1,720,998 research outputs found
The design process of additively manufactured mesoscale lattice structures: A review
Full text linkThis review focuses on the design process of additively manufactured mesoscale lattice structures (MSLSs). They are arrays of three-dimensional (3D) printed trussed unit cells, whose dimensions span from 0.1 to 10.0 mm. This study intends to detail the phases of the MSLSs design process (with a particular focus on MSLSs whose unit cells are made up of a network of struts and nodes), proposing an integrated and holistic view of it, which is currently lacking in the literature. It aims at guiding designers' decisions with respect to the settled functional requirements and the manufacturing constraints. It also aims to provide an overview for software developers and researchers concerning the design approaches and strategies currently available. A further objective of this review is to stimulate researchers in exploring new MSLSs functionalities, consciously considering the impact of each design phase on the whole process, and on the manufactured product
The influence of slicing parameters on the multi-material adhesion mechanisms of FDM printed parts: an exploratory study
Full text linkThe potentiality of the Fused Deposition Modeling (FDM) process for multi-material printing has not yet been thoroughly explored in the literature. That is a limitation considering the wide diffusion of dual extruders printers and the possibility of increasing the number of these extruders. An exploratory study, based on tensile tests and performed on double-material butt-joined bars, was thus conceived; the aim was to explore how the adhesion strength between 3 pairs of filaments (TPU-PLA, PLA-CPE, CPE-TPU) is influenced by the material printing order, the type of slicing pattern used for the layers at the interface, and the infill density of the layers below the interface. Results confirm the effectiveness of mechanical interlocking strategies in increasing the adhesion strength even when thermodynamic and diffusion mechanisms of adhesion are not robust enough. Besides, thermal aspects also demonstrated to play a relevant role in influencing the performance of the interface
Correct use of materials and technologies for a sustainable design: the study of "Acrilica" lamp by Joe and Gianni Colombo
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Cold crystallization behaviour of a commercial Zr44-Ti11-Cu10-Ni10-Be25 metal glassy Alloy
No full textCold crystallization behaviour of a commercial Zr44-Ti11-Cu10-Ni10-Be25 metal glassy Allo
Post-processing treatments to enhance additively manufactured polymeric parts: a review
Full text linkThe potential of additive manufacturing to produce optimised and customized polymeric parts is often impaired by poor surface finish, low mechanical properties, and insufficient dimensional accuracy. Post-processing treatments are usually adopted to address these issues. Scientific community and industrial actors are engaged in the development and use of post-processing to enhance the performance and widen the range of application of polymeric components manufactured by additive technologies. The present work aims to provide an exhaustive classification and discussion of the post-processing treatments, as well as an extensive literature review of the approaches proposed within the scientific community. A holistic view of post-processing is provided, including a discussion of the benefits associated with each technique as well as its side effects. This work is intended to support the selection of the most appropriate post-processing by considering multiple aspects such as the material, part geometry, processing time, costs, and treatment specificity
Tintoretto Unveiled: Interactive Virtual Experience for Artworks
No full textConventionally, visitors of exhibitions cannot directly interact with artworks but remain mainly passive. This work presents a new way to discover paintings through an extended reality application with the aim of enhancing visitors’ engagement. The workflow consists of digitally recreating a painting. All its constitutive elements are contoured and then removed by the artwork. These elements will be unveiled by the visitors with gesture interaction. The discovery of each element is followed by additional information on the subject. The application also proposes an alternative experience where the user paints the components of the artwork with gestures. The hands’ position was tracked by the Leap Motion Controller, an optical sensor by Ultraleap. The process has been applied to one of the Tintoretto’s pieces of art: “L’Annunciazione del Doge Grimani”. The extended reality application has been experienced by over twenty thousand visitors at the dedicated exhibition. Numerous positive comments received from both visitors and guides are encouraging
Additive manufacturing of heterogeneous lattice structures: An experimental exploration
No full text3D printed heterogeneous lattice structures are beam-and-node based structures characterised by a variable geometry. This variability is obtained starting from a periodic structure and modifying the relative density of the unit cells or by combining unit cells having different shapes. While several consolidated design approaches are described to implement the first approach, there are still computational issues to be addressed to combine different cells properly. In this paper, we describe a preliminary experimental study focused on exploring the design issues to be addressed as well as the advantages that this second type of heterogeneous structures could provide. The Three-Point-Bending test was used to compare the behaviour of different types of heterogeneous structures printed using the Fused Deposition Modeling (FDM) technology. Results demonstrated that the possibility of combining multiple unit cells represents a valid strategy for performing a more effective tuning of the material distribution within the design space. However, further studies are necessary to explore the behaviour of these structures and develop guidelines for helping designers in exploiting their potential
The effect of longitudinal rails on an air cavity stepped planing hull
Full text linkThe use of ventilated hulls is rapidly expanding. However, experimental and numerical analyses are still very limited, particularly for high-speed vessels and for stepped planing hulls. In this work, the authors present a comparison between towing tank tests and CFD analyses carried out on a single-stepped planing hull provided with forced ventilation on the bottom. The boat has identical geometries to those presented by the authors in other works, but with the addition of longitudinal rails. In particular, the study addresses the effect of the rails on the bottom of the hull, in terms of drag, and the wetted surface assessment. The computational methodology is based on URANS equation with multiphase models for high-resolution interface capture between air and water. The tests have been performed varying seven velocities and six airflow rates and the no-air injection condition. Compared to flat-bottomed hulls, a higher incidence of numerical ventilation and air–water mixing effects was observed. At the same time, no major differences were noted in terms of the ability to drag the flow aft at low speeds. Results in terms of drag reduction, wetted surface, and its shape are discussed
A Wearable Device to Detect in Real-Time Bimanual Gestures of Basketball Players during Training Sessions
No full textThe paper describes the design of a wearable and wireless system that allows the real-time identification of some gestures performed by basketball players. This system is specifically designed as a support for coaches to track the activity of two or more players simultaneously. Each wearable device is composed of two separate units, positioned on the wrists of the user, connected to a personal computer (PC) via Bluetooth. Each unit comprises a triaxial accelerometer and gyroscope, a microcontroller, installed on a TinyDuino platform, and a battery. The concept of activity recognition chain is investigated and used as a reference for the gesture recognition process. A sliding window allows the system to extract relevant features from the incoming data streams: mean values, standard deviations, maximum values, minimum values, energy, and correlations between homologous axes are calculated to identify and differentiate the performed actions. Machine learning algorithms are implemented to handle the recognition phase
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