Data fluidity in DARIAH -- pushing the agenda forward

This paper provides both an update concerning the setting up of the European DARIAH infrastructure and a series of strong action lines related to the development of a data centred strategy for the humanities in the coming years. In particular we tackle various aspect of data management: data hosting, the setting up of a DARIAH seal of approval, the establishment of a charter between cultural heritage institutions and scholars and finally a specific view on certification mechanisms for data

Independent associations between sedentary time, moderate-to-vigorous physical activity, cardiorespiratory fitness and cardio-metabolic health : a cross-sectional study

We aimed to study the independent associations of sedentary time (ST), moderate-to-vigorous physical activity (MVPA), and objectively measured cardiorespiratory fitness (CRF) with clustered cardio-metabolic risk and its individual components (waist circumference, fasting glucose, HDL-cholesterol, triglycerides and blood pressure). We also investigated whether any associations between MVPA or ST and clustered cardio-metabolic risk were mediated by CRF. MVPA, ST, CRF and individual cardio-metabolic components were measured in a population-based sample of 341 adults (age 53.8 +/- 8.9 years; 61% men) between 2012 and 2014. MVPA and ST were measured with the SenseWear pro 3 Armband and CRF was measured with a maximal exercise test. Multiple linear regression models and the product of coefficients method were used to examine independent associations and mediation effects, respectively. Results showed that low MVPA and low CRF were associated with a higher clustered cardio-metabolic risk (beta = -0.26 and beta = -0.43, both p<0.001, respectively). CRF explained 73% of the variance in the association between MVPA and clustered cardio-metabolic risk and attenuated this association to non-significance. After mutual adjustment for MVPA and ST, CRF was the most important risk factor for a higher clustered cardio-metabolic risk (beta = -0.39, p<0.001). In conclusion, because of the mediating role of CRF, lifestyle-interventions need to be feasible yet challenging enough to lead to increases in CRF to improve someone's cardio-metabolic health

On the Role of Interfacial Reactions, Dissolution and Secondary Precipitation During the Laser Additive Manufacturing of Metal Matrix Composites: A Review

Since current trends in the transportation, energy or mechanical industries impose increasingly demanding service conditions for metallic parts, metal matrix composites (MMCs) are the object of a growing interest. Powder-based laser additive manufacturing, which allows making parts with complex shapes, appears particularly adapted for the production of MMCs. This paper reviews the current state-of-the-art in the production of MMCs by additive processes, with the aim of assessing the potentials and difficulties offered by these techniques. Two main processing routes are envisaged, i.e. (1) the processing of ex situ composites in which the reinforcing phase as a powder—often of ceramic particles—is directly mixed with the powder of the matrix alloy, and both powders are simultaneously processed by the laser. (2) Alternatively, the reinforcing phase can be produced in situ by a chemical reaction during the fabrication of the composite. For both processing routes, a careful control is needed to overcome challenges brought, e.g. by the behaviour of the reinforcement particles in the laser beam, by changes in laser absorptivity or by the dissolution of the reinforcing particles in the molten metal, in order to produce MMCs with enhanced usage properties

An Introduction to the Additive Manufacturing of Metallic Materials - Two Case Studies on the Processing of Stainless Steel 316L and of Ti Alloy Ti-6Al-4V

This powerpoint presentation was used as teaching material in a seminar given as part of the course “Ingénierie des matériaux métalliques” at Université de Liège. It outlines important current issues in the developments of additive technologies for the processing of metallic materials by discussing two case studies from researches carried out by the Metallic Materials Science Unit (ULg). In particular, two different metallic alloys, i.e. stainless steel 316L and Ti-6Al-4V, have been processed by laser beam melting under similar conditions, and their microstructures and mechanical behaviours have been compared in details. Under the investigated conditions, Ti-6Al-4V exhibits a more complex behaviour than stainless steel 316L with respect to the occurrence of microstructural and mechanical anisotropy. Moreover, Ti-6Al-4V appears more sensitive to the build-up of internal stresses when compared with stainless steel 316L, whereas stainless steel 316L appears more prone to the formation of “lack of melting” defects. This correlates nicely with the difference in thermal conductivity between the two materials. Thermal conductivity was also shown to increase strongly with increasing temperature

Laser Additive Manufacturing of Metal Matrix Composites

Current trends in the mechanics and energy industries impose increasing demands on metallic materials, combining elevated service temperatures and severe mechanical solicitations. Metal matrix composite coatings with ceramic reinforcements are good candidates in view of fulfilling the requirements for an improved mechanical durability, and for other complex functions (e.g. self-lubrication, biocompatibility...). First of all, this paper provides an introduction to metal matrix composites with a particular attention for the process known as laser cladding that appears as a promising technology for making composite coatings. In this process, a (mixture of) metallic powder(s) is projected onto a substrate through a nozzle and simultaneously melted by a laser beam. Laser cladding is characterised by ultra-fast solidification and cooling rates, thus giving rise to ultra-fine microstructures and potentially enhanced mechanical properties. The paper thus focuses on the relationships between the thermal history during the production of a composite coating, and the resulting microstructure and properties, with special attention to the dissolution of ceramic particles (e.g. carbides) and to interfacial reactions taking place between the particles and the metallic matrix

Thermal Treatments of AlSi10Mg Processed by Laser Beam Melting

peer reviewedRecent studies have shown that AlSi10Mg processed by Laser Beam Melting (LBM) exhibits a much finer microstructure when compared to its cast counterpart as a consequence of the much faster cooling rates imposed in the LBM process. Such microstructural refinement causes a significant increase in strength and hardness, to such an extent that as-fabricated LBM AlSi10Mg was reported to present hardness value of 127 ± 3 Hv0.5, similar to the hardness of high pressure die cast AlSi10Mg in the aged condition (i.e. 130-133 Hv). Yet, little attention has been given so far to the influence of thermal treatments on the microstructure and mechanical behavior of LBM AlSi10Mg. The present work hence aims to investigate the effect of two different types of heat treatments – i.e. (i) stress relief and (ii) solutionizing and ageing − on the microstructure, hardness and tensile properties of LBM AlSi10Mg

Prediction of Phase-transformations of Ti6Al4V additively manufactured during Directed Energy Deposition

editorial reviewedDirected Energy Deposition (DED) has been highly used to fabricate and repair components made from different metallic alloys. The characteristics of this process enhances high cooling and heating rates, which results in an out-of-equilibrium microstructures of the build parts. Ti6Al4V additively manufactured alloy is widely used in a variety of applications such as aerospace, automotive, marine equipment and biomechanical applications. However, the improvement of its mechanical properties is still a challenge because they are influenced by the process conditions. The Mechanics of Solid and Materials (MSM) and Metallic Solid Materials (MMS) of ULiège have been focused to correlate DED process parameters and the obtained microstructures. The approach has been based on a strong combination between experimental investigations and numerical modelling [1, 2, 3]. First investigations on this topic consisted in the implementation of a numerical model to predict phase transformations of Ti6Al4V [1]. This approach is based on discretization of the thermal histories (heating and cooling) which have been obtained by Finite Element simulations [3] to capture temperature oscillations in the clad parts during Manufacturing. An advanced approach, consisting in the segmentation of the temperature history in different Time-phase – Temperature – Blocks (TTB) [2], allows the correlation between the thermal histories and the final microstructure. In this context, in a first step, we proceed by summarizing the previous results. Then, a new achievement consisting in modelling a “meso-clad” of Ti6Al4V with mutli-validations (multiple thermocouples and microscopic measurements) is presented. Finally, we present our perspectives by exploiting promising tools in particular machine learning.9. Industry, innovation and infrastructur

About the use of Phase Field and FE to predict micostructures, Application on AlSi10Mg samples produced by Additive Manufacturing

Background & motivations Finite Element (FE) model in Additive Manufacturing (AM) AlSi10Mg Microstructure evolution FE Model of L-PBF (SLM) AlSi10Mg Phase-field model of microstructure evolution: Model description Model parameters Simulated calorimetric curve Conclusion

Adaptive time stepping approach for Phase-Field modeling of phase separation and precipitates coarsening in additive manufacturing alloys

In the present work, the capacity of phase field method to highlight microstructural changes during the spinodal decomposition of a given binary alloy basing on the Cahn-Hilliard equation is presented. Then, growth and coarsening of precipitates are studied using the KKS (Kim-Kim-Suzuki) model, which includes Cahn-Hilliard and Allen-Cahn equations. The implementation of time stepping algorithms to resolve Phase-Field equations is illustrated. Within Fourier space, using semi-implicit spectral method, it has been demonstrated that it allows faster computing than schemes based on finite difference method. First, spinodal decomposition of a given binary alloy under isothermal loading is implemented and three time stepping approaches are applied: constant time stepping, non- iterative and an iterative method. While the non-iterative method is faster than the constant time stepping scheme, the iterative one, although relatively more CPU consuming, can guarantee the convergence of the computing. These methods are combined in an innovative approach tested on 1D, 2D and 3D grids. The effectiveness of the adopted adaptive time-stepping algorithm allows resolving equations in reasonable CPU time. It predicts different physical phenomena, such as phase separation and growth and coarsening of precipitates induced by important interfacial energies