Fatigue strain fields comparison between Synchrotron X-Ray Diffraction and 3D Numerical computation in a bainitic steel.

Engineers prioritize resource preservation when designing lightweight materials, but fatigue can pose challenges. Although various experimental methods exist for studying fatigue cracks, some are only effective for transparent materials. For example, transmission photo-elasticity is limited in application, and post-failure metallography and micro-indentation cannot be adopted during mechanical testing. However, Synchrotron X-ray diffraction experiments can obtain valuable data from the bulk of metallic materials. A study was done on a 12mm thick Compact Tension bainitic steel sample (used in civil engineering and Wind offshore industry). A fatigue test was conducted by applying 51,000 loading cycles at a frequency of 10 Hz, ΔP=14.9KN (0.5kN to 15.4kN), followed by a 24.5 kN load. We analyzed the strain fields along the crack growth direction (εxx) and loading direction (εyy). Both experimental and Finite Element Methods data showed promising results with similar strain field shapes and values, showing as well consistency with mode I loading.Authors are grateful for the beam time granted by the ESRF (MA1483). Authors would also like to acknowledge the financial support of Programa Operativo FEDER (Junta de Andalucia, Spain) through grant reference UMA18-FEDERJA-250. This work was also supported by the Henry Royce Institute for Advanced Materials, funded through EPSRC grants EP/R00661X/1, EP/S019367/1, EP/P025021/1, and EP/P025498/1 and the European Social Found, through the Youth Employment Initiative, grant reference UMAJI84. The authors are especially thankful to Manuel Carrera for his help in the early stages of this study. We would also acknowledge funding for open access charge: Universidad de Malaga / CBUA. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Analysis of fatigue strain fields with synchrotron x-ray diffraction and 3d numerical computation.

When designing lightweight materials, engineers prioritise resource preservation but often encounter issues with fatigue. Various experimental methods exist to study fatigue cracks; nevertheless, transmission photo-elasticity is only effective for transparent materials, and post-failure metallography and micro-inden-tation cannot obtain fatigue test data. Synchrotron X-Ray Diffraction (S-XRD) experiments allow us to get data from the bulk of metallic materials. It was conducted a study on a CT bainitic steel sample that was 3.3mm thick. During the fatigue test, we applied 30,000 loading cycles at a frequency of 20 Hz, followed by an 8,800 N load. We analysed strain fields along the crack growth direction εxx and loading direction εyy. Both experimental and Finite Element Methods (FEM) data showed promising results, as observed in the similar strain field shapes with similar maximum values. We observed symmetry along the X-axis, consistent with mode I loading.UMA18-FEDERJA-250 UMAJI84 Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Fatigue crack growth behaviour of selective laser-melted 18NI300 manufactured at 0º, 45º and 90º to perpendicular crack growth plane

The use of selective laser melting (SLM) as a method of additive manufacturing (AM) of valuable objects has a promising future. Maraging steel is a widely used material due to its excellent qualities in AM, so it is essential to know the fatigue mechanisms existing in this material manufactured at different angles. The current state of research in fracture mechanics applied to additive manufacturing has been analyzed to determine the importance of mechanical properties in this process. The CT samples were laser fabricated in three orientations with respect to the intended crack plane; the angles used are 0-, 45- and 90-degrees respect from the displacement. Fatigue tests show a longer service life with the 90-degree specimens than with the 0-degree specimens, with a reduction up to 20% for the 0-degree tests. On the 45-degree specimens, a 40% reduction is observed compared to the 90-degree specimens, and there is no apparent reason. A fracture surface analysis has shown different textures on the 45-degree specimens, with rougher surfaces in certain tests due to a rougher application of load. This also results in sharper ridges signifying rapid cracking due to shorter periods of higher forces. In addition, it is necessary to continue the study to obtain the da/dN curves, as well, the reasons for these difference in surface areas.UMA18-FEDERJA-250 y POCI-01-0247-FEDER-042536. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A Framework for Strategic Intelligence Systems Applied to Education Management: A Pilot Study in the Community of Madrid

The management of educational policies is a complex issue. There are complexities related to the country's organizational system (competencies delegated by different areas in some cases), and to the limited resources in the educational system. In addition, there are many variables that need to be managed: ICT resources, special educational needs, human resources available, the socioeconomic characteristics of each district, etc. These types of issues are similar to those dealt with by strategic intelligence management. In this field, commonly included within innovation management, methodological frameworks are established that enable collection and consolidation of data from various sources and their subsequent exploitation to enhance decision-making based on previously identified needs. This article presents the details of a pilot plan aimed at implementing a framework for strategic intelligence management in the educational management system of the Community of Madrid (Spain). These intelligence systems are difficult to deploy in educational organizations that have highly fragmented management as in the case described in our pilot plan, although their implementation leads to more correct and agile decision-makings. This paper describes the steps carried out to define the new management platform requirements, its technical implementation issues, and the validation results that demonstrate its functional validity and acceptance by end-users participating in the described pilot project

Método para la comparación y caracterización del ruido de paso en trenes de alta velocidad

El ferrocarril está llamado a ser uno de los modos de transporte del futuro tanto para mercancías como para viajeros. Esto conduce a la necesidad de reducir los efectos negativos que la explotación ferroviaria produce, y entre ellos los más relevantes son el ruido y las vibraciones, que causan molestias a usuarios y habitantes cercanos y perturbaciones en infraestructuras propias de la red o cercanas a la misma. En el trabajo de investigación que aquí se resume, se ha realizado un estudio teórico exhaustivo de los fenómenos de emisión de ruido ferroviario analizando sus causas y parámetros de influencia. A partir de este estudio, se ha elaborado una metodología completa y sencilla para la caracterización del ruido de paso que cubre todas las fases necesarias, desde la adquisición de datos de ruido, hasta la obtención de resultados numéricos y de forma gráfica a través de una herramienta software desarrollada a tal efecto. De las distintas metodologías de caracterización se escogió, por ser la más representativa para el estudio, la caracterización del ruido de paso de vehículos (a velocidad constante). La herramienta informática, la metodología en sí y sus resultados han sido comprobados y ratificados con ensayos reales en las instalaciones de Alta Velocidad de la red española, registrándose el paso de diferentes composiciones. Además se puede afirmar que cumplen con las especificaciones y restricciones establecidas por la normativa vigente en España y Europa. Este trabajo ha sido desarrollado en el Centro de Investigación en Tecnologías Ferroviarias (CITEF), centro ligado a la Escuela Técnica Superior de Ingenieros Industriales de la Universidad Politécnica de Madrid

Adverse aerodynamics effects of a high speed train under the influence of cross winds, analysis and optimization of wind fence

The research work that here is summarized, it is classed on the area of dynamics and measures of railway safety, specifically in the study of the influence of the cross wind on the high-speed trains as well as the study of new mitigation measures like wind breaking structures or wind fences, with optimized shapes. The work has been developed in the Research Center in Rail Technology (CITEF), and supported by the Universidad Politécnica de Madrid, Spain

Análisis de contenido de los programas resumen de baloncesto en Movistar+

El baloncesto es el segundo deporte más practicado en España pero esta condición no se plasma en los medios de comunicación ya que el fútbol monopoliza la información. En este trabajo Final de Grado se pretende analizar la importancia que desde la plataforma que posee los derechos de emisión en España se le da al baloncesto. También se investigará si Movistar+ se apoya en un formato de infoentretenimiento para la realización de sus programas, si se ajusta a las características y se analizarán sus contenidos. La investigación ha demostrado que Movistar+ ha encontrado una forma de presentar el producto de una manera muy cercana al infoentretenimiento y de una forma similar en todos sus espacios

Predicted photoreflectance signatures on QD selective contacts for hot carrier solar cells

The CO2 emission of our present energy transformation processes, based mainly on burning fossil fuels, is possibly the main cause of global climatic change. The photovoltaic conversion of solar energy is a clean way of producing which for sustainability should (and most probably will) become a major source of electricity. The sun is a huge resource but relatively diluted and it is reasonable to expect that only high efficiency extraction can be cost effective for mass exploitation. New concepts are neccessary such as hot carrier solar cells

Analysis of the stress state at the double-step joint in heavy timber structures

The double-step joint is among the most frequently used layouts, within carpentry joints, for transmitting higher forces that would allow a single notch. They are especially effective in heavy timber structures. Nowadays, computer-aided manufacturing is being used more often, demanding further progress in its understanding. The conventional design of these joints is conducted by using simplifying assumptions, in particular regarding the shear stress distribution. This is overcome by the use of strength reduction coefficient, which is currently under study. Numerical simulation and experimental tests were carried out with heavy timber crosssections for rafter to tie-beam truss joint. They were manufactured in glue-laminated timber owing to the large cross-sections tested. Experimental load-strain and load-displacement diagrams were compared with numerical results. This allowed observing the great shear stress concentration produced in the failure by shear crack, which suggests the application of conservative shear strength reduction coefficients.Análisis del estado tensional de la unión por embarbillado doble en estructuras pesadas de madera. Entre las uniones carpinteras, el embarbillado doble es una de las más utilizadas para transmitir cargas superiores a las que permitiría una única entalladura, especialmente interesante para estructuras pesadas. Hoy en día, la fabricación asistida por ordenador ha estimulado su uso, demandando profundizar en su estudio. El diseño convencional de estas uniones se realiza asumiendo supuestos simplificadores, en particular respecto a la distribución de las tensiones tangenciales en el cogote. Derivando en el empleo de factores de penalización de la resistencia, los cuales continúan actualmente en estudio. Se realizaron ensayos con escuadrías propias de cerchas pesadas en configuración par-tirante, empleándose para ello madera laminada. Los gráficos experimentales de carga-deformación y carga-desplazamiento se compararon con la modelización numérica de la unión. Esto permitió apreciar la importante concentración de tensiones tangenciales que se produce en el fallo por rasante, lo que aconseja la aplicación de factores reductores de resistencia a cortante conservadores.The Spanish Government supported this work, research project: AGL2012-39368-C03-01, National R+D+I Plan of the Ministry of Science and InnovationS

Oxigenoterapia y cuidados paliativos en pacientes con insuficiencia cardiaca. Respuesta

Letter to the Edito