Ángel García-Beltrán

Evaluation and implementation of social responsibility

This work sets out an innovative methodology that aims to facilitate the implementation and continuous improvement of social responsibility. It is a methodology that takes account of strategic-economic, social and environmental questions and allows measuring the impact of each of these aspects on the stakeholders and on each of the value areas. It can be extrapolated to all kinds of organisations regardless of their size and sector and admits scalable models. A marked feature that sets it aside from other methodologies is that it eliminates subjectivity from the qualitative aspects and introduces an algorithm to quantify them.

A new approach for the solution of the neighborhood problem in meshfree methods

This article introduces a new point of view in the description and solution of neighborhood problems and, more specifically, to those arising in meshfree or simulations in computational mechanics. In particular, we focus on the solution of neighborhood computations when the problem involves two distinct sets of points whose positions change, and whose proximity needs to be repeatedly assessed. With this type of problems in mind, we reformulate the neighborhood concepts and propose a solution—implemented in an open source library—that possesses a simple interface, is suitable for parallelization, has very mild restrictions on the point data, depends only on the standard C++ library, and has a small memory impact. The presented algorithm employs hash tables to achieve constant time in point searches, integer lattices to define a grid of background cells, and classifies the two independent point sets. As a result, and in addition to the favorable features previously indicated, the method is very fast as compared with the available implementations for similar problem.

Numerical-Experimental Study of the Consolidation Phenomenon in the Selective Laser Melting Process with a Thermo-Fluidic Coupled Model

One of the main limiting factors for a widespread industrial use of the Selective Laser Melting Process it its lack of productivity, which restricts the use of this technology just for high added-value components. Typically, the thickness of the metallic powder that is used lies on the scale of micrometers. The use of a layer up to one millimeter would be necessarily associated to a dramatic increase of productivity. Nevertheless, when the layer thickness increases, the complexity of consolidation phenomena makes the process difficult to be governed. The present work proposes a 3D finite element thermo-coupled model to study the evolution from the metallic powder to the final consolidated material, analyzing specifically the movements and loads of the melt pool, and defining the behavior of some critical thermophysical properties as a function of temperature and the phase of the material. This model uses advanced numerical tools such as the Arbitrary Lagrangean–Eulerian formulation and the Automatic Remeshing technique. A series of experiments have been carried out, using a high thickness powder layer, allowing for a deeper understanding of the consolidation phenomena and providing a reference to compare the results of the numerical calculations.

Computer-Aided Development of Thermo-Mechanical Laser Surface Treatments for the Fatigue Life Extension of Bio-Mechanical Components

Bio-mechanical components (i.e. spinal, knee and hip prostheses) are key elements definitely improving the quality of life of human beings. These components development has been traditionally subject to mechanical and functional designs based primarily on intuitive medical approaches, not always optimized from an engineering point of view, what in turn has been responsible for undesirable cases of mechanical failure implying the need for additional surgical interventions and its associate life risk for aged patients. Laser Shock Processing (LSP) uses the high peak power of short pulse lasers to generate an intense shock wave into the material finally leading to the generation of a compressive residual stresses field definitely protecting the component against crack initiation and propagation, thus improving its mechanical response and in-service fatigue life. Developments in the field of the predictive assessment of LSP are presented along with practical examples of the design-motivated improvements in prostheses achievable by LSP.

Characteristics of Miab welding process and joints

The paper presents the MIAB welding of thin walled tubes achieved with an original longitudinal magnetization system, designed to assure the magnetic flux concentration on the tube wall. Based on images resulting from process monitoring, the main stages of the process are presented, starting with arc initiation, to apparition of molten metal, upsetting and ending with the weld achievement. Infrared thermography was also used for temperature measurements and visualization of the process. Macro and microstructural analyses accompany the hardness tests made on correspondingly welded samples, demonstrating the process capability in producing sound joints when guided by the operational windows developed through this investigation.