An Experimental and Numerical Study of Ballistic Impacts on a Turbine Casing Material at Varying Temperatures

An experimental and numerical study of ballistic impacts on steel plates at various temperatures (700ºC, 400ºC and room temperature) has been carried out. The motivation for this work is the blade‐off event that may occur inside a jet engine turbine. However, as a first attempt to understand this complex loading process, a somewhat simpler approach is carried out in the present work. The material used in this study is the FV535 martensitic stainless steel, which is one of the most commonly used materials for turbine casings. Based on material test data, a Modified Johnson‐Cook (MJC) model was calibrated for numerical simulations using the LS‐DYNA explicit finite element code (see Figure 1). To check the mesh size sensitivity, 2D axisymmetric finite element models with three different mesh sizes and configurations were used for the various temperatures. Two fixed meshes with 64 and 128 elements over the 2mm thick plate and one mesh with 32 elements over the thickness with adaptive remeshing were used in the simulations. The formation of adiabatic shear bands in the perforation process has been found critical in order to achieve good results. Adiabatic shear bands are formed by the temperature rise due to the accumulation of plastic strain during impact (see Figure 2). The influence of the thermal softening in the plastic model has hence been analyzed for the room temperature impact tests, where the temperature gradient is highest

Biomimetismo entre los endemismos arquitectónicos y taxones en Cantabria

Es notoria la importancia de la naturaleza en la evolución de la arquitectura. Hasta la gran eclosión de la industria manufacturera y la mejora en las infraestructuras de comunicación, se podría decir que ambas corrían paralelas, para a partir de ahí dejar “congelada” la sabiduría popular y dar un salto a la globalidad, generando una situación de libertad arquitectónica prácticamente total, que independiza la construcción de su ubicación. "El biomimetismo es esencialmente un campo de investigación interdisciplinar, una serie de colaboraciones entre botánicos, físicos, matemáticos, ingenieros y zoólogos; donde la rígida división entre disciplinas «puras» cede lugar a un área de investigación que apunta a generar tecnología inteligente (smarttechnologies), utilizando materiales o procesos que sean de alguna manera sensibles al medio ambiente." (M. Weinstock, 1998). “La morfología de las plantas en los diferentes climas parece tener cierta analogía con la edificación, ya que algunas de las tensiones que inciden en su forma (tales como las variaciones de temperatura) corresponden de manera similar a las necesidades humanas.” (V. Olgyay 1963). En el presente trabajo se han estudiado las especies endémicas que nos rodean, para poder leer a través de ellas millones de años de supervivencia en este entorno, con el fin de mimetizar sus respuestas. También se han estudiado diferentes tipologías de arquitectura vernácula y su simulación energética, con el propósito de evaluar la demanda energética optima exigible. A partir de una ubicación específica, la orientación, compacidad, perforación y las características de la envolvente son los elementos que más influyen en la demanda energética de una edificación. Tanto la forma como los materiales pueden ser mimetizados con la naturaleza. En esta Tesis se han cuantificado los parámetros de diseño formales tomando como referencia las especies vegetales o la arquitectura vernácula, sin perder de vista los objetivos buscados por normativas o institutos en la reducción del consumo energético vinculado a la calefacción y ventilación. ABSTRACT The importance of the nature in the evolution of the architecture is well-known. Until the great burst of the manufacturing industry and the improvement in communication infrastructures, it would be possible to be said that both ran parallel, stops there from leaving “frozen” the popular wisdom and jump to the globalization, creating a situation almost complete architectural freedom, that it frees the construction of its location. "Biomimicry is essentially an interdisciplinary field of research, a series of collaborations among botanists, physicists, mathematicians, engineers and zoologists; where the rigid division between "pure" disciplines gives way to an area of research that aims to generate intelligent technology (smarttechnologies), using materials and processes that are in some environmentally sensitive manner. "(M. Weinstock, 1998). “The morphology of the plants in different climates seems to have some analogy with the building, as some of the tensions that affect their form (such as the temperature variations) are similar to the human necessities.” (V. Olgyay 1963). In the present work, the endemic species that surround to us have been studied, to be able to read through them millions of years of survival in this environment, in order to mimic their answers. Also different types or popular architecture and their energy simulation have been studied, in order to evaluate the rate of energy optimum demand. Orientation, compactness, perforation and characteristics of the envelope are the elements that influence more in the energy demand of a building. The shape and materials can be mimic with nature. Each of them has been quantified in this work by reference plant species or popular architecture, without losing sight of the objectives sought by regulations or institutes about reduction in energy consumption.

Physically-sound simulation of low-velocity impact on fiber reinforced laminates

A high-fidelity virtual tool for the numerical simulation of low-velocity impact damage in unidirectional composite laminates is proposed. A continuum material model for the simulation of intraply damage phenomena is implemented in a numerical scheme as a user subroutine of the commercially available Abaqus finite element package. Delaminations are simulated using of cohesive surfaces. The use of structured meshes, aligned with fiber directions allows the physically-sound simulation of matrix cracks parallel to fiber directions, and their interaction with the development of delaminations. The implementation of element erosion criteria and the application of intraply and interlaminar friction allow for the simulation of fiber splits and their entanglement, which in turn results in permanent indentation in the impacted laminate. It is shown that this simulation strategy gives sound results for impact energies bellow and above the Barely Visible Impact Damage threshold, up to laminate perforation conditions