Defining quantumness via the Jordan product

We propose alternative definitions of classical states and quantumness witnesses by focusing on the algebra of observables of the system. A central role will be assumed by the anticommutator of the observables, namely the Jordan product. This approach turns out to be suitable for generalizations to infinite dimensional systems. We then show that the whole algebra of observables can be generated by three elements by repeated application of the Jordan product

Effect of in-mould inoculant composition on microstructure and fatigue behaviour of heavy section ductile iron castings

In this paper, the influence of the in-mould inoculant composition on microstructure and fatigue behaviour of heavy section ductile iron (EN GJS 700-2) castings has been investigated. Axial fatigue tests under nominal load ratio R=0 have been performed on specimens taken from the core of large casting components. Metallographic analyses have been carried out by means of optical microscopy and important microstructural parameters that affect the mechanical properties of the alloy, such as nodule count, nodularity and graphite shape, were measured. Furthermore, Scanning Electron Microscopy was used to investigate the fracture surfaces of the samples in order to identify crack initiation and propagation zones. Cracks initiation sites have been found to be microshrinkages close to specimens\u2019 surface in most cases. It was found that in-mould inoculant composition strongly influences the alloy microstructure, such as nodule count and shrinkage porosities size, as well as the fatigue resistance of heavy section ductile iron castings

Review of recent advances in local approaches applied to pre-stressed components under fatigue loading

Fatigue strength of mechanical components in the high cycle regime depends on both the applied loading and the intensity of any residual stress field induced by either non-homogeneous plastic deformation or the solidification of a local portion of material due to welding operations. In presence of geometric variations that are amenable to being modelled as a sharp V-notch, the residual stress distribution near the notch tip is singular and follows the same form as the solution obtained by Williams in 1952 where the intensity of the asymptotic stress field is quantified by the notch stress intensity factor (NSIF). However, the residual stress varies during fatigue loading and a stable value may be reached. Numerical models have been developed for the calculation of the residual NSIFs and their variation under fatigue loading. Taking advantage of these models, new local approaches have also been recently developed which are able to predict the fatigue strength of pre-stressed notched components. The present paper provides a brief review of such recent advances

Design for recycling in a critical raw materials perspective

The European Union (EU) identified a number of raw materials that are strategic for its economy but suffer at the same time from a high supply risk. Such critical raw materials (CRMs) are used in a wide range of commercial and governmental applications: green technology, telecommunications, space exploration, aerial imaging, aviation, medical devices, micro-electronics, transportation, defense, and other high-technology products and services. As a result, the industry, the environment, and our quality and modern way of life are reliant on the access and use of them. In this scenario, recycling may be a strategic mitigating action aimed at reducing the critical raw materials supply risks. In this work, a design strategy is proposed for alloys selection that minimizes the number of CRMs with the lowest end-of-life recycling input rate. The method is illustrated with an example

Materials selection in a critical raw materials perspective

Critical Raw Materials (CRMs) are those raw materials that are economically and strategically important for the European economy but have a high-risk associated with their supply. Used in environmental technologies, consumer electronics, health, steel-making, defence, space exploration, and aviation, these materials are not only 'critical' for key industry sectors and future applications, but also for the sustainable functioning of the European economy. In this scenario, 'mitigating actions' need to be developed to reduce criticalities linked to the use of those raw materials. Recycling and substitution, when possible, are strategic solutions but a more efficient use of such CRMs in design, obtained by a correct alloy selection, is become nowadays mandatory.A method for metallic alloys selection in a CRMs perspective, based on the definition of the alloy critical index, is described. The proposed method allows selecting the alloy for the current application that minimizes its criticality associated to CRMs. The method is illustrated with examples. Keywords: Mechanical design, Materials selection, Critical raw material, Metallic materia

On the use of the Peak Stress Method for the calculation of Residual Notch Stress Intensity Factors: a preliminary investigation

Residual stresses induced by welding processes significantly affect the engineering properties of structural components. If the toe region of a butt-welded joint is modeled as a sharp V-notch, the distribution of the residual stresses in that zone is asymptotic with a singularity degree which follows either the linear-elastic or the elastic-plastic solution, depending on aspects such as clamping conditions, welding parameters, material and dimension of plates. The intensity of the local residual stress fields is quantified by the Residual Notch Stress Intensity Factors (R-NSIFs), which can be used in principle to include the residual stress effect in the fatigue assessment of welded joints. Due to the need of extremely refined meshes and to the high computational resources required by non-linear transient analyses, the R-NSIFs have been calculated in literature only by means of 2D models. It is of interest to propose new coarse-mesh-based approaches which allow residual stresses to be calculated with less computational effort. This work is aimed to investigate the level of accuracy of the Peak Stress Method in the R-NSIFs evaluation

Alloy Substitution in a Critical Raw Materials Perspective: A systematic approach

Since many years, the European Community has been monitoring some raw materials because of their high importance to the European Union economy and their high supply risk. Such raw materials, classified as critical, form a strong industrial base, producing a lot of goods and applications used in everyday life and modern technologies. Many critical raw materials are used to produce alloys and their high supply risk may constitute a serious problem for the future world economy and technological progress. Mitigating actions are therefore needed such as recycling, material efficiency improvements and, when possible, material substitution. In the present work, a systematic approach for alloy substitution in a critical raw materials perspective is developed. The method is illustrated with an example

Understanding powder bed fusion additive manufacturing phenomena via numerical simulation

The increasing interest in additively manufactured metallic parts from industry has issued a formidable challenge to the academic and scientific world that is asked to design new alloys, optimize process parameters and geometry as well as guarantee the reliability of a new generation of load-bearing components. Unfortunately, understanding the interaction between different phenomena associated to metal-additive manufacturing processes is a very difficult task. In this scenario, numerical modelling emerges as a valid technique to face problems related to the influence of process parameters on metallurgical and mechanical properties of additively manufactured components. This contribution is aimed at summarizing the most important outcomes about metal-additive manufacturing process obtained via numerical simulation with particular reference to powder bed fusion techniques. The fundamentals of additive manufacturing numerical simulation will be also explained in detail. Thermal, metallurgical as well as mechanical aspects are covered

Thermal load-induced notch stress intensity factors derived from averaged strain energy density

Under the hypothesis of steady-state heat transfer and plane-strain conditions, the intensity of the stress distributions ahead of sharp V-notch tips can be expressed in terms of thermal notch stress intensity factors (thermal NSIFs) which can be used for fatigue strength assessments of notched components. The calculation of thermal NSIFs requires both an uncoupled thermal-mechanical numerical analysis and a very refined mesh. For these reasons, the numerical simulation becomes considerably expensive and time-consuming above all if large 2D or 3D models have to be solved. Refined meshes are not necessary when the aim of the finite element analysis is to determine the mean value of the local strain energy density on a control volume surrounding the points of stress singularity. On the other hand, the NSIFs value can be directly determined by the strain energy density. In this work, the method for rapid calculations of NSIFs based on averaged strain energy density, recently published in literature, is extended to thermal problem