1,721,916 research outputs found
Sensitivity analysis of model parameters on finite element simulation of orthogonal cutting
No full textResidual stress analysis of thin AlSi10Mg parts produced by Laser Powder Bed Fusion
Get PDFAmong the various Additive Manufacturing (AM) technologies available for metal part production, powder bed processes are the most promising for industrial mass production. However, one obstacle to the widespread adoption of AM technologies is the effect of the residual stress state on the integrity and lifetime of parts. The residual stress state is influenced to a great extent by the geometry and orientation of the part, and such conditions as the distance of the part regions from the building platform or geometrical constraints may change the stress values and distribution. This work describes an experimental activity that has made it possible to draw the trend of the residual stress beneath the surfaces of thin samples produced in AISi10Mg alloy through a Laser Powder Bed Fusion (L-PBF) process, in order to evaluate how stresses are altered by different geometrical constraints
History of residual stresses during the production phases of AlSi10Mg parts processed by powder bed additive manufacturing technology
No full textResidual stresses can be detrimental to the proper functioning and the structural integrity of built parts. During the selective laser melting (SLM) process, the scanned layers are subjected to rapid thermal cycles. Steep temperature gradients generate residual stresses. In this paper, the semi-destructive hole-drilling method has been used to measure the residual stresses on AISi10Mg parts fabricated by means of an SLM process. The evolution of the profile of the residual stresses of the samples is illustrated in function of the process phase (as-built, after the thermal treatment, after shot-peening) for samples with and without supports. The outcomes have shown the presence, on the as-built components, of high tensile stresses that the usual post-processing operations are not able to minimise. This paper provides a new knowledge on the history of residual stresses during the production phases of metal parts through powder-bed additive manufacturing technology
Modellazione e simulazione agli elementi finiti dei processi per asportazione di truciolo - Parte 2
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Investigation of dimensional and geometrical tolerances of laser powder directed energy deposition process
Get PDFLaser Powder Directed Energy Deposition (LP-DED) is a promising Additive Manufacturing (AM) technology that offers the opportunity of repairing and revamping damaged or outdated parts and molds. Notwithstanding, it should be considered that the low surface quality of the produced parts makes post-processing operations necessary in order to meet the industrial requirements, and these operations strongly depend on the accuracy of the produced parts. In this paper, firstly an artifact for the LP-DED process, including classical features with and without curvatures, is proposed. Then, the dimensional accuracy and geometrical tolerances of the features are evaluated, limited to AISI 316L stainless steel. The findings of this work showed that the dimensional and geometrical tolerances of the LP-DED process are comparable with those of sand casting. On the other hand, tolerances are lower compared to Laser Beam Powder Bed Fusion (LB-PBF) technologies but are similar to those observed in Electron Beam Powder Bed Fusion (EB-PBF)
An adult case of eosinophilic pyloric stenosis maintained on remission with oral budesonide.
No full textOn the quality of unsupported overhangs produced by laser powder bed fusion
Get PDFOne of the main design constraints for additive manufacturing is the definition of downward-facing surfaces, which can lead to problems, like part failing or warping, during construction and poor surface quality. In this paper, a specific index has been defined to represent the surface quality of the downward-facing surfaces induced by the laser powder bed fusion (L-PBF) process. In order to validate the quality index, a design of experiment (DoE) that considers geometric parameters of the overhangs has been defined and carried out, and the quality of resulting surfaces has been evaluated using an optical scanning system. The statistical analysis (ANOVA) has allowed identifying the relationships between significant geometrical parameters and the quality index here proposed
A hybrid modeling of the physics-driven evolution of material addition and track generation in laser powder directed energy deposition
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