<p> Foraminiferal and thecamoebian biofacies were documented in the modem Korphos marsh located on the western coast of the Saronikos Gulf, Greece in order to define the general ecological features (such as salinity and proximity to marine influence) of the environments they occupied. These constraints were later used to identify fossil biofacies in subsurface marsh sediments at Korphos. </p> <p> Positive marine tendencies identified in fossil biofacies distributions were used for the first time to radiocarbon date relative changes in sea-level implied by a series of discrete, submerged tidal notches and beach rock adjacent to the marsh along the coast. Magnitude of subsidence events based on notch and beach rock data were measured to 2.9m, 0.5m, 1.3m, 0.39m, 0.47m, and 0.34m. The relatively unaltered v-shape of each notch profile suggested that sea-level rise was rapid and episodic. </p> <p> A comparison between the tidal notches and beach rock and an isostatically corrected model of sea-level for this area isolated the tectonic contribution to sea-level change and revealed that at least four of the six sea-level indicators plotted well-below predicted sea-level during subsidence. Therefore, the gradual sea-level rise of the late Holocene was interrupted by at least four sub-meter to meter-scale, step-wise increases in relative sea-level during coseismic subsidence of the Korphos marsh. The results of this study show how the combination of geomorphological and salt-marsh records have the potential to remove errors stemming from a lack of datable material for notches and autocompaction of marsh sediments when reconstructing local sea-level change. </p> / Thesis / Master of Science (MSc)

This work investigates the area of transformable and modular clothes through the technique of notching. The idea of transformable clothes is not new. Throughout history garments have been tied, wrapped or pinned together. Transformable clothes are often seen as a sustainable option because it challenges the wearer and creates a bond making the garment more valuable. This work seeks to present a new way of draping modular clothes by pinning notching strips onto fabric, transforming it into shapes. Resulting in a collection of pieces that can be combined in many different ways, creating a large collection using a small amount of materials.

As the use of engineered wood products as such as cross-laminated timber (CLT) evolves in United States, it’s imperative to understand its behavior under different circumstances as well as to explore new possible streams for product’s application. In that matter, it was proposed that a research study would be developed to evaluate the performance of CLT panels focusing on strength and stiffness properties. To accomplish this goal, three main objectives were traced: 1) To complete preliminary test on traditional lumber in order to observe notched wood failure behavior focusing on strength, ductility, and failure mode; 2) To perform mechanical testing and non-destructive evaluation on 3-ply CLT control panels in order to compare design calculation methods and efficiency of NDE on CLT; and 3) To perform mechanical testing on notched 3-ply CLT samples to evaluate the influence of notches and stitching reinforcement on panels. Based on these objectives, this dissertation features five main sections: 1) General Introduction, 2) Technical note: Ductility and brittleness in small clear notched S-P-F beams, 3) Evaluation of the modulus of elasticity and modulus of rupture of cross-laminated timber with longitudinal vibration NDE techniques, 4) Case study of 3-ply commercial southern pine CLT mechanical properties and design values, and 5) Effect of notching on 3-ply southern pine cross-laminated timber panels stiffness and strength.

[pt] Foram determinados experimentalmente fatores de concentração de tensões teóricos para placas e eixos com entalhes simétricos e circunferenciais em U sujeitos à combinação de esforços de flexão e tração, para as placas e, flexão e torção para os eixos. Os fatores obtidos foram plotados em gráficos para comparação com fatores determinados aplicando-se o princípio da superposição. Foram utilizadas as relações geométricas D / d = 1,5; 1,25; 1,10 e r/d = 0,30; 0,25; 0,20 para as placas. Para os eixos utilizaram-se apenas as relações 0/d = 1,3 e r/d = 0,25. Também foram obtidos fatores de concentração de tensões para os esforços puros e seus valores comparados com resultados já publicados. Os resultados para as placas foram obtidos a partir da fotoelasticidade bidimensional. Foi empregado o método fotoelástico tridimensional de congelamento de tensões para os eixos. Neste caso, os modelos foram cortados em finas fatias para separação das tensões. Para o estudo tridimensional foi utilizado um material desenvolvido no laboratório de Fotomecanica da PUC-RJ. / [en] Theoretical stress concentration factors were determined experimentally for bars and shafts with symmetrical and circunferential U – shaped grooves subjected to combinations of bending – tension loads for the bars and bending – torsion loads for the shafts. The stress concentration factors obtained were plotted to compare with the factors determined by application of the superposition effects. The geometric relations used for the bars were Dd = 1,5; 1,25; 1,10 and rd = 0,30; 0,25; 0,20. The geometric relations used for the shafts were Dd = 1,3 e rd = 0,25. The stress concentration factors were also determined for single loaded specimens and they were compared wuth data already published. The stress concentration factors for the bars were determined by the two – Dimensional photoelastic method. In the case of the shafts they were determined by the three – Dimensional photoelastic Method of stress Freezing. In this method, the models developed in the laboratory of Photomechanics of the Universidade Católica.

Yes / To support various fifth generation (5G) wireless applications, a small, printed bowtie-shaped microstrip antenna with meandered arms is reported in this article. Because it spans the broad legal range, the developed antenna can serve or reject a variety of applications such as wireless fidelity (Wi-Fi), sub-6 GHz, and ultra-wideband (UWB) 5G communications due to its multiband characterization and optimized rejection bands. The antenna is built on an FR-4 substrate and powered via a 50-Ω microstrip feed line linked to the right bowtie’s side. The bowtie’s left side is coupled via a shorting pin to a partial ground at the antenna’s back side. A gradually increasing meandering microstrip line is connected to both sides of the bowtie to enhance the rejection and operating bands. The designed antenna has seven operating frequency bands of (2.43–3.03) GHz, (3.71–4.23) GHz, (4.76–5.38) GHz, (5.83–6.54) GHz, (6.85–7.44) GHz, (7.56–8.01) GHz, and (9.27–13.88) GHz. The simulated scattering parameter S11 reveals six rejection bands with percentage bandwidths of 33.87%, 15.73%, 11.71, 7.63%, 6.99%, and 12.22%, respectively. The maximum gain of the proposed antenna is 4.46 dB. The suggested antenna has been built, and the simulation and measurement results are very similar. The reported antenna is expanded to a four-element design to investigate its MIMO characteristics. / Partially funded by British Council “2019 UK-China-BRI Countries Partnership Initiative” program, with project titled “Adapting to Industry 4.0 oriented International Education and Research Collaboration.

The topic of this thesis is the investigation of the local states of stress resulting from the introduction of av-notch in a coaxial circle on the pressurized surface of a circumferentially clamped plate subject to axisymmetric loading. The understanding of the fracture behavior of a component experiencing such a condition is of particular interest to the aerospace and defense industries where circular plate components are often utilized. In such applications, it is imperative that the designer be able to predict the loading conditions facilitating dynamic fracture. As a step towards solving such problems, the quasi-static analogy is studied. Specifically, the purpose of this research is to examine and model the precise effects a stress raiser will have on the fracture behavior and strength reduction of a circular plate machined from Ultem 1000. Parametric FEM simulations were employed to determine the correlation between notch geometry and the resulting maximum stress and stress distribution in the notch root vicinity. Stress concentration factor (SCF) relationships were developed which characterize the effect individual geometric parameters have on the notch root stresses. Mathematical models were developed to provide the elastic stress concentration factor for any combination of geometric parameters within the range studied. Additionally, the stress distributions along the notch root and ahead of the notch were characterized for a variety of geometric configurations. Test coupons were employed to not only characterize the mechanical behavior of the material, but also characterize the correlation between simple and axisymmetric loading, respectively. The development of a predictive approach for designers of such circular components to be able to accurately determine the fracture behavior of these components was the motivating factor of this study.

Geomorphic features have been one of the major tools for sea-level change studies. The present work shows an example of sea-level change study on karst terrain in the tropics. Sea-level notches as well as flank margin caves were identified in the research area and their elevation measured. The time of formation of the sea-level indicators was constrained by lithology study and dating methods such as facies comparison and U-Th dating. Denudation and uplift were also studied for the same purpose. From this study it can be concluded that sea-level stands within the glacial cycle can cause the formation of flank margin caves and that the position of these sea-level stands can be determined. The research area was estimated to have cumulatively uplifted ~22 m in the past 125 ka years (~0.18 mm/yr) while the surface has been denuded some 8 m in the same span of time (~0.064 mm/yr).

Die Arbeit untersucht den Einfluss von von radialen, im Zahngrund auslaufenden Schmierölbohrungen auf die Zahnfußtragfähigkeit außenverzahnter Stirnräder durch theoretische und experimentelle Untersuchungen. Es werden Formeln entwickelt, die ohne zeitaufwändige Berechnungen eine sichere Beurteilung des Einflusses von Schmierölbohrungen auf die Zahnfußtragfähigkeit ermöglichen. Dazu wird ein Einflussfaktor Y_OeB ermittelt, welcher die einfache Integration in vorhandene Berechnungsstandards erlaubt. Als Vorlage dient dabei die Berechnung der Zahnfußtragfähigkeit nach DIN 3990 / ISO 6336, die durch diesen Faktor ergänzt werden kann. Neben experimentellen Versuchen zum Einfluss der geometrischen Größen Zahnfußausrundungsradius und Bohrungsdurchmesser werden auch verschiedene Parameter wie die Kranzdicke, zusätzliche Torsionsbelastungen (z. B. an Sonnenwellen), die Wärmebehandlung und die Belastungsart (Schwell- oder Wechsellast) berücksichtigt. Darüber hinaus betrachtet die Arbeit das Verhalten verschiedener Werkstoffe bei Vorhandensein einer Schmierölbohrung. Sie liefert des Weiteren einen Erklärungsansatz zum Einfluss der Schmierölbohrungen auf die Zahnfußtragfähigkeit auf Basis der Veränderung der Eigenspannungsverteilung im Zahnfußgebiet durch die radiale Bohrung und bietet dafür auch ein Modell zur qualitativen Berechnung der Eigenspannungsverteilung auf Basis der FE-Methode an.

Directionally solidified (DS) nickel-base superalloys are used in high temperature gas turbine engines because of their high yield strength at extreme temperatures and strong low cycle fatigue (LCF) and creep resistance. Costly inspecting, servicing, and replacing of damaged components has precipitated much interest in developing models to better predict service life. Turbine blade life modeling is complicated by the presence of notches, dwells, high temperatures and temperature gradients, and highly anisotropic material behavior. This work seeks to develop approaches for predicting the life of hot sections of gas turbines blade material CM247LC DS subjected to LCF, dwells, and stress concentrations while taking into consideration orientation and notch effects. Experiments were conducted on an axial servo-hydraulic MTS® testing machine. High temperature LCF tests were performed on smooth and notched round-bar specimens in both longitudinal and transverse orientations with and without dwells. Experimental results were used to develop and validate an analytical life prediction model. An analytical model based on a multiaxial Neuber approach predicts the local stress-strain response at a notch and other geometric stress concentrations. This approach captures anisotropy through a multiaxial generalization of the Ramberg-Osgood relation using a Hill's type criterion. The elastic notch response is determined using an anisotropic elastic finite element analysis (FEA) of the notch. The limitations of the simpler analytical life-modeling method are discussed in light of FEA using an anisotropic elastic-crystal viscoplastic material model. This life-modeling method provides a quick alternative to time demanding elastic-plastic FEA allowing engineers more design iterations to improve reliability and service life.

Die Arbeit untersucht den Einfluss von von radialen, im Zahngrund auslaufenden Schmierölbohrungen auf die Zahnfußtragfähigkeit außenverzahnter Stirnräder durch theoretische und experimentelle Untersuchungen. Es werden Formeln entwickelt, die ohne zeitaufwändige Berechnungen eine sichere Beurteilung des Einflusses von Schmierölbohrungen auf die Zahnfußtragfähigkeit ermöglichen. Dazu wird ein Einflussfaktor Y_OeB ermittelt, welcher die einfache Integration in vorhandene Berechnungsstandards erlaubt. Als Vorlage dient dabei die Berechnung der Zahnfußtragfähigkeit nach DIN 3990 / ISO 6336, die durch diesen Faktor ergänzt werden kann. Neben experimentellen Versuchen zum Einfluss der geometrischen Größen Zahnfußausrundungsradius und Bohrungsdurchmesser werden auch verschiedene Parameter wie die Kranzdicke, zusätzliche Torsionsbelastungen (z. B. an Sonnenwellen), die Wärmebehandlung und die Belastungsart (Schwell- oder Wechsellast) berücksichtigt. Darüber hinaus betrachtet die Arbeit das Verhalten verschiedener Werkstoffe bei Vorhandensein einer Schmierölbohrung. Sie liefert des Weiteren einen Erklärungsansatz zum Einfluss der Schmierölbohrungen auf die Zahnfußtragfähigkeit auf Basis der Veränderung der Eigenspannungsverteilung im Zahnfußgebiet durch die radiale Bohrung und bietet dafür auch ein Modell zur qualitativen Berechnung der Eigenspannungsverteilung auf Basis der FE-Methode an.:1 EINLEITUNG 1 1.1 WISSENSCHAFTLICHE PROBLEMSTELLUNG 1 1.2 ZIELSETZUNG 1 2 STAND DER TECHNIK UND DER BISHERIGEN FORSCHUNG 3 2.1 KERBEN UND KERBWIRKUNG 3 2.1.1 Einzelkerben 3 2.1.2 Mehrfachkerben 4 3 PRÄZISIERUNG DER AUFGABENSTELLUNG 6 4 NUMERISCHE UNTERSUCHUNGEN DER ZAHNRÄDER 7 4.1 GRUNDLAGEN DER FINITE ELEMENTE METHODE 7 4.2 FEM-MODELLBILDUNG – ELEMENTTYPEN 8 4.3 PARAMETERSTUDIE – GRUNDLEGENDE UNTERSUCHUNGEN 10 4.3.1 Variation der Umfangslage der Bohrung 17 4.3.2 Zusammenfassung der Parametervariationen 19 4.4 UNTERSUCHUNGEN ZUM EINFLUSS DER ZAHNBREITE 22 4.5 UNTERSUCHUNG DES SPANNUNGSGRADIENTEN 23 4.6 EINFLUSS EINER FASE AM AUSLAUF DER BOHRUNG IM ZAHNGRUND 25 4.7 SCHMIERÖLBOHRUNG UND VERZAHNUNGSMODIFIKATIONEN 27 5 EXPERIMENTELLE UNTERSUCHUNGEN 28 5.1 ALLGEMEINE VORBEMERKUNGEN 28 5.1.1 Versuchsvorrichtung für Schwelllastversuche 30 5.1.2 Prüfvorrichtung für Wechsellastversuche 31 5.2 KONTROLLE DER BREITENLASTVERTEILUNG 33 5.2.1 Lastverteilung am Zahnkopf 34 5.2.1.1 2D-Kontaktrechnung – Ermittlung des Hebelarmes unter Last 35 5.2.1.2 3D-Kontaktrechnung – Breitenlastverteilung am Zahnkopf 36 5.3 AUSWERTUNG DER VERSUCHE 38 5.3.1 Zeitfestigkeitsgebiet 38 5.3.1 Dauerfestigkeitsgebiet 39 5.4 ERGEBNISSE DER EXPERIMENTELLEN UNTERSUCHUNGEN 42 5.4.1 Geometrievariationen 42 5.4.2 Untersuchung anderer Parameter 43 5.4.3 Einfluss des Werkstoffes 47 5.4.4 Ergebnisse der Wechsellastversuche 51 5.5 STREUUNG DER MESSERGEBNISSE 53 5.6 ERGEBNISSE DER WERKSTOFFTECHNISCHEN UNTERSUCHUNGEN 54 5.6.1 Ergebnisse für 18CrNiMo7-6 54 5.6.2 Ergebnisse für 16MnCr5 55 5.6.3 Ergebnisse für 42CrMo4 55 5.6.4 Ergebnisse für 31CrMoV9 55 5.6.5 Untersuchung des Bruchbildes 56 5.7 UNTERSUCHUNG DES EIGENSPANNUNGSZUSTANDES 57 5.7.1 Experimentelle Untersuchungen 57 5.7.2 Theoretische Untersuchung der Verteilung der Eigenspannungen 60 5.7.2.1 Ringmodell 62 5.7.2.2 L-Modell 66 5.7.2.3 Zahnlückenmodell 70 5.7.2.4 Zahnradsegmentmodell 73 6 ZUSAMMENFASSUNG 77 7 AUSBLICK 80 8 LITERATUR 84 9 ABBILDUNGSVERZEICHNIS 89 10 TABELLENVERZEICHNIS 91 11 ANHANG 92