Nuevas metodologías docentes para la enseñanza de estructuras aeronáuticas.

La asignatura “Estructuras Aeronáuticas” está orientada a completar los conocimientos del análisis de estructuras del futuro ingeniero aeronáutico. La organización y programación de la asignatura está pensada para transmitir los conocimientos necesarios para el cálculo de estructuras laminares mediante métodos clásicos y modernos, como el basado en el Análisis con Elementos Finitos (AEF), de manera que el alumno posea una perspectiva amplia de la problemática asociada al diseño de estructuras laminares como las que integran una aeronave. Ello se lleva a cabo mediante clases teóricas, clases de problemas, clases prácticas de estructuras por ordenador y trabajos prácticos. En este trabajo se presentan nuevas metodologías docentes implementadas e introducidas en el esquema docente de dicha asignatura con objeto de satisfacer las líneas prioritarias del Plan Propio de la Universidad de Sevilla sobre metodologías docentes. De esta forma se llevan a cabo diferentes frentes de actuación: estudio y experimentación de nuevas metodologías didácticas como la enseñanza virtual, usando plataformas virtuales tipo WebCT, la elaboración de clases por transparencias PowerPoint y animaciones a partir de material específico, y la promoción del trabajo en equipo mediante la realización de un proyecto en grupo de AEF de un ala de una aeronave de recreo. El modelado mediante elementos finitos se realizará empleando el software comercial NASTRAN ® y PATRAN ® , de extensa aplicación en el sector aeronáutico

Influence of micromechanics in composite panels buckling loads

Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.In-plane compression loads may cause buckling of fiber-reinforced composite panels. An accurate knowledge of these critical buckling loads is essential for structural design. In all cases of buckling of panels, critical loads increases with the increase in the thickness of the panel, however, more economical solutions can be obtained by keeping the thickness of the plate as small as possible and increasing the stability by considering micromechanical aspect such as: fiber orientation relative to axial direction, fiber aspect ratio or fiber volume fraction. This paper presents some parametric studies to study the influence of micromechanics in the critical buckling load of fiber-reinforced plates and curved panels

3D thermoelastic solids under non‐linear interface thermal and orthotropic frictional contact conditions

[EN] This article presents a robust and efficient methodology to study three-dimensional thermoelastic contact problems under orthotropic friction conditions, including the effects of non-linear thermal contact conductance and convective boundary conditions at the interstitial contact zone. The proposed methodology considers the boundary element method to compute the thermomechanical influence coefficients and an augmented Lagrangian formulation to ensure the fulfillment of all these thermomechanical contact conditions. The resulting non-linear equation set have been solved by an efficient proposed iterative Uzawa scheme. The proposed formulation has been validated by comparison with some available results in the literature and later on, it is considered to study how the thermoelastic contact variables are affected by both: the non-linear interface thermal and the orthotropic friction conditions in different engineering problems such as a brake disc-pad contact system.SIPublicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL

3D thermoelastic solids under non‐linear interface thermal and orthotropic frictional contact conditions

[EN] This article presents a robust and efficient methodology to study three-dimensional thermoelastic contact problems under orthotropic friction conditions, including the effects of non-linear thermal contact conductance and convective boundary conditions at the interstitial contact zone. The proposed methodology considers the boundary element method to compute the thermomechanical influence coefficients and an augmented Lagrangian formulation to ensure the fulfillment of all these thermomechanical contact conditions. The resulting non-linear equation set have been solved by an efficient proposed iterative Uzawa scheme. The proposed formulation has been validated by comparison with some available results in the literature and later on, it is considered to study how the thermoelastic contact variables are affected by both: the non-linear interface thermal and the orthotropic friction conditions in different engineering problems such as a brake disc-pad contact system.S

Innovación y mejora docente en el ámbito de la enseñanza de estructuras metálicas.

La asignatura “Estructuras Metálicas” está orientada a completar los conocimientos del análisis de estructuras del futuro ingeniero industrial con su aplicación práctica al diseño de estructuras metálicas. La organización y programación de la asignatura está pensada para transmitir los conocimientos necesarios para el cálculo de elementos estructurales simples, de manera que el alumno posea una perspectiva amplia de la problemática asociada al diseño de estructuras metálicas complejas. Ello se lleva a cabo mediante clases teóricas, clases de problemas, clases prácticas de estructuras por ordenador, prácticas de laboratorio, y trabajos prácticos. Este trabajo presenta nuevas metodologías docentes, de acuerdo con las líneas prioritarias del Plan Propio de la Universidad de Sevilla, para mejorar los diferentes frentes de docencia que la asignatura posee. Para ello se profundiza en el estudio y experimentación de nuevas metodologías didácticas como la enseñanza virtual, usando plataformas virtuales tipo WebCT, la elaboración de clases por transparencias PowerPoint y animaciones numéricas realizadas mediante elementos finitos, todo ello basadas en la normativa vigente actual y bibliografía referente actualizada. Además se fomenta el trabajo en equipo mediante la realización de prácticas de campo y un proyecto en grupo, y se desarrollan nuevas prácticas de laboratorio y actividades de manera que el alumno contemple la visión práctica de los conocimientos adquiridos

Crack-induced electrical resistivity changes in cracked CNT-reinforced composites.

Política de acceso abierto tomada de: https://v2.sherpa.ac.uk/id/publication/12462Carbon nanotube (CNT)-reinforced composites exhibit a piezoresistive behavior that permits their use as sensors in novel structural health monitoring (SHM) applications, by measuring the electrical resistivity change of the CNT modified laminate. However, the presence of cracks in such composite materials may not only compromise their struc- tural integrity, but may as well alter their capability to act as reliable piezoresistive sensors. In this paper, we conduct a numerical study aimed at quantifying how the presence of cracks in reinforced polymer composites does influence their electrical conductivity and, consequently, their sensor performance. To this end, the electromechanical constitu- tive properties of the composite are determined by a mixed micromechanics approach that allows characterizing both the elastic properties and the strain-induced alterations in the overall electrical conductivity of the CNT-reinforced composite. The strain response of the cracked composite domain is accurately determined by means of a dual Boun- dary Element (BE) approach. Electrical conductivity in the cracked composite follows from its computed strain state at each point in the domain. Subsequently, the resulting non-homogeneous electrical conductivity problem is sol- ved using a finite differences scheme that also accounts for semipermeable crack-face electrical boundary conditions. Several parametric studies are conducted to illustrate the influence of various crack geometries in the piezoresistive behavior of CNT-reinforced composites at varying CNTs concentrations.Ministerio de Economía y Competitividad de España y European Regional Development Fund, proyectos RTI2018-094945-B-C21 y DPI2017-89162-

Lead-free piezocomposites with CNT-modified matrices: Accounting for agglomerations and molecular defects.

Piezoelectric matrix-inclusion composites based on lead-free ceramics have attracted attention due to the possibility of manufacturing environmentally friendly devices using scalable emerging technologies such as 3D printing. However, lead-free materials lag lead-based piezo-composites in terms of performance, thus necessitating new design strategies to escalate piezoelectric response. Here, we build a modeling paradigm for improving the piezoelectric performance through improved matrices and optimal polycrystallinity in the piezoelectric inclusions. By incorporating carbon nanotubes in the matrix, we demonstrate 2-3 orders of improvement in the piezoelectric response, through simultaneous hardening of the matrix and improvement in its permittivity. By tuning the polycrystallinity of the piezoelectric inclusions, we show considerable improvements exceeding 50% in the piezo-response, compared to single crystal inclusions. We further analyze the influence of carbon nanotube agglomerations at supramolecular length scales, as well as vacancy defects in the nanotubes at the atomic level, on composite performance. Although nanomaterial agglomeration is conventionally considered undesirable, we show that, near nanotube percolation, clustering of nanotubes can lead to better matrix hardening and higher permittivities, leading to improvements exceeding 30% in the piezoelectric response compared to non-agglomerated architectures. We further demonstrate that although atomic vacancy defects in nanotubes effectively soften the matrix, this can be compensated by agglomeration of nanotubes at larger length-scales.Ministerio de Economía y Competitividad de España y European Regional Development Fund, proyectos DPI2014-53947-R y DPI2017-89162-R. Programa NSERC and CR