Finite Element Modeling of Ballistic Impact on a Glass Fiber Composite Armor Dan Davis Experiments measuring the ballistic performance of a commercially available fiberglass armor plate were used to guide the development of constitutive laws for a finite element model of the impact. The test samples are commercially available armor panels, made from E-glass fiber reinforced polyester rated to NIJ level III. Quasi-static tensile tests were used to establish material properties of the test panels. These properties were then used to create models in the explicit finite element code LSDYNA. Ballistic impact testing of the panels was conducted using a compressed gas gun firing spherical steel projectiles oriented normal to the test panel surface. The V50 ballistic limit of these panels was found to be approximately 560 m/s. Tuning parameters in the finite element models were adjusted to match the experimentally measured penetration depths and ballistic limits. Models were created in LSDYNA by adjusting the available material library types 3 and 59 for the target, and material type 15 for the projectile. Type 3 models are isotropic, and resulted in shear punch-out type failures of the plate that poorly replicated the test results. Type 59 takes orthotropic properties into consideration, and can analyze delamination when used with solid elements. Results with model type 59 were significantly better than those using type 3, however, this model was found to vastly underestimate the impact resistance of the plate. With significant adjustments to the material properties in the type 59 model, the LSDYNA simulations were found to better replicate the experimentally observed response of the panels. However, these deformations are questionable since they required quite unrealistic adjustments to the material properties.

No description available.

Terminal ballistics study multivariate behavior and aftermath of projectile and target interactions. Tests and models are often based on monolithic armors, however, layered and spaced armors are common in real world applications. Such configurations add complexities that require research to understand their effects on terminal ballistics. The ballistic limit velocity (V50) represents the speed where armor perforation probability is 50%. It is used for quantitative comparison of protection capabilities for different armors. This research studied the V50 of spaced and layered A36 steel armors against fragment simulating projectiles (FSPs). Four methods for estimating armor V50 were evaluated and compared to experimental data. The first two methods were analytical methods from literature, the third was finite element (FE) simulations in EPIC, and the fourth was a Monte Carlo method developed in this research. The Monte Carlo method using 100,000 iterations was the most accurate and efficient of all methods.

No description available.

The design of rubble mound breakwaters usually focuses on the main armor layer. A review of the existing literature reveals that different equations are used to design rock armors in non-breaking wave conditions. However, most rubble mound breakwaters are constructed in the depth-induced breaking zone where they are attacked by waves breaking in the foreshore; in these conditions, existing design equations are not valid. Therefore, in this PhD thesis, the hydraulic stability of double-layer rock armors is analyzed through a series of small-scale tests conducted with a bottom slope m=1/50. Based on test results, a new potential relationship is given to design rock armors in depth-limited breaking wave conditions with armor slope cot¿=1.5, stability numbers within the range 0.98¿Hm0/(¿Dn50)¿2.5, and relative water depth at the toe 3.75¿hs/(¿Dn50)¿7.50. When concrete units are used for the armor layer, mound breakwaters are usually protected by a toe berm. This toe berm is placed on the seafloor or underlayer, providing support for the concrete armor units which are placed later on the structure slope. Toe berm design is commonly related to the armor design; in non-breaking wave conditions, the mass of toe berm rocks is one order of magnitude lower than the units of the layer. In breaking wave conditions, however, the highest waves start breaking on the bottom and impact directly on the toe berm. This is the common case of rocky sea bottoms with m=1/10 or higher slopes and thus, a correct design of the toe berm is crucial to guarantee the armor stability. The present PhD thesis examines the hydraulic stability of rock toe berms placed on a m=1/10 bottom slope and in very shallow waters (0.5<hs/Dn50<5.01). Small-scale tests were conducted with double-layer cube armored breakwaters and rock toe berms with different widths (Bt) and thicknesses (tt). Firstly, a new equation is proposed to design emerged and submerged standard rock toe berms (Bt=3Dn50 and tt=2 Dn50) using three parameters: (1) deep water wave height, Hs0, (2) deep water wave length, L0p, and (3) water depth at the toe, hs. Secondly, the influence of toe berm width (Bt) on toe berm stability is analyzed introducing two new concepts to characterize wide toe berms (Bt>3Dn50): (1) the nominal toe berm or the most shoreward toe berm area which effectively supports the armor layer, and (2) the sacrificial toe berm or the most seaward toe berm area which serves to protect the nominal toe berm. Considering the nominal toe berm damage, a new method is developed to reduce the rock toe berm size (Dn50) by increasing the toe berm width (Bt) if the required rock size is not available at the quarries. Finally, cube armor damage is examined, and the influence of the placement technique on armor stability is also characterized from physical tests conducted with cubes randomly- and uniformly- placed on the armor in two layers. / El manto principal de los diques en talud suele estar formado por escollera natural o elementos prefabricados de hormigón; su función es resistir la acción del oleaje. Una revisión del estado del arte pone de manifiesto que son numerosas las fórmulas existentes para el diseño de mantos derivadas de ensayos físicos a escala reducida con oleaje sin rotura por fondo. Sin embargo, la mayoría de diques en talud se construyen en la zona de rompientes con oleaje limitado por fondo, donde las ecuaciones de diseño habituales no son del todo válidas. En esta tesis doctoral se analiza la estabilidad hidráulica de mantos bicapa de escollera, a partir de ensayos a escala reducida con pendiente de fondo m=1/50. En base a los resultados obtenidos de los ensayos físicos, se propone una nueva relación potencial para el diseño de mantos de escollera en condiciones de oleaje limitado por fondo, válida para taludes con cot¿=1.5, números de estabilidad 0.98¿Hm0/(¿Dn50)¿2.5, y profundidades relativas a pie de dique de 3.75¿hs/(¿Dn50)¿7.50. Cuando el manto principal está formado por elementos de hormigón, es habitual construir una berma de pie que proporciona apoyo a los elementos del manto y, en su caso, colabora en la protección de la zona inferior del dique contra la socavación. Dicha berma suele construirse con escollera natural y su peso está condicionado al de los elementos del manto en el caso de no haber rotura por fondo. El peso de los elementos de la berma de pie suele ser un orden de magnitud inferior al peso de las unidades del manto; sin embargo, si la pendiente de fondo es fuerte (p.e. m=1/10) y las aguas someras esta regla no se cumple ya que algunas olas rompen sobre el fondo impactando directamente sobre la berma de pie. En estos casos, el peso de la escollera de la berma puede sobrepasar el de las unidades del manto y su correcto diseño es crucial para garantizar la estabilidad del dique. Además de estudiar la estabilidad del manto principal de diques de escollera, la presente tesis doctoral analiza también la estabilidad hidráulica de bermas de pie de escollera ubicadas en fondos con pendiente m=1/10 y aguas someras (0.5<hs/Dn50<5.01), en base a ensayos físicos a escala reducida realizados con mantos bicapa de cubos y bermas de escollera con diferentes dimensiones. En primer lugar, se propone una nueva ecuación para el diseño de bermas escollera estándar (Bt=3Dn50 y tt=2 Dn50), tanto emergidas como sumergidas, a partir de tres parámetros: (1) altura de ola en aguas profundas, Hs0, (2) longitud de onda en aguas profundas, L0p, (3) profundidad a pie de dique, hs. Posteriormente, se analiza la influencia del ancho de la berma (Bt) en su estabilidad hidráulica, introduciendo dos nuevos conceptos para caracterizar bermas de pie anchas (Bt>3Dn50): (1) berma nominal o zona de la berma de pie sobre la que realmente apoya el manto principal, y (2) berma de sacrificio o zona de la berma de pie que protege a la berma nominal. A partir del daño de la berma de pie nominal, se propone un nuevo método para reducir el tamaño de piedra (Dn50) incrementando el ancho de la berma (Bt) cuando no se disponga del tamaño requerido en cantera. Finalmente, se examina el daño del manto de cubos y se analiza la influencia del método de colocación sobre el mismo, a partir de ensayos realizados con mantos bicapa de cubos con colocación aleatoria y uniforme. / El mantell principal dels dics en talús sol estar format per roca o elements prefabricats de formigó, la seva funció és resistir l'acció de l'onatge. Una revisió de l'estat de l'art manifesta que són nombroses les equacions de disseny existents per a condicions d'onatge no trencat. No obstant això, la majoria de dics en talús es construeixen a la zona de rompents amb onatge limitat per fons, on les equacions de disseny existents no són del tot vàlides. En aquesta tesi doctoral s'analitza l'estabilitat hidràulica de mantells bicapa de roca, a partir d'assajos a escala reduïda realitzats amb pendent de fons m = 1/50. En base als resultats obtinguts dels assajos, es proposa una relació potencial per al disseny de mantells de roca en condicions d'onatge limitat per fons vàlida per a talussos amb cot¿ = 1.5, nombres d'estabilitat 0.98¿Hm0/(¿Dn50) ¿2.5, i profunditats relatives a peu de dic de 3.75¿hs/(¿Dn50)¿7.50. Quan mantell principal està format per elements de formigó , és habitual construir una berma de peu que proporciona suport als elements del mantell i, si escau, col¿labora en la protecció de la zona inferior del dic contra la soscavació. Aquesta berma sol construir amb roca i el seu pes està condicionat al dels elements del mantell en el cas de no haver trencament per fons. El pes dels elements de la berma de peu sol ser un ordre de magnitud inferior al pes de les unitats del mantell; però, si el pendent de fons és fort ( p.e. m = 1 /10) i les aigües someres aquesta regla no es compleix ja que algunes onades trenquen sobre el fons impactant directament sobre la berma de peu. En aquests casos, el pes de la roca de la berma pot sobrepassar el de les unitats del mantell, i el seu correcte disseny és crucial per garantir l'estabilitat del dic. A més d'estudiar l'estabilitat del mantell principal de dics de roca, la present tesi doctoral analitza també l'estabilitat hidràulica de bermes de roca ubicades en fons amb pendents m = 1/10 i aigües someres (0.5<hs/Dn50<5.01), utilitzant assajos a escala reduïda realitzats amb mantells de doble capa de cubs i bermes de roca amb diferents dimensions. En primer lloc, es proposa una nova equació per al disseny de bermes de roca estàndard (Bt = 3 Dn50 i tt = 2 Dn50), tant emergides com submergides, a partir de tres paràmetres: (1) alçada d'ona significant en aigües profundes, Hs0, (2) longitud d'ona en aigües profundes, L0p, i (3) profunditat a peu de dic, hs. Posteriorment, s'analitza la influència de l'amplada de la berma (Bt) en la seua estabilitat hidràulica, introduint dos nous conceptes per caracteritzar bermes de peu amples (Bt > 3 Dn50): (1) berma nominal o zona de la berma de peu sobre la qual recolza el mantell principal, i (2) berma de sacrifici o zona de la berma de peu que protegeix la berma nominal. A partir del dany de la berma de peu nominal, es proposa un nou mètode per reduir el tamany de roca (Dn50) incrementant l'amplada de la berma (Bt) quan no es disposi de la mida requerit en pedrera. Finalment, s'examina el dany del mantell de cubs i s'analitza la influència del mètode de col¿locació sobre el mateix , a partir d'assajos realitzats amb mantells bicapa de cubs amb col¿locació aleatòria i uniforme. / Herrera Gamboa, MP. (2017). Mound Breakwater Design in Depth-Limited Breaking Wave Conditions [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/82553

Stridsvagnsminan har varit ett vapen sedan 1916 och därefter har minan tillfört ytterligare en dimension till striden. Minorna har utvecklats under åren och blivit mer avancerade och fler system har möjlighet att placera ut minor. Understödsbehov och framtida bekämpningskoncept, en rapport från Artilleriets stridsskola, visade att avståndslagda minor är ett vapensystem som kan användas i striden för att bekämpa fordon. Försvarsmakten planerar att införskaffa ett system som har kapacitet till avståndslagd minering. Syftet med studien var att beskriva hur användningen av fordonsåverkande avståndslagda minor kan påverkas då de används i strid i olika svenska terrängtyper. Fem officerare från olika delar av Sverige intervjuades där de fick beskriva hur avståndslaga minor kunde användas i strid. Därefter analyserades svaren utifrån två scenarion, Skåne respektive Norrland, som representerar öppen terräng respektive betäckt terräng i syfte att se hur avståndslagda minors användning påverkar teorin om kombinerade vapen med en mekaniserad skyttebataljon. Analysen av de två scenariona visade att det blev svårare att uppnå kombinerade vapen i öppen terräng jämfört med betäckt terräng på grund av god framkomlighet och brist på kanaliserad terräng. Vilket skulle innebära att fler avståndslagda minorna skulle behövas för att påverka en motståndare i öppen terräng.

O presente trabalho propõe um modelo para avaliar a confiabilidade estrutural do cabo umbilical, levando em consideração os mecanismos de falha por escoamento e por fadiga mecânica. Esta análise é focada na avaliação estrutural das armaduras metálicas, dado que estes elementos suportam quase toda a carga à tração e limitam as deformações axiais da estrutura sem prejudicar significativamente a flexibilidade; desconsidera-se, portanto, o efeito estrutural do núcleo electro-óptico e das camadas polimérica interna e externa. Para esta finalidade são consideradas as tensões originadas pelos carregamentos das ondas do mar atuantes no cabo umbilical durante sua vida em serviço (plataforma semi-submersível GVA 4500 que opera na Bacia de Campos numa lâmina d água de 1000 m), assim como a geometria e as propriedades mecânicas das armaduras de tração utilizadas nos umbilicais dessas plataformas. Através da formulação de um modelo do cabo umbilical feito pelo Método dos Elementos Finitos determinou-se o histórico de tensões atuantes na estrutura, foram estimadas as funções de densidade de probabilidade da tensão estática e da tensão alternada corrigida para curto e longo prazo, as quais caracterizam o carregamento atuante provocado pelas ondas do mar. A caracterização do material é alcançada através de análise química e ensaios de tração. Finalmente, a metodologia proposta, que considera os mecanismos de falha por escoamento e por fadiga mecânica é implementada na prática. / A model to evaluate the structural reliability of the umbilical cable, taking into accounts the failure mechanism for yield strength and mechanical fatigue is proposed in this work. This analysis is focused on the structural evaluation of the metallic armors, given that these elements almost support the whole tensile load and they limit the axial deformations of the structure without harming the flexibility significantly, therefore, the structural effect of the electro-optical nucleus and the internal and external polymeric layers are not considered. For this purpose, the tensions originated by the loading of the waves of the active sea in the umbilical during its service life are considered (semi-submergible platform GVA 4500 that operates in Bacia de Campos into 1000 meters water depth), as well as the geometry and the mechanical properties of the tensile armors used in the umbilical of this platform. Through the formulation of a model for the umbilical cable, developed by the Finite Elements Method, the sequence of active tensions in the structure was determined and then the functions of density of probability of the static tension and of the alternate tension corrected for short and long period were estimated, which characterize the active loading caused by the waves of the sea. The characterization of the material is achieved through chemical analysis and tensile test. Finally, the proposed methodology, which considers the failure mechanisms by yields and mechanical fatigue is implemented in practice.

O presente trabalho propõe um modelo para avaliar a confiabilidade estrutural do cabo umbilical, levando em consideração os mecanismos de falha por escoamento e por fadiga mecânica. Esta análise é focada na avaliação estrutural das armaduras metálicas, dado que estes elementos suportam quase toda a carga à tração e limitam as deformações axiais da estrutura sem prejudicar significativamente a flexibilidade; desconsidera-se, portanto, o efeito estrutural do núcleo electro-óptico e das camadas polimérica interna e externa. Para esta finalidade são consideradas as tensões originadas pelos carregamentos das ondas do mar atuantes no cabo umbilical durante sua vida em serviço (plataforma semi-submersível GVA 4500 que opera na Bacia de Campos numa lâmina d água de 1000 m), assim como a geometria e as propriedades mecânicas das armaduras de tração utilizadas nos umbilicais dessas plataformas. Através da formulação de um modelo do cabo umbilical feito pelo Método dos Elementos Finitos determinou-se o histórico de tensões atuantes na estrutura, foram estimadas as funções de densidade de probabilidade da tensão estática e da tensão alternada corrigida para curto e longo prazo, as quais caracterizam o carregamento atuante provocado pelas ondas do mar. A caracterização do material é alcançada através de análise química e ensaios de tração. Finalmente, a metodologia proposta, que considera os mecanismos de falha por escoamento e por fadiga mecânica é implementada na prática. / A model to evaluate the structural reliability of the umbilical cable, taking into accounts the failure mechanism for yield strength and mechanical fatigue is proposed in this work. This analysis is focused on the structural evaluation of the metallic armors, given that these elements almost support the whole tensile load and they limit the axial deformations of the structure without harming the flexibility significantly, therefore, the structural effect of the electro-optical nucleus and the internal and external polymeric layers are not considered. For this purpose, the tensions originated by the loading of the waves of the active sea in the umbilical during its service life are considered (semi-submergible platform GVA 4500 that operates in Bacia de Campos into 1000 meters water depth), as well as the geometry and the mechanical properties of the tensile armors used in the umbilical of this platform. Through the formulation of a model for the umbilical cable, developed by the Finite Elements Method, the sequence of active tensions in the structure was determined and then the functions of density of probability of the static tension and of the alternate tension corrected for short and long period were estimated, which characterize the active loading caused by the waves of the sea. The characterization of the material is achieved through chemical analysis and tensile test. Finally, the proposed methodology, which considers the failure mechanisms by yields and mechanical fatigue is implemented in practice.

Achieving light weight armor design has become an important engineering challenge in the last three decades. As weapons becoming highly sophisticated, so does the ammunition, potential targets have to be well protected against such threats. In order to provide mobility, light and effective armor protection materials should be used. In this thesis, numerical simulation of the silicon carbide armor backed by KevlarTM composite and orthogonally impacted by 7.62mm armor piercing (AP) projectile at an initial velocity of 850 m/s is analyzed by using AUTODYN hydrocode. As a first step, ceramic material behavior under impact conditions is validated numerically by comparing the numerical simulation result with the test result which is obtained from the literature. Then, different numerical simulations are performed by changing the backing material thickness, i.e. 2, 4, 6 and 8mm, while the thickness of the ceramic is held constant, i.e. 8mm. At the end of the simulations, optimum ceramic/composite thickness ratio is sought. The results of the simulations showed that for the backing thickness values of 4, 6 and 8mm, the projectile could not perforate the armor system. On the contrary, the projectile could penetrate and perforate the armor system for the backing thickness value of 2mm and it has still some residual velocity. From these results, it is inferred that the optimum ceramic/composite thickness ratio is equal to about 2 for the silicon carbide and kevlar configuration.

Coastal defense structures have primary importance from obtainabilty of resources and benefits served by the coastal regions point of view. However, the construction of coastal defense structures demand a high amount of investment. Therefore, in order to reduce the risk of collapse of these structures, model studies should be carried during the design process. In this study, model investigations were carried out on Eastern Black Sea Highway Project regarding the serviceability and damage thus stability parameters. 5 different models were constructed as berm type rubble-mound breakwaters using Van Der Meer&rsquo / s approach and berm design guidelines, with a scale of 1/31.08 and they were tested both for breaking and non-breaking waves. The experiments took place in the Coastal and Harbor Engineering Laboratory of the Middle East Technical University, Civil Engineering Department. The models were constructed and tested with different berm widths and armor stone sizes forming the back armor layer in order to examine the effect of these design parameters on the stability and serviceability of the coastal defense structure to obtain the optimum alternative cross-section. Cumulative damage was minimum for the cross-section constructed with berm width 15 m assigning the width of the prototype. Water spray and run-up values were also not significant. The test results were confirming with Van Der Meer design approach.