for this thickness of the adhesive is determined as 12.9 kJ/m2. This report ends with a conclusion- and a suggested future work- chapter.

A research group at University of Skövde has developed an interphase element for implementation in the commercial FE-software Abaqus. The element is using the Tvergaard & Hutchinson cohesive law and is implemented in Abaqus Explicit version 6.7 using the VUEL subroutine. This bachelor degree project is referring to evaluate the interphase element and also highlight problems with the element. The behavior of the interphase element is evaluated in mode I using Double Cantilever Beam (DCB)-specimens and in mode II using End Notch Flexure (ENF)-specimens. The results from the simulations are compared and validated to an analytical solution. FE-simulations performed with the interphase element show very good agreement with theory when using DCB- or ENF-specimens. The only exception is when an ENF-specimen has distorted elements. When using explicit finite element software the critical time step is of great importance for the results of the analyses. If a too long time step is used, the simulation will fail to complete or complete with errors. A feasible equation for predicting the critical time step for the interphase element has been developed by the research group and the reliability of this equation is evaluated. The result from simulations shows an excellent agreement with the equation when the interphase element governs the critical time step. However when the adherends governs the critical time step the equation gives a time step that is too large. A modification of this equation is suggested.

This study expands on the work of ElHajjar and HajAli (2003) on a quantitative thermoelastic strain analysis method for composite materials. Computational models for various prepreg and thicksection composites are validated with experiments using this quantitative strain analysis method. This study provides this thermomechanical calibrations for prepreg S2glass/epoxy, Carbon/epoxy, and pultruded Eglass/polyester. A research collaboration with the Institute of Paper Science and Technology (IPST) focused on infrared thermography for defect detection in wood and fibrous materials and structural systems. This study provides some detailed information on various testing setups for fiber and corrugated board systems to analyze anomalies and manufacturing defects. Quantitative infrared thermography is suggested as a preferred method for assessing the bond quality in corrugated paper systems. Methods for tracking fullfield thermal data during fatigue have been developed for FRP composites. The temperature changes on the surface of an FRP composite caused by damage during fatigue are tracked and thermoelastic stress analysis (TSA) technique is developed to relate the surface deformation to the IR emission. Infrared thermography is developed for fatigue damage detection in FRP composites with stochastic methods for analyzing this fullfield data. Future damage detection techniques in aging aircraft will require quantitative and noncontact nondestructive evaluation (NDE) methods especially for composite components. Infrared (IR) thermograpy techniques are qualitatively used to assess and indirectly infer the durability of structural systems. A research collaboration with Lockheed Martin for nondestructive evaluation of composite lap shear joints led to a development of thermoelastic stress analysis techniques for evaluation aerospace structures. Infrared thermography is used to investigate failure initiation and progression in composite lap shear joints.

Fracture toughness is an important rock property for rock fracturing and fragmentation applications. Theory and practice of opening mode (mode I) and shearing mode (mode II) fracture toughness tests are still in a developing stage for the cylindrical rock cores. A new circular plate type test specimen is used for mode II fracture toughness testing on rock cores. This involves a straight edge notched circular plate type core disc geometry under three-point bending load / new method and its associated specimen geometry is referred as straight edge notched disc bend (SNDB) specimen under three-point bending. Mode II fracture toughness results of the tests with this new geometry were compared to the results of the tests commonly employed for mode II fracture toughness testing. Specimen geometries were modeled and mode II stress intensity factors were computed by finite element modeling using ABAQUS program. For comparison purposes, mode II or shearing mode fracture toughness KIIc of two different rock types were determined by different testing methods commonly employed in recent practice. Core specimens of Ankara andesite and Afyon marble rock types were tested with cracked chevron notched Brazilian disc and cracked straight through Brazilian disc specimens under Brazilian type loading, semi-circular bend specimen and straight edge notched disc bending specimen geometries under three-point bending.For all testing groups, cylindrical cores with diameters varying from 7.5 cm to 12.5 cm were prepared with notch lengths changing from 1.5 cm to 2.6 cm. Effect of specimen thickness on mode II fracture toughness was investigated for three different testing methods. Fracture toughness values remained constant when thickness of the specimens was increased for cracked straight through Brazilian disc, semi-circular bend and straight notched disc bend methods. For cracked straight through Brazilian disc method KIIc values of Ankara andesite and Afyon marble were 0.99 MPa&radic / m and 0.86 MPa&radic / m, respectively. Mode II fracture toughness with semi-circular bend specimen was 0.43 MPa&radic / m for andesite and 0.46 MPa&radic / m for marble. When the results of the two three-point bending type tests were compared straight notched disc under three-point bending resulted in higher KIIc values (0.61 MPa&radic / m for andesite and 0.62 MPa&radic / m for marble) than the results found by semi-circular bend tests.

<p>In this thesis an experimental method to calculate cohesive characteristics for an adhesive layer in a End Notched Flexure (ENF) specimen is presented and evaluated. The method is based on the path independent J-integral where the energy release rate (ERR) for the adhesive is derived as a function of the applied forces and the rotational displacements at the loading point and at the supports of the specimen. The major advantage with the method in comparison with existing theory known by the job initiator is that it is still applicable with ENF specimens that are subjected to yielding of the adherends.</p><p>The structure of this thesis is disposed so that the theory behind the J-integral method is shortly described and then an evaluation of the method is performed by aid of finite element simulations using beam and cohesive elements. The finite element simulations indicates that the ERR can be determined with good accuracy for an ENF specimen where a small scale yielding of the adherends has occurred. However when a fully cross sectional yielding of the adherends is reached the ERR starts diverging from the exact value and generates a too high ERR according to input data in the simulations, i.e. the exact values. The importance in length of the adhesive process zone is also shown to be irrelevant to the ERR measured according to the J-integral method.</p><p>Simulation performed with continuum elements indicates that a more reality based FE- simulation implies a higher value of the applied load in order to create crack propagation. This is an effect of that the specimen is allowed to roll on the supports which makes the effective length between the supports shorter than the initial value when the specimen is deformed. This results in a stiffer specimen and thus a higher applied force is needed to create crack propagation in the adhesive layer.</p><p>An experimental set up of an ENF specimen is created and the sample data from the experiments are evaluated with the J-integral method. For measuring the rotational displacements of the specimen which are needed for the J-integral equation an image system is developed by the author and validated by use of linear elastic beam theory. The system calculates the three rotational displacements of the specimen by aid of images taken by a high resolution SLR camera and the system for measuring the rotations may also be used in other applications than for a specific ENF geometry. The validation of the image system shows that the rotations calculated by the image system diverge from beam theory with less than 2.2 % which is a quite good accuracy in comparison with the accuracies for the rest of the used surveying equipment.</p><p>The results from the experiment indicates that the used, about 0.36 mm thick SikaPower 498, adhesive has an maximum shear strength of 37.3 MPa and a critical shear deformation of 482 µm. The fracture energy is for this thickness of the adhesive is determined as 12.9 kJ/m².</p><p>This report ends with a conclusion- and a suggested future work- chapter.</p>

<p>A research group at University of Skövde has developed an interphase element for implementation in the commercial FE-software Abaqus. The element is using the Tvergaard & Hutchinson cohesive law and is implemented in Abaqus Explicit version 6.7 using the VUEL subroutine. This bachelor degree project is referring to evaluate the interphase element and also highlight problems with the element.</p><p>The behavior of the interphase element is evaluated in mode I using Double Cantilever Beam (DCB)-specimens and in mode II using End Notch Flexure (ENF)-specimens. The results from the simulations are compared and validated to an analytical solution.</p><p>FE-simulations performed with the interphase element show very good agreement with theory when using DCB- or ENF-specimens. The only exception is when an ENF-specimen has distorted elements.</p><p>When using explicit finite element software the critical time step is of great importance for the results of the analyses. If a too long time step is used, the simulation will fail to complete or complete with errors. A feasible equation for predicting the critical time step for the interphase element has been developed by the research group and the reliability of this equation is evaluated.</p><p>The result from simulations shows an excellent agreement with the equation when the interphase element governs the critical time step. However when the adherends governs the critical time step the equation gives a time step that is too large. A modification of this equation is suggested.</p>

The great innovations of the last century have ushered continuous progress in many areas of technology, especially in the form of miniaturization of electronic circuits. This progress shows a trend towards consistent decreases in power requirements due to miniaturization. According to the ITRS and industry leaders, such as Intel, the challenge of managing and providing power efficiency still persist as scaling down of devices continues. A variety of power sources can be used in order to provide power to low power applications. Few of these sources have favorable characteristics and can be designed to deliver maximum power such as the novel mini notched turbine used as a source in this work. The MiNT is a novel device that can be used as a feasible energy source when integrated into a system and evaluated for power delivery as investigated in this work. As part of this system, a maximum power point tracking system provides an applicable solution for capturing enhanced power delivery for an energy harvesting system. However, power efficiency and physical size are adversely affected by the characteristics and environment of many energy harvesting systems and must also be addressed. To address these issues, an analysis of mini notched turbine, a RF rectenna, and an enhanced maximum power point tracking system is presented and verified using simulations and measurements. Furthermore, mini notched energy harvesting system, RF rectenna energy harvesting system, and enhanced maximum power point tracking system are developed and experimental data analyzed. The enhanced maximum power point tracking system uses a resistor emulation technique and particle swarm optimization (PSO) to improve the power efficiency and reduce the physical size. This new innovative design improves the efficiency of optimized power management circuitry up to 7% compared to conventional power management circuits over a wide range of input power and range of emulated resistances, allowing more power to be harvested from small energy harvesting sources and delivering it to the load such as smart sensors. In addition, this is the first IC design to be implemented and tested for the patented mini notched turbine (MiNT) energy harvesting device. Another advantage of the enhanced power management system designed in this work is that the proposed approach can be utilized for extremely small energy sources and because of that the proposed work is valid for low emulated resistances. and systems with low load resistance Overall, through the successful completion of this work, various energy harvesting systems can have the ability to provide enhanced power management as the IC industry continues to progress toward miniaturization of devices and systems.

The purpose of this research is to design and integrate a symbiotic notched-turbine energy generator for implantation as a cross-coupled system capable of continuously and perpetually powering an electronic implantable medical device (IMD), which is a device designed to operate inside the body of a higher mammal to enhance, correct or provide the body with a function that has deviated from the norm or has stopped altogether. The list of IMDs available for implantation keeps growing every year, one of the newest being the VBLOC, produced by EnteroMedics®, and approved by the Food and Drug Administration (FDA) on January 15th, 2015[1], [2] to treat obesity in the United States, in lieu of the more dangerous and costly bariatric surgery widely used to treat the same condition. Some of the more traditional IMDs, such as the cardiac defibrillator, pacemaker, and insulin pumps require the use of a battery system for their operation. The powering of IMDs is a topic of growing importance and as such, the energy released by the hydrodynamic action of the cardiovascular system of a higher mammal is presented in this work as a source of energy that can be converted into electricity by use of a microturbine, loaded with magnetic rings that induce a time-varying magnetic field onto a set of insulated coils through the process of electromagnetic induction (EMI) in accordance with Faraday’s Law. This work goes beyond mere power production and focuses on the process required to integrate this power source with an IMD when it is coupled to the cardiovascular system for drawing hydro-mechanical power for conversion to electricity and to the IMD of choice to xii deliver the conditioned power, thus replicating a symbiotic process. The harvested energy in the form of a time-varying tri-phase sine wave is therefore rectified, conditioned and made available for use to the IMD. The proposed 3-phase generator has a volume of 1.02 cm3 and has the potential to be implemented as a dual or quad system that doubles or quadruples the single generator power capabilities accordingly. The rectifying and conditioning circuits may be housed in a hermetically sealed container, covered with a biocompatible material such as, ultra-high molecular weight polyethylene (UHMWPE), polymethylmethacrylate (PMMA) or titanium, which can afford the best implantation properties such as non-absorbability, durability, hardness, and biocompatibility [4]. Additionally, the prevention of blood clotting is of paramount importance in any IMD, which can be helped, for example by treating its surface with Tethered-Liquid Perfluorocarbons (TLP) to prevent biofilm formation of the blood that typically leads to infections and clotting[5].