Thesis (M.A.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

abstract: Ultra-concealable multi-threat body armor used by law-enforcement is a multi-purpose armor that protects against attacks from knife, spikes, and small caliber rounds. The design of this type of armor involves fiber-resin composite materials that are flexible, light, are not unduly affected by environmental conditions, and perform as required. The National Institute of Justice (NIJ) characterizes this type of armor as low-level protection armor. NIJ also specifies the geometry of the knife and spike as well as the strike energy levels required for this level of protection. The biggest challenges are to design a thin, lightweight and ultra-concealable armor that can be worn under street clothes. In this study, several fundamental tasks involved in the design of such armor are addressed. First, the roles of design of experiments and regression analysis in experimental testing and finite element analysis are presented. Second, off-the-shelf materials available from international material manufacturers are characterized via laboratory experiments. Third, the calibration process required for a constitutive model is explained through the use of experimental data and computer software. Various material models in LS-DYNA for use in the finite element model are discussed. Numerical results are generated via finite element simulations and are compared against experimental data thus establishing the foundation for optimizing the design. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2012

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.

O carbeto de boro é um material sintético com ligações químicas essencialmente covalentes, tem um alto ponto de fusão só é sinterizável em elevada temperatura. Possui excepcional dureza, baixa densidade, resistência a abrasão, elevada velocidade sônica e boas propriedades mecânicas, características ideais para as aplicações balísticas. Tem como principal característica a alta seção de choque para nêutrons térmicos para aplicações nucleares. O presente trabalho teve por objetivo avaliar as propriedades mecânicas do carbeto de boro, pela introdução de diferentes teores de diboreto de titânio, pela reação in situ com pós de carbeto de titânio, e adição do carbono durante a sinterização, em forno resistivo sem pressão e prensagem isostática a quente dos componentes cerâmicos. Em menores temperaturas valores obtidos da densidade teórica para o carbeto de boro puro, foram alcançados com o emprego do aditivo. Os resultados obtidos na sinterização mostram a eficiência da introdução do carbeto de titânio para o aumento da densificação do material. Com percentuais de 20% de carbeto de titânio, obteve-se os máximos valores para microdureza (HV) de 35 GPa e tenacidade a fratura (KlC) de 3,16 MPa.m1/2. Comprovadamente a dificuldade de sinterização em elevadas temperaturas, para maior densificação, de componentes cerâmicos de carbeto de boro pode ser minimizada com a introdução de percentuais de carbeto de titânio. / Boron Carbide is a synthetic material with essentially covalent chemical bonds with high fusion point. The main characteristics are: it is sintered at high temperature, high hardness, low density, abrasion resistant, high sonic velocity, good mechanical properties and high neutron absorption cross section (10BxC, x>4). Those features are ideal for ballistics applications. The aim of this study was to evaluate the changes in mechanical properties of Boron Carbide with different concentration of Titanium Diboride by reaction in situ with TiC powders. The addition of carbon during sintering without pressure and hot isostatic pressing of ceramic components was studied. At low temperatures, the nearly values for the theoretical density for pure Boron Carbide were obtained only with the use of additives. In sintering, the use of TiC increased Boron Carbide density. At concentrations up to 20% of TiC, the maximum values for hardness (HV) and fracture toughness (KlC) were obtained. With the introduction of different levels of additive, the difficulty of sintering at high temperatures was minimized and the density of ceramic components was maximized.

No description available.

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.

The Full Armor of God is a musical composition based on the apostle Paul's comparison in Ephesians 6:10-20 between armor for physical combat and armor for spiritual warfare. The instrumentation consists of the following: oboe/English horn, bassoon, two violins, viola, cello, and bass. Texts on Roman armor as well as commentaries and sermons on the scriptures were consulted for the basis of the musical materials. The piece combines imagery and historical associations with abstract renderings of both the physical and the spiritual.

Shear thickening fluids have the potential to improve the effectiveness of fabric materials in body armor applications as they have shown to increase the puncture and ballistic resistance of Kevlar fabrics. However, the effect of using STFs with natural fabrics such as flax has never been studied. The rheology of STFs at varying concentrations of nanosilica dispersed in polyethylene glycol PEG was studied at different temperatures and it was found that the STFs behave as a non-Newtonian fluid in response to changes in shear rate. In this study the effectiveness on the puncture and ballistic resistance of impregnating flax fabric with STF of nanosilica in PEG were investigated. The effect of hybridization of flax and Kevlar was also investigated. The puncture and ballistic resistance of the samples treated with STFs was found to increase significantly and can be controlled by STF concentration.

Sintering parameter effects on the microstructure of boron carbide and boron carbide/titanium diboride composites are investigated. The resulting microstructure and composition are characterized by scanning electron microscopy (SEM), x-ray microscopy (XRM) and x-ray diffraction (XRD). Starting powder size distribution effects on microstructure are present and effect the mechanical properties. Reactive spark plasma sintering introduces boron nitride (BN) intergranular films (IGF's) and their effects on fracture toughness, hardness and flexural strength are shown. Mechanical testing of Vickers hardness, 3-point bend and Chevron notch was done and the microstructural effects on the resulting mechanical properties are investigated.

Modified rolled homogeneous armor (RHA) steels were designed and produced to characterize the effects of niobium additions and accompanying heat treatments on microstructure and mechanical properties. This study combines in-house steel production and property analysis to advance the understanding of niobium on enhanced hardenability and weldability in a chemistry-process-structure-property relationship paradigm. For steel production, designed alloys were cast in a vacuum induction melting furnace and thermo-mechanically processed. Optimal heat treatment conditions were determined by utilizing a thermo-mechanics calculation software. Microstructures were investigated by optical and electron microscopy while hardenability was characterized by Jominy end-quench tests. Mechanical tests were performed at various stress states, strain rates, and temperatures to understand deformation behavior under complex loading conditions. Encouraging results in performance were observed in the micro-alloyed armor steels as compared to reference materials from earlier studies.