1,721,119 research outputs found
Evaluating the Effect of Deposition Strategy on Mechanical Characteristics of 316L Parts Produced by Laser Powder Directed Energy Deposition Process
Full text linkThe production of large components, the possibility to repair damaged parts and the ability to produce components of multi-graded or functional-graded materials are the main drivers of the research and the application of the Laser Powder Directed Energy Deposition (LP-DED) process. However, the knowledge of the process and of the relationships among the process parameters and the characteristics of the produced part is currently not completely understood. The aim of this paper is to fill the current gap in the scientific literature related to the effect of the deposition strategy on the part quality. Therefore, the influence of two of the most important parameters, namely the deposition path and the idle time, on the residual stresses and porosity is evaluated on 316L samples produced by the LP-DED process. The obtained results show that both parameters have a high influence on the porosity level and the residual stresses. In particular, it can be seen that a high value of idle time worsens both porosity and residual stresses. Then, it is also observed that the raster deposition path leads to a lower value of stresses
Intensive Computational Forecasting Approach to the Functional Demographic Lee Carter Model
No full textMutual peer-to-peer insurance: The allocation of risk
No full textThis work focuses on a modern typology through which mutual solidarity in the insurance sector finds application: peer-to-peer insurance. This cooperative insurance model arises from the translation of the sharing economy concept into insurance risk management, and it is realized thanks to the use of digital technology connecting policyholders and sharing risks. The participants to a peer-to-peer insurance scheme share the first layer of their cumulative losses, while it is possible to transfer to a third part the higher layer. To enter the mutual group, each participant has to pay an initial contribution based on a risk-sharing rule that has to be intuitive and transparent. According to the most considered conditional mean risk-sharing rule, the participant has to contribute with an amount equal to the expected value of the risk he brings to the pool given the total loss distribution. We propose to modify the conditional mean risk-sharing rule with an ex-ante contribution that takes into account a safety loading to hedge the possible fluctuations of total losses
Current research and industrial application of laser powder directed energy deposition
Full text linkAdditive Manufacturing (AM) technologies are recognized as the future of the manufacturing industry thanks to their possibilities in terms of shape design, part functionality, and material efficiency. The use of AM technologies in many industrial sectors is growing, also due to the increasing knowledge regarding the AM processes and the characteristics of the final part. One of the most promising AM techniques is the Directed Energy Deposition (DED) that uses a thermal source to generate a melt pool on a substrate into which metal powder is injected. The potentialities of DED technology are the ability to process large build volumes (> 1000 mm in size), the ability to deliver the material directly into the melt pool, the possibility to repair existing parts, and the opportunity to change the material during the building process, thus creating functionally graded material. In this paper, a review of the industrial applications of Laser Powder Directed Energy Deposition (LP-DED) is presented. Three main applications are identified in repairing, designed material, and production. Despite the enormous advantages of LP-DED, from the literature, it emerges that the most relevant application refers to the repairing process of high-value components
Dimensional and geometrical tolerance synthesis based on constrained optimisation: An industrial case
No full textThis paper develops a method for optimum tolerancing of components in assemblies. This approach, based on the solution of a constrained optimisation problem, has been applied to an industrial case of an opening door system. The equation to minimise is a manufacturing cost-tolerance function that describes the relationship between tolerance values and manufacturing cost. A set of equations, representing the constraints used in the optimisation problem, is formulated based on the design constraints and assembly requirements. The equations obtained for the optimisation problem are solved to determine the optimum tolerances satisfying all the assembly requirements and all tolerance constraints. Copyright © 2008 Inderscience Enterprises Ltd
A hybrid modeling of the physics-driven evolution of material addition and track generation in laser powder directed energy deposition
Full text linkMitigation of Residual Stress and Distortion of AlSi10Mg Parts Produced by Laser Powder Bed Fusion through a Proper Selection of Support Geometry
Full text linkLaser beam powder bed fusion (LB-PBF) is an edge additive manufacturing technology that allows complex near-net shape components to be produced. The freedom of design of the LB-PBF process makes it possible to produce optimized geometries, driving the application of this process in sectors in which high performance is fundamental such as aerospace and automotive. However, the building process inherently generates residual stresses in the part and the use of support structures become essential to anchor the part to the building platform and avoid problems in the downfacing surfaces that may warp or collapse during the production process. In this paper, different support densities obtained using different geometries of support structures are investigated to evaluate how they affect the residual stress distribution in the supported part. Two families of support structures were considered, linear-type and volumetric-type, including also a hybrid support structure that combined a massive volume topped by a linear support structure. Results highlighted that the combined choice of support density and geometry influences the magnitude and the distribution of sub-superficial residual stresses near the support-part interface and that appropriate design is essential to prevent excessive distortion or failure
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